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, 1ĀµF, 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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    4 years ago

    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!


    Reply 4 years ago

    "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.

    DIY Hacks and How Tos

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


    Reply 4 years ago

    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.


    4 years ago

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