#256

[@danmoretti8898]

I can't even fathom that 10 people bothered to thumbs-down this video. Your videos are prime, sir. This channel is altogether the single most thorough, coherent, and successful delivery of practical, working information, certainly re: electronics, and perhaps everything else on YT.

[@w2aew]

You can't please everyone, apparently.

[@jessihawkins9116]

it’s 11 now. 😏

[@clytle374]

​@@jessihawkins9116what is more concerning is that the KZbin algorithm will suggest 100 videos of someone building a so called 500W amplifier with a torch, coat hanger, and a random MOSFET... And not this channel.

[@jessihawkins9116]

@@clytle374 I think I’ve seen that video 🤔

[@clytle374]

@@jessihawkins9116 we've all seen that video, lol

[@stevieboi61]

from knowing nothing bout these things few minutes ago i do now. good job explaining. thanx👍

[@seans9885]

Thank you very much, the most up-to-point, informative, fantastic mini-lecture.

[@alocin110]

Thank you very much for a very informative video. Your explanation is remarkable and with full details. I really watched the whole video without blinking an eye. Your commentary is excellent, very clear voice, very good accent, and very detailed ingredients and comparisons. Thank you so much. it helped me a lot. I liked your video. Sir can you do a vlog with Motor Start and Motor run capacitors? Thanks.

[@MadaraUCHIHA-hy9xe]

You did a great job breaking down this subject, especially the difference between different types

[@AppliedScience]

Great video! Thanks so much for all of the info. I had no idea the marking band on film capacitors indicated the outer foil plate. I was always worried that some film caps were somehow slightly polarized.

[@AppliedScience]

Oops, but now folks in the comments are saying manufacturers no longer mark which terminal is the outer foil, but still put the band marking on the cap! I guess it should be tested electrically for really critical applications.

[@w2aew]

Always humbled to hear that I can help teach you something, Ben!

[@w2aew]

Yeah - Paul at Mr. Carlson's Lab did a good video on that. So much for quality control!

[@Motorman2112]

Mr Carlsons Lab has a very good video about this.

[@whydidyoutubeaddthis]

I enjoy your videos and I tend to suggest them as reference material for both new and senior EEs that work in my group. Excellent stuff.

[@theradiomechanic9625]

You have to be careful with the "orange drop" caps, and many of the film caps, as the band no longer tells you which is the outside foil. This can be tested by using your scope. Connect the cap and hold the body between your fingers and see how much voltage shows on the scope. Then reverse the leads and test again. It is often the case the band is incorrectly marked. The lowest "noise" pickup will happen when the ground lead of the scope is on the outside foil. This can be important in high gain audio amps. Also Tantalum caps throw in the monkey wrench by marking the Positive lead with a band vs aluminum caps which mark the negative lead with a band.

[@MartinPHE]

Yep saw that on Mr. Carlon's Lab

[@jason4547]

LoL @ your attempt to appear relevant. You Insecure people are funny... Hahaha

[@billyray1172]

@@jason4547 The irony 🤦‍♂️

[@jason4547]

@@billyray1172 Jonny the projection

[@tychosis]

It's good to see you back posting instructional videos, sir. I am in system engineering/integration and (honestly) am little more than a glorified technician. I find myself in the company of EEs every day and your videos have helped me sound like I know what I'm talking about. =)

[@dominicgoodwin1147]

Why didn't I get a lecture like this when I was at university? It's just so essential to know all this stuff. Thank you for this.

[@dsvet]

I can't speak to all bu t seems like most professors at Uni. are purely academic and spent little to no time in the field. I believe this guy has spent time in the field as and applications/design engineer.

[@johansvideor]

One way to tell the difference between Polyester and Poplypropylene film capacitors is that PP in general have much higher Q factor. This requires a proper LCR or capacitance meter, though. Common PE caps have typically a Q value of 100 - 200, whereas PP have >1000 or even >10 000, similar to PS caps and Micas. I noticed that cheap CBB (PP) caps that you can buy nowadays on Amazon, Ebay and from China, have the same Q factor as their similarly looking PE counterparts (Q around 200). I don't really know what's up with that. Maybe stick to known brands, especially for higher frequency stuff where Q matters.

[@PixelSchnitzel]

Fantastic video as usual! There are several Part 2 possibilities if you're so inclined. A deeper dive into the electrical characteristics of capacitors is one. I really appreciate your clear teaching style. What a great service to the community!

[@kennyambrose2321]

Your videos are some of the greatest, especially for learning new things that you may not know or reviewing things you may have become rusty on. A lot of my family are in the recycling business and let me go through the electronic circuit boards before they are sent off. One of my finds was an old medical defibrillator machine that contained a 36 microfarad electrolytic cap rated at 5200 volts DC. It has a warning on it in regards to what you were saying about absorption. It warns about recharging back up after being discharged. Another thing that may be interesting to people watching this video has to do with mica capacitors. I worked in mining for many years and would pull off chunks of mica that I would find on the ribs ( side walls ) of some drifts ( tunnels ) and the mica came in sheets almost the same thickness if not the same as the mica insulators used to insulate transistors and other electronic components. made me wonder how those insulators and mica caps were made from this type of mica. Thanks again for your great, informative, and very interesting videos.

[@carlgradolph9676]

Another well researched, thoughtful video, full of practical information. Answers a lot of questions I've had when poking around devices I've torn apart and wondered about.

[@pauludrea4082]

Thank you very much for such a well made presentation. I learn a lot from your videos. All the best, Paul

[@cpopte]

First ... I andomly found something form you while searching around for oscilloscope external trigger problem that I had. Then I randomly watched some other video of yours, after that I liked one of your videos, and made me curious "whats this guy actuall posting...." and clicked on channel's name - videos. Ok....now... after seing your list - I subscribed. I will start to watch everything that I like around here, and I want to thank you for your work. Quite amazing.

[@malcolmholmes115]

Looking forward to play with a bunch of Soviet capacitors soon. Thank you for your videos, you are one of my favorite teachers.

[@wither8]

Nice to see you back making videos Alan. Jim Williams wrote an App Note for LT(#72), which had a subsection on Bypass Caps which is what I would throw into the "must reads" category for anyone doing HF work.

[@w2aew]

Yes, anything that Jim Williams wrote is in the "must read" category - pure analog genius.

[@hubercats]

Thank you for producing this comprehensive and well structured overview of capacitors. Wonderful!

[@christopherdavies5562]

Thank you for posting very informative videos such as this. Your knowledge is amazing. Keep up the good work!

[@edmclaughlin4923]

Thanks Alan. With everything I have fixed, I thought I knew just about everything about capacitors. Getting some of the mixed component boxes from Electronic Goldmine has given me a chance to fool around with every type of capacitor you mentioned. Still you found a way (and always find a way) to introduce some new information in these basic component videos. Thanks again!!!

[@jimadams2473]

Absolutely this is the BEST tutorial on capacitors I have ever seen. Very nice work W2AEW.

[@jesusespeleta617]

Insane amount of respect for all the effort you’ve put in over the years to educate. My only question is where did you learn all of this stuff? For example this video, is this all industry knowledge? Do you browse academic journals in your spare time? Is it just experience and observation from looking at hundreds of capacitor data sheets? I hope to be one day as knowledgable as you are on anything, thanks again.

[@w2aew]

Thank you very much, Jesus. Learning all this "stuff" came from a multitude of sources - ranging from years of working alongside some very smart people, reading a lot of good technical articles and books, studying component datasheets, learning from mentors and a ton of trial, error and experience. You know what they say... "Good judgement comes from experience, and experience comes from bad judgement". All part of being in the engineering environment for nearly 40 years...

[@johnwest7993]

This is the sort of information that turns a noob engineer or tech into an advanced one, one of the steps in ultimately earning the title 'senior'. I've been in the business all my life, but I've already watched this twice for small nuggets I've missed.

[@DeeegerD]

Nice to see you back. You left out the Flux Capacitor?

[@w2aew]

I was too afraid of going back in time!

[@tinygriffy]

also the required 1.21 gigawatt might have been an obstacle

[@SirMo]

Always great to see w2aew publishing a new video! Thanks for this primer on capacitors, very helpful stuff!

[@pnjunction5689]

Very good video, thanks. I didn't know about about the band on the film caps until now. Always good to learn something new. I would also recommend anyone who hasn't already done so, to have a good look at one of the manufacturers application notes on tantalum capacitors before designing them into your circuit. There's a lot to learn about rated voltages, temperatures, failure rates, etc.

[@andrewmullen5770]

Man your videos never cease to amaze me, on a lot of them I will sit there with my notebook and transcribe your note sheets 👍 the way you break down and organize the data really helps me to onboard some of these concepts. Thank you very much for what you do!

[@w2aew]

As you may know, the notes sheets for my videos are usually available as a downloadable PDF file. The link can be found at the bottom of the video description on the KZbin page for each video. For example, the notes from this video are here: www.qsl.net/w2aew/youtube/capacitor_types.pdf

[@rpgquestboard]

This was excellent. Thanks! I've been searching KZbin for a good discussion on the types of caps and none that I've seen have covered this in this detail along with use cases.

[@Edisson.]

Hi, I came across your perfectly shot video about capacitors, you talked about the temperature dependence, but it's a pity that you didn't point out the problem with soldering with polystyrene capacitors, it will permanently change its capacity when the terminals overheat during soldering. At present, it is no longer the case that the mark on the capacitor indicates the outer foil and it is necessary to do a hum test with an oscilloscope to identify it. I have met capacitors marked this way many times and often the outer foil was on the opposite side from the brand. Nice day 🙂Tom

[@richardmills5450]

Another good explanation. I love the PDF notes. I wish more channels included them. cheers

[@Travis141123]

Thanks for the video. As an old/new electronics student, it's nice to see these things explained without too much engineering jargon.

[@wk2w]

Big big big thumbs up!!! You've made some excellent videos, but this one is extremely helpful. It's packed with lots of great information. Can't thank you enough.

[@purza95]

You have answered so many questions I've had about capacitors. Thankyou! Two things I want to mention. My company sent a service memo out stating that they reverse polarized a small rectangular electrolytic cap in production. We had to go into the field and replace them. They would fail after about 5 years. The first one I did I had to remove 32 screws to get to the board!!! I recently bought a very, very expensive ceiling fan with a custom led light. When you turn on the light it hums worse than an amplifier that goes to eleven. I assume this is due to the ceramic caps resonating in the audio range used in the DC to DC converter.

[@cuban9splat]

Thank you for removing a lot of the mystery about the different types of capacitors. Excellent presentation.

[@Bushougoma]

So dielectric absorption is the term. I experienced it first hand years ago I just didn't know what to call it. When I used to work on CRT TVs I found that the anode caps regained some high voltage even after discharging them with a high voltage measuring probe (I was able to monitor the slow discharge on the meter). I would equate it to a nasty static shock more surprising than painful. I only had to get bit once when reinstalling an anode lead. I took a wire and installed alligator clips on each end after removing the anode lead I hooked one end onto the CRTs braided ground strap and the other to the anode cap. I only removed this shorting wire right before I was about to reinstall the anode lead. A CRT is essentially a large capacitor there is a conductive surface on the inside of the tube (one plate) the thick glass (the dielectric) and a conductive surface on the outside the gray aqua dag (the second plate). This wire shorts out this capacitor preventing any "surprises" later :-).

[@w2aew]

Yep - I worked in a TV repair shop in the late 70's, early 80's while in high school - learned all about the 2nd anode and the voltage regrowth!

[@tinygriffy]

most comprehensive capacitor tutorial i have seen so far, very nice, thank you !!!

[@jasonlaverty76]

Excellent. I have a box full of salvaged Caps that you have now identified as Mica caps and I can use these for decoupling in my Audio amplifier projects. Many thanks for helping me in identifying them.

[@w2aew]

I'd be surprised if the mica caps would be large enough in value to be usable for audio frequencies (unless used in very high impedance circuits).

[@elipticolt17]

Great Video thanks for that

[@DAVET38]

Another nice (and useful) video Alan. I found it very informative. It seems I am not the only one who has difficulty identifying the dielectric in the plastic film caps.

[@w2aew]

Very difficult unless you check out the device manufacturers data sheet.

[@DAVET38]

Very true, Alan.

[@romanescu_misha]

You should merge all the knowledge presented in your videos, mix it with the way you present it and then write a book. This would became the top handbook on electronics and radiotechnics.

[@w2aew]

Maybe I'll have the time to do this when I retire...

[@KCLIBURN-mj9qx]

I'd have to have a copy! I watch Alan's videos like I'm back in Basic electricity and electronics.

[@sanjaysethi7033]

Nicely done, mon ami! Brought back old memories … and created a few new ones!!

[@erikisberg3886]

Another really great video! I am a scrounger for mica cap wherever I find them since they lately have become so expensive and hard to source. One current source I found at fairly decent price is the SMD ones from Cornell-Dubilier MC Series. Limited stock has been available at RS components. Used many of the 10pF 1000V 1210 ones with very good results.

[@mikesradiorepair]

Excellent overview of capacitor basics. As Vern noted, the band on many modern film caps no longer accurately represents the outer foil. Paul did a very good video on demonstrating this and how to test them. A recommendation for another cap video is on safety and bypass capacitor applications. When restoring old tube equipment I always install modern X1/Y2 rated caps on the mains input.

[@w2aew]

Yes - Paul did an excellent video on that. Good point about the X and Y rated caps.

[@sasines]

Alan, another excellent video that I learned much from! Thank you for taking the time to do these videos. Wish they had been around when I was in school!!

[@Radiowild]

Awesome video! Geez... You even had a "old buzzard" bread slicer! You didn't miss anything!

[@fredb9724]

This was a great video! You should do one for inductors too. Thank you

[@rfengr00]

Nice tutorial. Those class 2 ceramics are also frequency dependent. Recently fixed an HF BPF where the designer thought they'd save space by using X7R caps in the resonators instead of NP0. They couldn't figure out why it was not working.

[@rayburke4386]

Hi Alan Great coverage on capacitors. One thing on the Polystyrene, and film capacitors on how to find the outside foil end. That Paul Carlson shows how to do in his video on capacitor polarity, using his circuit or using a Oscilloscope with clip leads. The band doesn't always show the outside end of the foil, as Paul shows in his video. I think that you referenced his video once before. Otherwise the video of yours is very informative, thank you very much. I love to watch your videos, they are packed full of information. Later Ray Burke

[@w2aew]

Thanks - yes, Paul's video on the subject of film cap polarity is excellent.

[@nbreeden]

Bravo, your 2^8 video. Really enjoy your videos and I always learn something.

[@danblankenship5744]

when restoring old test equipment filled with wet-tantalum capacitors, can you use appropriately sized film capacitors?

[@cschang3282]

after great introduction to various caps, would you consider to introduce hot to check or measure good,bad or dead caps? there are too much measurement on Electrolytic caps, however rare to detail explain howto check film caps and ceramic caps, thanks

[@WaltonPete]

Thanks for another informative and interesting video. Your relaxed style makes for easy listening. I liked your use of a meter probe as an improvised pointer at one point!

[@cthree87]

Excellent overview, best and most complete I've seen.

[@whitefields5595]

Very comprehensive - a 'Reference Video' for me!

[@Roy_Tellason]

Electrolytics: You didn't mention the really wide tolerance of those things, typically -20%/+80%! Also, older US-made parts typically have the positive lead or terminal indicated, asian-made the negative. You also said down to 1uF, but I have salvaged some parts (out of a VCR?) that gave me a bunch of 0.1uF, 0.22uF, 0.33uF, and 0.47uF, all at 50V. I'm not sure why you would want to use an electrolytic in this range of values, though. Tantalum: In a place I was working at some years ago, another tech installed a tantalum cap the wrong way around. The result when he powered it up was rather explosive! Mica: It's apparently the practice of some who work on older (antique?) gear to try and turn one around to be able to see the dots and read off the value. This is a *bad* idea, as you'll then end up with moisture getting into the part and it failing. Also, there are apparently several different coding systems in use, at least 2 or 3, the early Radio Amateur's Handbook showed a couple of them IIRC. Also, there's some parts found in old gear with the brand name "Micamold" showing on the case. These are for the most part NOT mica capacitors, but actually paper! And should all be replaced with newer film caps. One manufacturer of electronic musical synthesizers had an instrument where there were two boards having rows of 22uF/25V tantalum caps and some associated parts. Tied into this was a slidepot that would let you choose the release time of the note(s) you were playing. Unfortunately with the way the whole circuit was configured when you put that slider all the way to one extreme, those caps could end up with 30V across them. I was always rather surprised to find very few failures in those instruments...

[@mikeh2520]

I find that much new production capacitors now have tinned copper plated steel leads instead of tinned copper leads. Just take a magnet to some of the parts that you have purchased recently including resistors. What are your thoughts of the effects of steel in the signal path? In my personal experience, I found a big audible difference in sound quality when exchanging a coaxial cable sending the composite audio between a broadcast stereo generator and a commercial broadcast transmitter exciter. The original cable turned out to be copper plated steel and the replacement was a solid copper center conductor cable.

[@w2aew]

I haven't really examined it, but certainly the steel will have higher resistance, which may affect signals in a low impedance environment like audio.

[@MichaelLloyd]

I'm extremely happy to see that you are getting around better. Ditto all of the other positive comments.

[@harbselectronicslab3551]

Great.....sorely needed Video for beginners.....thumbs up for sure

[@DucatiMTS1200]

Perfect summary, excellent by any standard. Thank you for your most valuable time👍.

[@gregcook9915]

This is excellent--the best discussion of capacitor types I've seen. Thanks a lot for doing this.

[@rul1175]

Awesome videos. Can you make a playlist with the Back to Basic Series?

[@nwfalls]

A comment to upvote the video. Great work, thank you!

[@TheDefpom]

Thanks, good video, I was confused about the paper caps with the bands when I came across them for the first time when doing a repair on my hp microwave frequency counter (video on my channel) the band threw me a bit!

[@Wyowanderer]

Excellent video, and very informative. Your use of graph paper reminds me of Forrest Mimms' notebooks.

[@w2aew]

The Mimm's Notebooks were my inspiration to become an engineer in the late 70s, early 80s.

[@ajbrn70]

Great video!! How about doing resistor video also. Thanks

[@jasonlaverty76]

I just checked my parts box and you are correct Sir, nothing higher than 10nF and was looking for at least 0.1uF for DC offset decoupling of audio. Oh well I will have to scout out some film caps.

[@Mythricia1988]

So, if I understand this right, the reason you often want a mixture of larger electrolytic caps as well as smaller ceramics, for filtering power supply inputs/outputs, is because the large electrolytics are good at "picking up" the larger ripple voltages, with lots of capacitance to gulp up larger amplitudes, and the small ceramics pick up the smaller-amplitude or higher frequency ripple... And the smaller caps achieve that simply because they're "faster" (smaller ESR)? I think I'm getting it. Maybe!

[@w2aew]

Yeah, you're getting it. The big bulk caps provide the path for the low frequency currents, and the smaller ceramic (usually) caps take care of the high frequency content. Not so much because of ESR though - it is mainly due to the SRF (self-resonant frequency). See my video on that. The big electrolytic caps have a self resonant frequency well below 1MHz typically, which means that they look inductive above that. The ceramic cap's SRF is much higher, so they still behave as capacitors at high frequency.

[@Mythricia1988]

Gotcha. Will have to check out that video as well. Cheers!

[@misterhat5823]

The smaller capacitors often have a a smaller ESL, not ESR, and this relates to SRF as w2aew mentions.

[@philipdonovan6510]

Totally informative and useful. Thank you for a well done and explained video on the most popular and visible caps!

[@RicardoDiLago]

Love these videos, very well and clear presented. espescially like that you show it with test equipment. many others just talk about theory. well done!

[@waynegram8907]

Back in the 30's to 50's the RF Radio designers would use capacitor temperature coefficients to have this technique called "Evening Effect". I'm not sure if you know about this Evening Effect but if one capacitor drifts up or down the other capacitor will drift in the OPPOSITE which causes them to have this evening effect. Any reasons why this happens or how to design a circuit to have this evening effect?

[@hybridskeeter]

I didn't realise how ignorant I was about capacitors. I just want to thank you for passing on your knowledge. PS. Glad you are feeling better :-)

[@w2aew]

Still hobbling around with a crutch, but getting more mobile everyday. Thanks.

[@InXLsisDeo]

I've noticed you've never made a "how to buy a second hand oscilloscope" video, showing what to look for and how to evaluate before buying; I would be very interested in one, both for analog and digital scopes.

[@w2aew]

I'll add that topic to my list.

[@InXLsisDeo]

Thank you ! :)

[@AnilDas-jd5dk]

R

[@Lyndalewinder]

Very good review of capacitor types

[@waynegram8907]

How do you test how much DC voltage is passing through the Capacitor? If you apply a DC voltage on ONE end of the capacitor lead and other capacitor lead should measure Zero Volts? but what other types of test can you do to measure how much DC voltage is passing through the capacitor?

[@AD-wm9if]

with regards to the dielectric soakage discussion, presumably you're in a space with quite a lot of EMF generated by all the equipment and wiring. How do you know that's not just being induced in the wires to create the voltage in the capacitor just through the energy that'll be in the air?

[@douggale5962]

Is it always true that you can make any capacitor non-polarized by connecting a pair of them together with their negative lead and use the positive leads as the capacitor leads? You'd end up with half the capacitance of one of them, and double the voltage rating, right?

[@bobkozlarekwa2sqq59]

I’m restoring an old Radio Shack scanner. It has about 10 .1 if aluminum electrolytic that need to be replaced. What advantage or disadvantage would there be if I used .1 if disc caps?

[@w2aew]

Gee, 0.1uF is pretty low for electrolytics, but maybe they had reasons for doing that. If they need replacement, probably no harm in trying ceramic, unless the design relies on the parasitic characteristics of the electrolytic (which would be poor design practice).

[@caulktel]

Good video Alan, never too old to learn.

[@user-mj3ef]

Thanks for the video. I need to design an antialiasing filter using a design tool. My worry is if the stage caps vary with temperature then the filter characteristics might change. The caps I need now are from 2.2n upto 47n range. I cannot find C0G or NP0 ceramic so I bought KEMET’s R82 series PET capacitors. Do you think PET caps are fine for such active filter stages? Mica are too expensive.

[@w2aew]

Yes, film capacitors will give you better stability than ceramic caps using X7R, Y5V, Z5U dielectrics.

[@electronicsexplained287]

Amazing video series, I really can't thank you enough. Greetings from Kurdistan my friend

[@philpicc9238]

All this time and I didn't know about the banding on the film caps. Thanks

[@peterjohnson5586]

Incredible. I wish you were my EE prof.

[@KD0CAC]

On the RF side of things , I've never picked up on if door knob caps are polarized ? Thanks again .

[@w2aew]

No, they're typically mica or ceramic, non-polarized.

[@KD0CAC]

Thanks Allen John

[@jonmullins8460]

Another very informative video. One of these years I'll know about .001% of what you do.

[@AB-yu2tj]

thank you very much for sharing. I was wondering when looking at a component data sheets and in there are graphs of the measurement for the component. are all those measurements for the graphs referenced to ground (earth ground). I mean when I am measuring DC or digital signal do I got to put the ground on the earth ground or the negative of the voltage supply to the IC chip being measured?

[@w2aew]

In many (most) cases, the circuit ground and earth ground are the same. Measurement graphs and voltage measurements/specs are typically measured against the circuit ground unless otherwise stated. When using a VOM or DMM, you can place the probes at any two points you like to measure the voltage between. When using a scope, you have to be more careful, since the ground side of the probe is connected to earth ground. Again, in most cases, circuit ground is the same as earth ground, so connecting the scope probe ground there is OK.

[@AB-yu2tj]

@@w2aew thank you thank you very much. my apologies if my questions are simple. but I have 1 or 2 more question. I be glad to watch another video about them if you have made one. I am new to scopes but been using DMM of higher quality for many year in the field repairing equipment. I am trying to get familiar with PCB diagnostics. Just so I understand please, lets say there is a VCC or VDD +5VDC. Do I attach the scope GND to Vss / VEE which ever is specified? how about probing in areas with higher voltages in PWMs. I am aware of isolation transformer and in progress of building one. I been a field technician (or 1/2 a technician since I don't now how to use a scope). with the way equipment manufacturers are designing and pricing replacement boards, I got to either learn how to repair them in a timely manner or quite and become a parts sales person. After banging my head against the wall for a couple years finally I learned how to repair a $2800 PWM, with no help from scopes. but by the time I was able to repair these boards most people were buying newer model machines. the $2800 PWM is the not the expensive board in the group. thank you again for your replay. videos like yours is like water for a thirsty one like me. .

[@w2aew]

@@AB-yu2tj The answer depends on the circuit. In some cases, VEE or VSS will be the same as Ground. In other cases, VEE or VSS might be a negative voltage with respect to ground. When using a scope, the probe ground should be connected to ground in the circuit. You will have to check your circuit to see if VEE=GND or VSS=GND in that case.

[@AB-yu2tj]

@@w2aew thank you thank you.

[@stanholmes4293]

Could you comment on the best capacitor to use in a magnetic loop antenna. I have read the capacitor efficiency is important in the magnetic loop. Designing the antenna for 10m - 40m with a 3 m circumference loop, I notice the capacitance is relatively low on bands 10m to 18m but increase for 20m and 40m as well as the voltage. Which is the better variable capacitor to use split stator, butterfly, flat plate sliding capacitor or a non linear type. How would you measure the efficiency of these capacitors.

[@w2aew]

Hello Stan - I'm not an expert on mag loop antenna design, but I'll give you my thoughts. I would think that efficiency will largely be determined by the effective ESR of the capacitor. So, designing with good quality conductive materials that can handle the high circulating currents is important. Mag loop antenna's tuning capacitor operates at very high voltages, even at moderate power levels, so it is important to select a design that can withstand the high operating voltages. It looks like the new version of the ARRL Antenna Handbook has some updated material on small transmitting loop antennas, maybe it will have some good advice on the capacitor design.

[@superdau]

Are the SMD "box" type electrolytics (I pretty much only saw them in black or orange) always tantalum? Or are there aluminium electrolytics in that form factor as well?

[@mariushmedias]

The mustard/dark orange ones are typically tantalum , the gray/black ones are polymer-tantalum solid capacitors (search for POSCAP , a type of capacitor made by Panasonic) or straight aluminum-polymer electrolytic capacitors (for example search for SP-Cap for a series of capacitors made by Panasonic using this combo)

[@rish1459]

Great job again; I love re-learning this stuff in a very concise manner! Bravo

[@Harrzack]

Great background info. Wonder if you could do a talk on proper, basic power filtering on Arduino-style projects. I don't use "shields" but prefer to build up a board with a Pro Mini and add needed IC's, etc. I recall board Vcc should have electrolytic's & each chip should have a small cap - Vcc to ground. A talk outlining best practices in board construction would be a great help. - Alan R. W2AVR

[@w2aew]

Your recollection of using a bulk electrolytic on the board, and a small ceramic cap at each IC is a very good place to start, and would qualify as a "best practice".

[@johnwest7993]

I'm a bit late to the video, but... Tantalum capacitors ARE electrolytic capacitors. That's why they are polarized. An electrolytic process maintains the dielectric layer of both the aluminum and tantalum, so you can't reverse the polarity or the dielectric insulation deteriorates and the plates short together. The 2 basic types of electrolytic caps are aluminum and tantalum. 'Non-polarized' electrolytics are simply 2 high voltage aluminum electrolytics (thick dielectric,) that are hooked back to back.

[@seans9885]

Dear Professor, Would you Please make a tutorial from A to Z on how to work with the Signal/function generator and oscilloscope for hobbyists and beginners? I need it to calibrate and fine-tune my R2R tape recorders and do small troubleshooting. Deep Regards

[@w2aew]

Everyone's needs and usage of signal generators and oscilloscopes is different - it wouldn't really be practical to do an A-Z video covering everything that hobbyists and beginners would need, without it being hours long. I have several beginner tutorial videos on signal generators and oscilloscope usage, including videos on the most common mistakes people make (search for the work "wrong" in my index file found here: www.qsl.net/w2aew/youtube/W2AEW_video_index.pdf). There are also a lot of videos on the basic operation of oscilloscopes and their fundamental controls (vertical, horizontal, triggering, probes, etc.).

[@keghnfeem4154]

polarized cap's connect with negative sign on the cap to the negative wire?

[@w2aew]

You just have to obey the polarity indicated on the capacitor when using in the circuit. Make sure that the negative lead is at a lower voltage than the positive lead - at all times.

[@davidholman2536]

Superb tutorial Alan. I looked through the full lists of videos but couldn't find one on selecting inter-stage coupling capacitors at RF. Would that make a good back to basics film? Up to 70cm and 23cm please. 73 de M0YDH

[@w2aew]

Anything that is listed for RF applications, such as Mica, Film and the higher stability ceramics (NP0/C0G, X7R) would be suitable.

[@davidholman2536]

@@w2aew yes thanks. It was the choice of value that was my concern. Is it always rearranging the capacitive reactance formula to get farads at frequency and input impedance of the next device?

[@w2aew]

@@davidholman2536 Generally pick the lowest value that will present a reasonable reactance for the lowest frequency, considering the source and load impedance on either side.

[@Taran72]

thank you so much for this video: I took apart an old flat screen tv and wasn't sure how to re-use the capacitors I found on the boards.... :)

[@camiemengineer]

VERY GOOD THANKS .. Didn't know about reverse voltage sensitivity of tantalums !

[@rozendam]

Thank you. Knowledge needs to be shared!

[@totolesslie]

What is the differences between all the capacitors you've presented and "oil based capacitors"? Also, are there any major differences in quality/ESR/temp/triggering/storage/etc characteristics between commercial capacitors (available for everyone) and "military/medical/science/high end customers" capacitors? I know that is a huge differences between "commercial use" and military/medical for transistors....

[@w2aew]

Oil filled capacitors are generally for high power (high voltage, high current) applications where the extra dielectric strength and thermal conductivity are needed. Military and other high-grade capacitors are generally the same from a performance standpoint as the commercial grade parts - the big difference is in material selection, quality control measures, etc. to ensure very high reliability as well as operation in extreme environments (high/low temperatures, etc.).

[@tonythediyer8537]

Nice learning video, thanks so much! The video dredged up some memories of my device classes back in the '80s. I haven't been involved enough in electronics recently to inflame those neurons, but your video helped charge those up (pun intended). But, now, that I am getting back into electronics repair and design, it is a nice refresher. Q: I was wondering how to id those NP0, COG, Y5V and Z5U varieties of ceramics if I went to some of my old caps in a drawer and picked them up to use in a circuit? I now know, thanks to your video, what to choose when purchasing them. Also, it would be nice, for me anyways, if you do a tutorial on identifying the values of some of those smaller caps. As I recall, the values are written in sort of a scientific notation; i.e. 101k, etc. I know, I could crack open those text books that I still have from my old classes, but that is hard work. LOL I am studying those as well, as needed.

[@alanwolke6253]

You can usually tell by the value. Less than 1nF, it's probably NP0. NP0 are often marked. Class 2 are also more microphonic. Connect to a scope input at a sensitive setting (like 1mV/div), and hit the cap with your fingernail, a pencil, etc. and see if you see a deflection on the scope. The numeric code is that the first two digits are the figures in the value, and the third is the multiplier - how many zeros to add. Result is the value in pF. 101 is 100pF. 472 is 4700pF, or 4.7nF.

[@Mrlamister]

Is there a similar video for resistor types?

[@w2aew]

Not yet, but I can add it to my list...

[@Mrlamister]

Great! We just had a discussion about resistors and capacitors in our research group and I forwarded them this video. Immensely helpful for us non-electric engineers!

[@PapasDino]

And inductors too! Toroid mix types and applications would be interesting as a subset. 73 - Dino KL0S