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Encoder Interfaced to Xenon Timing Light

mbs2172

Dec 5, 2019
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I have an encoder on a rotating shaft. I want to use the Index pulse (TTL) to trigger an old xenon timing light. I am willing to nip off the inductive sensor to inject a triggering signal. The problem:
First, I'm don't know how much current is induced in the sensor when a plug fires. (Please don't suggest that I measure it -- my cars don't have ignition wires anymore.)
Second, the sensor signal drives the gate of an SCR (MCR100-8). In the off state, the anode, the cathode, and the gate sit at about 350v. I am out of my comfort zone here.
Third, I am a newbie, and please don't hesitate to get very specific. Any advice will be appreciated.
 

Bluejets

Oct 5, 2014
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Is the supply to generate HV for the Xenon separate from the proposed new trigger circuit ?
 

mbs2172

Dec 5, 2019
2
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Dec 5, 2019
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Is the supply to generate HV for the Xenon separate from the proposed new trigger circuit ?
Yes. I will use a corded AC/DC Adapter (12 VDC) in lieu of the car battery to power the timing gun. I don't intend to modify the circuitry inside the gun. I want to remove the gun's inductive sensor that clips onto an ignition wire. The proposed trigger is just a simulated pulse stream from the removed sensor. All custom logic associated with the encoder is housed in a separate chassis with a separate power supply.
 

Bluejets

Oct 5, 2014
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You could use an opto isolator to create an isolation point BUT, this trigger inductive sensor may just be an essential part of the triggering circuit.
If you remove it you might have to build extra circuitry to generate the pulse this inductor is currently producing.
Difficult to say without a complete schematic.
 
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