# LED office-desk lighting system

#### kdaffolder

Joined Aug 2, 2009
1
Hi, I am a newbie to electronics, and am in need of some help with making a schematic for a hobby project. As the title states, I am wanting to make a LED light system for my home office desk. Below are the requirements that I would like this LED light circuit to implement:

I am planning on mounting these LED strip-lights to the bottom of a shelf, to light the desk. One strip will be white, the second strip will be blue, and the third strip will be green. The LED strips will be exactly 5 ft. long. Please click here to view the LED strip lights I am wanting to use (unless there's something better.)

LED light system main control desktop unit (hopefully small enough to house in a plastic electronics box and affix to the desk):
I need to have a way of selecting which color series of LEDs I would like to light up at any given time...so, Im thinking some type of metal contact touch-sensitive button/circuit for each color (ie. when the metal contact/button for green is touched, all 6 of the green LEDs light up, and the two other colors do notwhen white is touched, the white LEDs turn on and are added to the mix. If possible, I would like to be able to have some type of a touch-sensitive contact, button, or circuit (maybe metal?) so that I could control the off & on of each color, that way I can add/subtract colors together, etc. Also, I would like each of the three colors to have a slider or rotary dial/variable resistor that I can use to dim their corresponding color. (ie. when I move the slider connected to the white LED strip, the white LEDs brightness changes so that I can dim or increase their brightness.) Touch-sensitive buttons are of course optional, but would be preferred. I would of course settle for a typical push-button.

Also on the light systems main control, there needs to be one other button; Off. I need to be able to have the functionality to turn power to the entire circuit off at any given time. So, the off button would simply turn-off any of the LED light strips that had been turned on.

Remote control for lighting system (OPTIONAL!):
If even possible, and it would not be too terribly hard to do, I would like to try and construct a wireless remote that could send commands either via infrared, radio frequency, etc. to the light system so that I could control its functions elsewhere in the room remotely. It would need to be able to control the same functions as the main lighting control unit. So, something much like a TV remote is what I would like to build and be able to remotely control the LED lighting system. Again, this is optional, but it would be really cool to have a this functionality.

Phototransistors/Photoresistors/etc:
I would like to place two phototransistors, photoresistors, photothyristors, etc. into the top shelf of the desk so that when it gets darker in the room or the room lights are turned off, then these light sensing units would trigger the circuit to turn on, by default, the blue LED lights. I am suggesting two separate sensors so that they both would have to be dark for the LEDs to kick on (ie. less prone to being activated by a shadow on one of them, etc.) There would need to be a switch on the main control desktop unit so that I could either enable or disable this light-sensing feature. (As you might guess, it would be a nuisance for a shadow to fall on the light sensor and kick the lights on, when the room is well-lit and there is complete daylight. It might also be smart to wire in some type of delay so once the light sensors recognize the light is missing, they would wait shortly before kicking on the blue LEDsthat way if a shadow fell on one sensor shortly and did not stay, then the LEDs would not kick on.please note, this delay feature would be optional.

Power:
Lastly, the entire circuit or set of circuits needs to be powered by a cheap AC wall adapter. So, it might be a challenge to get the LEDs to work with an AC current without flickering on and off (because of the alternating current), but thats what Im aiming forI do not wish to keep purchasing and replacing batteries. I am in the US, so the AC adapter would need to be rated for US wall outlet standards. I'm thinking something simple like an AC-DC wall adapter or so?

So, my mission is to construct a circuit that of which fulfills all of the requirements and ideas I have listed above. I decided to post to this forum as it was quite frequent in Google searches, everyone seemed friendly, and knowledgeable. I am hoping to receive any help that I can get, as I am not real familiar with electronics. I can solder, but when it comes to planning and making schematics, that is not my forté. I would love to learn how to design this project's circuits, but I am not sure where to get started. I am hoping that someone could maybe mentor me and walk me through the process.

I cannot envision this project taking too long to complete, but I am hoping that some people would find this project as interesting a challenge as I do, and be willing to help me spear-head the project and come up with a solution. Below are some pictures of the desk as well as some research I did on circuits like this:
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Here are 3D renderings of the desk I own:

(Desk without LED lighting system)

(Desk with LED lighting system. LEDs are affixed to the underside of the shelf. Notice how the LED system shines down on the main surface of the desk.)

(LEDs are affixed to the bottom side of the shelf as pictured above. They shine down on the main surface of the desk as pictured in the above photo.)

(Sample construction of what features Im wanting the remote to have. Notice the White, Blue, and Green touch-sensitive buttons/switches that turn on their corresponding colors when touched. Also notice the Sensor On/Off touch-sensitive button/switch which controls whether the 2 photoresistors/phototransistors are turned on or are over-ridden and turned off. There is also a manual touch-sensitive Off button/switch which will kill power to the entire lighting system at any given time. Lastly, please notice the 3 separate faders/sliders/dimmers/variable resistors which control the dimness/brightness of each of their corresponding colors, and then a master fader on the bottom which controls all of the colors at once.)
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LEDs:

These are the LED model specs that I am planning to use. (Mouser Product # is included:

Blue LED strip-
Mouser Product #: 828-OVQ12S30B7
Manufacturer: OPTEK
Part #: OVQ12S30B7
Description: High Power LEDs Blue, 470nm Flexible Strip
Price: $12.09 per 19.7 inches Green LED strip- Mouser Product #: 828-OVQ12S30G7 Manufacturer: OPTEK Part #: OVQ12S30G7 Description: High Power LEDs Green, 525nm Flexible Strip Price:$12.78 per 19.7 inches

White LED strip-
Mouser Product #: 828-OVQ12S30WW7
Manufacturer: OPTEK
Part #: OVQ12S30WW7
Description: High Power LEDs Warm White, 3300K Flexible Strip
Price: \$13.49 per 19.7 inches

If these will not work, I would like to find something else then on either the Mouser or Jameco websites. Just make sure that if you other LEDs are used, that they are high-output LEDs that are really bright and also have a good spread. I would prefer that they be similar to the ones listed above.

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Please see the attached PDF file to this post if you are knowledgeable and interested in helping me figure out this circuit. It contains some research I have done on schematics that might work-in-part for this LED lighting system. I would appreciate any insight, and all help with this project is welcome!

Thank you all!

Sincerely,
Kyle

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#### jj_alukkas

Joined Jan 8, 2009
753
Phew! ,that was one long wish list. This is a simple project but making each feature for 3 channels is a headache. Can be done quickly if you get the ideas, but each feature you asked for will make everything bigger and complex and will need more time to accomplish.

For your first question, if its simply on off, you can use ordinary SPDT switches for each strip. For micro switches, you could use a relay per strip and even replace that micro switch with a bubble switch ( ones used inside mobile phone keypads). Dont know if these are commercially available but it will make the keypad flat like touch. You can go for pure finger resistance touch with a darlington pair transistors with that relay I suggested previousely. So that decides your first part - whether you need a single switch or a whole circuit for simply ON/OFF. Decision left to you.

Then for brightness controll, use PWM circuits with IC's like 555. For individual control, you will need one circuit per strip and you can use sliders or rotary potentiometers. Connect this circuit after the power control circuit.

Also add a master touch or 3 pole button for complete shutdown.

Remote control is possible but only one or two commands is easy to implement for a begginner using electronics. If you need more commands, you need to go for a dedicated chip like the ones used in TV's. I have no Idea abt those IC's. And the 2nd way is to settle for a microcontroller which can do what all you asked and more using a single uC. But it is quite hard to implement without the programming skills. Can try if you have the time and knowledge source.

Light triggered switch on is fairly easy, but to use 2 LDR's or phototransistors makes more of a mess. One phototransistor would do quite well if you use a delay with it which most circuits feature. If its individual control you ask for, then you will have to make 3 of these and either override the power buttons or wire it b\n the power control and brightness control boards. Make one which has a delay as its easy to implement.

Power supply could be from a AC SMPS adapter. But first decide the circuits and IC's to be used and calculate the voltage required before you jump to buy one. You could also use a transformer, rectifier and filter with regulator, but the overall build size would be larger and costlier that a cheap SMPS.

These are the ideas. You can google for the circuits I described and put it together. If you have any doubts, feel free to ask and we will help you for modifications or problems. A single microcontroller and 3 MOSFETS can do it cheaper, simply and easily. If you have a friend who can help you with programming, it would be easier. If you need to learn, do try it this way. Now its time for your homework.