Query on voltage from Coil and protecting Rev counter

bonerp · Post by **bonerp** » Wed Jun 29, 2011 9:01 am

Hi
Had word back from SpeedyCables and my rev counter was reading badly due to a blown protection diode which may be due to high voltage transients in the signal line. They recommended checking the coil.

Should there be a voltage regulator in this line or just ditch the coil and fit a new one?

thanks

Paul

mdmax72 · Post by **mdmax72** » Wed Jun 29, 2011 8:27 pm

Sounds like you may have had a bad coil, maybe??. Was it a cheap one or a bosch blue coil? I read a thread somewhere that someone was selling copies of the bosch blue coil a few years ago, maybe one found its way to you. Not heard of a voltage regulator in between the coil and tacho before...but could be wrong if anyone wants to have a say...

bonerp · Post by **bonerp** » Thu Jun 30, 2011 8:33 am

yeah its a bosch one - I'll get it swapped for another and change all the points and consensor to be on safe side.

impmad2000 · Post by **impmad2000** » Thu Jun 30, 2011 9:40 am

You could try one of these
http://uk.rs-online.com/web/search/sear ... &R=4856992
A trinsient surpressor. It shorts out high voltage spikes.
If the tacho feed is off the points, I recomment a series feed resistor 1W or so, 1K Ohms down to 100 Ohms (As high a value as will still allow the tacho to work) , to the tacho with the ringed end of the transient surpressor connected from the tacho end of the resistor and the other end to ground. If a 20ish Volt device keeps getting spikes it will die and perhaps a higher voltage device will survive lonmger, but protect the tacho less well... some experimentation may be required.
Tim