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Glass Block Display is Growing

December 23rd, 2009

Glass Block Display ColumnsCJDavis and I were at the hive until about 1:20 am this morning working on finishing up a second strand of LED lights for the Glass Block Matrix LED Display.

In this image we are diffusing the LED’s with a sheet of paper towel which causes a nice soft glow, however it greatly reduces the brightness.  Therefore we are leaving the paper towels off even though they make for a great picture and viewing experience from inside the bathroom.

We have had some technical issues with both the RGB LEDs and the wiring system we are using.  A good amount of the LED’s seem to have an issue where they will turn on even when the anode wire is not connected to anything.  We are talking nothing, like it is just soldered into a proto-board.  Current speculation is that either the LED’s are bad or the proto-boards are bad.

Another problem we have been having is that originally we were using Cat-5 to wire up each anode for the 8 LED’s in a column, however the current in the twisted pairs was enough to induce a current in the second pair causing issues with LEDs coming on when they are not supposed to.  This is a fairly limited problem so far as the LEDs only glow faintly.  In any case we are altering how we wire up future anodes.

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  1. cjdavis
    December 27th, 2009 at 23:49 | #1

    Third option on the technical issues is that the anode lines are not being completely grounded when they should be.

    Fourth is inductive cross-talk on the anodes, which are running over cat-5 twisted pair (bad), unshielded cat-3 (better), or shielded cat-3 (best).

    I think it’s a combo of all of the above.

  2. Ralph
    July 10th, 2010 at 15:57 | #2

    Late to the discussion, but if one wire of each pair is grounded, wouldn’t that minimize the induced current?

    1 – signal
    2 – gnd
    3 – signal
    4 – gnd
    5 – signal
    6 – gnd

    7 – signal
    8 – gnd

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