About Capacitors ... Part 1 Making a 3,400pF capacitor. By Andy Davies

About Capacitors ... Part 1 Making a 3,400pF capacitor.
In this first video About Capacitors I show you an 87 year old crystal set that has two mica capacitors in it and then I go on to make a basic plate capacitor, and I give a few tips that I hope will help you.
I'm not an expert in capacitors although when no one would make one off's at a reasonable price or quickly enough, I have made special purpose capacitor to get me through the development phase of radio frequency induction heaters working at 8kV. I have worked with RF ceramic capacitors of up to 20 kV, again in induction heating applications using large (60 KW) water cooled thermionic triodes and I have designed tank circuits to produce over a thousand amps at 100 kHz and yes I have burnt my fingers more than once. Most of my working life has involved work with high power RF components, a lot of it at high voltage and most of it water cooled, when mixing 12 kV 450 kHz and high pressure running water you soon become expert at not letting the water get out!

[@barryg41]

Hi Andy, I was a long time industrial mechanic, now that I am slowing down, ending my work career and looking for a simple hobby, I have found electronics very interesting. I just started a search about the basics of capacitors and found your series. Your time and expertise is greatly appreciated! Thanks

[@Vaylkin]

Please continue to share knowledge instead of selling it to be suppressed. The possibilities are boundless. I applaud this video in its entirety. Always remember to keep it simple. Over complexity make others think they cant do it when in terms of energy everything is simple. I personally believe I am here not for me...but for the rest of you. Perpetuate knowledge. Equal energy for everyone.

[@JUANKERR2000]

Hi, Andy. I used to work with induction heaters ranging from 100 kW to 400 kW. They were used for steel tube manufacturing and ran with 12 kV on the anodes of one or two ceramic bodied water-cooled triodes.

[@AndyDaviesByTheSea]

Hi there, well Tube Welding has to be one of the most fantastic induction heating applications going! I remember when I was quite green behind the ears having a huge row with a tube mill owner. The tube just wasn’t welding and the men were all standing idle, all of the anode and grid readings were correct and I concluded that it was the impeder that was at fault (for those who don’t know, the impeder is a water cooled ferrite device that fits inside the tube that’s formed by the strip local to the induction coil) and of course this meant taking the steel strip out of the mill and stripping some of the rollers out and withdrawing the arm that holds the impeder in the right place. I can still feel the huge sense of relief when we restarted the mill and it welded perfectly. I was right, although it looked OK the impeder had cracked. The mill owner had the good grace to apologise for his disbelief in me. Man I was so glad as I’d never seen or diagnosed that problem before and everyone in the factory thought I was nuts as it took hours to replace something that looked all right. Ah yes, water cooled anodes that were cooled by boiling the water and re-condensing the steam, all working at 12kV DC. Thanks for the comment, it brought back memories. Kind Regards . . . Andy.

[@Dwdanieldotdd]

I started on part 6... going back to check out all of your videos... Tootles... Wade (73's)

[@JSuparman]

thanks for sharing the knowledge, Andy. I am impressed by the 'oldies" LCR-Meter you shown. It is antique and still going strong! I am planning to buy one LCR meter digital type.

[@tvdylan]

this is a great video ! thanks. nice and simple and effective !

[@silver760]

Very interesting,thanks for taking the time and effort to make this video.

[@AndyDaviesByTheSea]

@AllAmericanFiveRadio Hi Rick, thank you. I’m not sure where I’m going with this series but I thought I’d start with a basic capacitor, sometimes I feel burdened with a wealth of experience and I hope that I can hand on a bit. I’m not claiming to have expertise, I do on the other hand, to quote Blackadder, have a degree from the University of Life, a diploma from the school of hard knocks, and three gold stars from the kindergarten of getting the stuffing kicked out of me. 73's Andy

[@AllAmericanFiveRadio]

Hey Andy, Very nice 1924 crystal set. It was very interesting. That would make a great project for Grade/High School Science. Maybe part of a bigger project like building a crystal set. I'm not sure how much the kids get to build stuff now-a-days. Very nice demo. Regards, Rick

[@carmelpule6954]

I visit your site often and I should have congratulated you on your style of teaching and presentations. I have been teaching electronics for a long time , over 50 years and I grew up with the feel for the components I use. As the years go by, I find that my students have no feel for electronic components and no a single student would have an idea what a 20 pico farad capacitor would entail as far as area and separation between the plates are required. It is all hidden from them as these days the equipment does not even get hot so the human relation with the equipment as we knew it is all gone. Recently I went back to play with super-regenerative receivers and I construct my own capacitors using printed circuit copper clad material, simply cutting the required area and soldering a coil to make an LC tuned circuit, My students were curious about all this and asked questions as," how do you know the number of turns required for the frequency concerned?" after I told them my rule of thumb about coils and capacitors to achieve a particular resonant frequency approximation. It is a new world, and people operate things rather than build things. I just wonder if they are being trained to handle the realities of life. Seeing your videos is very encouraging that a gentleman like you finds great satisfaction working alone at home in the spare time you have. Nice peace of mind . Many people these days do not know what they do with themselves when they have some spare time. Congratulations again, not only for the capacitors but for the gentle personality you project.

[@BrentRF]

Thank you very much for the info. I'm already doing some tests with some commercial caps and getting 1.5 vt using two 600uf ganged together in series. I have a bridge rec with the ant and gnd on the AC prongs and the caps on the +/-. But I like building very old school type tube and crystal radios and want a very simplistic old looking cap.

[@AndyDaviesByTheSea]

@dtiydr Hi there, the bridge is a transistor model actually, not quite steam driven but not for off. The kaptan I’m playing with is the last bit I have left over from my working days, I used to manufacture Radio Frequency Induction Heaters, some of the old valve sets used to work with 8 kV on the anode and the output transformer was in the anode circuit was carrying up to 60kW. Although Mylar has the same dielectric strength (give or take) you can’t beat Kapton on temperature ... Andy

[@chbonnici]

Very well presented demo. Thank you

[@buckstarchaser2376]

I found a calculator that gives the properties of a magnetic loop antenna. Although it was fun to play with, it seemed to be telling me that the lower frequency bands weren't going to work well because the capacitor would need to be in the thousands of pF, and variable caps that high don't seem readily available. It would seem that these home-made caps, in parallel, would be the solution. Thanks for the idea!

[@larrypicard5969]

I have build and used a number of mag loops. In practical use I do not recall needing any more than a few hunderd pF. One approach would be to use fixed cap in parallel with a variable cap. Vacuum caps have desirable qualities to use with mag .oops. Ohmic losses are important for mag loops, even tiny ones. You should be using a butterfly cap for a mag loop. Wiper contacts can be lossy.

[@AndyDaviesByTheSea]

@AndyDaviesByTheSea One final point on the Kapton 400 deg C = 752 deg F. One doesn’t normally require that sort of working temperature in a radio but to put it in perspective that’s about twice as hot as the maximum temperature of a domestic oven. When I was using Kapton it had, I believe, the highest dialectic strength of all know materials. Thanks for watching. If you see any unanswered questions and you have the answer please don’t be shy about it, help out. ... Andy

Very interesting

[@gristlevonraben]

Enjoyable video, thank you.

[@KatieRabbitt]

nice video. thank you for posting.

[@soonersciencenerd383]

whats the largest capacitor you've made so far? how far has your radios (crystal) reached,recieved? I built 2 SW, and have gotten radio cuba,nashville, TN, and even European radio!!! one more question- would more windings make a better coil, or larger coil, or thinner wire, or a combination of them (large coil, thin wire, w/ a lot of windings)?? I use what I can find- wire from a wall adapter, coil form from an ink pen inside tube or 2 popcicle sticks). good video!

[@AndyDaviesByTheSea]

Thanks for the feedback. Some days I feel old and antique also but so far I'm still going strong. Kind regards ... Andy

[@engineereuler1762]

Andy. Thank you, sir, for all the genuine resourceful and (many times) genius efforts you put in your videos all those years. They are one of my main television channels now. Watching this specific video from across the pond, reminded me of how great "Great"-Britain is and the inventiveness of her great people. I recently read about how big was the 1850 science fair in comparison to, say, our pathetic Dayton "hamvetion"s, that's what comes to mind here. I wish you the greatest health and to meet you in person one day in Dayton, or at least on the air. 73 great one.

[@Alex1M6]

Hi Andy I really enjoyed the video, I like that particular method of using wood to clamp homemade capacitor plates together. At what voltage does that insulating material you used break down at?

[@AndyDaviesByTheSea]

Hi there, that sounds like quite some project you’ve embarked upon. It sounds like you should be making a video for KZbin about it. I’m glad my video was of some help. Kind Regards ... Andy.

[@BrentRF]

Great video! I'm still learning about caps. I want to make a voltage storage cap to charge from a long wire antennae and then run a small one trans amp for it powered by the cap. Question, for storage of low voltage which is better, fewer thicker plates or many thinner plates?

[@Dazzwidd]

I like the method and choice of materials you used to make this demonstration capacitor Andy. I know about these things already, but enjoyed watching the demo, well presented. What do you suppose the voltage rating of this capacitor might be? I was guessing about 500v but it's hard to tell.

[@AndyDaviesByTheSea]

@AndyDaviesByTheSea You’d be surprised at the amount of wood used in industrial capacitors, there may not be quite so much used now but certainly special purpose equipment (with low production rates or One-off’s) often had handmade capacitors and wood was a natural choice. It wouldn’t be in a position where it would be in the dielectric field or were it was relied upon fro insulation, very often the capacitors would be in an oil filled aluminium case. You could open them up and repair them.

[@AndyDaviesByTheSea]

Hi Barry thanks for the comments. The field of electronics is really very wide, you can get involved with whether you want, construct, collect or simply listen. I have many interests from kiln formed glass, DIY, copper smithing, and on and on but I always seem to come back to radio and electronics and that includes ham radio and making aerials etc. Anyway have a look at allamericanfiveradio on KZbin, that’s Rick’s channel he has loads of good stuff for you. Kind Regards ... Andy.

[@AndyDaviesByTheSea]

OK Good luck ... Andy

[@AndyDaviesByTheSea]

@silver760 Hi there, thank you for the thought, it’s always nice to get positive feedback as without feedback I’m never sure if I’m doing the right thing. Kind Regards ... Andy

[@TheCerberusInferno]

If i use your 3400pf capacitor for induction heating what can be the frequency ?

[@AndyDaviesByTheSea]

2 of 2 Cling film will be harder to work with but for any number of metal plates separated with thin film you’ll get more storage than if you use a thick film. For what you’re playing with the thickness of the metal plates doesn’t matter at all. You would only need thick metal plates if they had to carry a lot of current. Work safely and don’t do anything dumb and start playing with the mains or getting near any overhead power cable with that long wire. Have fun. Kind Regards ... Andy

[@Flippy2k6]

That was cool you rock!

[@AndyDaviesByTheSea]

1 of 2 Hi there A capacitors ‘capacity’ to hold an electrical charge will increase proportionally with the increase in the number of plates but it will decrease proportionally as the air gap between the plates gets larger. So a lot of thin plates with a small gap between each will hold more charge. Capacitors can be difficult to get to grips with but if you want to make low voltage capacitors at home you could use aluminium foil and cling film (glad rap) See 2 of 2

[@HellTriX]

Thank you for this

[@AndyDaviesByTheSea]

@Alex1M6 Hi there, the insulation that I’m using is Kapton from Du Pont it’s 0.1mm thick and it has a stated dielectric strength 290 kV/mm so notionally 29kV for the thickness I’m playing with although I’ve never pushed it that hard (not intentionally anyway) it has remarkable temperature withstand up to 400 deg C and wonderful corona resistance. The only problems are the inability to buy small quantities and the phenomenal cost, worth every penny it if you need it though. ... Andy

[@AndyDaviesByTheSea]

Hi, thank you for the positive feedback. Kind Regards ...Andy GWØJXM

[@AllAmericanFiveRadio]

@AndyDaviesByTheSea Me too on both counts. Quite a bit of material published today is disappointing. If you can read and understand it, you did not need to read it. So I'm not sure what the point is. These learned people have missed the point completely. You must understand the parts that make up a circuit to understand how the circuit works, and before you can troubleshoot it. Dah. Regards Rick

[@AndyDaviesByTheSea]

@Serpico261 Thanks and good luck ... Andy