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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?

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westfw

10 years ago

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 :-(

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gimmelotsarobots

10 years ago

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.

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tech-kinggimmelotsarobots

Reply 10 years ago

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

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guyfrom7uptech-king

Reply 10 years ago

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.

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tech-kingguyfrom7up

Reply 10 years ago

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

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tech-kingtech-king

Reply 10 years ago

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

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guyfrom7up

10 years ago

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.