Alt-BEAM Archive
Message #00566
To: "Chris Daniel" popjester@hotmail.com, beam@corp.sgi.com
From: Dave Hrynkiw dave@solarbotics.com
Date: Wed, 17 Feb 1999 20:45:33 -0700
Subject: [alt-beam] Re: Solar Roller
At 02:11 PM 2/17/99 , Chris Daniel wrote:
>I've built a solar roller, but all it does is buzz when it reaches the
>trigger voltage (2.27V). If I short the motor to ground very quickly
>then it fires properly, and also, if I give the motor a quick spin (in
>the appropriate directio :) with my fingers then it fires. Any ideas?
>I'm using a 0.033uF cap with a 2.7V @ 16mA solar cell. I remember
>someone else had a similar problem recently.
This problem can be traced to at least two (2) places:
(1) Not so efficient motor. If the motor draws more power at startup (when
the most current is drawn) than the cap's internal resistance can
accommodate, the SE won't latch, and buzz instead.
(2) Not so efficient cap. If you mean your cap is actually a 0.033F (not
uF) cap, than this is probably the case. Relating to point 1, most of this
size of cap has a not-so-amazing internal resistance (meaning it's high),
and it can't discharge quick enough to keep the SE going. Try putting a
1000uF (or higher) cap in parallel with it. This will give the motor enough
of a boost to get started, after which it takes much less current to run,
and will be in the realm that the 0.033F cap can keep up with.
Regards,
Dave
---------------------------------------------------------------
"Um, no - that's H,R,Y,N,K,I,W. No, not K,I,U,U, K,I,_W_. Yes,
that's right. Yes, I know it looks like "HOCKYRINK." Yup, only
2 vowels. Pronounciation? _SMITH_".
http://www.solarbotics.com
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