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24-channel PWM board power output?
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24-channel PWM board power output?

by sinking on Sat Oct 04, 2014 1:26 am

I may have missed it, but how much power can the onboard 5V regulator provide?

I'm going to use a 24V power supply into two of these to drive 5 LEDs in series off each channel, and rather than add even more electronics or another power supply, I'd like to use the 5V output to run my Pro Trinket that will have a couple of other I2C boards connected to it.

Also, under what circumstances would you add a capacitor to the board?

sinking
 
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Re: 24-channel PWM board power output?

by adafruit_support_bill on Sat Oct 04, 2014 9:00 am

The 5v power available depends on the power supply voltage. Since it is a linear regulator, at 24v, for every 20mA you draw it will need to dissipate 80mA as heat. You can probably run your Trinket Pro and some small boards OK. But I wouldn't load it down with too much more.

If you are switching a lot of leds at the same time, a capacitor can help cope with the instantaneous current demands. If you are doing slow fade patterns, it is probably not necessary.

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Re: 24-channel PWM board power output?

by sinking on Mon Oct 06, 2014 7:16 am

Thanks - much appreciated. I'll do a test run using the onboard 5V regulators and keep an eye on the temperatures. If that doesn't look good, I'll add a switch mode buck converter.

The project goes well. Here's a video of progress to date:
https://www.youtube.com/watch?v=gmjBmcB ... RgUHJmN0bw

The channels are currently set to about 1/4 brightness!

Runs off a Trinket Pro, Ultimate GPS module and the two 24-channel PWM drivers. The six 8x8 matrices aren't programmed in yet :-)

Phil.

sinking
 
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Re: 24-channel PWM board power output?

by adafruit_support_bill on Mon Oct 06, 2014 7:34 am

Nice looking clock! Thanks for posting.

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Re: 24-channel PWM board power output?

by sinking on Sat Dec 13, 2014 9:55 pm

Clock is now largely done. Just need to tidy up a frame for it:
https://www.youtube.com/watch?v=H7nqPSoHbQA

The PWM LED controllers are supplied from a 24V pack and then I've added a 5V buck converter for the Pro Trinket, breakouts (GPS, Lux and temperature) and the six 8x8 matrix modules.

My major distraction will programming the various messages :-)

sinking
 
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Joined: Tue Aug 26, 2014 8:31 pm

Please be positive and constructive with your questions and comments.