How to Make a Vacuum Diode

One Methods:Operating Instructions

Some electronic experimenters wish to understand how what they are working with works, and occasionally will want to make something of their own. This will cost nearly nothing and will work quite well.


  1. 1
    File the top of a 200 watt light bulb open to create a 1/4 " hole, letting the vacuum out of the bulb.
  2. 2
    File the side open to forum a 14 inch (0.6 cm) hole .
  3. 3
    Stick a clothes hanger in the inside of the bulb with a loop with a slight curl on the end and lay this around the filament, but make sure it doesn't touch it.
  4. 4
    Seal the top end shut by getting the top of the bulb red hot and touching a piece of broken glass against it and let it melt. Make sure the seal is tight though! Tight seals are vitally important for this project!
  5. 5
    Stick the second piece of wire into the other hole, making sure the second wire gets close to the place where the first wire almost touches the filament. This must not touch the filament!get it as close to the filament as possible.
  6. 6
    Seal this connection shut as you did the last.
  7. 7
    File a third 14 inch (0.6 cm) hole in the other side of the bulb. Seal a tube of glass to the area around the hole that you made. make this about 2-1/2 inches long.
  8. 8
    Attach the pump to the end of the tube and pump out as much air as you can.
  9. 9
    Get the tube red hot and pinch it together with a pair of pliers.

Operating Instructions

  1. 1
    Power the bulb from the bottom as normal, feed the current to be rectified through the top two leads. This should be at least 120 (house) volts.


  • Do not short out the filament!
  • Make sure all the connections are sealed well.


  • Be careful when working with mains voltage.
  • Don't burn yourself with the torch! Burns = ouch!

Things You'll Need

  • Torch
  • 200 watt light bulb
  • Glass tube
  • Cut sections of clothes hanger
  • Pliers

Article Info

Categories: Science