How Can I Add a Low-Current LED Indicator to My Glo Igniter Circuit?

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For starting glo ignition model aircraft engines, I use an igniter that attaches to the glo plug via wires and a connector. The igniter contains (1) AA NiMH rechargeable battery, 1.2v, 2200 mAh.

I would like to insert an LED or other device in series in the positive lead which would light when either the battery is dead or the coil in the glo plug has failed. It should use an absolute minimum of current so as not to hinder the operation of the glo plug.

If anyone has a suggestion, I would love to hear it. I'm not an engineer, so keep it as simple as possible, thank you.
 
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If the LED must light when the battery is dead, then the LED must have its own power source.

You need to sense when current is flowing. Use a shunt of known resistance and measure the voltage drop across that. Then feed that signal to an inverting amplifier, and use the amplifier output to drive the LED.

If you don't know anything at all about circuit design, then I suggest contacting a local electronics hobbyist to help you. That will be more satisfactory than asking questions on the Internet.
 
livaday said:
light when either the battery is dead or the coil in the glo plug has failed

It would be much easier to make it so that when everything is OK then the light lights since then you have power for a circuit. 1.2V is challenging to work with. Can you use more cells?

BoB
 
livaday said:
For starting glo ignition model aircraft engines, I use an igniter that attaches to the glo plug via wires and a connector
What voltage is the glow plug normally designed to operate from? I would have expected 1.5 volts, which is more than your 1.2 volt cell.
When the leads are not connected to the glow plug, no current will flow, so the light will stay on to indicate an open glow plug circuit.