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logic level tach trigger inputs

Posted: Fri Aug 14, 2009 1:29 pm
by ChaosAD
What is the best way of using an external VR conditioner setup with the microsquirt?

The toyota 4age dizzy pickups can cause a lot of problems with tach resets and ive found a setup that works.
However the mdule doesnt have logic level inputs for the crank and cam pickups.

Will the microsquirt module VR circuits accept a 0-5v logic level input? or would I need to condition the signal to make it pass through 0v?

Re: logic level tach trigger inputs

Posted: Sat Aug 15, 2009 9:13 am
by Bruce Bowling
The CAM VR input (VRIN2) threshold is set to 1.7 volts, this will trigger fine with TTL logic signals.

The CRANK VR input (VRIN1) needs to go thru zero. What you need is the "VR Offsetter" circuit add-on, see:

http://www.microsquirt.com/viewtopic.php?f=87&t=22790

Just be sure to use an open-collector drive on the output of your circuit (like a hall output), if the drive signal is a totem-pole output the circuit will not work. Use a simple transistor to do this, and you can still drive the collector off of +12V if you want.

- Bruce