That 'flag' feature can be found on the very early (1930s) Telechron digital display clock, the model 8B01, as a separator between the hours and minutes digits. A lever on the back panel allowed the user to reset the flag from red to white when power was applied. Loss of AC power meant the synchronous motor that drove the digital dial drum mechanism lost it's magnetic field - which allowed the flag to 'fall' and display as red. The 8B01 has often been described as the world's first digital clock-is this true?- Not sure. DaveB, NZ
-----Original Message----- From: time-nuts [mailto:[email protected]] On Behalf Of Hal Murray Sent: Saturday, February 13, 2021 18:49 To: Discussion of precise time and frequency measurement Cc: [email protected] Subject: Re: [time-nuts] The need for quartz crystals and mains frequency (was: Mains Frequency) [email protected] said: > And, please do not forget that modern mains frequency control is > something quite recent as well. Especially outside (west) Europe. > Having mains frequency powered clocks being off several minutes per > month was the norm > 50-70 years ago. I have a (fuzzy) data point from ~60 years ago. I was in high school and got to tag along with a quick tour through Niagara Mohawk's control room. They were the power company for a large part of upstate New York, including Syracuse where I lived. I remember somebody pointing out a pair of clocks on the wall, one driven by the line. I wasn't enough of a time-nut to inquire about the source for the reference clock. ---------- Has anybody seen a good writeup on the history of clocks running off the line frequency and power lines being used for timekeeping? ---------- Anybody else remember the little red dot that was on a swinging flag behind a little hole? That was the analog equivalent of blinking 00:00. When you set the time on a clock, the flag swung up and stuck to a magnetic part of the motor. The color on the part of the flag visible through the hole in that position matched the color of the face. When power was lost, gravity pulled the flag down and that part was painted red. -- These are my opinions. I hate spam. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
