Circuit sketches and simulations on web browser

[tmuikku]

Saw a link for this handy looking app that works on browser.  https://www.circuitlab.com/

Tried it quickly and seems like you cannot add components but there are plenty available for basic stuff already. Faster to use than windows paint to post small schematics for people here in forum

 

[ruffrecords]

Seems quite easy to use. Pity there are no tubes.

Cheers

Ian

 

[gemini86]

Reminds me of an android app called everycircuit... I tried simulating the helios 2128 line card (3 transistors) and it couldn't figure it out... I wonder how much better this software is.

 

[AMZ-FX]

I tested it out with a simple transistor circuit and it worked fine, but failed on my next try with a more complicated jfet design.

regards, Jack

 

[PRR]

> failed on my next try with a more complicated jfet design.

I put up a simple JFET, did DC and TRAN analysis fine, but refuses to do a Frequency response, P matrix is singular (which is not a proper error message).

Yet I took their sample Electret Mic circuit and it ran fine. Fine except the freq resp goes past 100GHz! There's no capacitance on their JFET drain. Tossed 200pFd where a cable would go and got a reasonable ~~100KHz corner.

I suppose I could hack their sample until it stops working, figure out where the problem is.

 

[PiraxaStudios]

I've been using EveryCircuit to try and figure out simulating various audio circuits. One thing it doesn't seem to grasp is opamp feedback routed to the negative input, when an AC signal is going into the positive input. Not sure if anyone's found a way around this?

Pictured below: an AC signal of 1V amplitude is sent to an opamp in the +ive input. Despite a resistor of 1kΩ being used as a gain trim pot, the opamp output still reads 1V, perfectly in phase with the AC signal. No amount of changing the resistor value changes the output voltage

 

[Brian Roth]

That opamp circuit is a UNITY gain, non inverting circuit. To adjust the gain in that circuit, you need another resistor going from the non inverting input to "ground".

Bri

 

[PiraxaStudios]

Thanks Bri! I'm a bit confused on why this works the way it does - Are there any PDFs lurking around that explains the various uses of opamps? I think I understand how they work when the input signal goes into the negative input

That opamp circuit is a UNITY gain, non inverting circuit. To adjust the gain in that circuit, you need another resistor going from the non inverting input to "ground".

Bri

 

[Brian Roth]

See if you can find any of Walter Jung's books/articles. His explanations are pretty easy to follow. One of his classics is the book "Opamp Cookbook".

Bri

 

[PiraxaStudios]

See if you can find any of Walter Jung's books/articles. His explanations are pretty easy to follow. One of his classics is the book "Opamp Cookbook".

Bri

Amazing, thank you! Do you happen to know anything I can read that explains loads and input/output impedance? I had another thread on this, which exploded and then got off topic...