How to Blend Colors With LEDs
Light-Emitting Diodes (LEDs) are low-power, high-intensity, and extremely resilient electrical components. They produce virtually no heat, and almost all the power usage goes toward the production of photons instead of heating the light element within. They have no moving parts, no "burning" filaments, and can be microscopically tiny. It's really no wonder why LED displays are becoming so popular. Since their function is to produce light, you need only three colors of LED in order to produce the entire visible band of the electromagnetic spectrum. Light is additive, meaning every color can be produced by a combination of red, green, and blue.
Other People Are Reading
Things You'll Need
- 1 high-intensity red LED (with leads)
- 1 high-intensity blue LED (with leads)
- 1 high-intensity green LED (with leads)
- 1 diffuser lens
- 3 rheostats (with leads)
- 1 9V battery
- 1 roll electrical tape (optional)
- 1 soldering gun with solder (optional)
- 1 pair electrical gloves
Instructions
-
-
1
Connect the low-potential lead of each LED to the negative terminal of the battery using either a soldering gun and solder or by simply wrapping some vinyl electrical tape around the connection (use black, UL-approved electrical tape, if you want to adhere to international standards). You don't need the connection to be permanent (unless you want it to be); you really need only a good electrical connection for this experiment.
-
2
Connect the high-potential lead of each LED to one terminal on a respective rheostat. By inserting rheostats into the circuits, you are introducing variable resistors, which allow you to selectively tweak the amount of current flowing through each LED. As you increase the resistance of a rheostat, you decrease the current flowing through the LED and decrease its intensity.
-
-
3
Adjust the rheostats so that they are at maximum resistance. This ensures that very little current, if any, will flow as soon as you connect the battery in the next step. Be sure you are wearing your electrical gloves at this point, if you aren't already wearing them.
-
4
Connect the remaining leads from the rheostats to the battery. If soldering the connections, be careful when connecting the battery, as the battery terminals can be easily damaged from the heat of a soldering gun. Fortunately, with a single 9V battery, you'll likely be left unharmed (although, perhaps in some minor pain), should you make a mistake and shock yourself.
-
5
Place the diffuser lens between the LEDs and your eyes (the lens can be anything that diffuses light; amusingly, a "soft" incandescent light bulb works wonderfully for this). The diffuser lens will scatter the light passing through it so that you do not see the light from three individual LEDs, but rather one "fuzzy" light made of the combined light from all three LEDs.
-
6
Adjust the rheostats individually to increase or decrease the brightness of their respective LED. By changing the intensity of just one rheostat, even slightly, you will produce a new shade of color, as seen through the diffuser lens. Increasing the resistance of two of the rheostats completely will give you pure red, green, or blue light (depending on the rheostat you left at low resistance), and setting all rheostats to an equally low resistance will result in white light (which is, incidentally, sunlight).
-
1
Tips & Warnings
Unless you are building a permanent circuit for use in a larger application, secure the connections with electrical tape. Soldering is difficult and messy to undo.
If you want to produce various colors at a high brightness, you will want to use banks of LEDs grouped in RGB (red, green, blue) trios.
Neglecting to maximize the resistance of the rheostats before connecting them to the battery will likely result in a complete discharge of the battery (9V batteries have a fairly low capacity). You might also get a painful shock as it discharges through your fingers.
References
Resources
- Photo Credit led image by sasha from Fotolia.com
