taizoon@ihlpf.ATT.COM (Chinwalla) (04/24/89)
Does anyone have a ckt or recommendation for a chip(s) that is inexpensive and can produce a timing of 120 minutes +- 10 % Taizoon Chinwalla !att!ihlpf!taizoon AT&T Bell Labs
rpw3@amdcad.AMD.COM (Rob Warnock) (04/25/89)
In article <8331@ihlpf.ATT.COM> taizoon@ihlpf.UUCP (Chinwalla,T.) writes: +--------------- | Does anyone have a ckt or recommendation for a chip(s) | that is inexpensive and can produce a timing of 120 minutes +- 10 % +--------------- I would use a 14-stage CMOS counter chip (4027? 4040? sorry, I forget), driven by your favorite 2 Hz oscillator. It's cheap, and if you feed it 2.27 Hz, the topmost bit will tick over every two hours. Rob Warnock Systems Architecture Consultant UUCP: {amdcad,fortune,sun}!redwood!rpw3 DDD: (415)572-2607 USPS: 627 26th Ave, San Mateo, CA 94403
dmt@PacBell.COM (Dave Turner) (04/27/89)
In article <25392@amdcad.AMD.COM> rpw3@amdcad.UUCP (Rob Warnock) writes: |In article <8331@ihlpf.ATT.COM> taizoon@ihlpf.UUCP (Chinwalla,T.) writes: || Does anyone have a ckt or recommendation for a chip(s) || that is inexpensive and can produce a timing of 120 minutes +- 10 % | |I would use a 14-stage CMOS counter chip (4027? 4040? sorry, I forget), |driven by your favorite 2 Hz oscillator. It's cheap, and if you feed it |2.27 Hz, the topmost bit will tick over every two hours. I don't know how the circuit will be used but this seems to be overkill. A simple 555 timer seems like it would be sufficient for this. -- Dave Turner 415/542-1299 {att,bellcore,sun,ames,pyramid}!pacbell!dmt
psfales@ihlpb.ATT.COM (Peter Fales) (04/27/89)
In article <4783@ptsfa.PacBell.COM>, dmt@PacBell.COM (Dave Turner) writes: > In article <25392@amdcad.AMD.COM> rpw3@amdcad.UUCP (Rob Warnock) writes: > |In article <8331@ihlpf.ATT.COM> taizoon@ihlpf.UUCP (Chinwalla,T.) writes: > || Does anyone have a ckt or recommendation for a chip(s) > || that is inexpensive and can produce a timing of 120 minutes +- 10 % > | > |I would use a 14-stage CMOS counter chip (4027? 4040? sorry, I forget), > |driven by your favorite 2 Hz oscillator. It's cheap, and if you feed it > |2.27 Hz, the topmost bit will tick over every two hours. > > I don't know how the circuit will be used but this seems to be overkill. > > A simple 555 timer seems like it would be sufficient for this. 555 circuits run into some problems when used for long timing periods like this. Large, low-leakage capacitors are required, and small temperature drifts can result in a large change in the time constant. I remember reading that someone (Exar?) has integrated a 555 and a multistage counter on a single chip for exactly this application. As I recall, they could get timing periods of DAYS with inexepensive components. f i l l -- Peter Fales AT&T, Room 5B-414 2000 N. Naperville Rd. UUCP: ...att!ihlpb!psfales Naperville, IL 60566 Domain: psfales@ihlpb.att.com work: (312) 979-8031
tindle@ms.uky.edu (Ken Tindle) (04/28/89)
Why not try a XR2240 long range timer? It uses digital counting to generate long but accurate delays. --------------------------\ /------------------------------------------ INTERNET:tindle@ms.uky.edu | "I heard you." -Kirk BITNET:tindle@ukma.bitnet | "He simply could not believe his ears." Ken Tindle - Lexington, KY | -Spock, The Trouble With Tribbles --------------------------/ \------------------------------------------
smadi@rlgvax.UUCP (Smadi Paradise) (04/29/89)
Motorola has a CMOS chip which contains an oscillator, a programmable devider along with some smart reset and output logic. It may be numbered MC14536 (my CMOS data book is 5k miles away :-(). -- On (a guest of uunet!rlgvax!smadi) Paradise
spcecdt@ssyx.ucsc.edu (Space Cadet) (04/30/89)
The 14-stage CMOS counter is the 4020. But, if you want a timer, use the 4060 instead. It is a 14 stage counter too, but includes a dual- inverter oscillator on the chip. A couple of resistors and a capacitor are all that you'd need with the IC for your 2-hour counter. One of my favorite chips... :-) John DuBois spcecdt@ucscb.ucsc.edu ...!ucbvax!ucscc!ucscb!spcecdt