Using a touch sensor – see bottom of page – is very easy.  Just put it into a voltage divider circuit with some high value resistors.  Touching the pad is equivalent to putting a large resistor in parallel so that the output voltage is pulled up towards the battery voltage.  None of the Crocodile Technology circuits work as shown - you will need to put a switch in parallel with the sensor to simulate the action of the block.

This time the touch pad is at the bottom of the voltage divider so that it pulls the voltage down when touched.  The 100k resistor provides some protection for the following block if a direct short circuit is put across the touch pad.  It’s not really necessary in most cases.

With a touch pad both top and bottom you get a double acting switch.  This is not usually a good idea because the output voltage is floating – it’s not clear what value it should have.  But it is used in the next block below – the touch bistable.

A bistable is stable in two states, output either high or low.  The very high input impedance of the FET combined with the capacitor means that this block will stay however you set it for a pretty long time (not sure how long actually, it depends on leakage currents).  Touch the top pad to turn the FET on and touch the bottom pad to turn the FET off.

With a touch pad and a capacitor you can build a timer block.  It needs to feed into a FET driver with a high input resistor, say 10M, from the FET’s gate to zero volts.  The FET will be switched on as long as the voltage across the capacitor is above the gate threshold voltage for the FET.  The capacitor discharges through the gate resistor (10M) providing a fairly long time period.  Exact time period depends on the FET’s threshold voltage and the capacitor’s leakage current.

The block above is slow to charge up due to the relatively high resistance of the touch pad when touched.  A smaller capacitor can charge up more quickly, turning the buffer transistor on allowing the main capacitor to charge up quickly.  This means that even a brief touch will charge the capacitor fully providing the full time delay.

The touch pad used in all the blocks above is simply a piece of PCB with fingers of copper intermeshing.  Make sure the gap between the tracks is clean so that they are not short-circuited.