Y o s e i f ' s   H o m e P a g e   v 4 . 0

FRS Power

Background

This hack will allow you to run your FRS (or any other 4.5V device from your car power instead of batteries. The adapter itself is very easy to build. The only complicated part is wiring a connector to your FRS. I didn't include a lot of detail there because every FRS is different.

I chose to use 9V-Style plugs because they are low-profile. You could use any plugs your want. You could even do without if you don't need to remove the power adaptor from the FRS.

If you wanted, you could put the enclosure up by the FRS, instead of by the Car Adapter. This would eliminate the need to have a tape-wrapped connection. However, I decided that I didn't want it banging around as I use the FRS.

I have included a wiring diagram (bottom of page) to help clarify the instructions. Those of you that don't need detailed instructions may only need the diagram.

Note: Do not use this adaptor while batteries are in your FRS!


Tools & Supplies

Tools:
  • Soldering iron and solder
  • Small phillips-head screw driver
  • Drill and 13/64" bit
  • Wire cutter/stripper

Supplies: (all part number are Radio Shack)
  • Voltage Regulator (276-1770, $1.49)
  • Diode (276-1101, $0.49)
  • 9V-Style Adaptor (270-325, $1.39)
  • Enclosure (270-288, $1.99)
  • Car Adapter (270-021, $3.49)
  • Electrical Tape
  • White-Out

Steps

  1. Drill a hole in each end of the Enclosure.
  2. Cut the wire about 5" from the Car Adapter.
  3. Use the White-Out to mark the negative side of the wire coming out of the Car Adapter.
  4. Tie a knot leaving about 1".
  5. Cut the remaining wire to about 3 feet.
  6. Use the White-Out to mark one strand of the remaining wire on both ends.
  7. Tie one end of the wire, leaving about 1".
  8. Split the other end and tie one strand to the 9V Adapter leads.
  9. Clip and strip the other strand so it is the same length (re-mark it if necessary).
  10. Solder the marked strand to the red 9V Adapter lead.
  11. Solder the un-marked strand to the black 9V Adapter lead.
  12. Wrap the connection in electrical tape.
  13. Solder the other two marked strands to the ground tab on the Voltage Regulator.
  14. Solder the un-marked strand coming from the Car Adapter to the input leg on the Voltage Regulator.
  15. Solder the un-marked strand coming from the 9V Adapter to the side of the Diode with the white band.
  16. Solder the other side of the Diode to the output leg of the Voltage Regulator.
  17. Clip the unused middle leg of the Voltage Regulator. If necessary, use electrical tape to make sure the leads won't touch.
  18. Put the components inside the Enclosure, making sure the knots are at the drilled holes.
  19. Close the case.
  20. Open up your FRS radio and find the positive and negitave power leads.
  21. Take a new 9V Adapter and solder the black wire to negative and the red wire to positive.
  22. Close up the radio.

Misc

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