RPM Reader w/ Tachometer.. Help Required!

fireworks1 said:

I am starting to concede defeat

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ericgibbs said:

hi,
As the guys have just pointed out the circuit looks wrong.

I'll look it over and get back to you. Can you confirm that you are using a ZD1901 interrupter or some other device.???

Whats with the defeat attitude, if you follow what we say, together we can most likely sort it out..

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fireworks1 said:

Thanks so much Eric, honestly.
The defeated attitude is because I have one week to get this
complete and I don't want to waste peoples on this forums time.

And I also believe that there is something wrong with
the circuit that is why I looked for outside help instead of
being told "that schematic should work".

I hope you are able to help...

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ericgibbs said:

OK,
If you listen and learn, you are not wasting our time, we are here because we want to help.

Look at this circuit, its yours with minor changes.

The image you see of the tacho signal is from the LTspice simulation of your circuit in action.

If in doubt, ask.

EDIT: I have used the BC547 and BC557 because of the simulation, the BC548 and BC558 are OK...

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fireworks1 said:

The changes are so simple..
What was the output signal like with the current circuit?

Thanks soo much...

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ericgibbs said:

hi,
You didnt mark on the circuit where you had taken the tacho signal from.??? unless it was +12V.!!!

Look at this extract from the ZD1901 d/s.... this is the way I read it.

I hope you have not damaged the opto, check the wiring.!

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