DIY Synthesizer

Use a blank circuit board to assemble your circuit.

A synthesizer is an electrical musical instrument that generates wave forms of varying frequencies. They range in complexity from basic circuits with one frequency to 88-key digital keyboards with multiple presets and MIDI compatibility. While many synthesizers feature piano-type keyboard interface, you can create your own synthesizer from a basic circuit. This saves money on custom equipment and serves as a convenient introduction to circuit building.

Things You'll Need

• Breadboard (blank circuit board)
• Potentiometers
• Resistors
• Switches
• Ceramic capacitors
• Electrolytic capacitors
• Diodes
• IC chips
• Schematic
• Chassis
• Wire
• Soldering iron
• Solder
• 1/4-inch balanced jacks
• Wire cutters
• 9-volt battery snap

Instructions

1. Code the schematic. This is the document that illustrates the layout and relationship of the board-mounted components. Use a color for each separate component, its turret on the board and its place on the schematic. This way, you easily can cross-reference the schematic and the physical circuit.

2. Populate the breadboard. This is a blank circuit board. On the base, it has a copper trace strip that conducts the voltage from one component to the next. The top has predrilled turrets, into which you slot the board-mounted components. Starting with the resistors, capacitors, switches, diodes, IC chips and finishing with the potentiometers, slot each piece into the relevant turret so the connector pins poke through the base.

3. Turn on the soldering iron.

4. Turn the circuit over, and gently press the connector pins down against the copper trace strip.

5. Put a small amount of solder on the tip of the iron, and press the tip of the iron against the connector pins, fusing it to the copper trace. Repeat this process for all components.

6. Cut a piece of wire for the 1/4-jack. Solder the wire to the output terminal. Solder the other wire to the board eyelet next to the nearest resistor. The resistor governs the flow of current from the board into the output jack.

7. Solder the red wire of the battery snap to the positive eyelet on the board. Solder the black wire to the negative terminal.

8. Fit a 9-volt battery into the battery snap.

9. Fit dials onto the top of the potentiometer pole. A potentiometer is a variable resistor that alters the flow of current relative to the position of slider. The pole governs the position of the potentiometer slider, which governs the amount of current flowing from the potentiometer to the next stage in the circuit. This is how you change the sounds. For example, if you drop the current flowing into an oscillator IC chip, this lowers the prominence of the sound wave created by that chip in the overall output of sound.

10. Screw the board into the base of the chassis with a Phillips screwdriver and standard 4-40 gauge circuit board screws.

Tips & Warnings

• Only solder in a well-ventilated environment.

• Never touch the top of a soldering iron once it is turned on.

References

• Music From Outer Space: Your First Synth
• K P Sec: Soldering Guide, John Hewes, 2010