Keantoken's CFP cap multiplier - Page 90

rensli · 02:02 PM

Some fotos:

Filter capacitors are all the same brands in LM and k-mult filter-bank.
All samwha-s, dirty cheap. Capacitance amount is also the same 2200uf + 2x 470uF.

Sound still so different

Krissz80 · 22nd December 2015, 03:20 PM

Hi all!

I'm new here, and I have a problem with K-multi (positive version).
I've built the K-multi width BD140-16 and 1 piece of 1N4148 diode.
And I've put in the LED in opposite direction (but theoretically it should not make any difference).

In addition I use a 10nF X7R between the B-E leg of the BC337, and I use one 100nF X7R parallel to each elektrolite capacitor.

The input is voltage came from a stabilizator circuit width LM1084.
This is it's output characteristic measured by Scope.
The output is 12v 1,2A (load resistance was 10 ohm 20W).
After I connected the K-multi to the stabilizator circuit I got the following result measured by Scope.

Can anybody tell me why is it have 25MHz sinus noise on it.

av-trouvaille · 19th February 2016, 11:09 AM

It seems up to now, the K-multiplier presupposes a power supply with C-filter to smooth the DC input voltage (so an elco of significant capacitance after the bridge rectifier). In terms of function a K-multiplier might be seen as a substitute for a choke. So, the K-multiplier as an electronic choke. Would it be allowed to use a K-multiplier as a choke-input filter? That is, a K-multiplier right after the diode bridge, and the smoothing C after the K-multiplier?
I only ask whether it is technically allowed, not if it would be the optimal place.

keantoken · 19th February 2016, 06:33 PM

A large inductor right after the rectifiers can see extreme ripple and negative voltage at the input. This is far beyond the scope of the KM. There must be at least enough capacitance at the input to bring ripple down to it's working range.

av-trouvaille · 19th February 2016, 07:19 PM

Yes, I am aware that a large inductor right after the rectifiers can see extreme ripple and negative voltage at the input. I notice that in the choke input filters for my tube amps. But its peak would diminish fast as soon as current is drawn. Is it an option to simply add a zener of appropriate voltage between the rectifier and the K-multiplier to tame the peak?

keantoken · 19th February 2016, 07:26 PM

Quote:

Originally Posted by Krissz80

Hi all!

I'm new here, and I have a problem with K-multi (positive version).
I've built the K-multi width BD140-16 and 1 piece of 1N4148 diode.
And I've put in the LED in opposite direction (but theoretically it should not make any difference).

In addition I use a 10nF X7R between the B-E leg of the BC337, and I use one 100nF X7R parallel to each elektrolite capacitor.

The input is voltage came from a stabilizator circuit width LM1084.
This is it's output characteristic measured by Scope.
The output is 12v 1,2A (load resistance was 10 ohm 20W).
After I connected the K-multi to the stabilizator circuit I got the following result measured by Scope.

Can anybody tell me why is it have 25MHz sinus noise on it.

Sorry I missed this. Can you tell me why you made those changes? If anything the 10nF cap should go on the B-E of the BD140. And I think I have seen more than one KM using the BD140 that oscillated.

The KM should have capacitors close to both the input and output, but 100nF film caps are unnecessary and sometimes will even cause oscillation.

keantoken · 19th February 2016, 07:32 PM

Quote:

Originally Posted by av-trouvaille

Yes, I am aware that a large inductor right after the rectifiers can see extreme ripple and negative voltage at the input. I notice that in the choke input filters for my tube amps. But its peak would diminish fast as soon as current is drawn. Is it an option to simply add a zener of appropriate voltage between the rectifier and the K-multiplier to tame the peak?

The KM would have to turn on and off to charge the reservoirs, and a zener does not store power and so cannot support the input voltage of the KM when input is low. A zener to reduce the positive peaks would either short the rectifier or it would go across the KM, effectively bypassing it and ruining the goal of filtering.

av-trouvaille · 19th February 2016, 08:56 PM

Thanks for clarifing. No choke input with the K-multiplier for me, then.

av-trouvaille · 21st February 2016, 01:44 PM

Another question to explore the versatility of the K-multiplier, when allowed.
The current capability of the K-multiplier is limited to about 1A. Earlier you mentioned it is hard to design for more current.
Would it be feasable to increase the current capability by putting two K-multipliers in parallel?

keantoken · 21st February 2016, 02:13 PM

The power can be increased by using parallel degenerated transistors. However you can overload the driver.

19th February 2016, 06:33 PM	#894
keantoken diyAudio Member Join Date: Aug 2006 Location: Texas	A large inductor right after the rectifiers can see extreme ripple and negative voltage at the input. This is far beyond the scope of the KM. There must be at least enough capacitance at the input to bring ripple down to it's working range. __________________ The Kmultiplier rail filter! -=- The Simple Kuartlotron Superbuffer! Need something built, repaired or modded? PM me and ask what I can do!

21st February 2016, 02:13 PM	#900
keantoken diyAudio Member Join Date: Aug 2006 Location: Texas	The power can be increased by using parallel degenerated transistors. However you can overload the driver. __________________ The Kmultiplier rail filter! -=- The Simple Kuartlotron Superbuffer! Need something built, repaired or modded? PM me and ask what I can do!

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22nd December 2015, 03:20 PM	#892
Krissz80 diyAudio Member Join Date: Dec 2015	Hi all! I'm new here, and I have a problem with K-multi (positive version). I've built the K-multi width BD140-16 and 1 piece of 1N4148 diode. And I've put in the LED in opposite direction (but theoretically it should not make any difference). In addition I use a 10nF X7R between the B-E leg of the BC337, and I use one 100nF X7R parallel to each elektrolite capacitor. The input is voltage came from a stabilizator circuit width LM1084. This is it's output characteristic measured by Scope. The output is 12v 1,2A (load resistance was 10 ohm 20W). After I connected the K-multi to the stabilizator circuit I got the following result measured by Scope. Can anybody tell me why is it have 25MHz sinus noise on it.

19th February 2016, 11:09 AM	#893
av-trouvaille diyAudio Member Join Date: Aug 2003 Location: Near Rotterdam	It seems up to now, the K-multiplier presupposes a power supply with C-filter to smooth the DC input voltage (so an elco of significant capacitance after the bridge rectifier). In terms of function a K-multiplier might be seen as a substitute for a choke. So, the K-multiplier as an electronic choke. Would it be allowed to use a K-multiplier as a choke-input filter? That is, a K-multiplier right after the diode bridge, and the smoothing C after the K-multiplier? I only ask whether it is technically allowed, not if it would be the optimal place.

19th February 2016, 07:19 PM	#895
av-trouvaille diyAudio Member Join Date: Aug 2003 Location: Near Rotterdam	Yes, I am aware that a large inductor right after the rectifiers can see extreme ripple and negative voltage at the input. I notice that in the choke input filters for my tube amps. But its peak would diminish fast as soon as current is drawn. Is it an option to simply add a zener of appropriate voltage between the rectifier and the K-multiplier to tame the peak?

19th February 2016, 08:56 PM	#898
av-trouvaille diyAudio Member Join Date: Aug 2003 Location: Near Rotterdam	Thanks for clarifing. No choke input with the K-multiplier for me, then.

21st February 2016, 01:44 PM	#899
av-trouvaille diyAudio Member Join Date: Aug 2003 Location: Near Rotterdam	Another question to explore the versatility of the K-multiplier, when allowed. The current capability of the K-multiplier is limited to about 1A. Earlier you mentioned it is hard to design for more current. Would it be feasable to increase the current capability by putting two K-multipliers in parallel?