Decide on prototype
We thought we’d decided what project to build (I thought we were building Wireless Electricity), but Jamison changed his mind. After further research, he decided to build the Low-Power Wireless Charging he’d found on Instructables.com. I’m pleased. We’ll have more control over this project.
Buy materials for prototype
Once we knew what project to build, we thought it would be easy to buy the parts. Wrong!
Buying capacitors is a confusing process. The units are insane. The instructable specified a 100 nF capacitor. That sounds easy enough. Unfortunately, Fry’s shelf labels would list it as a 100000 pF or a .10 MFD. That’s if they actually had it. After trying to find the right caps, we decided to do our shopping online instead and headed over to digikey.com. We had all the parts we needed the next day. :-)
Prototype building went well, at least for the circuit. Once Jamison understood how the little holes in the breadboard are connected, the oscillator went together fairly quickly.
The first coil went together fast, too. The instructable said to do 18 wraps of 15 cm loops. Jamison wrapped the coil around a form, about 4.5 inches square, and then rounded the coil by hand.
Tuning the coil was a problem. The oscillator was designed for 80 kHz. We should have been able to tune the coil by connecting it to the oscillator and removing coils until the oscilloscope showed something near 80 kHz. Famous last words. Instead of a nice sinusoidal signal, we got a noisy, stepped signal. Removing coils didn’t seem to do anything. Maybe the coils were separating, so we wrapped it in electrical tape. That made no noticeable change. Maybe the cheap power supply was causing the noise. Fry’s could rescue us with a nice benchtop power supply.
Time to call it quits and figure out our next step.
But wait — there’s more
See all posts on Jamison’s Wireless Power Transmission project.