"Calibrating" Dials?

[HobieSport]

I've read of a seller of very high quality refurbished phones that he "calibrates" the dials with a electronic phone analyzer" to make sure each number is sending the right signal.  Any idea what that's all about?  Uh oh.  I just set up for anal jokes.

But seriously, I need a crash course in basic electrical engineering related to the workings of these old phones.  Any good articles on the internet?  Who on the forum knows all the workings of the dial phones electronically? Thanks,  -Matt

[bingster]

I'm not an expert on dials, but I can tell you what I do know.  The purpose of a dial is to interrupt in regular intervals, the flow of electricity coming through the line.  The central office equipment detects these regular interruptions and interprets them as "numbers." 

The calibration process is nothing more than making sure the dial sends these interruptions or pulses at a specific rate of speed.  Many people make the calibration process out as something mystifying, but it's really nothing more than speed adjustment.

[HobieSport]

Thanks Bingster.  So...how do you adjust the speed and test if the speed is correct?  Maybe a thread on that here somewhere...

I'm most talking mostly about WE 5H dials.

[bingster]

Adjusting the speed is easy with the adjusting screw in the governor, BUT... determining if that speed is correct is the kicker.  It takes extra, very job-specific tools, to do that. 

[benhutcherson]

I've been working on a set-up which uses the microphone port of a computer sound card to test dialing. The basic idea is that the dial contacts are connected as a microphone, and each pulse generates a "pop" in the sound file. It's then possible to look at the waveform of the sound file, and get an idea of how the dial is operating. Not only do you get the peak-to-peak spacing, but also an idea of how the contacts are opening and closing.

I have the basic concept working, but need to iron out some details to make it practical. I'll write it up on here when I get everything working well.

A properly operating dial should run at 10 pulses per second.

[HobieSport]

Sounds great Ben!  Looking forward to hearing/learning how it works.  A simple inexpensive way of testing dial speed using the computer would be very welcome indeed.   -Matt

[BDM]

Somewhere in my many books on telephones. It states with the system(20 years ago now), 9 to 12 pulses per second is standard. There is a window of course. If I can dig that info up, I'll post it. Mark Ben and myself are going to try and put together a little dial tutorial post about W.E & A.E. dials. When we do, I'll stick it at the top. Notice I've stuck other subjects at the top. I believe these are important to seasoned and beginner collectors. Please post anything info you gents have in those threads.

[Dennis Markham]

Brian, sometimes you have referred to me (I think you mean me) as Mark.  Which may be confusing me with Mark Stevens.  But it may be because of my last name.  Throughout my life, even friends I've known for years have called me Mark by accident.  I guess my parents should have named me Mark Markham.  Maybe you meant Mark Stevens.  I'm not offended in any way, just for clarification.

Dennis

[BDM]

Yeah, I do. Mark, Markham...... Sorry. I meant Dennis.

[HobieSport]

So is there a simple way to calibrate a dial without fancy equipment?  -Matt

[BDM]

So is there a simple way to calibrate a dial without fancy equipment?  -Matt

Yup, your ears, and if it works

[bingster]

There's another problem that can affect the dial, and it's the fact that dials do get dirty.  That can cause not only an off-speed problem, but it can cause the dial to spin at the correct speed at the beginning of it's return, but slow down toward the end of it's return.  That sort of variable speed can't be corrected by adjusting the governor.

[BDM]

Nope, sure can't. You bring up a good point about dial cleaning. Though, it must be done with care and patience when taking one completely apart. Or it will become something other than a dial

[Mark Stevens]

So is there a simple way to calibrate a dial without fancy equipment?  -Matt

Yup, your ears, and if it works

Dial calibration is one of those buzz-words that the high volume phone restoration guys use to help them get $300 for a model 302.  They want you to think that perking up an old phone involves some sort of voodoo that only they can perform. Just MHO. 

[BDM]

So is there a simple way to calibrate a dial without fancy equipment?  -Matt

Yup, your ears, and if it works

Dial calibration is one of those buzz-words that the high volume phone restoration guys use to help them get $300 for a model 302.  They want you to think that perking up an old phone involves some sort of voodoo that only they can perform. Just MHO. 

I couldn't begin to tell you how many radio collectors/restorers are like this!