267Views9Replies

Author Options:

Light Alarm Clock Help Answered

I want to build my own version of the the Progressive Light Alarm Clock by Phillips found here. Theres several of these products on the market, but most are $100-200. Does anyone have any ideas of how to make one yourself?

9 Replies

user
westfw (author)2008-04-06

If the idea is to simulate sunrise, I think you'll need to control lights that are brighter than (conventional) LEDs. An interesting idea is to tie a traditional microcontroller alarm clock into an X10 controller, so that it could brighten any light (or combination of lights?) connected to X10 switches. The gradual brightening is an interesting idea. I have my doubts, though; I had my light set on a timer switch to (supposedly) help me wake up back when I was in high school, and it didn't help much. I still sleep better in the daytime than at night anyway :-(

Select as Best AnswerUndo Best Answer

user
gimmelotsarobots (author)2008-04-05

When the trigger for the alarm activates, 2 555 timers (one as a one shot, and one to control LED brightness) would slowly wake you up. Not sure what to replace the potentiometer in the brightness 555 with. Maybe a FET? correct me if I'm wrong.

Select as Best AnswerUndo Best Answer

user

not an jfet. a mosfet. you could use a mosfet. by varying the gate voltage, you could use it as a solid state variable resistor. youd need a circuit that gradually adds voltage to the gate though. an rc integrator may work, or it will cause the light to flash rapidly. either way, it would be fun. you could probably dump the 555 timer though

Select as Best AnswerUndo Best Answer

user
guyfrom7up (author)tech-king2008-04-06

you could use a jfet, a jfet and a mosfet are almost the same, it's just that mosfets are more fragile and take less current to turn on/off.

Select as Best AnswerUndo Best Answer

user
tech-king (author)guyfrom7up2008-04-06

no, you could not use a jfet. you need a real mosfet for this. with a jfet, the power from the source to the drain is fully on when the gate voltage is 0. as the voltage drops, the field effect is greater, and the resistance goes up. the main use of jfets is in amps, where their high impedance is needed on the input side. on a mosfet, as the power at the gate goes up, the power from the source to the drain goes up. (this makes it easy to build a vcr off a mosfet) and mosfets use about a trillionth of a milliamp of current. however, like all semiconductors, they need about 0.6VF

Select as Best AnswerUndo Best Answer

user

I new there was a fet in the name. couldn't remember which one...

Select as Best AnswerUndo Best Answer

user
tech-king (author)tech-king2008-04-06

ohh, hang on. i forgot: to make the integrator run, youd need a zener diode waveform clipper and a source of 9 VAC

Select as Best AnswerUndo Best Answer

user
guyfrom7up (author)2008-04-05

I'd say the best solution is to take a normal alarm cclock, take it apart, desolder the piezo/speaker. make it trigger a 555 in astable mode to charge a cpacitor, hook up leds (with a resistor) to the capacitor. the 555 should charge the cap a tiny bit faster then the LEDs drain it. That might just work.

Select as Best AnswerUndo Best Answer

user
Goodhart (author)2008-04-04

If I were attempting this, I would probably do a MASHUP of an alarm clock with a mood light like this one or similar

Select as Best AnswerUndo Best Answer