I'm a little confused about whether transistors use voltage or current to control the amount of current though the drain/source. I'm reading a book that gave the formula: beta = Ic/Ib That seem to me that current is controlling it, but when I tried with a n-channel MOSFET(2n7000). First I used two D batteries in series to get 3V and about 25mA. I used a direct connection to the gate and it wouldn't drive a LED. So I tried a 9V batter(but really at 7.9V) with about 18mA and it would drive the LED.
This makes me believe that the voltage is what controls it. Can someone clear this up for me.
This makes me believe that the voltage is what controls it. Can someone clear this up for me.