Note: The lamp shown is not supplied unless requested. A festoon bulb is supplied.
Note: Aligator clips may replace the auto plug.
Note: Aligator clips may replace the auto plug.
Schematic Diagram
PCB LayoutConstruction
2. A Circuit Board Holder is useful in freeing both hands for mounting and soldering the components. A spring board clip can be screwed down and will hold the board securely. Wooden blocks with a suitable groove, and able to slide (say on two pieces of dowel) to adjust to the varying lengths of PC Board also work well. Commercially produced stands are available, with an alternative magnifying glass. (types and prices available).
3. Mounting the components is relatively easy. The resistors will have to have the legs bent to match their holes. They may either be mounted to stand vertically or flush on the PCB, except, please note that R5 must be mounted flat on the board to clear under the body of the power transistor.
4. The power diode has a band at the neg (K) end. Polarity must be observed. (This diode is there to protect the unit from the effects of connecting it to the battery in the wrong polarity). The Electrolytic Capacitor also is polarised. There is an arrow on the body pointing down the negative (K) leg. You will notice that the Trimpot has one outside and centre legs joined in the track. This is correct; the other outside leg goes to the other track as indicated.
5. The small Transistor (BC558) has a flat on the body. The transistor is mounted with the flat towards the large transistor. The Power Transistor (2N3055) will fit the holes perfectly, so it is unlikely you will mount it the wrong way round. Note that one hole in the track is drilled D3mm to match the hole in the metal body. The metal body is the Collector (C) of this transistor. Use the 3mm machine screw and two nuts to join it to the track. Feed the screw down through the transistor hole and put a nut top and bottom of the PCBoard. The legs can then be soldered.
6. The six pins can be pushed into their holes. Soldering Technique is most important.
7. If you are fitting a switch to allow the unit to be have a trouble light mode then this switch is connected (by wires) to Pins 2 and 3.
8. Test the unit and adjust the flash rate with the trimpot. N.B.: This unit will work only on FULLY RECTIFIED CURRENT. It will NOT work from a power-pak plugged into a power outlet. A car battery is best but a 9Volt battery will work. If the unit doesn't work, check polarity of all components (diode,capacitor,transistors). Check the colour bands to ensure resistors are in correct places. Check that the trimpot bridges across the tracks with one outside and centre legs. Visually check soldering; resolder any suspect joints. Check for bridges of solder between tracks and remove them. The circuit is reliable and robust. Exercise meticulous care in putting it together and it will fire up first time.
If you are electing to construct the Flashing Beacon via the template/insulator method, the template appears below
