- Look at the diode in the symbol of your simulation schematic. It is
there for a reason.
- Are those even the same component symbol?
Your ideal current source is your problem in your simulation. You have a thousand volts across RV2 and Q1 is probably in some kind of breakdown.
It also doesn't make sense because your IC1A and and Q1 is also a current source when combined with R1 so you are making two current sources fight each other.
You're not planning to build this are you? Because it is not realistic as it is.
- I'm not sure why you grounded one end of RV2. It seems you want to use it as a
variable resistor, not a divider.
- 1K for RV2 is way too high to push enough current through to
turn on a lightbulb. You would need unreasonable voltages.
- 5V is not enough to turn on the NMOS. Gate threshold voltage is just
when the MOSFET barely starts to turn on. If you are using the NMOS as a switch, you want to turn it all the way on which means you want to use the Vgs
used to obtain the rated RDson which is 10V according to the
But you are using it as a linear device. But that still means the 5V maximum output from your op-amp will still not be enough. In fact, you may need even more than 10V since Vs will rise as more current flows through R1, thereby reducing Vgs if you are applying a gate voltage that is referenced to ground.