Alt-BEAM Archive
Message #01070
To: grant mckee gmbeam@hotmail.com
From: Steven Bolt sbolt@xs4all.nl
Date: Sun, 28 Feb 1999 11:31:27 +0100 (CET)
Subject: [alt-beam] Re: Quest for an efficient SE
On Sun, 28 Feb 1999, grant mckee wrote:
---8<---
> and a power efficient motor (best Ive seen is about 20 mA) there
> probably is better just havn't seen them
Efficiency is not the same as low current. Solar Engines usually
convert light into brief power bursts, putting a premium on motors
with low inertia. That means low mass and small diameter, making
pager motors hard to beat. Small recorder and servo motors aren't
bad, however. Their larger diameter actually makes it easier to
accelerate the entire `bot, and they are more efficient at the
lower rpm values which an ungeared photovore needs. They also tend
to be less fragile, with much better bearings and commutators.
Their weight is not so much of a disadvantage as you might think.
> ok the 1381 is probably the most effecient trigger out there right now
It consumes very little current. On the other hand, the trigger
level is not adjustable, and the effeciency of the entire `bot
depends to a large extend on getting the switch-on and switch-off
trigger levels just right. SunEater_II and variations on that
theme do a good job there. And their quiescent current consumption
is low enough to make no noticeable difference in reasonable light.
> There is a problem with pager motor- they are mostly speed and
> not much torque, SR's (solar rollers) can be made with a wheel
> directly driven by the pager motor but to get the SR moving takes a
> large amout of current. To overcome this the pager motor can be geared
> down but in doing this there is a loss of power.
>
> solution?
>
> heres my idea use a 555 as a pulse width modulator to the pager motor.
> in doing this the pager motor would be slowed down as well as it would
> run on less power.
I don't think pwm is likely to help solarollers and photovores
much. You'll be adding some weight, generating the frequency will
consume some power and torque remains low. But I hope you'll prove
me wrong!
Best,
Steve
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# sbolt@xs4all.nl # Steven Bolt # popular science monthly KIJK #
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