HV DC power supply options? (30kV/20uA)
Taylor Wass wrote 08/16/2015 at 07:04 • 1 pointHi guys, we are designing a capillary electrophoresis power supply and were wondering if somebody had some low cost ideas for providing the following source:
Adjustable constant voltage (5-30kV DC) - happy to have it operate in steps (i.e 5, 7.5,10,12.5,15,20,25,30)
This will give us a minimum working system, but ideally we want a centre-tapped dual supply, with 2 outputs:
1 x +5-30kV
1 x -5-30kV
Current is usually 10-20uA (ideally want a system that cannot go much higher for safety)
Ideally I want to run this system off 12VDC to allow solar power/(relative) SAFETY, which is proving difficult to design cheaply!
At the moment, we have found the following options:
This can output at 200uA up to 10kV DC from a 1-15V DC supply, so can we step it up to the 10-30kV range (as we only will draw ~20uA)?
Solution for prototyping at this stage is a neon sign transformer, connected to voltage multipliers. Not ideal in the production unit as it runs off of 240V
Other ready-made alternative is this 240V guy off aliexpress (SCARY and not ideal as lacking -VE supply - is it possible to 'convert' a positive voltage into a negative one?):
Good luck everybody :)
Taylor
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You pretty much have to roll your own as you have really specific requirements or pay something to make these for you as note your "production" requirement. From the way the question is ask and your looking at premade modules, I would assume that you do not have the experience to do the design yourself. There will be some nasty safety agency compliance test if you ever decided to sell this. :P tl;dr onesy is easy, but making a product will cost you big time.
The closest thing you are looking for is actually "CCFL inverter". You don't want to buy the modules unless you know how to modify circuits as they monitor CCFL burning out. Linear Tech has lot of app notes on that subject. Just need to add voltage multipiler stages to get to the range of HV DC you want. Each of the multiplier stage will be your voltage steps. You'll need to add your own feedback circuit to control the output if you want it regulated.
Add in sufficiently large resistor to limit the output current. Do note the working voltage rating of your *high voltage* resistors in the datasheet as resistors can be non-linear over their designed voltage range and when they are well over their design range, they will arc.
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A few verified circuits that I've built and might help you:
http://www.pocketmagic.net/high-voltage-power-supply-140kv/
http://www.pocketmagic.net/high-voltage-power-supply-50kv-for-12v-in/
http://www.pocketmagic.net/high-voltage-power-supplies/
For 10KV range you might want to go for a simple 555 oscillator and a flyback transformer (from an old TV), and rectify it so you get - , GND, +.
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