Touch Switch with transistors


Touch Switch with transistors

Parts List:

Part Description Radio Shack # DigiKey # Notes
R1 22Meg resistor red red green gold
R2 47K resistor yellow purple orange gold
R3,R4 100K resistor brown black yellow gold
R5,R6,R7 2K2 resistor red red red gold
C1 Capacitor, 22µF, 25V Electrolytic
C2 Capacitor, 22µF, 25V Electrolytic
Q1 MPF102 Transistor, NPN
Q2,Q3 2N3565 Transistor, NPN
Q4 TIP31 Transistor, NPN
La1 Bulb, #53 Try others

Couple Notes:
The MPF102 (Q1) can be replaced with a NTE451 or ECG451, but still widely available. JFET-N-CHAN, UHF/VHF AMP
The 2N3565 (Q1/Q2) can be replace with a 2N2222(A), BC107, BC108, BC109(A/B/C), NTE123A, or ECG123A.
The TIP31 (Q3) can be replaced with a NTE196 or ECG196, but is a common type and widely available. NO suffix.

The ’Touch Plate’ can be anything non corrosive.I use a silver quarter.

You can also use a small relay instead of the #53 bulb.

The phone number for DigiKey is 1-800-Digi-Key.


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