I found a circuit in an old book of 555 timer projects for a non-latching
mains hum single plate touch switch, but I just can't get it to work!

The touch plate is connected to pin 2 of the 555 via a 0.1uF capacitor.

Pin 2 is also connected to the cathode of an IN4001 diode, and the anode of
that diode is connected to 0v

Pin 2 is also connected to the anode of a second IN4001 diode, and cathode
of that diode connects to Vcc. A resistor which supposedly sets the
sensitivity of the circuit is connected in parallel with this diode between
pin 2 of the 555 and Vcc - suggested values "in the range 47K-10M"

According to the book, the 555 should trigger permanently when the resistor
value gets as high as 10M. It doesn't, nor at 20M, nor 30M. This suggest to
me there is a flaw in the design.

I can get it to work with some stability (but not enough!) by simply
connecting pin 2 to the touch plate via a longish wire. I suspect this is
because the wire is picking up background noise sufficient to stop the 555
triggering, and my finger is then dragging the signal down a bit, and the
555 then triggers.

I can also get it to work by going for a leakage based (i.e. two contact
pad) solution of connecting pin 2 to Vcc via a 10M resistor and one pad to
pin 2 and a second to 0v - but it's not that sensitive + I really could do
with a one-pad solution.

Other info about the circuit:

Supply is a 9v battery. There is no indication the circuit needs to be
grounded.
Pin 6/7 are connected to 0V via a 1uF capacitor, and to Vcc via an 820K.
Pin 5 connects to 0v via a 01.uF capacitor.
I'm operating it in the house where there should be plenty of mains hum to
drive the circuit
Pin 3 drives a 9V relay via another IN2001 diode (another IN4001 diode + 1uF
capacitor sit across the coil of the relay)

So if anyone has:

1. Any ideas for getting this circuit to work properly and reliably
OR
2. A really good proven one pad non-latching circuit design which can
preferably run from battery and doesn't need to be grounded
OR
3. Any other proven one-pad non-latching design. I won't rule out a solution
that needs to be grounded and/or mains powered., but its just not as
convenient.

TIA.

Midge.