2. Bend and trim the leads of a 1M resistor as shown in the first experiment. Fit R1 between Y6 and I7 (letter I + 7).
3. Fit bare wire link from I3 to H7.
4. Fit a BS270 MOSFET with its gate in J7, source in Y9 and drain in J8.
Testing the circuit.....
Switch on the 5 volt supply to the programmer module. Press push button S1 and the LED will glow.
With the MOSFET the output current is switched on by raising the input voltage, the actual current which flows into the gate is so low that for all practical uses it can be treated as being zero. To illustrate this pull out the 1M resistor (R1) then press the push button switch. The LED will stay on when the button is released. There is a tiny amount of capacitance at the MOSFET input which gets charged up to 5 volts and the current is so low that it can take between an hour and several days to discharge this capacitance. Replace the 1M resistor (Y6 to I7) and the LED will immediately go out, and only light when the button is pressed.