RSSVol. 17: Random Music Box
Microprocessor organ and servo drum play an endless song.
By Kevin Weekly
Photos by Sam Murphy
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+ Downloads & Extras:
| Part. No. | Value | Estimated Price |
| C1 | 10uF | $0.07 |
| C2 | 1uF | $0.07 |
| C3 | 20nF (203) | $0.02 |
| C4 | 100uF | $0.08 |
| J1 | .1" headers | $0.10 |
| R1 | 50K smd pot | $0.50 |
| R2 | 50K smd pot | $0.50 |
| R3 | 50K smd pot | $0.50 |
| R4 | 10K | $0.01 |
| R5 | 10K | $0.01 |
| R6 | 10K | $0.01 |
| R7 | 4.7K | $0.01 |
| R8 | 10K | $0.01 |
| R9 | 10K | $0.01 |
| R10 | 10K | $0.01 |
| SP | 8ohm spkr | $2.49 (radio shack) |
| U1 | OPA4342 | $2.27 (digikey) |
| U2 | PIC16F685 | $2.58 (digikey) |
| DIP Socket | 14-pin | $1.29 |
| DIP Socket | 20-pin | $0.69 |
| Servo (optional) | HS-422 | $15 (hobby shop) |
| Protoboard or Breadboard | $5 | |
| Cardboard | look around | |
| Total | $32 |
Some notes about the materials:
C1, C2, and C4 are minimum (you can replace them with higher valued caps)
The requirement for the potentiometers R1, R2, R3 is that they are the same value. They can even be replaced by equal-valued resistors.
U1 can be replaced by any equivalent op amp, such as the cheaper LM324
The servo can probably be different, but I cannot guarantee another servo will recognize the PWM commands. I tried the HS-325HB servo and it did nothing but twitch.
+ LINKS
Random Music Box on Make: Projects
Schematic Diagram, SCH File for Layout Editor (SCH)
Schematic Diagram and Materials Table (JPG)
GIMP File of Wiring (XCF)
Compiled Firmware (HEX)
Project Source Code (ASM)
Audio Sample 2 (MP3)
Audio Sample 1 (MP3)
Circuit Assembly Steps: Socket Placement (PNG)
Circuit Assembly Steps: Resistor Placement (PNG)
Circuit Assembly Steps: Capacitor Placement (PNG)
Circuit Assembly Steps: Power Wire Placement (PNG)
Circuit Assembly Steps: Signal Wire Placement (PNG)
Circuit Assembly Steps: Potentiometer Connections (PNG)
Circuit Assembly Steps: Output Connections (PNG)
PIC programmer
Digi-Key for PIC16F685 microprocessor, 20-pin DIP
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