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HowTo: 128 chan derivative of Hill's 320 design w/ PCB and Linux driver
( Don Law)
Step 3 : The PCB - population, installation
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| | Here you see a photo of the master controller finished. I populated it with the chips and soldered CAT5 cable to the outputs. The cable to the parallel port on the computer comes out the top left, and the power connector comes out the bottom left.
**IMPORTANT**The silkscreen has an error - it labels pin 1 of the DB-25 connector at the wrong end. Pin 1 of the DB-25 connector is toward the top of the board. Check your parallel port connection against the schematic, not against the label on the silkscreen.
My basic appoach is to have the master controller send out logic level (5V) signals to subcontrollers. I have 15 subcontrollers, each of which can handle 6 channels. I chose 6 because 1) I wanted to use CAT5 cable, which has 8 conductors, and I needed one for ground 2) the lights in my yard tend to group is sets of 6.
An estute computerchristmas.com user could probably figure out how to make 8 channel subcontrollers by using the ground on the power cord, and thereby all 8 lines in the CAT5 cable for signal.
The advantage of only sending the logic level signal out to the subcontroller is in the wiring. I only have to run CAT5, which is cheap and easy to work with, from the computer to where the lights are. The CAT5 connectors are cheap. The controller only needs one power cable for all 6 channels, and can just take it from the nearest power source. This cuts down on the extension cords and power wiring. I just place the subcontrollers around my yard in close proximity to the 6 light strings each of them control.
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