Self generating, therefore selenium (or possibly silicon). There is no bias so it's not a photoconductor. I'm sure it's called out in the -24P manual.
-John =============== > Thank you everyone for your comments, and if I've got it right Brooke, if > you paste this into your browser: > > http://www.flickr.com//photos/75ohm/sets/72157629019710615/show/ > > you should get a quick tour and a movie! > > This is indeed a tuning fork driving a synchronous motor that has a > perforated disc on its shaft. The whole unit operates as it should and the > quality of manufacture is superb, so I'm reluctant to pull it apart but I > am curious as to the type of photocell it uses. It seems very small and > the dates on many of the components suggest manufacture in the mid to late > 1950s so what was around to do the job at that time? There is no cathode > bias on the "voltage amplifier" that it feeds which suggests it s > Photovoltaic rather than Photoconductive. > > Thanks again for your replies, > > John H. > > > On 24 Jan 2012, at 22:34, Brooke Clarke wrote: > >> Hi John: >> >> Is there a photo of the freq std on line? >> >> Have Fun, >> >> Brooke Clarke >> http://www.PRC68.com >> http://www.end2partygovernment.com/Brooke4Congress.html >> >> >> John Howell wrote: >>> Thanks Bob, >>> >>> If it helps the switched frequencies are: 0, 10, 20, 40, 60, 80, 100, >>> 120, 140, 160, 180, 190Hz. >>> >>> John. >>> >>> On 24 Jan 2012, at 22:09, Bob Camp wrote: >>> >>>> Hi >>>> >>>> Sounds about right for calibrating / verifying vibrating reed >>>> frequency >>>> readouts. >>>> >>>> Bob >>>> >>>> -----Original Message----- >>>> From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] >>>> On >>>> Behalf Of John Howell >>>> Sent: Tuesday, January 24, 2012 5:00 PM >>>> To: Discussion of precise time and frequency measurement >>>> Subject: [time-nuts] US Army Frequency Standard >>>> >>>> Hi All, >>>> >>>> I recently obtained a curious Low Frequency Standard dating from the >>>> late >>>> 1950s. Its output can be switched to a number of frequencies from 10 >>>> to >>>> 190Hz, derived from a tuning fork. It is marked "Signal Corps" and "US >>>> Army" >>>> with a type number TS-65D/FMQ-1. >>>> >>>> >>>> Does anyone have any information about this unit, in particular what >>>> it was >>>> used for and why the strange negative going pulse output and specific >>>> frequencies. >>>> >>>> Thanks in advance, >>>> John H. >>>> >>>> _______________________________________________ >>>> time-nuts mailing list -- time-nuts@febo.com >>>> To unsubscribe, go to >>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>>> and follow the instructions there. >>>> >>>> >>>> _______________________________________________ >>>> time-nuts mailing list -- time-nuts@febo.com >>>> To unsubscribe, go to >>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>>> and follow the instructions there. >>> >>> _______________________________________________ >>> time-nuts mailing list -- time-nuts@febo.com >>> To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >>> >>> >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.