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- เผยแพร่เมื่อ 11 ม.ค. 2025
- Dave's Ignite Video:
• Dave Jones - make a li...
Teardown Tuesday
How interesting can a box with switches and resistors be?
Not very? How about a multi thousand dollar Genrad 1433 metrology grade decade resistance box?
IET's video: • GenRad 1433 Decade Res...
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At around 17:00 where you talk about the .1ohm metal strip resistor decade, I think they are not burned for calibration, I think some previous genius user just passed too much current thru them. If this resistor is .1ohm, and the rest of the circuit is < .01ohm, a high current will for sure damage it, leaving the rest unaffected.
The resistance Flat is Manganin (CuMn12Ni) or Zerranin which is ultra stable with temperature, the resistors will be varnish dipped or some companies used Shallac to coat their resistors, Don't use Silicone or expect the wires to fail after time !
IF you look inside a Cropico or Sullivan Resistance Box's then you know that you have a great Resistor Box :)
The darker resistance shows you it's been overloaded for sure on the very low range ! that's what happens to manganin when people overload it !,
Retired UKAS manager of a Electrical Standards Laboratory, over 43 years exp,
Resistance wire Look at a company called isabellenhotte, Heusler GMBH KG Dillenburg Germany :)
If you ever look this far back Dave? The wiring is almost definitely solid silver, not plated. Silver was demoted from precious metal status some time ago and is fairly cheap. Loved this, those switches are like the ones in my old AVO.
As an apprentice I used to re tip large circuit breakers. All contactors and switches that I worked had contacts made from Silver cadmium alloy.
Quad Tech at one time had bought the Genrad/General Radio R:C bridges (165X/168X series) and other metrology/component measurement line. Some time after that, it all ended up with IET.
I use the IET RS-201W at school. Actually three of them at a time. Didn't know they were that expensive...
Good video! I love the fact that interesting detail hides in all sorts of corners of the world.
It's two resistors in the box. Part numbers are on the front.
Yes, very distinct possibility they were hand picked.
Vishay bought Dale a few years back...they inherited what is probably the best precision resistance design team in the world...
Only the best! Heck, i sat all the way through! I love it! i don't know why, i watch more of him than i do of actual TV shows, plus i learn a HELL OF LOT MORE
The replacement switch looks like an multi-tech industries model 820 "Test Equipment Grade Switch" i used before, they cost around $100 for one single deck switch.
Ooh, post some photos on the forum!
I'm not sure it's legal to have this much fun watching an electronics video?
I counted 84 wires on the 10k element..
btw, nice camera!
I guess having loads of turns of lower resistance wire makes it easier to calibrate?
Only Dave can make a 35min video about a resistor decade :)
I would never have guessed that a box of switches and resistors can be so interesting inside, Thumbs up !
Tellurium copper sounds almost as schmick as gold-pressed latinum.
Sounds schmick, but it's really just a great machining grade copper. Unlike dymalloy or oxygen free copper.
I really want the precision inductance box!
I use a GenRad bed of nails tester at work. Kind of cool to hear the name here.
I wonder why Hakko never cleans off the flux on the PCBs for their ceramic heaters...I noticed that on my new soldering station.
Someone needs to find a way to make (or find) a replacement lighted display for these HP machines.
Maybe adding an led strip light on the outside, just above (or around) the numerical display ???
(....perhaps using "side emitting" LEDs ?)
+Randy Leifer ....I'm gonna order some side LEDs, and try it on the outside.
I know LED numericals have a preferred sight alignment....we'll see if this messes with that.
I know....it may (or will) cover-up some faceplate lettering info, but perhaps the LED light is held with magnets or sticky-tape, for easy removal.
And I know, I'll get ridiculed for being obsessive.....the joke reply would be,
"just put a cheap Fresnel lens in front of it, you old man !!.....lol"
FTIR frontlight retrofit? FTIR = Frustrated Total Internal Reflection. You look at the display itself, if it has any overhang of glass that you can shine into, you try that, perhaps the result is good enough. Otherwise, you get a piece of glass or acrylic that overhangs your display to act as a light guide, shine your LEDs into the overhanging edge of it, you can cover the edge with a reflective material to minimize light loss, you can sand the light guide perpendicular to the light distribution direction, and finally you glue the light guide to the front of the display with LOCA. I have not tried it yet, so i can't vouch for self-made light guides, but it's on the to-do list.
Just watched your Ignite video Dave, fantastic work!
Cleaning and proper conductive lubricant is not only required, but expected.
EEVblog I just had a look into my "new" 1953 0.02% decade resistance box, and it is amazing how all is the same, but different. Also heavy switches, but different design (inner ring makes contact to outer), wire wound but on little tubes instead of strips, manganin instead of the likely used constantan or isaohm in genrad... but still only twice as good ;)
Hi Dave,
Great hack! 2 things.
1) At 19:25 you say that you were going to link the page pages that you were browsing and did not. Please do.
2) Could you tell that the replaced selector switch felt different from all the rest before opening it up?
The highest precision resistor I have was made by Cinema Electronics back in the 1960s. It is a foil resistor with mylar insulation on a ceramic former, rated 900K ohms at .001% tolerance...and I know there are ones made to substantially tighter tolerances than that...
Yes, it's very easy to get a very precise resistance value with a box like this, and much harder to do so with a pot. Trying to adjust the lower resistance ranges precisely would be practically impossible.
That gunk on the contacts looks a lot like old grease.
Hi Dave, do you think one of those Gold plating kits off eBay might be good to use on electronic contacts? I was thinking about getting one, but not sure if they're useless or not. Perhaps the Gold plating on electronics needs to be much thicker.
just watch you on that Dave's ignite video.. you were great!!!! regards from Portugal (not Spain)
I have a GR decade box from the 1930's and its internal construction is almost identical!
The silver contact issue doesn't relate to the value of the resistors on the particular decade. The contact resistances of all the switches, which are in series, add up and affect the the least significant digit, so the combined switch resistances is what is important. If set to zero, only the zero contact need be silver. If the two highest decades are not set to zero, the selected resistor values swamp out the contact resistance, hence the silver is not needed on the non-zero contacts..
Even though some of the resistors are "just" 0.008%, could it be possible that the once they have actually used are hand picked (measured) to be as precise as possible?
Dave, your speech was awesome. You're so funny! I wish I had better speech skills like you.
Watched your short talk....brilliant...
I think your 10k standard is actually a Z201 0.2ppm typical, max 0.6ppm resistor, not 2ppm! Going by part number
For removing gunk, i use KONTAKT 60, that is great stuff!
(8:30) - But you said you've got two of these.
Open up the other one and compare them both.
>
EDIT:
(8:50) - Shit! You just said what I have written.
I always pause and start banging away.
I've gotta learn to watch the whole vid through.
>
looks almost like the silver wore off from constant use of the upper order decade switches.
Nice Teardown Dave....
Dave no link appears when you reference the Sydney talk...is it my settings? I see the link in the description.
I clicked and the video paused. A master ruseman!
content is king indeed!
Amazing talk you did!
You're so enthusiastic! I LOVE IT
I watched the other video and its a great inspiration of what is possible if you put the hard work into it. I've got ideas about launching my channel, but its dedicating the time and jumping into thats my problem.
First, I'm surprised your meter doesn't have a zeroing function. Second, at some point you must consider your meter's specification and calibration. Third, the screw contact has less resistance and variability than the banana plug so it would be more precise to use the screw contacts for the current and the banana plug for the voltage sense.
Imagine how much lacquer the gals who assembled these breathed in
The wire in those resistors is probably nickel or nickel-chromium alloy.
Correction: Only Dave can make it so you actually want to watch it (:
EEVblog 17:55 Don't you think you pressuring your Amateur radio crowd a bit to much on their soldering skills, Dave?
Jon Williams U mad or something?
No, but it think he is being stereotypical about the solder joint. They don't have to be all that pretty, as long as they work.
Jon Williams Oh, I thought you wanted to say that Dave only has stupid people as fans.
No, but he claims that Ham radio operators will have a bad solder skill. Some of us are electronic engineers with more advanced soldering equipment then just a hack job.
+Jan's The Man so you pick the part where he says that it doesn't matter because it works to point out that they don't have to be pretty as long as they work.
Just in case Dave sees this I have a question regarding your homemade reference resistance box. Did you solder the precision resistors or are you using some form of mechanical connection? If you soldered were there any risks of resistance drift due to component heating?
Bigrignohio Soldered. They are very tamp stable and are rated for soldering. Even so, I used long leads and a heatsink. The resistor wouldn't have heated up at all.
EEVblog Thank you. I don't think I will need QUITE as good a tolerance limit as +/-0.005% (those things are expensive) I do believe I will make a similar reference box. Besides it would be nice to have something relatively precise and portable as I go looking at old meters. Getting back into the hobby I am naturally drawn to those old Fluke bench meters that I could never afford as a child.
When you were testing at around the 33 minute mark, did you intend the leftmost dial to be clicked to "1"? Oops? :)
You were also averaging over 10 of them.
So cool. Thanks 🤙
Are meteorology standards more strict than, say, military?
Patrick Donovan Metrology standards are the ones all other standards are adjusted to, there is an entire hierarchy of precision ultimately leading up to the correct-by-definition standards held in Paris France, because that's where the international metric system was originally established, and where countries still meet up to coordinate improved definitions.
I stopped count after 4. Good job
Thanks for a great video, I have something similar made in Russia, The switches are exactly the same.
Interesting that they wrote the NATO Stock Number right on the thing rather than putting it on a label...
wait what are these used for
What are these resistor boxes used for?
You can use them for maintenance on an electronic system for instance to simulate/calibrate a sensor reading. Or it could be used to experiment with different resistance values for a circuit. Or for calibration of another measuring device like a multimeter. Lots of good uses.
Like a pot? In my case the one I have is big power resistors.
Yup, exception much easier to dial into an exact resistance instead of trying to fiddle with it to get it where you want it.
I would say characterize a sample over a given series of resistance values to check specs
I wonder if the gunk was left because it counts as part of the resistance lol
EEVblog #461 - Genrad Decade Resistance Box Teardown
Unserviceable just means it's cheaper to throw it away than pay someone to clean or maintain something. Instead of cleaning [PC] keyboards at my work they just throw them away.
haha that talk was awesome. You're really funny and well spoken, you should make some extra money doing talks at universities and Engineering seminars
what would this be used for? I know it's a ignorant question, but I can't imagine needing that type of precision...
WD-40 originally from Australia?
I had seen that video and i discover that you should make standup shows
GT85 with PTFE
Nearly clicked past this one but glad i didnt, good one Dave thanks.
I thought military devices are optimized for robustness not for accuracy.
Accuracy is crucial in metrology.
knik3 But some military applications need precision, such as hitting an enemy in Russia all the way from Australia. And the details are obviously classified, so they can't let outside labs see it. Thus the logical option is to have their own lab staffed with military people doing the work. Now the civilian reference gear they used wasn't itself secret, only the jobs it was used for, including the when, how and who. But decades later they can sell the old tools without revealing it was used in any particular year or month (thus ensuring enemy analysts can't correlate with when a particular weapons system was serviced or a particular remote observation was made.
Some military devices are made with solid gold traces with in house laser trimmed components using state of the art test sets calibrated by in house metrology departments. If therethere's an extra decimal or ghz to be had its on next year's budget wish list. It's not all just pull it from the oven stick it in the freezer drop it off a truck an see if it still turns on. Other stuff is pure crap that technically meets contract but really is better used for target practice lol.
great video
0:48 "Switch pornography, I think" I just switched to gay, but it's not what I needed
Supposed to switch the other way, or the wrong contacts might touch
Constructive criticism: Might want to keep check on the um-ing and ah-ing. But great vid as usual.
Hehe :) because how he liked it :)
He did a pretty good deal with this auction :)
Tear down the DIY 20.00 box. Please
This thing is the owls eye
Hi Dave, WD40 is a lubricant killer, it's grate cleaner but at the same time destroy all lubrication abilities. How do I know ? Ask my door locking cylinder and my cycle gear.
Awesome...
Bitum resistor
WD-40! Who da thunk! Certainly significantly cheaper than DeOxIt!
Is anyone else just a little disturbed watching Dave having an nerdgasm on screen?
WD40 ftw. A good lubricator of ceased bolts and a temporary hydrophobic coating for electronics
Ahh. Thanks
Those dials are pimp
Whoa , whoa ,whoa, you need a better warning for this kind of switch pornography.
it was a good product.
Look at his shirt
neat
I counted 70 turns
metrology* save
love the Mythbusters shirt
Then use a real computer :->
I am the waffle master!
Pornographic
lol I´m the 20 000 viewer XD
First!
Check out WD40 history. It's fish oil.