Joule Thief: JTBasic with Loopstick and Capacitor: Mode Switching
I took a standard loopstick 1-10 mHy variable inductor and wound a “primary” on top of the loopstick’s original coils. I used this arrangement as the inductor in my JTBasic testbed, with the 2n2222a transistor and a 1K base resistance. I also arranged a 70 nF capacitor that can be switched to be in parallel with the base resistor, or disconnected. There is also a 1 ohm current-viewing resistor at the negative battery connection. I use the DMM on the 200 mV setting to monitor the voltage drop across this resistor, which by Ohm’s law then allows the direct reading of the input current in milliAmps. Some interesting effects are demonstrated. The automatic mode change is very interesting and looks equally so on the oscilloscope (not shown in this video, sorry.)
