I just let the smoke out of my testing setup. I designed and built a simple power supply using this guide. I built a capacitive power supply with a bridge rectifier and a final 3.3VDC voltage regulator, and it appears to have not worked. I plugged my power supply into 110 VAC and tested the voltage output at the regulator and got 3.3 VDC as expected, but there was also still a 6.3 VAC component at the output. Now, I'm not a clever man, and I assumed that this AC component wouldn't hurt anything, and boy was I wrong. I blew out my PIC32, a wifi module, and my PICkit3 -- go me.
For the curious, C1 was 4.7 uF, R1 was 4.7 ohm, C2 was 470 uF, and D1 was 6.8 V
What I'm trying to do is build a low cost, physically small power supply to step down mains power to 3.3VDC. Transformers are large and I'd like to stay away from them if possible. Does anyone have any experience with flyback transformer designs -- they seem complex?
Any advise as to what I did wrong and what I can do to fix it? Any other design ideas?