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V3 MicroSquirt® - QuickStart Guide

Triggering Directly Off the Coil

Your coil's negative terminal can be used to send the engine speed signal (aka. "the tach signal") to your MicroSquirt® controller. However, you can ONLY do this if you are using your MicroSquirt® controller to adjust the fuel only. If you want to control ignition timing advance as well, you cannot use the coil's negative terminal, and must use a distributor, crank wheel, or cam wheel.

If you are triggering directly off the coil (instead of something like a missing tooth wheel or another relatively low-voltage signal), connect OPTOIN+ (Ampseal pin #30) to the coil's negative terminal, and connect the OPTOIN- (Ampseal pin #31) to a 12V source (rather than grounding it as some older instructions recommend).

This then uses the flyback spike off the coil as a trigger (rather than the 12 Volt signal). Doing this reduces the energy dissipated in the circuit, prevent a thermal 'melt-down' of the components inside your MicroSquirt® controller.

If you have any questions or problems that can't be answered from the links above, or a search the MicroSquirt® manual:

you can ask questions at the MicroSquirt® support forum which is at: Click the links for more information.

MegaSquirt® and MicroSquirt® controllers are experimental devices intended for educational purposes.
MegaSquirt® and MicroSquirt® controllers are not for sale or use on pollution controlled vehicles. Check the laws that apply in your locality to determine if using a V3 MicroSquirt® or MicroSquirt® controller is legal for your application.
©2011 Bruce Bowling and Al Grippo. All rights reserved. V3 MicroSquirt® and MicroSquirt® are registered trademarks. This document is solely for the support of V3 MicroSquirt® boards from Bowling and Grippo.