Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!wuarchive!udel!princeton!cs!cs.Princeton.EDU!yh From: yh@cs.Princeton.EDU (Yoichi Hamazaki) Newsgroups: sci.electronics Subject: Re: Sidereal Time Clock Message-ID: <5314@rossignol.Princeton.EDU> Date: 13 Dec 90 16:18:54 GMT References: <1833@umriscc.isc.umr.edu> Sender: news@cs.Princeton.EDU Distribution: sci.electronics Organization: Dept. of Computer Science, Princeton University Lines: 21 One of simplest(and may be cheapest) way to get clock working between 0:00:00 to 23:56:04 is modifing commercial digital alarm clock. 1) Buy digital alarm clock of your faverite. (AC powered or Battey, LED,FLD or LCD) 2) make two mono-stable multivibrator(One-shot) using CMOS or TTL. Pulse width of them are 4seconds and 0.09 seconds. 3) Find alarm signal from clock LSI and connect to 4sec. One-shot trigger. 4) Connect output of 4sec. one-shot to trigger of 0.09sec one-shot. 5) Connect output of 0.09sec one-shot to 'set to 0:00:00' switch input. (Usually, both of time-adjust switches) 6) Turn on clock, adjust time, and set alarm to '23:56' When clock becomes 23:56, 4sec one-shot makes pulse, 4 seconds later 'set to 0:00:00' signal(s) is fed to clock for 0.09 seconds. Then clock count time from 0:00:00 again. -- Yoichi HAMAZAKI Dept. computer science, Princeton Univ. (from Electrotechnical Lab. (ETL), Japan) E-mail: yh@princeton.EDU Ham: W2/JR1OQY (2m & 70cm)