A Simple Touch 'Code' Keyer

An Inexpensive Circuit With An IC And A Few Parts

Imagine tapping the table to generate Morse Code! This simple code practice oscillator is for those who want to practice Morse Code in a different way, without the Morse key. It can be also used as a touch operated door bell.

The popular timer IC555 is wired as astable multi-vibrator. The frequency (tone) can be changed by varying the 100 K variable resistor between pin 7 and 6 of timer IC555. The volume can be changed by varying the 10 K variable resistor and the sensitivity of touch plate can be controlled by adjusting the 1 K Ohms preset at pin 4 of IC555.

The touch plate is connected to the base of transistor BC147B. In this circuit the length of wire between the base of the transistor and the touch plate is not critical. Typical is a 9 cm wire and a 3 x 6 cm 3mm thick aluminum plate. The addition of a relay or additional circuitry could key your transceiver.