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 is from a 90s Popular Electronics. The circuit employs a ZN461E that is not a common...
This full-wave precision circuit was obtained from a 90's Radio Electronics. The circuit must be...
This traditional doubler configuration with the 555 can be found in other articles on the author’s site....