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

[silver760]

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

[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

[dtiydr]

Interesting video thanks for the upload! I liked the capacitor measurement aparatus, use tubes i assume? Although i go for the digital handheld ones but the older ones definitly have their charm. :)

By the way, i have been looking for thin sheats of kapton tape without glue on it, where have you got the roll you used? Just what i have been looking for, and yes it is truly a remarkable isolation material for HV.

[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

[Serpico261]

that was fascinating. i once tried to make a a cap but this was a complete fail, now i know how to do it

[AndyDaviesByTheSea]

@Serpico261 Thanks and good luck ... 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

[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]

@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

[labobo]

Very interesting

[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]

@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]

@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]

@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