Bizarre Circuit Tests Capacitors with RF! 

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Dear Paul you seem to be worried about boring us, but you could make a 4 hour video on the schematic alone and I would eat it like candy.

I love the long schematic explanations, I learn so much!

Mr. Carlson, two observations. I had no interest whatsoever in this capacitor tester, yet I found myself glued to the video and unable to stop watching till the end. Fantastic job. Second, my three year old watching beside me said "that's nice dada, can we watch another one?" LOL

Great information, as always. Your effort in making these videos is much appreciated.

Long explanations are AWESOME provided the information is presented efficiently and not repeated. Even so, the dual timeline or "skip this" button or even just putting the longer explanation at the end is a good way to meet everyone's preference. I LOVE that you take the time to explain lots of detail. Great video again, Paul. Thanks!

Those 48 min and 50 seconds just flew buy, your electronics skills are only matched by your skills for passing information on to others . Just fantastic stuff.

Mr. Carlson. It's a privilege. You're by far hosting the best, the most competent and comprehensive walk-through into the world of electronics. Being a bit senior to your age, it's comforting to know such bright and intelligent young humanoids are in existence for years to come. My hat's off to you. My wish for an upcoming episode would be, if you could show where and why tantalums and polypropylene caps could be a better choice in video circuitry (S-VHS/LaserDisc), by replacing electrolytics in the RF signal path. Why are they a better choice ?

In a real world, this is what "reality TV" would be.

Definitely want to see the RF stuff. Enjoyed the schematics.

Yes please explain the schematic. It would be very educational for me!!!

I love how you mention little tips and tricks along the way! Like with the screwdriver, the kilo-megacycles etc. Great stuff, Paul! Thanks for sharing!

lengthy explanations for small circuits are very welcome

That device is ingenious Paul. Great video.

At 40 MHz, the wavelength is about 7.50 m where a quarter of it would be 1.875 m, though the cabling does not seem are so long. Please give details of the circuit analysis in your videos. This has great educational value for most of the viewers as they can learn how to apply them in their own cases. Many thanks for your video.

That schematic needs an entire mathematical representation for sure! LCR fed oscillator to find capacitance on a voltage grid dependent to ground.... ??? That isn't bizarre to me, its beautiful! Thank you for taking the time to share with us all. I wish I was monetarily wealthy I would certainly flip you some coin. All I can say is thank you for helping to teach me and think about new possibilities of EE.

Would definitely enjoy a session on detailed schematic explanations as well.

Your construction of the 40" cable and minigator clips was great. I just wish i had that info 40 years ago in the service. All of the different coaxial cables with a multitude of center dielectric insulation was crazy. The worst part was soldering the center pins of the RF connectors without melting the insulation inside of an aircraft when it is 5 below zero.

As always Paul, one huge thumbs-up. Count me in with the rest of the chaps who request maximum tear-down circuit detail …with maths included where appropriate please. Thank you, Phil.

I'm happy to have found this video. I recently aquired a Midland 23-170 capacitor tester and haven't had any luck finding schematics for it. Turns out, the Midland's circuitry is nearly identical to the unit in this video. Thank you from an aspiring electrical engineering student.

The expanded schematic explanations are great tutorials and are really appreciated and valued. Thank you! Fred

Mark me down as one who would like to see each component explained and what it does in circuit. Great videos you put out, please keep them coming no matter how long they are+.

At first I thought to myself.... who gives six fox about this simple thing. Especially when Mr. Carlson himself invented a much better cap tester, and its low voltage. But then after watching this video. I learned a few things after all. So far, as a matter of fact, I have learned something in every single one of Mr. Carlson's videos. Well worth watching.

I'd absolutely love to see an RF explanation video. I'm an EE student and I love watching your videos and love getting to learn the new things you teach with them. Learning about RF stuff with your videos would be a joy!

For anyone interested in acquiring one of these testers, I was able to pick up a Mercury model 1400 capacitor tester at a swap meet. (Mine is not for sale.) It seems to be factory wired and the circuit, functions, tubes (British and German), dials and switches are identical to the Paco C-25, although the parts layout on the chassis is different. Also, no parts needed replacement. I was similarly surprised at the circuit diagram. I kept looking for a rectifier and electrolytics. I was wondering how one could feed AC straight into the plate of a tube and get it to do anything. Great video and explanation. It ended a lot of my head scratching.

YES! If you could do a full explanation of the schematics that would be AWESOME!!!! I watch all of your videos because they are SO informative and I have been learning a lot from you. This is my first year as an Industrial Maintenance Technician and I have to do a lot of trouble shooting at work when one of our machines goes down so I really enjoy watching your trouble shooting and repair videos. I love your videos please keep them coming! And I would love to watch any full length explanations on the schematics! I can't tell you how many times I have gotten an "AH-HA" moment and a light comes on in my brain when you explain something and it makes sense and all comes together.

Entire circuit explanation idea is great! Thanks for your vintage videos.

Ingenious! Another nice video, Mr Carlson. That is a neat circuit in the old Paco tester. Some scum broke into my tuck, and ran off with my $400 Klein leather tool roll, so away went $5000+ in tools, and $20,000 in radio equipment. I bought a new Fluke 87 V, and a monster Fluke clamp on. I found my Amprobe ??? Model true RMS AC only peak hold clamp on. I had been doing home inspections for my new home/shop, and lost a thermal imaging camera, clamp on ammeters, volt meters, circuit tracers, moisture meters, thermometers, and mostly other tools for some roadside repairs. I did NOT have my $400 Brownell's screwdriver tip set, which is worth every penny. They are all hollow ground, and there are 75 + 12 different sized slot head tips alone, so they grab those old slot screws really well. I need a new alignment tool set. Those get chewed up over the years. I also need some more replacement electrician's tools. A few items turned up in the lawn between my truck, and the neighbor's house. His son just got out of prison too. You can guess why he was in prison. Burglary, theft, robbery, shoplifting, and drug charges. I think my Sano amp's reverb runs off a 6C4. I have a lot of nice tube testers. One runs a 5KHz signal through the tube under test.

Excellent! The detail is appreciated... I just bought a Paco C-25 today!

Hey there Paul , I would like too see full explanation of simple schematics such as this , because it makes it easier to understand and prepare us for more complicated schematics and there understanding ! I think a lot of us feel a little overwhelmed when looking at very complicated schematics because we don't have a primary knowledge of how to read them or the paths of the circuits we are looking at ! I know that this would help me understand what I am seeing on the schematics and the equipment being worked on ! Thank you so much for all that you do for all of us that want too understand the electronic world that we live in !

The conversation of the 1/4 wavelength stub reminded me of using an SWR meter on my CB antenna years ago. Great video and explanation.

You have a very soothing voice. I would enjoy long form and deep explanations of schematics, I think it would lend me a much rounder understanding.

Yes i'd like to hear the circuit description, and analysis. Thanks for another great video.

Super video! Interesting as always. Can't wait for the new video you mentioned!

Bonus fact: That oval shaped hole in the back had multiple uses back in the day, such as having two cables with glands or two DIN sized signal connectors. A really interesting one was that it would also fit a mains input plug based on the traditional European style mains plug, which is really a 19mm double banana with extra insulation. I have even seen a device where the power cable was terminated in a female plug on the back plate, but facing inwards and mating with a power plug on the chassis, so opening the unit would unplug the unit, but a test engineer could override by simply using a regular power extension cord that he would have to remove before closing up the box.

Fantastic intro to 1/4 wave stubs. I bet some people will have a hard time getting their heads around that. I know I did when I was learning. A great learning video. DC4DC

Oh yes, 1/4 wave needs more followup. :) Thats black magic right there.

Paul please do a video on the circuit I personally love the theory that is why I think your so good at explaining stuff thank u in advance

As a boy, I thought the Eye Tube displays on my dad's VM (Voice-of-Music) stereo reel-to-reel tape recorder were the look of the future!

Paul - Thanks for jogging my memory from electronics school more than 40 years ago. I enjoy your videos and have joined you on Patreon. I'm also an Extra Class Ham, but I haven't thought about vacuum tube tech in a long, long time.

Tube schematic explanations are always nice to see, especially in depth ones that get into the math behind the circuit. I have not been able to find a lot of info on tube biasing for example. Nice video as always. Cheers, - Eddy

Hi Paul, excellent episode. Thank you :) Yes please make more in depth videos on RF and analysis of schematics. Cheers, Gillian.

Definitely interested in in-depth discussion of unique circuit designs.

Just watching this now. On your comment about detailed explanation vs short video. I prefer detail. I figure people can skip ahead if they want to skip explanations.

Great video! Love to see the PACO equipment still around. I have my father's Model S-55 scope to restore in the future. I would love to see in-depth schematic explanations as well as in-depth RF circuit.

Very nice explanation of this tester. I really loved the way the alignment procedure was written. Thanks for sharing Paul.

Thnks for your inimitable yet didactic approach!! Easy to follow.

I used to have one of these, I'll have to look and see if it's still in my dad's basement. The open / short test used RF as you explained. I put a scope across the test leads in electrolytic mode and was surprised to see 60 Hz AC (from the filament winding so low voltage). This was 40 years ago at least so I could be wrong! It did look and work exactly as yours. I was always amazed by the lack of the expected power supply components, that got me to take a good look at the schematic as I didn't build the kit. As in "How the heck could *that* work!"

Another great video! looking forward to learning something new

That was terrific Paul. would definitely love a primer on the 1/4 wave stuff and the entire schematic. Might be fun to build something like this. I'm definitely going to keep a lookout for one for sale. Also, a video on just the trick of soldering the alligator pigtails to the wires with the high heat shield would be nice. That sounds brilliant but I couldn't quite picture all of it (like how you get the solder in there once it's covered). Lastly, you touched on "tuning" coils (which I suspect is similar to tuning for coax length) ..I'd be interested in a primer on just that if you don't have one.

I would love to see a video about RF, 1/4-wave vs. 1/2-wave, how coax length affects SWR, what's really going on in an "antenna tuner", etc.. And the icing on the cake would be to have your permission to post it on my little FB group where we try to demystify the complexities of radio for the entry level amateur radio operators. So many want to get involved without understanding that ham radio, at its core, is a hobby of electronics, and so requires some technical understanding. And, of course, it's always good for me to keep refreshing this subject in my mind. Thanks Paul, you're providing a valuable service to us and it is certainly appreciated. 73

Excellent tutorial on an interesting piece of test gear, Paul. It may be too late to offer this suggestion now but, maybe a multi-episode (2 or 3 short videos) on the RF principles and theory then apply to the C-25 tester's operation? Such a neat application for a circuit of this type. Keep up the great work.

Mr. Carlson go in deep with the schematic on this capacitor checker. I relly like your electronics tutorial stuff.

Paul, I just discovered your videos! They have nudged me back into interest in electronics and ham radio. Your videos are what broadcast TV should have become. Well done!

Damn you, Carlson! You’ve got me bidding on eBay again!

WOW, those are really bizarre testers, but also would be very helpful in capacitor short testing.

8:27 Next Christmas get yourself set of electrical screwdrivers. They normally have plastic isolation all the way down to the head. Another great video ! Thanks.

The "click here to skip" approach is imho the best. You will always have some that want to hear it, somet that don't. This way both should be quite happy.

Finally got to watch it. Great information. I always need to time it right, since I want to watch all of it in one go. (Life with family is a constant series of interruptions :) I like the in depth circuit description (idea) and wonder if it would benefit from doing the same scope waveform overlay that you did later on, so the viewers get to see what the waveforms supposed to look like while you explain the circuit details. Could be a handful to edit in afterwards, I have admit.

Thank goodness for the Canadian Robertson screw!

I will never forget the old Eico 950 / 950B. It was basically a wheatstone bridge and amplifier circuit. The indicator tube was a 1629.

I think having a seperate video series on just schematics would be pretty cool, but what do i know, i'm just a nerd! Having the flat diagrams, and explanations / thought process explanation behind them would be good to watch. At least, as a sort of side piece anyway.

I bought an Eico 944 Flyback tester must use the same principle as the capacitor tester you showed here. It has 1 6V6 tube and no electrolitics or paper capacitors​. I enjoy all of your videos.

Nice little trick with the heat insulation tube :) Thanks Mr Carlson!

By all means, please make a video concerning reactance, and inductance Your videos have a very level of knowledge which makes them a pleasure to watch.

Fantastic video!! great work

Awesome video! More RF please.

Thank you very much for this clear, informative video!

Wow that's the sexiest magic eye tube I have seen in many years looks like a Cylon from battle star galactica. Very interesting bit of kit thanks for sharing.

Thanks! I would enjoy more detailed technical videos about rf in circuits as well.

PLEASE do the full schematic explaination :) Maybe for the Patreons? Thank you for the huge effort!

Definitely like the schematic explanations!

I would enjoy seeing a lot of time spent on real detail of schematics in the future !...:)

I really enjoy the in depth schematic discussions that you do. If you have the time, then a video that goes into detail would be welcomed by me. Thanks as always!

All this scematic reading is very interesting, This tube stuff all before my time,

Great video! Loved it. Thanks so much.

Cool stuff here. Very interesting application of reflection.

Great Video! Paul, you know I really like your explanation of schematics. I guess it would be much effort to do this for all schematics with timeline skip etc. in the future. But for some special circuits like in this video I would really like to follow you along to get in detail on every component. Btw: The Paco is a real beauty! Many thanks, Ralf

Hi Paul, you could have used the shrink tubing that looks like a pair of trousers to cover those spliced wires. They are available in different colors.

I remember back in the early 90s Electronics Australia had a kit based around similar idea but solid state to make a cap tester that you could plug into a normal multimeter.

Yes please, Paul. Always good to entirely explain the schematics. I have gotten decent at interpreting them, but I always learn something when you go through them. Deep into RF is always good too! Thanks for sharing.

Suggestion: Perhaps, in the 'Show More' section, you could add a link to the schematic and maintenance suggestions so that we could make it enlargeable on our computers to really get a good look at how the circuits are designed, and WHY they are designed the way they are. You don't have to add the whole users manual, just the pertinent circuit details. That would be very helpful to those of us who really want to understand how these devices operate. Fascinating stuff, LOVING the videos. 73

Another great video and very interesting. Thank you again.

Nice one mr Carlson big thumbs up I really enjoy your videos 👌

my favorite youtube channel when I need to sleep

I would love to see you go into full detail on the RF portion.

Yes, I would enjoy a deep dive into the schematics. May be in a separate video or separate time line. A lot to learn and a lot of fun too. Regards.

Yes for in depth explanations :D

Wow I just got one to figure out why it's in circuit. Thanks for your help

very cool , have never seen one before . will have to look for one.

I enjoy long explanations. So go for it Paul...Jack

Loved everything except the limits of the tester. Since many caps don't short or open but wander from age, environment, or leaking this device would not do much for me. A ESR meter or just a good cap checker with leakage option would be best for me. Thanks again as I did not know you could do all of this with no DC, amazing!

I would absolutely love a far more in-depth description of the RF circuitry and schematics in general! You're videos are such a great source of knowledge!

WOW Mr Carlson...What a Lab...Wish it was mine!

Very clever simple circuit, why go complex if this works well :) And a nice way to connect test probe to the coax, great stuff as usual!

Great presentation as always, one suggestion through. I am a CNC machinist, programmer, and CNC repair. By day however I supplement my weekly (very weekly) pay by repairing amps, cncs and whatever wanders through the door. A segment on what basic test equipment you consider essential would be really cool. For example I have: 2 BK100MHz scopes, BK21900 dig. storage scope, 2-3 crappy cap testers, standby Fluke 111 multi m., HP Spectrum Analyzer 3582A, 2 Tek CFC Func. Gen., BK 2831D True RMS 4.5 dig., Pwr Design TW5005T dual pwr. supply, Fluke 8922AT. RMS vm, 2Tek PS 501s, DC503 ctr, RG 501 ramp gen., PS 503 Pwr Sup., DM 502 DMM, PG502 Pulse Gen., RG501Ramp Gen., DC503A Univ. Ctr. & 1/2 dozen other items. But I need a good Cap tester, which lead me hear. Is this a good start? Machining lead me hear, gives me funny $ to buy test equip.

yes Paul ! count me as one who would be very interested in watching a series on RF.

wow love all the gear in your lab lol

A bit late but, Yes one of the highlites of your teachings is schematic tracing with parts explanations. TY. Very much desired.

This is one of, if not, THE most interesting channel on youtube. The icing on the cake is that Mr Carlson is one of approximately 5 North Americans who can pronounce the word SOLDER correctly. Aside from that, he knows what he's doing. A rare person in this day and age!