1. Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
    Dismiss Notice

Homemade Capacitors ~50kV

Discussion in 'Members Lounge' started by Krumlink, Aug 30, 2007.

  1. Krumlink

    Krumlink New Member

    Joined:
    Aug 10, 2007
    Messages:
    2,080
    Likes:
    20
    Location:
    Michigan, USA
    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!
     
  2. ronsimpson

    ronsimpson Well-Known Member Most Helpful Member

    Joined:
    Apr 17, 2007
    Messages:
    7,254
    Likes:
    961
    Location:
    Loveland, CO USA
    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.
     
  3. Krumlink

    Krumlink New Member

    Joined:
    Aug 10, 2007
    Messages:
    2,080
    Likes:
    20
    Location:
    Michigan, USA
    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.
     
  4. dave

    Dave New Member

    Joined:
    Jan 12, 1997
    Messages:
    -
    Likes:
    0


     
  5. ronsimpson

    ronsimpson Well-Known Member Most Helpful Member

    Joined:
    Apr 17, 2007
    Messages:
    7,254
    Likes:
    961
    Location:
    Loveland, CO USA

    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.
     
  6. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

    Joined:
    Nov 17, 2003
    Messages:
    39,228
    Likes:
    641
    Location:
    Derbyshire, UK
    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! :D )
     
  7. Krumlink

    Krumlink New Member

    Joined:
    Aug 10, 2007
    Messages:
    2,080
    Likes:
    20
    Location:
    Michigan, USA
    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.
     
  8. ronsimpson

    ronsimpson Well-Known Member Most Helpful Member

    Joined:
    Apr 17, 2007
    Messages:
    7,254
    Likes:
    961
    Location:
    Loveland, CO USA
    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!!
     
  9. Krumlink

    Krumlink New Member

    Joined:
    Aug 10, 2007
    Messages:
    2,080
    Likes:
    20
    Location:
    Michigan, USA
    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 :D

    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.
     
    Last edited: Aug 30, 2007
  10. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

    Joined:
    Nov 17, 2003
    Messages:
    39,228
    Likes:
    641
    Location:
    Derbyshire, UK
    I seriously doubt that the insulation will reach anywhere near that - I wouldn't expect it to survive more than a few hundred volts?.
     
  11. Krumlink

    Krumlink New Member

    Joined:
    Aug 10, 2007
    Messages:
    2,080
    Likes:
    20
    Location:
    Michigan, USA
    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 :D
    http://www.altair.org/tesla.html
    Go to party cup capacitor
     
  12. sam2

    sam2 New Member

    Joined:
    Sep 19, 2006
    Messages:
    144
    Likes:
    0
    Location:
    California S.F. bay
    Last edited: Aug 30, 2007
  13. Krumlink

    Krumlink New Member

    Joined:
    Aug 10, 2007
    Messages:
    2,080
    Likes:
    20
    Location:
    Michigan, USA
    Thanks alot!
     
  14. Sceadwian

    Sceadwian Banned

    Joined:
    Oct 27, 2006
    Messages:
    14,047
    Likes:
    141
    Location:
    Rochester, US
    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
     
    Last edited: Aug 30, 2007
  15. Krumlink

    Krumlink New Member

    Joined:
    Aug 10, 2007
    Messages:
    2,080
    Likes:
    20
    Location:
    Michigan, USA
    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?
     
  16. Krumlink

    Krumlink New Member

    Joined:
    Aug 10, 2007
    Messages:
    2,080
    Likes:
    20
    Location:
    Michigan, USA
    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?
     
  17. audioguru

    audioguru Well-Known Member Most Helpful Member

    Joined:
    Mar 16, 2004
    Messages:
    32,445
    Likes:
    937
    Location:
    Canada, of course!
    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.
     
  18. Krumlink

    Krumlink New Member

    Joined:
    Aug 10, 2007
    Messages:
    2,080
    Likes:
    20
    Location:
    Michigan, USA
    ok, but will these work for a marx generator? How can I ensure these will work?
     
  19. kchriste

    kchriste New Member Forum Supporter

    Joined:
    Jul 23, 2006
    Messages:
    3,677
    Likes:
    47
    Location:
    Victoria BC, Canada
    You might have better luck with glass jars.
     
  20. Krumlink

    Krumlink New Member

    Joined:
    Aug 10, 2007
    Messages:
    2,080
    Likes:
    20
    Location:
    Michigan, USA
    I dont have any glass jars laying around, so how do I test these?
     
  21. audioguru

    audioguru Well-Known Member Most Helpful Member

    Joined:
    Mar 16, 2004
    Messages:
    32,445
    Likes:
    937
    Location:
    Canada, of course!
    Mickey Mouse capacitors are not high voltage ones.
     

Share This Page