Great to have you back! That capacitor stack looks really cool. Always nice when the math works out.

Fascinating stuff. I very much like how you've thought about the aesthetics of the capacitor and how robust it looks. As stylish and manly as a DYI cap will ever be! It'd be interesting to hear how it all comes together.

I've been wanting to make a magnetic loop antenna for a while now, and this is great! Thanks! - WU2F

This is fantastic. I have a friend in Russia who had one of these capacitors in a picture. I cannot contact him so I am glad you made this video. Thank you.

Nice to see you again.

That's very fascinating! I never thought to use plated PCBs for capacitors before. Thank you for sharing! 73s AF5CG

Absolutely BEAUTIFUL! Such a fantastic display of the marrige of math, geometry, pyshics and electronics. And it all begins to feel more intuitive. It brings my world of acoustic transmission to life.

I am planning to build a mag loop of my own for use on 20m. I have ordered a VVC from Max-Gain Systems. Yet I enjoy looking at problems and have been thinking about the tuning capacitor issue. Thank you for showing the math behind this. I hope you will produce more videos as you develop your mag loop.

Thank you so much. I will copy this in full. Could you please post a brief video of your completed and installed capacitor? I am sure many of us would like to see it in action and so learn even more.

Great to see another video from you! I'm in the middle of designing a magloop for my townhouse attic and was considering making a trombone capacitor but I love the idea of using PC boards instead, and you get higher capacitance to boot! Thanks for sharing!

Hello Derek, Thanks for the cool video. It's very interesting to see how the math matches the product. I like the way you explain it. Now i have confidence to make my own capacitor for my loop antenna. Greetings, 73's PD0ONE.

Thanks for the explanation and lack of a shaky camera.

Wow! This was fascinating! My maths isn't the best but with your help I was able to follow. I was particularly interested because I have a stack of old CDs and was wondering if I could cover them with copper tape, cut them in half and make an air variable capacitor. After seeing this, I may experiment. Thanks for taking the time to make your videos, I for one, appreciate them.

I like it! You do good work. I was contemplating the idea of using PCB material for a longwave antenna capacitor because it was easy to solder to and much easier to cut to shape than aluminum. (Also, I had a good pile of surplus FR4 material available which is the most important part.) But a friend found a need for the material I had, and with the price of copper shooting up I gave him mine to make his project affordable. So it's back to aluminum for me. But thanks to your project I get to see exactly how PCB plate capacitors will work. You even did the math for me. Thank you. BTW, the material on your workbench does indeed couple the 2 plates of the capacitor and increase the capacitance value. That's exactly how electronic stud finders work.

Thanks! I was thinking about this sort of design today--for the same application!--googled to see if anyone did it, and came across your video.

I’ve been meaning to make a large air cap for years and haven’t got to it. It would be for a DDRR antenna. My friend made one and uses a vacuum cap (that I can’t afford) and has amazing results with that little antenna. Glad your getting more into hamming around. Keep on tinkering!

This is a pretty nice and effective way to make a variable cap. I am also facing the same issue as you are, I built a magloop for 20m a while back. It's capacitor was good for qrp txing but not for 25w+ tx. I was thinking of making a variable cap since they can be expensive and not have enough spacing to not arc at those power levels. Good stuff tho.

Excellent video..

Well done 👍👍👍

Top marks, thank you.

Heck yea. I build homebrew mag loops as well

awesome!

Howdy. Freckin' awesome !!! Regards.

Nice tutorial on how to make a high voltage capacitor using blank PCBs, something I've wanted to try for some time. I'm interested in a follow up video to see how well it worked in your loop. It's been said by others that PCB caps tend to drift with temperature so I am curious to see if that was true with yours as well.

Thank you.

Gosh enjoyed I enjoyed vid. I'm.more into crystal radio , low.voltage, but thought you had some good advice atenna

Subbed to your channel for the LVDT episode. Yeah I don't know whats going on with your subs, I haven't seen any of these videos since then in my feed.

VERY GOOD VIDEO

Super

Great explanation thanks. Did you finish it?

Thanks

ESD mat is a high resistance from one point to another. Also it should be connected to ground.

This is just wonderful.Question for you Derek or anyone else here. Can something like this be used for old tube style radios? Indoor loop antenna does not really work that good so with variable capacitor what can be applied to me needs? Anyone please comment. Thanks guys, scotty

Magic that works™

Nice capacitor. One could use an old pc cd/dvd rom tray with stepper circuit to move this unit as well.

what about etching the outer edge away on each single sided board, effectively increasing the air gap without increasing the distance between plates?

Copper corrosion when in contact with the air is a consideration. Just a thought what about double sided copper coated PCBs.?

I like it

Neat build! Makes me wonder about more compact version using mineral oil, like HV transformers do. It won't be such an eyecandy though if you enclose it in non-transparent way (:

if i want to make a higher capacity capacitor, aka more pico farrads, whats the approach ? just add more plates and larger surface area ? very nice construction you have !! well done ! im experimenting with resonance ! and looking to atain a use'able variable capacitor with say 0-1000 pf or more. but i think 1000 pf is a good start.

@The Current Source was your second linear actuator just a video slider?

Redo the measurements isolated from ground?

Hello AmRad, I was curious how things went with air variable capacitor for the MLA. I live in an HOA here in Minnesota. I decided to build one for the 11 meter band, although I am currently studying for my amateur radio license. Have you finished your MLA? Thanks for sharing.

I see a telescope in the background! Do you have any plans to do more astronomy videos?

Can you be more specific on the spacers you use? Is it aluminum tube stock? Did you cut these plates? Did you have issues with the shape of the plates when you tested? You got my wheels turning on using PCB board as long as it isn’t too thin of copper.

How Can One Would Test Such A Capacitor? Vna? Single Multimeter?

yeah but you also introduced inductors with the capacitor

Series LC

Did you ever get this hooked up with your magloop?

If arcing is a problem, why not use a dielectric in between the plates. Polyethylene has a much higher dielectric strength than air, comes in convenient sheets a very low loss tangent and has a relative permittivity of about 2 - wins all the way around. Am I missing something?

hows that mag loop coming?

I tried the same design last night, but the antenna doesn't resonate at all. I don't have full devices for analyzing so I need to drop this project

Hi Derek, I saw a video about using aluminum heat sinks as a variable capacitor by meshing the fins. If you use heat sinks with wide spaced fins, could probably make it a HV variable capacitor. Here's a link to the video. kzfaq.info/get/bejne/iahjmNp4vcvPqKM.html 73 WJ3U

Very cool method and design 😉 KC3ONO

For butterfly cap build a quick video kzfaq.info/get/bejne/fsyEq8md2pqdeI0.html

heat/rf =problem. dont touch it its gonna be real hot,

I think your theory that there are 2 capacitors in series is wrong. Adding a dielectric between air spaced capacitors will always result in a higher capacitance, not a lower one.

A billionth is 10^ -12

so where is the real test with real electricity?

Noob! I made a high voltage super capacitor using human beings... top that!

DUDE WHAT HAPPENED TO YOUR HAND DURING EQUATIONS TIME WTF?

Great presentation. Many thanks. De G3YPZ

For crap sake, you are inventing the wheel all over again, high voltage variable capacitors are on eBay some of them are vacuum capacitors for 20kV 25pF to 1500pF, what is wrong with you?