Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site redwood.UUCP Path: utzoo!linus!decvax!decwrl!amdcad!fortune!foros1!redwood!rpw3 From: rpw3@redwood.UUCP (Rob Warnock) Newsgroups: net.micro Subject: Re: mysterious resistor Message-ID: <75@redwood.UUCP> Date: Sat, 3-Nov-84 05:48:53 EST Article-I.D.: redwood.75 Posted: Sat Nov 3 05:48:53 1984 Date-Received: Sun, 4-Nov-84 04:57:19 EST References: <4559@utzoo.UUCP> Organization: [Consultant], Foster City, CA Lines: 23 +--------------- | ...The mystery part is, there is a 22 megohm resistor across | the "inside" ends of the 100k resistors. Any idea what it's for? +--------------- Just a guess... in case the ring detector gets connected to a long telephone line that is NOT connected at the other end (the C.O.), the 22 meg resistor will prevent static charge buildup which could eventually puncture the .01 capacitor (which has only a finite breakdown voltage). It may also be (and this is more likely) to protect the whole thing during packing and shipping (in plastic wrappings). I have done similar things designing interface cards (controllers) which had MOS pins straight on the bus (and no TTL) -- put a very high resistor between the pin and +5 (which is == 0 during shipping) to prevent static buildup during shipping and handling. Rob Warnock UUCP: {ihnp4,ucbvax!amd}!fortune!redwood!rpw3 DDD: (415)572-2607 Envoy: rob.warnock/kingfisher USPS: 510 Trinidad Ln, Foster City, CA 94404