Capacitive Touch Sensor based morse key

This is another quick and dirty project of mine. I made it in two evenings.
Iam trying to learn CW and Iam not good with mechanical stuff, and buying a finished morse key can be very expensive so another solution had to be found.I read about capacitive touch sensors.

What happens is basically, as you touch the sensor paddles, you increase the capacity of the padle. The microcontroller can measure detect that change. The internal pullup resistors are used to "charge" the sensor paddle. Its not really a measurement because its only a "if bigger than" comparison, where the threshold is set to a fixed level based on the final hardware build.

The sourcecode and schematics on the bottom include another switch for adjusting the speed. That switch is not shown on the pictures and video. If you push & hold the key while touching one of the sensors, the speed will decrease continously and then start from max speed...

Inside 1
Inside 2




- Electrical Junction box (Housing)

- PCB (I made the paddles from that)

- 4 sockets for connecting to power and the TX

- Capacitor

- 4007 Diode (SMD) for Protection

- 7805 SMD Regulator

- Attiny45

- 3 BC847 Transistors

- Some 0805 100nF's and resistors


- Speaker

- Breadboard PCB


PicturesTop ViewSide ViewSchematics
Project filesSchematics FileBascom Souces
VideoVideo File