This circuit was found in a 1980s documentation. Similar configurations appear in the section, but from different sources. The circuit makes use of components of the time.
Found in a 90s 73 magazine, this circuit uses an unusual component today which is the XR2206. |...
This random noise or white noise generator was published in Radio Electronics magazine in July...
This circuit was found in Philips documentation from 1967. The phototransistor is from that time,...