Build your own speaker
Materials
Required Materials
|
Part |
Quantity |
Comments |
|
2 ohm resistor |
2 |
|
|
10 ohm resistor |
2 |
|
|
220 ohm resistor |
1 |
|
|
270 ohm resistor |
1 |
|
|
1k ohm resistor |
2 |
|
|
2.7k ohm resistor |
1 |
|
|
3.3k ohm resistor |
1 |
|
|
39k ohm resistor |
1 |
|
|
82k ohm resistor |
1 |
|
|
1µF capacitor |
1 |
|
|
1µF non-polarized capacitor |
2 |
Ceramic capacitors are perfect here |
|
22µF capacitor |
1 |
|
|
470µF capacitor |
1 |
|
|
2n4401 transistor |
3 |
|
|
2n4403 transistor |
1 |
|
|
1n4002 diode |
2 |
|
|
Prototyping board |
1 |
|
|
Speaker box |
1 |
Needs to fit the chosen protoboard and speaker. We used 6 x 4 x 3 inches |
|
Speaker (4 ohm 3 watts) |
1 |
Adafruit has a pretty good one we chose to use |
|
Wire 26 AWG |
|
Solid core is recommended. 2 or more colors may help in identifying positive and negative runs, but not required |
|
Audio cable |
1 |
3.5mm tip-ring-sleeve (TRS) male-male |
|
DC 12v power cable |
1 |
2.1mm barrel connector |
|
DC 12v power jack |
1 |
2.1mm barrel connector |
|
Mounting hardware |
|
We used (4) M2*12 screws and (12) M2 nuts for mounting the board, and (4) M3*8 screws and (4) M3 nuts for mounting the speaker |
|
Soldering Iron |
1 |
|
|
Wire strippers |
1 |
If handled VERY carefully, a sharp knife can be used for stripping the wire insulation |
Optional Materials
|
Part |
Quantity |
Comments |
|
Audio jack |
1 |
No need to cut audio cable, makes cable replaceable, much cleaner look |
|
Multimeter |
1 |
Very helpful for troubleshooting and checking jack pins |
Building the Board
For the purposes of this example, we will be referencing the holes on the prototyping board by a letter and number combination. The letters A-J represent the row the hole is in, starting with A on the bottom. Likewise, the numbers 1-30 represent the column the hole is in, starting with 1 on the left. In each column, A-E are a connected bus, and F-J are connected to a separate bus. This results in 60 total bus connections.
When creating a circuit on a soldered board, there are a few approaches one can take to adding the components. One of those approaches is the smallest-first approach. This means that we will add the smaller components before the larger ones. This is the approach we will be taking.
Wires
Let’s start by installing the wire connections between buses. Here are the series of connections that need to be made.
-
F3-E3
-
F5-E5
-
H5-H8
-
H9-H12
-
F13-E13
-
F15-E15
-
F16-F22
-
E16-E22
-
F26-E26
-
C7-C8
-
J11-POWER
-
J21-POWER
-
A21-GROUND
Resistors
Next, we will add the resistors. Direction does not matter for these.
-
J16-POWER (1k ohm)
-
A16-GROUND (1k ohm)
-
H1-H3 (10 ohm)
-
C1-C3 (10 ohm)
-
G23-G26 (2 ohm)
-
D23-D26 (2 ohm)
-
E7-F7 (220 ohm)
-
J9-POWER (3.3k ohm)
-
A5-GROUND (39k ohm)
-
J5-POWER (82k ohm)
-
A7-GROUND (2.7k ohm)
-
A13-GROUND (270 ohm)
Diodes
Each diode should be marked with a direction. Typically, there is a colored stripe on one side indicating the output of the diode. Pay close attention to the direction of each diode, they are not th e same.
-
G16-G15 (1n4002, output on G15)
-
D15-D16 (1n4002, output on D16)
Capacitors
lElectrolytic capacitors have a positive and negative lead. The negative will be marked with a stripe on the capacitor body and have a shorter leg than the positive. The ceramic non-polarized capacitors do not have this stipulation and can be installed in either direction.
-
I13-I16 (1µF, non-polarized)
-
B13-B16 (1µF, non-polarized)
-
G5-G3 (1µF, negative on G3)
-
A8-GROUND (22µF, negative on GROUND)
-
C26-C29 (470µF, negative on C29)
Transistors
Pay very close attention to the orientation of each transistor. Each one will have a curved side and a flat side. Also, there will be 3 holes listed, which is where each of the legs go. The orientation will be designated by listing whether the flat side faces POWER or GROUND.
-
B21, B22, B23 (2n4403, flat side facing POWER)
-
I21, I22, I23 (2n4401, flat side facing POWER)
-
G11, G12, G13 (2n4401, flat side facing POWER)
-
G7, G8, G9 (2n4401, flat side facing GROUND)
Preparing the box
Now that the circuit board is mostly finished, let’s turn our attention to the speaker box.
The first step is cutting out a hole for the speaker. The hole will need to be about 2¾” in diameter. We put ours on the box “lid” to make displaying the circuit easier. Then, punch the holes for the mounting hardware. Solder wires to the positive and negative terminal of the speaker. It is recommended to use different color wires, and you can optionally twist the wires together for cable management purposes. Install the speaker using the M3 screws and nuts.
Next, we will prepare the audio cable. If you chose to install an audio jack, cut the hole for that. Using either the data sheet for your jack, or using a multimeter, find the “sleeve” or ground soldering lug and take note of that. Solder wires to the three terminals. It is recommended to use two different color wires. The “sleeve” or ground wire should be a unique color for easy identification. Install the jack into the box, with the wires going inside.
If you chose to solder the audio cable directly to the board, cut the plug off of one end of the cable. Cut a hole in the box and feed the cut end of the cable through it.
Lastly, it’s time to work on the power cable. Cut the hole for the power jack. Determine the negative soldering lug for your jack. Pay close attention to the power supply you purchased. Some are “center-negative” and some are “center-positive”. There will be a symbol on the power brick showing you what you have. You can find the symbol explanations here. Draw the proper symbol near your power jack for future reference.
Some power jacks also include a third terminal, which is used for disconnecting an optional battery. Make sure you don’t use this lug, as it will “disconnect” when the power plug is connected. Solder two wires to the proper lug. Again, it is highly recommended to use two different color wires. Install the jack into the box, with the wires going inside.
Connecting it all together
We are finally ready to start putting everything together and firing this thing up! Let’s start with mounting the board inside of the box. Find where you want to mount the board and mark the hole locations. Punch holes at these spots, and install M3 screws with the head on the outside. Install (2) M3 nuts on each screw, attaching it to the box and creating a small standoff. Test fit your board.
With the board removed, attach the wire for the AUDIO input, the 12v power, and SPEAKER output at the locations specified.
-
F1 (AUDIO L or R)
-
E1 (AUDIO L or R)
-
GROUND (AUDIO negative)
-
A29 (SPEAKER positive)
-
GROUND (SPEAKER negative)
-
POWER (12v positive)
-
GROUND (12v negative)
Install your board to the previously created mounting points. Make sure you use your last M3 nuts to attach it securely to the screws. It’s now time to test your board! We recommend plugging your headphone cable in before powering on. Once the power is plugged in, audio will begin playing from the headphone jack. If you do not have anything plugged in, it may sound like a buzz.
Troubleshooting
There is smoke when powered on
DISCONNECT POWER IMMEDIATELY! Part of the circuit has likely been fried. Remove the board and inspect for any burnt components. These will need to be replaced. Verify you wired your power jack correctly. Reference your power cable to determine whether you have
center-positive or center-negative, and verify your jack is wired appropriately.
Nothing happens when powered on
Using a multimeter, while plugged in, verify the voltage between your positive and negative power rails. It should read at least 12 volts. If there is no power, check the voltage between the soldering lugs of your power jack. If it still reads as zero, and there is a third lug, measure the voltage between that lug and ground. If you still get no power, you either have a bad power cable or there is a problem with the outlet itself.
