Price - Stock No 57

This 'professional' version of the skill toy eliminates the need for close scrutiny by the game judge.  An instantaneous touch of the game wire to the teardrop terminal will light the LED and sound the buzzer for about 1 second. 


  1. Turn  the PCBoard over so that you are looking at the PLAIN side.
  2. Identify the resistors -  see Resistors and/or use a multimeter.  Bend  the legs of the resistors to a shape that will fit into their locations.  Push them through and firm the resistor down against the PCB. 
  3. These two components may be soldered in place. Refer Soldering Technique . 
  4. LED's are "Light Emitting Diodes".  The LED is polarised  -  a semiconductor - and will not work if placed the wrong way round.  
  5. The LED can be soldered in place.
  6. The 10uF capacitor is polarised and must be inserted with the correct orientation.  The body of the capacitor is marked to assist.  Insert and solder in place.
  7. The 2N7000 must also be inserted with the correct orientation.  Insert and solder.
  8. Push the PCB pins into the correct holes and solder.
  9. Attech the teardrop terminal to its PCB pin with solder.
  10. Push the ends of the battery snap wires through, and solder.  Observe polarity.
  11. Connect the positive and negative wires of the buzzer with solder. 
  12. Bare the ends of the hook-up wire, tin both ends - refer Tinning wire.  Solder one end to one PCB pin. 
  13. Solder the teardrop terminal to the other PCB pin.
  14. If  you  are  fitting a BUZZER, make sure you observe the correct polarity.  Solder the RED (+), and BLACK (-) 
  15. Connect a 9 volt battery and test by touching the end of the wire to the teardrop terminal.

Technology Notes

This circuit uses a 2N7000 FET (Field Effect Tansistor) which, in this application can be simplified to a NPN transistor see  Transistors .  In essence when the Gate  goes high current is allowed to flow in the Drain to Source direction.  This makes the LED and buzzer activate.

The 2N7000 is activated when the probes are touched.  When this occurs, the capacitor fills with charge.  When the probes are disconnected, the charge in the capacitor is released in a controlled fashion by the 22K resistor (about 1 second).  The slowly reducing voltage across the capacitor is fed to the Gate of the 2N7000 which keeps the LED and buzzer activated for about one second. 


If it doesn't work check:


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