Alt-BEAM Archive
Message #00594
To: Dave Hrynkiw dave@solarbotics.com
From: James Wilson jameswilson@globalserve.net
Date: Thu, 18 Feb 1999 18:51:38 -0500
Subject: [alt-beam] Re: Solar Roller
I have found that the addition of a 2.2uF (tantalum) cap accross the motor will
also solve this problem.
Dave Hrynkiw wrote:
> 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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