Thread: How can I change a negative charge into a positive charge?

I have a photo gate sensor that gives out a negative pulse, and I have a binary counter it goes into that only counts positive pulses. How can I change it into a positive pulse? I'm using a bread board so I can get the charges, is there any way to do it with transistors?

You can't change charge from negative to positive, or vice-versa.

But you can change a negative pulse to a positive pulse with a simple transistor inverter. Or rearrange the photo sensor to put out a positive pulse.

When you say negative I am guessing you mean that the the output is normally high and it is a low output. I don't see why anyone would bother to make one that actually goes negative. Anyway, you do this with an inverting stage. One transistor in common emitter configuration will do the trick.

The circuit that does this is called an inverter circuit. Using transistors, just make a common emitter amplifier, and it will do it.