foot pedal power

Hal Murray hmurray at
Tue Jan 25 19:02:08 EST 2011

> Given that it's making 60-80W of power it's safe to assume if it's 70%
> efficient you're talking about needing 100W of actual energy.

60-80 W is the max that unit can put out.  An XO can't use that much 

I have the green wall-wart for an XO-1 plugged into a meter.  It only reads 
power with a resolution of 1 watt.  The most I've seen is 19 watts.

With the CPU idle (not sleeping), backlight on, and battery charged, it takes 
7 watts.  If the CPU and memory are working, it takes 9 watts.

10-20 watts seems within reason to me.  Small kids might have trouble putting 
out that much power for extended periods of time.  For calibration, world 
class athletes (human powered aircraft) can put out 750 watts (1 horsepower) 
for an hour.  Big muscles can put out more power than small ones: legs are 
better than arms.  Using the thigh would probably work better than the calf 
but may not be as convenient.

If anybody does the experiment, especially if you test kids, please let me/us 
know the results.

Google for >bicycle powered TV< gets lots of info.

Here is a good start:


If a foot powered charger is going to be really useful for an XO, I think it 
will need some feedback mechanism so you can tell if you are pushing hard 
enough but not so hard that you are wasting effort.  Force feedback and/or 
sound would probably do it.  Maybe a LED.

These are my opinions, not necessarily my employer's.  I hate spam.

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