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!

Category:

Science & Technology

Tags:

• Capacitors
• mica
• mica_capacitor
• ceramic_capacitor
• kapton
• copper_foil
• home_made_capacitor
• uf
• mfd
• pf
• nf
• silver_foil
• Radio
• vintage_radio
• crystal_set
• crystalset
• gw0jxm
• g0jxm
• 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]

@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]

@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

[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

[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.