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8V hall effect source

EFI Wiring Fundamentals

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Discussion and questions related to the course Motorsport Wiring Fundamentals

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Hi all,

I have a differential hall effect sensor that I planned on using for syncing the engine timing. The data sheet calls for drain, 0V, signal, and 8V. Two questions:

1. Is "drain" the same as ground in this case?

2. My ECU (Motec M150) doesn't have an explicit pin for 8V; only 5V, 6.3V, and 12V. What should I do here?

Thanks in advance.

The drain is the shield wire. You should connect that to a chassis ground near the ECU. The sensor may work with the 6.3v power supply from the M150 (you could test this), but I would probably use the 12V.

Thanks David. Is there any harm / unintended consequence to supplying 12V to a sensor that calls for 8V?

If you found the actual underlying spec sheet you would probably find it has a voltage range of like 8-16 or 8 - 24 volts. The reason MoTeC advises the 8V, is because the Gold Box ECU (hundred series) and original dashes had a regulated 8V power supply. So that was the best source of a clean power supply.

Thanks David. The spec says 5+ to 24+ VDC. I tried it with both 6.3 and 12, and they both worked. Thanks for the context on where 8V comes from.

I was able to get this working on the bench; with the M150. For future readers, I enabled the pin pullup on engine sync; which showed a 4V signal. When I pass something mildly magnet (eg, a pair of pliers), the voltage dropped to 0, and then back to 4V; which might explain why the HPA video suggests using 2V as the trigger threshold (the halfway point).

Since you've found that it works with 6.3v, and the spec allows down to 5V, I would use either the 5v or 6.3v supply from the M150 since that is a regulated power supply, vs the 12V vehicle voltage which may have additional noise on it (but normally works fine).

Ah, good point. I switched to a 5V pin, and that also worked. Both the sensor's 0V and 5V are in the same 0V/5V group (A).

Thanks!

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