How to Make a Radar Gun

A radar gun can come in handy when you want to track the speed of an approaching car or how fast your son is pitching a baseball. A toy radar gun using Doppler radar does not have the power or efficiency of an expensive professional radar gun. Converting a toy radar gun into a fully functioning radar gun can be accomplished within an hour or two and will give you the capabilities that radar guns used by professionals enjoy.

Things You'll Need

  • Toy radar gun
  • Electric drill
  • Phillips screwdriver
  • Drink bottle
  • Hacksaw
  • 1/4 inch x 20 coupler nut
  • 1/4 inch x 20 bolt
  • Washers
  • Mini toggle switch
  • "AA" battery holder
  • Mint tin
  • Small rotary tool
  • Black paint
  • Brush
  • Soldering iron
  • Solder
  • Bonding glue
  • Tripod mount
  • Drill out the plastic caps covering the screws of the toy radar gun. Remove the screws with the Phillips screwdriver and put them aside.

  • Pull the top casing of the toy radar gun off. Make a note of the positioning of the wave guide housing and the wiring connected to the display, the switch and the battery holder in the bottom casing. Disassemble the wiring and remove the parts from the bottom casing.

  • Take the drink bottle that will serve as the new wave guide housing and cut off one end with the hacksaw.

    Drill two holes on two sides of the bottle, each one about halfway down the length of the bottle and across from the other.

    Drill two holes on the back of the bottle, one at the left edge of the back of the bottle and the other at the right edge of the back of the bottle.

  • Paint the closed empty mint tin black. Let the paint dry. Use the small rotary tool to cut a square hole in the mint tin to hold the "AA" battery holder.

    Glue the battery holder into the mint tin hole with the bonding glue.

  • Solder the wiring from the display to the mini toggle switch.

    Attach the tripod mount to one hole in the side of the bottle and solder it into place. Attach the mini toggle switch to the hole on the other side of the bottle and solder it into place.

  • Put the bolt through one of the holes in the back of the drink bottle. Drill holes in the mint tin to correspond to the holes in the display.

    Run the battery wires from the mini toggle switch through the other hole in the back. Solder the wiring to the contacts on the battery holder and to the wave guide.

    Drill a hole in the wave guide to correspond to the bolt.

  • Run the bolt going through the back of the bottle into and through the hole in the wave guide and the mint tin. Secure the tin against the wave guide using the washers and coupler nut.

  • Screw the display to the mint tin using the screws from the display.

  • Drill holes in the bottom casing to correspond to the mini toggle switch at the top and the tripod mount at the bottom.

    Place the drink bottle into the casing of the radar gun with the display sticking out from the end; the mini toggle switch and the tripod mount should go through the holes in the casing (at the top and the bottom, respectively).

  • Put the top casing back onto the radar gun. Screw the two casings back together.

  • Place the radar gun on a tripod. Turn the mini toggle switch to the On position and enjoy using your radar gun.