Tri-LED Color Mixer





Introduction: Tri-LED Color Mixer

This project uses three 555 timers to create a PWM to control the brightness of 3 LEDs pairs. Three different color LEDs are used as well as a tri-color LED to show the mixing the colors. Each color has it own 555 PWM circuit and potentiometer to control it. It runs on a 9 volt battery. Tri-color LED in encased in an old flashlight lense.

Step 1: Step 1. Schematic and LTspice Simulation

Entered and Tested circuit in LTspice first. I found this useful and made several correction in this step.

Attached is the LTspice schematic and LTspice *.asc file

Step 2: Step 2. Built 1/3 of the Circuit on a Breadboard

I built the circuit (1/3 of it , only one color) to test it out and decide on the parts layout.

The circuit worked as in the LTspice simulation, but the LED switched Off/On too quickly and I wanted to use more of the Potentiometer to control the LED. So I added a 800 ohm resistor across one side of the Potentiometer. This did help.

I than rearranged the layout so it would fit within 10 rows of the breadboard. I did this so 3 of the circuits would fit on a Adafruit Perma-Proto Half-sized Breadboard PCB.

Step 3: Step 3. Add Parts to Adafruit Perma-Proto PCB

I then started soldering. I added all 3 LED circuits to the Adafruit Perma-Proto Half-sized Breadboard PCB.

Picture shows completed PCD and wires coming in from PS and front panel.

Step 4: Step 4. Drill/Wire/Build the Panel

I than added the potentiometers/LED/Old flashlight and 9 Volt connector to a ABS Plastic Bud box.

I made sure wires are long enough to allow a little movement in and out of the box.

Step 5: Completed Project

Here is a picture of the completed project.

I think my grandkids will like playing with it!

Parts list

  1. Enclosure. Bud Industries, part #: CU-1874-B. $3.00
  2. Potentiometer 10K. TT Electronics/BI, part # P160KNP-0QC20B10K. 3X $0.76 = $2.28
  3. Knobs. SparkFun Electronics, part # COM-11951. 3x $0.95 = $2.85
  4. Perma-Proto Half-sized Breadboard PCB. Adafruit, part # 1609. $ 4.50
  5. Stand offs. Keystone Electronics, part # 2211. 4x$0.47= $1.88
  6. capacitor, 3.9nF, 100V. TDK Corporation, Part # FG28C0G1H392JNT06. 3x$0.32 = $0.
  7. capacitor, 1µF, 16V. KEMET, Part #C330C105K5R5TA. 3x$0.47 = $1.41
  8. diodes. OnSemi, part # 1N4149. 6x$0.08 = $0.48
  9. bipolar transistors. OnSemi, part # KSP2222ABU. 3x$0.18 = $0.53
  10. NE555s. Texas Instruments, part # NA555P. 3x$0.37 = $1.10
  11. 9 volt battery connector. Keystone Electronics, part # 968. $1.15
  12. RGB LED 10 mm. SparkFun Electronics, part # COM-11120. $0.95
  13. Red 5 mm LEDs. Kingbright, part # 754-2139-ND. 2x $0.67 = $1.34
  14. Blue 5 mm LED. Kingbright, part # 754-1919-ND. $0.56
  15. Green 5 mm LED. Kingbright, part # 754-2018-ND. $0.75
  16. Resistors. Several misc resistors
  17. Old AA Flashlight. Cut and only use the lense.

Total Cost $23.74



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    I too like the transistor & basic components. I was wanting to know how the 10K potentiometers connect into the schematic circuit. Does it replace the two stacked resistors with the "out" from the 555 in the middle? Thanks!

    1 reply

    "Does it replace the two stacked resistors with the "out" from the 555 in the middle?"

    Yes, this schematic is from LTspice. LTspice does not have a good Potentiometer simulation (at least I could not find one). So the 2 resistors (R2 and R3) are my way to simulate a Pot. In simulation, I would change ratio R2/R3 to for example: 1K/9K to simulate that point of the POT position. Than set them to 9K/1K to simulate another point in the POT. Than I would run LTspice and see the width of the pulse coming out of the 555 circuit.

    Nice electronics tutorial. Microcontrollers are cool. But it is nice to see a project that uses old school electronics components.

    1 reply

    Yes, I started with an Arduino design that had 3 Pots as inputs and PWM output to the LEDs. I showed this to my 5 year old grandson and he loved it! So I wanted to make something for him that performed the same function, that didnt use my Arduino. This is what I came up with.

    Very clever idea and great implementation, without software! I may borrow your design for any future project that needs a simple, cheap PWM.