Touch Key

The touch key consists of two metal plates mounted on an insulating base.  The palm of your hand rests on one plate and you send by touching the other plate with fingers.  The resistance of your hand completes the circuit between the plates to actuate the electronics.

In the schematic below, the 56 M resistor pulls the input of one of the inverters of the 4069 high causing its output to go low, biasing the 2N2222 off through the 2.2 K resistor.  When your hand completes the circuit between the two plates, the input of the inverter is pulled low.  The output of the inverter goes high, turning the 2N2222 on to key the transmitter.

 
 
 
 
 
 
 
 

The circuit board layout is for "Manhattan Style" construction.

If you use a wooden base, make sure that you place a non porous material between the touch plate and the wooden base.  The circuit is very sensitive and the resistance of the wood is enough to actuate the key.