How tp modify this capacitive sensing circuit

[boylesg]

Given that I simply want to power a LED and I have therefore left out the relay and diodes, how would I modify this circuit to operate at 5-6V and with a small square of Al tape behind a piece of laminated paper?

The circuit does not really conform to an amplifier circuit that I can readily recognize and therefore know how to re-calculate the resistor values.

**broken link removed**
I probably should mention that it is designed for a touch activated feature in a shop window. So I don't really know whether or not the laminating plastic has any dielectric properties. I know the overhead projector sheets do.

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Well I can measure about 1.3mV across the diode when I put my finger on the sensor, so the circuit appears to be working with 6V in, but not enough to turn on the LED.
When I take my finger of the sensor it drops to about 0.9mV within a second or two.

 

[BradtheRad]

In order for Q1's bias wire to pick up the slightest signal, R1 must be very high ohms.

R2 and R3 should be a potentiometer which you will adjust to a point where the led just starts to light.

This is not too different from the simple static charge detector (electroscope), using a JFET.

http://amasci.com/emotor/chargdet.html

Come to think of it, you probably will get better performance if you use a JFET or mosfet. Those are voltage controlled. Your schematic uses transistors which are current controlled, yet your input has hardly any current at all.