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Has anyone recorded an engine startup with oscilloscope quality voltage data? Do we know what these starts in fact look like voltage wise?
I haven't done so in an airplane, but I did sample an engin ...

Bob! It's great to see you posting here again. I'm sure I speak for many here when I say that I was worried about you. I'm very glad to see that you're back in the saddle.

Re the Matronics move, ...

Some regulators like to see a capacitor and some work fine without it. For example, Rotax requires a 22,000μF cap near their regulators, but the installation document for the B&C LR3C...

http ...

Now that the forum is back online, I can report that the second assembly of this project was completed and successfully tested a couple of weeks ago.

Its "+24V_A" and "LO_SNSR" ...

Project update:

Circuit boards and components for Pete's low fuel warning module arrived and I built up a prototype. It behaved strangely when powered with 14V and didn't work at all when powered ...

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For those following this thread, an update: Several emails have been exchanged between Pete, Joe and myself. I've finished a circuit board layout (see attached image; dimensions in inches), which I' ...

After thinking about it, one could accomplish the same thing without installing a momentary push button switch by pulling the circuit breaker for the fuel level switches and then resetting it, assumin ...

The HPFS can stay open in Auto. It just needs to be closed in the off position.
In that case, Joe's schematic has you covered. His design should be easy to wire "in the air" using a chassi ...

I haven't gotten back to working on this but I wanted to check progress here. It looks like Joe has the basic switching schematic pretty much licked. Except...

As drawn, the HPFS is only under ma ...

Joe: Yep, I was over-thinking it. Well done. Your second diagram does exactly what's needed with nothing but one relay per side. You have to wonder why they used a PLC in the first place.

Pete: ...

Pete, do you have a datasheet link for your LPFS and HPFS? I'd like to see their electrical requirements and what position feedback, if any, they offer.

Yes, latching relays could definitely be pa ...

Here's a quick conceptual doodle showing how the switch wiring might be done to handle OFF-MANUAL-AUTO switching, using a 2TL1-1 (or, for a much cheaper alternative, the B&C S700-2-1).

Switched ...

OK, the 2TL1-1 is a standard DPDT ON-OFF-ON switch.

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You're not kidding about the wiring harness documents being cryptic! They'll take some effort to figure out.

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It looks like ...

Joe, that looks like what I had in my head after this discussion.

For those following along, the Honeywell 2TL1-10 (MS27407-4) is a DPDT ON-ON-ON switch. See the attached screen-grab from the data ...

OK, great.

Regarding the switches, I'm assuming they're SPDT toggles; if not, what are they? Can you describe how they're wired? Are all three terminals connected to the PLC, or is the common (mi ...

A few more questions:

1. With a vented main tank, can we assume that even in MANUAL mode, the Main Tank High Level sensor should close the LPFSs to prevent main tank over-filling and fuel loss via ...

In the original post, the device in question was described as a 'continuous' solenoid.

Is that relevant, or am I just being pedantic?
The primary difference between continuous and intermittent dut ...

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Aaah, OK. That makes sense now; thanks. I'm glad you found a definite cause for the problem and got it solved!