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Sunset Alarm Clock Problem May 20, 2010

Posted by Tom Frobish in Physical Computing.

Ok, so I’m making this alarm for my physical computing class that basically wakes you up by turning on a high powered light that would rotate over your wall or your body to create a false sunset for those of you who wake up to light.

Basically what I’ve been working on was taking an alarm clock, my trusty arduino, a wireless wall switch and relay, a 4′ 2000 lumen led flourescent replacement bulb, some servos, and some pvc tubing.  In a very fast summary, my friend Jason and I wired them together and pressed a couple of keys in the keyboard to tell the light to turn on and swivel when the arduino recieves signal the alarm going off.

So far, I have not finished the project because for some reason, I have been very retarded and couldn’t find the right signal off of the alarm clock board that triggered the speaker to go off.  I kept thinking I can use the buzzer lines themselves but was very confused when I found that they had a constant 3.2 volts running through the line when the buzzer wasn’t going off and when the buzzer did go off, the voltage dropped down to 2 volts which baffled me for a very long time.  Then when I called my dad to see if he knew what might be happening, he said to try checking it on AC current and I was like…uh ok, when I did skeptically, I the voltage jumped up to 1 volt AC when the buzzer went off, which means it really wasn’t a buzzer, but an actual speaker (which runs off of AC current, not DC) which would explain why it wasn’t making any noise when it had 3.2 volts running through it.

After a lot of searching for the trigger signal coming out of the little microprocessor, I couldn’t actually find a line that jumped up to a high when the alarm went off.  Every line that had voltage change went from a constant high and dropped down to a low.  So I decided instead of trying to find a high to signal the arduino, I would just tell it to send out a low signal to to wireless transmitter when receiving a high and send out a high when it received a low from the alarm clock.

Then after being braindead and having a cheapass soldering iron, I went on to surface mount a lead off of one of the resistors (normally this would be peace of cake if I had the right tools and was in the right mind) but I had a cheap soldering iron with a blunt pencil tip and because of it’s low heat, I had to hold it onto the board for an extended amount of time (don’t worry, I used flux) and it heated the other resistors around it and caused a few to pop.  Then Murphy’s law kicked in hardcore because after that happened, I managed to get them soldered back on.  After that, the wire I leaded off of the other resistor (was an 18awg wire solid core, that’s all I had at the time) broke off and took half of the resistor with it.  After just staring at what just happened for a few minutes, I figured “Well shit, maybe if I just solder the two halves together, maybe the board won’t know.”  and I think between that and popping some of the other resistors and heating the other components up I figured and broke something or shorted something else because when I go to check the clock, now it’s got a power drain somewhere because the line that was supposed to be outputting 3.2 volts was putting out 2.6 volts and didn’t drop when the buzzer went off which was totally awesome!

Anyways, I summarize the rest of the project, when the alarm clock went off, it would tell the arduino it was beeping, then the arduino would switch a transitor on the wireless switch which would flip the latching relay hooked into the wall to turn on and turn the light on.  When that would happen, the arduino would then tell the servos to run their script (which was slowly rotate the bulb of the bed and blind the sleeping person awake.



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