a1ronzo edited this page Feb 27, 2013 · 42 revisions

First, make sure you have all of the kit parts. Review the BOM (bill of materials) here.

All of those little parts you have will need to be soldered. If you are new to soldering, check out our soldering quickstart tutorial here. Here are the tools needed (not included with the kit):

The PCB (printed circuit board/big red board) has component value labels and polarity indicators. BE CAREFUL OF POLARITY!! If you are unsure of the orientation of the component, refer to the finished board image below.


For some extra help with the assembly, check out our Friday product post video that goes over the fabfm assembly.

*Notice the limited edition 2-D hologram/silk mistake on the PCB. If you receive one of these boards, feel special, because we will be fixing it soon.

STEP 1 - PCB Assembly

Now we can start assembling the PCB. Fire up the soldering iron and have your cutters handy.

You are going to want to solder everything EXCEPT the speaker.

Let's start with the small non-polarized capacitors. Find the single 1nF cap and separate it from the other 0.1μF capacitors, they look very similar (see image below).


Install and solder the 1nF cap first, then solder all the other 0.1μF caps. Refer to the value labels on the PCB.


The image above has all of the 0.1μF caps and the 1nF cap soldered.


Be sure to clip the exposed leads off of each part after soldering.

After you have the small caps soldered, move onto the resistors. To figure out which resistors are which, use a resistor color code chart. Or refer to the image of the finished board.

Next move on to the polarized capacitors.


You can match each polarized capacitor with its place on the board by referring to the component value label on the red board and looking at the value label on the part itself. For example, the above image shows the 10uF cap correctly oriented and soldered.

Also, be sure to line up the negative stripe on the cap, to the negative stripe on the PCB (see image above).


Now grab the radio module board and solder the 10-pin header.


Then solder the module to the main PCB. PAY ATTENTION TO THE POLARIZATION! Line the VCC and GND pins up.


There are a few other parts that are polarized. Go ahead and solder them and refer to the above picture for the orientation. From left to right: Si4703 radio module, ATmega328, LM1117 voltage regulator, and the LM386M amplifier.

If you are having trouble keeping the ATmega328 to stay in place while soldering, the pins can be bent slightly to hold the IC in place.

Now, go ahead and solder the barrel jack, encoder, and potentiometer. Make sure the encoder and pot are aligned and sitting flush against the PCB. Also, remove the nut and washer from the encoder and potentiometer, they are not needed.

Here is what your board should like now.


Next, we need to cut the 20 inches of red wire for the speaker and antenna. Suggested lengths are 12 inches for the antenna and 4 inches each for the + and - of the speaker wire. This doesn't need to be exact, although the longer the radio antenna, the better.


Strip a small amount of insulation from one end of the 12 inch piece of wire and solder it to the pin hole on the radio module labeled ANT. Hold the remaining 8 inches of wire to the side for now.

Note: You might notice, there are two components that are not populated on the PCB, these are the DNP-330 and the LED. If you would like to add an LED, refer to the modification section.

STEP 2 - Fitting Enclosure

Now we can start assembling the PCB into the enclosure.


First, get the front side of the PCB into the front panel. Make sure you are using the correct orientation of the panel; the encoder and pot have alignment pegs. Also, you might need to bend the housing out to get the PCB to fit over the mounting holes, then push the housing over the pot and encoder.


Now press the top three struts into the front panel, then add the back panel. Be sure to press the struts all the way through. The fitting is supposed to be tight, be patient and wiggle the joint to get the wood all the way through. The bottom struts snap in from the underside.

STEP 3 - Testing Sound

Now we need to add the speaker. Use the remaining wire and cut it into two piece for the speaker connections.


Now solder the two pieces of wire to the speaker after stripping both ends. You don't need to worry about polarization for the speaker, you can solder each wire to either speaker pin. Next, drop the speaker wires through the front hole, flip the enclosure over so that the speaker is resting on the table and not flapping around, then solder the speaker in place.



You can run the antenna wire over the struts to get good reception. You are now finished with soldering and your can now turn your iron off.

Unpack the 9V wall adapter and turn on the radio to make sure everything works. If you’re rocking out to Tears for Fears then you’re doing great! If your radio is not working, unplug the wall adapter and double check that all the solder joints look good and that all the components are soldered in the correct orientation. Also, check the troubleshooting section.

STEP 4 (optional) - Adding Fabric

Hey, we know you really want to get this thing together and see it work, but if you skip the fabric step there is no way to put the fabric on at a later time. Once you put on the face panels, this thing does not come apart easily. There is a very good possibility you will not be able to disassemble the unit without damaging it. If you really want to test your kit out, feel free to plug in your radio now and play a bit and then get back to putting the fabric on.

For the best sound (and looks), you can cover the speaker and outside of the radio with a material of your choice. This step needs to be done before affixing the outer veneer panels. If you don't want fabric on your radio, skip this step and move on to step 5.

Fabric lining

fabfm-sf fabfm-cloth

The one on the left used a SparkFun t-shirt cut from the template below, along with wood glue to get everything nice and tight. The one on the right was done without glue and using non-stretchable cloth cut from the template below.


Stretchable fabric and wood glue works the best. Be very conservative with the amount of glue, you don't need much to hold the fabric to the wood. And just a drop of glue on each strut works just fine to seal everything up. Also, notice how the fabric is stretched around each strut. The template dimensions are not exact, so the best way to cut the holes is to stretch the fabric over the strut, then get a razor knife and cut the fabric to allow the strut to punch through. This way, everything looks nice and tight.

Paper lining

You can also use an old map or any type of paper, to cover the outside of the enclosure.




Here are the template files (jpg, svg, and pdf) for cutting fabric:

STEP 5 - Finishing Touches


Here is an example without a fabric covering.

The final step is to snap on the outside panels and knobs. Remember, the press fittings are supposed to be tight and the enclosure should snap together. If the joints are a little tight, take your time and wiggle the fittings together. The wood is very forgiving. Also, repeated dis-assembly of the wooden enclosure is not suggested, since it will loosen the joints. However, if the joints become too loose, some wood glue will sure everything up.

Now, all you need to do is power the radio and you should be able to tune to FM stations! No programming required (if you are in the US). Be sure to read the Functionality section to get all of the details on how this thing works.

Congratulations! You should now have your very own custom FM radio!