Perhaps the simplest way to make a powerful high voltage DC power supply is to adapt an old PC/computer monitor. This will give you around 24kV and somewhere in the high triple digit microamps when flying a lifter.
As shown below, you just:
Converting the PC monitor into a high voltage power supply
The high voltage wire being used is the one that normally goes to the CRT display. To save power, some PC monitors will power the display only if there is a computer connected. They are usually labeled in some way as energy saving types of monitors. That kind of monitor will not work as a high voltage power supply, unless you're willing to connect to a computer when working with high voltage, which is not a good idea since you might accidentally zap the computer, and you also won't see what the computer is trying to display since you'll be using the wire that normally goes to the display as your high voltage output wire.
You can test this by disconnecting from any computer and turning the monitor on. As long as you see something on the display, even a message like that shown below, then you can use that monitor.
The next step is to open the case and can be dangerous. If the monitor has been on in the past 24 hours then there may still be a high voltage inside the monitor. So leave it off for at least 24 hours before opening it. Even then, be careful when you open it up to not go anywhere near the cathode ray tube shown below.
The ground wires
For the ground wires look to where the power cord entered the monitor. In the power cord there are three wires with different colored insulation on them: black, white and green. Inside the monitor, the end of the green wire will be screwed to the a metal plate somewhere. There are likely wires going from there to other metal plates, grounding them.
NOTE: A good point has been made that instead of connecting to the green ground wire, the white NEUTRAL wire might be a better choice technically. This is because in many houses the ground wire goes to a type of breaker that will trip if it detects some amount of small milliamps of current. That's because ground wires don't normally have current through them unless there's a fault. Depending on the country you're in these are called GFCI breakers or RCD breakers and possibly other names. While technically that's true, in this case it works okay with ground because the current is typically in the microamps.
I used existing holes in one of those plates to bolt on two wires.
Make sure you make a good electrical connection between the wires
and the plate. I even used sandpaper to clean the plate and include
a star washer to help penetrate any layers. This is done by making
the attachment in the order:
For this monitor, as shown below, I sent one ground wire out a hole in one side and I drilled a hole in the top-front of the monitor and ran the other ground wire out through that.
One of the ground wires is for discharging things to make things safe after turning off the power supply. I taped that to a stick which I refer to as a discharge stick. I even arranged it so the discharge stick could be attached to the side of the monitor when not in use.
NOTE: The wires I used for the ground wire have insulation that's actually too thin. It would be better using high voltage wire with thickness like that of the high voltage wire discussed below.
The high voltage wire
The high voltage wire is the one shown below that enters the CRT through the rubber cup. As stated above, it's best to wait at least 24 hours after turning off the monitor before going near this part, for the charge to dissipate. Even then, plug in the monitor, BUT LEAVE IT TURNED OFF, and lift up the edge of the cup with insulated pliers and touch the connector underneath with the end of the ground wire on the discharge stick to discharge any remaining charge. At this point it's safe to touch.
NOTE: It's even been suggested that the insulation on the pliers may not be sufficient and that you should pry up the rubber cup using another long plastic stick instead.
Use the pliers to unclip the wire from the CRT and cut the wire as long as you can. Strip the end of the wire carefully since there are two layers of thick insulation and it's easy to cut through the thinner wire insde. Make a hole in the case and push the end of the wire through.
As shown below, I got fancy and extended the wire and attached a ring connector to it. I also made a plastic support at the top-front of the monitor where I connected the high voltage wire to a round metal ball using a bolt. This acts as a mounting point for connectors with wires going elsewhere (as you can see in the lifter test setup below.) I simply unbolt it and attach more connectors. The roundness is important to minimize leakage through ionization. The ball was something I bought at a lighting store and I don't know what its original purpose was. Drawer knobs also work.
Testing the PC monitor high voltage power supply with a lifter
To test it I connected it to a lifter, as shown below. It's VERY, VERY IMPORTANT for these PC monitor high voltage power supplies that you connect around 240 kilohms of at least 2 watt rated resistance in series with the output circuit. I do this as shown below, on the ground side, avoiding issues with sharp edges that way. If you don't include this resistance then you'll likely damage the power supply when you have a few powerful sparks. The added resistance decreases the current from the sparks.
I also measured the voltage using my FLUKE 80K-40 high voltage probe as around 24 kilovolts while the lifter was flying.
Video - How to Make PC/Computer Monitor into High Voltage Power Supply
The video below goes step-by-step through how to turn a monitor into a high voltage power supply. It also demonstrates using it to fly a lifter and while measuring the voltage being used for that using a FLUKE 80K-40 high voltage probe.