Instructables
Picture of Sunrise Alarm Clock

Many people find the beep of an alarm clock to be a very unpleasant way to wake up. One alternative is to use lights to wake you up. For instance, a "sunrise alarm clock" gradually increases the brightness of a light near your bed at the set time. This helps some people to wake up more gently. 

So in this project I am going to show you how to build a light alarm circuit from a outlet timer and a hand full of basic electrical components. 
 
Remove these adsRemove these ads by Signing Up

Step 1: Materials

Picture of Materials
Here are the materials that you will need to make the circuit:

AC Light Timer
USB Cable
USB AC Adapter
IRF510 MOSFET
1 Mohm Resistor
4 X 100 ohm Resistor
10 kohm Potentiometer (Variable Resistor)
1000 µF Capacitor
4 X LED
Printed Circuit Board
Jumper Wires
Extension Wire (optional)
Momentary Switch (optional)

You will also want to have the following tools at hand:
Soldering Iron and Solder
Wire Strippers
Wire Cutters
Non-Conductive Tape

Step 2: The Circuit

Picture of The Circuit
Image10 with snoozeJPEG.jpg
This circuit is essentially just a resistor/capacitor timer with a transistor amplifier. The capacitor is initially discharged. When the power is turned on, the capacitor begins to charge through the 1Mohm resistor. As this is happening, the output voltage of the capacitor slowly increases. This voltage signal is sent to the transistor which sets the transistor's output. This causes the LEDs to gradually increase in brightness over several minutes.

The potentiometer (variable resistor) is used to adjust the starting voltage of the capacitor. This effectively lets you set the initial brightness of the LEDs. Without it, the LEDs would be off for a long period of charging before the output would be high enough for LEDs to begin to emit light.

The values of the 1000 µF capacitor and the 1 Mohm resistor were arbitrarily chosen for convenience. Increasing either of these values will slow down the charging process and cause the LEDs to brighten more slowly. Decreasing either of these values will have the opposite effect.

The IRF510 MOSFET was chosen for the transistor because it requires very little input current and is capable of driving a large number of LEDs.

Optionally, you can connect a normally open momentary switch to the two terminals of the capacitor to act as a snooze button. Pressing the button will drain the capacitor and restart the charging cycle.


Step 3: Assemble the Circuit

Picture of Assemble the Circuit
vlcsnap-2013-08-07-22h17m26s115.png
IMG_5134.JPG
Following the circuit diagram in the previous step, I prototyped the circuit on a breadboard. When testing the circuit, remember that you need to discharge the capacitor between each trial. The LEDs brighten as the capacitor charges. If it is already fully charged then they will stay at a constant brightness.

After testing the circuit to make sure that everything was functioning properly, I soldered the circuit together on a printed circuit board. I decided to add a few more LEDs to make it a little brighter. Then I trimmed the circuit board to fit. Depending on how you plan to mount the lights, you may wish to add additional wire so that you can reach areas that are further away from the outlet.

Step 4: Mount the Circuit

Picture of Mount the Circuit
IMG_5107.JPG
IMG_5126.JPG
IMG_5122.JPG
IMG_5159.JPG
There are a lot of ways that you could mount the light. The simplest way is to just place it next to your bed on your night stand. This can work but it is less effective if you are facing the other direction. Another option is to mount it over your bed in something like a hanging lantern. If you want the light to be more directional, you can mount it in an adjustable lamp that can be pointed at your pillow. If all else fails you can put the lights directly into a pillow, such as "Bright Light Pillows." Do whatever works best to wake you up.

Step 5: Set Up the Timer

Picture of Set Up the Timer
Plug the timer into the wall outlet. Plug the USB AC adapter into the timer. Then plug the USB cable into the adapter. Set the timer to turn on about 15 minutes before you want to wake up. When the timer goes off, it will activate the circuit. The LEDs will then gradually turn on and hopefully wake you up. 

Step 6: Finished Sunrise Alarm Clock

Picture of Finished Sunrise Alarm Clock
IMG_5144.JPG
Now you have your own DIY sunrise alarm clock. When you are first trying it out, you may wish to have a regular alarm as a backup just in case the light doesn't wake you up reliably.
1-40 of 49Next »
djerome14 months ago
I made this yesterday and it worked great. I had 7 ultra bright LEDs each at about 30 mAmps and combined in this circuit I estimated their brightness to be about the same as a 30 watt incandescant. The circuit as posted increased in brightness over approximately 10 minutes and an additional 1MOhm resistor in series with the first doubles that time to about 20 minutes. I want mine to be brighter than what it is so I intend to add more LEDs. I think I may have to have two separate circuits eventually though as mentioned in another comment that the capacitor and pot can only handle so many. My power supply is a transformer from a Nintendo DS and outputs 4.6V and 900 mAmps. Does this means I should be able to run a total of 20 to 30 LEDs off this in multiple parallel circuits?
Thanks for the simple!
DIY Hacks and How Tos (author)  djerome14 months ago
Yeah. Just take the capacity of the power supply and divide by the load of each LED and you get a rough approximation of the number of LEDs that you can have.
djerome1 djerome14 months ago
"Thanks for the simple circuit!" I meant to say.
etcmn6 months ago

Thanks, I've been looking for a gradual light alarm. As several others have mentioned I would like to know how to upscale it. I have a couple hundred 3V 50ma LEDs. I would like to set this up so it goes from dark to the equivalent of a 60 watt incandescent over about 20-30 minutes.

The Freak8 months ago
Love the idea, building one with a total of 20W of power LEDs. Might make an instructable about it, naturaly with credits to you ;)
DIY Hacks and How Tos (author)  The Freak8 months ago
Good luck. Let me know how it turns out.
Does your capacitor discharge itself in a day?
DIY Hacks and How Tos (author)  The Freak7 months ago
In most cases it will discharge in a day. If you want to speed up the discharge you can put a large resistor in parallel with the capacitor.
Oh damn never mind, I'm an idiot. It discharges over over the pot and the MOhm resistor in a few hours or so.
mstark29 months ago
I put together the circuit, and it is not working properly. The LEDs will change brightness when I turn the pot, but even after being plugged in for >10 mins the LEDs don't change brightness. The LEDs are not identical; would this cause such a problem? I've had some experience with electronics in school--enough to understand how it works, but not to effectively troubleshoot on my own. Thanks!
jmj16610 months ago
what size cap/pot would be required for a 5 meter LED strip
DIY Hacks and How Tos (author)  jmj16610 months ago
The capacitor and the potentiometer are not effected by the size of the light that you use.
I am having the same problem as jmj166 when I breadboarded this project.
I only get either highest brightness or very dim when I adjust the pot. Also, the LED's do not increase in brightness.
I am a beginner at electronics and thought this would be a good starter project.
Any assistance would be great. Thanks
the more LED's you use will impact the sizes of the capacitor in how long it will achieve full brightness and the pot size in what the initial brightness will be though. Is there a way to calculate the cap or pot size when increasing the number of LED's. When I connect this circuit to a 5m 3528 LED single color strip (white) it just glows at full brightness. When i adjust the pot it only adjusts the dimming a little, so i assume a larger value pot and cap are required to give the same effect as the example here with 7 LED's.

I'm looking forward to (hopefully) figuring this out with your help (if able). I use an LED strip for an alarm clock. As some have commented if 5-10 seconds slowly turning on would make a difference, it definitely would. Imagine having the sum just go to full brightness in your face instantly as an alarm clock. It scares the crap out of you, and will eventually just make you mad.

Anyways, I appreciate the helpful tutorial thus far, I wish instructables had a thumbs up/down option. This is def better than a lot of instructables on here.
EwanWotarmy10 months ago
Thanks for posting this! I appreciate the simple interface with the lamp timer. Very smart. Would you have any advice on running something bright like this off of a battery powered by the sun? A solar sunrise alarm clock, if you will.
plantprof11 months ago
Could this be modified to operate a regular table lamp with, say, a 60 watt incandescent bulb or CFB?  I'm not sure the LED would be bright enough to awaken me since I sleep in different positions and am not always facing the LED source--need the whole room to get brighter.  What modifications would be necessary? Great idea -- have wanted to be able to have the room gradually get brighter when I wanted to awaken for years.
DIY Hacks and How Tos (author)  plantprof11 months ago
This specific design couldn't really be used for large incandescents. You would need to modify a commercial light dimmer. I haven't taken one of those apart yet so I don't really know how it would need to be modified. Sorry. If all else fails you could just buy a commercial sunrise alarm clock.
009agent11 months ago
What voltage capacitor should be used?
DIY Hacks and How Tos (author)  009agent11 months ago
As a general rule, your capacitor needs to be rated for at least as much as your supply voltage (in this case 5V). You can use anything higher and it won't make difference.

So for this project, you need capacitors that are at least 5V.
JustJohn36911 months ago
so good using as my science fair project!!!!!!!!!!!!
Ardutronic11 months ago
Hey Guys very nice project! I love it! It's so hard for me to wake up in the morning, and i think that this will help a lot. I tried to make it on a bred board but it's not working, i don't know why! I used a 1000uF 6,3v capacitor (i tried with 25-30v too) but nothing is still working. There's just a think that i'm suspicious about: i don't find the IRF510 so the guy in the electronic store gives me a IRF520 one and tells me that it won't make any difference. Is that true? Because the in the circuit nothing happend until i touch with my finger the metal piece of the mosfet. Could you please help me? I need this alarm so bad because school will be stared in the next 4 days. Thank you so much!
jimbo1311 months ago
i made a light alarm by connecting a piezo buzzer to a small solar panel and set it in my window, when the sun comes up it starts buzzing.
kiwisaft1 year ago
if you like a sunrise-wakeup more than a bed-on-fire-wakup, do not put it into your pillow
I dont think 5v would set a fire easily
That sounds like the most effective way to wake someone up! :D
An increase over 5 seconds. Does that really make a difference. Wouldn't it be more useful to make the timer itself and a big light?
The LEDs would actually increase in brightness much more slowly than is shown in the video. I greatly increased the speed of the video to better illustrate the process.
How slowly? like over 5 minutes?
I have got an old alarm clock kit, I am going to make something like this with a in-built timer
That depends on the value of the capacitor, the value of he resistor, the setting of the variable resistor and the lighting properties of the LED. You can calculate it. But it is probably easier to just try out different values and see what works. The values that i used went from just starting to be visible to fully bright in about 10 minutes.
That's nice, I might make it, its just when I saw the video I thought it was a bit pointless - 5 seconds is nothing.
Is it possible to change the leds for a 12volt big led light,
Will I need a higher voltage then? like 15 volts?
You can run the system on 12 volts. You just need a 12V supply. I recommend using an old Power adapter with a 12V voltage regulator.
hawkeyejr1 year ago
I would like to see someone come up with an alarm that would go off 5 mins before SUN RISE.
Seemingly difficult, easily done, but practically useless.
Not useless at all if you want to SEE the SUN rise everyday.

Okay, all you need is a real time clock and a lookup table of time of sunrise for each day of the year.
Yes but if someone smarter than you or I could come up with a "light sensing alarm" I could continue to enjoy the sunrise with out changing the alarm, and on cloudy days just sleep in.
Add a photocell.
Is it possible to make a photocell work backwards? All the ones that I have used in the past turn off when light is detected.And I did try to reverse one once;SMOKED IT!
I don't think so, at least not with the CdS type. A photovoltaic will do this however.
Sapper1 year ago
Neat... but isn't gradual light increase what a sun rise is? And isn't this what a window already does? Just saying.
1-40 of 49Next »