Alt-BEAM Archive
Message #05231
To: beam@sgiblab.sgi.com
From: Bob Shannon bshannon@tiac.net
Date: Sat, 10 Jul 1999 10:58:38 -0400
Subject: [alt-beam] Re: Something funny with the 1382 voltage triggers?
Steven Bolt wrote:
> On Fri, 9 Jul 1999, Terry Newton wrote:
>
> > Could be SM 1381's don't like having their low output being
> > pulled high by something else, that's not exactly something
> > you want to do with output stages. If you try that with any
> > kind of power you'll likely get smoke or other flakiness.
>
> The typical 2-transistor latch/driver wastes about 4mA max. when
> pulling an active low 1381 output to the about 0.7 allowed by the
> base-emitter diode of the driver transistor. Imho not enough to do
> damage, and not very significant in terms of efficiency, for this
> circuit...
More importantly, this does not seem to be the problem here.
If it were, the correct solution would be to use the open collector
versions of the 1382, adding nothing to the circuit.
> > If that's the problem then maybe just a single resistor,
> ---8<---
> > A 1N914 in series with the 1381 output (anode to 1381, cathode
> ---8<---
>
> With all those resistors and diodes being added by Wilf, Bob and
> you, the component count is about what you need for a proper latch
> and driver :)
It only takes one diode Steven.
Maybe we have had enough latch bashing, in light of the fact that your
still
not seeing the real problem here?
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