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warren3200gt wrote:I don't know is the answer Zedhead! just decided to work!

Need to fine tune to sincro revs/leds. Only the ingnition and leds connected hence no idiot lights.

https://youtu.be/9C0Xv9h6HqU

Woooo hooo

, i think voltage spikes are killing the lm2917. I've had to change for a new one a couple of times already. I found this which suggests a different model is required for points.
https://www.electro-tech-online.com/thr ... ic.106247/
If correct, is there an easy way to "dampen" the spikes into it? or do I need to rethink the whole circuit?

warren3200gt wrote::sad , i think voltage spikes are killing the lm2917. I've had to change for a new one a couple of times already. I found this which suggests a different model is required for points.
https://www.electro-tech-online.com/thr ... ic.106247/
If correct, is there an easy way to "dampen" the spikes into it? or do I need to rethink the whole circuit?

Hi Warren, Let me read up on the LM2917 again. Initial thoughts are that ignition type should not kill the I.C. since all you are doing is reading the frequency and Zener DZ1 should shunt out anything over 12volts in anycase.

My concern is that your switch 12v is not stable enough for the circuit, which might explain why the LED read out peaks early when revs increase too rapidly.

The solution would be to add a 9 volt regulator to the supply and change some of the component values to run off 9 volts

Thanks. It would appear that the guy in the electro-tech thread had a similar issue and changing the lm 2917 to the 14 pin version cured this. Although adding in a V regulator and a couple of changes to values of components would be much easier than a circuit redesign!

warren3200gt wrote:Thanks. It would appear that the guy in the electro-tech thread had a similar issue and changing the lm 2917 to the 14 pin version cured this. Although adding in a V regulator and a couple of changes to values of components would be much easier than a circuit redesign!

Leave it with me to digest