Police Strobe Siren
Parts:
18 Volt Drill
12 Volt Siren
Large Plastic Fitting
Adjustable Voltage Regulator
2x Red Blue Strobes
Momentary Button
2 Pin Connector
nuts, bolts, Some scrap Metal
Disassembly:
Taking apart the drill is very simple. You remove the 8 screws from the case and set them aside. Once all the screws are out you can separate the two sides of the casing. You will now have access to the motor and switch assembly. You can cut the two wires that connect to the drill motor and remove the motor from the housing. Set aside both half’s of the case for now.
Mounting the Strobes:
I decided to mount the strobes on each side of the drill housing. This makes the over all size small and keeps them sticking out in an awkward way. I found two pieces to metal scrap that were perfect for mounting the lights to the drill. I started by drilling three holes to bolt the light to each piece. There are two to actually secure the strobe to the place and one larger hole drilled in the center to feed the wire thought the place. I then drilled two holes in the top block of metal for mounting, These go all the way thought I then took a larger drill bit and drill in to the holes so that the bolt head could fit into the block. I made the larger holes go about half way in to the block. To make the cabling just a bit neater I used a cable manager clip and zip tie to secure the cable on each block.
To attach the new assembly’s to the drill housing I drill 2 holes in each side of the drill case that matched each hole in the blocks. I then put the screws in to the block and install two spacers before pushing the bolts thought the casing. Next I installed the nuts and tightened both bolts down on each side of the casing. The spacers just add a little bit of space between the grip and the lights making it comfortable to hold. The last thing I had to do was drill a small hole in each side of the case to press the wire thought.
Wiring:
The strobe’s I choose are compatible with 18 volts, I wanted the siren to run off of 12 volts because in a different design I used 18 volts and it made the motor spin to fast. To solve this problem I ordered an adjustable voltage regulator capable of handling three amps. A quick disconnect was added between the regulators output and the motor for the siren, This allows me to disconnect the siren if I just want to have the strobes being used. The strobes also have nine patterns to choose from, I installed a momentary switch that connects the selector wire to the positive voltage to allow the pattern to be changed quickly. There are two wires coming from the trigger assemble, These are the positive and negative sides. I connected the positives lines from the battery, the voltage regulator, both of the strobes and one side of the button all together. I did the same for the negative lines except for the button, and the last group of wires would be the two selector lines from the strobes and the other side of the button. I twisted each in to a group and soldered them together and covered that in heat shrink tube. For the output of the regulator I connected both wires to the connected I added for the motor making sure I installed the both to secure it in place first before soldering and heat shrinking these wires. I last wire that needs to be placed is the other end of the connector, This is threaded thought a hole in the drill casing and soldered to the positive and negative of the motor. At this point you can put the battery in to the drill and when you pull the trigger you can make sure that the siren spins up and the strobes fire, When you press the button on the back the strobe patterns should cycle thought.
Mounting the Siren:
The siren I used has a removable shell around the motor, this and the bracket were both removed. I also de-soldered the wires from the motor. In order to mount this to the drill casing I found a plastic coupler from an enclosure, it was threaded and just slightly larger then the motor. With a little tape on the threads this fit perfectly in the open end of the drill housing. I slipped the motor of the siren in to this plastic sleeve and after pre drilling three holes I put in three screws to firmly attach the siren to the coupler. The would sit firmly in side the drill hosing but just incase I drill two holes with it in place and threaded in two screws to lock it in place, this will prevent it from twisting or coming loose.
Finishing and testing:
To finish up this project I made sure that all the screws were tight and nothing was moving in the drill housing. With the battery installed, pulling the trigger will begin to fire the strobes and spin up the siren until you let it go. With the trigger pressed you can push the red button on the back to change the strobe pattern on the lights.
