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Topic: Need help with large thermochromic matrix design (Read 2968 times) previous topic - next topic

aibonewt

Out of desperation to get the thing working, I did try the NPNs as per my sketch and used a separate battery supply for the resistor matrix. It does seem to work now, though I really need a single supply fix. I tried a higher supply voltage to avoid the brown-outs, but even though I stopped the Arduino from resetting I still found the shift registers halted while the matrix was connected. Drat!

Yes Grumpy, the column MOSFETs are the TPC6108s as per your project (you can just see them peeking out from the top of the black thermochromic film in one of the photos). They're switched by the 595 shift registers. They're nice and small, don't get hot, and didn't cost the earth.

Really need to figure this supply out...

Best,

Thomas

CrossRoads

Where are you located? I thought I posted a link to a 5V, 4A supply that would do the trick for you nicely.
http://www.mpja.com/prodinfo.asp?number=18520+PS , $7
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

aibonewt

Ah, nice one CrossRoads!

I'm UK-based, but I'm sure I can get myself something similar fairly easily. So, as long as the amps are high enough (>2.5A?) my board won't brown-out?

Sounds too good to be true, but all the advice I've had so far has been solid so I'm not arguing. This'll slash my component count too, as I won't have to use my NPNs on the final board. Fingers crossed.

Best,

Thomas

CrossRoads

Thomas,
Update your profile to show location, you'll get better suggestions for sources that way.

You could also use seperate sources while you figure out your current needs.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

aibonewt

Done!

I've ordered a local supply to your spec, will try it in a day or two.

Thanks again,

Thomas

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