Price - Stock No 310 

Listen to audio for the Three Melody Generator 

Melody 1 - Santa Clause is coming to town
Melody 2 - We wish you a merry Christmas
Melody 3 - Jingle Bells



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. Bend the legs of the resistor with long-nose pliers to match its holes and push it 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. Insert the IC socket.  Be careful to ensure all legs protrude through the holoes in the PCB.  Solder all legs of the socket.

4. Six PCB pins are located at the locations shown.  Solder in place.

5. The 0.1uF capacitor can be inserted and soldered

6. Identify the LED legs.  It is polarised. There is a flat at the base of the globe. This is above the K leg, which is also the shorter leg. Insert the LED as the drawing shows.  Solder in place.

7. The battery holder is connected to the PCB pins as shown.  Solder to the PCB pins. 

8 Cut the fig. 8  wire into two appropriate lengths, one for the speaker, one for the switch.  Strip the insulation approx 5 mm from each end.  Tin the ends of the wire - See Tinning wire .

9.  The Speaker has +ve and -ve terminals, use one length of fig 8 wire to connect the terminals to their respective PCB pins.

10.  Use the second length of fig 8 wire to connect the switch to the chosen trigger.

11.  You will find that the legs of the HK227 are spread a little wide to fit into their sockets.  Take each IC and rest  the  legs  on  a flat  surface.   Gently  push  down  so that row of legs is straightened a little.  Repeat for the other row of legs.  Take the IC and find the locating mark on the top surface and near or at one end.  Check the drawing and push it into its socket the right way round. 

11. Insert batteries and press the switch to test.

Trouble shooting

Troubleshooting  if necessary will involve careful checking of locations and polarity of components. 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.

Technology Notes

The heart of this kit is the HK221 which is a purpose built Integrated Circuit for melody generation.  The output of this IC is fed directly to the speaker.

View the HK227 Datasheet

Contact CdS electronics

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