Author Topic: Does dial impulse short tip-to-ring? (Galion with AE dial)  (Read 315 times)

Offline bnaOldPhones

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Does dial impulse short tip-to-ring? (Galion with AE dial)
« on: March 25, 2017, 12:08:11 PM »
Or should it short tip to the far side ("R") of the induction coil primary?

This is in reference to the usual "North Galion with AE dial" circuit diagram, http://www.classicrotaryphones.com/wd_galion_big.jpg.  This looks to me like, when the dial is off-normal, L1/ring is connected to the middle shunt spring, which is connected through the bottom shunt spring and the built-in strap on the dial to the "stationary" (upper in the diagram) impulse contact.  Since the "movable" (bottom in the diagram) impulse contact is connected to L2/tip, a dial impulse would directly short tip-to-ring.

Is this correct, or should the middle shunt spring be connected to "R" on the coil, thus truly shorting the receiver and transmitter back to their common ground?  This would mean that a dial impulse "make" would connect tip-to-ring across the coil primary.

Offline dsk

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Re: Does dial impulse short tip-to-ring? (Galion with AE dial)
« Reply #1 on: March 25, 2017, 12:58:37 PM »
According to the diagram it shorts the line, this was common on the earliest phones in many parts of the world, German phones did that as long as they had rotaries.  From some time in the nineteen-thirties many makers did similar to what you suggest, just leaves the primary winding un-shorted.  I do not know why, but sometimes a dialgizmo works better with the line shorted by the dial.

dsk

I have even got a regular New York number :-) 646 570 1796

Offline bnaOldPhones

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Re: Does dial impulse short tip-to-ring? (Galion with AE dial)
« Reply #2 on: March 25, 2017, 03:09:52 PM »
Thanks for the info, dsk.   Actually my post was 180 degrees off, dial windup shorts the line, and dial impulse (intermittently) breaks the short.  But you knew what I meant.  :)

I think when I do my build (I'm building a Galion starting with an empty case and parts!) I'll hook impulse to "R" and see if it works.  If I don't like it I'll move it to "ring" and try that.

Offline dsk

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Re: Does dial impulse short tip-to-ring? (Galion with AE dial)
« Reply #3 on: March 25, 2017, 03:25:31 PM »
It looks right to put the R wire to the R terminal, but I do not think it really matters.  I had to look at rotaries made in Norway, and actually the last rotary, made from 1967 shorted the line when the dial was out of rest position, while most phones made after 1934 had a similar diagram to what you want to make.  Not easy to know to do this or that, so do what you feel for, it can not go wrong, and it is easy to change whenever you want.   ;D
dsk

I have even got a regular New York number :-) 646 570 1796

Offline bnaOldPhones

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Re: Does dial impulse short tip-to-ring? (Galion with AE dial)
« Reply #4 on: April 17, 2017, 09:35:33 AM »
So, an update.  I hooked the "red" wire off the dial to R, instead of L1.  Most things worked ok, but the "dial hold" feature of my DialGizmo worked only sometimes.  I also noticed that when the dial went off-normal, I could still hear a faint dial tone in the receiver.  (Strange ...)

I switched it to L1, and now dial-hold works, and the receiver is completely silent when the dial goes off-normal.  There are some loud receiver clicks when it goes off-hook, and at the beginning and end of dial travel, but I'm going to build a little varistor to take care of that when the parts arrive in a few days.