This circuit was found in a 1980s documentation for amateur radio. The circuit makes use of components of the era, but modern equivalents can be used.
This circuit was found in old documentation, however the components used are common today. The...
This circuit is from a 1964 Electronic Design. The sensor is an LDR and the transistors are...
This circuit from Delta Products was published in the May 1974 Radio Electronics magazine. The...