The Rectifier Circuit

We want to have the inner grid negative and the outer grid grounded. To do this we need only the negative output of the NST. The act of converting AC power to DC is called rectification. Since we want to have one polarity we will need to rectify the output of the NST. There many ways to do this but this is the most simplest, all we need is two diodes. These diodes can be bought online or ripped out of an old microwave. Arrange the diodes as follows:

 
Here is the circuit in real life:

The rectifier circuit is done!

Next: Feedthroughs

The Pump

For a fusor to work you need a vacuum. Having too much air in the chamber where the reaction will happen will slow the ions down and cause no reaction. This is why a vacuum pump is needed. The pump will suck out most of the air in the chamber allowing the little remaining air to ionize and move freely. The pump you will need must be a vacuum pump. Rotary vane vacuum pumps are the best to go for, this is the one I went for -

 http://www.ebay.co.uk/itm/Industrial-Quality-Professional-Vacuum-Pump-50-l-min-/141067535164?pt=UK_BOI_Medical_Lab_Equipment_Lab_Equipment_ET&hash=item20d847c33c

Im sure there are many other vacuum pumps out there that would also work but generally 1/4 Hp, 3 CMF, single stage rotery vane vacuum pumps are the best to go for.

Next: The Rectifier Circuit

The Control Circuitry

Really all you need for a fusor is an On/Off switch, that can just be your wall socket plug. To spice up my fusor and to give me more control over it I have included many more controls as you can see in the picture above.

Variac - The knob on the left is a variac, if you are planning to by any type of controls for your fusor this is the most important one to get! Without it the fusor will only operate at its default voltage. If your grids are too close together then the power will just arc between the grids instead of creating a fusor effect. It is almost essential for you to have a variac. I must also stress that a light bulb dimmer switch or potentiometer will not work either, it must be an auto transformer!

Big Red Switch - This controls the main power. When the red switch cover is up the user can flip the switch to turn the fusor on, pushing the cover down will also turn off the switch below it. This acts as a safety precaution so nothing can knock the switch on and it can also be quickly turned off. If you just had a variac you would need to turn it all the way down which takes time

Red Switch - This turns the pump on.

Green Switch - This turns on the voltage screen.

Voltage Screen - This easily indicates to me the exact voltage going into the NST (Not the fusor as the screens can not handle 6KV !) The variac panel only gives me a percentage of the total power.

Second Green Switch - This turns on the amperage screen.

Amperage Screen - This easily indicates to me the exact amperage going into the NST (Not the fusor as the screens can not handle 6KV !) The variac panel only gives me a percentage of the total power.

Here all of the controls are activated. Note that the two red switches light up but I just not hooked them up to any power yet. Also, when the fusor is done I will add lables to all of the controls.

Next: The Pump

The Grids

You will need an inner grid and an outer grid and they must be spherical. I am using a large spherical spring connected to a large bolt for my inner grid and a coil of metal wire for my outer grid. Although my outer grid is not very spherical it should still work. Note: Do not try and solder a grid as they get extremely hot and will melt. Both grids must be conductive. Finally, connect a wire to both grids and feed them out of the vacuum chamber making sure not to break the airtight seal.

Next: Control Circuitry

The Frame

Its time to build the frame. For my fusor I will have a box. Inside will be all the circuitry, the front panel will have the controls on it and there will be no back panel so i can easily access everything if i need to. On the top of this box will be the vacuum chamber and the pump. I will have a wooden panel on top of the chamber and wingnuts connected to pillers coming up from the box. Tightening the wingnuts will push down on the vacuum chamber pushing it into a rubber sheet. This will allow me to create a better air seal but will also allow me to open up the chamber and service it if necessary. Once you have drilled it all together its time to move on!

Next: The Grids

Collecting Parts

First of all we need to collect the materials we need to make it. I'm making a eoper wooden frame for my fusor, you can see the wood in the picture above. You will als need:

• A vacuum pump
• A airtight transparent container
• A high voltage power source
• 2 HV diodes
• Something to make the grids out of(I used metal wire and a large spring)
• Control circuitry (Thing like variacs and switches to control the fusor.)
• A grounding rod to ground the NST and outer grid.

Everything here apart from the HV power source and the pump is relatively cheap and easy to get.

Once you have got everything its time to start building!

Next: The Frame