The circuit can also be used in games and toys, and the power supply can range from 5 to 12 V. Rx depends on the power-supply voltage and is given in a table in the schematic diagram.
Sensitivity is determined by R1, which can be reduced to values down to 1 M ohm, and the flash rate is determined by R2 in a range from 0.1 to 5 Hz. Transistorized output stages can be added to drive lamps or other powerful loads.
A schematic diagram of the Touch-Triggered LED-Flasher is shown in Fig. 1.
The sensor is formed by two plates or screws placed together, to be touched at same time with your fingers. Positions of the polarized components, such as the LEDs and C2, must be observed.
IC1 - 4093 CMOS integrated circuit
LED -Common red, yellow, or green LED
X1 - Sensor (see text)
R1 -10,000,000 ohm, 1/4 W, 5% resistor
R2 - 2,200,000 ohm, 1/4 W, 5% resistor
R3 - 100,000 ohm, 1/4 W, 5% resistor
Rx - 1/4 W, 5% resistor, value according the power-supply voltage (see text)
C1 - 0.22 µF or 0.47 µF ceramic or metal film capacitor
C2 - 100 µF, 16 WVDC electrolytic capacitor
