HeathBuilt Voltage Reference Source [Restoration]

Restoration Time! Let's bring this electronic device back to life. Lots of interesting facts and examples about power supplies, and component thermal stability explained. This is a HeathBuilt model EUW-16A Voltage Reference Source. Click the SHOW MORE tab below for links.
To learn 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: / mrcarlsonslab
#learnelectronics #[Restoration] #electronics

[@MrCarlsonsLab]

To learn 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

[@Peterjames3535]

Do the test meters add any load to the device while adjusting it.

[@apollorobb]

@@Peterjames3535 The series meters reading current would not but the parallel meter reading output voltage would have a VERY tiny parasitic load

[@timteecvhn]

Then again, there is the fact to consider that... Live and neutral in AC voltage do not matter, as they do not have a specific polarity. So that's probably why the fuse ended up on the neutral instead of the live, because it didn't completely matter which way around it went. So long as the ground went to where it's supposed to go for protection against any current leakage that may find it's way to the case of the device. Still very cool tho to see such an old device.

[@apollorobb]

@@timteecvhn Except for the fact that in most countries Neutral is Bonded to ground and therefore presents a greater shock hazard . If you do not break the live side in switching and fusing

[@foureyedchick]

When I was a young girl, my daddy bought me Heathkits to build every Christmas. I remember the Heathkit LOGO! The shape of the logo and style of the lettering is the same as Heathbuilt. But, I never received a Heathbuilt.

[@Thesignalpath]

Thanks for not having mid-way advertisement enabled on your videos. And nice work as always.

[@electronicengineer]

Great seeing you here also Shariar!

[@DaleDix]

KZbin are making it mandatory soon. They can opt out at the moment though. Advertisers wanted it because nobody watches the ones at the end.

[@paulstringer7083]

These videos do have ads

[@mapleacrefarm]

My dad worked for Heath for 32 years when I was growing up. Thanks for the memories. The iconic color and design of the metal case really takes me back.

[@peterthompson1922]

I have been both professionally and as a hobby after hours devoting my life to electronics. This is by far the most accurate, detailed and educational electronics channel I have ever had the privilege of watching. The knowledge and professional approach taken in every video exceeds any formal training I have had over the years. I want to thank you for sharing your knowledge. What is being taught by you far exceeds anything close and to provide this to our future generations means more than words can express. Once again thank you so much for sharing your knowledge. Kia kaha. I worked for the Australian government designing and managing projects up to 66kV and the attitude is a "she'll be right" and "cover your ass". This is another reason why I respect and appreciate your professional and safe approach.

[@MrCarlsonsLab]

Thank You for your kind comment Peter!

[@RodBeauvex]

He's Canada's perfect answer to Dave Jones. :D

[@jimdavis6833]

At 80 I'm a tad older than you, Paul. I assembled 9 Heathkits between 1972 and the mid 80s. GR-900, GR-2001, IO-30, IO-4205, IO-4550, IT-28, IO-4505, IT-21 & an IT-3120. I miss those days.

[@tomking6006]

I've been quite depressed recently and I can honestly say that seeing this notification has given me the first genuine moment of excitement I've felt for a long time.

[@donaldhoot7741]

LOL.

[@waynethompson8416]

Tom, I feel your pain!!! There are about 5-6 KZbin Channels that I especially love to watch, this being one of them. Lately it has been months between uploads and I really miss seeing new uploads that use to be much more frequent...at least "someone" would put something up every week...now, well, as I said, it can be months and none of the 82 channels I have subscribed to show anything new. Just in case you might be interested, some of the channels I have subscribed to are: David Tipton Electronics Old and New Back To The Future Radios D-Lab Electronics Nick Zammeti I think that you will enjoy at least a couple of those.

[@MattyEngland]

THC is the answer

[@FluxCondenser]

Hang in there, Tom. Hope you feel better.

[@StewartMarkley]

It is so enjoyable to see Heath gear brought back to life especially by someone as careful and smart as Mr. Carlson. I built many kits back in the 60s, 70s and 80s including my first color TV and computer as well as lots of test equipment. Love these videos.

[@me3333]

It's amazing how easy it is to let the smoke out of a component and so incredibly hard it is to get the smoke back into the device

[@allthegearnoidea6752]

LOL well said!

[@doctorjohn-burgtekie]

Like the sound of when those mechanical switches snap into position making a good connection.

[@jerrygeorgopolis8015]

The good old Heathkit days ! Always looked forward to their catalog back in the day.

[@aserta]

If you're afraid of slipping screwdrivers over paint, just get yourself one of those sheets of plastic they use in binders, the thicker the better, and drill a few holes of various sizes at a decent distance. You lay the sheet over the screw you want to remove and it will protect the paint. :)

[@electronicengineer]

That's a great idea! Thanks for sharing.

[@NiHaoMike64]

Or 3D print a collar to keep the screwdriver on the screw.

[@electronicengineer]

@@NiHaoMike64 Assuming one has access to a three dimensional printer.

[@Roy_Tellason]

Or get a screwdriver that's accurately sized for the screw. I like my Snap-On for this. :-)

[@larrybud]

I'm 53, when I was about 7 or 8, my dad bought a heathkit color tv (with remote!!) and built it in the basement. I remember watching him solder the components in and putting the whole thing together. We had that TV a LONG time. You had to tune each channel separately with jumper wires and tuning capacitor. It would drift out every once in a while, but the side panel would pull forward for "easy access".

[@TheoSmith249]

Was it the GR 2000? What a fun project

[@larrybud]

@@TheoSmith249 you know, I couldn't tell you. I googled that model but tough to tell. Watching him build that and me playing around with the tuning in the side panel really sparked my interest in how things work.

[@larryhuff3383]

Years ago I made some service testers for our subsidiary in the US. I used Robertson screws to secure the case. In order to calibrate the device the case had to be removed. I got a call from the technician asking me what I was thinking! He had to drive over to Sarnia to get a screwdriver at Canadian Tire to take the unit apart. Seeing your Mastercraft screwdriver made me think of it. There are some good ideas that have come from Canada!

[@deadfreightwest5956]

"Not bad for something from the 1960s." Hey, that was the Space Age! Anything was possible then. Even me!

[@chrisandrus2735]

Electronics were so beautiful back then!! I especially love the color and look of this one!!😍

[@GrandsonofKong]

Always nice to see gear brought back to prime condition by Mr. Carlson!!! Would see these show-up on EBay now and then. I recall Heathkit made a Scope Calibrator if my fuzzy logic brain is serving me correctly today.

[@medaturbo9899]

Thank you...Mr Carlson's Lab

[@MrCarlsonsLab]

You're welcome!

[@frankowalker4662]

Perfect callibration, Mr Carlson.

[@douggale5962]

Wow, you calibrated it perfectly.

[@allthegearnoidea6752]

Thanks Paul very interesting and educational. Regards Chris

[@qzorn4440]

1968 as a high school kid living on a farm before online, Heath and Radio Shack did serve a great learning service... thanks a lot...:) interesting lecture...

[@FluxCondenser]

Paul, you do such good work and you’re an inspiration to do things the right way. I appreciate the tip about the Spragues.

[@MrCarlsonsLab]

Thanks 👍

[@Frankowillo]

I was just perusing a Heathkit catalogue from the 1950's. Man, that stuff was expensive. The average American might have been able to afford them, but not not so much the rest of us.

[@jasontaranto6359]

Hi Paul, Always happy to see the different and interesting projects that get restored.

[@mikepettengill2706]

Your depth of knowledge is mind-blowing!

[@Electronics-Rocks]

I remember fixing things like this covering the unit with a couple towels to recreate the cover on with my probes still in. Nice to see this kit still being repaired sympathetically

[@wktodd]

Thumbs up for no mid-roll ads.

[@stridermt2k]

I loved seeing the interlock action. -and when the meter slammed to 95 volts -wonderful. Congrats and thank you for another nice journey.

[@tallperson9422]

Another way to pass some time and learn something. More please.

[@billharris6886]

Here is a tip on the rotary switches to add to your bag of tricks. Some of those swirches require such high torque to turn the knob, the unreinforced knobs can easily crack. Also, if you do lots of repetitive tests where you are continually rotating the stiff switch, it can make your fingers sore. So, as a fix, you stretch the spring slightly that holds the ball bearing in place, which can substantially reduces the torque. You have to be careful though and do small scale spring stretching (careful trial and error). This is because, it is like trimming an antenna, if you over-do the stretching, you can't undo it. If you are not careful, you will wind up with a rotary switch that has almost no detent feel.

[@brianspriggs7881]

Thank you for showing this Heath Built kit. It brought me back to the sixties /seventies when I assembled several Heathkit products. Finishing my Heath builds with an oscilloscope. Wish I had kept them but as frequencies began to surpass my ability to view them, i had to purchase higher frequency scopes and function generators! Really appreciate your channel!

[@MrCarlsonsLab]

Thanks for your kind comment Brian!

[@fredmitchel1236]

Good job Mr. CARLSON. You stayed with it. Heath did a good job in their resistor matching. Amazing how good it was without feedback. Say at 100.00 VDC and you loaded 2 mA on the output by using a 50 kohm ...how much would voltage would the output drop? Perhaps Heathkit intend to use it like a std. cell...where you place a sensitive meter between your Heathkit reference...and the unknown voltage...then adjust the Heathkit to a null..which means no error current across⅞your Heathkit and the unknown DC voltage...then read the dials...to determine your unknown voltage. Nice handheld meters....I had no idea TEK made little DVMs.. I will eventually do some Patreon...and help support your cause. Keep up the good work. If I was assigned the construction of a 0 to 100 VDC reference..it would be totally different. ...

[@mackfisher4487]

You are a great reference source, Mr. Carlson

[@MrCarlsonsLab]

I see what you did there :^)

[@newandoldtech5634]

First. Gaining knowledge. Amplified by skill and enthusiam

[@OleF112]

Nice Heath oldie, Paul. As Tom wrote down below, the notification on my cellphone made my day, could not wait to come home from work. 73 de Ole, Cologne

[@bryandavis6229]

Its so funny your doing this, A friend of mine just gave me a whole bunch of the Heath Kit equipment, Spent all day moving it to my house and all of mine works!!! Love the video's!

[@JxH]

@36m about stability. Don't forget that in the 1960s, meters had needles, not 3.5 or more LCD digits. So 1% was probably the target. That's one volt in 100. I know you know, I'm just making it explicit for those following along at home. :-) 73

[@EricTViking]

Good point, easy to forget that 👍

[@city_hawk]

I really like your radio videos. I love when you do old test equipment. Your videos are top notch. Great work

[@MrCarlsonsLab]

Thank you very much!

[@davidwalle5025]

good project. Good did a video on regulator tubes and showed they more stable than zener diodes. You are proved right again.

[@vjdav6872]

so cool. thanks mr. carlson!

[@MrCarlsonsLab]

My pleasure!

[@GraemePayne1967Marine]

Thank you for the reminder about the need to replace the old capacitors! I have an old EICO DC VTVM that my father-in-law built from a kit in, I think, the 1960's. Note to self: order new capacitors before turning it on!

[@billharris6886]

Hi Paul, I just stumbled upon this video (I don't understand KZbin's algorithm) and was surprised at the number of glaring design errors with this Heath product. I don't know exactly when this voltage reference was designed, I suspect the mid 1960's. Zener characteristics were well understood at that time so, the designer was likely fresh out of school. The 100 volt zener was probably used as a simple way to get a 100 volt output. However, (as you mentioned) zeners at this high voltage breakdown are super temperature sensitive, so much so, that the part would actually make a good temperature sensor. There are 3 zener breakdown voltages that have zero temperature drift if they are fed a specific current: 4.7V @ 10mA, 5.1V @ 1 mA, and 5.6V @ 100uA. If you feed the zener with a constant current source, you have a precision voltage reference (although the current will need to be tweaked slightly to optimize the zero drift). Thanks Paul for another interesting video.

[@stefangies5570]

Excellent explained ! Very good video ! A+++++++++

[@jackgott4005]

Hey, Long time fan here. I noticed your discussion on the line chord and polarity are right on. One thing you did not mention is to put the black line lead into the back of the fuse holder rather than the side lug of the holder. This, as you well know is quite important. it prevents the exposure of the hot line lead while replacing the fuse. Great video, as usual. Thank you.

[@PurityVendetta]

Another fab video. I love these examinations of test equipment as my own bench is slowly coming together thanks to your help Me Carlson. Thanks.

[@MrCarlsonsLab]

Glad to help Sophie!

[@jtveg]

Great work. ✔️💯🏆 Thanks so much for sharing. 😉👌🏼

[@muxallopeniot9194]

I like when you do antique projects. You can tell you put a lot of time into this video. So I'm glad it was successful finish for you. Great video until next time.

[@hestheMaster]

Ah, the EUW-16A. The later version was known as EUW-16 . It sold for $65 US in the 1966 catalog. Sprague "Black Beauties" was their trade name for the Di-Film caps. Rule of thumb on bumble bee caps lettering : if it's in red go ahead. Yellow is too mellow( replace) and white(replace) it's not right! Always remembered that!

[@DeputatKaktus]

"Those are some pretty screwy-looking MOSFETs...." Hold up....did you just...? This made me laugh harder than it should have.

[@michaelcalvin42]

The comment about having a very low on resistance killed me too.

[@maxeadrianarodrigues8493]

I am from Brasil, south of Minas Gerais state (200 km of Rio). I love your vídeos! Very, very goods! Your channel is top! 😍😍😍

[@MrCarlsonsLab]

Thanks for your kind comment Adriana!

[@ghost_control3276]

Great audio and visual quality in the video good sir! Love ur content! Keep it coming! Thnk u!

[@johnmorris9711]

thanks fo all the good videos, i'd like to ad a bit on a voltage standard for extremely accurate calibration of up to 1.5 volts DC... this comes from the cal lab at Systron Donner inertial guidance in the late 60s...i was a technician in the engineering dept there from 66 to 69. we were working with analog output from accelerometers and this required extremely accurate measurement of dc up to 7 volts....we had lots of fluke dc meters that required frequent cal checks.... our master volt meter was of unknown brand and it filled a box the size and shape of a coffin and was on a roll around stand...once per month our leader would grab a fresh D cel (zink carbon) and solder a 1k resistor across it then drop it in his coat pocket and head for the UC Berkley electronics dept where he measured it's voltage (about an hour drive each direction)...upon return he would read the voltage on the master ...that zinc carbon maintained accurate enough voltage with it,s 1.6 milivolt load to do that in picovolts

[@MrCarlsonsLab]

Thanks for taking the time to write, and sharing your story John!

[@graemebrumfitt6668]

The colour of that device is gorge Mr C, great repair n tune up. TFS, G :)

[@Internutt2023]

Thank you for your hard work and detail on this and all of your other videos. One thing you should discuss is, whenever getting a "new to you" item to work on, it is best to resist turning ANY switch or knob positions until you check the inside of the unit out as well as possible. I purchased a Heathkit IT-1121 transistor curve tracer last year, and when unboxing it I noticed a slight rattling noise of something inside of it. After I opened it, I noticed a few pieces of brown plastic loose inside the unit, and looking very closely I discovered a broken wafer on one of the 9 position rotary switches, and a slight bend to the outside knob mounted to that shaft as well ( probably caused by someone dropping something heavy on that on switch knob/shaft) . If i operated that switch before looking, I may have done more damage to the unit, and god forbid I powered it and cycled it, as I think it was the switch that set the sweep voltage, and also the position that raised it to 200 volts! A small amount of time and patience at the beginning of a repair / restoration project can save hours of time and frustration later, as I could have shorted out and burned secondary windings in the transformer in that unit and turned a restoration into a "parts only" purchase.

[@montygore]

Very very nice informative video

[@BearStar1]

I have assembled a lot of different Heathkits, mostly TMDE and some table clock radios, etc; Built several Multimeters , D.C. Power Supplies and Signal Tracers & Signal Generators .Sure do miss building those Heathkits ! Wish they would bring them back !!!

[@aserta]

First picture, without any googling, without having a clue of HeathBuilt, i already knew that had to be some kind of school thing. And i'm European. Heh, has to show that when it came to that era, these things were universal.

[@jptucsonaz8503]

Hmmm... As you mentioned about the Calibration & heating due to the cover being off; I would have did the mod. to add two sets of banana jacks & switches on the back; switch on for operation; & off with test leads inserted during calibration. Which is exactly what I did back in the day when I worked at Heathkit! We had to recheck & verify the cal. once a week. We also never turned it off as it took at least 2 hours to stabilize. Of course with today's modern designs, a reference can be on & stabilized in about 5 minutes. Great job! By the way, wish we had that capacitor tester back in the day! It would have made life so much easier!!!

[@jimdavis6833]

Then he would need to move the jumpers to an external point so they also would be accessible for removal and reinstall with case on.

[@jptucsonaz8503]

@@jimdavis6833 Yes, Jim, that is what the switches are for! Switch on (closed) - for operation; when you open the switch (off), then you can calibrate it. Actually, you would normally use a double-pole, single throw for both since both "jumpers" need to be removed.

[@GraemePayne1967Marine]

RE: "with today's designs, a reference can be on and stabilized in 5 minutes" ... I would give a qualified agreement to that. It's probably true for 99% of electronic equipment. However, there are still some devices that should remain on for their reference voltages to be stable. A couple of examples are: * timebase units with very high stability oscillators, such as Cesium and Rubidium frequency standards; * LASER systems used for precision dimensional measurements, and * electronic DC Voltage references, typically used to replace Weston Standard Cells. In these cases it is good measurement practice to regularly measure and record the relevant outputs, and analyze them to detect any non-random changes that may indicate a potential problem. Even the Weston Standard Cells required a stable power source to power the their typical temperature-controlled enclosures. In September 1989 I was transporting a group of standard cells from the Washington (DC) Navy Yard, where they had been calibrated, to where I worked at the Electronic Standards Calibration Lab at Charleston (SC) Naval Shipyard. That trip was interrupted by a bit of heavy weather known as Hurricane Hugo. At a stop on my route I bought a portable AC power generator to provide power to those units for a week until power was restored to the lab. (I also used it to power essential items at home, for a couple of weeks.) The Navy happily (partially) reimbursed me for the generator, because it meant we could restart DC calibrations several weeks earlier than would otherwise have been possible had the standard cells needed to re-stabilize and be re-characterised.

[@johnnytoobad7785]

I built a few Heath-Kits (back in the day). I retired (or gave away) most of the equipment except for the bench FET-multimeter and AC Voltmeter...which I still use. Both have very nice pure analog displays.

[@bergarteric5713]

Good evening Mister This item si beautiful !!! i remember when i was young i have a similar reference voltage ...The schematic was in a magazine " radio plans " very famous in my country ( France in 60 's and 70 ' s) . Thanks for the share and your work .

[@jontallman3878]

Dang, your shop is an electronics candy store!! My dad and I built several Heath kit projects.

[@richardtwyning]

No, in the UK it's "low mileage" too. Luckily we have a moat that saves our important units of measurement 😁

[@l3p3]

It was a joke. :P

[@deadfreightwest5956]

I always laugh at the metriarchs who ask what a foot is. I reply, "you have two, haven't you noticed?"

[@sa8die]

did i hear "moat?" harry potter in tha house!!! (or metric eq. of a domicile).

[@richardtwyning]

@@sa8die better known as The English Channel 😆

[@iNerdier]

Richard Twyning La Manche!

[@grahambambrook313]

It's still 'miles' in the UK, Paul!! :-)

[@rthefish]

The History Guy chanel did a vid about the Robertson screw

[@russnixon6020]

"Screwy looking MOSFETs"; I saw what you did there!

[@deadfreightwest5956]

We need a thread on those MosFets!

[@InssiAjaton]

I recall how somebody (possibly Philips) published an application note with a description of a highly stable voltage reference source.. I have forgotten the exact details, but it covered the temperature effect on zener diodes (less than 5.1 V (negative temperature coefficient) and avalanche diodes (above 5.1 V) that have a positive temperature coefficient. They played the current induced change and temperature induced change of different devices against each other and got their desired stability. Also old discrete transistor based power supplies had a 6.8 V avalanche diode on the emitter of an NPN transistor for balancing. The transistor base-emitter voltage has a negative temperature coefficient of nearly same as the avalanche diode positive constant, so the net effect is a fairly good compensation. Then the semiconductor industry came up with the hybrid reference diodes that had one or more ordinary diodes and a selected avalanche diode in series within the same package. An example was the 1N825 (or 1N8270 reference diodes with 6.2 V. They were very well compensated, but only at one particular current. There were articles in trade magazines about how to get a great 10 V reference with such a device and one operational amplifier.. Feeding the 7.5 mA current from the amplifier output to the 1N825 through a good stable resistor you got all the desired conditions. You got a stable 7.5 mA with a (10.0 V - 6.2 V) / 7.5 mA = 506 ohm fixed resistor. Much simpler than the temperature chamber trimmed combination. I used the 1N825 a few times with this kind of circuit. Later on, when the prices came down, I saw somebody else using the slightly better, but originally more expensive 1N827. Since those days, both buried zener and bandgap based reference ICs have made those early circuits obsolete.

[@johncoops6897]

A trick to fix those knobs.... strip some solid copper wire. Remove the existing grub screw and glue the crack closed. Next, wind copper wire around inside to create a "ferrule" - this may need to be two "rings" to keep away from the grub screw hole. Finally, fill the gaps between wire and plastic with the old "baking powder and super glue" trick. Care is needed to keep the grub screw hole 100% clear.

[@DonDegidio]

Hi Paul, First time I've seen any HeathBuilt. I know you could have some of their kits pre-assembled, but I always enjoyed building their kits. Stay safe. 73 WJ3U

[@GraemePayne1967Marine]

Robertson head screws are gaining traction in the USA, especially in the electrical industry. I discovered I needed to buy a couple of sizes of Robertson drivers a couple of years ago, when i was doing the electrical installation of my new woodworking shop. Those, Torx drive heads, and even Pozidrive heads are so much nicer than Plillips heads. Whenever someone complains to me about a Phillips head driver camming out, I smile & remind them that it is exactly what they were designed to do!

[@TheoSmith249]

They were color coded. Yellow, Green, Red, Black Smallest to largest.

[@jimmyhillgren7479]

Really nice video with good information on capacitors and that you informed about the thermal sensitivity of the zener diode, not many think about that until they actually notice it for real. Also so nice to see a plastic trim screwdriver. Though I noticed you did not use it when you aligned as it looked like a normal screwdriver.

[@grilnam9945]

It’s low mileage in the UK too. :) also I was thinking if those knobs are all identical in size it could be the broken ones broke somewhere else on the device and got swapped around.

[@TheDefpom]

I’ve found the switches on this old Heath gear that the switch shaft gums up, stick some Deoxit on the shafts and they get a LOT better.

[@GraemePayne1967Marine]

Another product we used to use on switch contacts was Cramolin, some type of light oil. I have no idea if it still exists.

[@thefloop2813]

Somehow, by the grace of the gods, about an hour away in Oak Ridge, TN. There still exists, an open electronic component supply store with attached Wearhouse. They are about 20 mins from ORNL (the atomic national research laboratory) so i've always assumed that had something to do with them being able to stay open so long into the 21st century.

[@MrCarlsonsLab]

That sure would be nice to have close by!

[@thefloop2813]

@@MrCarlsonsLab I think it's really cool you actually read and reply to comments so often, and even on old videos. KZbinrs like you are getting very rare these days.

[@mushroomsamba82]

33:35 lovely picture there for DMM aficionados

[@gregorythomas333]

Pretty nice build...and I love the very clicky switches :) I was surprised that you didn't test the polarity reverse switch just to confirm it is working properly though.

[@GraemePayne1967Marine]

I used a lot of Heath educational equipment when I was going through an apprenticeship in electronics in the early 1980s. Another Heath product line was the Heath/Zenith line of desktop personal computers in th 1980's. I had lots of memories with those things. (The computers were actually OK for the time. The users ... not so much.)

[@hotpuppy1]

If there is enough meat in the interior of the knobs, why not machine a brass sleeve to go inside? Super glue will be a temporary fix. If it doesn't crack in the same place, it will close by.

[@richardtwyning]

Fill 'em with Sugru?

[@deadfreightwest5956]

Or, align them and remove the screw, insert a drill, and drill a divot into the shaft. The screw will just have to rest in that divot, with a minimum of pressure.

[@vancouverman4313]

You can buy over the shelf very similar black knobs in many electronic's parts stores today. The only difference would be the circular design on the top would be missing.

[@oldenslo4141]

I enjoy your video but most of the time I don't understand what you are talking about, that's ok. As a kid, I remember helping my dad build a Heathkit stereo amp and a separate tuner. I think he liked me to look at the little bands on the transistors to match the sets together. I also had a Heathkit guitar amp that we bought many years ago that would handle bass guitar as well. Thank you.

[@derstrom8]

I once had a HeathBuilt sine/square wave audio signal generator, so I am familiar with the company. Very similar in style to this voltage reference.

[@MagnaRyuuDesigns]

Being from Wisconsin, Robertson Screws are familiar to me. Many of old sheds in backyards and on farms seem to always have a mason jar of them LOL

[@TheoSmith249]

I grew up 10 minutes away from the Roberston screw factory. My neighbour worked there,

[@gacherumburu9958]

👍👍

[@winstonsmith478]

That's in amazing, like new condition. Very lucky considering the usual engraving tool and sloppy label school and lab environments.

[@ronniepirtlejr2606]

Wow, that thing is beautiful for it age. It's older than me lol 1970. They don't make things this good anyone! We are better off rebuilding older electronics, maybe upgrading a few components if needed & enjoy using them for a long lifetime!

[@wayneparris3439]

The Robertson screw and driver could have been bigger than the Philips but Mr Robertson wanted to make it all.. When Ford wanted to use Robertson screws to assemble their cars in the U.S. (in CA Robertsons were already in use) Ford wanted to make the screws and drivers but Robertson wanted to make everything and sell them. They could not reach a deal so Ford went with Phillips and the rest is history. Robertsons are still very popular in CA and are just now starting to show up in the U.S. markets. For warming the unit up when calibrating, I think I might have been tempted to run jumper leads out the slots in the back of the case that were attached to the test points inside, just to provide access while having the unit as close as possible to its operating condition. Clearly though, that wasn't needed as the results came out great anyway. Just me overthinking things, nevermind :P

[@macchina1969]

Hey! Another fantastic video! Great job. One question: which type of superglue are you using?

[@danm3188]

Hehe... rare Mr. Carlson humor @ 5:45

[@sparkyprojects]

I know the diagram shows switch and fuse in different sides of the mains, but i prefer the switch to be in the hot, followed by the fuse, the neutral should be direct to the transformer. Something like a couple of jacks with break contacts would be useful for calibration, but how often would a hobbyist do that. I guess you could run the wires out the vent so the cover could be closed during calibration, then remove the wires after. One thing i've done in the past is to insert a screwdriver under the wafer switch spring and gently twist to reduce the tension, this will help with not breaking the knobs, but don't overdo it.

[@1959Berre]

@ Glen Watkins The unit "Farad" is named after Michael Faraday. So, the emphasis should be on the 1st syllable. Paul does it differently.

[@macswanton9622]

All the thumbs up appear to be the same size, or mine would be bigger

[@Electronics-Rocks]

Thanks for no mid way Advert

[@alan_wood]

Nice video but, blimey, you sure sent me down the rabbit hole of screw head research!

[@So-Flo]

Great video, very interesting. P.S. we use miles here in the UK. It's the rest of the Europeans that insist on kilometers

[@SubTroppo]

And more pertinently valves instead of tubes. See Franlab for 1950's HIVAC square section valves in a German built "spy" wire recorder. ps Anytime I see Heath Kit, "Heath Robinson"* springs to mind, so in the UK you probably would be wise not include"Heath" in branding of anything even a little complicated. *Rube Goldberg in the US

[@Richardincancale]

Putting some cling film over a unit that you have to run with the cover off can be effective in getting the airflow to be the way it’s meant to be, and stabilise the temperature for alignment.

[@andydelle4509]

Note the original two wire line cord on the schematic. And likely for good reason. On a precision signal or voltage source, you would not want ground loops.

[@jeremiahhollowell8994]

Awesome video as always.. any have any idea where I could find information on a GE two way radio.. the model number I found is not showing up on the web. I know it's from the 40s.

[@OC35]

Never seen HeathBuilt units in the UK. You could buy ready built units, a friend of mine had a part time job building kits for Heath.

[@anthonymigliori4703]

When I repair plastic I use the old baking soda and superglue trick. It dose work but you have to work quickly. And have small files around to file ot down after it sets up. This is how I repaired my zerolemon cases that kept breaking on my note 9. And I will now use this trick on other plastic things. The trick I found is to use the least amount of baking soda so it dose not enlarge what you are reparing. Unless its completing missing a chunk of plastic. And then you can spray paint it or just permeate marker it.

[@umageddon]

+1 for robinson screws

[@basinstreetdesign5206]

Robertson

[@rimmersbryggeri]

That thing would look great with chickenhead knobs.

[@johnbrowne3518]

"Gullwing" knobs like the ones used on the Tx/Rx switch on the "Benton Harbor lunchboxes". heheheh

[@andrewstewart8704]

Hi from Sydney, Australia Mr. Carlson 😊 I love all of your videos! Do you repair SMD circuits? I would like to see you make such a video.

[@MrCarlsonsLab]

Hi Andrew, I have designed many SMD circuits. I just released another design on Patreon that uses SMD parts. This was built with the majority being 1206, but I have many designs down at 0402 as well.

[@andrewstewart8704]

@@MrCarlsonsLab Fantastic! Your skills and talents are truly amazing! I learned some basic electronics from my father whom worked at Qantas way back when the transition from valves/vacuum tubes to solid state was going on. My father got the job by drawing the circuit diagram of a Williamson valve amplifier from his memory. I have been learning many things from your videos and always excited to see a new notification from your chanel. I, and many others would have to say that your very generous and much appreciated contribution the youtube electronics world is amazing! Many thanks for what you do 😊

[@PKhanz]

😍