Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!wuarchive!gem.mps.ohio-state.edu!apple!mips!vaso
From: vaso@mips.COM (Vaso Bovan)
Newsgroups: sci.electronics
Subject: Re: 555 IC Timer help needed
Summary: Differences among manufacturers
Message-ID: <29060@buckaroo.mips.COM>
Date: 7 Oct 89 03:54:00 GMT
References: <169@uwm.edu> <568@limbic.UUCP> <3356@ccnysci.UUCP>
Reply-To: vaso@mips.COM (Vaso Bovan)
Organization: MIPS Computer Systems, Sunnyvale, CA
Lines: 14

In article <3356@ccnysci.UUCP> sukenick@ccnysci.UUCP (SYG) writes:
>
>Be very careful with equations: I've seen different equations for 555's,
>duty cycles, frequencies, etc. depending upon the manufacturer. 
>Also, some will work even after pin 7 is shorted to pin 8, others
>will blow out immediately if the resistance is lower than 1k or 200 ohms.

I haven't been following this thread, so I don't know if this has been
mentioned: All 555 timers are not made the same. For instance, pin 6
overrides pin 2 for the National LM555H, but pin 2 overrides pin 6 for the
Signetics NE555V. This is covered in a short note: "Bistable Action of 555
Varies with Manufacturer", originally published in Electronics magazine
(date unknown) and reprinted in "Design Techniques for Electronics
Engineers," McGraw-Hill 1977, pg 32.