This crystal configuration can be made with triggers of any logic. The frequency is given by the formula next to the diagram. This setting is specifically for TTL.
This circuit was found in a 1970 IEEE publication. The circuit functions as a voltage controlled...
Found in a documentation from the 90s, this circuit limits and amplifies a voice signal in the 800...
This gas sensor circuit was found in July 1976 Radio Electronics magazine. The TGS sensor was a...