"GREAT" Meter! The HP 419A DC Null Voltmeter, [RESTORATION]

[@MrCarlsonsLab]

To learn more about electronics in a very different and effective way, and gain access to Mr Carlson's personal designs and inventions, visit the Mr Carlson's Lab Patreon page here: www.patreon.com/MrCarlsonsLab

[@KaizerPowerElectronicsDk]

I got a Danish produced "Type OSG 42b" from Radiometer Copenhagen, if you are interested in a presumably rare scope. (that needs to be fixed)

[@glynwatkins9968]

good job Paul

[@BruceNitroxpro]

@@KaizerPowerElectronicsDk , I sure would enjoy that restoration!

[@guadalupe4131]

@@KaizerPowerElectronicsDk que

[@guadalupe4131]

@@glynwatkins9968 de casas

[@michaelberry1028]

As an old HP engineer I really enjoyed this one, a great restoration.

[@MrCarlsonsLab]

Thanks for your kind comment Michael!

[@JohnDoe-ce2wl]

I see you haven't uploaded any videos, but I imagine you'd have some interesting stories to share with younger generations of engineers and hobbyists. Give it a thought :)

[@Satchmoeddie]

I really love the old HP gear! Too bad their laptops and desktops are junk! A neighbor gave me a working 1963 HP O Scope that had been converted to a fancy precision "strobotach" for the FAA. Basically they removed the brightness potentiometer from the brightness control and used it as a very precise and fast strobe light. Funny story, it had an old phone number on it from the 1970s, and I called it on a lark. It went to a desk inside of some government lab, and the guy who converted those was still at working that desk. He was very surprised to get a call to say the least. When I told him how I got that number we had a really nice conversation. I have two Fluke differential Volt Meters. I still have that nice old HP O Scope. I thought about pulling the 50+ Phillips made HP ECC88s, but I cannot bring myself to rip it apart. They were never used as they are in a section that did not get used in it's life as a precision timed strobe light. HP/Agilent/Keysight is THE go to for spectrum analyzers. HP computers has destroyed the HP name. The Bill & Dave days are long gone. HP seemed to always play catchup to Tektronix with O Scopes but HP had their own domains no one else could touch.

[@derkchurk5879]

@@Satchmoeddie never had any issue with hp products, like Dell and the rest, sounds like user error to me.

[@stephenbrough8132]

@@derkchurk5879 Their brown sauce is good too.

[@001desertrat3]

At 73 years of age , I thought that I had seen most everything . . . . and then you show me a Lit Neon Bulb that's Afraid of the Dark . L O L !

[@urrick33333]

Oh yeah. What an anecdote

[@God-CDXX]

fear of the dark good album

[@goldpipe2003]

I have three of them in a lamp that has a dimmer and they will not work in the dark

[@teresashinkansen9402]

What a coincidence, i discovered this by accident about a month ago. On my storage shed there was a plugged power strip with a neon bulb in the switch but i thought it was off, I turned on the light and no light, the light bulb of the shed was dead so I grabbed a flashlight and as soon as I approached with the flashlight the switch started blinking so that caught my attention, i turned off the light and it turned off too! i was quite perplexed and i stood there playing with it like 5 minutes illuminating it and seeing how much light i needed to make it glow. photoelectric effect! so cool

[@robertc.2465]

Now there are two 73 year olds that thought they had seen it all, almost.. a nyctophobic neon. Plus all the other possible electrical characteristics!!

[@garbleduser]

I absolutely love what you do! This is a perfect example of something I refer to as a "vengeful act of kindness." That is where you find a piece of equipment where a manufacturer tried exceptionally hard to prevent people from repairing it, and decide to share the obscured information with the world. Thank you for your vengeful act of kindness Paul!

[@hullinstruments]

Vengeful act of kindness… I immediately thought of plenty of ex girlfriends that fit that description perfectly

[@BruceNitroxpro]

@@hullinstruments , Hehehe, OMG

[@krz8888888]

It's interesting to see generations of brilliant engineer's work come through your bench. Lots of those are long gone but we can still appreciate their ingenuity and thought process on this channel

[@steveyoung8560]

"Took the neon out of my night light and tried it." Now that's a man on a mission. Great video, Paul.

[@jwingo7257]

Paul, You have a gift of explaining such technical engineering in a hands-on tinkering way. Your tinkering, building, debugging and inventing would make Edison, Westinghouse and Tesla proud. You epitomize the human desire and discipline to learn and to build. You are an inspiration for every nerdy, inquisitive kid interested in how/why things work.

[@BruceNitroxpro]

J wingo , And for 80 year old guys, too. Just a great guy.

[@scumminguk]

i have no idea what your talking about but i am now a subscriber.

[@paulpaulzadeh6172]

watch this channel serval time per day , watch this video 3 times , never get tired of you , you are real EE ,

[@hestheMaster]

This was an incredible restoration of a very sensitive voltmeter. The attention to details on rebuilding and re-engineering of it's inner workings shows how great of a technically skilled person you are Paul. Thanks for showing how you did it. Much props to you!😍

[@rtybn2012]

What re-engineering, all he did was copy an existing design from the original schematic and tested a bunch of neon bulbs. Anyone on this forum could have done the same thing.

[@BruceNitroxpro]

@@rtybn2012 , Sure they could... but didn't and won't... cause they can't.

[@johnyoungquist6540]

The neon chopper was a silent breakthrough used in many instruments like the hp-410C VTVM. Other methods at the time were mechanical and used motorized spinning disks or noisy vibrating reeds yuk! Stable low drift DC gain in those days was hard to get without choppers. Now we would use a single monolithic chopper amp. Neon depends on alpha particles from outer space to provide seed ionization to work in the dark, otherwise ordinary ambient light does it. Lamps that had to work in the dark employed radioactivity. A little KR-85 a radioactive isotope of krypton gas mixed with the neon was often used. Some sort of radioactive electrode or green uranium glass might do it too. The exact neon bulb might have been a carefully guarded secret at the time to prevent copying the design. The little bulb was so common at the time who would think it was special? It would look the same as any other lamp. They would not have unlimited life and for something people left on all the time replacements would be inevitable. The LED solution is the simplest. The 25% duty drive waveform is easiest to do digitally with logic. Careful frequency selection could improve line frequency rejection. Take away all the pre-made solutions we have today and most engineers would be lost.

[@MrCarlsonsLab]

Thanks for taking the time to write John. You know your stuff, that's nice to see!

[@ciprianpopa1503]

"Neon depends on alpha particles from outer space" are you sure about that?

[@johnyoungquist6540]

@@ciprianpopa1503 The alpha particles could come from any source I suppose. I did a lot of work on neon plasma displays many years ago, alpha was the prevailing theory at the time, I don't know if anyone cared where they came from. I did get some other radioactive stuff near a dark display and it worked. We considered using uranium glass instead of KR-85 but it wasn't clear we could get that approved. KR-85 was eventually eliminated from the displays because of AEC. It was disastrous. Many changes were made to try and compensate for the loss of radioactive gas none were very good.

[@ligius3]

It's true that we would get lost, this was ingrained during education. I think there is a purpose to it, that people don't design 'magic' solutions that would not be understood once the original designer left the team. I got failed for a practical project in university because my hand-crafted component selection, which got 100x less noise than spec, was not the tried-and-true design. Left a bitter taste in my mouth and decided to pursue a different line of work, where creativity is accepted.

[@ciprianpopa1503]

@@johnyoungquist6540 What you describe sounds like something similar to a spark gap tube and they work by ionizing the gas inside the tube via gamma radiation. It's true that some isotope used emit alpha but they are secondary in importance, and the alpha (He nuclei) coming from outside the valve are not affecting the tube function whatsoever since alpha travels 0 through glass.

[@rebelba42]

I can't even imagine how many work hours and sleepless nights you had to put into this project! Awesome! In my opinion, only Ben from Applied Science would have similar love to detail making such an intense neon bulb investigation! I never would have the patience to do that but thankfully it dosen't matter: We have you, showing us all those traps and possible solutions! I still remember Fran's videos about YT, monetising and content pushing etc. Making educational videos running over 90 min with this level of quality can't be easy these days. Thank you very much Paul for doing all this hard work! Have a good weekend!

[@MrCarlsonsLab]

Thanks for your kind comment Ralf! Yes, this meter was "one of those" projects. Have a good weekend as well!

[@deathcube2006]

As an electronic engineer myself, I find all your videos really interesting, as you have a real deep well of knowledge, and always learn something new with your vids!. You should have a lot more subscribers!

[@hondamanusa]

When retail gives you lemons, he tells them to shove it and makes something sweet. Keep up the great work!!

[@CoolMusicToMyEars]

The Fluke 845AB Null Detector also had a optical chopper, The Fluke 332A, 335A Calibrator had a mechanical chopper early versions, Keithley made a 148 Null Detector that was also fantastic front end in copper box, really love the Old test equipment, lasts for many years, Fluke 5440B Very nice DC calibrator. :) my UKAS laboratory measured 1V or 1.01856 V to 0.6uV accuracy, Retired UKAS Standards Laboratory manager

[@MrCarlsonsLab]

Thanks for sharing your story!

[@jeremyperala839]

Jeez, you're an expert at testing neon bulbs now.

[@bobbyvarnell9350]

I love your dedication to bringing this old gear back to life.

[@HammyTechnoid]

If I'm not mistaken, it was a null meter that Bob Carver used in completing his "Tubes vs Transistor" challenge. He put forth that he could, within 48 hours, make one of his audio amps, which were transistor based, sound exactly like any tube amp. Stereophile magazine took up his challenge, and even though he didn't do it within 48 hours, he did accomplish the task. The amp he had to match was the Conrad Johnson Premiere Four. The design of his circuitry went on to be used in production models of his amps, designated by "t" after the model number. Out of this challenge came the Carver M1.0t, a stellar amp. All thanks to null meter technology. If you can find the Stereophile article, it is a very interesting read.

[@trickyrat483]

All covered - including restorations - on xraytonyb's YT channel, for those who are interested.

[@stevefoudray487]

Hammy Technoid I bought amp back 1988, great home amp, but traded it for live sound equipment.

[@markbatten5178]

I'm kinda sick of neon bulbs now (38mins.) !! I choked on my coffee!! You are the best Mr. Carlson!

[@tunafish3216]

I don’t know a lot about this stuff but I watched the whole video. Thanks

[@renatobordin1601]

Thank you Paul, just recently found one in very good nick with original batteries but not too much of a battery goo mess. Your video is most useful with this restoration of this fantastic instrument.

[@rrowan327]

What an incredible meter and design also your time and dedication to this channel and the hours designing and testing the circuits and Neon Bulbs. My favorite part of the video is "Never wanting to see a Neon Bulb Ever again" LOL

[@garybevis8691]

As always, great videos. You are a special genius electronics guru. Thanks so much Paul, you have a gift .

[@Greg-et2dp]

Mr Carlsons lab your Hp-419A DC Null volmeter is awesome my friend 😅😅😅😅

[@chefbink61]

Another great vid!! This HP Null meter comes from the great HP area when HP was really building good gear!! Thanks for sharing!!

[@fluxoff]

Terminology nitpick: "Rod" should be "electrode" Though I must admit that "rod" accurately describes what the neon electrode looks like, while "electrode" is technically what the circuit element is. As some French guy said, "there is the thing, there is the name of the thing, then there's just what we call it."

[@ke4est]

The knowledge shared in this video is mind blowing and much appreciated! 73, KE4EST

[@MrPetrabella]

I absolutely agree with you, If someone is able to service and even improve old HP T&M equipment he has a deep understanding of electronics and very high bench skills. 73, former HB9ANA

[@BruceNitroxpro]

@@MrPetrabella , You are reading my mind! de KQ2E

[@johnlegros1586]

yes HP was at the time the best ever made , close to physics ingeenering , very good design by true real good engineers

[@absurdengineering]

Robert Slackware Postscript is all interpreted, there’s no such thing as a “postscript chip”, real or not. They licensed an implementation maybe from Adobe and stuck it in on whatever processor was their fancy at the time. Nothing special about it. Modern postscript printers do the same, although they may use Ghostscript internally. All modern networked HP laser printers have Postscript AFAIK and there’s nothing “fake” about it, lol.

[@ElJohnerino]

Pro grade comedy timing at the many tested neons segment. Actual lol here.

[@waynethompson8416]

A great device and a wonderful project for you to share! Man, I couldn't have gone through all those Neon Bulbs...no, nope, never!!! It is an amazing device and I do appreciate your sharing it with us! Glad to be one of your Patreons.

[@WarpFactor999]

Excellent! I've used this meter when it was brand new...mostly with precision Wheatstone bridges and saturated cells for calibrations. Self heating was an issue. You would turn it on and leave it on in a temperature controlled room. Connect your setup and adjust. Walk away and wait. Tweak. Rinse and repeat. Eventually you would get a precise measurement that was , at the time, truly remarkable.

[@jimjimx5418]

It’s sooo nice to see you back on KZbin. We love, and need you here too.

[@MrCarlsonsLab]

Thanks Jim! I would have been here sooner, but this video took slightly over 1 month to create.

[@ianbutler1983]

@@MrCarlsonsLab I can imagine that doing this work, and documenting it, then editing it into top-quality videos over an hour long must take a lot of time. But come on Paul, it is not like you have an outside life to live or a family, right...lol. Thanks for your efforts, your videos are wonderful.

[@KallePihlajasaari]

This is kind of silly, here we have 1700+ people at 1:34:44holding their breath just watching a needle twitch. It looks to be easily over 1000 times more accurate than your regular 3.5 digit DMM made with vintage parts and design. There has been little progress at the bleeding edge of measurement because there is no commercial use case. If we all needed to measure nV daily then there would be a US$1.00 IC to do this with an SPI interface that worked out the box with internal compensation and no settling time and built in voltage regulators and references. Certainly achieving this level of accuracy with normal consumer parts is not very easy even today. Thank you for the lovely video as usual.

[@MrCarlsonsLab]

Thanks for taking the time to write Kalle.

[@absurdengineering]

I think you haven’t played with modern op-amps and ADCs. The performance level of this instrument can be replicated with simple off the shelf parts with very rudimentary engineering effort - because all the hard work was done by IC designers and semiconductor process engineering teams. There are ADC converters that can measure nanovolts directly at the input terminals - you connect them directly to the source, no interfacing needed, and they are all parts you can get for a dozen bucks or two in qty 1. That doesn’t diminish the brilliant engineering done to make this instrument work at all: it took lots of brilliant engineering to come up with an integrated ADC that has the sensitivity and linearity needed for measurements at this scale while still having full scale reading of 1-2V :) I dare say it took a wee bit more effort than this instrument did.

[@MichiganPeatMoss]

To roughly quote from another video: "...The magic is in you... (not the instrument)" BEST takeaway ever! Thank You!

[@johnopalko5223]

The advantage of the neon power indicator is it serves as a reminder to disconnect the line cord when you're measuring on the really low ranges. That's why the front panel is labeled "LINE" and not "PWR" or "ON."

[@aaronjacquet4283]

yeah but when you forget the tag the off switch and can not tell when it's off there goes your battery ... it would have been better to have two lights on it ....

[@johnopalko5223]

@@aaronjacquet4283 I agree, but I can see why they did it this way. This device may be from a time before LEDs were common and a lamp that wasn't powered by the AC line would have had to be incandescent. That would have drained the batteries really fast. And, leaving the unit powered on long enough to drain the batteries would be an inconvenience, but not a disaster. Just plug it in and let them recharge.

[@BruceNitroxpro]

@@johnopalko5223 , Sad but true.

[@rkstr9965]

I'm definitely glad I purchased my HP 419A over a year ago - before the rush! When it was still a bargain...

[@Wizardofgosz]

I'm not surprised at all that any HP device is well made. That's world class stuff. CuriousMarc would love this.

[@thisolesignguy2733]

Oh man, this brings back memories. When I was in college, one of my classes was Electrical Engineering. Every time we had a test, my instructor spent his time working on 419As because we had about 30 of them and something always went bad. So he would spend his extra time scabbing units to build a working one lol. I'll never forget being in the middle of the test and hearing "OH YOU PIECE OF CRAP!!!" and see him grab another one and start removing parts haha. We used to call it our "attention breaker"

[@MrCarlsonsLab]

Thanks for sharing your story!

[@jimgiordano8218]

Very impressive, spot on with a home made board and no adjustments of any kind. I don't know how you do it, but keep on doing what you do. I learn a lot from you. Thank you.

[@ottodydaktyk]

Thanks for all you do, Paul. Checking all those bulbs was a lot of work. It's appreciated.

[@TheJamescatlin]

As a old HP instrument R&D engineer (8683, 8684, 8901B, 8902A, 8920) , I take my hat off to you. I would have done HALF the amount of Ne bulb experimentation because a little voice would be screaming in my ear to do the solid state replacement. Still, like you, I enjoyed the exploration into neon bulb land. Who knew that these ionization bulbs were so finicky? Thanks. Love the channel. BTW, our 8902A was an descendant of the 419A using the same chopping approach to allow us to measure over 120dB of RF power over a single hardware setting!

[@burn435353]

I love these videos, though i'm not an engineer; i work in animation. But i want to say from a strictly aesthetic perspective, these videos are amazing. From the opening shot where you're dwarfed by a room of vintage electronics, to the technical section of the video which is rendered in delicate minimalism. I'm not sure how intentional all of this is, but i can watch it all day, i love it! My only suggestion, and its a minor one, is to cut the sections of audio where you breath in, and replace them with room tone - this is an old broadcasting trick, otherwise 10/10.

[@BruceNitroxpro]

Don Rumata , Shhhh! Don't give away the magic! ROFL

[@michaelrusso7047]

Mr Carson's . I love your videos I don't know much but your videos are awesome your voice is calm and soothing and there's nothing better in the morning then to get a cup of coffee and sit back and watch your videos thanks. Mike

[@Allbbrz]

"no alignment ! that's incredible ! what's the deal here ? " - of course, hats off to HP .. and your redesigned solid state board. Absolutely fantastic ! (like you would say, right ?)

[@lorencing]

Amazing, how does the bulb "know" when it is in the dark?! Never seen that before, what's the story there? And what an amazing device, would have never thought there were lights inside with a reason. And it is just incredible how precise the device is.

[@MrCarlsonsLab]

Neon bulbs don't like to strike or ionize in total darkness. They (back in the day) put a small amount of radioactive gas in the neon mix to help the bulb strike, (Krypton-85.) Unfortunately the half life was about 10.7 years, so they are pretty flat now.

[@lorencing]

@@MrCarlsonsLab just amazing to see what all we have invented. Thanks again Mr.Carlson,

[@stclairstclair]

As a retired mechanic I really get a ton of satisfaction when I restore things, I resurrected A 60's craftsman wood lathe, with some nice upgrades, it came out better than expected, now I use it on other resurrections!

[@StewartMarkley]

Paul, being a test equipment geek, I thoroughly enjoyed this. You did an excellent job both on the 419A and your videoing. I only wish I was as smart and skilled as you are. I’m retired now and especially because of the corona virus I have a lot of time on my hands and your videos are providing a lot of entertainment. I was flabbergasted at the calibration accuracy after all your rework. I used a HP nulling voltmeter back in the 70s when I was on a submarine in the Navy. Lots of interesting electronics on the boat.

[@johnyoungquist6540]

The neon chopper was the heart of several instruments like the 410C VTVM. Its schematic is very simple but specs are impressive. Now we would use a monolithic chopper amp. Neon depends on alpha particles to provide seed ionization to work in the dark so it is flaky. They will work if you drive them with much higher voltage.

[@drstrangelove09]

Silly me, I thought the chip is a 81112 but it actually says Pin 8, Pin 11, and Pin 12, and the chip is a TL494... of course! Thank you for a very cool and interesting video and design.

[@markshaum8364]

I used to work on all the 400 series meters while employed at a HP sales and repair center in the mid 70's. I worked with the "audio" equipment which meant DC to 10Mhz. My favorites were the 400 series meters and 200 series oscillators.

[@FluxCondenser]

Your dedication and patience is astonishing, especially for something as potentially infuriating as bulbs! If I have to spend more than three minutes diagnosing a dead Christmas light string I throw the whole thing in the trash and buy a new one.

[@miguelangelsimonfernandez5498]

I always love watching, again and again these videos. You teach me so much. Thank you

[@kenhorne5650]

Had my old radio delco r1153 repaired like you shared. Got new compactors , tubes, and polarized power cord. The radio repair include alignment and knob. I love listening like used to when was a kid..thanks so much.

[@EI6DP]

WoW - A new travel into the life of neon lamps - incredible.

[@Wes8761]

I want to see a team collaboration project with EEVblog, Greatscott, Electroboom, The 8 Bit Guy, MrCarlsonsLab, and all the other electronics youtubers contributing something. I dont care what the collab is for it would just be cool to see a massive electronics collab

[@Wizardofgosz]

CuriousMarc. I can do without the 8 Bit Guy though. He's not on this level.

[@Uvisir]

EEVblog + CuriousMarc + Applied Science + MrCarlsonsLab

[@MrGogyimogyi]

Thank you, Mr. Carlson! Excellent work and presentation as always!

[@AiMR]

Average KZbin Tech: This meter is worthless, entire Unobtainium boards are missing. Mr. C: Hold my beer.

[@abc-ni9uw]

😩

[@rogervanbommel1086]

Soooooooooooooooo true

[@VintageTechFan]

"I make a new one".

[@furlockfurli2719]

And again. You did it again. Out of this world.

[@bergarteric5713]

Good evening ( or morning ) Mister . Again a beautiful item by HP !!! The master with Teck 's lab's intruments !!! Inside you smell the State of the art !!! nothing else : a great job by a master factory ... Thanks for your explication and the quality of the share !!! have a nice day for you ...

[@pauliedweasel]

I used to use these as well as worked on a few when I was an instrumentation repair tech at Hewlett-Packard years ago in a galaxy not so far away.

[@MrCarlsonsLab]

Thanks for taking the time to write!

[@andrewspar436]

I am so very sorry not to be able to vote up this video more than once! Your work is just so inspiring, as are some of the devices you are working on, especially those outstanding ones like the 419A.

[@MrCarlsonsLab]

Thanks for your kind comment Andrew!

[@fireantsarestrange]

I wonder if there is any low paid college kid from back then working at HP that sat there and plugged these in and out to get a working board. Had to be a really boring job. And then you go in there and totally design a better board that isn't fussy. How you did this is amazing dude.

[@SteverRob]

I used Fluke's 845AB quite a bit in the 90s-2000s calibrating automatic cable testers for the Space Shuttle Main Engines. Also had issues with the ni-cads, and had some NiMH batteries made for it. Like your work here, the new batteries plugged right in to the existing charging circuit. Nice work!

[@spiccybaby]

I've watched this twice now, it's that good. Fabulous work.

[@TrackingWidgets]

Commenting on this video as it's the last one I found when looking to see if you were still publishing. What a great library of videos you've produced that cover such a huge array of electronics topics! I'm going to have fun exploring your offerings, will check out your patreon site as well. Keep it up!!

[@robertcunningham1542]

All those neon bulbs, reminds me of back in 1961, Popular Electronics had a project of a digital computer using a ladder of ten neon bulbs, for each of the digits and a rotary telephone dial for input. You had to get about three hundred neon bulbs and age them for hours, then match them in banks of ten for turn on voltage and extinguish voltage so a pulse would cause them to increment. I attended a state wide industrial student competition, that year, there was about thirty of them entered. I of course entered something different.

[@iainportalupi]

Robert Cunningham I’ve got a copy of the article about that computer. I’ve finally acquired all the neon bulbs for it so someday I can build it.

[@pulesjet]

Back in the time HP created Master Peaces of Electronic Test Gear. NOT any more. SAD times. No one build with the same quality any more.

[@Zonkotron]

Hmm. The latest generation Keysight LCR Meter we got at work is mindblowing. HP was a nicer name, that is true.....only problem I see with modern test gear is the embedded windows.

[@praestant8]

pulesjet Lets be realistic. How many companies are building new analog dc null meters and who would buy them at the price they would cost?

[@DaleDix]

Normally I wouldn't bother but when talking about excellence, it's masterpiece.

[@pulesjet]

​@@praestant8 No one. We gave away our manufacturing and industrial edges or leads. Hell we did that with semiconductors to start . Our insanely inflated wages and prices have all but killed this country. Maybe that's more then in the works.

[@absurdengineering]

I’m not so sure. I got a Siglent scope for order of magnitude less than a comparable Keysight unit and it performs no worse, and its internals look pristine. It’s no less of a “masterpiece” as far as I’m concerned: it doesn’t have to be. Such designs aren’t at the edge of what’s possible anymore. Making a 1-2Gs/s digitizer and a proper input stage is run of the mill stuff nowadays. The quality is in the software, and there’s this little thing called software engineering that would like to interject now and have a word or two :)

[@paulgrodkowski3412]

Nice KZbin video. Nice to see guys like this taking an interest in technology.

[@eddiespencer1]

I keep marveling at the fact that everything this device does can be done with a single chip in a device that easily fits in your pocket today. Incredible.

[@chrisw.3077]

Not as well.

[@Very_Dark_Engineer]

That is something new! Mr Carlson, please, provide more videos about measuring stuff from 80's, technic solutions in this stuff is not so hidden and still very useful for hobbyists today.

[@saintleibowitz8401]

around the time he started pulling out his many bags and trays of neon bulbs, i realized Mr.Carlson may have a problem. which is great news for us.

[@sea-ferring]

This is amazing and beautiful. Just breathtaking!

[@andymouse]

Spectacular work !..cheers.

[@MrCarlsonsLab]

Many thanks!

[@richardgoebel226]

Sick of the Neon bulbs? Us mere mortals would have gone crazy before we were even halfway through all of them. No wonder it was so long since the last video. Very well done.

[@michaelcruz1434]

And I tested these neon bulbs, and these, and these etc etc lol. Another great video Paul!!

[@monadking2761]

Great job! I used to work in Metrology and worked on the same meter at a defence contractor. The problem one might have is static on the plastic or glass of the meter face. We would breath on it to see if the meter would change to test that. We would have to spray destat on the inside and balance the meter movement too. BTW meters are spect at full scale and note your mirror scale, is that 1%? Try checking the negative side as well. Sometimes we would use khromine (spelling?)on the switch contacts or Pro Gold if there were any deviations on the scales. What you did was beyond the what a normal person would ever do in that chopper circuit. Kudos to you! Your knowledge is exceptional in electronics. When I started out it was on the old 545 by Techtronix and learned how to adjusting the slugs on the delay line and calibrated the Simpsons 260s. I still have an old Ecio tube tester I build 50 years ago. Keep restoring this stuf, it is an art.

[@MrCarlsonsLab]

Thanks for your kind comment, and taking the time to write!

[@harrystevens3885]

Never knew there was so much to a neon bulb I will never look at my toaster and kettle again in the same way, I can't recommend this channel highly enough,simply the best on the tube.....

[@absurdengineering]

It should be said that the only reason there’s “so much” to the neon bulb in this circuit is because the oscillator was an awful, marginal abomination. You can make an oscillator that would work with absolutely any neon that strikes in darkness in an afternoon, and it will work reliably and reproducibly without any regard to what neon bulb is in it. The whole neon brouhaha is the result of a despicably poor oscillator design. It is intrinsically tied to multiple parameters of the neon bulb - parameters that are entirely irrelevant unless you design a circuit that foolishly chooses to depend on them. Maybe it was their way of obfuscating things and preventing direct copies. Maybe it’s not obvious but getting a neon to reliably light up is child’s play if you got any reasonable power source for it. The oscillator in this meter is an example of how to never ever design such things. It’s marginally manufacturable and totally unserviceable and that’s not a good thing. It’s objectively absurdly bad of a design. Give anyone a low voltage transistor multivibrator, divider, and two little transformers and you can drive any neon bulb with thus 25% waveform, in a predictable manner, with no tweaking. Even the current adjustment is moot: you design the low-side driver to be a constant-power circuit, so that no matter what the neon does, it’ll produce roughly the same light output since the physical process has losses that are not very sensitive. I.e. if you get two neons of similar size and put 10mW of electrical power into them, you may get x mW light out of both of them, and that x won’t vary a whole lot - certainly not enough to need to tweak anything for each neon! In other words: the people who put neons into toasters and kettles are not going for the most insanely twitchy and unserviceable way of driving their neons. HP, on the other way… :(

[@rpbale]

You have me on the nanos and nulls. Great video. Bravo on the low voltage devices. I have several Fluke null meters 845AB and 845AR's where I've replaced the neons. I never knew how critical the neon bulbs were. I guess I was lucky with my batch. It would be great to see you do a video series on low voltage EMF measurement devices and best practices. I've been restoring a collection of old reference devices from the pre-90's. Guildline, Fluke and HP stuff. There are so few videos out there to help us understand what they we're doing in e-metrology back then. I just ordered an old malfunctioning Solartron 7081 8.5 digit DMM. I don't really know how to use it let alone fix it.

[@lambertax]

That is just...amazing. What a great work. Redesigning such a precision instrument is awesome👍

[@agoodandy1]

We used these when I was in the Marine Corps as a radio technician with them on the TH-81 multiplexers for AN/MRC-135

[@oturgator]

This is pure gold right here!

[@pulesjet]

Used one of these meters on a daily basis in the USAF. They were still in use in the 1990's when I left.

[@Movieman1965]

The military doesn't change equipment constantly. They maintain, repair and overhaul if it's cost effective and still useful. At least that's how it looked to me when I was in the US Army (1984-88) and US Air Force (1989-1991). The little 1941 willy jeep was still in use in 1984 when I joined the US Army. At that time the Hummer(actually known as the HMMWV)began replacing it. That's 43 years of service life! People think the US Military wastes money, but they don't know how long it keeps assets in service. Awesome video as always, Paul.

[@cambo1200]

I have Fairchild 5000 and 7000 nixie meters that were sold with different plug in boards based on the options purchased. As a future project I would love to build these option boards. Love the video!

[@bundylovess]

Wow who would of thought there was so much to a neon light 💡 nice job mr Carlson and big thumbs up 👍

[@nparbs]

I always look forward to your videos! They are so relaxing and education. Thank you Mr Carlson!

[@deanmartin8784]

I love your intros where you're surrounded by all that awesome gear.

[@PNWZombieWatch]

I'm impressed by that analog meter on the front as well able to keep it's accuracy after so long too.

[@peep39]

This has got to be one of your most interesting videos. And that's saying something!

[@DonDegidio]

Hi Paul, It's amazing how well some of the old test gear was designed. Enjoyed this video. Deserves two thumbs up. 73 WB3BJU

[@OleF112]

Great work, Paul. That thing is so incredible sensitive, wow. Made my day to look at the Fluke test. 73 de Olaf.

[@T2D.SteveArcs]

17:40 long screw damage been a problem for a long time lol

[@SkigBiggler]

This video made me go and take a look to see if there was any HP gear for sale locally, found an HP400E which should be of use, the HP gear seems well made and quite reliable, so hopefully with a bit of love it’ll last me for years to come.

[@JurisKankalis]

Although I don't speak Canadian (as an airport clerk said in a newer episode of Southpark) - and don't understand much of electronics, this was a nice background... uh, sorry, - backgruuund watch. Greetings from Latvia.

[@JHNielson4851]

As a former US Navy calibration technician I was happy to some old laboratory equipment brought back to life. I have not seen much HP equipment used for voltage measurement all our HP stuff was signal generators and spectrum analyzers. Fluke was our preferred manufacture for voltage standards. I was wondering were you get you standards calibrated at?

[@shana_dmr]

As additional benefit, now you're well supplied for "neon bulb christmas lights" project. In around 10 years, when you forget the experience of testing them out:)

[@Ranger_Kevin]

Or just send them over to Big Clive, he'll make some funky lights out of them :-)

[@erin19030]

HP made quality sensitive test equipment. I own the 403B AC voltmeter. It's a great-meter for IF alignment on 5 Tube AM radios.

[@joed2392]

Mr Carlson ! Talk about having to " Sing for your Supper " ! You have performed a complete Opera, on this one !!! And every time I see one of your hand drawn schematics, it reminds me of Forrest Mims ! All you would have to do is change to graph paper, instead of regular typing or copier paper !! lol Bye the way, after seeing all the time you've spent on this project. I hope I'm not being to forward by asking, but what's your real day job ?? My guess would be, something like, a Chief Aerospace Engineer with a Phd. in Electronics and Communications !!! Awesome Job as always !!!

[@qzorn4440]

this is a pleasure to watch some legendary equipment being repaired! compared to an WW2 plant where the young electricians state: i cannot fix this old stuff it was made before i was born. so, engineering goes for an costly upgrade with new Rockwell PLCs, HMIs, servo-drives, etc. then, this stuff starts failing after about 6 yrs. so, then it gets replaced with their latest and greatest design and the hardware/software failure cycle starts all over... $ money, money $ as per things working for 20-30 years...real design thanks a lot...:)

[@davidschwarz6877]

I love your videos as always! I happened to notice the Mastercraft Screwdriver set in the background on your bench! Handy set, I own one too!

[@jjrevelry7913]

I am in no way an electronics engineer but just enjoy your films! Given you worked on this meter over time and you were super impressed with the original elegant HP engineers who designed this I wondered (given that I have no engineering knowledge at all) if the design of this HP super sensitive meter was part of your inspiration for the design of your own super sensitive probe which you show on other videos? Separately, though I accept that many of your viewers are very knowledgeable, so may not be interested, I would love to have a film where you actually explain to us, (maybe just me) non-electronics trained but interested folk, how an oscilloscope actually works. I have, having seen you repair a few ‘scopes searched KZbin for a good explanation and not found one which is thorough enough but accessible to those of us (me) who really would need to start from zero knowledge though I have watched loads of your repair films which I really enjoy. From those films I understand some of where you use ‘scopes but not how they work?

[@XGalaxy4U]

It's an optical isolator. For high frequency isolation. I ran across one on the Syncrowave 350 mainboard. Replaced it. They're a few cents to manufacture now. Back then it was a big deal.