TWO-TONE

DOOR BELL

INSTRUCTION SHEET

 

Price - Stock No 240

Check Your Kit

Schematic Diagram

PCB Layout

  1. To print the Board Refer Printing Boards.
  2. Inspect the tracks for fine breaks and test the continuity of each track with  an  electronic  circuit  tester  or  ohm-meter.  
  3. Bend  the  legs of the resistors to match their respective holes and push them through from the plain side of the P.C.Board.  The resistors are all the same value so they are interchangable.
  4. The three 1N4002 diodes are can be bent to shape and  mounted  with their band to the K end of the space. - see the placement sheet.
  5. The 8 pin  IC  socket can be pushed carefully into place. Soldering is best done progressively as you mount say 4 or 5 components. Refer Soldering Technique
  6. There are three electrolytic capacitors.   Their  values are  marked on the blue body, and there is also an arrow pointing down one  leg.  This leg is the negative leg.  Polarity must be observed.  The .022uF disc ceramic capacitor (C2) can go in any way round.
  7. Two pins can be pushed into the holes where the speaker  connects and  two  more  where  the push-button switch goes.  These can be soldered off.  The speaker is connected by means of the Fig.8 wire.  Bare the  ends and  solder  the plain one to the negative rail of the Board and the other end to the - ve pole of the speaker.  The wire  with  the  trace  is  then soldered to the +ve pole and to the other pin.  The  push-button  switch can be offered into position with its legs against the two pins and pushed right down  to  the  board,  and  standing upright.  Solder  the poles along the pins but remember that the switch is  made of plastic so be careful not to apply too much heat.
  8. The transistor is now placed in accordance with the PCB Layout diagram.
  9. Find the locating DOT on the 555 IC and arrange it as the  drawing shows.   To  fit the 555 it is best to use an IC inserting tool but if one is not available it will probably be necessary to bend the legs inwards  a little by placing one set of legs on a flat surface and push down lightly.  This will maintain their alignment.  Repeat for the other side of the chip so they match the socket.  Push the IC into place.
  10. The  battery  holder  is mounted from the TRACK side.  This will give the correct polarity.   Push the battery  holder  into  place  and  solder. Check your two joints with a continuity tester. When  the battery (9Volt) is placed in the holder you should hear a click from the speaker.  Push the button and release it and you  have  two distinct tones.

TROUBLESHOOTING

Troubleshooting  if necessary will involve careful checking of locations and polarity of components, mainly the electrolytic capacitors, the diodes D1,D2,D3 and that the locating DOT on the 555 IC is as the drawing shows. Re-solder all joints and check to make  sure  you  have  not  bridged across  between  any  two adjacent component legs.  The end  of  a  broken  hacksaw  blade  sharpened  on  an  emery wheel is a good tool for cleaning between soldered joints.

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