Found in a Popular Electronics from the 1990s, this circuit is a 1-digit counter that advances under the command of S2. The circuit can be expanded to more digits.
We found this circuit in an old documentation from the 70s. The sensor is an LDR that must be...
This circuit with junction field effect transistors was found in documentation from the 1980s. The...
Common general purpose silicon diodes when direct biased provide a voltage fall of about 0.6 to...