CuriousMarc - 2024-11-08
With great difficulty, we repair our Patron-donated HP 115BR divider and clock, an instrument that was once used to synchronize all of the world's atomic clocks. It requires a bit of a fight, but in the end, we are rewarded with the most steampunk atomic clock ever! Link to the HP 115BR Manual: https://bama.edebris.com/download/hp/115br/HP_115BR_frequency_divider_and_clock_op_service_manual_1967.pdf Stuff that supports the channel: - Support us on Patreon: https://www.patreon.com/curiousmarc - Amazon links for the tools I use in the lab: https://www.curiousmarc.com/amazon-links - Channel merch on Fourthwall: https://curiousmarc-shop.fourthwall.com - Legacy channel merch on Teespring (I don't have everything transferred to Fourthwall yet): https://teespring.com/stores/curiousmarcs-store "Elevator Music" Credit: Crinoline Dreams by Kevin MacLeod Our lovely sponsors - PCBWay: fast turn PCBs, https://www.pcbway.com - Electro-Rent: https://www.electrorent.com - Keysight: test instruments: https://www.keysight.com - Samtec: connectors: https://www.samtec.com - R&D Microwaves: https://rdmicrowaves.com Get more technical info on the companion site: https://www.curiousmarc.com Contact info: https://www.youtube.com/curiousmarc/about
Bad ancient tantalums?
Who would have thought!
Tantalizing repair.
I remember seeing an Amiga (late 80s/early 90s computer) for sale on Ebay where the vendor advertised that they had replaced ALL the capacitors as a matter of course!
Good old tantrum capacitors!
@@zh84 Sadly, this seems to be commonplace. Inevitably, it introduces new problems, as Adrian's Digital Basement found recently. He replaced the caps on a Mac SE/30 motherboard and in doing so accidentally bridged a 5V signal line to the 12V power rail. I've seen all sorts of other problems caused by recapping - reverse polarity, massively wrong value, under voltage spec etc.
Hardware from this era was beautiful. Really enjoying this series.
New Curious Marc videos showing up in my feed always make my day!
"Miracle dividers" - I couldn't agree more. That 4 transistor divider circuit is sheer analogue genius. Thank you for another very watchable episode.
You know, that generation of engineers continues to astound me with what they could do with so few options. How one can create a sort of “minimalist complexity” still looks a bit like magic to me, wizardry I say.
We often don't appreciate how good we have it.
Marc: “This is going to be interesting.”
Yes. Yes it is. 👍
If I drink enough, my vision phases out the potato vision.
You were just early. Now it's up to 2160p.
Only with alcohol from potatoes
I watch everything on my phone, I barely noticed the potato vision.
@benjaminhanke79 I takes YouTube a while to render the higher res. If you just watched all was finished. NeillABliss was a bit hasty commenting on the quality.
@@bennylloyd-willner9667 Some of the video was shot out of focus with a comment over the top apologising for the "potato vision" (e.g. 11:18) - nothing to do with YouTube's processing.
That tripler circuit (6:40) is at once crude and elegant: driving the thing so hard it distorts wildly then using the fact that a single ended circuit will have dominant odd order harmonics and picking off the third. So clever.
Great video. I love your explanations, demos and your test equipment. Quite a project!
Thanks! I am feasting on short clips from your old NASA videos too to look for Apollo comms equipment, I hope you don't mind...
In the late 60s, I worked at a NASA STADAN station at Winkfield UK. We had a visit from the NASA calibration team. They flew around the world calibrating the test equipment. They also carried an atomic clock to check each station's clock.
I have absolutely no justification but I want one after seeing this video. The engineering is gorgeous, and that display is a work of art.
Thanks for the continued awesome videos!
I must be weird too : I enjoyed watching the various frequencies on the scope! 😮
… and a blurry schematic too!😂
Dr, you have no idea how much I like the content on your channel; The analysis, the theory he uses makes his video super interesting. I thank you infinitely for all your effort and time in preparing each video. A cordial hug from Mexico
As a 60 year old mechanical engineer watching this, please, please, please clean the mechanical clock mechanism as per the service manual. Do it before it is too late. The tight tolerances of the bearings and the gearing are being abnormally worn every time you start the motor. The clue that it needs to be cleaned is that you must give the motor a very strong torque to start it spinning. You should be able to start the motor by a simple twist of the knurled handle between your thumb and index. Also HP would never have let such a noisy mechanism out the door. It should be whisper quiet.
We know. Clock is clean. There is a bad bearing in the mechanism. It's very difficult to change, haven't done it yet.
Thanks Marc for doing these videos, like everyone's comments those HP engineers and manufacturing infrastructure were next level.
Amazing bit of kit, transitional technologies are just so fascinating... love the germanium transistor mounts. Also, yours is the only channel which makes me want a noise blanker in the audio path
Nice work loop circuits always gave me a fit when I was working in electronics. Thanks for the video Marc.
5:40am & curious Marc. Breakfast and a cup of tea….perfect end to the week
This is a great example of why I so admire early HP engineering. Just Incredible stuff, from the year I was BORN! Remember, engineers used slide rules in those days! AND their BRAINS! 👍
They use their brains today as well, just a different age.
@@henrivanbemmel Sure, but today we use so many computer assisted design tools. You have to admit, engineers did some amazing things with very little.
@Runco990 Of course, but then with these modern design tools folks today do amazing things on top of them. Back in the day, they did the best they could with precision mechanicals. No one is doing that today, because it's hugely inefficient. I'll bet if the folks from those days had today's equipment, they'd use it too. Just as almost no one today, given competence, would choose a typewriter over a word processor.
@@henrivanbemmel Maybe you mis-understood my comment. It's amazing how clever engineers were back when they had such few tools to solve problems that may have seemed impossible. Today, we take assistive tools for granted because anyone can have access to them and use them. What seems easy to us today, must have been an unbelievable challenge when you had to be first ever to do it.
@@Runco990 Indeed, but today's tools remove much of the scut work allowing today's scientists, who are every bit as smart, move things ahead in situations that are far more abstract. When something has not been done before its always hard as it requires imagination both in theory and experimental apparatus choice and augmentation. When doing original discovery often the instrument of the day is being pushed near its maximum and signal must be teased from noise. It is effectively the same issue at most times in history. Finding the parallax of a star in 1838 would be then as challenging as using today's telescopes to measure the properties of an exoplanet's atmosphere. In both cases the equipment of the day is being pushed near its limits and the resulting noisy must be carefully reduced.
I feel it's a matter of degree. Millikan's oil drop experimental was a masterful piece of work in 1909, today it is done some high schools, but it is no longer discovery as we no longer need the imagination and the apparatus is pre-designed.
I agree though with the history aspect. Seeing such elegant equipment is like other historical devices of influence such as decent padlocks or a steam engine is amazing and I'm a fan.
A few good beers and 40min of HP goodness repair. That was a nice evening. Thank Marc.
I'm a software engineer who considered being an electrical engineer when I was in high school in the 1970's. I like your methodical approach to debugging the various problems without making unwarranted assumptions. It is similar to how I debug a misbehaving program or OS kernel crash. It's a shame that so few professionals in our respective fields seem to have good debugging skills.
25:50 That's wild, the tripler is happily working as a quadrupler instead, thanks to its asymmetric single-transistor design evidently also generating plenty of even harmonics and not just the odd harmonics you'd get from nicely symmetrical clipping.
Oh, good catch! That's exactly what's happening.
Merci Marc, another great video.
Another great video. Please keep making them!
This is super! A lot of creative engineering from 196s
"If you follow the channel?" Of course I follow the channel!
Perfect Friday morning content!
This device appeared in the recent Nova on PBS. Just for a few frames, but it was so obvious after having seen Part 1. Will try to get a link and offset for y'all.
Just watched it. Great episode on how quantum mechanics affects everyday life: https://www.pbs.org/wgbh/nova/video/decoding-the-universe-quantum/ . The HP 115BR appears briefly at 17:35, followed by the HP 5061A Caesium clock equipped with the later integrated Patek Phillipe divider and clock. Awesome science documentary, they are right up there with Veritasium. Or is it the other way around?
@@CuriousMarc Video not available for german users :(
Perhaps it's available to international viewers via YouTube: https://youtu.be/t06aTX9jM34?si=98Ojo9C3zVJAuWLl&t=1061
Suspect the tantalums! Great job Marc. Love the point-to-point electronics, so easy to work on. That synchro motor is noisy... perhaps some Hamnmond tone generator oil is needed? I just bought some Kroil Microil, looks like the exact same thing... the mechanics sound a lot like a Hammond organ that wants oil!
Syncrho motor is fine, but there is a bad bearing in the clock mechanism. Replacing it is a bear though, you have to take all the gears out, so I haven't done that yet.
You really do have the best toys.
At Curious Mark's™ "We've Upped Our Quality. Now, Up Yours"...
37:56 Interesting how they fastened the seatbelts! However, it looks like the equipment was travelling economy class. That's a bit of an insult to H.P. equipment. Should be first class all the way!
At least the cabin attendants gave them blankets and pillows.
What's the purpose of centiseconds markings on the wheel? For use as timestamp on short-exposure photos?
Another great one.
11:31 “Use your imagination to see this clearly” this would make an engineers life so much easier… 😂
Are the start switches duplicated on the outside? Or do you have to remove the unit from the rack and open it to press buttons and spin the motor every time you want to start it
And they strapped it in a seat on the plane!😂 Well, it would be a more gentle flight than if it were bolted to the floor.
Wow, that world tour to synchronize clocks sounds fascinating, it's History, significance and all. Is there a documentary or an interesting resource on the subject?
So, you have to remove the top to start the oscillators and motor manually every time, or can it be done without ?
Remove the top and start the oscillators. Plus unscrew the plate over the wheels and readjust the time. Plus hook a scope to WWV and adjust the tick. Make a prayer to the Gods of horology (don't forget that step). It's a whole ceremony to get this clock restarted.
The "old" HP hardware is just beautifully designed and constructed, much nicer than the plastic stuff that's cranked out these days. It is somewhat odd that one needs to "kickstart" the device (open the rack?) every time?
3:06 it's like electronic surgery.. Nurse... soldering iron! Stat!
I figure the unit would be on long term/indefinitely hence the exclusion of an auto start for the dividers and synchronous motor but could one be added?
One question I have - since we know from relativity that both gravity and velocity have an impact on clocks - how did they take it into account when flying clocks around the world? Granted, it's likely not to be a huge effect if you're just going by the mechanical clock with 10us precision, but is that the reason? The effect of relativity is simply ignored because the clocks weren't precise enough?
I was thinking the same. Didn't they fly atomic clocks around in planes as one of the ways to prove relativity?
Just a guess but Marc may showed it in another video: you phase sync to identical and take off. After touchdown you compare the shift.
Effects of relativity did not matter for this round, which was a 1 µs sync. It starts to matter when you want to do better than a few ns sync and fly your clocks real fast.
I would say the changing inertial reference frames due to gravity and acceleration were not significant for this level of accuracy.
sorry that I did not understand but, how originally this motor starts itself? is it that right now You give it a little twist that it can run on single phase, but to start itself does it needs a two phases ?
It looks as though it was always designed to be started manually.
I do have one question; how do you set the time?
It's a whole adjustment ceremony! Open the rack and slide it out. Remove the many screws and remove the metal plate that's over the wheels. Rotate the minute and the hours wheels by hand, there is a little lever to free them up while adjusting. The seconds has a clutch spring lever clutch, so you unclutch it and hold it. Start the clock by spinning the motor. Release the clutch at the right moment. Then adjust the tick by cranking the handle while looking at WWV on a scope. I need to make a video on that!
As beautiful as these constructions are, I'm grateful for the invention of PCBs when I see Marc chasing faults in this 3D labyrinth.
Salute Dr Paul Eisler
True, but nothing beats the smell of molten solder from the stone age 😊
PCBs and ICs are widely over-rated. You don't need them at all ;-)
Testing if the coils are resonant - I half expected you to break out a GDO!
The one thing I don't understand is, do you have to open it up and flick the switches and spin the motor every time you turn it on to use it!?
Since it's a clock I assume you would leave it running often, but the idea of having to take it out of the sealed rack and remove the cover plate to spin the motor sounds... cumbersome!
My guess is that interfering with either of those elements would destroy any precise timing that had been established. It would be critical that they were not touched during operation. The internal coverplate doesn't need to be removed to spin the motor.
Done on purpose, so the clock can't be changed easily. Also, it stops dead in its tracks if the 100 kHz disappears for the shortest moment, as the regenerative divider will stop and won't restart. It's a "feature", so it will not restart and indicate a time that's not traceable to the atomic standard without anyone noticing.
@@CuriousMarcI would have thought that it should be accessible from the front behind a cover with a tamper proof seal.
Presumably in its new life, the unit won’t be used in any terribly critical applications. I wonder whether the Arduino could be repurposed into a discreet start-up sequencer. “Pushing” buttons would be easy. What’s a good way to spin up the motor? A tiny tiny version of an automotive starter motor would be ridiculous, but fun. 😁
As Spock would say: Fascinating 😉
@richardlincoln886 - 2024-11-08
Question - the bootstrap startup process: click the button, flick the motor
That's all inside the case - you have to dismantle that box every time you get a powercut/cycle the power on the clock?
Cheers.
@phuzz00 - 2024-11-08
The main workings seem to be on rails inside the box, so I think you undo the two big thumbscrews on each side (labelled 'open'), and slide it out just far enough to flick the switch and spin the motor. Then slide it back in and screw it shut.
I guess you're intended to leave it permanently powered along with the atomic clock.
@CuriousMarc - 2024-11-08
Yes you do have to open it up to restart it. But the clock is supposed to be powered by the crystal source, which has one internal and one external battery backup (that's why the input power is 24V DC and it has no mains plug). We'll demonstrate that when we run it with the HP 106B. The clock is useless anyhow as soon as it stops, you have to realign it to an atomic clock no matter what, so in practice that's not a concern. What would be terrible is that a non knowledgeable person could restart it easily and you would not notice that it had lost atomic traceable time.
@paulstubbs7678 - 2024-11-09
@@CuriousMarc Yes it should only be restart-able by men in white jackets (or whatever time boffins wear) with lots of letters after their names, front panel button proders (as in every day domestic clock restarters) need not apply for these jobs.
@MarcoTedaldi - 2024-11-10
@@paulstubbs7678 you forgot the fancy pants! :)
@anthonylovell2271 - 2024-11-10
@@MarcoTedaldi they come with the jackets 🧐