Alt-BEAM Archive
Message #05122
To: beam@sgiblab.sgi.com
From: Darrell Johnson beamtastic@yahoo.com
Date: Thu, 8 Jul 1999 11:58:58 -0700 (PDT)
Subject: [alt-beam] Re: Power Smart Head
--- Don Papp wrote:
> Out of curiosity, anyone else have trouble getting
> the FLED to
> work with the PSH cct properly? The FLED I have
> lights up very dimly -
> not enough to even see unless the room is dark. I
> thought perhaps my FLED
> had too high of a Vf, but some tinkering and
> substitution didn't really
> help. If you're in the same boat, here's a couple
> alternatives:
>
> 1) Live without a "lock" LED
>
> 2) Make a FLED-alike with some extra components
>
ok.. First off, it's not a "lock" LED.. the FLED isn't even a part of
the PSH circuit, it's a part of the SE that I'm using.. All the FLED
does is blink when the first inverter of the 1381 latch SE goes low...
This means the SE has triggered and the circuit is 'active' it blinks
whether the head is moving or locked.. The FLED isn't even necessary..
it's just some eye candy for when the head is just sitting there
waiting for someting to move.
Second off, it doesn't use very much current at all.. any LED you use
is going to use way more current.. the 2 LDRs are the most inefficient
part of the circuit.. but my PSH still increases it's charge while it's
active, sitting under a desk lamp.. I'd say that probably good
enough,and the FLED doesnt' use *any* current while the SE is charging,
because it is not on.
As for the FLED I'm using.. just the standard FLED that Radio Shack
sells... don't have any of the specs on it though..
If your FLED is dim, try a smaller resistor in place of the 3.3k that
will let more current through. If your FLED starts blinking before the
1381 triggers, you have the FLED in backwards..
anyways, hope this helps.. I know I need to get some more info on my
web page...
-darrell
===
_______________________________
BICOREEOS..They're BEAMtastic!!
http://home.pacbell.net/wundoba
------------------------------------------------------------------------
eGroups.com home: http://www.egroups.com/group/alt-beam
http://www.egroups.com
- Simplifying group communications
Home