This circuit is from an American publication of the 80's. It makes use of components of the time. However, the circuit is the basis for a modern shield application since the input is TTL.
This circuit uses half of the LM158 operational double but can be used in the series as the LM258,...
This circuit generates audio tones in a speaker with controlled frequency and volume. The...
This circuit was obtained from an article in Radio Electronics magazine in October 1966. It...