The BSA A7-A10 Forum

Technical => Lucas, Electrical, Ignition => Topic started by: groily on 16.09. 2009 13:48

Title: Thorspark Electronic Ignition
Post by: groily on 16.09. 2009 13:48

Quote
Original post from mike667:

Hey Gang
 anybody have any experience on the thorspark electronic thingy's , always see them advertised on ebay-  they have them in 6V and use the lucas mag housing - seems like a good way to have benefit of  electronic ignition and retain looks of original -  thx! mike


Haven't got one of my own but have seen them on 2 twins (not BSAs) I know well and they have done fine for several years.
 
Yup, electronic should be better - the downside in my opinion is that a 6v dynamo with 60W to play with is a bit marginal. I have one classic 'electronic' (Boyer Bransden) twin in the shed - and the ignition is certainly impressive. But that has a 180W alternator and electronic regulator/rectifier, so there's power to spare. I only feel confident without a mag with 12v and an alternator with modern regulation. And the biggest battery that'll fit in the space.
For 290 bucks you could pretty much get a mag restored. You could certainly get all the bits for that money for home-assembly.
Really depends what you're going to do with the machine in terms of daylight/night riding, on your own or in a group, etc - and how far from home if the dynamo or regulator goes awol and leaves you with that flattening battery syndrome. If I really wanted electronic sparks and had to stay with a dynamo, I'd convert to 12v, get a 12v version of the kit or a similar one, a DVR2 regulator . . .  and the biggest battery, etc.
Title: Re: Re: Thorspark Electronic Ignition
Post by: beezalex on 16.09. 2009 15:03
I think using any battery-powered ignition with an E3L generator is asking to be stranded.  Get your mag properly rebuilt and it will outlive your charging system by a factor of at least four.  You can ride home with your lights dim, but you can't ride home without your ignition working.

Just my 2cents worth.
Title: Re: Re: Thorspark Electronic Ignition
Post by: mike667 on 16.09. 2009 17:16
I think using any battery-powered ignition with an E3L generator is asking to be stranded.  Get your mag properly rebuilt and it will outlive your charging system by a factor of at least four.  You can ride home with your lights dim, but you can't ride home without your ignition working.

Just my 2cents worth.

thanks guys - good info - just got an extra mag, guess i'll just get it rebuilt rather than mess around

 Alex - my lights have been dim for years - why else would i have a shed full of 60-70 euro bikes in various states of decay....
Title: Re: Re: Thorspark Electronic Ignition
Post by: groily on 16.09. 2009 18:02
Reckon that's the best plan.
No idea obviously what your options are over there for getting the job done, but SRM sell most of the required bits, including armatures on an exchange basis (which not everyone will do), and I currently have another K2F with Dave Lindsley in the UK on behalf of a local friend for a full rebuild. There be others, as discussed in threads here from time to time (Sean Hawker springs to mind), but I hope there's the same expertise on hand a bit nearer home, where the dollar goes a lot further. Turn-round times for rebuilds run from about 4 to about 10 weeks this side of the water, with a stock 2-yr warranty. Exchange parts come by return post. Independent Ignition Supplies have all the small bits as well, but as someone else pointed out, the postal charge can be pricier than the bits.
Title: Re: Re: Thorspark Electronic Ignition
Post by: spyke on 16.09. 2009 18:43
Hi,
Although I havn't had experience myself with one of these what about one of those french 12 volt alternators (as advertised in Old Bike Mart) in the E3L shape.You could then have the best of three worlds ie. original look,12v elec ,electronic ignition,

Spyke
Title: Re: Re: Thorspark Electronic Ignition
Post by: beezalex on 16.09. 2009 18:52
The Alton alternator is nice and certainly will give you better lights and allow you to run electronic, but for the cost of an Alton and electronic ignition, you can get about three K2F's professionally rebuilt.
Title: Re: Re: Thorspark Electronic Ignition
Post by: Thorspark on 17.07. 2010 20:42
A discussion of Thorspark power draw.

I have read various comments on forums saying that the fitting of an electronic ignition to a 6 volt bike will leave you stranded.  We make the Thorspark electronic ignition, and beg (obviously) to differ.  The comments normally go on to recommend various 12 volt conversions and magneto re-conditioners.

The 12 volt Thorspark kit draws a maximum of 1/4amp, the 6 volt version a bit less.   This equates to a power draw of less than 3 watts for the 12 volt version, and just over 1 watt for the 6 volt.  This is not a large extra heavy load on the bike's electrics.

I have seen advise on various forums that if you do not upgrade your bike's charging to 12 volts, it will not be up to providing 1 watt of power for the electronic ignition.  This is self evidently rubbish.  It doesn't matter whether you have 6 or 12 volts, as long as you have a battery that isn't shagged out, and that actually charges as you drive along, then you will be fine.

If you use the Thorspark, and you develop a charging fault, with either 6 or 12 volt, you will still have several hours of running with your lights off, but yes, you will eventually get stranded when the battery goes flat, whichever voltage you have.  Obviously a working magneto has the advantage of being self powering, and also if you are running a bike like many of us used to, basically with no electrics, then that is the only way to do it.  These days, however, many of us have bikes that are more or less up to scratch, and lights that actually work. 

I run a 1956 Matchless G11 on 6 volts.  This is unrestored, still has the original six volt dynamo, which as far as I am aware hasn't been re-conditioned, and the Thorspark electronic ignition.  When I bought the bike it had a recently reconditioned magneto, which didn't work despite costing several hundred pounds, and the original Lucas voltage regulator, which seemed to work sometimes but not at others.  I fitted a solid state voltage regulator made by AO services and supplied by Draganfly motorcycles, which has transformed the electrics.  The lights, although not as bright as modern bikes, now work similarly, they dim very slightly on tickover, and go to full brightness the moment you rev above a tickover.  With the lights on, the ammeter is charging at 15 miles per hour in 4th gear.

Magnetos are an excellent piece of kit. However we offer a reasonably priced modern alternative, that has some practical advantages.

It doesn't matter if you have 6 or 12 volts, as long as you don't have a charging fault, then you will have not have a problem.
Title: Re: Re: Thorspark Electronic Ignition
Post by: muskrat on 17.07. 2010 21:58
Thanks for clearing that up Thorspark. I have been an advocate of elc ign for 20 years. I have Boyer on both my A's and love'm. When the dynamo spat the dummy on the cafe I could still get over 100 miles on a tiny 4 amp battery. I haven't had to adjust the timing on the '51 in 12 years. Last night with lights on high beam the amp guage was showing + at 40mph in top gear.
Cheers
Title: Re: Re: Thorspark Electronic Ignition
Post by: bsa-bill on 17.07. 2010 22:38
A welcome mail as far s I'm concerned, my maggie has been reconditioned but left me in some doubt as to it's capabilities recently in regard to providing a good enough spark to ignite 9.5 + 357 cam  compressed mixture.
So much so that I have moderated my projects specs to better reflect my own kicking capabilities as they are now compared to what they were seven years and 2 stone more ago.
I'm keeping Thorspark in mind for possible future mods
Title: Re: Re: Thorspark Electronic Ignition
Post by: Triton Thrasher on 18.07. 2010 22:23

sales talk.

Thanks, obviously.
Title: Re: Re: Thorspark Electronic Ignition
Post by: sparx on 28.07. 2010 22:17
I applaud Thorspark for producing a neat bit of kit, and don't doubt that the switching unit draws a negligible amount of current, but the main current draw is from the ignition coil which has to be fitted in conjunction with the switching unit surely ?
  Or is there something I don't understand here ?   *conf*
Title: Re: Re: Thorspark Electronic Ignition
Post by: MG on 29.07. 2010 11:37
Yep, good point. I guess you won't get any good sparks from 1Watt peak power.
Title: Re: Re: Thorspark Electronic Ignition
Post by: Thorspark on 16.08. 2010 02:25
The power quoted is for the whole kit, including the coil draw. 

If you are using a traditional set of points and a coil for ignition, the points are closed most of the time.  All the time they are closed, there is current running through the coil.  Most is wasted power, as it only takes a very short time for the magnetic fields the coil uses to produce the spark to build up.  After these fields build up, the current continues to run through the coil until the points open to make the spark. This current produces waste heat, so most older coils were full of oil to help cooling.  These points systems consume quite a bit of power, as you mentioned.

The Thorspark is a variable dwell system, ie the coil is only switched on for enough time to make the spark, most of the time it is "off".  Thus the power consumption is much lower.

The spark itself has almost no power, in fact most ignition systems are suppressed, that is they have a large resistor built in to the plug cap or HT lead, in order to limit the current in the spark. 
Title: Re: Re: Thorspark Electronic Ignition
Post by: bsa-bill on 16.08. 2010 12:57
Interesting - I'm coming round to this I think.
As my Rocket Gold Flash is not claiming any originality ( rather the reverse ) and still proving very difficult to start ( in fact at the moment it refuses to ) I'm thinking electronic is maybe the answer, first though I get My Flash MOT'd tomorrow, then I need to swap magneto and maybe even carb from it to the RGF as I know they work.
The Magneto that I had refurbished and on the RGF seems to proved a weak spark and not consistently (although you know my eyes !!) and the carb also might have something to do with it as after lots of kicking the plugs were not wet, so if I can get these two onto my Flash I'll get to see if they work and what's what, ( I know carb's jetted different but should fire up right/wrong)

Sorry went off at a tangent back to Thorspark.

There are as far as I know three or maybe four such systems, Thorspark, Pazon, Wassel and SRM , are any of these the same?
Thorspark as I understand it makes use of the A/R unit and can be fitted into the existing Maggie, can it at a later date be installed in a Billet Maggie replacement body?

Any comments welcome
Title: Re: Re: Thorspark Electronic Ignition
Post by: Alan @Ncl on 09.02. 2011 00:40
Hello Bill, Marcus and all you other Gurus who I note have already discussed Thorspark on this forum. 

I think I have now managed to look at most of the previous posts and it seems to me that this system has considerable attractions, briefly summarised as follows:
1  All of the usual advantages associated with electronic ignition generally: i.e. good starting-spark, reliability, durability, etc.
2  Easily fitted within existing magneto CB housing with minimum changes and authentic appearance.
3  Relatively easy and flexible timing adjustment (although may need a strobe light to set up which sounds potentially messy?).
4  Competitive price.
5  Low power consumption, relative to some competitors (Thorspark claim average 1/4 amp or 3 watts on a 12 volt system).  This is important giving our normal battery charging limitations.

Its this last point that particularly intrigues me as it seems a remarkable achievement.  I know they only turn on the power to the coil the instant before its needed but even if they can charge the coil in say 2 milli seconds (which is very fast) then at 6,000 rpm I estimate the current draw could still, when averaged, get higher than a quarter amp.  Does anyone know what coil resistance is used and what sort of rise time it has? There must also be some power loss in the actual electronics too (albeit small presumably, relative to the coil).

Another point worth a mention is this.  I saw someone selling a used Thorspark on ebay and going back to a mag because he said he had a midrange misfire.  Now I would not read too much into that, one way or another; might have been nothing to do with the Thorspark system.  But it did make me wonder what kind of experiences people were having with them.  Are there any new thoughts on any of this?

Alan

Title: Re: Re: Thorspark Electronic Ignition
Post by: kiwipom on 09.02. 2011 04:12
Hi guys, I also have converted to ?Thorspark ignition? also to 12v dynamo. I haven?t finished the restoration yet so obviously not sure how it will work on the bike but have had it set up on the bench and it sparked well. I couldn?t see the point of having the old armature whizzing around doing nothing so I took some measurements, drew a picture and had a shaft made to take it`s place also did away with those expensive mag bearings and replaced with sealed ones which were much cheaper, still had to use insulators with bearings because of sizes. Have a look at the pics and make comments if you wish, the wiring diagram pic is the one that came with the kit, could have been computer drawn in my view   
Title: Re: Re: Thorspark Electronic Ignition
Post by: Alan @Ncl on 09.02. 2011 11:25
I really liked that Kiwipom.  Very professional and extremely useful to those of us who may be contemplating this route.  Loved Thorspark's technical manual too; clearly they are well into computer aided design.

Looking at this it looks as though there is no intermediate control box between the coil, and the sender unit in the CB housing, on the end of the mag. This would suggest that all the electronics is in there with the pickup. Is that really the case?  I imagined it was only the trigger that was in there (which I was guessing would be a rotating magnet and a static Hall effect transistor pickup). It looks much simpler than I would have expected. If that is the way it is done and if it does what they say, then more credit to them for design simplicity.

Out of interest, are you able to measure the coil resistances of the the primary (red and black) and the secondary (which I am guessing is from one HT lead to the other, if its a dual output coil)?  I could possibly do some sums on this to try and understand how they get such low power consumption. 

Any more close up pic of the magnet, the pickup and the coil could be handy too if not too much trouble. Thanks again for the info.
Title: Re: Re: Thorspark Electronic Ignition
Post by: kiwipom on 10.02. 2011 00:20
hi guys/Alan, Alan you obviously know more about electronics than i and what you say is probably right, everything is in the little red case, and yes the aliminium bit is as you say a rotating head with two magnets, i am incuding some more pics but in two posts as numbers dictate, cheers
Bob
Title: Re: Re: Thorspark Electronic Ignition
Post by: kiwipom on 10.02. 2011 00:55
hi guys/Alan, here is the rest of the instructions,Alan i am not electronics savvy so hope the pics will answer your questions, if anyone wants AutoCad 8 file of shaft i can e-mail it then you can play/adjust at will,the 2D dwg is 239kb, the 3d dwg is 519kb,cheers
Bob
Title: Re: Re: Thorspark Electronic Ignition
Post by: Alan @Ncl on 10.02. 2011 01:24
Thanks Bob
That is great.  Exactly what I wanted and very good of you to do all this.

I am not an electronics engineer but I can now do a bit of crude analysis based on this data and at least come up with some reasonable questions (possibly).  Meanwhile, others on the Forum might feel like doing the same and no doubt some may be better qualified than me to do this.  

To recap, what I think this tells us is that the coil has a 5.5 ohm resistance so will pull about 2 amps when turned on (12 volt system). The HT side is about 17.6 kohms (which roughly suggests about 36,000 volts, I would guess).  

The red box probably contains a Hall effect transistor which is basically a switch which turns on as the magnet approaches, thereby starting the coil charging, and turns off again as it passes.  This in turn triggers the HT spark on both cylinders together, on each engine revolution, using the wasted spark principle. The timing of the spark occurs as the trailing edge of the magnet passes (the equivalent of the contact breaker opening) so it may be possible to set the timing with a 12 volt lamp, just as we can with a mag (although obviously a strobe is probably better).

I will report back if, and as soon as, I have any more but it will be interesting to see if the guys think this makes any sense.

Alan
Title: Re: Re: Thorspark Electronic Ignition
Post by: kiwipom on 10.02. 2011 01:43
hi Alan, as a matter of interest do you Geordy`s not sleep? it must be halfway throuhg the night, it`s 2.45 inthe afternoon here,cheers
Bob
Title: Re: Re: Thorspark Electronic Ignition
Post by: bsa-bill on 10.02. 2011 10:52
Useful post Bob, I think I'll print it off for future reference as I halve shelved the Thorspark idea for the present as both maggies seem to be performing.

btw it's Geordies and it's difficult for us to sleep at night when Sunderland are four places above us in the league *cry*
Title: Re: Re: Thorspark Electronic Ignition
Post by: Alan @Ncl on 10.02. 2011 11:42
You'r quite right Bob.  The Geordie nation never rests.  Thing is, time you get in from the pub and wait for the wetsumping to run its course, its getting on towards one o' clock. And I have a confession for Bill.  Despite living in the great city of Newcastle since 1978, I was born and raised in Sunderland!  How is that for truly cosmopolitan?

Now back to Thorspark.  I did a little check on the data (and can produce the details if anyone is interested) but here is the upshot. Looking at Bob's data I am guessing the diameter of the Thorspark Ally rotor is about 12 mm and the magnet about 3mm across.  Say the engine is running at full chat, 6000 rpm.  On this basis I reckon the coil only gets about 1.6 msec to charge.  This is a very short time as the stuff I have seen on the web seems to suggest that ideally you need about twice this long (the time constant of an R/L circuit is resistance times inductance but we can leave that for now). At 1200 rpm, it gets 8msec which is ample of course so this seems to suggest good fat starting sparks but possibly tailing off a bit at speed.  Remember my initial curiosity was fired by that add for a second hand unit being dumped on ebay because the owner blamed it for mid range misfiring (rightly or wrongly).

However, if my estimates above are correct, this does indeed support Thorspark's claim that the unit will only consume an average of 0.25 amps (my crude estimate is about 0.35 amps but I have made a few speculative assumptions in here). In fact, all my statements should be treated as speculative as anyone who can find good words to say about both Sunderland and Newcastle is obviously a two faced devious scoundrel.

If I can prevail upon Bob's good will with a few more requests:
1  Could you confirm/correct my assumptions about the rotor geometry?
2  I see the instructions lightly refer to the removal of the slipring (camring).  How easy is this in practice? I had a little poke about and it did not seem very anxious to be disturbed.
3  I see the instructions also require the body of the coil to be earthed. I assume this is for the LT circuit as with a twin output coil, I think the HT is a closed loop through both plugs and the cylinder head.  Could you just stick your tester on between each of the four terminals and the coil body to see if any of them are showing any resistance readings?
4  I also notice that to adjust the timing, you have to loosen the centre bolt and move the rotor.  This implies it does not have the little key as in the CB unit and sounds fiddly.  Are these assumptions correct?  Conversely the pic shows a couple of crosshead screws holding the sender unit and I imagined they would be perhaps slotted to permit some adjustment here instead (sound potentially easier).

Thanks again and best wishes to all.

Alan
Title: Re: Re: Thorspark Electronic Ignition
Post by: bsa-bill on 10.02. 2011 14:22
Quote
In fact, all my statements should be treated as speculative as anyone who can find good words to say about both Sunderland and Newcastle is obviously a two faced devious scoundrel.

The fact you own an A10 allows forgiveness

To those of you wondering  Newcastle ( Geordies) and Sunderland ( Makems) share a sporting relationship akin to Australia and England Cricketers, usually friendly banter, match day and Newcastle Brown fetches out the worst in a few hotheads unfortunatley, none the less it good to see both teams doing well so far
Title: Re: Re: Thorspark Electronic Ignition
Post by: kiwipom on 10.02. 2011 21:36
hi guys/Alan Bill, thanks for your humerous note, anyone who comes from the same place as Bobby Charlton can`t be bad, i digress. (1)The rotor is 12.7mm with as you correctly say 3mm magnets, (2)as for the slip ring from memory it was no problem with the end piece removed, a little heat and away it should come, if all else fails brute force and ignorance works every time,lol.(3)there was no resistance between earth and any of the other four terminals,(4)you are correct that there is no key to where the rotor sits on the shaft/no adjustment on the sender holding screws, and yes it would be a good idea to have them slotted for adjustment however moveing the rotor is probably easier. I am thinking of sending these comments to the makers of this unit for their advice,thanks guys,
Bob
Title: Re: Re: Thorspark Electronic Ignition
Post by: Alan @Ncl on 11.02. 2011 01:22
You have delivered the goods yet again.  Thanks Bob (thanks also to Bill for his words of reconciliation).

Just about to turn in so here is tonight's shot.
1  With the exact measurement I now reckon the charging time is about 1.5 msec at 6,000 engine rpm (minor change).
2  In this setup, I don't really see why the coil has to be earthed to work (if it is not completing any circuits which is what I expected) but it can't do any harm and seems intuitively sensible.  Forgot to ask what amperage fuse they give you?  Also how much clearance is there between magnet and trigger unit?
3  Tried warming the camring on my old mag but its very tight. As for the brute force and ignorance, I have an abundant supply of the latter but cant see how to apply the former as I cant get behind it to pull it or whack it?
4  I am guessing you might be able to check the timing as shown in my diagram below but may be wrong as Thorspark do not mension this method. I would expect it to turn on as the magnet approaches then turn off again, very shortly afterwards, as it passes, triggering the spark as it goes.
5  I was also thinking of talking to Thorspark as soon as I feel far enough up the learning curve.  Perhaps we can perform a 'pincer movement'.  So far, I am quite impressed although I still have a couple of niggling doubts.

Over and out

Alan
Title: Re: Re: Thorspark Electronic Ignition
Post by: kiwipom on 11.02. 2011 04:12
hi guys/Alan, very impressive dwg Alan, Thorspark could use it.  Removeing the camring from a spare mag was easyer than i remember with the housing removed of course(pics included)no heat required just a few gentle taps with sharp tool in the two small holes that are in the ring itself. A gap of 15thou between trigger and rotor. Fuse is 15amp, i think that has covered it,cheers,
Bob
Title: Re: Re: Thorspark Electronic Ignition
Post by: groily on 11.02. 2011 07:55
Underneath the little removable bobble on the underside of the cam ring housing (see lower pic), I think you'll find a lock-nutted small screw with an eccentric tip engaging in the cam ring Bob- which is there to give very fine adjustment of the ring-to-mag-body on initial assembly to ensure that points-opening and point of max spark power coincide. Not saying you have to, but I've tended to remove that before pulling the ring!
Title: Re: Re: Thorspark Electronic Ignition
Post by: kiwipom on 11.02. 2011 09:38
hi groily, yes you are right but this one is munted, i was just demonstrating to Alan that it does come out easy and yes Alan will have to note that,cheers
Bob
Title: Re: Re: Thorspark Electronic Ignition
Post by: Alan @Ncl on 11.02. 2011 13:36
Thanks Bob and Groilly.  The Kiwi method worked a treat and it is out.  Noted that screw but thought it was locating rather than holding (I've learned a new word here too, 'munted').  I definitely think the Thorspark instructions could be a bit more explicit about this as there must be others out there like me, with limited imagination or initiative, who would benefit from the advice you lads have given.  In due course, perhaps we may offer them the benefit of our 'collective wisdom' for inclusion in their documentation (I expect they will love that).  I am going to update the diagram by the way so can you check to see I have it right please?

I was thinking about this screw business (noted Bob's lovely gleaming mag seems to have an extra bolt in there too). It seems to me that if you could move the stator a little bit within the casing, possibly even with the engine running under strobe, it would be a good way to fine set the timing then pinch down the screw when finalised. I would have thought it might be quite tricky to get it just right by moving the rotor on its taper and keeping it there while you tighten the centre screw.  This said, it does not seem you (Bob) had any problems with this.

Also wondered what you thought about my suggestion to use a timing light in the switching wire, as in the diagram, to set the timing without a strobe? Perhaps Bob might like to try it and comment if it works? 
Title: Re: Re: Thorspark Electronic Ignition
Post by: groily on 11.02. 2011 15:02
I've seen the screw mod done to give 5+ degrees of movement (10+ on the crank) for this very reason/circumstance. Requires drilling and tapping out the little hole, using a larger screw and machining the offset onto the end bit to get a goodly arc of movement. And probably making up a locknut which will fit snugly without looking like a carbuncle! The one I know of used a 5/16 setscrew, so quite chunky. A good mod, and a lot easier than resetting the whole kit and caboodle for the sake of a couple of crank degrees.
But actually, thinking of fine tuning on the strobe or by ear for that matter, wouldn't lots of adjustment be available on a machine with an ATD if a manual end housing were used, the appropriate Thorspark stator fitted, and the cable attachment modified to operate as a 'vernier' type adjuster a bit like the things on old Lucas car distributors? With an extra locking grub screw somewhere to eliminate the risk of a bit of chatter? Just thinking . . . dangerous pursuit, must desist.

 

Title: Re: Re: Thorspark Electronic Ignition
Post by: Alan @Ncl on 11.02. 2011 15:39
I think yours are great ideas to explore Groily.  

I just hate messing around with the conventional 'timing on the taper' business, primarily because before I got a new autoadvance (many years back) it use to slip all over the place.  Now I loctite it out of paranoia  but then always worry the damned thing might not come off when I want it to. I ended up making slotted bolt holes in the flange of the mag too, which is another approach I know others amongst you have also adopted. Unfortunately the replacement mag I have on now has not been thus treated as I don't have access to machining facilities anymore and found the filing option tedious and messy (at least, the way I did it was).

One of the things I liked about Thorspark is the potential ease of timing adjustment relative to the traditional option. Coupling this with the Groily vernier  suggested approach looks good to me.  I suppose all this depends quite a bit on what sort of fit the Thorspark drum makes in the end housing though as it would have to be able to rotate slightly but not be slack enough to wobble about?

Alan
Title: Re: Re: Thorspark Electronic Ignition
Post by: groily on 11.02. 2011 17:48
The slotted flanges are better Alan if the mag guts are being retained as, er, a magneto, as it's silly to interfere too much with the internal timing of the thing and lose spark intensity.  The mods I have seen and touched were on a V twin, that old old problem, where with a KVF the second cylinder is expected to thrive on a lousy 25 degree late spark and sometimes resents its 2nd class status. The problem is that if you try to get one cylinder to spark ahead of the 'right' moment, it won't as there's nothing there. You can't 'divide and rule' so the trick is to get the first one working strongly as 'soon' as possible, and then get the second one to fire as little late as possible in terms of the armature:magnets, before the spark has dwindled to the level of an old man's passion. Damn fool idea to use a mag designed for a parallel twin in a V, explains twin mags and expensive-to-make bevel gears on some engines, and also explains the early adoption of coil ignition despite inadequate Miller electrics by that much-vaunted purveyor of V twins from Stevenage!
But with an electronic set up, free thinking is the order of the day. And it's fun! (No idea how tight a fit the Thorspark bits are of course, but presumably they won't rattle around in a half-decent housing . . .)
Title: Re: Re: Thorspark Electronic Ignition
Post by: kiwipom on 11.02. 2011 19:55
hi guys, this subject has turned into an interesting exersise pitty more members have not joined in. Alan you will see from previous posts that i have only tested this Thorspark system on the bench to see that it did actually work ok so fine tuning on the bike has not happened as the bike is not finished. that extra bolt is where i have replaced the screw offset adjuster with a locater one, it could have been more discreat but i could always cut the head off, the other chrome domed nut on the opposite end is just filling the hole where the carbon brush was. Alan the idea of setting the timing/test light is good but can`t claim knowledge here or wil be able to try it yet. As a matter of interest with your electrical expertise would it be possible to run a Tachometer from the electronic ignition? Groily your surgestions of an ajusting mechanism would be a good improvement perhaps we should send our thoughts to Thorspark, they may have already thought of it,cheers
Bob     
Title: Re: Re: Thorspark Electronic Ignition
Post by: bsa-bill on 11.02. 2011 20:21
Quote
this subject has turned into an interesting exercise pity more members have not joined in.

Would like to join in Bob, but think I'll learn more reading what you guys are saying, as previously stated I'm interested in the Thorspark ignition (and others that are out there) and if genuine parts keep going for silly prices it could shortly possible to sell a good maggie for more than an electronic kit would cost and make a profit (ha - it'll never happen I know).
Would not consider this option on my Flash but as the RGF project is non stock in so many ways it is worth thinking about should the maggie give trouble , it shouldn't as it has been rebuilt,
And now you mention a Tachometer sensing from the plugs - these I have looked at but they do come at a price, I need to wait until the Chinese are making them.

Well that's my tuppence worth, now back to lurk and learn
Title: Re: Re: Thorspark Electronic Ignition
Post by: kiwipom on 11.02. 2011 20:55
hi guys, good one Bill, yes this is an information highway and like you i have gained a lot from looking and learning, Alan has also joined the club with learning that new word "Munted". It`s a sad day when you don`t learn anything, I await Alan`s opinion on the Tachometer he seams to be the electrical guru, cheers
Bob
Title: Re: Re: Thorspark Electronic Ignition
Post by: Alan @Ncl on 12.02. 2011 10:15
Hello again Bill Bob, Groily and others.  A few points have been raised so here is my latest 'tuppence worth', (to quote Bill).

First, although flattered to be accorded the title of 'electrical guru', I am afraid this is an overstatement of great magnitude. I was a Marine Engineer by background (so am really more comfortable with big diesels and steam plant than electronics).  The little bit I have picked up comes purely from association with others I have worked with (and its over 20 years since I did any real engineering anyway).  

So in my role as student rather than teacher, I like everyone else am learning all the time (and I have learned a lot since coming onto this forum, thanks to all of you out there).

Second point is Bob's Tacho idea.  Bearing in mind reservations about my credentials, as stated above, I think it should be possible to do this quite easily and cheaply working with the low voltage side of the Thorspark.  If it is producing a short 12 volt pulse, once every engine rev, it should be possible to pick this up and compare it against an electronic time base.  Dividing one by the other and outputting as a digital (or maybe even an analogue) signal, suitably scaled, would give speed.  I think there will be chips available at low cost to do this and we have a 12 volt supply readily at hand to drive the thing (power consumption would be negligible).  You could read off with your voltage tester or rig up a permanent display.  Sounds really promising Bob!  There might even be something on the market already made up to do most of this for us.

Related to the above, I had noted from Bob's earlier posts that his bike is still work in progress but the test I was suggesting can be performed on the bench anyway as all you need to do is connect a test lamp (or use the volt tester) and see if it does indeed turn on then off as you slowly turn the magnet past the spot on the red pick up unit.  Its the same idea as testing for a contact breaker opening except there is a much shorter dwell period.

Now to Bill's point.  As you say Bill, you can get devices that pick up speed using an inductive pickup off the HT side but as you also say, these are expensive so if we could do it with what is already available, courtesy of Thorspark, on the LT side, that may be simpler and cheaper.  Come to think of it, its another potential market opportunity for Thorspark to exploit as a 'bolt-on'?

Finally to Groily.  Yes, I miss my slotted mag already as, if I can ever get the bloody thing started (I am going back to my other thread about this soon) I think I may want to retard a bit from the current 3/8.  And it used to be oh so easy before when I had the slotted flange.  

I had not really thought much about the issue of where the optimum magnetic flux comes on a mag and the potential problems with V twins, until you alerted me to this and its a good point that you make. I have very limited practical experience with mags but from a purely theoretical perspective, I would expect the flux to build up following a nominally sinusoidal profile so ideally we try to catch it (i.e. open the points) at exactly 90 degrees and 180 degrees.  However, if we look at a Sine wave, it only drops by about +/-2%  either side of 90 degrees (i.e. Sine 80 and Sine 100 = 0.985).  So it might be more forgiving than may at first be apparent.  Even if out by 25 degrees, Sine 65 = 0.9 so its only lost 10%.  I wonder how these speculations match with reality?

Thanks again to you all

Alan
Title: Re: Re: Thorspark Electronic Ignition
Post by: MG on 12.02. 2011 10:48
Alan,
I talked to an old Bosch service man a few years ago. He said they used to set the mag internal timing 5 degrees late to achieve the best spark. This is to compensate the lag in phase of the current compared to tension caused by the coil inductance. You would want to open the points at the moment of maximum current passing through the primary coil.

You have to keep in mind that the ideal timing is strongly depending on the mag rpm, but 5 deg proved to be a good setting to give a strong spark at low rpm, while the higher voltage at higher rpm will compensate much of the non-ideal timing anyway.
Title: Re: Re: Thorspark Electronic Ignition
Post by: Alan @Ncl on 12.02. 2011 11:16
Ah Yes MG.  As usual, there is obviously more to this than greets the eye, and I know from previous posts that you are a good authority on these things.  I see now that you want to break the LT circuit at the point where current flow (i.e. magnetic flux) is highest, and that this will not coincide uniquely with the point when the winding passes the magnet, taking inductance into consideration.  Presumably as speed increases, the inductive component increases also and therefore pushes the offset even further around (i.e. further away from point of closest geometric proximity)?  Can I ask, do you know which way it goes?  I.e. if the ideal position is 5 degrees after the point of closest geometric proximity (is there a name for this point?) at say 750 rpm, what would it be at 6,000 rpm?

Alan
Title: Re: Re: Thorspark Electronic Ignition
Post by: MG on 12.02. 2011 11:31
sorry Alan, can't help there.
Building a level shifter to measure the spark intensity directly with the oscilloscope is on the to-do list for a loooooong time now.
The plan is to have the mag on the test stand, and check spark intensity at different rpm, to find a good compromise for the internal timing between slow and fast running.

I'm a mechanical engineer myself with in fact some, but still very limited electrical knowledge, so empirical testing it will be (if I ever get 'round to it). *smile*
Only being anal there anyway, in fact a few degrees off aren't really making much difference, like you have stated before. But interesting stuff nevertheless.

Cheers, Markus
Title: Re: Re: Thorspark Electronic Ignition
Post by: lawnmowerman on 12.02. 2011 11:37
I am following this one with interest - not that I am converting to electronic ignition as I am currently getting the mag rebuilt (good enough for aircraft engines then good enough for me) but there are some good learning points regarding mags.
The mag internal flux timing may explain why mine and others' A10s run on one when the manual retard is operated - especially if the mag is on the way out - as the spark will be weaker and due to manufacturing tolerances may only affect one side before ultimately giving up the ghost completely and affecting both sides.

Jim
Title: Re: Re: Thorspark Electronic Ignition
Post by: kiwipom on 13.02. 2011 02:58
hi jim, i get your point but just to add a bit of humour, You don`t have to kick start an aeroplane engine,cheers
Bob
Title: Re: Re: Thorspark Electronic Ignition
Post by: MG on 13.02. 2011 07:55
Quote
You don`t have to kick start an aeroplane engine

http://www.youtube.com/watch?v=hnd05v361qc (http://www.youtube.com/watch?v=hnd05v361qc)

jump to 1:50

 *smile* *lol*
Title: Re: Re: Thorspark Electronic Ignition
Post by: Alan @Ncl on 13.02. 2011 10:01
Greetings again chaps
Loved the video clip and was very relieved to see him get going eventually (better luck than me in this respect).

Noted Jim is in rebuild mode and await with interest the results.  Did his mag tester mate identify any specific problem upon examination?

Also will be interesting to see any results Marcus might come up with in due course with his oscilloscope.  Practice (i.e. empirical testing) is always what matters most in the end but meanwhile, while we await the real world results, here is bit more theoretical musing for our 'delight and delectation'.

If we start with the assumption that the lag is 5 degrees at around starting speed, and then speculate an increase by a factor of about 8 to get from starting to full speed, then the inductive component of the armature impedance (which is the cosine of the lag angle, if I remember correctly) should also rise by about 8 times.  The resistive component stays the same.  On this basis, I reckon the lag will swing to about 35 degrees (tangent comes in here).  So if it had been set up optimally at 5 degrees geometric lag, then at speed it would now be an electrical 30 degrees away from optimal. Since Sin 60 = .87 this would mean you are then potentially down by about 13% from optimal, by this effect alone.  However, as Marcus says, voltage will be much higher anyway at the higher speed so you will have compensated for this many times over.  It would be interesting to see whether any of this speculation bears out in practice?

Meanwhile, it occurs to me that  there is possibly another very practical implication arising from our debate which may appeal to a broader audience.  I read on the forum somewhere that a 1 thou change in contact breaker setting equated to 2 degrees of timing.  If this is correct, we could get quite significant timing adjustment just by fiddling the points gap.  Now I think the argument against this was always that we might spoil the magnetic flux unless we stayed at 12 thou but I think that my point about the relative flatness of the sine function, around the 90 degree position, means that this effect is negligible (I think Marcus agreed this point in his last contribution). In this case we could set up for say 12 thou and 5/16 BTDC (32 degrees) then get all the extra advance we may want up to 3/8 (35 degrees), just by cracking the points open a couple of thou.

Does any of this make sense?

Alan
Title: Re: Re: Thorspark Electronic Ignition
Post by: MG on 13.02. 2011 10:33
Yes, absolutely. I do the final timing by strobe light, and if it is only slightly out, say about 1, maybe 1.5 degrees, I use the points gap tweak to get it just right.

Cheers, Markus
Title: Re: Re: Thorspark Electronic Ignition
Post by: bsa-bill on 13.02. 2011 10:51
Quote
You don`t have to kick start an aeroplane engine,cheers

Excuse me, according to Les Dawson his mother in law kick started Jumbo jets  *smiley4*
Title: Re: Re: Thorspark Electronic Ignition
Post by: Stu55Flash on 13.02. 2011 12:24
The sparke is started by the points just starting to open so how does changing the points gap affect the timing? From the various bike I've had the next development iteration from the 1950's was to keyway the shaft mechanically fixing the magneto to the timing on the crank. The points back plate could then be moved to alter the timing - but again the sparke was initiated by the points just starting to open. The points gap was set independent to this not affecting timing.

Not sure of the logic of using the points gap for timing?

Stu
Title: Re: Re: Thorspark Electronic Ignition
Post by: bsa-bill on 13.02. 2011 13:21
altering the points gap moves the fixed point, the moving point therefore rests at a different place when closed which means the fibre heel is nearer or further from the cam-ring so it contacts the cam ring ramp sooner or later opening the points quicker or later
Title: Re: Re: Thorspark Electronic Ignition
Post by: Alan @Ncl on 13.02. 2011 17:59
I think Bill is quite right and he explains it nicely (but then, we North Easterners always support each other when facing the world beyond).  I did not realise that there was a generation of keyed mag shafts though.  Would the autoadvance pinion on these need to to have a unique matching position relative to its driving pinion with some kind of mark (similar to the camshaft drive)?

And can I just check with Marcus, if you have an auto-advance, how easy it is to actually see where the timing is with the strobe?  With a lightly damped mass spring device like this in the drive train to the mag, I can imagine the timing dances all over the place until the engine revs are high enough to drive it it hard up against the fully advanced stop?  Presumably you have to keep the revs up above some threshold if you want to be able to see what is going on?  This will also apply when setting up a Thorspark system as they recommend using a strobe to set up too.

Also, once you have set it dynamically like this, how well does the timing correspond to what you get using the old static 'fag paper' or the 'timing light across the points' method?
Title: Re: Re: Thorspark Electronic Ignition
Post by: Triton Thrasher on 13.02. 2011 18:18
 I did not realise that there was a generation of keyed mag shafts though.

I don't think any thing like that appeared on old Brit bikes.

Quote
And can I just check with Marcus, if you have an auto-advance, how easy it is to actually see where the timing is with the strobe?  With a lightly damped mass spring device like this in the drive train to the mag, I can imagine the timing dances all over the place until the engine revs are high enough to drive it it hard up against the fully advanced stop?  Presumably you have to keep the revs up above some threshold if you want to be able to see what is going on?  This will also apply when setting up a Thorspark system as they recommend using a strobe to set up too.

Also, once you have set it dynamically like this, how well does the timing correspond to what you get using the old static 'fag paper' or the 'timing light across the points' method?

The strobe image is pretty steady. At idle, you sometimes get an occasional flash out of position. Rev it up and it advances fairly smoothly to the fully advanced position. You have to rev it high enough that it stops advancing.  If the points pivot is worn, you can get strange timing effects at speed, that might make you glad you checked with a strobe.
Title: Re: Re: Thorspark Electronic Ignition
Post by: Alan @Ncl on 13.02. 2011 19:27
Thanks TT on both points.  I note you say its steady at idle as well as at the fully advanced position.  This makes sense as its hard on the two respective stops.  Its particularly interesting though that it also stays steady in the intermediate range which suggests it is very stable and progressive after all (I seem to recall seeing somewhere that it tends to behave more like an on off switch than a proportional device, which is what it is supposed to be).  Good point about showing up things like worn pivots too.  I was wondering though if the timing you arrived at with the strobe came out the same as you thought you had with the old method and if not, which direction, and how far, was it different?

Alan  
Title: Re: Re: Thorspark Electronic Ignition
Post by: Triton Thrasher on 13.02. 2011 20:03
I found, with good points etc., and a new auto-advance I found no difference worth talking about, between strobe and fag paper timing, but if you never do strobe timing, you'll never really know what the timing is doing when running.

With a badly worn points pivot and a solid pinion, so it was fixed at full advance, the timing jumped from about 39 degrees to about 45, at something over 2000rpm.  Quite scary!

At low rpm (and while setting timing with fag paper), I think the slop in the pivot was taken up before the points opened. At higher rpm, the points were getting knocked open instantly, through an inertia effect. That's what I theorised anyway.
Title: Re: Re: Thorspark Electronic Ignition
Post by: Alan @Ncl on 14.02. 2011 00:39
Thanks TT.  Useful info here.
incidentally, walking back from the pub tonight, I realised I had stated in an earlier post on this thread that I had read that 1 thou of points gap equated to 2 degrees of timing difference.  On reflection I think what I read might have been one flat of the CB screw equated to 2 degrees.  Somebody will have the answer to this?  Apologies if I have misled the brotherhood.

Alan
Title: Re: Re: Thorspark Electronic Ignition
Post by: bsa-bill on 14.02. 2011 02:35
You were right first time 1 thou = 2 degrees, this courtesy of Trevor.
This is a powerful bit of info and allows fine setting of timing provided you are deft enough with a feeler gauge, most feeler gauges go down to 1.5 thou, I have discovered a set advertised as going down to 0.0006 ( 6/10ths of a thou ) hopefully this is not a misprint (others sellers stating the same). will report back if they are wrong
Title: Re: Re: Thorspark Electronic Ignition
Post by: Brian on 14.02. 2011 02:42
Jusy for interest here is how BSA recommended to find TDC and set the timing.
Title: Re: Re: Thorspark Electronic Ignition
Post by: groily on 14.02. 2011 11:36
And if anyone wanted a proper drawing of the modified cam ring locator peg I mentioned above, thanks to he who did it I now have same. Slightly at odds with what I remembered, it actually gives 8 degrees variability (crank), uses the same 1/4 bsf thread that is there but with a 5/16ths one-off locknut on a stepped shank - and is a simple turning exercise. It doesn't look like a carbuncle.
I'd be happy to send it to anyone as an e-mail attachment. But can't attach here as despite it's simplicity it's a pdf file and over the 600 wotsit limit and I'm too dumb to know how to shrink it.
Title: Re: Re: Thorspark Electronic Ignition
Post by: Stu55Flash on 14.02. 2011 19:49
I always believed the the auto advance is there to ease starting and reduce kick back fire, therefore when running it should be in the advanced position? Although I don't know where I've had this from.

All this talk of perfect ignition worries me a bit as the best bit about riding my bike is the odd mis-timed spark especially around the country lanes when between close in buildings I can open the throttle and rattle some misfitting window panes. The day it gets that perfect it runs like a japanese sewing machine I will give up!

Having said that I am also having hot starting problems. I dodged a mag rotor rewind on rebuild much to my regret. I am now thinking along the lines of stripping the mag HT wires from the rotor and connecting the low tension to the slip rings and connecting this to an external coils via the pick up leads. This way the ignition works independent of the battery, uses the mag to generate the pulse and time the engine, looks the same and has the advantage of an external ht coil.

Has anyone tried this approach?
Title: Re: Re: Thorspark Electronic Ignition
Post by: lawnmowerman on 14.02. 2011 21:36
Don't see why it would not work Stu with the addition of an ignition switch. It would still be dependant on the battery though to power the coil as you will only be sending an interrupted earth to it and I think you would still need a suitably sized capacitor in circuit. If it could work it will be a fairly cheap fix.
There was an older topic about jury rigging where the HT was fed through a second coil but I think only with limited success.

Jim
Title: Re: Re: Thorspark Electronic Ignition
Post by: Alan @Ncl on 14.02. 2011 23:22
I am falling behind a bit as there have been a few interesting recent posts here. Working back from the most recent, I am really intrigued by Stu's idea and the variation on it (as I understand it) from Jim.  Both certainly worth further exploration.

Next Groily: I would appreciate a copy of your pdf please if you can send to alan.fowler@ncl.ac.uk. Nice sanity check from Brian also noted.

Then to Bill and the issue of how much timing adjustment you can get on the points.  I have been playing around with this wondering where the numbers come from.  Consequently I have come up with the notion that it is approximately 2 thou change in points gap = 1 crank degree, or one flat on the screw = 2 crank degrees.  I attach my calculations for critique by the experts.  This is very provisional as I don't have a good vernier to make accurate measurements or a dial gauge to see what happens in practice.  I hope it is 'right ballparkish' though. If anyone can 'tighten this up' with better input data, then I can modify the calcs accordingly. Better still if those with dial gauges and dexterity with feeler gauges could confirm empirically.
Title: Re: Re: Thorspark Electronic Ignition
Post by: chaterlea25 on 15.02. 2011 21:21
Hi All,
Yes Stu's  method will work, without a battery
BUT!! the connections have to be soldered to the slipring not pushed in
the slipring now has to carry current (not much voltage) also the brushes need to have neglibile resistance
This modified system works on the energy transfer method. You need 2 coils, they have to be AC types
(old honda 50 or italian scooter)
I sucessfully even got a V twin BSA to go on this system,
My brothers early Rudge which ran the mag at engine speed (originally maglita) ran on a conversion like this for years and years
This was back in the days when it was virtually impossible to get a mag rewound at a reasonable cost

HTH
JOhn O R
Title: Re: Re: Thorspark Electronic Ignition
Post by: Alan @Ncl on 15.02. 2011 22:10
I was wondering about a variation on Jim's version as shown in my diagram  below (Battery&DualCoil).  I have an old mag with a knackered slip ring and thought about feeding the CB through the kill circuit as shown.  Could either hide the capacitor in the rotor or mount externally. Note this version does not use the HT pickups at all.  

Another possible further development of this is to add an extra stage using a £10 Maplin electronic conversion so the CB carries only a small current that drives a transistor which then drives the coil. In fact, its almost a Thorspark!  Any thoughts on these ideas?

Alan
Title: Re: Re: Thorspark Electronic Ignition
Post by: trevinoz on 15.02. 2011 22:13
I don't know if any of you have seen a magneto set up on a dedicated tester but it is very interesting to watch.
The spark can be made to jump a set gap or can be set so that the angle of degree of firing can be compared between cylinders.
The primary voltage on our K2Fs is in the order of 200 volts so may be a little high to apply to normal coils but may be OK for AC ignition coils.
  Trev.
Title: Re: Re: Thorspark Electronic Ignition
Post by: Alan @Ncl on 15.02. 2011 22:30
That's interesting Trev.  I was wondering what sort of voltage a mag primary could manage.  It must de able to push a hell of an instantaneous current if only its own internal resistance stands in the way.  I expect the inductance holds it down a bit but wonder if you have any more data around this area.  Presumably the points are having to carry all this current too.  Any idea what it typically manages at kickover?

Alan
Title: Re: Re: Thorspark Electronic Ignition
Post by: chaterlea25 on 16.02. 2011 00:29
Hi All,
The method I used is using separate coils for each cylinder, current is generated by the rotating mag windings
this flows in parallel into the remote coil while the slipring is in contact with the relavent brush
when the points open the collapsing field in the mag  primary causes a pulse into the remote coil giving a spark
The circuit is the same as most flywheel magnetos
The important thing is that the coils Must be from something which had this type of ignition in the first place
6v or 12v coils will not give satisfactory results

The method of using the points only is back to plain battery and coil ign, capacitor can be in the rotor or externally

Regards
John O R
Title: Re: Re: Thorspark Electronic Ignition
Post by: lawnmowerman on 16.02. 2011 08:51
Hi Alan

Your version 2 diagram summarises what I was trying to suggest in my earlier post (but much more clearly - a picture is worth a thousand words) and I would think is the better of the two versions as it does away with the mag completely and just uses it to generate an interrupted earth to the coils using the existing HT leads and pickups so keeping the original look. Perhaps the coils could be tucked under the tank or seat front to hide them away.
We are almost reinventing the wheel here as we are getting close to the modern electronic versions which are currently available (and probably more reliable) and use contacless switching thus doing away with points adjustment and the timing inaccuracies which result if not set exactly right or become evident with wear of the contacts, pivots and heel over time.
I am trying to keep my SR as original as possible so I am sticking with the standard mag solution. I do not use the bike on a daily basis so points wear is not a great concern and once a mag is rebuilt properly and set up right, it should give years of good service.
When I dropped the mag off for rebuild my mate had a quick look and said that the HT slip ring was pretty badly grooved around the circumference with the grooves filled with carbon which is almost impossible to get out without either replacing or re-skimming. He also said that in most cases, if the old type capacitor was still being used it would be breaking down and causing intermittent faults.

Jim
Title: Re: Re: Thorspark Electronic Ignition
Post by: Triton Thrasher on 16.02. 2011 09:29

I am trying to keep my SR as original as possible so I am sticking with the standard mag solution.

Jim
   Even if, or perhaps especially if you want to use the bike on a daily basis, nowadays the route to reliability and riding happiness is a a standard magneto refurbished by Tony Cooper.  I too have jury-rigged a failed mag to work with coil and battery in the distant past and it did work, but with a good magneto, you have less worries and fewer roadside problems and not much maintenance either.                                                                                                                                                                                                                                        I'm delighted to see entusiasts use their ingenuity to fit super ignitions to their bikes, but those who just want to ride an old BSA twin will be better served by the K2F.
Title: Re: Re: Thorspark Electronic Ignition
Post by: lawnmowerman on 16.02. 2011 09:54
Totally agree TT - do it once, do it right and forget about it. When you consider how much we have probably already spent on restoring our bikes then it is false economy trying to save money by not properly refurbing the mags. They are the heart of the bike and can cause so many misleading symptons when they are not working 100%.

Jim
Title: Re: Re: Thorspark Electronic Ignition
Post by: Alan @Ncl on 16.02. 2011 11:31
I have just updated the diagrams in my previous post as having read John's comments, I realised there were omissions in one of them as I had forgotten the HT (now LT) slipring is not continuous but will actually only deliver a pulse over the period that the brass contact lines up with a brush.  I am also including in this post yet another option which I think is the one John is suggesting (and he has actually built one and made it work).  John, is this the way you did yours?  Also what value of capacitors do you recommend and can you fit them near the coils, out of sight, as in the diagram?  Also, do you know what resistance the coils are (or even what inductance if possible?).

Jim, I agree that the battery version diagram in the original post, it is getting close to a conventional electronic ignition but, like a Thorspark, looks original externally.  I reckon this would only consume about 1.1 amp (say 14 watts) on average if used with a Thorspark type coil.  Note it is a wasted spark type as I have drawn it. However, if wired through the HT pickups and made more like John's version, which I think was your original intention, it need not be a wasted spark.

Finally, I agree with all that a properly refurbished authentic mag is probably best especially for some of the original beauties you lads have.  But these options may be useful for skinflints like me with rather un-original looking beasts (though I would still like it to at least look like a mag).
Title: Re: Re: Thorspark Electronic Ignition
Post by: chaterlea25 on 16.02. 2011 20:58
Hi Alan,
Your nearly there  *smile*
The wire from the primary to the remote coil in your drawing is broken by the points
This is incorrect

The wire coming from the primary to the points should be  also connected to the coil via the slipring
As the current flows in the primary when the points are closed it also flows in parallel throuhg the primary of the remote coil (via the slipring)
the current flowing in the magneto rotor basically magnetises the rotor spool (as happens in a normal mag)
when the points open the collapsing magnetic field sends a voltage spike into the remote coils primary
this spike is transformed by the remote coils secondary into the high voltage spark

I dont have an AC coil to measure the resistance here to measure, next time I visit my old homeplace I will have a look for one
The capacitor should be 0.22 micro farad, As used in all old battery and coil or flywheel mag setups
I wonder if a CDI coil would work? maybe not as the charging coils on some CDI units generate around 100volts???


In last months Classic Motorcycle magazine there was an article on energy transfer ignition, the circuit is basically the same, today  I read a letter in reply to the article in whick the writer  rekons the phase waves in the ET system
are too short because of having six magnets on the rotor, reasoning that the waves on a magneto are much longer
as there are only a north and south magnets within the casing
It makes sense in laymans language *conf*

HTH
John O R
Title: Re: Re: Thorspark Electronic Ignition
Post by: Alan @Ncl on 17.02. 2011 00:02
Still not sure I have got this John but have changed my original post and added a new diagram here plus a simplified version to define the basics.  Not sure if I have the condenser right either. Do'nt want to overstretch your patience but if its still not right, and if I had your email, I could send over the powerpoint file.  

Was also wondering if this does not behave more like DC rather than AC in practice as the brass slipring is a bit like one big dynamo commutator segment so the current might always flow into each external primary in one direction only?

Alan
Title: Re: Re: Thorspark Electronic Ignition
Post by: Stu55Flash on 17.02. 2011 18:36
Thats the cct I had in mind. The collapsing field when the points open fires a current through the remote coil.

Stu
Title: Re: Re: Thorspark Electronic Ignition
Post by: chaterlea25 on 17.02. 2011 20:08
Hi Alan,
Yes the circuit is now correct *smile* *smile*
On a twin mag as wew are on about k2f's the current will be going in opposite direction every half revolution
the rotor poles pass the N and S magnets alternatively  ???? making AC

on a single mag one wave will be interupted by the points the next will just flow through the circuit in the opposite direction, so the  spark pulses on a single mag will always be the same polarity

HTH
John O R
Title: Re: Re: Thorspark Electronic Ignition
Post by: Alan @Ncl on 19.02. 2011 13:32
Thanks John and Stu.  Seems I have finally managed to accurately portray what you are saying in my diagrammatic form.  The only other thing about this is the capacitor location.  If we don't want it inside the mag, I think we could get the same effect my mounting it in the kill wire (out of sight) and earthing it (not shown in my diagram yet).  What do you think?

I am also returning to the original Thorspark issue here (have not heard from KiwiPom Bob for a while and wonder how he is getting on with his?).  I attach my speculations about how they actually get such low current but also detailing my provisional concerns about rise time and stability of timing with this device.  I should emphasise this attachment is for critiquing and discussion, not a definitive explanation.  I may put these points to Thorspark in due course, once I have established that I am not talking  crap.

Alan  
Title: Re: Re: Thorspark Electronic Ignition
Post by: lawnmowerman on 19.02. 2011 14:30
Hi Alan

If you put your observations to Thorspark they may well offer you a job as a consultant  *smile*

Jim
Title: Re: Re: Thorspark Electronic Ignition
Post by: Stu55Flash on 19.02. 2011 19:22
Alan

My reading of the Thorspark ignition is that it uses the battery to power the generation of a spark through the HT coil. So all the transistor cct does in the magneto is switch a short burst of current through the HT coil when it senses the magnet or slug on the rotor arm. Hence this current is independent of the magneto. All the magneto is there for is to mount the rotor arm to and time the spark. The magnetic cct in the magneto is not used. I don't see how the rise time of the rotor arm affect current in the cct. The transistor would be calibrated at a trigger level not necessarily at the peak of the rotor signal.

So therefore the current flow is what Thorspark have designed through their device - the little black box that is mounted inside the magneto. I suspect this would on a very short time interval but just enough ampage to provide a good spark from the HT coil. Too much and the life of the coil will be limited and/or battery current wasted. The HT coils are from CDI type ignitions and have very short rise curves [many vK/us] low reluctance coils- not like conventional DC coils or LC circuits.

Sorry but I don't think the calculations are relevant. Anyway for applications such as these the manufacturer would quote RMS values for this kind of application which would be much less (0.707*peak).

Also the capacitor is there to reduce arcing at the points in this respect it provides a short cct to high frequency components of the generated voltage and hence extends the life of the points. The discharge push is a secondary affect. 

All that said I stand to be corrected - Stu
Title: Re: Re: Thorspark Electronic Ignition
Post by: chaterlea25 on 19.02. 2011 22:13
HI Alan, Stu,
Alan,  going back to the ET ignition conversion, the capacitor can be mounted in the rotor or 2 capacitors one on each coil wire (at the coils). theoritically apparently its better to have them near the points (cant remember why *conf*)
wiring off the cutout wire connection is also possible but then you are relying on a good brush connection. I have done this as a get you home bodge *ex* *ex*

Stu, I believe Alan is talking about the magnetic field of the electronic trigger rotor not the mag rotor??

Regards
John O R
Title: Re: Re: Thorspark Electronic Ignition
Post by: Alan @Ncl on 20.02. 2011 09:57
Thanks John and Stu
I think there is no real conflict of opinion beween Stu and Me because as John has said, I have now switched the focus back from magnetos (whence we had drifted, very constructively I hope) to the Thorspark system and my potential reservations, having seen one being 'dumped' on ebay.  In retrospect, I should perhaps have put my earlier schematic of the Thorspark system up there again with my spreadsheet (I am going to do so now).  As Stu says, what is inside the mag has no bearing on this since as far as Thorspark is concerned, the mag is only an autoadvanced drive shaft, and a housing to aesthetically hide the bits (Bob has actually, and rather ingeniously, replaced the mag armature with solid shaft).

Stu adds some useful info here though as I did not realise that Thorspark would use an AC coil designed for CDI systems (Is that Capacitive Discharge Ignition?).  Also, I accept if its AC we would use RMS.  Bob measured the resistance of his Thorspark coil at 5.5 ohms (don't know how we measure inductance though: is there auch a thing as a 'Henry meter'?).  Does that add up with an AC type Stu?  I have a twin output coil on the shelf from a Punto, that shows 0.5 ohms so I would not dare put it on 12 volts and wonder how it was used in situ?  Again, Stu might be able to enlighten me (but I digress a bit).

Thanks for your comments too John about the other half of the thread (magnetos).  I think you are right that feeding the capacitor though the end cap brush might be asking for problems long term.  In an earlier post I had two caps up beside the coils and perhaps that's where they should stay if mounting externally.  I think my concern her though was that although these would deal with surges from the external coil, they might not always accommodate surges from the magneto primary since if the brass segment was not lined up, at the point of breaking the current, there would be no where for the surge to go.  But I suppose it must always be lined up thinking about it as the slip ring is synchronised with the CB opening..

Like John, I seem to remember something about caps needing ideally to be near points, but I can't remember the reason.  I suppose if we think of the hydraulic analogy with a surge tank upstream of a control valve, it makes some intuitive sense.  Its all interesting stuff (well I hope it is!).

Alan
Title: Re: Re: Thorspark Electronic Ignition
Post by: MG on 20.02. 2011 11:48
Quote
I have a twin output coil on the shelf from a Punto, that shows 0.5 ohms so I would not dare put it on 12 volts and wonder how it was used in situ?

They are using something like that, with built-in current limiter:

http://www.alldatasheet.com/datasheet-pdf/pdf/25593/STMICROELECTRONICS/VB921.html (http://www.alldatasheet.com/datasheet-pdf/pdf/25593/STMICROELECTRONICS/VB921.html)


What you are looking for is called LCR meter, used to measure inductance, capacity and resistance.

Interesting thread indeed. Has someone ever actually measured the power consumption of the Thorspark system? Even if it is CDI, you'll need energy to charge the cap(s). The figures they state seem very small.

Cheers, Markus
Title: Re: Re: Thorspark Electronic Ignition
Post by: olev on 21.02. 2011 08:58
The yankee yamaha 650 boys have a neat system.
it could be similar to thorspark.
Check Pamco ignition on the attached link.
http://www.yamahaxs650.com/
I went within a knats whisker of trying to graft one into the A7 before I went my own way.
cheers
Title: Re: Re: Thorspark Electronic Ignition
Post by: Alan @Ncl on 22.02. 2011 15:51
Thanks Olev and Marcus
That picture in the Pamco seems to indicate a fairly simple circuit with a Hall effect transistor driving a power amplifier of the type flagged up by Marcus.  Only two components seem to be presemt; a pull up transistor (I think that's what they call them) and a zener diode.  Looks like anyone with a bit of electronics nounce (probably not me ) could knock up something like this relatively easily? 

I suspect that this is probably what is inside a Thorspark, basically. Makes you wonder why, if it can be done as simply as this, do some of the electronic systems you see look so complicated (even ones that do not have electronic timing advance)?

Marcus, I guess you are saying that if I were to drive the low resistance coil with a current limiting device such as the one you have identified, it would work as designed?

I had another thought about Stu's recent post on this too.  I don't know much about CDI ignition but would like to know more.  Do you think that the 0.5 ohm Punto coil I mentioned is designed for a CDI system and what exactly is 'reluctance'? Is that the same, or similar to, Inductance?  I know they talk about 'reluctors' in the context of car distributors (replacing points) but never understood the term.

Alan
Title: Re: Re: Thorspark Electronic Ignition
Post by: MG on 22.02. 2011 18:41
yes, these devices switch the primary coil and act as current limiter to charge it (with short circuit protection, etc), so actually are doing most of the job. Some external components are required, and you might want some more features and a way of triggering the spark, but it is relatively easy to build a basic electronic ignition module around one of these.

Cheers, Markus
Title: Re: Re: Thorspark Electronic Ignition
Post by: chaterlea25 on 22.02. 2011 19:44
Hi Alan, Markus and All,
For your info, heres a CDI circuit  thats for a Morini 3 1/2
The original morini transducer and coil was a one piece affair quite expensive to replace (2 needed)

I got this circuit on the net somewhere and built 2 of it onto a circuit board, I potted the board into  plastic electrical box 3 x 3in and used some yamaha CDI coils from a breakers, the whole lot cost less than £20 and it would throw a spark over an inch *eek*
The Morini is now long gone *sad2*

Cheers
John O R
Title: Re: Re: Thorspark Electronic Ignition
Post by: Alan @Ncl on 22.02. 2011 23:37
Thanks for the circuit and the info, John and Marcus.  I actually bought a Maplin kit for £10 (which by my reckoning works as in the diagram attached).  I wonder if this does more or less the same thing? It does not seem to have any current limiting capacity though!  I am not completely sure about the implications of positive earth either, if its used with a CB on our bikes (npn vs pnp and all that stuff).

Alan
Title: Re: Re: Thorspark Electronic Ignition
Post by: chaterlea25 on 23.02. 2011 00:44
Hi Alan
the Morini system is self generating, (coil inside the flywheel)
It generates a high voltage to charge the capacitor , I measured it at around  100 volts  *eek*

Cheers
John O R
Title: Re: Re: Thorspark Electronic Ignition
Post by: kiwipom on 25.03. 2011 21:46
hi guys/alan, just keeping in touch between quakes, alan did you ever get that bike going haven`t seen you on the forum for a while,cheers, bob
Title: Re: Re: Thorspark Electronic Ignition
Post by: Alan @Ncl on 25.03. 2011 23:00
Hello Bob
Thanks for asking.  Afraid I gave up a few weeks back and have not been back to it since. Just had a few nice warm days that I should have taken advantage of but have missed the boat now it seems.  Your prompt has awakened me again though so might have another go this weekend.

Out with some friends tomorrow who have just come back from hols in New Zealand.  They loved it.

Alan
Title: Re: Re: Thorspark Electronic Ignition
Post by: kiwipom on 26.03. 2011 02:25
hi alan/guys, thanks for the reply if your friend came down to Christchurch they would have seen the vast amount of damage, it will be years before it is fixed. We are waiting for our insurance payout so we can move on but they like to drag the chain, if i decide to come back to u.k. i will be bringing the A10 with me it was so close to finish but now is back in storage,cheers for now, Bob
Title: Re: Re: Thorspark Electronic Ignition
Post by: Alan @Ncl on 26.03. 2011 10:51
Sorry to hear you were so badly affected Bob. Did not realise you were right in the middle of it all and down in Christchurch. Must have been bloody awful. We sometimes winge a bit about the weather a bit up here at 55 degrees North but at least we don't have issues like that to contend with.  Glad the bike survived in tact, at least, but pity its back on hold.  Best wishes with the recovery strategy.

Alan
Title: Re: Re: Thorspark Electronic Ignition
Post by: lawnmowerman on 26.03. 2011 11:32
Hi Bob

Hope you sort things out soon. If you do decide to come back to the UK then get in touch - if you end up back in Canterbury then you will not be far from me.

Jim