Hi all,
I am trying to simulate a circuit at https://elonics.org/adjustable-auto-on-off-delay-timer-circuit-using-555/ for delay timer in NE 555.
I have replaced the switch with a mosfet, however I don't get the correct output . I have attached my LT Spice file below. I am not sure what I am doing wrong

Thank you

 

You have a short circuit between the source and drain of the MOSFET.

 

You have a short circuit between the source and drain of the MOSFET.

It is suppose to be shorted (acts as a switch just like in diagram)

 

It is suppose to be shorted (acts as a switch just like in diagram)

Surely the pulse generator is supposed to switch the MOSFET on and off. It can't do that with the short there.

 

It is suppose to be shorted (acts as a switch just like in diagram)

No, it isn't.

It is supposed to be turned on and off by V2 to simulate the switch in the diagram. You have a dead short wired across it, so it does nothing after the first timing cycle when power is applied.

ak

 

I don't get the correct output

This tells us nothing.

What output are you expecting? What is the circuit supposed to do?

What output are you seeing?

Please post the simulation plots.

ak

 

Surely the pulse generator is supposed to switch the MOSFET on and off. It can't do that with the short there.

Problem solved people. It turns out that I am blind

 

No, it isn't.

It is supposed to be turned on and off by V2 to simulate the switch in the diagram. You have a dead short wired across it, so it does nothing after the first timing cycle when power is applied.

ak

Sorry my eye was blind that time