Point Source Pixel – First Run
Posted by JEC on December 2nd, 2008
Point Source pixel. Based on the original RGB design but with a 10mm RGB LED.
I’m really happy with this design. Adding some 1″ clear heat shrink tubing will make the design waterproof and safe to use outside. Of course, it’s meant to be driven by a DMX Offset Machine, described elsewhere on this site.
The YouTube clip below is characteristsicly choppy, but in real life the colors are crisp and clear. The transitions are very smooth and the white light ‘strobe’ effect is very convincing.
To get a decent video exposure, I placed a 100W desk lamp directly above the pixel while shooting. This way, there was a reasonable balance between the LED light and the ambient light.
All current used by this device comes through the 78L05 regulator, making the system much less sensitive to voltage drops in the cable. Power supply of 7-12V DC, 70 mA per pixel, will work wonderfully.
The LED throws a neat shadow 10′ across the workshop onto the opposite wall.
Buy bare circuit boards for $3 each if you’re interested.
3/28/08 Further ExperimentationI chained 8 of the pixels together, just to see what would happen.
Wiring is more arduous than soldering the components in place! Each pixel has two sets of terminals in parallel with each other. This makes daisy chaining relatively simple.
I used 22 gauge shielded cable with 5 conductors: DMX ground, D+, D-, Pixel Power, Pixel Ground. Wires connected to the top and bottom of the circuit board. Then, the board lays flat.
Finally, I put a piece of 3/4″ clear heat shrink tube over the entire assembly. A small hole was punched in the center to let the LED peek through.
The ends aren’t completely sealed, but adding a few small pieces of 3/8″ heat shrink would close them up nicely. Waterproofiness is very desirable.
Coming soon: Video clips & photos of the chain in action.
Bill of Materials:
- C1 .1 uF 10v 0805 ceramic
- C4 10 uF 25v 0805 ceramic
- C5 1 uf 10v 0805 ceramic
- JP1 5 pin .1″ header, or leave blank
- JP2 5 pin .1″ header, or leave blank
- LED RGB LED, 4 pin, common cathode
- PGM 5 pin .1″ programming header, optional
- R1 80 0805 package
- R2 80 0805 package
- R4 1000 0805 package
- U$1 78L05 SOT-89 package
- U1 PIC 16F688 SOIC-14 package
- U2 MAX485/SN75176 RS485 transceiver, SOIC-8 package
March 22nd, 2011 at 2:43 pm
[...] by Matthew on Mar.22, 2011, under AVRs, DMX, Light Controllers Back in 2007 I stumbled across a house decoration that had fading RGB lanterns high lighting a path to the front porch. John Chapman of Engineering Solutions Inc Developed a suite id LED Based RGB Pixel projects/products. the one that particularly inspired me was Point Sources. [...]