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Old 1st Sep 2018, 10:33 am   #1
mickyfinn
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Default Question about dial contacts

Know nothing about telephones.I bought a 1960s Seeburg home entertainment unit thats basically a jukebox that plays 33.3 albums.It originally used a phone dial selector unit. Didnt get this with the jukebox but managed to build one using a modernish clear plastic phone dial. Turns out this dial is NC, I need a dial that at rest is open. Is an older type dial likely to be what I need? From pictures of an original it looks like a black standard phone dial, can't see Seeburg building their own if it was just a standard item .If they are available could someone please tell me how to word a "wanted" ad on this forum.

Many thanks
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Old 1st Sep 2018, 12:44 pm   #2
Dave Moll
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Default Re: Question about dial contacts

If the dial needs to be open when at rest, could you use the dial-off-normal (DON) contacts in series with the dialing contacts. These are open when the dial is at rest and closed when the dial is moved from its rest position. One pair of DON contacts usually shares a terminal with one side of the dialling contacts. You may, however, get one more "connect" than the number you dial, as the first will be as you turn the dial, followed by one after each disconnect as the dial pulses.

As telephones used loop disconnect to pulse the steppers at the exchange, I'm not aware of any that work the other way round.
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Old 1st Sep 2018, 12:49 pm   #3
dagskarlsen
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Default Re: Question about dial contacts

Regular telephone dials has always been NC, Kellogg had an intercom system with NO contacts, never seen one. Should be possible to adjust yours, or just connect it differently.
Usually a rotary dial has at least 2 set of contacts, the pulsing one, and one or more contacts shorting out the clicking sound from the receiver. using both contact sets you may close the contact when the dial leaves the rest position, and the pulse the number of breaks referring to the number of the dial. This will result in one more pulse than you actually want. That may be solved by moving/adjusting the shorting contact set the shorting to short before the last break, or maybe just adjusting the pulse brakes to be NO.

A picture of the back side of the dial may help us giving you a better answer.

The type I dial I know best are on picture: https://goo.gl/ejXdTb

dsk

Last edited by dagskarlsen; 1st Sep 2018 at 1:17 pm. Reason: spelling
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Old 1st Sep 2018, 12:50 pm   #4
mickyfinn
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Default Re: Question about dial contacts

Thanks Dave,I did try several wires(theres maybe 10 or more)but nothing was suitable.I can only think that Seeburg must have used some method of reversing the state.Unless the USA dials were different?Was hoping to be able to use something earlier maybe in black that would have suited the era of the machine better.A friend has made a little circuit board using a transistor that does the job for now.
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Old 1st Sep 2018, 12:51 pm   #5
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Default Re: Question about dial contacts

Will get a pic.
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Old 1st Sep 2018, 1:24 pm   #6
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Default Re: Question about dial contacts

Just use a relay to "invert" the pulses from the nc dial.
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Old 1st Sep 2018, 2:22 pm   #7
Dave Moll
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Default Re: Question about dial contacts

Quote:
Originally Posted by mickyfinn View Post
Thanks Dave,I did try several wires(theres maybe 10 or more)but nothing was suitable.
A standard GPO dial has a mere five terminals, two are the pulsing contacts, of which one is common with one pair of DON contacts, with a second pair of DON contacts isolated from the other three terminals. This may be a better starting point than something with a large number of connections whose functions are unknown.

Quote:
Originally Posted by mickyfinn View Post
I can only think that Seeburg must have used some method of reversing the state.
As suggested by rambo1152, using the disconnects to operate (or rather release) a relay would be the simplest way to achieve this. This could of course be done electronically if you prefer, as it is in effect a NOT gate.
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Old 1st Sep 2018, 2:27 pm   #8
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Default Re: Question about dial contacts

Just as an aside (I know nothing about jukeboxes), standard US telephone dials also have normally-closed impulse (pulsing) contacts. As do French,German and Danixh dials (to name others that I have worked on).
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Old 1st Sep 2018, 3:25 pm   #9
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Default Re: Question about dial contacts

Pic as requested.
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Old 1st Sep 2018, 3:43 pm   #10
TonyDuell
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Default Re: Question about dial contacts

That looks like a standard UK telephone dial. The Blue and Slate (grey) wires are an independant off-normal contact, open when the dial is at rest and closed as soon as you move the dial from the normal (rest) position.

Orange and Pink are the normally closed impulse contacts which open the appropriate number of times as the dial returns to the 'normal' position.

Pink and Brown are another normally-open off-normal contact (open when the dial is at rest, closed when you move it off the normal position). Of course this shares a terminal with the the impulse contacts.

What happens if you use the orange and brown wires? That would be normally open, close when you turn the dial, then open the appropriate number of times as the dial runs back and finally open (and stay open) when the dial is back to the normal position.

Incidentally, I learnt to remember the order of those wires on the dial terminals by :

Bill (Blue)
Said (Slate)
B****r (Brown)
[the]
Post (Pink)
Office (Orange)
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Old 1st Sep 2018, 4:08 pm   #11
Dave Moll
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Default Re: Question about dial contacts

I assume the asterisks represent "othe".
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Old 1st Sep 2018, 4:09 pm   #12
mickyfinn
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Default Re: Question about dial contacts

LOL!
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Old 1st Sep 2018, 9:47 pm   #13
dagskarlsen
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Default Re: Question about dial contacts

That is a good reliable dial, I guess you need a reset signal to, since it only will add more pulses for each time you dial a new digit.

If you glue (melt glue) on a litle plastic on the blue cam wheel so the yellow handle pushes the contacts open you will get your pulses with correct number. The off rest position contacts could be a reset function?
dsk
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Old 3rd Sep 2018, 8:34 am   #14
bobsterkent
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Default Re: Question about dial contacts

Quote:
Incidentally, I learnt to remember the order of those wires on the dial terminals by :

Bill (Blue)
Said (Slate)
B****r (Brown)
[the]
Post (Pink)
Office (Orange)
That's exactly how I was taught it!
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