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ROVSING 1st February 2005 05:08 AM

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 ?


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.....:confused:

phn 1st February 2005 09:41 AM

2 Attachment(s)
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

2 Attachment(s)
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.:D

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.


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