Beginning Circuitry: Build a Metronome

Estimated Completion Time: 5 hours
Difficulty Level: Beginner

Metrnome kit

Are you a practicing musician? Do you love playing your instrument and improving your skill? Well, every musician needs to practice, but how can practice be complete without your very own homemade metronome? This beginner circuit can be a great way to spark your interest in electronics and circuitry. The metronome is powered by a simple 9 Volt battery and utilizes one of the most common timing integrated circuits, the 555 IC. Being both practical and educational, this project is a great way to spend a few hours of the weekend.

	Resistor
	Polarized Capacitor
	LED
	555IC
	Potentiometer
	Ground
	Speaker

Schematic:

Step 1: Examine your perforated board (P/N 263215) to route components to each other.

Step 2: Solder leads.

Begin with your IP socket (P/N 112206) Pick a spot for it close to the top of the board and solder only a couple of its leads at first. Until you are completely comfortable with its placement, solder the rest of its leads.

Step 3: Adding components

Often times, it's easier to begin with the lowest sitting components. A lower profile leaves the board easier to navigate around, so we will begin with the lowest lying components: the resistors (P/N 661503)

Step 4: Capacitors

Capacitors are next (P/N 1946295). If you can spare the real estate, bend their leads to a right angle so they can also lie on the board.

Step 5: Wire the board

Now that the components are set go ahead and wire the board (P/N 263215) Use solid core wire (P/N 36768), since it is easier to work with. Don't forget to use strips as short as you can make them. For the speaker, potentiometer, and LEDs cut some wire about 3-4 inches long and solder the wire to the board. The end of the wire will be soldered to the parts to give more length to them.

Step 6: Attach components

Attach your potentiometer (P/N 241681), speaker (P/N 320362), LEDs (P/N 34761), battery clip (P/N 11280), and switch (P/N 317228) to the board via extended wires. Although the switch isn't shown on the schematic, it can be easily incorporated into the project. Attach one of the two PINs of the switch to the positive lead (red) of the battery clip. The other pin is connected to the board using wire. The switch should act as an extension to the clip. Insert the timer IC (P/N 27422) in the correct direction.

Step 7: Prepare enclosure

Now it's time for the enclosure. Begin by covering the lid of the box with masking tape, preferably white. With a pencil, ruler and a t-square, carefully mark your holes. I would suggest drawing a grid and using the intersections as points to drill. Center and trace the speaker.

With a pen, mark the spots for the rest of the parts and make sure to leave enough room for the battery (P/N 2112461). I chose to stand it up at the rear of the box. Make sure your bits are the appropriate size and begin to drill.

After you have drilled the holes for the front of the enclosure, proceed to drill holes in the back to mount your board. Leave room for the battery. Use separate screws (P/N 2094400), nuts (P/N 40943), and washers (P/N 106826) to mount the board.

The back of your enclosure should look like this, with rubber feet (P/N 126981) still to come.

Step 8: Make music

Your finished product. Use the nuts and washers that came with the parts to secure your knob and switch to the front of the box. Hot glue works great to attach the speaker and LEDs.

Kit includes:

Part No.	Qty.	Description
18893	1	Enclosure, high class ABS plastic speedy box
265009	1	Knob,1/4 shaft, 24mm, black,w/ set screw
317228	1	Switch, toggle, solder lug, panel mount
34761	1	LEDs (2), uni-color green, 565nm, 2-pin, T-1 3/4
2112461	1	Battery, 9V, Super Alkaline
1946295	1	Capacitor, electrolytic, radial, 22μF, 16V, 20%
27422	1	555 IC, Standard Timer, Single, 8-Pin, MDIP Rail
112206	1	IC Socket, 8-Pin, Dual Wipe, Soldertail
661503	1	Resistor (3), 1.0k ohms, 1/2 watt, 5%
126981	1	Rubber Feet (4), SJ-5023 Series, Bumpon
40943	1	Nut (4), Hex, 4-40, Zinc-plated Steel
2094400	1	Screw (4), Pan Head, PPN 4-40 x 1/2, Phillips
106826	1	Washer (12), Flat, #4, 9/32 (OD), Zinc-plated Steel
241681	1	Potentiometer, Resistor, 250k ohms, 10%, 2W, Solder Lug, Panel Mount
36768	1	Wire, 22 AWG, Solid, Blue, 100 ft.
11280	1	Battery Clip, for 9 Volt
320362	1	Speaker, Round, Ferrite, 8 ohms, 5W
263215	1	Proto Board, 2.5 x 4.5, 5640 Holes, Plated Thru

Recommended Solder Starter Kit (P/N 358598)

Recommended Solder (P/N 73576)

Troubleshooting Issues:

LEDs will not light, sound isn't produced, turning the knob doesn't affect the tick-rate, etc.

1. Check the soldering job. Make sure the solder from leads don't touch each other.
2. Replace the battery.
3. Match components with the schematic's specifications.
3. Check for damaged components.
4. Make sure polarized components are oriented correctly on the board (e.g. IC, capacitors, and LEDs).

About the author:

This project was assembled by Ari Dubinsky. Ari is a graduate of Carlmont High School and will be attending Cal Poly San Luis Obispo in the fall of 2010, pursuing a degree in Electrical Engineering. Ari has teamed up with Jameco to accelerate his learning as well as to lend a helping hand to a major electronics distributor. His interests include shredding on the guitar, martial arts, and music production.