The BSA A7-A10 Forum

Technical (topic titles must be descriptive) => Lucas, Ignition, Charging, Electrical => Topic started by: MG on 22.02. 2011 19:18

Title: mag points timing made dead easy - DIY magneto buzzer
Post by: MG on 22.02. 2011 19:18
Hi chaps!

When trawling the web recently I stumbled upon this: (

A dual magneto timer/buzzer (designed for aircraft engines with twin mags), for only 23 US$!
So I ordered two in kit form which were shipped express and arrived within 10 days here in Austria.

Everything that is required to build the tester is included in the kit, only the battery (9V block) is not supplied.
I built both today, and to get straight to the point, they work a treat! As soon as the points open the according LED will go on (red wire - red LED, green wire - green LED) and it makes an unmistakable buzzing sound.

Assembly was straight forward, the instructions are very good. If you don't have any experience in soldering PCB boards or don't know where the hot end of the soldering iron is, it is probably better to get the assembled and tested version for 37 US$ though.
The tester itself is built around a programmable microprocessor, with some nice features, like auto power off, low batt warning, etc.

When using on our single mags, you will only need to connect one input wire (red or green) to the points plate bolt, the other has to be connected to ground (i.e. the black lead/mag body). Otherwise the non-connected input LED will blink and the device will beep to indicate an unknown mag status/bad connection. Connecting it to ground will disable the channel.
OTOH the two channels will be very handy for V-twin bikes with twin mags (should you ever come to work in a Brough Superior or something  ;) ).

Anyway, the guy's name is Paul Brewington, I asked him for permission to write a few lines here on the forum, I'm not affiliated with him in any way, just a happy customer. Really excellent value for the money, highly recommended, no more need to deal with tiny bits of fag paper!  *yeah*

Cheers, Markus
Title: Re: mag points timing made dead easy - DIY magneto buzzer
Post by: iansoady on 23.02. 2011 10:52
That does look good. I'd thought of making something to detect the difference between points open & closed with a Wheatstone bridge but I never really got my head around it.
Title: Re: mag points timing made dead easy - DIY magneto buzzer
Post by: MG on 23.02. 2011 11:05
yep, I also thought about building something, but then I found Paul's kits. There's no way you can do this for 23$ for a single tester, with cases, a professional PCB (incl. solder resist and overprint), components, etc.
Title: Re: mag points timing made dead easy - DIY magneto buzzer
Post by: groily on 23.02. 2011 11:14
Nice one Markus, thanks a lot. Just ordered one, but I cheated and will let him screw it together as he'll be better at it than me. Still a good deal even with the postage and possibly EU customs depending on vigilance level, and a lot better than taking the centre screw out (my usual) and praying or using rizlas. Really good it's for synchronising twin mags - I know a couple of places hereabouts where that would be very handy.