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Word Clock Learn Guide with Trinket
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Word Clock Learn Guide with Trinket

by crazycanuck on Mon Mar 18, 2019 11:51 am

Hi,

Recent Make Magazine article featured the Learn guide https://learn.adafruit.com/neomatrix-8x8-word-clock to build a nice word clock using Trinket and Neomatrix. At max white brightness, my understanding is that each Neopixel on the Neomatric pulls 60mA. With the example picture shown in the guide (17 characters lit up) we would then have approximately 1A drawn. The circuit assembly in the guide shows the Neomatrix connected to the 5V pin on the Trinket, but the spec seems to indicate that the onboard regulator is limited to 150 mA max. Am I missing something? Perhaps the connection should be on the Bus pin on the Trinket? I assume that if powered via USB, the Bus pin would supply up to max available from USB power supply and not be limited by onboard regulator?

Thanks

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Re: Word Clock Learn Guide with Trinket

by adafruit_support_mike on Tue Mar 19, 2019 2:17 am

The 150mA limit is for the 3.3V regulator. The 5V regulator can handle the NeoMatrix's current.

If you want to be extra sure, you can move the NeoMatrix power connection from the 5V pin to the USB pin. That's connected directly to the 5V USB line, and doesn't go through the onboard regulator.

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Re: Word Clock Learn Guide with Trinket

by crazycanuck on Tue Mar 19, 2019 11:24 am

Hi, thanks for the reply. I think we may be both correct, but talking about different Trinkets. The learning guide had the Trinket Pro 5V on the parts list and the product page https://www.adafruit.com/product/2000 still has max output from regulator at 150 mA and I don't think this would be sufficient. Perhaps your earlier response was in reference to the Trinket M0?

crazycanuck
 
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Re: Word Clock Learn Guide with Trinket

by adafruit_support_mike on Tue Mar 19, 2019 11:57 pm

crazycanuck wrote:Perhaps your earlier response was in reference to the Trinket M0?

No, I was talking about the Pro Trinket, but could have been clearer.

There are two versions of the Pro Trinket: one that operates at 3.3V and one that operates at 5V. The one with the 3.3V regulator has a 150mA current limit. The one with a 5V regulator has a higher current limit, but adding that detail to the tutorial would make things complicated. In all cases, if someone is concerned about the amount of power they can get from a regulated 5V output, the default answer is to bypass the regulator and use the USB pin.

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Please be positive and constructive with your questions and comments.