Alt-BEAM Archive
Message #03217
To: beam@corp.sgi.com
From: Steven Bolt sbolt@xs4all.nl
Date: Tue, 11 May 1999 18:34:16 +0200 (CEST)
Subject: Re: SMD SE
If you want to stay with a switch-off level (instead of a
switch-off time), increasing that level is probably the most
efficient solution. You might try a 1N4148 diode in series with the
2K2 resistor (anode towards the 3906 base). That will make the SE
switch off at about 1V instead of less than 0.8V. Check if the
level is high enough to allow a restart without that resistor over
the coil. If not, add another diode.
Of course this will shorten the pulse to the coil. If it becomes
too short, you need a larger storage cap.
---8<---
However, if you use for instance a 1N4148, your dropout
(switch-off) level won't rise 0.7V, but just 0.2V, or perhaps 0.3V.
There just isn't enough current passing through the diode. A LED
may cause too much of an increase to be practical, as there always
is a brief switch-on voltage dip.
Best,
Steve
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# sbolt@xs4all.nl # Steven Bolt # popular science monthly KIJK #
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