This is an Instructable to make a very low tech timer switch. mine goes off once every 12 hours for about 3 minutes. I made this because i not really that good with electronics but still wanted a cheap timer. This is just the prototype and i hope to make a much more permanent one when i have the time, the plan is to use it to automatically turn on my solar powered irrigation system in my greenhouse. That might be my next instructable.
Oh and by the way, this is my first instructable so any comments would be welcome.
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Step 1: Tools and Parts.
The tools and parts I used where what I had lying around. This made this project free and also green as i recycled some parts
soldering iron holder
solder sucky thing (don't know what its called)
multi-meter (although i don't actually think i used it but thought i might so took a photo of it)
Paddle lever switch or something similar
c.d. or d.v.d
motor or LED
Step 2: Remove the Switch From Circuit
The idea of this timer is for the hour hand of the clock to hit the switch as it passes and completes the circuit. The switch i used was from an old cd player. This meant i had to take it off the circuit board. To do this i heated up the solder with an soldering iron and sucked it away with the sucking tool. The the switch would just fall out. After i got the switch out i then sanded a tiny aounf off one of the corners.
Step 3: Lining Up the Switch and the Clock.
Glue the c.d to the clock movement. I had to put a rubber washer in between them to make the hands at the same height as the switch so this might be something to check before gluing. Then stick the switch inline with the hour hand. Alliteratively if you want the timer to go off every minute then put the switch inline with the second hand, or every hour put it inline with the minute hand. On the picture you can see that i have put the sanded corner of the switch near to the clock hand to make it press it easier. At first i only used tape to secure the switch as i wanted to make sure the it all worked.
Step 4: Make a Test Circuit
Make a very simple circuit. I used a small motor but an LED would just work as good. Any electronic device would work so long as its easy to see when the circuit is completed. This is just to test the switch to see how long the circuit is completed. Mine is about 3 minutes but different switches and clock movements may have different times. On the picture below you can see the 2 wires that are to be connected to the switch on the cd.
Step 5: Solder the Wires and Test.
Solder the wires to the switch and then set the hand just before the switch. Hopefully in the next few minutes the clock hand should turn on the circuit. If it does not then the position of the switch may just need to be adjusted. If it all works then just glue the switch into place and then find a use for this timer.
This is probably not the best way of making a timer as i'm sure a pic chip could do all this and take up a fraction of the size. But for a really cheap easy timer i found this to be just fine. If you do use this idea of a timer i would love to hear what you used it for or any improvements you may have.
Thanks for reading. :)