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Other Vintage Household Electrical or Electromechanical Items For discussions about other vintage (over 25 years old) electrical and electromechanical household items. See the sticky thread for details. |
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23rd Nov 2020, 2:52 am | #1 |
Tetrode
Join Date: Sep 2020
Location: Blue Mountains City, New South Wales, Australia.
Posts: 51
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Static suppressor mains plug
Hi folks,
I have in my possession a three pin mains plug. It was made by Clipsal, an Australian manufacturer of Bakelite and other electrical stuff. The plug bears the legend- "Auto Iron Static Suppressor" and I think it came about from dutiful housewives ironing the new synthetic fabrics mid century, and getting zapped. The plug is mostly normal looking, with the exception of there being a chamber beside the cord opening. This chamber has evidence of something waxy having once dwelt within. The chamber is approximately round; 20mm (3/4") diameter and about the same deep. I don't think this plug ever did anything to 'suppress' static. I believe it discharged the static to ground. But how did that happen via a capacitor. Maybe it was some other wax coated device, but what? The plug has been following me around since the '80's because I wanted to know how it originally worked, and until then I won't let it go. Your thoughts on what the waxy thing might have been, and how it discharged static without a current from the mains would be appreciated. Curious minds want to know. Clay.
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23rd Nov 2020, 3:55 am | #2 |
Moderator
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,800
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Re: Static suppressor mains plug
Are Australian irons usually earthed via the third pin? If so, the iron will not become statically charged, though things around it and people may do so, and when touching an earthed object (like a 3-wire iron) will get a shock as they discharge themselves.
Vehicle tyres were made conductive many decades ago, but people charge themselves walking and get a discharge shock on touching the door handle. The solution is resistive shoes, but people buy earthing accessories for the vehicle, saying it shocked them. So you cannot trust people when they say what they got a shock from. Snake oil products were common. Another possibility is that the waxy thing is a suppression capacitor to prevent radio interference from the iron's thermostat contacts. A lot of people called that 'static' David
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23rd Nov 2020, 8:57 am | #3 |
Tetrode
Join Date: Sep 2020
Location: Blue Mountains City, New South Wales, Australia.
Posts: 51
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Re: Static suppressor mains plug
Yes I think that you're right. The reference to "static" is a misnomer. I recall people calling any sounds that weren't expected static when I was a bit younger.
Valve equipment seems to be particularly sensitive to stray RF crackles and pops. I spent some time once finding out about X and Y capacitors for noise suppression in motorised appliances from the days of yore. Thanks for that, and come join me on the spectrum. We can get overly literal together. Clay.
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23rd Nov 2020, 9:36 am | #4 |
Moderator
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,800
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Re: Static suppressor mains plug
If you look at the EMC regs and the accompanying specs for the measuring receivers you'll see that a lot of it originated around the assumption of the sources being sparking commutators and thermostats. The measuring receivers have to have a dramatic amount of dynamic range to not compress the total power in a pulse, while measuring the power in a small amount of bandwidth, and the time-constants of the quasi-peak detector are chosen for sensitivity to pulses. The continuous tones spewed by micropocessor systems were seen through pulse-coloured goggles.
David
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23rd Nov 2020, 9:45 am | #5 |
Triode
Join Date: Oct 2008
Location: Perth, Western Australia, Australia
Posts: 39
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Re: Static suppressor mains plug
I have a NOS clipsal bakelite plug. It contains a o.1 uF wax paper capacitor wired across active and neutral.
The idea was to place them on noisey equipment like washing machines and fridges etc to reduce electrical interference to radio reception. I'm sure they would go off with a nice bang as the capacitors became leaky. See attached photos
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Best Regards Nigel VK6CPU Perth, Western Australia Last edited by red-duck; 23rd Nov 2020 at 10:14 am. Reason: Improve description |
23rd Nov 2020, 12:20 pm | #6 |
Dekatron
Join Date: Mar 2008
Location: St. Frajou, l'Isle en Dodon, Haute Garonne, France.(Previously: Ellesmere Port, Cheshire, UK.)
Posts: 3,177
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Re: Static suppressor mains plug
Hi,
I've got a couple of old suppressor plugs. These are: An Aerialite 5 amp round pin adaptor. A Belling Lee unit with a short flex and two earth terminals, And a Dubilier wired on plug in rubber. I bought them for a couple of bob each as a teenager, and knew nothing of capacitors deteriorating with age. Was I surprised when they went BANG! upon plugging them in! Lesson learned! Cheers, Pete.
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23rd Nov 2020, 12:24 pm | #7 |
Tetrode
Join Date: Sep 2020
Location: Blue Mountains City, New South Wales, Australia.
Posts: 51
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Re: Static suppressor mains plug
David, I think you're talking about those droning ssounds that my father told me were car ignition noise. I remember thinking "geez, somebody must be driving round and round us". It never seemed to vary much once tuned in. He also once said "It's Japan". I dunno either.
Mr Duck, That is the very thing, only mine has never had a capacitor in it while I've known it. Thanks for revealing a little mystery. Clay.
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23rd Nov 2020, 9:23 pm | #8 | |
Tetrode
Join Date: Sep 2020
Location: Blue Mountains City, New South Wales, Australia.
Posts: 51
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Re: Static suppressor mains plug
Quote:
At least you weren't hurt by the things. It'd be a tragedy for them to suppress an extractor fan. Clay.
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25th Nov 2020, 3:12 pm | #9 |
Dekatron
Join Date: Mar 2008
Location: St. Frajou, l'Isle en Dodon, Haute Garonne, France.(Previously: Ellesmere Port, Cheshire, UK.)
Posts: 3,177
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Re: Static suppressor mains plug
Hi,
In days of yore when these things were new, there was a lot of wireless interference from trams as well as car and motorbike ignition. Thus much greater need then than now. Cheers, Pete.
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25th Nov 2020, 10:10 pm | #10 |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 13,952
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Re: Static suppressor mains plug
The idea of 'filtered plugs' continues to this day: my 'intelligent' lead-acid battery-charger bought this-decade comes with a Panasonic 'filtered plug' - whose underside suggests that the filtering is a common-mode choke on the L and N conductors.
I guess this was a quick-and-simple way to comply with conducted-EMI regulations. |
25th Nov 2020, 10:53 pm | #11 |
Dekatron
Join Date: Mar 2008
Location: St. Frajou, l'Isle en Dodon, Haute Garonne, France.(Previously: Ellesmere Port, Cheshire, UK.)
Posts: 3,177
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Re: Static suppressor mains plug
Hi,
We had a Philips CRT telly back in the 90s that was fitted with a filtered plug. I wanted to power it, the VCR, the digibox and a lamp from one of those miniature mains distribution strips that were all the rage back then. So I cut the plug off to no apparent detriment. When we moved to France, we bought a new DVD/VHS combo that also had a filtered two pin plug. So, yes, filtered plugs thrive still! Cheers, Pete.
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