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Nice hair

What siren was that in the beginning

Could you talk about what happens to the equipment when it loses power? Are all calls dropped when that huge fuse blows - and again when the switch is flipped after replacement? Do they disconnect when it does a "reset" on powerup? Does it just keep working in the last-known state? Are there redundant power paths to every piece of equipment to reduce the impact of blown upstream fuses like on modern servers?

The catch with the Chrysler Air Raid Siren- Receiving the signal didn't directly activate the siren. It told a guy that he had to go up, start the motor, and manually engage and disengage the clutch to the siren rotor mechanism. One of the top 10 jobs I'd never want, sitting on a roof/tower warning the world that it's ending without being able to hide, yourself!

distracting transmission ruins the film

Why motor-generators rather than mercury arc rectifiers? There are far less moving parts on a mercury arc rectifier

Thanks for sharing your technical knowledge on how the bell system worked with the CD system. As a kid I remember the "duck and cover" drills a school.

Quick note on the grasshopper fuse, I have a hand blown one by Sarah. HA! Love that museum.

I do wonder, why keep the extra wires? Do they serve a use just being there? Purely for the look?

❤ Beautiful!

Why did they choose 48 volt

@10:57 it is suggested that DMS10 would have interfaced with a TTY (or teletype) in the 1970s. The Nortel DMS10 was not manufactured until mid 1980s and typically had a DEC VT100 as serial interface device for switch maintenance and operations.

An interesting, well presented video. Thank you. I love all that old tech and have no time for modern digital stuff. I much prefer my old tube (valve) electronics to all that silicon micro-chippery. Cheers from across the Pond!

I have an old ringer in the basement. I gotta go get it now make a video on it! ❤

Natural gas backup? NOT. Ma. Bell going all out VoIP, where customers need the battery

First I would analyze what the goo is. Mercury wetted relays normally don't leak anything. I would consider warming the relays and put them in a vacuum to encourage the goo to come out in a controlled way. The goo may be uncured potting material.

This looks so cool!

BackEMF could drive current upstream, but that would be extremely rare (or the grid is down, which is quite dangerous). The more likely scenario is that the Back EMF will increase heat in the windings and eventually lead to the system melting/catching fire. This is also why in AC undercurrent situations you have a time window where components will automatically sever themselves from the power grid. Running at too low a voltage will cause back EMF and it’s only a mount of time before components exceed their temperature rating (this is why power providers are forced to choose rolling blackouts over running with sagging voltages)

I love your look! Like a stereotypical happy gay person. Combined with how you talk, you seem fun to hang out with!

If I had only grew up in the Seattle area, I know I would probably be at the museum today revamping equipment. While not quite as old as most of this equipment here I have been working on it's slowly dwindling vestiges since the early-1990s. Unfortunately, I'll have to be content to visit every few years when I'm in the area on work.

This is not telco, but it’s all I got. The Nevada unemployment office had a big diesel backup generator for their computers. There was a big tray of lead-acid starting batteries on the floor at its side. Every week a maintenance guy would stand off to the side (in view of the tray) and start up the generator. This one week for some reason he stood in front of the the generator control panel in the shadow of the generator. The batteries exploded, spraying acid all over everything, but as he was in the shadow, he escaped harm. You could see the stains in the generator’s paint where the acid ran down. The OSHA Website used to (but no longer) describe fatal injuries as object lessons. One was a L-A battery cart used to start cars with dead batteries. One day it exploded, killing the operator standing adjacent. Moral: Never stand in line with starting batteries.

If they had no batteries in phones instead just put them in one building then why do we have batteries in phones today?

7:02 is that m2009 hooked up to anything?

I've seen the battery room with its row upon row of clear-case batteries at the old telephone exchange in my town. I've also seen the generator they had for standby power. They used to run it for some time (I don't know exactly how long, but I'd guess at least an hour) each Monday, just to keep the oil flowing and the battery charged. I seem to recall one night when the power went out for a while and I stepped outside the house to look at the darkened town, and it was so quiet that I could hear the generator at the exchange rumbling away, even from around 3-4 blocks away in a more or less diagonal direction. I recall being told that the generator wasn't actually designed to be used for emergency backup, because it tended to throw oil around until it warmed up properly and the seals heated up and closed the gaps properly. It was intended for continuous usage in a situation where the grid wasn't available. I presume the exchange building still has a backup generator, but it would be supplying the Internet equipment and the mobile/cell phone tower. I'm pretty sure the old generator was retired years ago and they have a replacement. And now I'm remembering the time that around half of the distribution equipment in the exchange went out. You could pick up a phone and stand there hearing nothing while the uniselector desperately attempted to find an available path. I think it was out for around 30 minutes until whatever the problem was (I never found out any more) was located and fixed. You could occasionally get a dial tone, but it wasn't easy and you weren't guaranteed to be able to connect. By the way, the first fully automatic telephone exchange was designed by Almon Strowger, which is why the step-by-step switch was also called a Strowger Switch. He designed it using cut-out paper pieces. According to the story, Strowger, an undertaker, was convinced that the manual telephone operator, who was related to his only rival in town, was deliberately directing all calls for "The Undertaker" to the rival company instead of evenly dividing them between the two companies as was the policy. Strowger was motivated by this to work out a way for subscribers to dial the number themselves. As I understand it, Strowger's exchange required 4 wires, with the 2 extra wires being used for number signalling, but later developments allowed the numbers to be conveyed through just two wires along with ring current and sound/voice.

This is a great presentation. I’m sure it will generate lots of comments and stories. I have one for the group. In 1967 I was in the Army assigned as an SP4 Dial Central Office Repairman at Ft. Benning, Georgia. Ft. Benning is now Ft. Moore. General Benning fought on the losing side of the Civil War. My job was night and weekend inside plant man for the post. I watched over the four telephone exchanges at the fort during non-working hours. Sounds awful, but it was really pretty neat. I got to work on equipment. The Army Dial Central Office Repairmen on regular duty hours cut the grass while civilian employees worked on equipment. But on to the story - I had just come into the Main Post central office to start my 8:00 AM Saturday to 8:00AM Sunday shift. I took off my jacket, stretched my arms, then the lights went out, followed by the sound of the motor-generator winding down. We are on the batteries alone and we had no backup power source. I ran to cut the switches to the motor-generator so it wouldn’t try to suddenly start up before I had time to figure out what as going on. I called the Wire Chief to report what was going on then called the Post Engineers to find out what happened to my power. The power was off to perform scheduled power line upgrade. Scheduled with who? Would have been good to know in advance. Our battery was 20 years old and the end cells cut in very soon after the power went down. I won’t make you sit through the next three hours while I watched the volt meter slowly wind down. It was tense. But the power did come back on. I cranked the control for the voltage of the motor-generator down before restarting it. I was afraid the exchange load plus the load of recharging the battery might blow the big fuse like the ones you saw in this presentation. We didn’t have a spare for that either. Hey, don’t look at me, I was just a lowly E-4. Planning and decisions were above my pay grade. Anyway, the motor-generator did come back on. I put it on-line and spent the rest of the day slowly cranking the voltage back up to the normal level. Whew.

I love this channel. The poem voltage regulator system was later used in cars to keep the output constant regardless of the engine speed. I didn’t know this idea was invented so early. And the speed regulator is ingenious. This same idea was later used in battery tape recorder motors before electronic control came about.

So I’m not sure it’s been explained but how does a long distance call from city a to city b work where there are no direct trunks between the two and the call has to be routed through an office in city c?

Glad you didn't write it in python, but everything is moving in a rust direction.

I find it funny how everyone is the good guy in this. Why would you need a telephone after you just destroyed the world? Will the IRS get a phone so it can collect taxes? You need a phone to do what? Regain control over the people, the food supply, the media so you can blame someone and get the whole process started again. The people who make these plans belong in prison. The world would be a better place if Bell never existed.

I’ve done some accidental welding with -48. That is a very bright flash that I don’t particularly want to see again.

On the vid thumbnail why is there a cardboard cutout of person

Great job! Background info on those 'world-ending' sirens that I did not know. The weekly Friday test would wake me up from my afternoon nap in the mid-60s. A sub-optimal way to wake up as a little one.

@9:45 the coils you point to don't sense "back EMF", they just sense overall current going in either direction and cause the breaker to open in an overcurrent event.

I live right down the road from the local fire station that has the city's air raid siren on top of it. Its also used as a alarm to call firemen to the station whenever there's a fire. Every time that thing goes off, I just about panic. I do NOT like the sound of air raid sirens!

This seems like a super interesting topic and video. I'm sorry though, the bright neon green hair is too distracting for me. Good luck to you.

When I was in the USAF, you could get the base operator to place an Autovon call back home for you at night when there was low traffic. We were sure not to do it too often, which might have raised flags. You had to have after-hours access to a military phone, of course, such as at a MARS station.

I dont like sweater she has on @ 1:07

Gotta make some dummy battery boxes to hide the SMPS bodges, for aesthetic purposes. Of course, these battery blanks need to be labeled as part of the "NeverReady" brand 🤣

Every 2nd Tuesday of the month ❤ … Hey from SF🌈

White Alice was a 'Over the horizon' Microwave system. It refracted the signals across mountain tops to deflect the signal downward, This both extended the range, and improved coverage past the mountain. This required a much higher RF level than point to point microwave links. This is also why the antennas were so big. I was a RF Engineer in the US Amy in the '70s at Ft Greely. We used White Alice for both military and civilian phone service, as well as to feed the AFN radio network and multiple current loop teletype circuits. The audio was exceptionally clear. I could call home to Ohio and get better service than a local cal since it was microwave all the way to that city's CO. Greely was used for the Lend Lease program during WWII as an Army Airfield to supply Russia with planes and other warmaterials.

With the advent of the safety mechanism, scrugmug was all but eliminated.

I love this! subbed!!

As an electrical engineer and master electrician in New York City, it's pretty funny seeing some of these switch gear in a museum, yet. I still see them in major Telecom COs to this day.

If i went to work only repairing the past.... where wood we bee.

Today with FiOS you need LiON batteries at your house to use it...

I love coming across your page! I. found one of these rooms in an old hospital that was abandoned in 2019. They had a newer telephony room that ran off of the newer grid, but It was wild seeing this and learning how it worked!

Yep. I saw firsthand the MASSIVE detroit diesel gensets used to power the Orlando FL telephone system. It's on Robinson Ave. If you care to look it up. They are spectacular!

Well done . Quite an achievement .

Not to be confused with 'Tip and Ring'... can still remember getting zapped with ringing voltage working on old 1A2 equipment... guess that makes me old school...

I guess you have to go and do this in reverse when you leave for the day..