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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets. |
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29th Oct 2019, 6:50 pm | #21 |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 13,951
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Re: NOS capacitors
There are loads of circuits out there for Neon-based capacitor-testers - basically wiring the capacitor in series with a neon, a current-limiting resistor, and a suitably-high DC voltage.
The neon should initially light brightly, dim, and then go out. If it stays bright, or dims but doesn't go out the capacitor is seriously-leaky. If it's not-so-leaky the neon will light brightly, dim, go out, and then flash periodically. The rate-of-flashing indicates just how-leaky the capacitor is; for non-electrolytic capacitors I treat anything more than one flash per minute as a condemnation. |
29th Oct 2019, 7:52 pm | #22 |
Dekatron
Join Date: Nov 2011
Location: Surrey, UK.
Posts: 4,385
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Re: NOS capacitors
I like the Mullard "mustards", too, but I can't help thinking that, as one of the first plastic film types on the market, the designers may have been playing safe as regards both insulation thickness and encapsulation quality.
"I've never come across a duff one in half-a-century" is impressive to the likes of us, but not so impressive to a production engineer guided by equipment life-cycles of a decade or less, and even less impressive to his boss! "What's cheaper, and good enough? And who decided to buy these?" .... |
29th Oct 2019, 11:05 pm | #23 |
Dekatron
Join Date: Dec 2007
Location: Haarlem, Netherlands
Posts: 4,184
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Re: NOS capacitors
Maybe, but if it was like that at Philips, they would have continued to produce tar bombs (paper capacitors) to this day (just like RIFA did). No reason whatsoever to switch to polyester as radically as they did.
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29th Oct 2019, 11:11 pm | #24 | |
No Longer a Member
Join Date: Oct 2016
Location: Maroochydore, Queensland, Australia.
Posts: 2,679
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Re: NOS capacitors
Quote:
Then when the usual suspects (like electrolytic caps placed next to a heat-sink) shorten the appliance's life, the blame lies elsewhere. Or how about a fairly specific life cycle like a battery powered NVram soldered to the pcb, they are usually gone by 15yrs, though the makers guarantee 10 years. And now flash memory "forgettory" in the PIC micro will assume the life cycling role. You have to admire a well made part though. I wonder if the Mustards were well priced at the time, or came at a premium price, it would be an interesting factoid. |
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30th Oct 2019, 1:43 am | #25 |
Dekatron
Join Date: Nov 2003
Location: Heckmondwike, West Yorkshire, UK.
Posts: 9,637
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Re: NOS capacitors
The first ones were green, not yellow. I don't think they were over engineered, just the right material for the job. A natural successor to the various (failed) attempts to reduce the cost of encapsulating paper capacitors.
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30th Oct 2019, 2:17 am | #26 |
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Join Date: Jun 2015
Location: Mareeba, North Queensland, Australia
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Re: NOS capacitors
I have never seen green ones!!. I do still have a largish collection of them though.
They are film and foil caps, not painted plastic tape. I remember paying about 10 cents for an "average" value ( say .1 uF @400 volts) when I was about 13 or 14. My income was 6 bob a fortnight back then, so cost effective? I suspect yes. Stuff I built back then is still working today ( about 55 years) so I find them ultra reliable. I did have excellent teachers who taught that keeping cool is the trick. Joe |
30th Oct 2019, 2:56 am | #27 |
Dekatron
Join Date: Dec 2007
Location: Haarlem, Netherlands
Posts: 4,184
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Re: NOS capacitors
They must have been reasonably priced as Philips seems to have dropped most of the paper product lines pretty quickly. At least for use in their own sets, but probably also production for third parties.
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30th Oct 2019, 9:43 pm | #28 |
Dekatron
Join Date: Jan 2004
Location: Newcastle upon Tyne, Tyne & Wear, UK.
Posts: 8,171
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Re: NOS capacitors
Hi Gents, they must have been a reliable component as Nalders instruments selected "mustards" for the frequency selective element in their power system frequency meters.
These were designed in in the 60's well before the Reyrolle takeover. The only proviso was that the were aged by being connected acrodd the 50Hz mains for 6 months or more before use. Ed |