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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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Old 19th Oct 2021, 3:29 pm   #21
Station X
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Default Re: 2N 3055-2 ( yes -2 )

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OK I've cropped the image but have kept the upper section as it includes the headers. I am attaching 2 more versions of this page, hopefully something will work for members.

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Old 19th Oct 2021, 3:53 pm   #22
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Default Re: 2N 3055-2 ( yes -2 )

Glad it finally worked, not had that issue previously, so I must remember for any future scans of that type of data. Normal photos seem to work OK, even when I resize before uploading.

Back to the 2N3055, I hadn't looked at the Towers book for a while and totally forgot that there were so many variants, hopefully the scan will help others in finding the correct version or equivalent type for their job in hand.

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Old 19th Oct 2021, 3:53 pm   #23
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Default Re: 2N 3055-2 ( yes -2 )

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That's a really useful scan Dave. I see that the 2N3055E is the only member of the family specified by Towers listing as having Ft of 2.5 Mc/s. Does that mean that all production since about 1970 should properly be labelled 2N3055E?

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The E stands for the method used to produce the semiconductor die, Epitaxial.
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Old 19th Oct 2021, 4:25 pm   #24
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Default Re: 2N 3055-2 ( yes -2 )

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That's a really useful scan Dave. I see that the 2N3055E is the only member of the family specified by Towers listing as having Ft of 2.5 Mc/s. Does that mean that all production since about 1970 should properly be labelled 2N3055E?

Mike
The E stands for the method used to produce the semiconductor die, Epitaxial.
Indeed. But my question was - shouldn't all more recent production 2N3055s (since about 1970s) be labelled 2N3055E?

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Old 19th Oct 2021, 4:29 pm   #25
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Default Re: 2N 3055-2 ( yes -2 )

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That's a really useful scan Dave. I see that the 2N3055E is the only member of the family specified by Towers listing as having Ft of 2.5 Mc/s. Does that mean that all production since about 1970 should properly be labelled 2N3055E?

Mike
The E stands for the method used to produce the semiconductor die, Epitaxial.
Indeed. But my question was - shouldn't all recent production 2N3055s be labelled 2N3055E?

Mike
OK, then the implied answer was only if they are epitaxial construction.
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Old 19th Oct 2021, 4:36 pm   #26
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Default Re: 2N 3055-2 ( yes -2 )

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The E stands for the method used to produce the semiconductor die, Epitaxial.
Indeed. But my question was - shouldn't all recent production 2N3055s be labelled 2N3055E?

Mike
OK, then the implied answer was only if they are epitaxial construction.
I thought all recent production 2N3055s are epitaxial...
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Old 19th Oct 2021, 5:28 pm   #27
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Default Re: 2N 3055-2 ( yes -2 )

Unlikely that any recent production 2N3055s are even 2N3055s, I have a linear power supply that uses RCA pass transistors that are 1980's production by their date codes, and are 2N3055H (Homotaxial).
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Old 19th Oct 2021, 5:52 pm   #28
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Default Re: 2N 3055-2 ( yes -2 )

I was under the impression that RCA 'homotaxial' production ceased in the early to mid '70's at the latest, and that the 'H' referred to 'heavy duty' ?

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Old 19th Oct 2021, 6:07 pm   #29
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Default Re: 2N 3055-2 ( yes -2 )

My 751.1 has STC branded 3055s with '82 date codes and no suffixes. (Probably the American "Silicon Transistor Corporation")
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Old 19th Oct 2021, 6:40 pm   #30
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Default Re: 2N 3055-2 ( yes -2 )

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I was under the impression that RCA 'homotaxial' production ceased in the early to mid '70's at the latest, and that the 'H' referred to 'heavy duty' ?

Alan
Yes, according to one of the Cricklewood data sheets, the "H" stands for heavy duty/ruggedised. Many (reputable) sources seem very confused, and readily substitute 2N3055 data sheets for 2N3055H, and seem to switch arbitrarily between 800 kc/s and 2.5Mc/s for Ft.

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Old 19th Oct 2021, 7:08 pm   #31
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Default Re: 2N 3055-2 ( yes -2 )

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From memory, back in 1971 I used a lot of Motorola 2N3055s and was told by the supplier (Celdis Ltd, of Reading) that the Motorola aluminium cased 2N3055s were filled with silicon grease for added reliability and must say I had very few failures when making amplifiers for the disco world.
I then started using 2N3773s as they could handle more power and a higher Ce voltage; 120 volts as opposed to the 3055 of a mere but very respecable 70 volts.
I am sure I still have a few NOS Motorola versions from the 70s. I used to purchase them in trays of 100 at a time.
If I can find them, I will pm you for your address as I no longer need them.
Failing that I would fit 2N3773s. Similar hfe and frequency range.
That is extremely generous of you. For matching I used to own an AVO CT537, but that, along with lots of other things , went when I moved abroad 20 years ago. At the moment I'm reduced to a couple of DMMs, assorted resistors and a car battery! Not sure what I need? to do for pms.
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Old 19th Oct 2021, 7:30 pm   #32
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Default Re: 2N 3055-2 ( yes -2 )

Amps are remarkably flexible about transistors, so you can usually put an MJ15003 in place of 2N3055 with no problem. But the MJ15003 is a 20 amp part rated at 140v. The 2N3055 is a 15 amp part rated at 60v, though some may carry a higher voltage rating or at least be selected for it. So you cannot put 2N3055 in place of MJ15003 in most places.

Other than maybe some REALLY old first designs, I don;t recall 2N3055s in Peavey amps. I know they used them early on, but I don;t recall in what. MJ15003 was the workhorse of PV amp for a long time.
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Last edited by nutteronthebus; 19th Oct 2021 at 7:30 pm. Reason: spelling
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Old 19th Oct 2021, 8:48 pm   #33
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Default Re: 2N 3055-2 ( yes -2 )

There are plenty of fakes around, had some conduct about 500mA max. Cut the top off of one, the die was about 3mm square as opposed to about 7mm for a genuine one!!!
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Old 20th Oct 2021, 12:22 pm   #34
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Default Re: 2N 3055-2 ( yes -2 )

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I tried a straight swap to MOSFET's in a power supply and it didn't work, so probably not.

As others have said, replacing old 2N3055's with modern ones may entail some taming with bypass caps to keep them stable.
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Old 20th Oct 2021, 9:22 pm   #35
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Default Re: 2N 3055-2 ( yes -2 )

That's OK, I did work out what was happening, let us know how you get on (and I spent a fair bit of time around those parts as a child).
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Old 20th Oct 2021, 9:42 pm   #36
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Default Re: 2N 3055-2 ( yes -2 )

As a more general observation, the 2N3055 was evidently of sufficient importance to have warranted an IEEE paper on its history, namely:

“The 2N3055: A Case history”; John N. Ellis and Vince S. Osadchy; IEEE 2001.

I don’t think that it is stretching “fair use” too much to quote the abstract and the concluding paragraph from that paper:


Abstract—The 2N3055 power transistor was introduced by the Radio Corporation of America (RCA) in the early 1960s. It was one of the first silicon power transistors, offered unrivaled second breakdown immunity and found many applications particularly in audio power amplifiers and linear power supplies. Other companies tried to copy it with varying degrees of success: one company acknowledges it now by naming a power MOSFET after it. We trace its history, manufacture and eventual decline against pressure from competing technologies. Modern simulation tools have been used to investigate the operation of the device which illustrate its good, and not so good, features. We also relate its geometry to a SPICE model. Neither of these tools would have been available to the original developers. We propose that this transistor be given a place in the archives of history, ranked alongside other famous devices of the 20th century such as the 300B tube.

Concluding paragraph:

The popularity that the 2N3055 had, though, in its day, must surely be noted by the fact that other manufacturers offered similar devices, some with the “3055” name, and PNP complements using the name “2955.” At least one other manufacturer used the term “single diffused,” which had become associated with the high temperature drive-in of the 2N3055. But this claim referred to an emitter drive into an epitaxial base. One manufacturer has since named a power MOSFET after it, copying some of the pertinent device specifications. We believe that this demonstrates the industry’s acknowledgment to perhaps the world’s most popular power transistor of its time, if not in the 20th century


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