This simple injector and signal follower employs a high impedance headset. Transistors can be of general use. The circuit is from old American documentation.
This OF-1 LO oscillator was found in a 1980s American documentation. The transistor can be any...
Found in a Popular Electronics from the 90s, this amplifier uses an operational amplifier of the time....
Short pulses can be found in this 90's EDN circuit. The load is 50 ohms and the transistors are from that...