DIYEFI.org Forum

i`m think it`s a signal inversion for msd trigger adapter.

This is in fact not an inverter, more likely a level converter or simply a current amplifier as the MSD has a rather strong pullup on the white wire, intended for use with points.

Fairly typical darlington pair current amplifier isn't it? :-)

I'm curious how many have been slapped because they were looking under the hood (or bonnet) of thier significant others, and blurted out "nice darlington pair"

hmm... soon i`m get a 2 ch osscilogaph and try check how honda ecu use igniter unit. i`know what stock igniter unit control dwell and give a feedback to ecu (because ecu knows shoot spark or not).

ECU drags that voltage down to 0V to send the signal for coil charging.
good. soon i`m made some mod for my prelude ecu

Fred wrote:Fairly typical darlington pair current amplifier isn't it?

Not so, a darlington pair uses one transistor to amplify the base current of the other in a common collector connection. This circuit is two inverting (common emitter) amplifiers in series.

red line first cyl sensor. blue-ignition output signal. it`s uses npn transistor for signal output.