Panel (was Re: Touch Tone at 1964 World's Fair) [Telecom]

I never did understand how the panel switch worked. I guess it was a

>form of common control unlike SxS.

I have been fascinated by the panel switch, ever since being 'served' by one and noticing its quirks. I finally got to see one in action, BS-ing my way in on a night shift with a friendly tech.

It was really quite ingenious, and very high-tech for ca. 1920!

It can best be described as a 'panel' of open contacts with motor- driven contacts being raised-lowered to select the correct pair and then being 'tripped' to make the connection.

The method to control the thing was almost bass-ackwards from common thinking. The sender in the originating (intra or inter) office told the incoming and final frames when to stop advancing by way of an almost Rube-Goldberg revertive pulse method.

How did panel adapted to DTMF orignation dialing?

IIRC, tone receivers were simply retrofitted into the register- senders.

I assume this was the way, anyway. As I think back, I really can't recall anybody I knew who was 'served' by a panel office actually having Touch-Tone. I know that (then) 212-436 did not get Touch-Tone until it was cut to ESS in the early 70s. I remember it had a funky nonprecise tone plant until the cut, which would preclude DTMF.

I vaguely remember that 212-355 was panel and had the precise dial tone prior to it being cut, but I can't remember any actual DTMF sets on that office.

402-551 and 402-553 were panel into the 70s, and I seem to recall them having precise dial tone, but again, I can't remember any actual subscribers with Touch-Tone service on those offices.

Anybody know for sure if Ma Bell supported Touch-Tone on panel offices? (Carl, you listening in?) ;-)

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Wanna see a real Panel switch still installed and in working condition? And talk to technicians who maintain it? Go to Seattle, Washington and visit the Museum of Communications! This place is an excellent telephone museum housed on two floors of an operating Qwest central office (the museum gets their -48volts from the CO power plant!). It has a step switch, a couple crossbar switches and the panel switch. They all work and you can dial calls through them! And remember that odor a CO has? Enamel on the coil windings baking? They've got that, too! And lots of Teletype stuff, radio and television stuff, cord boards, TSPS positions, Repair Service desks and Test Boards. It's all there along with Pioneers who keep it working! Here's a link:

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Reply to
Al Gillis

I was in a meeting last summer two blockes from that place. Unfortunately, they are open a few hours one day each week. Didn't work for me.

Reply to
Sam Spade

That's a tough break! But try again, and plan several hours for a visit! It's an amazing place! And two blocks away??? That must have been at or near the Boeing Museum of Flight! Another excellent museum!

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should wet your whistle!

Reply to
Al Gillis

The meeting was at a Boeing facility between the two museums. But, we fared better at the Boeing Museum. Because Boeing hosted the meeting we had lunch one day in a private dining room at the museum follwed by 90 minutes to tour the museum.

I had been there previously in any case.

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