This circuit identifies the polarity of DC signals and if the signal is AC. The circuit is from 1969 US EDN documentation. Operational may be equivalent.
The drive levels of this shield are opposite to the previous one. The photo-transistor can be of...
This circuit was found in a Radio Electronics of July 1984. It consists of the traditional 1 A...
This flasher or neon signal powered by batteries was found in old documentation. The transformer must...