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 Another Mystery Piece of Equipment
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 Return to top of page · Post #: 1 · Written at 1:32:02 PM on 6 April 2016.
Cpsmusic's Gravatar
 Location: Melbourne, VIC
 Member since 18 February 2014
 Member #: 1507
 Postcount: 51

Hi Folks,

This device was in my Dad's workshop but it was only connected to his Hi-Fi gear.

Just wondering what it is - possibly an AC filter of some sort?


Also, what are the two metal boxes - are they some sort of capacitor (I have a bag of them)?



 Return to top of page · Post #: 2 · Written at 2:53:20 PM on 6 April 2016.
GTC's avatar
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 6014

Can't see all of the wiring by my guess is it's a passive ladder filter like this: http://www.interfacebus.com/Ladder-filter-LC-Lowpass-Filter.png

Yes, they would be capacitors, and probably oil-filled. The oil used contains BCPs -- considered carcinogenic now. Out of interest, what is printed on the one in the wooden box?

 Return to top of page · Post #: 3 · Written at 3:20:28 PM on 6 April 2016.
Cpsmusic's Gravatar
 Location: Melbourne, VIC
 Member since 18 February 2014
 Member #: 1507
 Postcount: 51

From what I can see:

2x .25 MFD
600 VDC

Bit hard to make out the rest.

 Return to top of page · Post #: 4 · Written at 4:34:10 PM on 6 April 2016.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 4348

That is actually a mains filter for getting RF & other crap off of the lines. The coils are a delay line and it is a common design.

Now! Those silver things were of a capacitor type that were in my WWII Philco BC-221-N Frequency Meter. They are oil filled & full of a toxic PCB oil. They are not an approved line capacitor for mains and of a Waxed Paper style construction.

The ones in my unit were typical of the species & had turned in to resistors like the rest of the Wax paper types do. It is highly improbable that they are any good and any Wax paper type caps in this day and age are replaced on sight.

Some of that looks like a rubber type wire and the plug tells me that it is likely of an era & age where that rubber will have perished.

Don't bother to plug it in, as far as I am concerned it is now intrinsically unsafe.

PCB is a classified substance for disposal : I.e. not in the rubbish bin.


 Return to top of page · Post #: 5 · Written at 5:31:09 PM on 10 April 2016.
Simplex's Gravatar
 Location: Bathurst, NSW
 Member since 7 August 2008
 Member #: 336
 Postcount: 336

As Marcc indicated a home made mains filter to keep noise, transient spikes and other crap from getting into hifi gear.

I bought one filter from Jaycar and mounted it in a electricians box with lead and socket in similar manner to the way your Dad did.

I was getting a "plop" every time the fridge cycled.

The best way to kill such noise is to put the filter at the device causing the interference if possible. So the transient is suppressed at the source and not radiated through the household wiring.

My fridge is permanently plugged into the filter which completely removes the "plop".


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