The Path of a Solder Man (part 4)-Building an FM Radio

I recently bought an FM Radio kit made by Velleman-Kit and sold by Radioshack.  I have not had time to build it but this Thursday, I sat down, played some Doctor Who on my Kindle Fire HD, and built this kit with my solder iron and solder.  Total time took me two hours (the reason for this is because I kept getting distracted with Doctor Who).  The instructions are fairly easy to understand, however, instructions are not explicit in that you have to make the connection to solder the components to their respective position.  I’ll try to explain as close as possible how to build this fun little project.  The components that came with the FM radio kit are as follows.

FM radio components


22 ohms (red, red, black) X 2

10,000 ohms (brown, black, orange) X 2

2,200 ohms (red, red, red) X 3

820 ohms (grey, red, brown) X 1

68 ohms (blue, grey, orange) X1


1N4007 X 1


1µH X 1

IC Socket and ICs

14 pin socket X 1

14 pin TBA120U X 1

8 pin socket X 1

8 pin LM386N X 1


150pF X 1

220pF X 1

22nF X 2

100nF X 4

Voltage Regulator

UA78L08 X 1


on/off X 1

Other FM components


Red 3mm X 1

Capacitive Trimmer

100pF X 1

DC Jack

12V DC X 1

Electrolytic Capacitors

100µH X 5


10K X 2

FM Front End


Custom Circuit Board

(I don’t know how to order this, one came pre-made in the Velleman-kit)

Step 1: Solder the Resistors

Resistors soldered on

The diagram tells you which resistor to solder to which circuit position on the circuit board.  For example, the 22 ohms resistor should be soldered on R1 and R2 positions on the circuit board.

Step 2: Solder the diode

There is only one diode you have to solder on and it is on position D1.  Make sure that you watch the polarity because if it is inserted wrong, it will not work.

Diode soldered on

Step 3: Solder the choke

Only one choke needs to be soldered and its position is on L1.  Polarity issues should not matter.

Insert the choke

Step 4: Solder the IC sockets

Because of the tiny pins located on the bottom of the IC sockets, you must be very careful with soldering.  There is a chance you can use to much solder and cause a solder bridge between pins.  The 14 pin socket is in position IC1 while the 8 pin is in IC2.  Make sure the position of the notch on the socket matches the diagram on the circuit board.

IC Sockets

Step 5: Solder the capacitors

Capacitor polarity does not matter.  Solder the capacitors in the correct positions.  150pF=>C4, 220pF=>C5, 22nF=>C6 and C7, 100nF=>C8+C9+C10+C11.

Capacitors soldered on

Step 6: solder the voltage regulator

Make sure that the regulator goes on position VR1 and also that the flat portion of the regulator is on the same side of the flat line diagram on the circuit board.

The voltage regulator is on!

Step 7: The Switch

The switch is fairly easy to put on since there is only one way to solder it.  Make sure it is in position SW1.

The Switch

Step 8: LED

There is only one LED in the kit and the manual says it should be put on LD1 position; however, on my board there is no LD1 position so instead put it in the position that says ON.  Make sure the cathode (the longer lead) is inserted in the hole that has the white stripe.

LED and the ON position

Step 9: solder the capacitive trimmer

Solder the trimmer in position CV1.

Capacitive Trimmer

Step 10: Solder the DC Jack

Similar to the switch, the DC jack can only be solder one way so it should not be too difficult to solder.  Make sure it is on the SK2 position.

Step 11: Solder the Electrolytic Capacitors

These are a different type of capacitors than the ones used in step 5.  These are placed in positions C1, C2, C3, C12, and C13.  Make sure that the cathode is placed through the correct hole or else it might not work.

The almighty electrolytic capacitors

Step 12: Solder the trimmers

The trimmers soldered are used to adjust the FM station tuning and the volume.  Volume should be on RV1 and tuning will be on RV2.


Step 13: Solder the FM Front End

The FM Front End is given by Velleman so I do not know if one can make their own.  The position to solder this is on is the designated area.  Basically, you will know where it is by looking at the circuit board.

Install the FM Front End

Step 14: Insert the ICs

Remember the IC Sockets we soldered in step 4?  We now insert both the 14 pin and 8 pin ICs into the sockets.  Make sure the notch matches the same notch side on the sockets.

IC in the IC socket

Step 15: insert the speaker and final assembly

The last step is to install the speaker onto the circuit board, mount it using the screws and nuts, then connect the positive and negative terminals of the speaker to the circuit board, and finally solder on the black wire that will act as the antenna.  Should be fairly simple and by this time you should be fairly familiar with the circuit board to know where these components need to go.

Insert that Speaker

Congratulations, you are done!


By this step you should be done with your FM radio and the only thing that needs to be done is plug in a 12V power connector, turn the radio on, and tune in to your favorite FM station.

Need the circuit schematic diagram for reference?  You can find it by following here

That project was very fun to make and it was a good starter project to get someone into the world of soldering.  Have a project you want me to try?  Let me know by commenting below.


One thought on “The Path of a Solder Man (part 4)-Building an FM Radio

  1. Pingback: The Path of a Solder Man-Turning AC to DC | The Layman's Guide to Electronics

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