Introduction: Touch Sensitive RGB LED Mood Light
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.
- 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)
- 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.
- A lamp or other enclosure (Not covered yet, as I want to enter this in a Contest, will be
- 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