Goodmorning,


I'm trying to light up a led with an old light barrier I still have around. I want the led to light up when someone passed the barrier. Unfortunately I have a 24v signal when the barrier is safe and when someone walks through it, the voltage drops to 0.


I still have some mosfets around but I’m not sure how to tackle this problem. I know I could use relay’s but I do not really have space for one. I have some mosfets and resistors so that shouldn’t be much of a problem.


Long story short: I’d like to make a 24v circuit with mosfets. When there is no signal my led should light up.


Is there a simple way to do it?

 

I call it a double invert circuit.

 

Based on your reply i've made this drawing. Would this work?

 

No. You need a p-channel to do a second invert. What you have there is 2 n-channel transistors, normally on, in series.

 

Dear #12

If its not to much to ask; could you make a drawing for me?