Terry filter for CCPS
Finn Hammer, Thu Sept 20 2007, 06:04AMIn another thread,
Terry Fritz wrote ...
It is rated at 240mA.
The resistors will get pretty warm so plan on that.
Cheers,
Terry
It is rated at 240mA.
The resistors will get pretty warm so plan on that.
Cheers,
Terry
Terry,
Looking at a Terry filter for the CCPS, I wonder if the design point is the voltage drop across the resistors.
At 4Aavg, they should be reduced to 62.5 ohms, and dissipation would go up from 62.5W to 1000W
Seems like an awful lot of heat.
Would the filter have any effect at further reduced resistance, or should I go for a solution with inductors instead?
Cheers, Finn Hammer
Re: Terry filter for CCPS
Terry Fritz, Fri Sept 21 2007, 08:41PM
Hi Finn,
The resistors and capacitors form a low pass filter that basically burns off noise in the form of heat. 4 amps is probably way too high of current for resistors to be used unless the source impedance is low.
An inductor/capacitor filter will need some sort of resistance to bring the filter Q to about 1 (or 0.707). That might burn off a lot of heat too. I would think just a lot of big high current caps would do the trick or a true high frequency high pass filter that would not carry the DC (like a snubber).
I am not real familiar with the CCPS thread or concept so I am not sure. If high frequency noise is the concern, a super stiff high pass filter would probably be the best way to go.
BTW - The "high pass filter" I talk of is shunted across the supply so I guess it is more of a "lowpass". But basically a "snubber" circuit is what I mean.
Hope this helps or I may be totally off track. Is there an explanation on the net somewhere that explains the CCPS idea?
Cheers,
Terry
Terry Fritz, Fri Sept 21 2007, 08:41PM
Hi Finn,
The resistors and capacitors form a low pass filter that basically burns off noise in the form of heat. 4 amps is probably way too high of current for resistors to be used unless the source impedance is low.
An inductor/capacitor filter will need some sort of resistance to bring the filter Q to about 1 (or 0.707). That might burn off a lot of heat too. I would think just a lot of big high current caps would do the trick or a true high frequency high pass filter that would not carry the DC (like a snubber).
I am not real familiar with the CCPS thread or concept so I am not sure. If high frequency noise is the concern, a super stiff high pass filter would probably be the best way to go.
BTW - The "high pass filter" I talk of is shunted across the supply so I guess it is more of a "lowpass". But basically a "snubber" circuit is what I mean.
Hope this helps or I may be totally off track. Is there an explanation on the net somewhere that explains the CCPS idea?
Cheers,
Terry
Re: Terry filter for CCPS
Steve Conner, Fri Sept 21 2007, 08:48PM
Hi Terry,
A CCPS is a capacitor charging power supply, think electronic NST on steroids with a rectifier on the output
We are proposing adding a Terry filter to it, to protect the rectifier diodes, transformer windings, IGBTs etc. against kickbacks from the Tesla coil spark gap.
I would size the resistors to have half of the biggest dissipation you are comfortable with, say 25W. Then size the capacitors such that 0.5*C*v^2 times the breakrate equals another 25W. All of the energy in the Terry filter caps is dissipated in the resistors at each bang, so the total is now the 50W that you thought you could tolerate. AFAIK.
You really only need half of a Terry filter (one R and one C) if you can ground the negative end of your rectifier bridge.
Steve Conner, Fri Sept 21 2007, 08:48PM
Hi Terry,
A CCPS is a capacitor charging power supply, think electronic NST on steroids with a rectifier on the output
We are proposing adding a Terry filter to it, to protect the rectifier diodes, transformer windings, IGBTs etc. against kickbacks from the Tesla coil spark gap.
I would size the resistors to have half of the biggest dissipation you are comfortable with, say 25W. Then size the capacitors such that 0.5*C*v^2 times the breakrate equals another 25W. All of the energy in the Terry filter caps is dissipated in the resistors at each bang, so the total is now the 50W that you thought you could tolerate. AFAIK.
You really only need half of a Terry filter (one R and one C) if you can ground the negative end of your rectifier bridge.
Re: Terry filter for CCPS
Marko, Fri Sept 21 2007, 09:36PM
Would a common mode filter help? Flyback ferrite core with some insulation and two parallel windings?
Marko, Fri Sept 21 2007, 09:36PM
Would a common mode filter help? Flyback ferrite core with some insulation and two parallel windings?
Re: Terry filter for CCPS
Finn Hammer, Sat Sept 22 2007, 06:49AM
You remember Marco Denicolai`s powersupply for the Thor?
It is that basic concept.
and like this:
Erh.... not _really_ a spark gap. It is a big triggered BRISG that we are building. Had to be done
Cheers, Finn Hammer
Finn Hammer, Sat Sept 22 2007, 06:49AM
Terry Fritz wrote ...
Hi Finn,
Is there an explanation on the net somewhere that explains the CCPS idea?
Cheers,
Terry
Terry,Hi Finn,
Is there an explanation on the net somewhere that explains the CCPS idea?
Cheers,
Terry
You remember Marco Denicolai`s powersupply for the Thor?
It is that basic concept.
and like this:
Steve Conner wrote ...
Hi Terry,
We are proposing adding a Terry filter to it, to protect the rectifier diodes, transformer windings, IGBTs etc. against kickbacks from the Tesla coil spark gap.
.
Hi Terry,
We are proposing adding a Terry filter to it, to protect the rectifier diodes, transformer windings, IGBTs etc. against kickbacks from the Tesla coil spark gap.
.
Erh.... not _really_ a spark gap. It is a big triggered BRISG that we are building. Had to be done
Cheers, Finn Hammer
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