Found in a 1980s American documentation, this circuit operates with 5 V signals requiring 55 cycles of 500 Hz for tone recognition. The circuit can be adapted to operate with other frequencies.
Found in a 1967 American publication, this circuit with feedback for two transistors has a gain of...
This circuit was found in an Elektor from the 90s. Next to the circuit we have a table with the...
In the figure we have the way to implement the E (AND) function with two inputs, in the case of...