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Comment by Axien | Hacker News Reader

Am I the only one that is bothered that the finger stop (or whatever it is called) moves?

This is presumably a (physical) space-saving decision. The stop looks like it's right next to the 1. But dialing a digit requires moving the dial. So how can you dial 1 if the stop is adjacent and immovable? It looks like the answer for this small dial is that the stop moves only ~one tenth of a turn.

Hopefully then it does have a real physical stop---otherwise it'd be quite hard to dial correctly!

The thing which hit me was the (fast) speed at which the dial returns.

In a "real" rotary dial there's a governor which controls the speed of the return, thus setting the impulse rate so that the step-by-step switches in the exchange can follow.

Every phone tech back in the day would take considerable care to set the governor speed, and would instantly recognise when it was wrong.

Eh it's not wrong here though. There are always trade offs in a project like this.

Yeah that surprised me too. Is it there so that when the finger stop moves, it registers the number? I've only had a few rotary phones in my life, but I've never seen one where that doohickey (which I believe is the technical term) moves.

The moving finger stop was a feature of the Trimline dial phone.[1] It allows making the dial slightly smaller. On most dial phones, there's a large gap between the 1 and 0 holes. On Trimlines, and this new thing, there is no gap. Without that moving finger stop, you get a dial handset like this AT&T prototype: [2] That was called "the Schmoo".[3] Huge bulge in the middle of the handset.

The moving finger stop also appeared in 1960s versions of the Lineman's Test Set (the "butt set", usually hung from a tool belt), where the dial was on the back of the earpiece.

[1] https://en.wikipedia.org/wiki/Trimline_telephone

[2] https://www.bellsystemmemorial.com/images/dl/misc/schmoo.jpg

[3] https://www.bellsystemmemorial.com/telephones-trimline-artic...

etymologically, the term Schmoo or Shmoo (typically based on the characteristic shape) originates with the cartoon character popularized by Al Capp: https://en.wikipedia.org/wiki/Shmoo

A favorite example is the shape of a budding haploid yeast cell, known in the literature as a shmoo (though as that wikipedia page will indicate, there are a lot of other delightful schmoo/shmoo eponyms): https://web.archive.org/web/20071111122821/http://discoverma...

> Is it there so that when the finger stop moves, it registers the number?

No. Moving to the stop is just to wind up the mechanism up to a defined point. After being released the dial turns back at a defined speed, and creates a number short on-hook spikes, depending on far it has been wound up - the number to be dialed.

It's possible to quickly tap the hook to dial a number, too. It's easy for low numbers, but the dial helps the slow ones of us to tap exactly 9 clicks in the defined time to dial a 9.

No idea if that un-smartphone works exactly like the real thing.

If memory serves, the gap on the dial set the "interdial pause" which created a minimum gap between strings of digits, which gave sufficient time for the exchange equipment to switch to the next selector..

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