Alt-BEAM Archive
Message #01272
To: Justin jaf60@student.canterbury.ac.nz
From: Steven Bolt sbolt@xs4all.nl
Date: Thu, 4 Mar 1999 19:27:36 +0100 (CET)
Subject: [alt-beam] Re: advanced circuits
On Fri, 5 Mar 1999, Justin wrote:
> > That's all very well, but you didn't answer my question. What *is*
> > supposed to be difficult about driving non-inductive loads? I'm
> > really curious.
>
> Nothing difficult about it, it's just that the two most basic SE
> circuits (that most people start out with) don't.
Are you sure?
Even the humblest sorry 2-transistor excuse for an SE does not
require its load to be inductive. It merely needs something with a
relatively low initial resistance. Try an ordinary low-voltage
light bulb - you'll find it flashing happily, and it's hardly
inductive.
> My thoughts on Alf is that it has comparible number of components with
> many photovore designs that do not drive non-inductive loads (not to
> mention it has a Suneater-II style SE on board to add spice to the
> deal), hence it's kind of a feature. Maybe I'm just obsessed with making
> things small :-)
Small and light do matter if you want motion out of a thumb-sized
solar panel. Go SMT! 74HC logic in SMT is *very* tiny :)
Which makes me remember another posting of yours. Recycling SMT
transistors and diodes. Not too long ago I designed a simple radio
control set for indoor model aircraft - making me take small and
*light* very serious indeed. Here you have some of the transistors
I used:
`Normal' equivalent SMT designation on case
BC549C BC847C 1GS26
BC559C BC857C 3GS25
BC337-25 BC817-25 6BS17
The equivalency does not cover power dissipation, of course. But
when switching properly, the BC817 will pull the usual motors. It
has the same hFE @ Ic and the same VCEsat as the BC337.
Oh, and you can indeed find diodes in that same (sot-23) case.
---8<---
> Besides which, we can always take a lession from the software industry
> and wire up our superlatives in series.
> Coming soon:
> The SuperDelux AdvancedVer2++ MegaMasterPhotovoreXtreme17.530c-47
> [batteries not included]
That's probably best: Really pore it on, to make sure that the
`advanced' bit is taken with sufficient salt.
Best,
Steve
----------------------------------------------------------------------
# sbolt@xs4all.nl # Steven Bolt # popular science monthly KIJK #
----------------------------------------------------------------------
------------------------------------------------------------------------
eGroup home: http://www.eGroups.com/list/alt-beam
Free Web-based e-mail groups by eGroups.com
Home