Highcooley

Bidirectional two lead duocolor LED BLM

3 posts in this topic

Has anybody built a BLM with bidirectional two lead duocolor LEDs, where the two colors can be adressed by reversing the polarity?

 

bicolor_two_lead.PNG

 

How would the scan circuit have to be designed in order to work with the standard midibox solutions? Of course, compared with the scalar board, the resistor-transistor arrangement of IC2 could be placed next to IC3 and another 74HC595 next to IC2. But then the scan algorythm would also have to scan each color sequentially.

 

 

Why am I looking for such a solution? I evaluated the  the switch of choice for my Synth project:

 

TC011-4.jpg

 

For my needs, I only have single color buttons (yellow). But this button could also be interesting for BLM applications where duocolor would be needed (RGB is available as well).

 

I am working on a versatile matrix PCB solution for my synth project, where single rows of a matrix can be cut to the desired length and the LEDs can be adressed individually via solder jumpers. These smaller boards can be bought much cheaper in small quantities than the propriatary matrix boards and in my case serve different needs.

Edited by Highcooley

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Not possible to use a bi-directional LED as far as I know, unless you can "Charlieplex" the IO pins. TK and others have said this in several different threads.

 

Any idea on cost for the RGB variant? The only thing similar that I know of is the Omron B3W-9000-RG2N, which is more than $2.50 a pop in quantity. Sadly the Wellbuying RGB is common anode, again not compatible with the SCALAR circuit at the moment. 

 

http://www.wellbuying.com.tw/UP_pdf/tc011%20series.pdf

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Too bad. Although, I would not care if I needed to design another scan circuit. But as long as the midibox_NG cannot scan "Charlieplexed" (good to know what the "official" name is) matrices, it wouldn't work anyway.

 

If you are interested in the RBG price, I can pm you the contact of the salesperson.

Edited by Highcooley

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