Author Topic: test dynamo  (Read 1097 times)

Offline Tumbleweed

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test dynamo
« on: 30.08. 2018 14:48 »
hi everybody  .  I am trying to make a good dynamo out of two old ones .  when I spin it with a drill A/Clockwise I only get2-3 volts set on  20 position on my  meter joining F and D together  to  neg   and pos  to + it wont light a bulb just a faint glimmer, but it motors quite fast.        any ideas TW  how fast does it have to turn befor it works with the dynamo off the bike
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Online bsa-bill

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Re: test dynamo
« Reply #1 on: 30.08. 2018 15:39 »
Quote
oining F and D together  to  neg 


Dynamo body would be neg or pos depending on polarity usually positive earth on these bikes
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline Tumbleweed

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Re: test dynamo
« Reply #2 on: 30.08. 2018 15:53 »
 yes Bill its off my a10 and its +earth  , 
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Online JulianS

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Re: test dynamo
« Reply #3 on: 30.08. 2018 18:14 »
Lots of interesting stuff on electrics on Matchless Clueless site;

https://matchlessclueless.com/

Online bsa-bill

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Re: test dynamo
« Reply #4 on: 30.08. 2018 18:14 »
a week or so ago I got similar results before changing polarity back to positive earth (long story)  , turned out I had painted the dynamo not thinking about it's need to earth, had to rub of the paint (under the strap) and put a piece of copper between the strap and the dynamo, magic upto 20 volts at times
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Online trevinoz

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Re: test dynamo
« Reply #5 on: 30.08. 2018 22:33 »
That is usually indicative of an armature with open circuits.

Offline Tumbleweed

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Re: test dynamo
« Reply #6 on: 31.08. 2018 09:45 »
thanks for your help chaps ,  the matchless site was useful as well     TW
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Offline Tumbleweed

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Re: test dynamo
« Reply #7 on: 03.09. 2018 13:38 »
hi, everybody ,  I have just run a test with a electric drill and at 2000 rpm    I get  14 v charge from it I am hoping this will do for my a10 ?    TW
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Online Rex

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Re: test dynamo
« Reply #8 on: 03.09. 2018 18:54 »
a week or so ago I got similar results before changing polarity back to positive earth (long story)  , turned out I had painted the dynamo not thinking about it's need to earth, had to rub of the paint (under the strap) and put a piece of copper between the strap and the dynamo, magic upto 20 volts at times


It should earth just fine through the ally end plate to the engine.

Online bsa-bill

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Re: test dynamo
« Reply #9 on: 03.09. 2018 19:02 »
Quote
It should earth just fine through the ally end plate to the engine.


Really , I find on mine the cork gasket makes a good insulator  ;)
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Online Rex

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Re: test dynamo
« Reply #10 on: 03.09. 2018 21:16 »
Mine must be a different design then, as the cork gasket only touches in the middle section and the outer portion is well and truly butted up to the crankcase.

Online bsa-bill

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Re: test dynamo
« Reply #11 on: 03.09. 2018 21:20 »
possible the cork has compressed, if the alloy touches first then the cork is doing nothing.
The reason mine did not earth was I had stupidly painted the body ( a bit too well)
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Online trevinoz

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Re: test dynamo
« Reply #12 on: 03.09. 2018 22:42 »
TW, if you are getting 14V the generator is fine.

Offline coater87

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Re: test dynamo
« Reply #13 on: 04.09. 2018 15:29 »
 After some of the hassle I had with mine after rebuild, I would power up a bulb with it before I buckled it up. 14V is nice, but I would make sure it will run a load first.

 Lee
Central Wisconsin in the U.S.

Offline Tumbleweed

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Re: test dynamo
« Reply #14 on: 11.09. 2018 12:16 »
hi folks ,   well I fitted  it to the bike and I don't even get 1 volt direct from dynamo    *sad2*  also I  flashed the F terminal for polarity ,  the D terminal flashes as well  is this normal ?   TW
Semper in excretia sumus solum profundum veriat.