Questions tagged [falstad]
An online, open-source circuit simulator
36
questions
3
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1
answer
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Unable to get my astable multi-vibrator working in LTspice
I'm trying to build a basic square wave oscillator using an astable vibrator made with an op-amp for my Intro to Circuits class.
Unfortunately, I cannot get LTspice to simulate the oscillations.
I've ...
- 33
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0
answers
34
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Circuit simulation of PWM has a rapid loss of voltage in Falstad
I made a PMW in falstad that works only for a few seconds bevor the voltage in whole circuit drops to zero. I already tried to redirect the diodes with no effect.
https://www.falstad.com/circuit/...
- 1
0
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3
answers
99
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What is the origin of negative offset in this amplifier circuit?
I'm working on a class AB power amplifier for a school project. The desired specifications are a load impedance of 4-16 Ohms, 1% Total Harmonic Distortion (THD), and 10W amplification.
The input ...
- 75
0
votes
1
answer
63
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Phase shift in clamper circuit
I'm trying to simulate this clamper circuit in falstad:
But there's a phase shift in the output voltage of my circuit. Is this expected? Am I doing something wrong?
Can someone please explain?
(I'm ...
- 107
0
votes
0
answers
58
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Avalanche effect of a Zener diode, or simulator bug?
On the Falstad simulator, I tried to illustrate the phenomenon of the avalanche effect of Zener diodes. I've added a capacitor to remove the DC component, too.
However, I'm not sure that the (very low)...
- 1
1
vote
1
answer
73
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Falstad Schmitt trigger problem
In the given problem, I know that the answer should be (d), because it should act like a Schmitt trigger.
But when I try to model this circuit in Flastad, I suddenly get that the answer (b) is right.
...
- 33
0
votes
1
answer
75
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555 IC 1 minute delay timer not working in simulator
I have a problem in Falstad that when making a 555 IC based signal delayer that should delay a power-off of a certain device, that the whole circuit behaves really weird and doesn't work as stated by ...
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2
votes
1
answer
69
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Finding Ve for a 3 input AND gate TTL circuit for different logic combinations
I'm designing a circuit that takes 3 24V input signals and pulls a 50 ohm resistor to ground when all three signals are high. My main concern is the voltages across different pins of the transistors ...
0
votes
1
answer
78
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How do I make a good frequency multiplier for a basic sound chip? It uses a DAC, so it needs a high input frequency for lower output frequency
I'm building a simple triangle-wave sound chip based around a 4-bit DAC. It works, but I have to have each individual square wave for each of the 16 notes (which are bass-range, 60Hz-238Hz.) I want to ...
- 5
0
votes
2
answers
185
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High-current transients with LM317 LD driver in Falstad
I have been building a laser diode driver in Falstad, but for the first 200 μs there is a current spike of over 70 A! This would mean instant death for my laser diode.
If you are curious the laser ...
2
votes
0
answers
109
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Is there a way to approximate an optotriac in CircuitJS / Falstad?
Falstad does not have an optotriac part. I've opened a feature request issue on the CircuitJS GitHub to ask for one to be added, but is there a reasonable way to emulate an optotriac given the ...
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votes
1
answer
242
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Turn an LED on/off LED with a flip-flop counter [closed]
I want to make a 7x7 LED matrix which begins to turn on the first one LED to the last and then turns off the way back (spiral matrix.) I'm trying to turn the LEDs on/off by using signal created by ...
1
vote
0
answers
204
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Falstad, Micro-Cap, LTspice
I've just started with Electronics and am enjoying the Falstad simulator for seeing how components work, current flows, etc; really great.
I've become aware of Micro-Cap and was aware of LTspice as, ...
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1
vote
2
answers
2k
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Falstad Circuit not running
I created this Falstad circuit that is supposed to run to toggle between the 3 circuits to power the LED. The top AND gate leads to a circuit that makes a strobe light effect. The second is supposed ...
- 11
-1
votes
3
answers
255
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simulation (in Falstad's app) of thyristor using transistors fails
I am trying to simulate thyristor behavior with transistors PNP and NPN but it fails (is it a bug of app?). When lower switch is open(and was never closed) and upper closed then current flows through &...
- 107
2
votes
1
answer
1k
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How to simulate external voltage source in Falstad?
I am looking to simulate circuits on Falstad: http://www.falstad.com/circuit/circuitjs.html . One of the features on the website is the ability to add an external voltage source programmable with ...
1
vote
1
answer
542
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DC current through capacitor in Falstad
I am using the Falstad simulator.
I do not understand why am I getting a DC current through a capacitor in simulation.
This must be an error from the simulator. Please, let me know if I am sane, I ...
- 277
3
votes
2
answers
817
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Is this component in falstad a tl431
I'm self studying electronics, I am now familiarizing myself with the tl431, which is pretty much a "variable zener" aparently.
I was shown the following symbol.
I would like to simulate ...
- 543
2
votes
1
answer
977
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Hold-on-hold-off soft latch power switch circuit
I'm trying to make a "hold-on-hold-off" type soft latch switch circuit, but I'm having a little trouble. I've found tons of "press-on-hold-off" types, but I haven't been able to ...
- 413
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votes
2
answers
639
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Falstad - a bug with mosfets?
I have a schematic in Falstad. It is almost symmetrical (the mosfets are connected by drains and "SWAP D/S" is enable in the second mosfet to be able to connect both).
And this symmetrical ...
0
votes
1
answer
73
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I want to do make an and-gate but why do I get high when my swich is off?
I want to do make an and-gate but why do I get high when my swich is off?
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1
answer
266
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"Noise" in simulator
I have been working on a simple circuit which performs XOR operation.
The problem is that I am seeing a noise-like graph when both inputs are set to 1 (5V) and I have been doing a research on what it ...
0
votes
1
answer
314
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BJT differential amplifier with active load
I completed the theoretical parts of the DC and AC analysis. I want to test them with the simulator. Both DC and AC analysis failed.
I killed DC sources in the AC analysis section and I short-...
2
votes
2
answers
416
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Falstads circuit simulator : capacitors have initial voltage?
I started playing with Paul Falstad's circuit simulator applet to see if it would be useful for my intro physics students. However, I'm running into a quirk regarding capacitors which I don't really ...
- 121
3
votes
1
answer
1k
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Circuit simulates in Falstad but not in LTspice
I'm having trouble simulating what should be a simple circuit in LTspice. I am designing a simple PWM-regulated power supply, but I'm running into problems when I try to simulate it.
When I simulate ...
- 153
1
vote
1
answer
166
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Diode letting voltage through in circuit simulator - bug or real?
I'm pretty new to electronics, and so I've been modelling my circuits in a Falstad's circuit simulator.
I noticed something which I did not expect, and am curious - is this effect real, or is this a ...
- 496
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votes
1
answer
122
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Beginner - Why do voltage/current behave this way
I was checking falstad and came around this resistor circuit which lost me completely :
Knowing that input voltage is 5v and current is 17mA :
1- Why is the voltage 0 after the 200Ohm resistor ...
- 147
2
votes
1
answer
1k
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Attempting an audio pre-amplifier circuit with falstad.com
I'm new to electronics and discovered the falstad.com simulator. I wanted to model this audio pre-amplifier circuit:
So I went into falstad and drew this:
My pre-amplifier circuit on falstad
The ...
- 435
3
votes
2
answers
2k
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Piezo speaker equivalent for circuit simulator
I am using Falstad's circuit simulator to test a design of an Op-Amp based microphone-speaker system...kind of like a megaphone, but the speaker is going to be a piezo plate. Falstad does not have a ...
- 199
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1
answer
2k
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How to Plot X/Y in Java Circuit Simulator
Does anyone know how to select the Y variable when doing an X/Y Plot in Java Circuit Simulator? I tried many things and none have worked.
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1
answer
2k
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Kill Switch schematic
I want to make a kill-switch pedal with on/off LEDs for my guitar. I tested a simple schematic but every time I ground the circuit like the schematic i put below i get an error:
voltage source/...
- 105
2
votes
1
answer
2k
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How To Charge a Battery in Falstad Circuit?
I'd like to model the charging of a battery in Paul Falstad's Circuit simulator. But, i cannot find a battery component.
Is there any way to do this?
thx
- 166
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vote
2
answers
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Active Notch Filter Simulation
I need to build an Active twin- notch filter that will filter out 60Hz. I am following the schematic bellow:
To test the schematic, I am simulating it on Falstad Circuit Simulator, but the 60Hz is ...
- 198
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votes
2
answers
115
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OP Amp - Finding currents [closed]
I am having some difficulty figuring out V_out. I know that it is going to be inverted because V+ = 0 and I know that V- ≠ 0. I don't really know how to go about finding the currents in the system to ...
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votes
4
answers
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Is there a more realistic circuit simulator than Falstad's?
In real life, the 100mA load in the circuit below will experience a brief, partial loss in current and and a drop in voltage when the 4A load is engaged but this simulator is too basic to show that. I ...
1
vote
2
answers
1k
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Why isn't this Elenco circuit working in Falstad's simulator?
I'm learning electronics engineering with the Elenco 130-in-1 kit, and I'm trying to get better at visualizing how these circuits are working by making them in the Falstad simulator, but the first one ...
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