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mister_wavey
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Location: Abergavenny, Wales, UK
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Q: Gertboard powered away from pi

Wed Oct 03, 2012 7:53 am

Hi, if I wanted to use the the Gertboard like a standalone Arduino, disconnected from the pi, what would be the recommended way to power it?

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Gert van Loo
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Re: Q: Gertboard powered away from pi

Wed Oct 03, 2012 12:57 pm

It has a 3v3 regulator which is fed from the Raspberry-Pi 5V.
The output of that goes to a jumper and from there to the rest of the board.
You have two options:
- Connect 5V** before the 3V3 regulator.
- Connect your own 3V3 power to the jumper on the board

I found the board uses very little current but then I have not tried to drive all outputs at the same time yet.

** I have not tested this but you could also connect a higher voltage.
The regulator gets warmer and depending on how much current you take out and how high a voltage
you put in you may have to add a heat sink. Beware that some 3V3 regulators have a max input voltage of 7V.
I do NOT know what 3V3 regulator is used. Especially as there are now Tandy kits (and hopefully soon)
Farnell kits which are unlikely to have the same parts.

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Tandy
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Location: Oxford
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Re: Q: Gertboard powered away from pi

Wed Oct 03, 2012 1:21 pm

The 3.3V Regulator supplied in the Tandy kit is an LM3940 specifically designed for 5V to 3.3V conversion with a low drop out Voltage of 0.5V and high current rating of 1A. This means that you can run the board from as little as 3 AA dry cells (3x1.5V=4.5V) or 4 rechargable cells (4x1.2V=4.8V) if you want. However the absoloute maximum rating for the input Voltage of this regulator is 7.5V so wouldn't suggest running it at much more than 6V to avoid needing a heatsink.
Tandy - The home of electronics - www.tandyonline.co.uk

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mister_wavey
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Location: Abergavenny, Wales, UK
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Re: Q: Gertboard powered away from pi

Wed Oct 03, 2012 2:07 pm

Thanks guys!

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