Homemade Capacitors ~50kV

[Krumlink]

It occured to me that buying some 50kV capacitors was going to kill me. I need 12 of them, which cost 10$ each, so 120 dollars. That was not happening. I then remembered how a capacitor is made. Alternating layers of a conductive material (aluminum, steel, etc) and a insulator (plastic, mylar, etc). I then decided it was time to make some!

Things you will need:
3/4 Inch wide WOOD dowel
Aluminum Foil
Saran Wrap (plastic wrap)
Electricians tape
20-24 gauge wire
Total cost: around 5$

That sounds pretty Good! Sure beats 120$! Ok lets get started.

Tools:
Hacksaw
Your hands
Gloves (safety first)
Safetly Goggles (safety first)

The target of the capacitance of these capacitors is 500pf, or 0.5nf. I am simply using some household materials WITH NO CHEMICALS.

The technique I am using is one I came up with. It is called the "wrap plate"
technique. Ive never done this before, and made this up on my own.

Step 1: Roll out a large peice of aluminum foil, and a very large peice of plastic wrap out also.

Step 2: Measure out the aluminum foil into 4x6 inch peices. Do this for the whole thing. This capacitor requires only 2 plates. Then take 2 wires and tape them to each plate, making sure they are securely on.

Step 3: Cut a large peice of wrap that can cover the capacitor plate with alot of extra. make sure it is completely wrapped with no exposed sides.

Step 4: Repeat Step 3 one more time for another plate.

Step 5. Push the wire leads out to the side so that they wont be wound up when it is rolled up. Then Wrap the plates together so that they are wrapped toghether, with wires sticking out on opposing sides

Step 6. Cut your dowel into 4 inch peices.

Step 7: Roll the capacitor plates (NOW TOGETHER) up in the dowel VERY TIGHTLY. Make sure the dowel is slightly smaller or same size as the capacitor plates to make it look neat.

Step 8: Then wrap the entire capacitor up in saran wrap very tightly with no air in it.

Step 9: Measure the capacitance. Make sure it isnt shorted out, if it works, you should see...

2.5 nano farads? Thats insane! You cant beat that for somthing that took 5 minuts to make! That is a incredable capacitor! All the other homemade ones I have seen are so elaborate, with chemicals and stuff. But with just saran wrap and aluminum foil and a wood dowel, thats great! Thats amazing! Hope it works out for you like it did for me!

 

[ronsimpson]

When I was young and more foolish I needed a capacitor for a laser power supply.
I used a double sided printed circuit board. Copper on both sides made the capacitor. Warning; remove the copper from the outside ½ inch if the board. If the copper goes to the edge of the board the power will jump from one side to the other. Hope you can find some raw PCB stock.

 

[Krumlink]

This is way cheaper and was much easier. Anybody can make these!

The wood dowel prevents arcing from one side to the other. Also, if you wrap the Plates just right, the aluminum wont go to the outer edge.

 

[ronsimpson]

Did I read correctly?
You have 50KV across two layer of plastic wrap?
In production, I had to vacuum out all the air to keep sparks form happening. I used to make millions of 45kv transformers. We had to work to keep air out if we wanted to make it past the warranty. I have many rolls of transformer tape and I could have used plastic wrap.

 

[Nigel Goodwin]

Sounds rather foolhardy and crap! - certainly it's not going to like 50,000V across it!.

I suggest you try googling for 'leyden jar' which is a more likely prospect.

However, I strongly suggest you don't even think of playing with such high voltages - we wouldn't like to lose you! (but don't put it to a vote! )

 

[Krumlink]

Lol

I Guestimated 50kV. I have seen look-a-likes put into marx generators, and I am making a better version. Besides, I can replace these easily.

 

[ronsimpson]

Krumlink listen to Nigel and live longer! He has more experience than the next 100 people. Where are you getting the 50kv from? If there is any current behind it you will not make 110 postings.

Assuming you capacitor lasts past the first 1uS then it will degrade with time. Probably your cap will last and you will post “success!” That plastic will break down in time. We make things like this in a small vacuum to keep contaminates out. One finger print and it will not last. With or with out the finger print the plastic will breakdown and light-off the cap.
Keep safe!!

 

[Krumlink]

Lol I am listening!

A problem I have found with them is that they are inconsistent. It is hard to make them close together. I will keep them, but I am going to make Massive ones. I was talking about the rating of the Caps as 50kV, not as a 50kV input. They would only see about, around 15kV. I have done the reading and I am not walking into a wall. Nigel is as hard to please as a girl sometimes so he can be picky

I am also going to have a mechanical Trigger, aka A slow spinning motor with a Wood Circle with a Wire connecting between each side. I am going to Make a marx generator, so tips are appreciated.

I also am having trouble hooking up my flyback transformer from a old monitor. I was going to call my TV repair guy again and ask about it.

 

[Nigel Goodwin]

I was talking about the rating of the Caps as 50kV, not as a 50kV input. They would only see about, around 15kV.

I seriously doubt that the insulation will reach anywhere near that - I wouldn't expect it to survive more than a few hundred volts?.

 

[Krumlink]

My new capacitor model is very beefy, close resembelence to this, which can withstand 33kV!

You are as hard to please as a girl, so stop it
**broken link removed**
Go to party cup capacitor

 

[sam2]

Lol I am listening!



I also am having trouble hooking up my flyback transformer from a old monitor. I was going to call my TV repair guy again and ask about it.

Look here: **broken link removed**

http://uzzors2k.googlepages.com/flybacktransformer

**broken link removed**

 

[Krumlink]

Thanks alot!

 

[Sceadwian]

I've already looked this up, in order to approach those kinds of voltages with saran wrap it'd need to be a milimeter thick. I check because the industrial wrap we use at work is the same material just thicker and I had the same idea. I looked up the breakdown voltage of the material. That cap will work, but only to a few hundred volts or so, a quick test will not prove your cap works as it can take time to properly test a cap. This is why high voltage capacitors are expensive. Check out this site for what many high voltage phenoms use for home brew high voltage caps.

http://www.geocities.com/CapeCanaveral/Lab/5322/bottle.htm

 

[Krumlink]

Ive made some Large Capacitors out of Thick plastic cups, that have a capacitance of 500pf. They are all very close to eachother, so they are useable. I highly suggest this method, because it is very consistent and works well.

When I run 120AC through a bridge rectifier, what is teh voltage output? isnt it around 400VDC?

 

[Krumlink]

Homemade Capacitors not holding charge

For some reason my 500pf homemade capacitors are not holding their charge once charged. What is the reason behind this? They are made out of plastic party cups with aluminum wraped around the out side. They are then put into another party cup that is also aluminum wraped but the lead facing the other way. They are then put into another party cup to insulate the outside. What is the problem?

 

[audioguru]

500pF is such a low value of capacitance that the voltage is drained away very quickly by anything like a voltmeter or even humid air.

 

[Krumlink]

ok, but will these work for a marx generator? How can I ensure these will work?

 

[kchriste]

You might have better luck with glass jars.

 

[Krumlink]

I dont have any glass jars laying around, so how do I test these?

 

[audioguru]

Mickey Mouse capacitors are not high voltage ones.