TIM rev counter

[tom70]

Does anyone know if the TIM rev counter need a 5v or 12v pull up for the rev signal ?

My rev counter didn't come with an instruction.

Cheers

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Is it meant to be connected to the coil '-' ?
If so 12v will be okay.  I'd take a 1K resistor inline with the tacho signal in, and bounce the open end off the + terminal of the battery.

I can't understand why the diodes arent giving the right signal for you?

[dnb]

If it's supposed to go to a coil -ve, then the counter may well be expecting a high voltage (ie 350v or more) signal caused as the magnetic field breaks down.  In this case, the voltage must be duplicated with an inductive pullup - naturally, diode protection should be used to protect the ECU.

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In that case the 18V zener diode is reducing the voltage too much for the rev counter.

[tom70]

Thanks for the help here.

I have no idea why the diode don't work, the rev counter is just not responding.

Talking about pull up, which of the following connection is correct?

Option 1:


Option 2:



Sorry about my lack of electronic understanding.

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Option 2.

When P259 channel is closed the tacho gets 12v, when the channel is open the voltage drops to zero.

Rob