I would like to use a MOSFET as a switch in a circuit but I can't find any with a threshold voltage of 10v or 12v. Why is this uncommon?
As information, There is less than 1mA needed to go through it. I just don't want it on if its less than 10V on the gate.
Almost everything I see has a Vgs(th) of 1-4 volts.
EDIT*** Here is my circuit
I'm trying to delay the voltage to the gate by 2ms or more so that the LED won't light for that amount of time.
Best Answer
Just use a resistor potential divider circuit or even one with a zener in series with the gate. The zener voltage will have to be exceeded before any significant voltage is attained on the gate. If using a zener it's best to assume low impedances to drive the gate. For instance a 10V zener and a FET with 1V threshold would likely need something like 10k across the gate to ensure zener leakage currents don't create a "false" gate voltage due to high impedances.