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.
This circuit was found in documentation from the 1980s. The transistor depends on the desired...
This circuit was found in the magazine Sperimentare 4 of 1977 and can be easily assembled using TIC...
This simple circuit was found in Popular Electronics from the 1980s. The circuit uses an LED as an...