RGB LED Strip With Dimmers on RGB Lines and Colour Organ




Introduction: RGB LED Strip With Dimmers on RGB Lines and Colour Organ

About: I'm a mechanical and mechatronics engineer with a PhD in robotics. In my spare time I love playing soccer and tinkering with electronics!

I have previously put together a circuit very similar to this one which was comprised of a single colour LED strip which had a dimmer on one circuit and an 'audio pulsing' circuit on the other... The Instructable can be found here: https://www.instructables.com/id/LED-Strip-Control-...

After I uploaded this Instructable, I received many requests to do a version of this circuit with an RGB LED strip instead, so here it is! Hope you all enjoy this Instructable as much as the other one!

This Instructable will walk you through how to make two circuits: one which, when powered on via the SPDT switch will be a dimmer on each of the RGB lines (I also recently just posted this as a separate Instructable: https://www.instructables.com/id/RGB-LED-Strip-Dimmer-With-555-Timer/), so you can create any mix of colours manually with a few knobs. The other circuit is a Colour Organ which will pulse the RGB lines with a given frequency band of an audio signal which is fed into it. The colour organ design is taken from https://www.instructables.com/id/RGB-LED-STRIP-COLO..., I really like this design and I have made the circuit before for another project, so I know it works well!

To merge the two circuits takes a bit of work, so, let's get to it...

Step 1: Gather Your Materials

You'll need a bunch of parts for this build...

Electrical Components:

1 * NE555

1 * NE556 Dual 555 timer linear IC

3 * TIP31 transistor

6 * 100nF capacitor

3 * 1N4007 diode (not really required, but included due to prototyping laziness and circuit changes)

2 * 1N5404 diode

7 * 1N4148 diode

3 * 10k variable resistor https://www.jaycar.com.au/10k-ohm-linear-b-single-...

1 * variable resistor knob (red) https://www.jaycar.com.au/red-push-on-style-knob/p...

1 * variable resistor knob (green) https://www.jaycar.com.au/green-push-on-style-knob...

1 * variable resistor knob (blue) https://www.jaycar.com.au/blue-push-on-style-knob/...

5 * 4.7k resistors

2 * 100R resistors

1 * 10uF capacitor

2 * 20k resistors

1 * 2N3904 transistor

3 * 2N3906 transistor

1 * 47nF capacitor

1 * 1k resistor

3 * 2.2k resistors

1 * 150R resistor

2 * 270R resistor

1 * Red LED

1 * Green LED

1 * Blue LED

3 * 11N60C3 N-type MOSFET

1 * 0.47uF capacitor

1 * 0.01uF capacitor

1 * 1uF capacitor

1 * SPDT switch https://www.jaycar.com.au/spdt-centre-off-rocker-s...

1 * 2.5mm power connector

2 * AUX connectors https://www.jaycar.com.au/3-5mm-stereo-chassis-soc...

1 * suitable enclosure

1 * RGB LED Strip of your chosen length. Here's what I bought (5m): http://www.ebay.com.au/itm/5050-SMD-RGB-5M-150-300...

1 * 12V 6A power supply to go with the LED Strip

Various sizes of JST connectors http://core-electronics.com.au/jst-connector-kit-2...

A bunch of wire


Electrical tape





Soldering iron

Side cutters



Sand paper

Bench top vice

Hobby knife

Step 2: Prepare the Enclosure

In this step you will prepare the enclosure for mounting the interfacing components. This involves drilling out the holes for the potentiometers, aux connectors and power connector. Also, you will need to drill a small hole which you will feed the LED strip wires through. For the power switch, I recommend drilling some small holes, then if you're working with plastic, take the soldering iron to it to get the right shape that will fit your switch. Clean it up with a hobby knife- the melted plastic should peel off easy. Mine looks a little rough around the edges, but the switch covers it anyway.

Step 3: Prepare the Parts That Attach to the Enclosure

In this step you'll be soldering wires to the following and putting JST connectors on the ends:
AUX connectors: 3 pin JST to L & R audio and GND.
Power connector and SPDT switch: 3 pin JST. The JST will have a ground which comes from the power connector and two power lines from the SPDT Switch. The V+ from the power connector goes into the SPDT switch directly.
Potentiometers: 3 pin JST.

Depending on the thickness of your enclosure and the shaft length of your potentiometers, you may also have to take the hacksaw and cut down the shaft of the potentiometers. You should also sand down the shaft once cut, just to make sure it has nice smooth edges that the cap can easily slide onto.

Step 4: Fit the Parts You Just Prepared Into the Enclosure

Put the parts you just prepared in their places!

The AUX connectors are easy, they just screw in with a nut.

The switch should click in place if you sized your hole correctly.

You should also be able to screw in the potentiometers and top them off with their caps. I went with the order of RGB, but you can place these in any order you like, so long as they match up with the correct colour in the circuitry!

Step 5: Solder Up the Veroboard

Take the attached circuit diagram as a reference and carefully plan out the positioning of your parts. I used quite wide boards so I could maximise the space by cutting tracks where I had to, especially where I've placed the three TIP31C transistors, MOSFETs and other transistors. Be smart about your placement of components if you're really pressed for space (think about the size of your enclosure you need to fit everything into!). Then take your time to systematically go through and make sure you have all of the components. Next, get to soldering! I soldered the two circuits on separate boards and just had a power cable running from one to the other. Remember to leave space for your JST connectors which will interface with all the components you just fitted to the enclosure. I ran out of space in my enclosure to mount a 3 pin JST to go from the MOSFETs of the audio pulsing circuit to the LED strip so I have soldered some wires directly to the board instead which terminate in a JST on the other end (as shown in the pictures). I also had to clip the top edges of each bit of veroboard for them to fit in the enclosure properly.

Step 6: Secure the External Connectors to the Enclosure

With all of the parts now in place, you'll need to secure the external connectors to the enclosure. I had some extra sugru lying around that was about past it's use by date so I opted to use that, but hot glue would also suffice. The aux connectors shouldn't need any securing as they screw on with the provided nut, but I had leftover sugru so I used it for extra security on the inside of the enclosure.

The power connector will need something to keep it in place; I position mine by connecting the barrel connector to the power supply and then apply some sugru. I left the sugru to cure overnight and then removed the power supply and the connector is then perfectly positioned and ready to go!

Finally, the wires leading to the led strip connector need to be fed through the hole in the enclosure. I left generous lengths of wire inside the enclosure and applied some sugru on both the inside and outside walls of the enclosure around the hole to hold the wires in place.

Step 7: Plug Everything in and Test

Plug in all your components via the JST connectors and plug in the power to test it all works!

One circuit should be for the dimmer, so check that you have control over the red, green and blue lines of the LED strip individually, then you can have some fun mixing the colours. Check out the attached video which shows me testing my dimmer circuit.

The other circuit will require you to plug in an audio source. Plug in the aux cable to go to your audio source and plug in the speakers on the aux out connector, turn the volume on your device up to maximum and see the lights dance!

Once you're happy that it all works, find a nice place to set up your LED strip (I haven't found a good spot just yet...). Then you can enjoy your cool little LED control box!

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    4 years ago

    Cool project. Kudos!

    I noticed that the schematic in the attached ZIP file is different from the one you have included in this instructable. (The one included in this instructable simply wont work).
    The one in the ZIP file will work sort of.

    1. There is an erroneous connection connecting C7, R9, R10 & D12. This has the effect of shorting R10 and passing the audio signal to ground via D12.

    2. D10 & D11 serve no purpose. Just wire LED1R, LED1G & LED1B anodes to +12V.

    3. Transistors are current devices. The base on the NPN draws current and should be limited by a resistor. D14, D13 & D2 should be replaced with a resistor to limit the base.

    4. MOSFETs are voltage devices so theoretically the gate shouldn't draw or sink current. However MOSFETs aren't perfect. A 10K resistor in series with the gate wouldn't hurt.

    Keep up the good work :-)


    Reply 4 years ago

    Thanks for your comment. I'm a bit swamped with work at the moment so I'd really like to have a thorough look through the points you raised and fix up the instructable sometime soon!


    5 years ago

    Very nice construction technique an excellent Instructable !