When did high-voltage transistors become common?...

[Pimpom]

About 50 years ago, I was asked to make a high voltage constant
current supply for a medical research lab. The requirement was
600V at up to 30mA. I stacked two EL84 tubes in cascode (a 6L6GC
cost more and was less easily available). Television arrived here
in this remote place a decade later and I used TV FB transistors
in an apparatus for a local college.

Looking back on those times, I\'m wondering when high-voltage
power transistors first became common in the more advanced countries.

 

[Phil Allison]

Pimpom wrote:
--------------

About 50 years ago, I was asked to make a high voltage constant
current supply for a medical research lab. The requirement was
600V at up to 30mA. I stacked two EL84 tubes in cascode (a 6L6GC
cost more and was less easily available).

** I have a home brew prototype tube amp module in my workshop using p-p pair of EL84s in low bias class AB. B+ is 650V and screens at 325VDC.

Power out is 60W sine wave, with no sign of red plating.

The TO3 pak BU208 is an early TV flyback type - appeared in or about 1971.

https://www.radiomuseum.org/tubes/tube_bu208.html



...... Phil

 

[piglet]

Early 1970s , there was a short period around 1970 when TV sets were all solid state except for the horizontal drive!

piglet
(Using google groups on a phone while travelling in Africa)

 

[Michael Terrell]

On Friday, August 14, 2020 at 5:23:26 AM UTC-4, piglet wrote:

Early 1970s , there was a short period around 1970 when TV sets were all solid state except for the horizontal drive!

Motorola\'s \'Quasar\' solid state color TVS came out in the late \'60. they only used a vacuum tube for the HV rectifier and the CRT. The audio output transistor was around 125VDC. It used an Allen Bradley carbon comp resistor for a fuse, Anything else wouldn\'t open in time to protect the output transformer.

My dad bought one of these TVs when they first came out. I still have it.

 

[Phil Hobbs]

On 2020-08-14 02:39, Pimpom wrote:

About 50 years ago, I was asked to make a high voltage constant current
supply for a medical research lab. The requirement was 600V at up to
30mA. I stacked two EL84 tubes in cascode (a 6L6GC
cost more and was less easily available). Television arrived here in
this remote place a decade later and I used TV FB transistors in an
apparatus for a local college.

Looking back on those times, I\'m wondering when high-voltage power
transistors first became common in the more advanced countries.

Dunno. I used an 811A in an experimental setup in 1991 though.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[Phil Hobbs]

On 2020-08-14 06:38, Michael Terrell wrote:

On Friday, August 14, 2020 at 5:23:26 AM UTC-4, piglet wrote:
Early 1970s , there was a short period around 1970 when TV sets
were all solid state except for the horizontal drive!


Motorola\'s \'Quasar\' solid state color TVS came out in the late \'60.
they only used a vacuum tube for the HV rectifier and the CRT. The
audio output transistor was around 125VDC. It used an Allen Bradley
carbon comp resistor for a fuse, Anything else wouldn\'t open in time
to protect the output transformer.

My dad bought one of these TVs when they first came out. I still have
it.

That whole \"with its works in a drawer\" thing was apparently an early
example of turning a bug into a feature--those things were notoriously
unreliable.

Cheers

Phil \"grew up watching Admirals\" Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[bitrex]

On 8/14/2020 2:39 AM, Pimpom wrote:

About 50 years ago, I was asked to make a high voltage constant current
supply for a medical research lab. The requirement was 600V at up to
30mA. I stacked two EL84 tubes in cascode (a 6L6GC
cost more and was less easily available). Television arrived here in
this remote place a decade later and I used TV FB transistors in an
apparatus for a local college.

Looking back on those times, I\'m wondering when high-voltage power
transistors first became common in the more advanced countries.

Here\'s a pretty good article:

<http://www.righto.com/2012/02/apple-didnt-revolutionize-power.html#ref65>

The Apple III computer (1980) PSU used a MJ8503 transistor in TO-3
package as the flyback switch, it was rated for 800 volts CE, 150 watts
dissipation, 10 amp pulse current, and 2000 nanosecond rise and fall
times, so switching frequencies into the 10s of khz.

As I understand it that was a state-of-the-art high-voltage power
transistor of the late 1970s.

 

[Tabby]

On Friday, 14 August 2020 at 10:12:23 UTC+1, palli...@gmail.com wrote:

Pimpom wrote:
--------------


About 50 years ago, I was asked to make a high voltage constant
current supply for a medical research lab. The requirement was
600V at up to 30mA. I stacked two EL84 tubes in cascode (a 6L6GC
cost more and was less easily available).

** I have a home brew prototype tube amp module in my workshop using p-p pair of EL84s in low bias class AB. B+ is 650V and screens at 325VDC.

Power out is 60W sine wave, with no sign of red plating.

The TO3 pak BU208 is an early TV flyback type - appeared in or about 1971.

https://www.radiomuseum.org/tubes/tube_bu208.html



..... Phil

BU208 & its relatives became common in TVs in the 70s. Before the 208 TVs normally used 2 transistors stacked or a horizontal output valve. There were other oddballs like SCRs used occasionally but I don\'t remember when.


NT

 

[Pimpom]

On 8/14/2020 2:42 PM, Phil Allison wrote:

Pimpom wrote:
--------------


About 50 years ago, I was asked to make a high voltage constant
current supply for a medical research lab. The requirement was
600V at up to 30mA. I stacked two EL84 tubes in cascode (a 6L6GC
cost more and was less easily available).


** I have a home brew prototype tube amp module in my workshop using p-p pair of EL84s in low bias class AB. B+ is 650V and screens at 325VDC.

Power out is 60W sine wave, with no sign of red plating.

The TO3 pak BU208 is an early TV flyback type - appeared in or about 1971.

https://www.radiomuseum.org/tubes/tube_bu208.html

Television first came to my region when some army people
discovered in 1980 that they could catch a station in
neighbouring Bangladesh. For the first year or so after that,
only B&W Indian sets were available and they all used a BU205
(not BU208). Then smugglers started bringing in Japanese colour
TVs via Burma - National (Panasonic), Sony, Toshiba, JVC,
Sansui........

Repairing TVs took up much of my time during the \'80s and early
90s. It was well nigh impossible to stock all of the variety of
high voltage transistors used by those Japanese models. Luckily,
a BU508 and a few Japanese types from the 2SD and 2SC series
could replace most of them. My own 27-inch Sony from the early
\'80s used an IGBT.

 

[Pimpom]

On 8/14/2020 4:08 PM, Michael Terrell wrote:

On Friday, August 14, 2020 at 5:23:26 AM UTC-4, piglet wrote:
Early 1970s , there was a short period around 1970 when TV sets were all solid state except for the horizontal drive!


Motorola\'s \'Quasar\' solid state color TVS came out in the late \'60. they only used a vacuum tube for the HV rectifier and the CRT. The audio output transistor was around 125VDC. It used an Allen Bradley carbon comp resistor for a fuse, Anything else wouldn\'t open in time to protect the output transformer.

My dad bought one of these TVs when they first came out. I still have it.

I heard that there was a period when car radios used tubes with
12V anode supply in the RF sections and transistors for AF
output. The purpose was to obviate the need for a vibrator to
generate a high voltage plate supply.

 

[piglet]

I doubt IGBT existed early 1980s pretty sure what you’re thinking of was GTO gate turn off thyristor which enjoyed a brief summer as horizontal output driver device, I think mainly one or two mainly European set makers used them.

piglet

 

[Tim Williams]

Within just the last decade, single transistors finally overtook tubes even
in niche circuits -- to be honest, this is probably not so much a
technological leap, as it simply being economical for manufacturers to
target that space.

Example:
IXYS IXTX1R4N450HV
4.5kV 1.4A 960W 40 ohm 88nC

Not that 960W is a realistic figure, as usual, but it\'s probably good for
100W or more with adequate heatsinking (splurging for a nice thick AlN
insulator would be a nice touch, at these voltages).

Compare:
6LW6
7kV 1.4Apk? 40W 40pF

Little data on this particular tube, but we can assume it saturates
somewhere around 50-100V at that 1.4A peak, and maybe is capable of 2A or
more (at somewhat higher voltage drop). So, comparable on-resistance.
Likewise, safe to assume around 150V grid drive is needed to switch it,
giving a grid charge somewhere around 10nC (which, at the 15 times higher
voltage swing, is 1.7 times more grid power).

The MOSFET may not perform very well, as MOSFETs go; the long channel has a
long transit time. Though it seems to be limited by internal R_G more than
that (t_r = 60ns is the published figure).

The tube can go about as fast as you can push it, which is pretty
challenging for so much swing (especially if you only have more tubes to
generate that swing), but also suffers from stray inductance through its
poorly connected octal socket, and tall body. (Contemporary Compactrons
usually made two connections to each grid.)

Anyway, the transistor handily outperforms the tube in most absolute
measures... not to mention size and not needing 18W of heater power.


Supposedly there are single MOSFETs and IGBTs out there, rated for upwards
of 10kV, using SiC. Haven\'t seen anything near that from the usual
suppliers; they may be special order, or restricted (a few would make a
lovely near-field EMP generator). Have seen papers discussing their use on
distribution lines (so, ~4.8kV AC, direct connection -- no transformer
required), for grid and maritime purposes.

Tim

--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Design
Website: https://www.seventransistorlabs.com/

\"Pimpom\" <nobody@nowhere.com> wrote in message
news:KkqZG.70924$rc6.15448@fx06.ams1...

About 50 years ago, I was asked to make a high voltage constant current
supply for a medical research lab. The requirement was 600V at up to 30mA.
I stacked two EL84 tubes in cascode (a 6L6GC
cost more and was less easily available). Television arrived here in this
remote place a decade later and I used TV FB transistors in an apparatus
for a local college.

Looking back on those times, I\'m wondering when high-voltage power
transistors first became common in the more advanced countries.

 

[Pimpom]

On 8/15/2020 12:43 AM, piglet wrote:

I doubt IGBT existed early 1980s pretty sure what you’re thinking of was GTO gate turn off thyristor which enjoyed a brief summer as horizontal output driver device, I think mainly one or two mainly European set makers used them.

piglet

Ah, old age. I checked the schematic and the H-out device is a
common 2SD725 BJT. The IGBT (or whatever it is) is the pincushion
output device. The type number is SG264 but the symbol is
obscured by one of several huge characters from an unknown
language. A search for the datasheet turns up only unrelated devices.

The TV was apparently a high-end, state-of-the-art model with all
kinds of inputs and outputs and connector types. It used a huge
number of ICs and discrete parts.

 

[piglet]

That could be a fet. I have seen pincushion correction done with a medium power MOSFETs and they were just beginning to appear in consumer gear early 1980s.

piglet

 

[legg]

On Fri, 14 Aug 2020 12:09:34 +0530, Pimpom <nobody@nowhere.com> wrote:

About 50 years ago, I was asked to make a high voltage constant
current supply for a medical research lab. The requirement was
600V at up to 30mA. I stacked two EL84 tubes in cascode (a 6L6GC
cost more and was less easily available). Television arrived here
in this remote place a decade later and I used TV FB transistors
in an apparatus for a local college.

Looking back on those times, I\'m wondering when high-voltage
power transistors first became common in the more advanced countries.

Westinghouse were doing 300V in TO82 in 1962 2N1015/6(F)
350V in TO49 in 1962 2N1829/36
350V in TO83 in 1963 2N2129/30

Delco (GM) were doing 300V in TO36 in 1963 2N3079/80
400V in TO3 in 1965. DTS-4xx
500V/600V in TO36 in 1966 2N2582/3/4/5
700Vcex in TO3 in 1968 2N3902

TI(UK)/Sescosem 750V in TO3 in 1968 BU105
550V in TO3 in 1969 BU112

I don\'t expect any were common before 1970. Darlingtons
in 1972.

Lots of articles about safe operating area, and a few about
using series devices in regulators up to 1500V input, after
1972.

RL

 

[server]

On Friday, 14 August 2020 22:59:05 UTC+1, legg wrote:

On Fri, 14 Aug 2020 12:09:34 +0530, Pimpom <nobody@nowhere.com> wrote:

About 50 years ago, I was asked to make a high voltage constant
current supply for a medical research lab. The requirement was
600V at up to 30mA. I stacked two EL84 tubes in cascode (a 6L6GC
cost more and was less easily available). Television arrived here
in this remote place a decade later and I used TV FB transistors
in an apparatus for a local college.

Looking back on those times, I\'m wondering when high-voltage
power transistors first became common in the more advanced countries.


Westinghouse were doing 300V in TO82 in 1962 2N1015/6(F)
350V in TO49 in 1962 2N1829/36
350V in TO83 in 1963 2N2129/30

Delco (GM) were doing 300V in TO36 in 1963 2N3079/80
400V in TO3 in 1965. DTS-4xx
500V/600V in TO36 in 1966 2N2582/3/4/5
700Vcex in TO3 in 1968 2N3902

TI(UK)/Sescosem 750V in TO3 in 1968 BU105
550V in TO3 in 1969 BU112

I don\'t expect any were common before 1970. Darlingtons
in 1972.

Lots of articles about safe operating area, and a few about
using series devices in regulators up to 1500V input, after
1972.

RL

I salvaged BU105s from the scrap pile behind a TV repair shop
in the UK around 1970 or 1971, so they must have been in
production for a while then.

John

 

[Michael Terrell]

On Friday, August 14, 2020 at 8:26:59 AM UTC-4, Phil Hobbs wrote:

On 2020-08-14 06:38, Michael Terrell wrote:
On Friday, August 14, 2020 at 5:23:26 AM UTC-4, piglet wrote:
Early 1970s , there was a short period around 1970 when TV sets
were all solid state except for the horizontal drive!


Motorola\'s \'Quasar\' solid state color TVS came out in the late \'60.
they only used a vacuum tube for the HV rectifier and the CRT. The
audio output transistor was around 125VDC. It used an Allen Bradley
carbon comp resistor for a fuse, Anything else wouldn\'t open in time
to protect the output transformer.

My dad bought one of these TVs when they first came out. I still have
it.


That whole \"with its works in a drawer\" thing was apparently an early
example of turning a bug into a feature--those things were notoriously
unreliable.

It was still working, 40 years later. I last fired it up in 1999 and it still had a good picture, but it was starting to get \'Fish Eye\' where the bonding was separating from the safety glass.

I converted a metal cased 21\" version into my first color monitor in the mid \'80s.

Most problems were caused by idiot techs o handled the connectors and let body oils and sweat on them. This set was hit by lightning twice. It blew out the RF preamp in the VHF tuner, both times. It had one electrolytic fail, during all those years. It had a 23EGP22 CRT. No doubt the worst rectangular color CRT ever built. I replaced it when it was seven years old. It was so gassy that it took over a half hour to get a decent image, if the power had been out. The \'Instant On\' feature wasted some power, but it tripled the useful life of that tube.

I replaced it with a 25\" Black Matrix CRT. Everyone who saw it, insisted that it wasn\'t the same TV.

The biggest idiots soldered the modules to the chassis connectors, making them unrepeatable.

 

[Michael Terrell]

On Friday, August 14, 2020 at 2:38:54 PM UTC-4, Pimpom wrote:

I heard that there was a period when car radios used tubes with
12V anode supply in the RF sections and transistors for AF
output. The purpose was to obviate the need for a vibrator to
generate a high voltage plate supply.

Bendix/ford did that, while GM/Delco had already switched to all transistor designs. One early GM model had a removable radio, that connected to a power amplifier when you slid it into the rest of the dash mounted radio. I think that was a 1959 model? I should still have the manual, somewhere.

 

[John Larkin]

On Fri, 14 Aug 2020 12:09:34 +0530, Pimpom <nobody@nowhere.com> wrote:

About 50 years ago, I was asked to make a high voltage constant
current supply for a medical research lab. The requirement was
600V at up to 30mA. I stacked two EL84 tubes in cascode (a 6L6GC
cost more and was less easily available). Television arrived here
in this remote place a decade later and I used TV FB transistors
in an apparatus for a local college.

Looking back on those times, I\'m wondering when high-voltage
power transistors first became common in the more advanced countries.

I found a really cool use for the c-b junction of a horizontal-output
transistor that accidentally had the ideal doping profile. It\'s not
made any more, of course.

My great little 3KV Bertan 215 bench power supply has one tube inside.
I bought a couple of spares.

 

[legg]

On Fri, 14 Aug 2020 15:35:07 -0700 (PDT), jrwalliker@gmail.com wrote:

On Friday, 14 August 2020 22:59:05 UTC+1, legg wrote:
On Fri, 14 Aug 2020 12:09:34 +0530, Pimpom <nobody@nowhere.com> wrote:

About 50 years ago, I was asked to make a high voltage constant
current supply for a medical research lab. The requirement was
600V at up to 30mA. I stacked two EL84 tubes in cascode (a 6L6GC
cost more and was less easily available). Television arrived here
in this remote place a decade later and I used TV FB transistors
in an apparatus for a local college.

Looking back on those times, I\'m wondering when high-voltage
power transistors first became common in the more advanced countries.


Westinghouse were doing 300V in TO82 in 1962 2N1015/6(F)
350V in TO49 in 1962 2N1829/36
350V in TO83 in 1963 2N2129/30

Delco (GM) were doing 300V in TO36 in 1963 2N3079/80
400V in TO3 in 1965. DTS-4xx
500V/600V in TO36 in 1966 2N2582/3/4/5
700Vcex in TO3 in 1968 2N3902

TI(UK)/Sescosem 750V in TO3 in 1968 BU105
550V in TO3 in 1969 BU112

I don\'t expect any were common before 1970. Darlingtons
in 1972.

Lots of articles about safe operating area, and a few about
using series devices in regulators up to 1500V input, after
1972.

RL

I salvaged BU105s from the scrap pile behind a TV repair shop
in the UK around 1970 or 1971, so they must have been in
production for a while then.

John

I\'m just going by dates on app notes and spec drwgs.
By that date, they will have been in distribution, though
unlikely at commodity pricing, while single-sourced.

RL