Touch activated LED valentine, circuit.
Basic touch circuit schematic
A touch sensitive pad triggers the beating heart. The PIC is usually in sleep mode, but a signal from the touch switch circuit will wake it. The switch is based on a simple PNP transistor design that uses almost no power when idol. The "switch" part of the transistor is brought out to a pad on the PCB. A tiny charge travels over the skin and into the surrounding ground plain when the pad is touched. The transistor amplifies this and puts a bunch of current on the PIC pin, waking it from sleep mode. One resistor (R1) on the touch pad protects the transistor (Q1) from accidental short-circuits. Another resistor (R2) shunts any transistor leakage to ground, preventing false triggers.