Author Topic: CCFL inverter as basis for easy low-current 500V DC supply?  (Read 1664 times)

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Offline mmagin

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CCFL inverter as basis for easy low-current 500V DC supply?
« on: April 30, 2016, 04:59:38 pm »
Would there be any problems with using something like a TDK CXA-L10L
 (900V AC open circuit), bridge rectifier (1.5kv rated diodes), high voltage film capacitor, and a resistor+string of zeners shunt regulator to achieve regulated 500 V DC at a couple milliamps?

I mostly know it's not their usual load, so I'm wondering if that would present any problems.
 

Offline mathias

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Re: CCFL inverter as basis for easy low-current 500V DC supply?
« Reply #1 on: May 01, 2016, 04:37:15 pm »
Nope, should work like a charm. I've built one to power up my PMT at 1.6kV at 250uA (about). Not a problem there.
 

Offline evb149

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Re: CCFL inverter as basis for easy low-current 500V DC supply?
« Reply #2 on: May 01, 2016, 06:55:54 pm »
Make sure the diodes are fast enough.
Also why use the zeners to regulate when you could just send feedback control to the primary side bridge by optocoupler isolation with a TL431 or similar as offline PSUs typically use.

 

Online wraper

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Re: CCFL inverter as basis for easy low-current 500V DC supply?
« Reply #3 on: May 01, 2016, 07:00:44 pm »
Sounds like very inefficient and awkward way to do this.
 

Offline Marco

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Re: CCFL inverter as basis for easy low-current 500V DC supply?
« Reply #4 on: May 01, 2016, 07:07:06 pm »
Would there be any problems with using something like a TDK CXA-L10L
 (900V AC open circuit), bridge rectifier (1.5kv rated diodes), high voltage film capacitor, and a resistor+string of zeners shunt regulator to achieve regulated 500 V DC at a couple milliamps?

You can use an adjustable linear regulator to modulate the input voltage to the inverter, with the feedback provided by a divider from the high voltage output. Dodgy hack, but quite common.
 

Offline mmagin

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Re: CCFL inverter as basis for easy low-current 500V DC supply?
« Reply #5 on: May 01, 2016, 07:37:58 pm »
Make sure the diodes are fast enough.
Also why use the zeners to regulate when you could just send feedback control to the primary side bridge by optocoupler isolation with a TL431 or similar as offline PSUs typically use.

Thanks for the idea.  But I'm less concerned about efficiency than having a fairly clean output. 
Very good point about the diodes though.
 

Offline Zero999

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Re: CCFL inverter as basis for easy low-current 500V DC supply?
« Reply #6 on: May 02, 2016, 03:06:01 pm »
The TL431 will give fairly good regulation but is only rated to 36V but when used with a cascode it can work up to much higher voltages.

 
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Offline mmagin

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Re: CCFL inverter as basis for easy low-current 500V DC supply?
« Reply #7 on: May 02, 2016, 05:46:47 pm »
When reading evb149's post, I was imagining more something like a 200:1 resistive voltage divider to bring the 500 volts down to 2.5 volts and using the TL431 as a comparator + voltage reference, which would then drive the LED in an optocoupler.
 


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