This is the basic configuration of an operational amplifier sample & hold circuit. The FET and transistor are commonly used. The circuit is from an 80's documentation.
This circuit uses a unijunction transistor in a different configuration to generate rectangular pulses at...
This basic circuit is from 1984 documentation. This circuit can be used as an efficient burglar alarm...
This circuit was obtained from an American 1980s documentation. The frequency depends on the...