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larussell
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Re: Vintage Time Delay Relay
larussell   8/22/2014 5:17:49 PM
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How about doing the whole thing analog? Each meter can be driven from a timebase like an oscilloscope or analog computer. You can sync between them the same way the horizontal and vertical waveforms are synced in an analog TV, but with more stages. And then sync the whole thing to 50/60 Hz line frequency to keep accurate time.

smpowell
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Re: Sorry to have missed it
smpowell   8/22/2014 2:49:06 PM
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>Good museum (National Museum of USAF) as well, or so I'm told.

It's also huge. Plan on half a day at least.

Dayton also has the (Carillon Historical Park) A legacy of the  days when Dayton was a technological powerhouse in the 19th and early 20th centuries.

GSKrasle
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Freelancer
Re: 32.768kHz crystals
GSKrasle   8/22/2014 1:50:09 PM
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Yeah, parabolic. A-T is third-order. For both, cut angles can select the curve parms, making the field wonderfully complicated. I used to have a booklet from Fox with some details, but can't find it; things like using crystals in series to get compensation, DC bias effects, good stuff.

GSKrasle
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Freelancer
Re: Vintage Time Delay Relay
GSKrasle   8/22/2014 1:45:59 PM
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And a Victorian-Size loop-filter!

antedeluvian
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Blogger
Re: Sorry to have missed it
antedeluvian   8/22/2014 1:27:00 PM
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mhrackin

 Anywhere in the airport area works well; if you wait, you may have to stay in Cleveland!

OOO Cleveland! Rock 'n Roll Hall of Fame

Wnderer
User Rank
CEO
Re: Vintage Time Delay Relay
Wnderer   8/22/2014 12:47:09 PM
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@ GSKrasle Could you build a PLL with the relay cycling as input, and take a multiplied output frequency?


Imagine how many hours that would take to lock. You have a VCO generating about a 1sec output that gets knocked down to 1 minute pulses to be compared to the signal from the relay. The phase error is then used to adjust the VCO frequency until the error is really small. You'd need lots of 1 minute pulses for the loop to do it's thing and sync the VCO to the relay.

mhrackin
User Rank
CEO
Re: Sorry to have missed it
mhrackin   8/22/2014 12:30:13 PM
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Hamfest site is hamvention.org.  Dates for 2015 are May 15-17. We are at the Quality Inn Suites. On Maxton Rd,  is a solid mile of hotels and restaurants near the airport and convention center.  Currently reserved for Fri-Sun but could modify easily.  Joe and his wife (same schedule as us for now) likely not interested in the tour as they have been going since before they rename the Hamvention!

mhrackin
User Rank
CEO
Re: 32.768kHz crystals
mhrackin   8/22/2014 12:23:09 PM
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Another interesting property of the 32K tuning forks: their frequency vs. temperature curve is a parabols, with the peak right at 37C!  Your wrist is the oven..... also explains why a (properly trimmed) watch will lose time when off your wrist.

Clive
User Rank
Rookie
Re: Sorry to have missed it
Clive "Max" Maxfield   8/22/2014 12:22:21 PM
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I think the IT guys have disabled links in comments due to spaming -- can you post the contact details for the hotel -- also what dates are the Hamfest? I was thinking that we could all drive up on Wed -- go on a museum tour (to be organized by Antedeluvian) on Thur -- and got to the Hamfest on Fri and Sat -- then drive back on Sun

mhrackin
User Rank
CEO
Re: Sorry to have missed it
mhrackin   8/22/2014 12:17:21 PM
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Talked to my friend Joe; he and his wife are going, and haven't missed ONE in at least 20 years!  They did warn that you need to make hotel reservations NOW as this is one of the major annual events at the convention center!  I made mine today, and there were few rooms left (at this hotel), and rates of course are high.  Anywhere in the airport area works well; if you wait, you may have to stay in Cleveland!

BTW, my wife is THRILLED at the idea!  Looking forward to the USAF museum etc.

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