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- Newsgroups: sci.electronics
- Path: sparky!uunet!mcsun!sun4nl!dutrun!donau!dutecag.et.tudelft.nl!knop
- From: knop@dutecag.et.tudelft.nl (Peter Knoppers)
- Subject: Re: Simple transistor project (Q)
- Message-ID: <1992Aug17.122438.20238@donau.et.tudelft.nl>
- Sender: news@donau.et.tudelft.nl (UseNet News System)
- Nntp-Posting-Host: dutecag.et.tudelft.nl
- Organization: Delft University of Technology, Dept. of Electrical Engineering
- References: <1992Aug13.062418.999@cs.uri.edu> <1992Aug13.100326.3698@donau.et.tudelft.nl> <1992Aug14.114202.3925@donau.et.tudelft.nl> <2524@tau-ceti.isc-br.com>
- Date: Mon, 17 Aug 1992 12:24:38 GMT
- Lines: 21
-
- jimc@tau-ceti.isc-br.com (Jim Cathey) writes:
-
- >In article <1992Aug14.114202.3925@donau.et.tudelft.nl> knop@dutecag.et.tudelft.nl (Peter Knoppers) writes:
- >>If it is not possible to ensure that the input signal is low at the
- >>end of the 1 second period, you'll have to add some logic that switches
- >>off the trigger signal of the 555 after it has been started until the
- >>logic input signal has gone low again.
-
- >Or, you could capacitively couple the trigger signal. Saves some gates,
- >if you don't get them for free.
-
- That may create a signal that rises above the VCC level or drops below the
- GND level. Such a signal may trigger a parasitic thyristor in the chip that
- short-circuits the power supply pins and subsequently destroys the chip,
- the power supply, or both.
-
- The signals on input pins of most digital chips may NEVER exceed the range
- of the power pins (GND to VCC) by more than about 0.5 Volts. Permanent
- damage may occur if this rule is violated.
-
- Peter Knoppers - knop@duteca.et.tudelft.nl
-