RE: DX8 telemetry RPM pickup for Gas engines - SOLVED!!
WOW, I've never heard of something like that! Amazing recovery - the chips in the receivers are only able to work to 3.3V, so I doubt the innermost regulator failed.
The TM1000 does not include any isolation circuitry. If you connect to your ignition system, you are providing a direct connection from the ignition to your receiver. We provide magnetic sensors to make that unnecessary.
We have had one or two reports of people who had the spark plug lead close to the TM1000 and it DID cause issues for them. There was no electrical connection, but apparently the long wires to the TM1000 and the unshielded plug wire didn't like each other very much. He solved his problem by relocating the TM1000.
If we had an interface to the ignition circuit, it would mean we had done extensive testing in that configuration (we have guys like Seth, QQ, and McConville to fly them). I have to recommend sticking with a system we have.
That said, as a modeler and "tinkerer" myself, I don't have any problem with what you and Franco have done. I just can't give a "Spektrum approved this" sticker to you.
Andy