Parts List -
R1 - 1 - 10 Meg 1/4W Resistor
R2 - 1 - 47K 1/4W Resistor
R3 - 1 - 120k 1/4W Resistor
R4 - 1 - 470 Ohm 1/4W Resistor
C1 - 1 - 15uF Electrolytic Capacitor
D1 - 1 - 1N4007 Silicon Rectifier Diode
Q1 - 1 - 2N5458 N Channel Field Effect Transistor
Q2 - 1 - 2N2222 NPN Transistor 2N3904
Q3 - 1 - 2N3906 PNP Transistor
K1 - 1 - Relay w/12V Coil, Contacts To Suit Application
MISC - 1 - Board, Wire, Small Metal Pad For Touch Pad
Notes
1. The touch pad can be most easily made by cutting a small square of PCB material and then soldering on a single wire. Alternatively, something like a penny glued to a plastic backing will do the job.
2. As mentioned, a latching relay can be used so that a momentary touch activates the relay and it remains active. To turn off a latching relay, power must be interrupted. So a 2nd circuit with a normal relay can be used to cut power (use the NC contacts on the 2nd circuit). Placed side by side, two touch pads form an "on" and an "off" pad.
