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Location:
Brisbane
Registered:
May 2002
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 Tachometer Operation/Waveforms
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Sat, 03 September 2005 14:06
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Hey guys, trying to sort out the tacho in the 1jz/jza61.
I need some information on tachometers and how they work! (and if anyone gets their 'search natzi' hat out I will bitch slap you  ).
Tachometers usually get their signal from the coil -ve (this I know).
I figure that the tachometer must use the high voltage spike (EMF) that is generated due to the large inductance (coil) suddenly being GND triggered via the ECU? (is this correct?).
I've tried that coil emulator circuit floating around, which really should work as it just does the exact same thing on a smaller scale! (I tested it using a function generator and a CRO so it appears to work).
My main question is, does anyone have waveforms of what tacho outputs look like (so I know what I am trying to replicate)? And does anyone know what voltage (of the spike if my understanding is correct) is required to trigger the tacho?
At any rate I think I will acquire my CRO tomorrow and see what is going on!
Cheers
Wilbo
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