Alt-BEAM Archive
Message #01691
To: Sean Rigter rigter@cafe.net
From: Dave Hrynkiw dave@solarbotics.com
Date: Fri, 01 May 1998 09:36:42 -0600
Subject: Re: Sun Eater II
According to my own tests, the 4-transistor SunEater needs about
0.06mA, while the other SunEaters and Ken Huntington's Micropower
SE can make do with less than 0.02 mA. It's possible to get (much)
lower values using a 1381.
Given that Solar Engines are supposed to work in light, not
darkness, there is no need to reduce the trigger current to extreme
values. But it obviously shortens the charge cycle if the circuit's
own consumption is modest. Imho anything below 0.1mA is good.
Back to the FLASH SE. 0.3mA doesn't sound all that bad, but is
achieved by reducing the oomph of the circuit. To drive the usual
pager and small recorder motors, you'll have to make changes:
Either do things that will increase the trigger current, or add a
third transistor. Or do something different altogether.
Another disadvantage of the FLASH SE is the tendency to oscillate
when the load gives opportunity. My recorder motor with built-in
cap resulted in nice pointy waves on my scope. In simulated low
light levels, they damped out, but at around 1.6 mA of charge
current, a steady 10KHz appeared. The SunEaters have no trouble
with this motor, and neither has Ken's Micropower SE.
So there is a price to pay for the absence of fancy treshold
detectors and driver stages...
Best,
Steve
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# sbolt@xs4all.nl # Steven Bolt # popular science monthly KIJK #
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