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transistor selection

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BioniC187

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Hi all,

Need a bit of help from those with lots of experience with transistors.

Firstly, this is what I am doing:
I want to measure the duty cycle of my cars fuel injector system.

So I am wondering what would be best - A PNP or a p type fet?

Suggest some model numbers for the job :)

I have a bc327 set up at the moment. I also have a diode running from the base to ground. I am a bit paranoid - considering the transistor could breakdown, and then pull the injector to ground all the time - It has happened to me before
 
Why do you need a transistor to "measure the duty cycle of my cars fuel injector system"?

A circuit would help explain what you are trying to do...
 
A cars fuel injector is like the coil of a relay connected with an npn transistor.

12V gets put on one end of the fuel injector, and the other gets pulled to ground.

I need to sample the pull to ground leg to measure the duty cycle.

I also need to make the sample a 5V signal.

I prefer to use a transistor instead of a voltage divider to get it to a 5V signal
 
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