delara news Delaware Amateur Radio Association, Delaware OH   VOL 36 NUMBER 3

Craig

Craig MIller  W8CR

Teen Tech Tesla Coil Follow-up

The other month, I described a project for the local library system to educate teenagers about the wonder of radio and electronics.  As part of the presentation, that was a total success, was to offer simple micro Tesla Coil kits for the kids to build.  Out of 60 kits, 52 kits were successfully assembled, mostly by the children themselves. Before:   After:   Even though several of the sessions were rushed (20 kids in one of the sessions) through the help of volunteers from our local ham club, every child walked out with a working Tesla Coil that sparked and generated RF energy at approximately 2.3 MHz.  They were amazed to see a common fluorescent bulb light up when in the proximity of the coil.  Also they were fascinated that one coil, once energized, actually transmitted power to a nearby coil (lighting of the LED).  This is exactly what Nicola Tesla set out to do back during the turn of the previous century – he wanted to transmit power, wirelessly, to every home in the world.  These little kits may have proved he was on the right track!   A lot of hours committed to this project has paid dividends.  Maybe this experience will encourage some youngster to pursue electrical sciences in their studies. Several kids did ask if these coils could play music.  “Unfortunately no.” was my reply but I promised to look into a design to do just that.  What these teenagers were talking about, they’ve seen videos on Youtube and other social media platforms where engineers were able to modulate the noisy spark emitting from the coil.  If you use two coils, they actually play stereo! Here is a link to a video where two coils play “House of the Rising Sun”: Well, after some careful study of the Tesla Coil circuit, I determined that with the addition of a few simple components and a connection to an audio device like a home stereo may work.  These coils aren’t very big, and I suspect even under the best conditions, the audio output of the coils may be insufficient to fill a room with fantastic music. So I opted to create, possibly for the first time ever, a pair of Tesla Coil headphones:   Using a copper strap as the support of the coil serves a dual purpose: 1- a good mounting method to position the coils at the proper location near the ears, and 2 – provide a suitable counterpoise for the RF energy to “push” off of.  We learned during our Teen Tech sessions that the coils perform much better with a good “ground” underneath them. Once all was rewired, I pulled out one of my favorite albums, ACDC’s “Highway to Hell”.  I cranked that LP up many times back in my old dorm days. The record is queued up, amplifier at an acceptable volume, headphones plugged in - so here we go: (scroll down!)  
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