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 fully passive circuit was found in documentation from the 1970s. The circuit uses an optical...
This circuit of old documentation is based on an operational amplifier that is no longer used...
This circuit was found in a Japanese publication from the 1960s. It uses germanium transistors and is powered...