[dorkbotpdx-blabber] Re: solor powered Dorkboard, fact or fiction?

[Laen]

A running dorkboard on its own (not running any external components
like LEDs) is about 20mA at 5V.  I don't know what it would be at 3V.
I think the Atmega168Vs run a bit less, but I haven't hooked them up
to a meter.

For the capacitor, I _think_ the math goes like this (someone correct
me if I'm wrong!)

Volts^2 * Farads = Joules of energy storage.
Volts * Farads / amps = the amount of time it can put out that amount
of amps.  In practice, it'll be much lower, because the voltage will
drop as you drain power.

So:
a 3V, 1F supercap would run a Dorkboard for:
3V*1F / 20 milliamps == 2.5 minutes.

(By the way, google Calculator handles these conversions really well.
Enter "3V*1F/20 milliamps" into a google search, and you'll get that
answer.)

-Laen

On Mar 31, 6:36 pm, scott winner <sc... at scenbot.com> wrote:
> I am looking for some advice or tips.  
> Here is my project,  
>
> I want to run my Dorkboard on solor
> power.  Don is setting me up with a 3 volt chip.  That will help a
> lot.  I am going to model the control after the Solorbotics voltage
> trigger; solor energy is stored in caps then dumped into the
> Dorkboard when a critical voltage is reached.
>
> So my question for the ether is, what
> size caps?  How much power needs to be stored to run the Dorkboard?
> No motor function, just to blink the light.  I know how much to run
> the motors that will be on a separate circuit.
>
> Ok go nuts folks.  
>
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