Touch Sensitive RGB LED Mood Light





Introduction: Touch Sensitive RGB LED Mood Light

LED Contest

Runner Up in the
LED Contest

I always really wanted a cool LED Mood Light, but all of them I have seen on Instructables use IC's, and I find IC's take out some of the fun of building circuits. That is the reason I designed this lamp. I also wanted to make sure all the parts were available from Radioshack, because I know there are other people, like me, that don't or can't order off the internet, which is another reason IC's are no good for some people. Radioshack doesn't carry a great selection.

*As well, as a bonus, since this is power by 5-6v dc it can be USB powered, but I power mine from either a 6v dc 300 ma wall adapter or 4 AA batteries.*

Step 1: Parts, Tools and Materials

This isn't an overly difficult circuit, but may be a little difficult for a beginner, but with slow and careful work, anyone can build this.  If you are a bit of a beginner, the Optional Markers under tools should come in very handy, as well as the color coated wire under materials.  For markers, I find the Colors, Black, Red, Green, Blue and Orange were of greatest help.  They are good for marking were leads of parts go onto the Perfboard and allows you to figure out what configuration will work best for you.  Just make sure you remember your color code!  As well, a solderless board is also a good idea.

For tools:

- Wire strippers
- Solder and Soldering Iron
- Glue gun (For gluing long leads down so the wire doesn't bend back and fourth and 
- Dremel or Tin Snips (Anything for cutting Perf Board)
- Side cutters
- Markers (Optional)

For Parts:

- 3x 2N3906 Transistors (Or similar)
- 3x 2N3904 Transistors (Or similar)
- 3x 1000 uF 6.3+volts capacitors
- 3x 6 ohm 1/4 watt resistors (Color code, Blue, Black, Gold, Gold)
- 3x 10k ohm 1/4 watt resistors (Color code, Brown, Black, Yellow, Gold)
- 1x 330 ohm 1/2 watt resistor (Color code, Brown, Black, Brown, Gold)
- 3x 1N914 Diodes
- 3x Germanium Diodes
- 3x Red LED
- 3x Green LED
- 3x Blue LED
- Momentary Push Button Switch
- DC Barrel Jack or Battery pack
- On/Off switch (Optional)
- Ribbon Cable with Plug (Optional)
- 5-6v dc power supply.  I used 4 AA batteries.

For Materials:

- A lamp or other enclosure (Not covered yet, as I want to enter this in a Contest, will be 
  updated later)
- A shade or something to blend colors (In the video I used a Paper Funnel)
- Assortment of wire, preferably color coated

Step 2: Circuit

The circuit diagram is provided in the picture below.

The LEDs aren't shown in the second diagram because there are two configuration you can use.  I wired them in Parallel because I believed that the voltage drop across them would make them too dim.  However, it is your choice to put them in Series or Parallel.  In Series, all the LEDs will be the same brightness but may be somewhat dim.  In Parallel, due to small differences in each LED, they may be slightly different brightnesses, but will be brighter overall then the series.  This is something to think about, the circuit should work both ways, so it is completely up to you how you wire your LEDs.

As well the LEDs are setup in this fashion:

Red Green Blue
Blue Red Green
Green Blue Red

Step 3: How It Works

I wanted people to be able to build this circuit, but also understand its workings, if they didn't already understand it.  Anyone can build a circuit, but I wanted to make sure people knew how it worked.

This is a very simple circuit.  In the pictures you can see one piece of the circuit.  It is one controller for one color.  They all work exactly the same though.

When a finger is placed across positive and one of the three pads, it turns on the corresponding NPN transistor.  This allows power to flow to the rest of the circuit.  The ability of a capacitor in series with a resistor to increase the time it takes to charge allows the LED to come on slowly, allowing you to vary the brightness based on the length of time you leave your finger on the touch pad.  Then the very large resistor after the capacitor slows its discharge so that the lamp doesn't immediately dim.  I don't know how long it will stay lit for, I think somewhere between 5 mins and 30 mins.

To turn it off, the momentary switch is pressed for about a second which discharges the capacitors.  The Germanium Diodes are needed so that all the capacitors don't charge at the same time, which wouldn't allow you to vary each color.  The Germanium Diodes are only good for small current, but will take a substantially high Surge Current, and since the capacitors discharge immediately and no more power flows, they are acceptable for use here.

If you wanted to increase the power supply and add more LEDs, you would have to change values of certain components accordingly.

Step 4: Construction

Start with the Transistors, all of them.  Careful of which direction they go and don't get NPNs mixed up with PNPs.  Tack them on.  Next do the Resistors and 1N914 Diodes.  Next solder the positive jumpers and negative jumpers.  Next solder the 3 capacitors on.  Careful of capacitor polarity.  Finally solder the 330 ohm 1/2 watt resistor and the connections for power (2, + and -), Touch Sensors (4, R, G, B and positive),  LEDs (4, R, G, B and return to 330 ohm resistor), and for the off button (4, one off each negative lead of the capacitors and the last to positive.  The three from each capacitor need to be cut in half and add the Germanium diode, careful of polarity, into each wire before connecting all three together then to one side of the momentary switch.  The positive lead attaches to the other side of the switch.  If this is confusing look at the last picture)

For the LEDs, Figure out what configuration works best.  I found one hole between everything worked best and was easier to solder.  Tack one leg at a time.  Make sure they are all lined up the same way.  This is the hardest part because the optimum configuration has same color LEDs scattered around the board.  GO SLOW!  Use color coded jumpers on the bottom.

Step 5: Test and Enclosure

Now that you have everything soldered, test it.  Carefully check and connect negative and positive.  Find the touch return and press one finger to it then one of the colors.  The LEDs will take a few seconds to get enough power to be visible.  Once they turn on, try all 3, then try the off button.  If it doesn't work, disconnect power, and check wiring.

If it works, Congratulations!  But your not quite done yet.  You should put it in a case.  A lamp that would be good for mounting the touch sensors and off button would work.  If you wanted, a plastic box would work if you put everything in it and ran the LEDs up on top with a CD holder (The tall clear ones)  that had some Mat White paint on the inside of it.  Anything clear doesn't work because you can see the colors individually, but by using a translucent material (I used the paper funnel) the colors blend and trick your eyes into to believing the lamp produces any color.  

I will update this part later when I have mine in a case.  Due to time constraints, I want to get this entered into a contest first, then I can add in the enclosure section after as I want to find a really nice lamp to put this in and I don't know when I will find THE PERFECT LAMP!  However, the enclosure is up to you!

If anyone makes one of these, I would love to see pictures of it, so post them in the Comment Section below!  :D



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    I am curious about how the all touching thing works.Are there switches of sorts? Or you just tap the wires with your hands to make the color switch?

    The way it works is there are 3 NPN transistors, one for each color. NPN transistors work that when the voltage at the base becomes positive they turn on, and power can flow across the collector and emitter. The base voltage can be very small and it can control a large amount of power across the collector and emitter. Since you don't need a large voltage we use skin resistance to control when they are on and off. So there are 3 leads, one from the base of each transistor, and each have a small gap between it and the fourth lead, and the fourth lead goes to the positive terminal on the battery. That way when a finger is placed across the gap of one or more of the gaps it turns one or more of the transistors on. The longer a finger is held across the gap, the brighter the lights get.

    I see now, thanks a lot!

    Plus, I could not find germanium diodes so I consulted my electronics teacher at the university and he told me to switch them with pyritium diodes. Do you think it would make any difference?

    Pyritium? O_o Wow, uhhh, I use whatever I can pull for stuff at the dump and in a over-priced store with very, VERY poor selection, so I have never heard of Pyritium Diodes. I would say they should work. I used Germanium diodes because they have lower voltage drop then standard rectifying diodes (1N4001 or similar) so if Pyritium possesses the same low voltage drop quality as Germanium I would say it should work. In all honesty, even standard rectifiers like the 1N4001 should work. It might affect it, but it probably wouldn't even be noticeable *IF* it did affect it even. If your Uni Teacher suggested pyritium, then he is probably right, I am self-taught and have about 3 years experience, he probably has alot more then that. If you showed him my schematic, he could probably make alot of improvements/changes...That's kinda of a cool thought actually, getting someone with alot more experience to look at it. I would find that very educational. Sorry, I am getting off topic.

    To answer your question, yes, they should work with little to no noticeable affect.

    I will show him :) He is so crazy that he may add a fridge or a laser gun on it as a bonus. :) Will post here his comments.

    Thanks! I think this could be a good learning experience!

    Also, he sounds like an...interesting...fellow. Maybe not someone you would want around said laser gun, but inertesting none the less! :P I have heard that Uni Teachers have a tendency for being kinda out there though! Haha!

    Can wait for a reply! Thank you!

    nice work, very great project

    Looking at possible selling these as a kit, if anyone would be interested message me. Price would be set about $30 - $35, maybe $25 if I can find cheaper, but still very bright LEDs. Mind you, I don't have any yet, I just want to see if this would be worth while.


    does it really sense the mood of a person?

    Not really, its more like a touch sensitive dimmer switch for each color and you adjust it to the color you want. Now that I think about it, this is probably more accurate then any temperature sensitive mood light, just because subconsciously a person will probably adjust the light to a color that they at that moment will enjoy and this is probably affected by emotion, so it can be argued to be a mood lamp. But it doesn't matter too much, I called it a mood lamp cause you can make any variety of colors (Except black, grey or brown) which is all a mood lamp does...