This circuit uses a diode as a radiation sensor. The operational ones are old because the publication is from the 80's, but modern low voltage equivalents can be tested.
This old configuration of an audio amplifier has a push-pull two-transistor output stage. Output...
This is the traditional configuration of na Astable Multivibrator using two NPN ttransistor....
This circuit is from 1987 documentation. The operating system used is not common today, but two...