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Working with Led Arrays
For years I had wanted to play with LED arrays. The cost was the limiting factor. Now they are outdated and commonly available for as little as 8 for $20.
LED VU meters
My first project was to add LED VU meters to audio mixers. Most of the inexpensive mixers do not have meters on each channel. That makes it harder to identify who is on what channel and who is louder than everybody else. Here is an easy to build device that can add meters to each channel of a mixer. This takes 15 1/4 inch plugs to a 25 pin printer port type of jack on the controller. Then a 15 pin jack connects the display up to the controller.
LED Signs
My first LED sign actually used diodes to produce the desired letters. It displayed 'on the air' to warn as to when a transmitter was on.
The next design used the printer port of a computer to control the LED display. It was published in Nuts and Volts magazine. It used spaced out displays with no scrolling or anything like that.
Computer Controlled LED sign.
My next sign used much larger LED arrays, and they were mounted next to each other so the sign could scroll. The IC's to control it were all tucked away on the left side of the sign. The larger displays turned out to be Common Cathode devices so it took a littler redesigning to get it to work properly. Only 5 of the arrays fit on the circuit board. So as I later added more arrays I had to extend the length of the circuit board to fit them. Four pair Telephone wire was used to reach from the IC's to the arrays.
My latest sign features combined Red and Green LED arrays to add multiple colors to the display. If both colors are on it gives a yellowish color. These arrays were smaller than the other ones I have worked with. Each display has two latches, one for each color. Both latches must be set up before it is turned on.
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