Morse Code with touch button (555)

Posted on Sep 9, 2012

This simple CPO is for those who want to practice Morse Code in a different way, ie with out the morse key. It can be also used as a touch operated door bell. The popular timer IC555 is wired as astable multivibrator. 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.

Morse Code with touch button (555)
Click here to download the full size of the above Circuit.

Many touch switches restrict the size of the touch switch. In this circuit the length of wire between the base of the transistor and the touch plate is not critical. In prototype i used 9 cm wire and 3 x 6 cm 3mm thick aluminium plate for touch plate.

Leave Comment

characters left:

New Circuits



Popular Circuits

Variable (Adjustable) Current Limiter Circuit
50MHz frequency counter V-meter & SWR/PWR indicator
big e stereo parabolic microphone
airbag diagnostic code 51 ford f150
Small Footprint Square Wave Oscillator
SEISMIC RADIO 500mHz - 200Hz frequency range
One Foot Spot Welder circuit uses IC CD4541
Brushless motor rotor a stator and a drive circuit