# Questions tagged [circuitlab]

CircuitLab is a browser-based schematic and circuit simulation application.

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### How to simulate series capacitors in CircuitLab?

I am reading through the book Practical Electronics for Inventors, specifically the section on capacitors. I read that capacitors in series will an have equivalent capacitance C with formula  C=(1/...
• 21
1 vote
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### Circuitlab - How can I create my own transistor model?

I would like to create some transistors, like the S8050 transistor, for to use in CircuitLab. What I found is https://www.circuitlab.com/docs/custom-device-models/ If I open another existing ...
• 141
65 views

### CircuitLab DC parameter sweep problem circuit

The following circuit, taken from this answer seems to give odd results when doing a parameter sweep simulation on CircuitLab. Is the problem with CircuitLab, or is there some problem with the circuit ...
• 13.3k
67 views

### Simulation Error in Circuit Lab with 2 Dependent Sources

simulate this circuit – Schematic created using CircuitLab I'm practicing some problems and came across this circuit. It asks for the Thevenin equivalent with respect to terminals A and B. I ...
141 views

### Why is CircuitLab so slow to simulate this simple circuit? (Op Amp DC-coupled to BJT phase splitter.)

Not sure how much is known or published about the back end of CircuitLab, but: While simulating a different circuit, I noticed very long simulation time. I narrowed the culprit down to the below ...
• 1,674
1 vote
73 views

### Plot Z vs Freq for RL-C circuit

I am trying to simulate the resonance frequency of an Antenna, that can be modeled by a resistor in series with an inductor , both in parallel with a capacitor: By attaching the antenna to a AC ...
• 251
69 views

### How can I set the maximum current in my CircuitLab circuit?

I have designed a circuit for two electromagnets to be turned on and off by a Raspberry Pi, but the total current draw by the circuit is 10.99A and my power pack has a limit of 2A. How can I simulate ...
85 views

### Difficulty using CircuitLab to build a Zener Diode Voltage Regulator Circuit

So I'm trying to build a Zener Diode Voltage Regulator in CircuitLab. I've been searching around Google for some insight into building these, however, I'm required to use a triangle wave input, ...
1 vote
68 views

### CircuitLab with fixed frequency

Inspired by this SE question, I was wondering how good CircuitLab would be a solving this type of problem. Why do we not include the current source when finding the Thévenin equivalent impedance?...
• 10.2k
171 views

### How do I do calculation in CircuitLab? How do I provide +Vcc and -Vcc to the OpAmp?

Here is my simple circuit. I would like to test whether the output is correct as per manual calculation. According to manual calculation, Gain=3.1, Vo=10.54V. My question are: How do I do that ...
1 vote
142 views

### CircuitLab simulation of 555 timer - OUT HIGH always delivering 5V irrespective of Vcc?

I've scratched together a design for a 555 timer based driver for an IR540 MOSFET. But in CircuitLab the simulator shows the 555's OUT voltage is always 5V when high, for Vcc ranges 3.3V through 24V. ...
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### How to achive mutual inductance and CM choke simulation in CircuitLab?

This site is using CircuitLab. In some SPICE programs it is possible to simulate CM choke. For example: Mutual Inductance is designated in a SPICE netlist by beginning the first word (label) of a ...
• 1,275
1k views

### Modeling impedance matching network

Background I'm looking at the RF (LNA_IN) pin of ESP32 as described in esp32_hardware_design_guidelines. According to this document, the output impedance of the RF pins of ESP32 are (30+j10) or (35+...
• 462
66 views

### Simulating the discharge of a condenser using CircuitLab

Intro: While studying for a Signals and Systems exams for tomorrow i decided to simulate an exercise and prove my answers are right. simulate this circuit – Schematic created using CircuitLab ...
• 105
1 vote
472 views

### How can I add variable duty cycle PWM to a CircuitLab simulation within a question?

This is my first attempt to simulate a circuit in the time domain with CircuitLab. In order to ask a proper question about something similar driven with PWM, I'd like to add an adjustable duty cycle ...
• 3,621
1 vote
4k views

### Battery charging circuit

Can anyone assist me with correcting this circuit? I'm trying to build a 12 V lead acid battery charger that would have a green LED indicator when charging and a red LED indicator when fully charged. ...
4k views

### How do I use Circuit Lab to show me Voltage and current information on this circuit?

I have a bunch of red LEDs, I don't have their data sheet and I am trying to figure out a safe resistor to use to lower the current across them safely. My current setup is as follows: simulate this ...
• 444
1 vote
6k views

### Voltage Clipping with Two Series-Opposing Zener Diodes

Theory Schematic for Voltage Clipping with Two Series-Opposing / Bidirectional Zener Diodes Consider the following schematic for voltage clipping with two series-opposing/bidirectional Zener Diodes \...
• 211
2k views

### Single-supply op-amp behavior with 0V input

I am confused by how op-amps work. I have a single-supply op-amp: the power rails are +5V and ground. The circuit in the image says the op-amp is an LM741 but it's actually the op-amp built into the ...
• 1,157
1 vote
174 views

### PhotoMOS simulation circuit

I want to simulate the following PhotoMos in CircuitLab for switching circuit but i didn't find the model for any photomos in CircuitLab. I was preparing a simulation for a switching MOSFET circuit ...
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