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. 

Step 1: Materials

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

AC Light Timer
USB Cable
USB AC Adapter
1 Mohm Resistor
4 X 100 ohm Resistor
10 kohm Potentiometer (Variable Resistor)
1000 µF Capacitor
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

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

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

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

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

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.
<p>So I am brand new to this and I have ordered all of the parts, but the video does not explain how to literally make the clock. Could you make a video or send pictures of the front and back of the breadboard so that I know what pieces connect to what? Also, what do you connect the wires from the USB cable to? </p><p>I would also like to use a mini solar panel to power this. Any suggestions on how to do this?</p>
<p>Here is a tutorial on how to read circuit diagrams. And step 3 has pictures of the front and back of the circuit board. The USB cable provides the power. The red wire is the positive supply voltage. The black wire is the negative. This design is not easy to use a solar panel with because it uses a 120V outlet timer. But you could make a timer circuit that runs on DC.</p>
<p>Hey man! This is a great idea! Thanks for posting this.</p><p>Suppose I wanted to replace the LEDs with a 60W LED lightbulb. What changes would I have to make to the setup then?</p><p>Thanks!</p>
<p>You would need a completely different circuit to work with a 60W bulb. Regular light bulbs are designed to use 120V AC.</p>
<p>and with the solar panel I still want it to work as an alarm clock to wake me up at a certain time...</p>
<p>This is awesome! Here's a more complicated version of the same idea that i put together: http://rampantrobots.blogspot.com/2015/05/i-met-friend-recently-who-mentioned.html</p>
<p>Would this work with a 12V 2.5A 5m LED strip assuming I'd change the power source to one that is capable of producing 12V and atleast 2.5A?</p>
In theory it could work with the right parts. A single power transistor would not be able to handle that big of a load. So you would probably need to multiples or a different kind of controller.
What wattage are all your resistors? I am by no means electrically inclined. If I wanted to double the time it takes to fully come on, what capacitor and resistor combination should I use?
<p>I used 1/8 Watt resistors. The time it takes for the lights to come on is proportional to the resistance times the capacitance. So double either the resistor or the capacitor or some middle combination. </p>
<p>Made this for my fish tank .Used 4 luxeon stars and 9 white LED's (different resistor values) , works great , takes about 10mins . Might play with the values a bit more and maybe figure a night dimmer .Saves me time in the morning now fish have no I-Lids and had to turn all different lights on in order for the same effect . Thank You , </p>
<p>Any reason why I can't put some sort of buzzer instead of the LEDs? Also, I have some transistors that came out of an old power supply. How can I find out if I can use one of them? Will a BJT also work?</p>
<p>A buzzer can work just the same. A BJT can be used in place of the MOSFET but you need to put a 1 kohm resistor on the base pin.</p>
I tried building mine up on a breadboard, and it worked exactly as it should. But I was using some really dim red LEDs I had leftover from a class. So, i switched one of the red ones with a pretty bright blue one. Now they all work fine except the blue. Does anyone know what I did wrong and how to fix it?
The LEDs might have a different voltage requirement. The LEDs that I used were rated for 3 volts. If the new LEDs are a different voltage, then you will need to use different resistor value.
<p>Nevermind... The blue turns on after the reds are bright so.. no problem after all.. Just different voltage rating or something. I think I am going to buy some amber ones to try and make it seem more like sunlight and start soldering the final version!</p>
<p><strong>any alternatives with IRF510 MOSFET?</strong></p>
Power NPN can work but it is less efficient. You just need to add a 1K resistor to the base pin.
<p>what kind of specifications for the transistor?</p>
<p>It must be rated for at least the amount of current that the LEDs will use.</p>
<p><strong>any alternatives with IRF510 MOSFET?</strong></p>
<p><strong>any alternatives with IRF510 MOSFET?</strong></p>
<p><strong>any alternatives with IRF510 MOSFET?</strong></p>
<p>Success! Great project, I can't wait to get a table lamp to put this in. A sunrise alarm clock is crucial for me, since my bedroom gets almost no sunlight. But building my own saved me over $100!</p><p>Using the 1000&micro;F capacitor and 1 Mohm resistor results in a time of approx. 10 min. for the LEDs to reach full brightness. If I were to redo this project I would choose higher values for one or both components to increase the amount of time. </p><p>I used the Big Button Timer by GE as my alarm timer. This thing makes a soft but annoying, continuous sound. If you have to use this timer, plug it in as far away from your bed as possible.</p>
<p>I used 10 LEDs, charges fully in about 20 minutes.</p><p>Thanks!</p>
<p>This is my first circuit board, and I have learned a lot so far but I'm unable to make this work.</p><p>I have narrowed my circuit board down to one LED, and I still can't get light. Is it possible make an insructable with a breadboard that has the number's on it? From certain angles I'm unable to tell where each piece goes.</p>
<p>Just try to make it match the schematic. If you are new to circuit schematics here is a tutorial: <a href="http://www.instructables.com/id/HOW-TO-READ-CIRCUIT-DIAGRAMS/" rel="nofollow">http://www.instructables.com/id/HOW-TO-READ-CIRCUI...</a></p><p>You can also follow the collections on the circuit board to see how things are connected.</p>
<p>What kind of potentiometer was used for this project? I'm new at this and I got it all working on the breadboard and am in the process of soldering, but the pontentiometer I have is gigantic- much too big to fit on the breadboard. If someone could give me a link or even a picture of what it should look like (it's a bit too small to see in the instructable) I think I'd be able to find it!</p>
<p>You can buy them at Radio Shack</p><p>http://www.radioshack.com/product/index.jsp?productId=2062301&amp;filterName=Type&amp;filterValue=Trimmers</p>
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?<br>Thanks for the simple!
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.
&quot;Thanks for the simple circuit!&quot; I meant to say.
<p>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.</p>
Love the idea, building one with a total of 20W of power LEDs. Might make an instructable about it, naturaly with credits to you ;)
Good luck. Let me know how it turns out.
Does your capacitor discharge itself in a day?
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.
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 &gt;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!
what size cap/pot would be required for a 5 meter LED strip
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. <br>I only get either highest brightness or very dim when I adjust the pot. Also, the LED's do not increase in brightness. <br>I am a beginner at electronics and thought this would be a good starter project. <br>Any assistance would be great. Thanks <br>
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. <br> <br>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. <br> <br>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.
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.
Could this be modified to operate a regular table lamp with, say, a 60 watt incandescent bulb or CFB? &nbsp;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. &nbsp;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.
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.
What voltage capacitor should be used?
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. <br><br>So for this project, you need capacitors that are at least 5V.
so good using as my science fair project!!!!!!!!!!!! <br>
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!

About This Instructable


547 favorites


Bio: My name is Jason Poel Smith I am a Community Manager here at Instructables. In my free time, I am an Inventor, Maker, Hacker, Tinker ... More »
More by DIY Hacks and How Tos: Giant Spider Web System For Automatically Limiting TV Time Remotely Control Your Halloween Props
Add instructable to: