search

sharpie7 / circuitjs1

Electronic Circuit Simulator in the Browser
GNU General Public License v2.0
2.31k stars 636 forks source link

Feature Request: Additional op amp paremters (slew etc.) #330

Open Exaeta opened 5 years ago

Exaeta commented 5 years ago

I would like to request more realistic OP amps..

Real op amps have a number of features that make the simulator less than realistic... In real circuits, you usually need a bypass capacitor, because of the current draw from the + and - pins. The following things would be helpful:

Option to enable + and - pins Ability to set slew rate Ability to set GBP Ability to set common mode range Ability to enable non-zero input bias current Ability to set minimum and maximum output voltages relative to Vcc and Vee. Ability to set maximum source and sink current on op amp output.

pfalstad commented 5 years ago

https://github.com/sharpie7/circuitjs1/issues/331#issuecomment-489392306

ormaaj asked: "Is the 741 sufficient as a representative op-amp model? Yeah it's often used for illustration due to its historical significance and "simple" 3-stage bipolar design."

Good question. I can easily adjust the output current and slew rate. But the 741 isn't rail to rail. Another op-amp model might be better, if it's simple. The 741 is complicated enough as it is.

I found an LM324 model that is actually less complicated, and it gets closer to the rails, so maybe I'll use that?

Exaeta commented 5 years ago

I was thinking a slew rate and relative rail limit would be a good improvement, since it allows you to get a semi-accurate estimate of what would happen for a wide variety of op amps.

So how about a "select op amp" which has several, plus a custom option which allows you to set these parameters customly, instead of using a more realistic model. That way you have an ultra realistic model for certain op amps and a more ideal one for whatever you happen to use.