This is the second Sports Timer I have built. See my first build here.
My uncle liked the timer I made for my grandpa and wanted a timer for himself because he also runs hockey games.
I started by taking apart the horn case and adding a conduit wire clamp.
Then adding the power wire.
I tied a knot in the wire to help prevent pull out and shorts.
The switch is wired up now.
here is the timer circuit with the resistors replacing the pot. I do this to keep the timer accurate.
These are the raisers I used to prevent the circuit boards from shorting out.
Side view of circuit raisers.
I also added these double stick foam pads.
I added the circuit board and 12V relays to the electrical box.
This is a 12V power supply. 120V AC goes in and 12V DC comes out. This will power the 12V relay and 12v circuit board timer.
The 12V relay turns on and off the 120V AC buzzer.
The 12V power supply is wired into the 120V AC coming from the power switch.
I needed to fabricate the legs to hold up the buzzer.
I think I went with a 30 degree angle.
I welded it to the electrical conduit box on the back of the buzzer.
I also made the handle on the top by bending an old handle and welding it.
Now back to the wiring. The 12V power supply circuit board is covered in heat shrink to protect it from shorts.
Wire is all connected.
I added labels to the power switch positions while I was testing the timer. The time was off because the resistance varies between timer circuits so it was not the same value as my last timer.
I used alligator clips and tested different resistors and the times.
The old resistors are removed.
Now the new ones are soldered in place.
Everything is put back in place and tested again.
The timer is now set to the correct timer!
Here is my wiring diagram for the hockey / Sports timer.