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Thread: Pixel Relay: Simple Hack Provides "Pixel Control" to DC Powered Devices

  1. #1
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    Default Pixel Relay: Simple Hack Provides "Pixel Control" to DC Powered Devices

    I wanted my pixel sequence to control the DC power to a remotely located FM receiver/amplifier (it's in a ammo box hiding in the shrubs). And I wanted to use what I had in my stash of parts. The result is a cheap WS2811 controlled relay made from a 12V 5050 pixel segment and $2 relay module I purchased from AliExpress a couple years ago.

    Beyond my intended application, it can be used to control motor driven props, solenoids, dumb lights, and so on.

    This implementation is designed for 12V pixel strips/strings. Up to 3 relays could be controlled using the RGB assignments. I suggest keeping the switched (load side) voltage under 30V since IMHO the relay module's PCB layout is not a safe design for use with mains voltages.

    BTW, there's a number of ways to implement a pixel controlled relay. But I looked around the forum and didn't find a similar hack/project, so I will share what I did.

    Build Instructions: {See photos below for reference}

    Electrical assembly takes just a few minutes using basic soldering skills. Everything will easily fit in a PVC pipe enclosure. But I 3D printed a ABS plastic case for it. The transparent top cover allows me to see the RGB pixels; Blue turns on the relay. The other colors can be used to control more relays or act as system status lights. Or just ignore them.

    The parts list is short:
    - 1 each 12V WS2811 5050 Pixel (3 LED segment cut from spare strip).
    LED Example:
    - 1 each 12V Relay Module with Low Level Trigger input.
    Relay Example:

    A schematic is not necessary. The relay is a three wire connection: 12VDC, GND, and In Signal. Power connections are taken from the 12V WS2811 LED strip. The Relay's In Signal is connected to Pin-1 on the WS2811 IC. If you want to install three relays then use pins 1, 2, and 3 for the signal input on each relay.

    The relay module has a logic level jumper. It must be set to Logic Low. See photo below.

    This "pixel" relay is similar to a NULL pixel since it isn't used as a typical LED. But controlling the relay is the same as controlling a regular pixel. On my build the blue LED channel controls the Relay. Be aware that the RGB colors assigned to the WS2811 pins can vary on LED strips, so if in doubt just try each color or set it to white.

    - Thomas
    Attached Images Attached Images

  2. #2
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    Default Re: Pixel Relay: Simple Hack Provides "Pixel Control" to DC Powered Devices

    Here's the stl file set for the 3D printed enclosure. The end holes are for PG7 sized cable gland strain reliefs.

    - Thomas
    Attached Images Attached Images
    Attached Files Attached Files

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    Default Re: Pixel Relay: Simple Hack Provides "Pixel Control" to DC Powered Devices

    Great. Pixel Things (?) offers a board that has 9 ac channels of pix2ac, but it's $109.

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    Default Re: Pixel Relay: Simple Hack Provides "Pixel Control" to DC Powered Devices

    A product like the pix2ac is a close comparison to this DiY project. But theirs is for dimmable mains (110VAC) powered devices.

    This DiY pixel relay is intended for low voltage control applications. On/Off only, no dimming. Cost is about $2 a channel, so it's ideal for makers that have a tight holiday prop budget. Plus there's no limit to the relay count, just add more WS2811 segments with relays wired to their RGB pixel signals.

    I was thinking of using several pixel relays to create a bell ringing prop; Use big brass bells of various sizes and attach solenoids to strike them. Then create sequences that play Christmas songs. BTW, I have a commercially produced version for our indoor tree (purchased years ago, sounds terrific), but a supersized outdoor version would be fantastic.

    BTW, the relay boards are available in different layouts. Besides the single relay, there are versions with 2, 4, 8 and 16 relays. The only special requirement is that the chosen board must support low level pull-in. The one I used has a jumper to do this.

    - Thomas

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    Default Re: Pixel Relay: Simple Hack Provides "Pixel Control" to DC Powered Devices

    Yeah, if there was a design to easily map 3 pixel ic's to an 8-channel SSR board, that would help. I think I'll order some IC's on Ali and do that on the off season.

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    Default Re: Pixel Relay: Simple Hack Provides "Pixel Control" to DC Powered Devices

    Phil

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    Default Re: Pixel Relay: Simple Hack Provides "Pixel Control" to DC Powered Devices

    Thanks for posting the wiki info. The 5V WS2811 Bullet Pixel PCB shown in the wiki is available on AliExpress without the LED. I order a panel of 50 pcs a couple weeks ago for making 5V Pixel Relays and other hacks. Should arrive long after Santa makes his visit this year.

    - Thomas

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    Default Re: Pixel Relay: Simple Hack Provides "Pixel Control" to DC Powered Devices

    Quote Originally Posted by ThomasLED View Post
    Thanks for posting the wiki info. The 5V WS2811 Bullet Pixel PCB shown in the wiki is available on AliExpress without the LED. I order a panel of 50 pcs a couple weeks ago for making 5V Pixel Relays and other hacks. Should arrive long after Santa makes his visit this year.

    - Thomas
    Unless Santa is having problems with the China supply chain, too.

    The wiki is useful info. However, I don't see why you would want a long run length of 5V, unless maybe you want a not-quite-null pixel. It seems you would want your SSR's close, and run 120vac all the way. I also prefer to get those IC's on a small breadboard, but with those headers I don't know how to do that.

    Don't triacs run about 8 bucks apiece anyway? If you want dimming, maybe the pre-built board is right for that.

  9. #9
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    Default Re: Pixel Relay: Simple Hack Provides "Pixel Control" to DC Powered Devices

    Quote Originally Posted by ThomasLED View Post
    Thanks for posting the wiki info. The 5V WS2811 Bullet Pixel PCB shown in the wiki is available on AliExpress without the LED. I order a panel of 50 pcs a couple weeks ago for making 5V Pixel Relays and other hacks. Should arrive long after Santa makes his visit this year.

    - Thomas
    5V and 12v pixel pcb's are available . Using these for R,G or B channel/signal drivers was quite popular here a few years back .
    You can now use firmware that supports rgb which eliminates the need for these pcb's in most cases .

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    Default Re: Pixel Relay: Simple Hack Provides "Pixel Control" to DC Powered Devices

    Quote Originally Posted by angus40 View Post
    5V and 12v pixel pcb's are available . Using these for R,G or B channel/signal drivers was quite popular here a few years back .
    You can now use firmware that supports rgb which eliminates the need for these pcb's in most cases .
    How so? I want to control AC directly off my Kulp board.

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