My 'frrebie' PSPICE hasn't got one - I'm using their generic opamp .
But the 358 is pretty slow, so I'd expect a faster model to show instabilty worse.
Try adding 10n from 358 output to - input to slow it even more.
Must get LTSPICE.
Allan
Rethink.
The OP effectively wants a pressure regulator. There are many mechanical devices based on diaphrams which do this well as previously mentioned.
But if he wants to do it using this controllable 'leaky valve' , a pressure sensor and a simple bit of analog electronics would work fine.
Allan.
Agreed. Arduino is probably not the best or easiest approach to the OP's goal.
Thanks for the suggestions re the simulation, but neither the addition of a feedback cap, nor switching to the universal opamp in LTSpice eliminated the oscillation. So, I can't blame the LM358 model.
I don't believe the simulation, but then in real life, op amp circuits do oscillate at the most inconvenient times!
Bob Pease had rude woirds to say about PSPICE and it's ilk - and I rather agree.
The only true simulation is a breadboard and some common sense.
A variant of this from an old boss of mine when I was designing pagers at Philips :
'Simulation is like masturbation - do too much and you get to believe it's the real thing'
Allan
Simulation is like masturbation - do too much and you get to believe it's the real thing'
Interesting . Very funny. Makes sense.
The PhD EE at my last job had a $60,000 simulation program he used to check his designs.
All I can say is they always worked when I built them.
jremington:
The design in the data sheet is surprisingly bad, for a couple of reasons, one of which is the missing flyback diode.Obviously, the coil should not be in the feedback loop.
I am also wondering about that. that would destroy the tip120 because the base voltage would be too high. or is there some other reasoning for that?
What does R2 do ?