Is there a transistor that can switch on with only a 6 milivolt pulse?

Question

I have a VR sensor on an old engine, but the output at starting speed is only 2-6 millivolts. I'm trying to get an electronic ignition to read this signal but it needs at least 600 mVs. It can handle up to 50 volts. Is there a transistor that can switch to on with something as small as 2 - 6 milivolts? The engine electrical system is a standard 12 volt system, but the signal generated by the crank sensor is AC. I can use a diode if the transistor can't handle AC current.

What can I use to amplify a 6 mV AC signal to at least volts 600 mV on a 12 V system (Up to 50 is OK)

Answer 1

You need an operational amplifier, such as a TLC274 available from DigiKey.com. You need to wire it as an AC coupled amplifier with a gain of 100, using the appropriate circuit in the app note. I choose this part because it will work from a single ended 12V supply, and is robust enough for an automotive application.