Hi all,
I would like to make a wireless charging device which is based on the reference circuit found in the Internet. Also, these circuits were reverse engineered from a toothbrush. I have built the circuits and there were some problems occurred.
1). MPSA44 will be extremely hot, say, over 120 celcius!, if the coil on the battery(schematic1_battery.pdf in news://news.wonderfuland.net/ snipped-for-privacy@news.hk.gin.net) side is removed. 2). MPSA44 will be hot, around 65 celcius, in normal charging operation. 3). Although the circuits can charge the battery, the waveform across the coil on the battery is not a pure sine wave. Please have a look on the picture in news://news.wonderfuland.net/ snipped-for-privacy@news.hk.gin.net. 4) There are 3 different frequencies existed and they are 100Hz, 57.8kHz and 68kHz.I just know that there are some kinds of LRC ocilliation in high frequency about 50kHz. However I dont know why there are 3 different frequencies waveform in the circuit.
I would like to know what is going wrong in the circuit and how can I improve it? Which components in the circuit can I tune or changed?
Thanks all. I know it is little bit long....
Best, Michael