LED Circuit From Magnet Video

I have had a few requests for the LED circuit used in my magnet video. I’m excited to see people wanting to build the circuit! The same concept is used in those shake flashlights.

The circuit is really not too difficult. The important thing is that you will need a spool of magnet wire with a LOT of turns. There was no scientific method to the number of wire turns needed. I just bought a spool of magnet wire from Amazon, hooked it up to an oscilloscope, and dropped a rather large magnet through it. I saw 3-5V spikes and decided it was enough to light a white LED.

What you’ll need:

The spool I bought from Amazon did not have both ends visible. I needed to unwind the spool, pull out the end taped to the core of the spool, and re-wind it. I did this on a lathe, but anything that spins would work (e.g. a drill). You could also re-wind it by hand, but that might take some time.

Here is the circuit:

LED_circuit

Solder up the components on the perf board as per the schematic. After that, drop the magnet through the spool!

Dropping a magnet through a spool of wire to light an LED

2 Responses

    1. Sorry I didn’t see this until now! Gmail started marking my WordPress notifications as spam for some reason.

      It should work if you just reduce the value of the resistor (the white LED I’m using has a forward voltage of about 3.3 V). I connected the output of the coils to an oscilloscope and saw 5+ V. To get higher voltages, you’ll want a bigger magnet or more coils of wire.

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