I am a newly addicted fan. Reminds me of tinkering with my great-grandpa in the shed. He worked for Centel in Vegas and we'd rip apart things to see how they worked. I was (usually) good at putting it back together but when I couldn't, he'd finish the job or we'd use the parts to create something new. Love this channel!

This was delightful, like everything you all put out. 💚 you and 💜 watching you grow this channel and your content.

I recently retired from one of the successor companies of the old “Bell System” after close to 46 years. I was primarily in customer service and finance, but I did visit central offices over the course of my career. One of the things I learned from those visits, was that the ongoing support for older telephone plant depended so much on dedicated employees who did the job for so long that they could fix a problem blindfolded. You are one of those people who relishes the challenge of applying logic and a host of Bell System Practices to solve problems. Having a new home in the Connections Museum it’s great to see that legacy technologies are still alive and well1

Watched for a really awesome explanation of relays and stayed for the Trammell Starks/Weather Channel music at the end :p

I did a lot of work with residential furnace control design. As a young engineer I was unaware how much science went into modern relays. Long term use and reliability are critical for a commercial product. One example is the effects of the crossover plasma formed when the relay throws. it can disrupt other more sensitive components as well as determine the life of the relay. thank you for this series!

Great stuff guys. Where were you guys back in 1974 during my telephone hacking days, when I was struggling to make blue boxes and all kinds of gadgets to make the phone company my private playground. After high school in 1974, I went to DeVry tech for basic electronics. After that I tried to get a job in telephone electronics but no luck. A lifetime later i`m still in electronics, working in a circuit board assembly house doing final testing and component level diagnostics. I remember about 20 years ago, I received a note from my phone company telling me that they had shifted to 5ESS. And I thought, here is an opportunity to hack the system. LOL.

I loved this, Sarah, and couldn't wait to watch it the moment I saw the notification - thank you! I've always been fascinated by what is possible with relay logic, and I've always found the circuit examples from this era both fascinating and mind-bending at the same time. Similarly to phone switches, the cleverness that went into pinball games of the 50s and 60s shows a real art that has sadly been lost to time. I really appreciate you uploading the book to Internet Archive which I'm excited to start reading after I finish work today. Also, thank you to Astrid for the camera and cameo :-)

Probably most of your followers understand relays, but your presentation and personality make your video very enjoyable. Thanks for taking the time Sarah. I have an interest in the battery rooms and battery distribution panels and perhaps there applicable in today's solar field sometime of every chance could you show us the facilities there?

I like the use of Trammell Stark's Weather Channel music for the outro.

The improved script at the end, I wasn't ready. No change in tone or cadence just right into improve. 💀

I've only recently come across this channel and I am loving it! I'm fascinated with analog systems of all types, so this is right up my alley. I appreciate the understandable descriptions and explanations without 'dumbing it down'... not too much anyway. Thank you for helping preserve theses amazing old technologies!

Very informative video, loved the outtakes at the end. Keep up the great work!

My family has quite a lot of connection to the end of the step-relay switching office in the US, their last gasp of greatly improved reliability as they were already being retired, and their transfer to (mostly) South America. My father worked for GTE when I was a child and I work for Verizon today. These videos are a lot of fun.

Your book is convenient for me, because I also deal with the topic. This year I was able to save an old relay PBX from scrapping. I tried to understand its circuits and noted that the old relay logic is a foreign world, compared to modern electronics. The PBX is of all-relay type and has about 120 relays. The relays can contain up to 15 contacts and even in this small PBX at least 40 different relay coil variants are installed.

Literally using this video to teach the greenies how relays work this is awesome!!

That's a really good explanation of relays. I don't remember ever being confused with relays. But, a lot of my viewers ask me questions about the basic properties of relays that I use in my videos, so I spend a lot of time trying to figure out how to explain it to them.

I cannot wait for the next relay video. I was a switchman for southwestern bell in eldon mo. Local and toll SxS along with SxS cama was the offoce, or class 4 and 5. Excellent work in those days. Excellent video. Thank you so much. I gotta see if I can get a copy of that book.

I loved your look of delight when you pressed the button, and the light came on. You did a really great job explaining relays and demonstrating how they work.

Great video. Y'all are doing such an amazing job of not just preserving, but explaining this history. BTW Love the shirt!

I always enjoy your videos and the effort you put into them. Love the bloopers at the end. If only you had been my instructor some 50 years ago, lessons would have been so much easier.

As a fan of superannuated technologies, I would really love to come see the museum and watch the equipment operate in real time someday. Sarah, you do an amazing job of explaining the complexity of the various systems in understandable terms. Keep up the great work, and see you in the next video!

Well I'd never realized that relays originated as a signal relay for telegraphs! this was a very interesting video, thanks. Loved the outtake at the end, too. :D

Huh, the naming used in telephone switching is basically the same as the general naming convention in German: NO/Make is called "Schließer" = "closer", NC/Break is called "Öffner" = "opener". And I always get my brain in a knot because of this!

That was a beautiful video. I did Computer Science in my undergrad and I wish beginners logic was taught as well as you did it

That soldering iron makes my Weller 40 look like a toothpick.....

Such a great run down of the history of the relay (especially *why* it's called a relay, most people miss or skip this factoid when discussing the history of this magical little device!), along with a very accessible little discussion of how it works. The only thing I would add is an extension of the discussion to include a brief mention of the fact that the concept of the relay has evolved into the super complex strata of complex logic circuits that make up modern computing - perhaps the only thing that I find cooler than the magic that is a relay! Thanks for putting this together and out into the world! 🤓

I worked on 3ESS and 5ESS at the Western Electric NIW Works in Illinois from 1977 to 1983. The 3ESS used relays and reed grids for switching the calls. The 5ESS was all solid state and used gated diodes instead.

This one's been floating around in my feed I wasn't gonna watch it just yet, Glad I did. Fascinating. and as I am currently processing a relay Logic project myself this is probably one of the better explanations I've seen.

Very nicely explained. I worked for PT&T in San Rafael, CA on the frames and number groups of our Crossbar Number 5 office for a summer when I was in college. I really liked the environment. I hope to visit your museum someday.

To add to info and terminology for a different industry, trains. Where I work in the train industry would say a front and back contact. Front contact being open with the coil is de-energized and a back contact being closed when the coil in de-energized. A relay will have several contacts on one relay, some will be paired sharing a common between a front and back contact. Saying Battery is similar, but doesn't imply a specific voltage, it could be 12VDC or 24VDC, depending on the function and circuit. At 9:51 you can see what we would call a front back contact. You may find it interesting to know that most of NYC subway system operations via relay logic. There's a lot of relays as you can imagine.

I loooooove this video! Several times I went "OH!" as the light (heh heh) turned on. Now I kind of want a bunch of relays to play with because there's no way I'm going to retain this knowledge...

I got addicted to your videos a while back and think I've seen 90% of them so far. One thing you may want to bring up in a future video, based on the electromagnetic properties you may want to do a video on a step by step strowger switch as the principles behind energizing the relay goes to move the wiper arms up and across the contacts. Just my thoughts.

I've been enjoying your videos for a few weeks. If I lived in the US I'd totally get involved in the museum but I'm in the UK so I'll stick to heritage railways. However, I mostly came here to say awesome T-shirt! From a York (UK) based trans person.

What a great and funny to watch video! I think you did a great job on explaining the basics of a relais and some simple circuits. And I like the humorous style the explainations are given. The smile when the lamp turned on 10:46 😁 You really seem to love your job and that is great! And I also like the shirt! 😉 Keep up the great videos! 👍

Excellent, i love your videos. The animated circuit diagrams are inspired. I can really appreciate how much work and planning goes into something like this. It is here for education for all time (well as long as youtube content is preserved).

Houston! We have a problem 😕 Sarah sat for a whole video and didn't have to chase wiring problems etc. Well done Sarah! 😃

"Patreon: None :(" Where can I find you on Patreon? This video reminded me of those old educational videos that sometimes ran on TV, where they explained the miracles of technology. I think this would work great with a retro-Filter and 4:3 aspect ratio.

Alistair E. Ritchie, I never knew Dennis Ritchie's dad was such an illustrious employee ALSO of Bell Labs. Wowza.

Technology Connections vibes. ♥ Very good stuff, Sarah! :3

Thanks a lot for the great explanation! I come from the world of electrical/electronic engineering, so the telecom world conventions were pretty strange to me up till now. Like relays being switched on the ground rather than B+ / VCC side. 7:16 Big Iron! Relay logic is cool - Sam Battle (Look Mum No Computer) uses that a lot, haha! Again, big thank you for the tee :) 13:09 more #girlslikeus - the museum must be an awesome place, makes me wish I could join you, but I'm stuck up in a backwards country on the other side of the pond.

Thanks for this great explanation. It's clear you really enjoy sharing this info; and are a great teacher. Please keep it up! I work on modern generator controls with a combination of relay and PLC logic so this is still a very relevant thing to know!

First let me say I really enjoy watching your website. As a #5 Xbar tech 60 yrs ago for PT&T I still remember performing routines on Polar relays using a relay test set, I think it was called a 35A relay test set. Got one of those in your museum?. Looking forward to visiting "the museum" to see once again those magical switching systems. My office was ARCDCA11 for 10 yrs before leaving the state, I worked SXS, #5, Power room, TCXR, and maintained a #23 information office -

Very well done . Clear and informative.

Your videos are great, you explain things so clearly.

4:40 wow. You can think you know a lot at 47, but still only now realize where the name relay originated from 🤣. How did I miss that technology connection. And thanks for wearing that shirt ❤️🌈

Love it! I like the new format too! Although I’m glad you kept some of the fun and humour included. Great work!!! Happy Holidays!

Well done. Enjoyed visiting the yesterdays of relay logic. Also, thanks for the link to the book!

Transfer contacts are also commonly called Single Pole Double Throw.

For those wondering, yes, a phone switching system could, and several were, made entirely of relays -- North Electric and their CX line of all-relay switches are worth looking up. I imagine they worked incredibly well, but would have been, on a whole, more expensive at certain scales than other tech and as such weren't the best for all cases.

Fantastic lecture, thank you!

As someone who dabbled lightly in phone phreaking in my youth, I've been binging the videos on this channel. PS: Do you have any footage of the 48v power supply in the basement? I'd love to see Battery!

Glad to see you're at it again.

"Old timey nerds" - Note to self, do not drink when Sarah is presenting. Darn near choked.

/Great video. Also loved he T-shirt. You have my support. Christopher.

Great video as usual❤!!!

Great presentation! That color suits you btw.

Hey. Cool shirt. A+

Espectacular adoro este tipo de circuitos

I just found your channel and I am loving it. I spent my career with Pacific Telephone and it is so much fun learning about Panel switching, trouble cards in crossbar and everything else you cover. Your explanations are easy to understand. We had #5 crossbar offices and most were wire spring and one was flat spring. I recall flat spring relay crossbar offices had single sided trouble cards and wire spring offices had double sided cards. Am I recalling that correctly? Thank you!

Hey, great video. At 4:13 you refer to a transfer (or changeover) contact as DPST (double-pole single-throw). You misspoke and this should read SPDT (single-pole double-throw). It is the double-throw part which makes it a transfer (or changeover) contact. HTH.

Very good, thank you.

Relay awesome video! 👍

such a great video, and very good fundamentals for pinball nerds too

In the old days a delay relays were used .This was done by what was called an oil dash pot, that made the make or break slowed down buy fluid. Best regards Jack

I’m quite knowledgeable about relays since my homebrew AM transmitter uses quite a few to help minimise the damage to switches as well as this I have a British UAX13 10 subscriber rack and a ww2 wireless set 19 which use relays for lots of functions

I am trying to reconstruct some of the old indicator lamps that were used on communications equipment. They were constructed of a threaded brass tube, with a chrome bezel and white opaque glass dome insert. I am remembering these from many years ago and would really appreciate if you could share any close up images you might have of this kind of indicator. They were about 12 mm in diameter. Sail Hatan, Chris UK.

If y'all are interested in an in-depth exploration of relay circuit design and combinational logic, I highly suggest you search for "Clickety Clack Relay Computer" on youtube. Unfortunately the actual machine was never finished, but the builder did explain logic gates and the process of making a basic CPU with an ALU, cache, instruction set, and multiplexer circuitry just using relay logic. It's a great learning experience, and it's not too different from the circuitry you work with at the museum.

Wow amazing explain 👏 from #PowerLearningChannel

thanks for the video! love seeing how your production's been improving lately! trans rights!

These old machines are fascinating. Designed by the most brilliant humans in history. I know some of these old computers ran literally for decades without interruption. Also, ❤ your shirt. You’re wonderful and brave.

This harkens me back to changing 24-contact transfer relays, wiring nightmare in the back

I still use relays in some of my electronic projects. My home made thermostat has one to turn the heater on and off. (even though my room is usually warm enough that I don't need it)

Great stuff Sarah! Do you folks have a "mili-box" to set up the polar relays?

Have a nice Christmas!

Let me relay the message "trans rights!" Great video Sarah 😊

I spent a whole career as an electrical engineer and I still get confused over poles and throws but I'm 99% sure that you got that wrong at 4:15. A transfer contact (which I would call a change-over contact) is single pole double throw (SPDT). I's very non-intuitive but the poles are the number of circuits being controlled and the throws are the number of possible contacts being made by each pole. Actually it must be thirty years since I last used a relay so things might have changed.

The way they implemented the boolean logic of this is really interesting.

Beautiful video, as always. But can we please talk about that absolute gigantic soldering iron (at 7:10)…? 😂

the video was was great,

Thanks, this was pretty interesting! Yeah, relay logic was pretty much the earliest of digital circuitry, if I understand right.

Hi there. You mentioned something in a previous video about pay phone lines? I’d like to see more on that Is it still in the works?

I love those glasses!

Love your shirt. I wear mine a lot. I’ve always been mechanically inclined, so relays and relay logic just makes more sense to me than transistors and digital logic. Looking forward to this series on relays.

❤

Hey Sarah! Do you know of any other books on relay logic and also physical design of relays? I’ve seen a few BSTJ articles, but not a huge amount. I’m reading through that Keister, Richie book right now, but I know I’m gonna want more after I’m done 😊 it’s surprisingly hard to find books on relay logic!

Thanks for that, now I know how it got it's name. 🧐

4:25 Correct me if I'm wrong, but isn't that a single pole, single throw (or changeover) SPDT contact? Double Pole DPDT would be two of them.

KonradZuse liked your video on KZfaq ... I never knew why relays were called "relays"... thanks

Great vid as usual. I only recently discovered your channel and love it. From another trans woman here in Australia, Joni.

At 4:30, wouldn't the Transfer contact be a single-pole-double-throw (SPDT) arrangement? DPST would just be two independent make or break circuits.

:D Good morning, Sarah! :D

Guess I have another book to buy, lol. Thanx :->

I love relays like girls who know how to use them !😊

Thanks ladies, for another entertaining and informative instructional video.. With that said, I'd like to wish you all a happy holiday season, however you celebrate it, and I wish you all a safe, happy and prosperous new year.. Trans Rights ARE human rights.. 🏳️‍🌈 🧡

Relay arrangements and gates with transistors or chips are very similar.

All that fun with relays, but no inductive shock!! Isn’t that the best part??

The first Course when I was working for plessey telecom in the 70s on exchange construction was switch and rekey adjustment I would have difficulty with the job my eyesight is not what was when I was seventeen. Battery was the word that was used out in filed when I worked for the G.P.O. when I was Fault finding out in their network the test controls would tell use the is showing battery on the wrong leg off the Circuit

lamp turn on :D also it puts me in mind to ferrite core logic my second favorite logic system

I love lamp

Es werde Licht 😅❤