low-fi circuit simulation

I often want to play with some circuit or other, and am not sure if it will work.

For those of us who aren’t super strong on electronics theory, this means either we buy a bunch of parts and test it out, possibly frying them, etc OR do some sort of simulator. Unfortunately most simulators are somewhat complex (spice, etc)

I was pointed to a really nice java simulator that is online for free:
http://www.falstad.com/circuit/e-index.html

He has lots of examples, and you can edit the circuits yourself, add parts etc. I have learned a lot there.

For example, here’s how to simulate my DC motor speed control circuit:
1) go to http://www.falstad.com/circuit/e-ohms.html
2) right click in the black after java loads, and select file->import
3) paste in the following:

$ 1 5.0E-6 3.9121283998153213 53 5.0 50
R 112 224 64 224 0 2 400.0 2.5 2.5 0.0 0.5
g 320 256 320 272 0
d 208 128 208 192 1 0.3
t 176 112 208 112 0 1 -11.855891688647894 -0.016674669651078056 100.0
w 176 160 176 112 0
w 176 112 176 96 0
r 176 96 176 48 0 1200.0
R 176 48 128 48 0 0 40.0 12.0 0.0 0.0 0.5
w 176 48 208 48 0
w 208 48 208 96 0
w 208 128 272 128 0
f 272 128 320 128 0 1.5
w 320 144 320 256 0
w 208 48 320 48 0
f 176 224 208 224 0 1.5
l 320 112 320 48 0 4.0E-5 7.833859394512643E-8
w 320 48 384 48 0
w 320 112 384 112 0
d 384 112 384 48 1 0.805904783
r 384 48 432 48 0 2700.0
w 384 112 432 112 0
d 432 48 432 112 1 0.805904783
x 447 73 480 77 0 18 LED
x 266 167 355 171 0 18 Power FET
x 255 86 308 90 0 18 motor
I 112 224 160 224 0 0.5
w 160 224 176 224 0
x 7 260 111 264 0 18 PWM source
w 176 160 176 192 0
w 176 192 208 192 0
w 208 192 208 208 0
g 208 240 208 272 0
x 62 119 155 123 0 18 gate driver
x 345 136 470 140 0 18 flywheel diode

that’s it! pretty neat, huh?

You can easily make your own by doing file->import with a blank value, then right-click and add parts as you like. File->export will show the config you should save as a txt file if you want to save the circuit or come back later.

You can also copy the java class locally and run it without an internet connection. He updates it from time to time, so check back for new parts and features.

He also has some physics simulators which i haven’t tried, but are probably good, given the high-quality of his electronics site.

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One Response to “low-fi circuit simulation”

  1. […] Fighting with technology Freely you have received, freely give « low-fi circuit simulation […]

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