Mpp - Page 734

Joachim Gerhard · 14th September 2012, 02:39 PM

Wow, that is a much better price then at Mouser. Thanks, Holger.

pdul · 14th September 2012, 03:28 PM

I am surprised, that nobody has talked about making the listening room into a Faraday cage to complete the rf filtering

pdul · 14th September 2012, 03:46 PM

I have this trafo 230v to 230v 1200va. Will it make any difference to run the mains thru that one, regarding rf.?

Holger Barske · 14th September 2012, 03:54 PM

Depends on the transformer.
A normal transformer has reasonable capacitive coupling between primary and secondary windings, which is a pleasant path for high frequencies.
The bigger the transformer, the higher the capacitance, the bigger the problem.
There are transformers with a static shield, which will help with this.

pdul · 14th September 2012, 04:08 PM

It was not made for hifi, it was used for isolated control voltage in a big crane

So its probably not so good except for damping of spikes.

Joachim Gerhard · 14th September 2012, 04:23 PM

Maybe one time i will make actual measurements on transformers to find out how wide band different makes are.
i have a little time today .....

pdul · 14th September 2012, 04:39 PM

With isolated net, you have zero potential to ground. Is it wrong to asume that it aplies to rf and other polutions in the supply too?

Holger Barske · 14th September 2012, 05:44 PM

Yes. It is wrong

.
A transformer generally solves the galvanic part of the isolation, but capacitive coupling is another story.

Joachim Gerhard · 17th September 2012, 06:35 PM

I have a lot of BC337-40 with Hfe of 400 - 450 with no matching PNP.
When somebody here has too much BC327-40 with Hfe 400 - 450 i would like to buy or trade 200 pc.
I hope this deal is not big enough to put into vendors bazar.

pdul · 17th September 2012, 07:00 PM

Same problem here 327 hfe 300-390 and 337 460-590 all Unfairchild.
The Diotec´s has much better/more matches.

14th September 2012, 03:54 PM	#7334
Holger Barske diyAudio Member Join Date: Jan 2001 Location: Ruhrgebiet	Depends on the transformer. A normal transformer has reasonable capacitive coupling between primary and secondary windings, which is a pleasant path for high frequencies. The bigger the transformer, the higher the capacitance, the bigger the problem. There are transformers with a static shield, which will help with this. __________________ Best regards: Holger www.holgerbarske.com - Deutschsprachiges Paradise-Support-Forum

14th September 2012, 05:44 PM	#7338
Holger Barske diyAudio Member Join Date: Jan 2001 Location: Ruhrgebiet	Yes. It is wrong . A transformer generally solves the galvanic part of the isolation, but capacitive coupling is another story. __________________ Best regards: Holger www.holgerbarske.com - Deutschsprachiges Paradise-Support-Forum

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14th September 2012, 02:39 PM	#7331
Joachim Gerhard diyAudio Member Join Date: Mar 2009	Wow, that is a much better price then at Mouser. Thanks, Holger.

14th September 2012, 03:28 PM	#7332
pdul diyAudio Member Join Date: Jan 2009 Location: Copenhagen	I am surprised, that nobody has talked about making the listening room into a Faraday cage to complete the rf filtering

14th September 2012, 03:46 PM	#7333
pdul diyAudio Member Join Date: Jan 2009 Location: Copenhagen	I have this trafo 230v to 230v 1200va. Will it make any difference to run the mains thru that one, regarding rf.?

14th September 2012, 04:08 PM	#7335
pdul diyAudio Member Join Date: Jan 2009 Location: Copenhagen	It was not made for hifi, it was used for isolated control voltage in a big crane So its probably not so good except for damping of spikes.

14th September 2012, 04:23 PM	#7336
Joachim Gerhard diyAudio Member Join Date: Mar 2009	Maybe one time i will make actual measurements on transformers to find out how wide band different makes are. i have a little time today .....

14th September 2012, 04:39 PM	#7337
pdul diyAudio Member Join Date: Jan 2009 Location: Copenhagen	With isolated net, you have zero potential to ground. Is it wrong to asume that it aplies to rf and other polutions in the supply too?

17th September 2012, 06:35 PM	#7339
Joachim Gerhard diyAudio Member Join Date: Mar 2009	I have a lot of BC337-40 with Hfe of 400 - 450 with no matching PNP. When somebody here has too much BC327-40 with Hfe 400 - 450 i would like to buy or trade 200 pc. I hope this deal is not big enough to put into vendors bazar.

17th September 2012, 07:00 PM	#7340
pdul diyAudio Member Join Date: Jan 2009 Location: Copenhagen	Same problem here 327 hfe 300-390 and 337 460-590 all Unfairchild. The Diotec´s has much better/more matches.