Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!gatech!bloom-beacon!eru!luth!sunic!tut!santra!saha.hut.fi!c37189h From: c37189h@saha.hut.fi (Suomalainen Harri Olavi) Newsgroups: sci.electronics Subject: Re: 555 IC Timer help needed Message-ID: <25513@santra.UUCP> Date: 26 Sep 89 07:45:38 GMT References: <169@uwm.edu> <568@limbic.UUCP> Sender: news@santra.UUCP Reply-To: c37189h@saha.hut.fi (Suomalainen Harri Olavi) Organization: Helsinki University of Technology, Finland Lines: 14 In article <568@limbic.UUCP> gil@limbic.UUCP (Gil Kloepfer Jr.) writes: >I've read it is unwise to make R1 any smaller than 1K ohm. You're absolutely rigth about that: Pin #7 is a collector of an internal transistor while the emitter is connected to ground. With too small a resistance between pin #7 and positive supply rail the transistor will certainly get damaged! I believe R2 could be equal to 0 ohms without any damage to the chip. At leats according to the internal connection diagram I've got no harm should be done nor should it affect harmfully to working of 555 chip. --- E-mail: c37189h@saha.hut.fi * If you're feeling good, don't * UUCP: ...!mcvax!santra!saha!c37189h * worry - You'll get over it! *