I was making a circuit that when you power it up with 5V a 5V LED indicator turns on and if you power it up with 12V the 5V LED goes off and the 12V i ndicator goes on.
But... it's not coming on with 5V...
I spiced it, and it doesn't work in simulation either...
if you look at the image on the link
I put a 5.6V zener D1 in the circuit thinking that this Zener would be OFF until I provide it a voltage drop of 5.6V, and since it's in series with so me other stuff (resistors and an LED) I thought it would definitely be off at 5V, but it's on just enough to turn on my FET M1 and not let my D4 LED l ight up... I'm basically measuring a little over 1V at the gate.
I think I can remedy this problem by changing R2 to a lower value... like 1 k maybe, but why is D1 turning on at all? Is it leakage current that's cau sing this circuit not to work at 5V? D3 the 12V LED is definitely off at a 5V supply (as it should be) and the circuit works at 12V... but not at 5V. ..
link is below
much thanks!