This solar powered circuit was found in a 1991 documentation. The transistor is a general purpose NPN.
With the circuit in the figure, it is possible to control the amount of heat generated by the...
We found this circuit in an old European documentation. Transistor TR1 can be BC548 and TR2 can be...
This small telephone transmitter uses a telephone capsule as a microphone. The L1 coil has 4 to 5...