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Paul Barnett
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Paul Barnett

Hardware Discussion  - 
 

I'm an winding up a LightShow Pi project, which I'll post in the next day or so. But, I just put up a string of LEDs on our house like these:

https://www.amazon.com/Sylvania-Christmas-3-function-Changing-Connectable/dp/B015QCU6UK

I currently have them configured to change continuously from white to color, then back. I didn't plan to use them with Lightshow Pi, but after watching it, I thought -- could I control them with Lightshow Pi?

There are only two wires connecting the string to the power supply, so, how does it separately power the two LEDs in each bulb? I suspected it was polarity.

I put a multi-meter on the power supply and let it cycle from color to white, and confirmed: It cycles from +12V to -12V and back. So, the bulbs must be wired so the white LED illuminates for one polarity, and color for the reverse polarity.

Since I can't turn on both lights at the same time, I'm not sure I could use Lightshow. But, does anyone see an potential opportunity that I'm missing? What kind of circuit would I need to control it?
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Brett Reinhard's profile photoPaul Barnett's profile photo
2 comments
 
Each light only has two colors: white and red/blue/green/yellow/orange Each bulb has white and one of the five colors. So, I can only illuminate the colored lights (at the same time), or the white lights (at the same time).

If the string is powered with +12 volts, it's in one mode. With -12 volts, it's in the other mode. So, I can only light one "mode" at a time. I will have to just pick one mode or the other, and assign that to a channel. However, I don't yet know if PWM would work.

I believe I can switch 12V from an ATX power supply using a MOSFET. Or, I could just get a SainSmart DC-DC SSR.

But, I was wondering if someone had a more creative idea.

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Paul Barnett

General Discussion  - 
 
Hey all, I think we should support this hardware in the next version of Lightshow Pi! :-)
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Paul Barnett

Hardware Discussion  - 
 
Has anyone tried these SSRs?

http://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Delectronics&field-keywords=hoymk+ssr

There are PCB style relays, and standalone relays with screw terminals.  

Depending on the model, the load can be DC, up to 65V and 25A.  Or, the load can be AC, up to 480V and 100A!  (no, that's not a typo).  There's even a 3 Phase version.

8 of them would be bigger than the SainSmart SSR:  at 62x45x26 (mm) each, vs. 138x71x25mm for the 8-channel.  But, I don't need 8 channels, and I'm considering a build that needs a 12VDC SSR + a 120VAC SSR.
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Tom Enos's profile photoIgor Kolesnik's profile photoPaul Barnett's profile photo
4 comments
 
That's actually how I found these relays:  I was looking for one to switch DC.  Most are DC-AC, but this one is DC-DC:

http://www.amazon.com/Hoymk-Ssr-10dd-Dc-dc-Actually-Single/dp/B00ORFSZXI/
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Paul Barnett

Lightshow Videos  - 
 
This is a proof-of-concept with a string of 10 RGB LEDs with a WS2801 chip in each.  I posted more details about the implementation in the Developer Discussion forum.

It's configured for 10 channels from 100-15,000 Hz, and each LED represents a channel.  The color changes from red to green to blue as the amplitude increases.

I used the obligatory Christmas light show music for a demo.  During certain parts, almost all of the lights are flickering blue, so this might not be the best example.  I'm going to dig through our music archives and look for a better choice. 
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Paul Barnett

Lightshow Videos  - 
 
It's a little early for Christmas lights, so I thought I'd show you what I'm doing for Halloween. The ghost is 15 feet tall. I removed the original white lights and replaced it with a string of 60 WS2801 lights. Currently, there are two channels, with every other light assigned to each channel.

I'm planning to do something similar with a 15-foot snowman for Christmas.
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Paul Barnett's profile photoDan Pallone's profile photo
3 comments
 
Sweet, I drove out for a snack and saw the origional of this, your's is much improved!!
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Paul Barnett

Developer Discussion  - 
 
+Tom Enos , I tried to install the master branch this afternoon, but ran into an issue in the installation of the rpi-audio-levels package:

cythoning src/rpi_audio.levels.pyx to src/rpi_audio_levels.c
Error compiling Cython file:
    float[:] data_memview = data
            ^ under the left bracket

src/audio_levels.pyx:46:18:Expected an identifier or literal

It subsequently fails during the gcc command, attempting to compile the bad source.

I simply renamed /home/pi/lightshowpi to lightshowpi-stable and did the download/install process again, except I didn't need to git checkout master.

My stable checkout still works, but I thought you'd want to know about the problems with the master branch.
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Paul Barnett's profile photoTom Enos's profile photo
10 comments
 
All better, I updated rpi-audio-levels.  If the version of Cython is < 0.19.1 it will install the latest version on pypi.
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Paul Barnett

Hardware Discussion  - 
 
After confirming that my proof-of-concept works (see my posts in Developer and Lightshow forums), I'm starting to give some thought to a hardware build.

In order to provide enough power to a relatively long strip of RGB LEDs, I'm planning to put a ATX power supply in a weatherproof (and vented) box, along with a Pi 2 B+.   The box will be placed at the start of the combined LED strip, but close enough to separately power every set of 50 LEDs.

As I put together a list of all the pieces I needed, I realized that adding a set of SSR's would be relatively inexpensive, and allow me to control AC  lights and complement my plans for the RGB LED strip(s). However, I'm a bit concerned by the builds I've seen.

I didn't expect full compliance with the electrical code.  But, I was surprised by the use of exposed bus bars, and no apparent fusing for switched AC circuits that will likely be outdoors.

I know the relays tend to act as a fuse, but I'd really like to avoid that kind of failure.  But, I haven't found a way to fuse the AC side of the relays at a reasonable cost (and size, since it all has to fit into the weatherproof box).   Has anyone found a solution?

Fusing the 5V side is easy:  I'm planning to use 5A automotive fuses for loads that should never exceed 3A.  But, that won't scale to 120V.
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Tom Enos's profile photoPaul Barnett's profile photo
7 comments
 
Yes, I'd like to help.  I have some ideas for preshow animations on the RGB LEDs, and I'd like to develop a plugin methodology for them.

I've also been experimenting with different light modulation techniques, like fading from red to green (Christmas colors) and red to white (candy cane colors that match existing Christmas lights on our house).  So, maybe we should consider a plugin methodology for that, too.

The flexibility of the RGB LEDs is giving me a lot of ideas, but I don't want the complexity to get out of control.   A plugin methodology could include a set of "pre-packaged" functions, but also allow code-slingers like me to write our own, without having to modify the base framework.

However, it will be a month or two before have any significant amount of hardware to test.
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Paul Barnett

Developer Discussion  - 
 
Looking through the postings, I don't think I've reinvented the wheel... yet.   But, I've modified update_lights() to use a small string of 10 RGB LEDs with WS2801 chips.   It's strictly a proof-of-concept:  I want to scale it up in time for the next holiday season.

I used BiblioPixel (from +Maniacal Labs) to drive the interface.  After modifying the configuration to think there are 10 GPIO pins, it simply treats each LED as a separate "channel".    An LED transitions from red to green to blue as the amplitude increases.   I posted a video in the Lightshow Videos forum if you want to see the result.

My question:  is there any practical limit to the number of "channels" on a Pi 2 B?  I think I can power up to 150 LEDs in one string with an appropriate power supply, and if I could divide the frequency range into that many "buckets", I think the result would be interesting.
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Paul Barnett's profile photoTom Enos's profile photo
7 comments
 
If you have the time give this a try.
https://bitbucket.org/tom_slick/lightshowpi/src/c800dbd3c42f5ed5db1012b7daf1de1072defd2a/?at=lightshowpi-led

After the sync files are generated I was able to get clean playback with 250 leds on a B+.
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