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General Vintage Technology Discussions For general discussions about vintage radio and other vintage electronics etc. |
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18th Sep 2019, 11:59 pm | #1 |
Hexode
Join Date: Mar 2018
Location: Bishop Auckland, County Durham, UK.
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Mullard glass transistors
I recently bought an early 1960s Perdio Carnival transistor radio in nice condition and all working. Looking inside I was surprised to find that someone had carefully swapped the original Mullard glass germanium transistors (OC44 OC45 OC71) for equivalent Russian types. I wondered if the Mullard glass devices are going to become prize possessions along the lines of PX4 triode valves!
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19th Sep 2019, 12:41 am | #2 |
Moderator
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Re: Mullard glass transistors
They already are.
Certain guitar effects pedals used them back in the day. Modern guitarists lust after them because if they can only manage to get some of the original type transistors they can build a pedal and get that special magical tone that will soon make them as rich and famous as <insert name here> So they do grab transistors from old portables. NOS germmanium devices go for silly money on auction sites. But I've not come across them fitting russian replacements to make the radio go again... it usually goes in the bin. David
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19th Sep 2019, 12:50 am | #3 |
Octode
Join Date: Jul 2011
Location: Staffordshire Moorlands, UK.
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Re: Mullard glass transistors
Sorry David, I've got to disagree I'm afraid. Most guitarists (and I'm one of em) just want to find a 'sound' and these old transistors do that, well some of them do and they are highly variable, but then musical instruments by their very nature are like that. It's nowt to do with being rich and famous - if that's your ambition then best go on BGT or X Factor etc.
Cheers, Steve.
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19th Sep 2019, 1:19 am | #4 |
Dekatron
Join Date: Apr 2012
Location: Worksop, Nottinghamshire, UK.
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Re: Mullard glass transistors
NOS glass transistors go for such silly money that they now have to be treated like money so much so that they have to be kept in money bags
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19th Sep 2019, 4:39 am | #5 | |
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Re: Mullard glass transistors
Quote:
http://www.worldphaco.com/uploads/Gretschdoc.pdf The most suited American made device is the 2N2613 (designed much like the UK/European AC107) for low noise tape deck preamps. The better made American effects pedals used these as did Gretsch. Realizing this I bought up a large number of them before this was common knowledge to make replica Gretsch Treble boost amplifiers, which I have supplied to very few including a guitarist from Dire Straits because I'm not normally in the business of making and selling electronic apparatus. Of course the Europeans and the Americans were not the only ones to make low noise audio germanium transistors suited to the task at the time in the mid 1960's. Due to the fact that the Japanese basically pioneered battery portable audio tape recorders in that era they set their semiconductor houses to the task of manufacturing low noise germaniums for audio. There are quite a few examples such as the 2SB440. The Americans got onto these types and started using them in pairs 2SB439/440 in the front ends of their 8 track tape players. Last edited by Argus25; 19th Sep 2019 at 5:08 am. Reason: typo |
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19th Sep 2019, 7:03 am | #6 |
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Re: Mullard glass transistors
My tongue was firmly in cheek, my brother can be found in 'The best little blues band in Batley' and distortion/vintage pedals is an in-family wind-up. I gave him a Wien bridge oscillator and matching distortion meter 'So he could check he was getting enough'
But, still, at the prices the NOS ones are fetching, there must be some very powerful motivation at work to spring that much money out of people. I used to know Matt Mathias, the man behind Matamps, also sold under the Orange brand. He had a steady stream of quite well known names come into his shop on King Street, Huddersfield. David
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19th Sep 2019, 10:05 am | #7 |
Heptode
Join Date: Jul 2010
Location: Wellington, New Zealand.
Posts: 653
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Re: Mullard glass transistors
But did you make sure your brother took the 'tone sucking capacitors' out of his electric guitar?? It is a well known fact that musicians who appear in pubs where the patrons are usually a little merry will be immediately booed for their sound if the caps have not been changed AND their amps do NOT have the NOS long plate 12AX7's. Go into any pub and you will hear 'Oh my GOD he's using a non gold plated, oxygen-free lead for his amp!!' or ' what a terrible sound - must be his Russian EL34 equivalents.' -
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19th Sep 2019, 10:11 am | #8 |
Heptode
Join Date: Jul 2010
Location: Wellington, New Zealand.
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Re: Mullard glass transistors
Speaking of Mullard glass transistors - did anyone here figure out a good way to open a later OC71 and get rid of the opaque goo so it was a phototransistor? The older ones you could scrape the black paint off, but not the later ones. I had a bit of success but found it was far to easy to damage the inside contents or connections.
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19th Sep 2019, 11:22 am | #9 |
Dekatron
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
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Re: Mullard glass transistors
Stick it in a centrifuge AKA mum's spin dryer
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19th Sep 2019, 11:29 am | #10 |
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Re: Mullard glass transistors
Black silicone grease marks on the next load of washing? That's you in deep trouble, Chris.
David
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Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done |
19th Sep 2019, 12:23 pm | #11 |
Dekatron
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Re: Mullard glass transistors
I have a couple of the ones that you can scrape the paint off to get a poor man's phototransistor. Apparently they really are phototransistors, but reject in some way: http://www.wylie.org.uk/technology/s...rd/Mullard.htm
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19th Sep 2019, 1:02 pm | #12 | |
Nonode
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Location: Folkestone, Kent, UK.
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Re: Mullard glass transistors
Quote:
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19th Sep 2019, 1:34 pm | #13 | |
Octode
Join Date: Dec 2017
Location: Morden, Surrey, UK.
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Re: Mullard glass transistors
Quote:
The spin dryer was a well known trick mentioned Practical Wireless, I seem to remember. I think I have some early unpainted no opaque goo samples somewhere. |
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19th Sep 2019, 3:30 pm | #14 | |
Dekatron
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Re: Mullard glass transistors
Quote:
You don't have to open the package, just move the goo away from the chip. Wasn't the goo blue? That's where I would have seen the idea!
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19th Sep 2019, 5:11 pm | #15 | |
Nonode
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Re: Mullard glass transistors
Quote:
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21st Sep 2019, 1:03 am | #16 | ||
Heptode
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Re: Mullard glass transistors
Quote:
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21st Sep 2019, 1:10 am | #17 |
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Re: Mullard glass transistors
Wasn't the red dot the collector?
I have hundreds of wrong way round glass transistors Joe |
21st Sep 2019, 1:57 am | #18 |
Dekatron
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Re: Mullard glass transistors
I was told that the goo was silicone grease. When trich was still around, that was quite good at dissolving silicone grease.
B
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21st Sep 2019, 8:30 am | #19 |
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Re: Mullard glass transistors
red16v's mother has a lot to answer for!
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21st Sep 2019, 1:24 pm | #20 |
Dekatron
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Re: Mullard glass transistors
The red dot is the collector, but there is also a difference in the leadout spacing. They will work either way round, but with greatly reduced gain, maybe that's what is being tested.
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