Smiths Chronoelectric tachometer

Shelby-Right said:
Does anyone know what is required for getting a good signal from a magneto HT lead to provide the signal for a new Smiths Chronoelectric tachometer , I know the likes of a timing light type of pickup, sort of products , or those cheap digital gauges just have little clip
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I hope someone comes along with an answer… coz I don’t think it’s possible, I think they use a low tension signal.

Schitsu tachos are cheap, run on an internal battery that lasts a whole season and more, and get their signal from taping a signal wire to the HT lead. Worth considering if you can’t fix the chrono.
 
Fast Eddie said:
I hope someone comes along with an answer… coz I don’t think it’s possible, I think they use a low tension signal.

Schitsu tachos are cheap, run on an internal battery that lasts a whole season and more, and get their signal from taping a signal wire to the HT lead. Worth considering if you can’t fix the chrono.
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I haven't got a chronometric tach , there is one for sale over here for $ 500-600 with a cable and tach gear box but it's off a norton atlas and the seller said it was 1:1 and the tach was slow to return ! . Those 2:1 gear boxes are a ridiculous price, unless its for a tractor , so that's why I thought the new chronoelectric tach , maybe I might email the manufacturer and see if anything is available to get a signal from the HT lead , getting a bit expensive for my old B33 goldstar 🤣🤣 Cheers .
 
I know it's not HT related, but I was getting occasionally erratic behaviour from my Smiths electronic tacho and the Australian agent said that I was likely getting ignition interference (its connected to the dual coil input).
Seem to have fixed it by using shielded speaker wire - just earthed the shield.
 
I use a couple of Daytona revcounters with Lucas mags. Give Digital speedos in the UK a call & get one of the KOSO adapters which work okay. It tie wraps onto one of the plug leads.
 
This is the reply from Caerbont Instruments.

The gauge needs a 12 volt supply and would also need something like a KOSO RPM filter (also 12 volt) to attach to the HT head of the magneto to trigger the tacho.

We do not stock the filter, but they are available on the internet.

You may be better contacting our Australian dealer Howard Instruments for a more local source.

Regards

Peter Wilkinson
Software Engineer
Direct Phone +44 (0)1639 732243
Caerbont Automotive Instruments Ltd
 
My Daytona tach was erratic until I put a resistor inline to the power (?I think? Or was it the pick-up wire?) due to electrical noise.
 
Only Norton Chronometric I have is 2:1.
Scitzu with internal battery may last a season if not too many races. They also have external feed tachos.
As said all electronic tachos may pick up electrical noise.
 
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