Maker Pro
Maker Pro

MOSFET output stage

E

Eeyore

Jan 1, 1970
0
Michael A. Terrell said:
The 3055 was developed for linear power supplies, so it didn't need a
high fT.

True enough, except Motorola's were faster anyway. Using the wrong brand in hobby
kits caused many a burnt out output stage.

Eventually I think the slower parts got an H suffix as in RCA's 'hometaxial' process.


It was scaled down from the RCA 40411, which was a 100 volt
device, VS a 60 volt, cheaper device. The 40411 was used in some audio
amps in some early RCA semiconductor data books. In fact, the 60 watt
amplifier used the 40406, 40407, 40408, 40409, 40410, and a pair of
40411 transistors, and a couple diodes to sense the temperature of the
heatsinks. I built a PA amp from that sample design in the late '60s.
It, and a preamp were also built on my first hand made PC boards.

I know the very one and still have that handbook. I built one too. The little
heatsinks welded onto the drivers were an intriguing novelty that never caught on.

In the UK, WEM 100W PA and instrument amps were based on that design for years. They
got 100W by using 6 ohm speakers !

Graham
 
J

JosephKK

Jan 1, 1970
0
So what. Anyone who participates in the newsgroups has a mental
disorder. Normal people have no interest for that; they have sex, pray
God, take precarious mortgages and watch TV. This is what they call
"having a life".

VLV

Speaking for yourself i see. Many of us here have work, equivalent
obligations, are raising families (sometimes the grandkids), and many
other things. That we are an odd minority i cannot disprove.
 
E

Eeyore

Jan 1, 1970
0
Arny said:
According to my friend, RCA tried various ruses to come up with enough
40411-type devices, but could never equal their original product. He sold a
ton of amps that were not durable and was forced out of business.
Eventually, he started cutting open devices, both old and new, and found
results similar to what we've seen far more recently with counterfeit
transistors.. It was his opinion that RCA was sort of counterfeiting their
own product.

Seen that with the RCA410 too which they sold as replacement MJ410s. It took
thumbscrews to get them to admit they contained dies from 3 seperate lines. A
bright tech noticed by the way that there were 3 'hard codes' stamped on the
case and 2 of them gave trouble.

The 410s were just used as fastish drivers, we were using the 2N3773 by then as
main output devices. Seemed solid enough. If they'd been around at the time,
they might have saved your friend's company.

Graham
 
P

Phil Allison

Jan 1, 1970
0
"Arny Krueger"
I had a business partner who, in an earlier venture manufactured SS power
amps for professional use. He based his top-of-the-line products on the
40411. There was also an even more robust device called the 411. Again,
my memory of this is hazy as this was in the late 60s.

According to him, he discovered that the 404xx series of devices were
mostly sold for automotive uses, such as SS ignition modules. For a while
RCA was making these parts literally by the millions. Product consistency
was a problem, which they were very effective at exploiting. The
middle-of-the-road parts went to the car companies under proprietary part
numbers.

** So the auto industry bought only " middle-of-the-road parts " ??

Dear oh dear ......



...... Phil
 
E

Eeyore

Jan 1, 1970
0
Michael A. Terrell said:
I used a lot of 2N3773 to replace 40411, and some other 100 volt
transistors. I think I still have one pair left in stock. :)

They were such good replacements for almost all the (predominantly npn) output
devices of the day that I may have about half to a third of a tray of them lying
about somewhere still !

Graham
 
E

Eeyore

Jan 1, 1970
0
Michael A. Terrell said:
I used a lot of 2N3773 to replace 40411, and some other 100 volt
transistors. I think I still have one pair left in stock. :)

Oh and the 3773 had a 140V rating with correspondingly larger SOA IIRC.

Modern MJ1502Xs make it look silly now but it was THE high power audio output device
of the day.

Graham
 
E

Eeyore

Jan 1, 1970
0
Arny said:
To shed a little more light:

http://www.ck722museum.com/history/rca/OralHistory/Meisel/Meisel_Page3.htm

"After several chip design changes and some significant package cost
reductions the 2N1486 and 2N1490 migrated into the 2N3054 and 2N3055 which
became industry workhorse standards. The package redesigns were done by Milt
Grimes. The 2N3055 was the first multi-amp silicon power transistor to sell
for less than one dollar! It was a huge success in the power supply market.
In 1965, the team of Design, Production, and Applications engineers who
launched these devices got RCA Electronic Components Achievement Awards,
which were quite generous."

I'm not an IEEE member, but this relevant article is online for those who
are:

http://ieeexplore.ieee.org/Xplore/login.jsp?url=/iel5/16/20748/00960371.pdf?arnumber=960371

"
The 2N3055: a case history
Ellis, J.N.; Osadchy, V.S.
Electron Devices, IEEE Transactions on
Volume 48, Issue 11, Nov 2001 Page(s):2477 - 2484
Digital Object Identifier 10.1109/16.960371

Summary: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 unrivalled 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
"

Orange ? or was it Wem ? made probably the world's first SS 1kW amplifier using them IIRC. I
was called the Killerwatt or somesuch. Because the supply rails were so low the load had to be
something like one or two ohms, unheard of in those days, but acheived simply by multiple
paralleled speakers.

Graham
 
P

Phil Allison

Jan 1, 1970
0
"Eeysore"
Orange ? or was it Wem ? made probably the world's first SS 1kW amplifier
using them IIRC. I
was called the Killerwatt or somesuch.


** This is a schem of the largest power amp made by WEM - a 100watt @ 6ohm
slave.

http://www.vintagehofner.co.uk/britamps/watkins/schematics/100poweramp75.html

This history from Charlie Watkins himself backs up the fact:

http://www.wemwatkins.co.uk/history.htm


The "slave" amps made by " Orange " used 4 x EL34s.

http://www.orangefg.com/



..... Phil
 
P

Phil Allison

Jan 1, 1970
0
"Jan Panteltje"
"Phil Allison"
Nice, note the foldback current limiting!


** Yep - it would have saved the output BJTs from a short circuit load
condition.

However - it is not so nice if you NEED the amp to drive even a moderately
reactive speaker load to full power - cos then you get huge spike voltages
generated by the output stage when the zero voltage current limit of under 3
amps was reached.

The only thing that likely saved it in practice was the fact that woofers
with giant magnets & very low Qt numbers mounted in undersized reflex
cabinets were NOT commonplace in the early 1970s.



...... Phil
 
E

Eeyore

Jan 1, 1970
0
Phil said:
"Eeysore"

** This is a schem of the largest power amp made by WEM - a 100watt @ 6ohm
slave.

http://www.vintagehofner.co.uk/britamps/watkins/schematics/100poweramp75.html

This history from Charlie Watkins himself backs up the fact:

http://www.wemwatkins.co.uk/history.htm

The "slave" amps made by " Orange " used 4 x EL34s.

http://www.orangefg.com/

Orange made amps with 4 x KT88s too. I had to service one with KT88s that had the
one with a molten anode.

I think it must have been an Orange special. It was in one of their catalogues
btw. This is late 60s IIRC.

Graham
 
P

Phil Allison

Jan 1, 1970
0
"Eeysore Criminal Nut Case LIAR "

I think it must have been an Orange special.


** Yaaawwwnnnnnnnnnnnnnnn ....


Maybe it was the infamous Clockwork Orange ??

Or its nemesis the Clockwork Lemon ???

ROTFL ................


It was in one of their catalogues btw. This is late 60s IIRC.


** So put up or shut up -

YOU RIDICULOUS FUCKING LIAR !!!




..... Phil
 
E

Eeyore

Jan 1, 1970
0
Phil said:
"Eeysore Criminal Nut Case LIAR "


** Yaaawwwnnnnnnnnnnnnnnn ....

Maybe it was the infamous Clockwork Orange ??

Grow up Phil.

Graham
 
P

Phil Allison

Jan 1, 1970
0
"Eeysore Criminal Nut Case LIAR "

I think it must have been an Orange special.


** Yaaawwwnnnnnnnnnnnnnnn ....


Maybe it was the infamous Clockwork Orange ??

Or its nemesis the Clockwork Lemon ???

ROTFL ................


It was in one of their catalogues btw. This is late 60s IIRC.


** So put up or shut up -

YOU RIDICULOUS FUCKING LIAR !!!




..... Phil
 
E

Eeyore

Jan 1, 1970
0
Phil said:
"Eeysore Criminal Nut Case LIAR "


** So put up or shut up -

YOU RIDICULOUS FUCKING LIAR !!!

So if I find the catalogue, scan it and post the page how much are you
going to grovel ? As if of course !

Graham
 
P

Phil Allison

Jan 1, 1970
0
"Eeysore Criminal Nut Case LIAR "
So if I find the catalogue, scan it and post the page how much are you
going to grovel ?



** Nothing to " grovel " about exists.

YOU have not got ANY proof of your fairy tale assertions.

Till you have -

SHUT THE **** UP.




.... Phil
 
J

JosephKK

Jan 1, 1970
0
RCA's germanium predecessor to the 2N3055 was arguably the 2N2147. If
memory serves, PD = 25 watts, FT = 3 MHz. SOA = negligible. Many of the
first generation mass-market *production* hi fi power amps used the 2N2147
with a driver transformer. This included Knight Kit, Heath Kit, Ten Tec,
Altec Lansing, etc. Mainstream mid-fi producers like H. H. Scott, Sherwood,
and Fisher AFAIK never produced any germanium power amps. Their first
generation products were based on 2N3055 and similar devices.


AFAIK the first generation data sheets characterized it as both a power
supply, servo amp, and audio power amp device.


AFAIK the 40411 was introduced several years after the introduction of the
2N3055. I think that there were at least two years of the RCA solid state
book with the 2N305x family in them, before the 404xx family was added.

I had a business partner who, in an earlier venture manufactured SS power
amps for professional use. He based his top-of-the-line products on the
40411. There was also an even more robust device called the 411. Again, my
memory of this is hazy as this was in the late 60s.

According to him, he discovered that the 404xx series of devices were mostly
sold for automotive uses, such as SS ignition modules. For a while RCA was
making these parts literally by the millions. Product consistency was a
problem, which they were very effective at exploiting. The
middle-of-the-road parts went to the car companies under proprietary part
numbers.

The really nice parts, the cream of the crop, were skimmed off sold in
relatively small volumes as 40411s, mostly for audio. Eventually the car
market for 40411-type devices dried up. As the milk dried up, so did the
cream.

According to my friend, RCA tried various ruses to come up with enough
40411-type devices, but could never equal their original product. He sold a
ton of amps that were not durable and was forced out of business.
Eventually, he started cutting open devices, both old and new, and found
results similar to what we've seen far more recently with counterfeit
transistors.. It was his opinion that RCA was sort of counterfeiting their
own product.

This all happened number of decades ago, and should not be taken as a
reflection on the current RCA corp which has been bought and sold at least
once since then, and is thus under a different management.

I have an old quadraphonic adapter made by a mid-fi or low range high
futility mfgr with germanium outputs, totem pole. I doubt i can find
it in less than a year. Some funky RCA part numbers.
 
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