🚀 go-pugleaf

In article <1992Aug17.122438.20238@donau.et.tudelft.nl> knop@dutecag.et.tudelft.nl (Peter Knoppers) writes:
>>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.

Do 555's have parasitic thyristors?  Bipolar or CMOS version?  Anyways,
proper sizing of the trigger cap, perhaps some series resistance and
maybe even a diode clamp couldn't hurt. 

>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.

A 555 is (by every measure I've heard) an _analog_ component.  Who knows
what evil little tricks lurk inside it, or just how it's fabricated. 
The part has been (ab)used by industry for years, in all manner of
applications, many of which it is ill-suited for.  I'd still look
into the approach, rather than throw another gate package into a
design.

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