Price - Stock No 131



1. Check your P.C.Board carefully for damage to the tracks. A Circuit Tester or a multimeter will help check that there are no broken tracks.

2. Identify the resistors by their colour bands or with a multimeter. Bend the legs with long-nose pliers to match their holes and push them into place against the surface of the board. Remember that the drawing is looking at the PLAIN side with the tracks away from you. When in place, bend the legs sideways a bit to stop the resistors from falling out.   Solder in place - see Soldering Technique

3. Two PCB pins are located at the switch connection points.  Solder in place.

4 . The BC 548  has a flat on the body.  Mount it with the flat as the drawings show.  Care should be taken when soldering the transistors - excessive use of heat from the soldering iron may permanantly damage these components. 

5. Identify the flashing LED and the super bright LED's.  They are polarised. There is a flat at the base of the globe. This is above the K leg, which is also the shorter leg. Put the flats as the drawing shows.  Solder in place.

7 . The switch can now be soldered in place to the PCB pins in step 3..

8. The battery holder is fitted from the track side of the PCB and soldered in place.  Care needs to be taken to ensure excess solder does not short any of the PCB tracks. 

Technology Notes

When the switch is turned on, two super bright LED's illuminate via 390R resistors.  Power is also applied to the flashing LED on through the 470R resistor to 0V.  The junction of the flashing LED and 470R is tapped through a 2K2 resistor and switches the BC 548. 

When the Flashing LED flashes 'on', the junction of the flashing LED and the 470R resistor increases it's voltage, this voltage flows to the 2K2 resistor then through the BC548 (base) to 0V.  The transistor turns on and allows the three super bright LED's to illuminate. 

When the flashing LED flashes 'off' the voltage that was feeding the base of the transistor is removed and the three super bright LED's extinguish. 

The three superbright LED's flash in sync with the flashing LED.  See - Transistors

Have fun and go safely.

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