Metronome

So, you have built an electric cigar box guitar and started to get playing, only to realize that you don't know how. In fact, you can't even keep time. Your playing keeps getting faster and slower. It sounds like you need a metronome. A metronome is a device that helps you keep a steady time when you are playing an instrument by making a tick at a regular interval that you pre-set. If you have a little bit of electronics knowledge, it is very simple to build an electronic metronome.

- TLC555/TLC555CP LinCMOS Timer (8-Pin DIP) (Model: TLC555/TLC555CP | Catalog #: 276-1718)
- (x2) 10µF 35V 20% Radial-lead Electrolytic Capacitor (Model: 272-1025 | Catalog #: 272-1025)
- 10K-Ohm Horizontal-Style Trimmer (Model: 271-282 | Catalog #: 271-282)
- 1K Ohm 1/4-Watt Carbon Film Resistor (Model: 271-1321 | Catalog #: 271-1321)
- (x2) Red LED with Holder (Model: 276-084 | Catalog #: 276-084)
- 8-Ohm Mini Speaker (Model: 273-092 | Catalog #: 273-092)
- 500K Ohm Volume Control with Push Switch (Model: 271-002 | Catalog #: 271-002)
- Hexagonal Control Knob (Model: 274-407 | Catalog #: 274-407)
- Multipurpose PC Board with 417 Holes (Model: 276-150 | Catalog #: 276-150)
- Project Enclosure (5x2.5x2") (Model: 270-1803 | Catalog #: 270-1803)
- Fully Insulated 9V Battery Snap Connectors (Model: 270-325 | Catalog #: 270-325)
- Enercell® Alkaline 9 Volt Battery (Model: 23-853 | Catalog #: 23-853)

Build the circuit according to the schematic, with the exception of the LEDs, the speaker, 9V battery connector, and the potentiometer. Those will be wired in later.

Wire a black wire to the center pin on the side of the potentiometer and a red wire to the right pin.

Wire a red wire to the center pin on the bottom of the potentiometer. Wire another red wire to either of the side pins.

Flip the case on it's side and measure 3/4" in from each side. Center both of these holes along the other axis. Drill them both with a 3/4" drill bit.

Install your LEDs into the case and fasten them in place.

Flip your case up on its small side and make a perfectly centered mark. Drill a 3/8" hole using the mark as a guide.

Install the potentiometer into the 3/8" hole in the side of the case.

On the side of the case with the LEDs, make a mark that is dead centered. Make two 1/4" spaced marks to each side of this center mark to make a plus. Make two more similar marks at each 45 degree diagonal to form a star pattern.

Drill through all of these marks with a 1/8" drill bit.

Wire the LEDs and the speaker to the board as shown in the schematic.

Wire the side connections of the potentiometer to the board as the potentiometer shown in the schematic.

Wire the red wire of the 9V battery connector to one of the red wire on the bottom of the potentiometer. Wire the other red wire from the potentiometer to power on the circuit board.

Finally, wire the black wire of the 9v battery connector to the ground plane on the circuit board.

Hot glue the speaker to the inside of the case in front of the star pattern. The speaker should be able to cover all of the holes when you look at it from the outside.

Plug in the 9V battery to power up the circuit. It might now turn on. If it doesn't turn on, press down on the potentiometer knob to engage the power.

Turn it off.

Fasten the case closed with screws.

Attach the knob to the potentiometer shaft to finish it off.