Touch Switch

  
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. 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.
Touch Switch - schematic

R1 22Meg resistor R2 47K resistor R3,R4 100K resistor R5,R6,R7 2K2 resistor C1 Capacitor, 22?F, 25V C2 Capacitor, 22?F, 25V Q1 MPF102 Q2,Q3 2N3565 Q4 TIP31 La1 Bulb, #53



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