I can't seem to get anyone from MoTeC UK support to help me on this, so I thought I might have better luck here:
I'm having someone make a transmit modem / computer interface (clock generator) based on the MoTeC circuit posted on another thread here recently. I've no idea about the technical side of this, but the questions are really do you need a power supply for this unit, or does it pick up from the ecu somehow?
And :" Okay, I've designed the board assuming there's no PSU required; it's quite small (about 60x40mm) - however, I have come to the conclusion that the 74HC151 isn't really needed.
When I'd initially looked at the schematic (thanks for the higher resolution version - there were some numbers I wasn't 100% sure of, although I'd guessed correctly), I thought that it was able to select one of two frequencies, either generated by the inputs I0 or I3 depending on whether pin 1 is high or low.
I'd missed the fact that pin 1 is actually the power, so it's always high.
This means that I3 is always selected, and this is just selecting a 153.6KHz clock to output on pin 8.
This means that pin 8 could be generated by the 74HC4060 directly from the Q5 clock.
Or, it could be DRASTICALLY simplified by using a programmable divider - and one happens to exist at the right frequency.
Could you check with MoTeC if it's just a conditioned 153.6KHz signal that's required on pin 8, please? If so, then the design can be simplified and it would be easier to wire up. (The signal conditioning is done with R3 and C5, which I believe I'd need to replicate).
Thanks