How to Build an FM Radio Receiver

By John Mitchell

Building an FM radio receiver is a project you can complete at home in a few hours. Once completed, you'll have a fully functional receiver that can tune at least 20 FM stations from 87 to 107 MHz. On this home-made FM receiver, the signal-to-noise ratio rivals factory manufactured portable radio tuners. You can find most of the parts needed at your local Radio Shack or electronics store.

Things You'll Need

  • FET transistor
  • Magnet write set
  • LM386 low-voltage audio power amplifier, 8-pin
  • 8-pin retention contact
  • Panel mount jack
  • SPST Micromini toggle switch
  • 10K Ohm horizontal-style trimmer
  • 1K Ohm horizontal-style trimmer
  • 10uF/35v electrolytic capacitor
  • 100uF/35v electrolytic capacitor
  • 220uF/35v electrolytic capacitor
  • .01uF Ceramic disk capacitor
  • .0047uF Ceramic disk capacitor
  • .047uF Ceramic disk capacitor
  • .1uF Ceramic disk capacitor
  • PC board kit
  • Duraban headphone radio
  • 9-volt snap connector
  • 3-piece anti-static set
  • 8-by-6-by-30-inch enclosure box
  • Soldering gun
  • Nuts and bolts

Step 1

Gather all parts and tools before starting.

Step 2

Create the source and drain coils. Wrap copper magnet wire 26 times around a 8 mm non-metallic form. This will be the source coil. Then wrap the copper magnet wire seven times tightly around a 2-inch-long, 5/16-inch threaded bolt.

Step 3

Begin to drill holes and solder the parts in place using the Chart I diagram. (See Resources)

Step 4

Drill a hole on the PC board in spots Nos. 2 and 15 as listed on Chart I. Also, enlarge holes at spots Nos. 17 and 23.

Step 5

Place the 8-pin DIP IC Socket into the eight holes at spot No. 10. Flip the board and solder the part from the reverse side.

Step 6

Connect and solder the following parts in their respective locations:10uF/50v capacitor at spot No. 13.100uF/10v capacitor at spot No. 14.

Step 7

Attach and solder the two .047uF ceramic disc capacitors at spots Nos. 16 and 21.

Step 8

Drill a hole at location No. 22 for the "On/Off" switch.

Step 9

Place the 1K potentiometer at spot No. 25 and 10K potentiometer at location No. 11. Solder the parts on the reverse side.

Step 10

Attach the FET transistor in spot No. 4. Push the legs firmly into three holes on the PC board.

Step 11

Attach the .001uF ceramic disc capacitor to spot No. 26. One leg goes to the drain coil and the other goes to the ground current. Flip the board over, then solder in place.

Step 12

Connect the 15pF ceramic disc capacitor at spot No. 1. Then take the ground to the lower terminal at place No. 28. After that, solder the part in place on the board's back side.

Step 13

Take the 5pF ceramic disc capacitor and place it at location No. 5, connecting one leg to the drain coil and the other to the source coil.

Step 14

Attach the .0047uF ceramic disc capacitor at location No. 7, connecting one leg to the source coil and the other leg to the ground current.

Step 15

Location No. 8 is for one of the 10K resistors. Connect the legs between the .1uF ceramic capacitor and the .0047uF ceramic capacitor. Then solder.

Step 16

Location No. 9 is the 1uF ceramic capacitor. Connect both legs to the 10K potentiometer. Item #12 is a .01uF ceramic capacitor and the one leg goes to the middle leg of the 10K potentiometer. The other leg goes to the ground current. After attaching, solder these parts.

Step 17

Attach the drain coil at spot No. 27 and source coil at place No. 6. Use a dab of super glue to keep both coils securely fashioned onto the board.

Step 18

Put the audio jack on the board, connecting the terminals to locations Nos. 18 and 19. Use the Audio Jack Chart (See Resources). Insert the "On/Off" switch into location No. 23.

Step 19

Connect the variable tuning capacitor to location No. 28. Finally, connect and solder your antenna at place No. 3. Once completed, turn on the radio. Tune the receiver until you locate a clear FM channel.