This keypad telephone encoder circuit was found in ancient American documentation. The components used are common and are not difficult to obtain.
This circuit can provide a voltage of up to 900 V depending on the input voltage. The diodes must...
This amplifier is from Motorola documentation from the 70s. The circuit uses transistors from the...
This circuit was found in a 1991’s PE Hobbyst Handbook. The circuit is based on altering the sound...