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- เผยแพร่เมื่อ 4 พ.ย. 2013
- What's inside a vintage Fluke 5450A Resistance Calibrator used in cal labs to calibrate multimeters?
Schematic: assets.fluke.com/manuals/5450A...
Coto reed relay: www.farnell.com/datasheets/148...
High Resistance measurement with a relay matrix:
• EEVblog #38 - LCR Mete...
• EEVblog #38 2of2 - Sei...
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I enjoyed your video alot. Especially the accent. I started working at Fluke almost 40 years ago next month. My Boss was one of the 5 original employees. My favorite part of my job has been the math, used to match resistors per drawings in order to make these instruments so precise. Thanks for admiring the dedication that I still put into all my jobs that I do here. Cris Dodds
Wish I could afford your equipment. I have to settle for the best Chinese equipment I can find like Rigol.
You deserve respect 👏
I had my Fluke 5700A calibrated by Fluke just last year (2015). The cal cert includes a 5450A. So you could say it's still a relevant unit.
I loved how u talked it down to a box of resistors in the beginning but it actually ended up being quite a work of art at the end. Good video pretty neat stuff.
Test equipment doesn't do a whole lot for me, but I really enjoy seeing what people go through to achieve high precision. Another great teardown, Dave.
Even if you used modern $20 resistors, you'd still need the special relays and careful design shown in this design to give the same functionality. The product may be vintage, but the design rules are not!
One of the best teardowns yet, this thing is like a piece of art.
I love your videos. I'm new to the EEVBlog and have already learned so much! Thank you very much for taking time out of what I'm sure is a busy schedule to make these videos!
My cat and I both enjoyed the video although the cat was more interested in pawing at the screen trying to catch the black pointer you were waving around. :) I also noticed at the 25 minute mark the schematic mentioned the use of special "telfon" standoffs.
Dave the plate in the 1ohm resistor is Mica not plastic.
"Each manufactured and hand assembled by nude virgins in Utopialand. Tested by graybeards. Beautiful." :D
Those solder joints are beautiful.
This thing is a serious piece of art.
Sprague is still around. Lots of people use them to restore old televisions and radios because they tend to last. Great video as always!
Awesome video!
Yes it is, good catch!
25nA half of a bee's dick - cannot stop from laughing :D
MrocznyTechnik i
So, about that linear regulator, two ideas:
1) To keep the heat from bothering other parts?
2) To make sure that it was conducting heat out into the chassis, but they didn't want any stresses on the chassis being transferred into the linear regulator's soldering points, so they used the flexible cable for a standoff?
I like the second idea better, could it be something else though?
The shielded wound resistors are wound on mica insulators that were also used in HV vacuum tubes, great insulation values.
Maybe your best ever. I will never have a chance to see this tech. Many thanks.
"All the electrons are going to fall out." LOL
Dave, you know why you're successful?
Because even when I'm not particularly interested in the topic I still make time to watch you because I know I'll always be entertained.
Thanks mate!
That was wonderful stuff.
In our lab we're still using a vintage Wavetek 4808 multifunction calibrator but we've characterized it over a fair few years and we can get fairly good uncertainties exceeding the original specification, good enough for most 8.5 digit long scale DMMs anyway.
Re 12:30 - Sprague joined Vishay a decade or two ago.. and I wouldn't be surprised if they were still behind their power elcap series.
Very nice video! Thanks!
This thing is beautiful
Some of the "early" gear was sure built to last. Some great history and finds for the teardown tuesdays.
One hot peace of electronics Dave.
lol @25:10 "telfon", 1979 original typo!
ah good old Zilog, Z-80 how much fun we had with these in 80's :-)
your screwdrivers still amaze me
Never heard of Potter Brumfield? They were huge in relays.
One of those should be nice to have in my collection 😊
Always a fun time
It's probably a silver-tin alloy with high silver content, and I would imagine that it was soldered without flux, in a glove box under an argon atmosphere.
The bus company I worked for used them for the chassis power circuits. P&B "ice cube" relays were rated at 40 Amperes, while the rest were 30A or 20A.
We only used P&B and Bosch. Now, my current company uses Tyco relays that I believe are no longer made in the USA.
Hi Dave the Screened area is a ribbon wound resistor on a mica former
I'm not sure why they exist, but they do make GPIB 488 to USB adapters! 25 years ago we had a Tek plotter with a GPIB interface donated to the art lab at my college. Sadly, we didn't have anything that would talk to it. Didn't have the internet back then to look up Microchannel GPIB cards! :)
I stand corrected. A lot has changed in the world of component makers over the last 25 years. At least the name hasn't been bastardized like some in the industry. Thank you for the correction.
i have heard of Potter and Burmfield (P&B) i have a 4PDT relay from them in the original box. the box says that they make electromechanical relays, solid state relays, time delay relays, specialty sensors, circuit breakers, solenoids, contactors, sockets and accessories at least at the time this was made, the box also says made in the USA
I didn't know boards had care factors! Awesome :)
I always find it hilarious how Dave just can't quite resist poking at things. Not saying that the little taps with the plastic spudger would actually do anything but with all the talk prior to popping the lid off... :P
We have 4 of these still in use at the NASA Marshall Space Flight Center. They still serve their purpose.
14:55 Potter and Brumfield also make LOTS of resetable circuit breakers and switch breakers for aircraft.
Very cool. I would love to see the inside of those various relays and resistors. Obviously this would be destructive but hey... :)
Not only are the relay poles in parallel, they're in inverse parallel. The wiper end on one pole connects to the fixed contact on the other pole. I wonder if that's for easier PCB layout? Or is it done that way to minimise the effects of the metal-to-metal contact in the relay? Thermal EMFs? Differences in contact resistance with polarity?
I worked on pro VTRs and one maker abbreviated "Record Tally" as "rectally".
I need an extender card before I can further do anything useful
Fascinating! Telfon!
Tohms? Where i work we just call that "open"
What is that, the resistance of 1 foot of vaccuum on the moon?
would have been cool to hear the relays
I always wanted the Fluke 5450A resistance standard, but what a cost in those days & these days,
I like it, but 4 Terminal Resistors in oil bath are far better
The resistance wire used is probably constantan or manganin or something like that. Low tempco alloy.
The relays do NOT have to have ultra low or ultra consistent contact resistance in 4-wire mode. The inherent advantages of 4-wire mode apply to relay contacts as well, as long as you invest in double the number of relays, or dual-throw relays (since you need to switch both sense and force).
Yes, ULN2003 drivers.
What EEVblog means is "if someone would kindly loan/donate an extender card, i could go further" :]
28:00 I think it's Glimmer. It is a very good insulator and can handle temperatures around 600°C (soldering).
TIL: "Glimmer" is the German word for "Mica".
That 'plastic see through former' is mica sheeting!
@10:57-"you're only talking ten nanoamps... it's naff all, half a bees dick" HAHAHA! I love Aussie slang.
Thanks for the video Dave. You're just as entertaining as you are informative, as usual :D
Travis Bigelow 10:57
I wish I could offer 2 thumbs up! Very Neat.
27:00.... Now you know where the zig-zagged resistor symbol comes from...
ve2zzz 27:00
The Coto equivalent for that is 1240-0177, according to NSN Now.
Now THAT's a horrible thought:-)
Thanks for another great video, Dave! How is that impressive back-to-the-future display doing? I would love to see it working!
I still dont understand anything one bit, but i watch the entire thing.
Unlike modern DMMs, most meters at that time read up to 2, 20, 200, etc. I guess 1.9 was near full scale.
considering its a ten year old design at the guesstimated date of production maybe the flatflex was added to accomodate some change in production at some point during the lifetime of the design
Those 1 and 1.9 ohm resistors are wound on mica sheets. Same as normal heating elements.
PS- I'm not a nude virgin.
And there was none of them involved in assembly process? I'm kinda disappointed... :D
Cris Dodds Hahahaha. Great work, Chris.
19:42 I found a website that could give informations concerning the electrol relays
You be surprised!
Potter & Brumfield was *THE* name in relays here in the states. At least they were when I cut my teeth electronics-wise.
whats a moldymeter?? sounds nasty!
ericsbuds This accent is one of the may rsns i watch eevblog regularly😂😂😂
agreed. I was trying to make a joke but I am no comedian.
potter and brumfeild some of the best relays you can get.
28:00 With the solder connections to those resistors, I doubt they're nicrhome. Basic metallurgy - solder takes to nichrome about as well as it does to aluminum. Of course Dave probably realized this moments after he said "nichrome".
The spare fuses was a nice touch. I also noticed next to the huge blue Sprague cap (look at the size of the bracket!) something held in what looks like a fuse clips but it has leads and is soldered in place. What was that? Why the clips?
you have to be careful with that,its really hard to put them back in if they fall!
While it is nice to see the guts of modern gear, those teardowns are usually not as fun since its alaways some BGA SOC processor, meaby a FPGA and varius tiny SMD bits around. While in vintage gear you always see some neat tricks they used to get around the limitations of technology back then(I absolutely loved the vintage high speed camera teardowns that tesla500 did)
As always enjoyed it. Do you think the clear 10 ohm former cards could have been Mica?
It's probably a mica, not acrylic boards (on which 1 and 1.9 resistors are wound).
Are you giving up on the DSA? I believe in you! I know you can do it.
not sure guessing:
0.1 + 0.9 = 1
1 + 9 = 10
10 + 90 = 100
100 + 900 = 1000
So when you connect all the small ohm together with the bigger ones, .you get 1.. stuff.
Schrodinger's resistors under the can, looking at them changes their value...
For some crude stuff, yes.
Okay, but what I didn't see are the back-EMF protection diodes for the relay coils... or, for that matter, driver transistors. Dave, did you note any ULN-series driver ICs for these things?!?
"Upside-down, all the electrons are going to fall out..."
I wonder how many people would actually fall for that :)
Dave,
Does the amount of dust on that board cause any issues with the resistors? Thanks!
Aren't those mica sheets at 27:17?
15:15 low right corner XD
Yes, it's just you!
Maybe there's components in there to help repair the DSA :D
Can those resistors and other parts be re purposed for other devices? eg repairing cheap electronics :)
One thing I wonder, how do they get the initial calibration for the first ever device, eg who made the first ever resistance standard and how did they know when that was accurate when there is no other calibration device to compare it to?
That's a really good idea.
What brand do you use? ;)
Is your calculator RPN?
That's what I was thinking.
Moldy meter?
how does a relay with two pins work and what's the point of it?
+Sam Brooks You can't see it in the video but there are 2 additional pins below the main body to energize the coil.
Where do you get this stuff man
I wonder if you would need to use a special high conductivity solder for such a unit? , and what would that be? , high in silver?
Potter & Brumfield common in USA
Beat me to it!
Have you heard of American Relay?