Cap or caps on ac inlet ?

ROVSING · 1st February 2005, 05:08 AM

Could anyone explain the difference?
I've allmost finished my first GC, but when i "stripped" an old taperecorder the other day i found that ther were 1 cap on the ac-inlet seriel on each rail instead of one parallel, is this just another solution or is it even a better solution ?
Or is it something special fore taperecorders ?

digi01 · 1st February 2005, 06:15 AM

what you mean is a EMC filter?

ROVSING · 1st February 2005, 06:46 AM

Yes that is what i mean, on f.ex. on my BZLS preamp i've mounted a cap with one leg on AC hot and one leg on AC 0 as a filter, i will do that on my gainclone too, but if the filter gets even better by mounting 1 cap on each wire i will prefere that, the problem is that my technical knowledge in electronics are very small i'm better at working with steel, wood and design, but i am trying to learn by doing.
This is probably a small problem, but i am not able to see the difference, and if you don't ask you won't get any answers.....

phn · 1st February 2005, 09:41 AM

You mean like this?

I know even less than you about electronics, so this post is as much about "self-help."

ROVSING · 1st February 2005, 09:56 AM

no more like this...

pinkmouse · 1st February 2005, 10:16 AM

Hmm, mounted in series with the mains like that they are unlikely to be caps, maybe some sort of surge protection? Any chance of a picture?

phn · 1st February 2005, 10:16 AM

Man, was I way off.

Hopefully I will have learnt more by the time I get around to my own GC.

boholm · 1st February 2005, 10:51 AM

I have only seen capacitors in series in electronics that does not require much power - just like your tape recorder.

Unless there were some diodes there too? And how big are the capacitors?

ROVSING · 1st February 2005, 11:13 AM

I will take a picture when i get home and then mail it tomorrow they are Rifa capacitors from a Technics taperecorder but i don't remember the values. I think it was something like 0.001 uF / 250v.

runebivrin · 1st February 2005, 11:19 AM

A capacitor in series with the AC inlet blocks any DC component from saturating the transformer, which can be useful to stop the transformer from humming, getting warm and using inordinate amounts of current. One or two makes no difference, unless they're electrolytic and connected with opposite polarity.

There's usually a couple of diodes across the caps, to protect in case the caps go bad.

Rune

1st February 2005, 05:08 AM	#1
ROVSING diyAudio Member Join Date: Sep 2004 Location: Fyn Odense	Cap or caps on ac inlet ? Could anyone explain the difference? I've allmost finished my first GC, but when i "stripped" an old taperecorder the other day i found that ther were 1 cap on the ac-inlet seriel on each rail instead of one parallel, is this just another solution or is it even a better solution ? Or is it something special fore taperecorders ? __________________ Frandsen

1st February 2005, 06:46 AM	#3
ROVSING diyAudio Member Join Date: Sep 2004 Location: Fyn Odense	Yes that is what i mean, on f.ex. on my BZLS preamp i've mounted a cap with one leg on AC hot and one leg on AC 0 as a filter, i will do that on my gainclone too, but if the filter gets even better by mounting 1 cap on each wire i will prefere that, the problem is that my technical knowledge in electronics are very small i'm better at working with steel, wood and design, but i am trying to learn by doing. This is probably a small problem, but i am not able to see the difference, and if you don't ask you won't get any answers..... __________________ Frandsen

1st February 2005, 10:16 AM	#6
pinkmouse diyAudio Moderator Join Date: Apr 2002 Location: Chatham, England	Hmm, mounted in series with the mains like that they are unlikely to be caps, maybe some sort of surge protection? Any chance of a picture? __________________ Al I conceive of nothing, in religion, science or philosophy, that is more than the proper thing to wear, for a while. Charles Fort

1st February 2005, 10:51 AM	#8
boholm diyAudio Member Join Date: Apr 2004 Location: Copenhagen	I have only seen capacitors in series in electronics that does not require much power - just like your tape recorder. Unless there were some diodes there too? And how big are the capacitors? __________________ Best regards Bo

1st February 2005, 11:13 AM	#9
ROVSING diyAudio Member Join Date: Sep 2004 Location: Fyn Odense	I will take a picture when i get home and then mail it tomorrow they are Rifa capacitors from a Technics taperecorder but i don't remember the values. I think it was something like 0.001 uF / 250v. __________________ Frandsen


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1st February 2005, 06:15 AM	#2
digi01 diyAudio Member Join Date: Mar 2003 Location: BEIJING	what you mean is a EMC filter?

1st February 2005, 10:16 AM	#7
phn diyAudio Member Join Date: Oct 2004	Man, was I way off. Hopefully I will have learnt more by the time I get around to my own GC.

1st February 2005, 11:19 AM	#10
runebivrin diyAudio Member Join Date: Jul 2003 Location: Huddinge, Sweden	A capacitor in series with the AC inlet blocks any DC component from saturating the transformer, which can be useful to stop the transformer from humming, getting warm and using inordinate amounts of current. One or two makes no difference, unless they're electrolytic and connected with opposite polarity. There's usually a couple of diodes across the caps, to protect in case the caps go bad. Rune __________________ Do wizards use spell checkers?

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