I’d like to be able to generate significant voltages of DC for experimentation purposes, but so far am having difficulty in creating/sustaining such high voltages. My hope is that the answer may lie in building a voltage multiplier, but I know very little about such technology. It seems I could potentially build one if I knew what components to get and how to configure them. Any help would be appreciated.
Can a voltage multiplier (such as a cascade multiplier) be built with easily obtained electronics components?
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#1 by billrussell42 on December 18th, 2010
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yes, you can use ordinary diodes and caps for this.
The difficulty is in adequate separation and insulation between stages.
For example, if you start with 120 volts ac, from a simple isolation transformer, you can get 160 volts per stage. You need 400 volt diodes, although I’d get 800 volt ones for extra margin, such as 1N4008, as the price difference is small. For the caps, it depends on the current. I’d get perhaps 20µF caps. You need only 200 volts, but I’d try for 400 volts for extra margin, in case one stage dies.
reference has more details.
edit: I’d be sure to use lots of fuses, like 1 amp ones.
And I’d get some high voltage resistors, so you could build a voltage divider to measure voltages.
For example, a 100:1 divider could be a 99 M ohm and 1 M ohm. The 99 M could be 4 – 22 M and 1 – 11M. You may have to adjust the 1 M upwards to compensate for your voltmeter resistance.
A thousand to 1 would be a 1 Gohm resistor and a 1 M resistor. You can get the Gohm from places like Victoreen, or build it up from smaller resistors.
Note that 1/4 watt resistors usually have a max voltage rating of 450 volts.
I have seen web pages that go into detail on how to do this, re epoxy and other techniques to maintain the high voltage.
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#2 by Dave D on December 18th, 2010
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The easiest way to do this is to strip the flyback transformer and multiplier stack from an old TV set. These usually run at 30kV or so, and have small enough capacitors to be non lethal. Get a service manual for the TV so you can duplicate the drive circuitry required. It is pretty easy to run it at a lower voltage if you want.
It is difficult and long delivery to buy the components separately, stripping an old TV is definitely the way to go.
If you try to design your own stack, you will have two problems:
1) Flashovers caused by inadequate insulation (it is tough to design high voltage insulation).
2) Lethal shock caused by unsuitable capacitors. For example, 20uF at 400V is 100% guaranteed lethal. Your first mistake will be your last. That is known as a “blood and thunder” power supply. The safe way to do it is to use a high frequency and low value capacitors, as in a TV set. While a shock from a TV set can be lethal, that is because of the capacitance of the CRT. Without a CRT, and hence with less stored energy, the power supply is a lot safer. But still take care!
You could also buy one on ebay:-
http://cgi.ebay.com/Laser-Drive-Melles-Griot-High-Voltage-Power-Supply_W0QQitemZ170421562310QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item27adeaabc6