BC 109 improvement?
 

Have a circuit from the '70s I wish to try and it uses BC 109/179
complimentary pairs. Is there a better choice these days that is a direct
substitute?

--
*If at first you don't succeed, redefine success.

Dave Plowman London SW
To e-mail, change noise into sound.

BC 109 improvement?
 

"Dave Plowman (News)" wrote in message
...
Have a circuit from the '70s I wish to try and it uses BC
109/179
complimentary pairs. Is there a better choice these days that
is a direct
substitute?

--
*If at first you don't succeed, redefine success.

Dave Plowman London SW
To e-mail, change noise into sound.



BC549

BC 109 improvement?
 

On Mon, 06 Aug 2012 19:12:21 +0100, "Dave Plowman (News)"
wrote:

Have a circuit from the '70s I wish to try and it uses BC 109/179
complimentary pairs. Is there a better choice these days that is a direct
substitute?

These days, probably the 2N2222 and the 2N2907 would do the trick.
The BC109 was a strange transistor - touted as low noise, but it was
anything but.

Is there a schematic? Could offer better advice with a look at that.

d

BC 109 improvement?
 

"Dave Plowman (News)"

Have a circuit from the '70s I wish to try and it uses BC 109/179
complimentary pairs. Is there a better choice these days that is a direct
substitute?


** Nope.

BC109s and BC179s make excellent compliments for pre-amp circuits PLUS the
metal pack makes for ultra long life.

And certainly do NOT try Don's barking mad idea of using switching
transistors.



.... Phil

BC 109 improvement?
 

On Mon, 06 Aug 2012 20:04:00 GMT, (Don Pearce) wrote:

On Mon, 06 Aug 2012 19:12:21 +0100, "Dave Plowman (News)"
wrote:

Have a circuit from the '70s I wish to try and it uses BC 109/179
complimentary pairs. Is there a better choice these days that is a direct
substitute?

These days, probably the 2N2222 and the 2N2907 would do the trick.
The BC109 was a strange transistor - touted as low noise, but it was
anything but.

Is there a schematic? Could offer better advice with a look at that.

d

You can safely ignore the stuff from downunder. Switching transistors
are just as linear as any other kind. What makes them good for
switching is that when you turn them on fully they drop less voltage
across the collector and emitter.

If you are looking for ultimate low noise, consider connecting a
couple of transistors in parallel in each location. Double up on the
current so they are each still biased as before.

d

BC 109 improvement?
 

"Don Pearce = 100% Demented "
"Dave Plowman (News)"

Have a circuit from the '70s I wish to try and it uses BC 109/179
complimentary pairs. Is there a better choice these days that is a direct
substitute?

These days, probably the 2N2222 and the 2N2907 would do the trick.
The BC109 was a strange transistor - touted as low noise, but it was
anything but.


** Utter bull****.


You can safely ignore the stuff from downunder.

** The **** that drops out of you for example.


Switching transistors
are just as linear as any other kind.

** ******** they are.


If you are looking for ultimate low noise,


** The OP has not said he was making a low Z mic pre-amp.

For almost any other audio app, BC109s et alia are fine.



..... Phil

BC 109 improvement?
 

In article , Dave Plowman (News)
wrote:
Have a circuit from the '70s I wish to try and it uses BC 109/179
complimentary pairs. Is there a better choice these days that is a
direct substitute?

My initial reaction was that 'better' implies NOT a 'direct substitute'.
Having something 'different' AND 'the same' is a bit of a challenge... :-)

To clarify that I think you'd need to say more about what 'better' would
mean, or provide circuit details.

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

BC 109 improvement?
 

On 8/7/2012 4:12 AM, Dave Plowman (News) wrote:
Have a circuit from the '70s I wish to try and it uses BC 109/179
complimentary pairs. Is there a better choice these days that is a direct
substitute?


As PA suggested, the BC109 came in a hermetically sealed metal can. That
made it superior to almost any plastic pack device. That said, modern
plastic transistors are pretty decent. Depending on the Voltage, current
and hFE requirements, you could use:

2N5087/2N5210 (ancient, but still excellent devices).

There are many others as well.


--
Trevor Wilson www.rageaudio.com.au

BC 109 improvement?
 

In article , Trevor Wilson trevor@SPAM
BLOCKrageaudio.com.au scribeth thus
On 8/7/2012 4:12 AM, Dave Plowman (News) wrote:
Have a circuit from the '70s I wish to try and it uses BC 109/179
complimentary pairs. Is there a better choice these days that is a direct
substitute?


As PA suggested, the BC109 came in a hermetically sealed metal can. That
made it superior to almost any plastic pack device.

Any reason why that should be Trevor?..

Or did you mean at the time the BC 109 came onto the market?..


That said, modern
plastic transistors are pretty decent. Depending on the Voltage, current
and hFE requirements, you could use:

2N5087/2N5210 (ancient, but still excellent devices).

There are many others as well.



--
Tony Sayer

BC 109 improvement?
 

On Thu, 9 Aug 2012 21:53:35 +0100, tony sayer
wrote:


As PA suggested, the BC109 came in a hermetically sealed metal can. That
made it superior to almost any plastic pack device.

Any reason why that should be Trevor?..

Or did you mean at the time the BC 109 came onto the market?..

The hermetic can became superfluous with the advent of passivation.

d

BC 109 improvement?
 

On 8/10/2012 6:53 AM, tony sayer wrote:
In article , Trevor Wilson trevor@SPAM
BLOCKrageaudio.com.au scribeth thus
On 8/7/2012 4:12 AM, Dave Plowman (News) wrote:
Have a circuit from the '70s I wish to try and it uses BC 109/179
complimentary pairs. Is there a better choice these days that is a direct
substitute?


As PA suggested, the BC109 came in a hermetically sealed metal can. That
made it superior to almost any plastic pack device.

Any reason why that should be Trevor?..

Or did you mean at the time the BC 109 came onto the market?..

**Yes and, no. IME, low power, metal can devices demonstrate superior
long term reliability to pre-1980-ish plastic devices. That said, modern
plastic devices appear to provide excellent long term reliability as well.



--
Trevor Wilson www.rageaudio.com.au

BC 109 improvement?
 

"tony sayer"

Or did you mean at the time the BC 109 came onto the market?


** The original BC108 series in TO18 pack preceded plastic equivalents.

The first plastic versions were the BC148 series and BC208 series in SOT25
and TO106 respectively.

The now ubiquitous TO 92 pack came later again.

See:

http://home.hccnet.nl/piet.blaas/gro...bc148b-500.jpg

and

http://www.buy-transistors.com/media...c/bc208b_1.jpg

The TO18 versions, being hermetically sealed, have proved to have longer
service and storage lives.


.... Phil

BC 109 improvement?
 

In article , Trevor Wilson
wrote:


**Yes and, no. IME, low power, metal can devices demonstrate superior
long term reliability to pre-1980-ish plastic devices. That said, modern
plastic devices appear to provide excellent long term reliability as
well.

The key word, though, is 'can' sorry for the pun!. I've known more than
one 'metal can' transistor that were unreliable for various reasons. So as
with types using other packaging it all comes down to how well the
individual devices were made.

In one case Oops, another pun WRT higher power devices I recall a TO3
device that exploded when powered up at low levels and the top hit part of
the wood around the bench so hard that it embossed the maker's name there.
Turned out to be a batch with water vapour inside the can. More common was,
it seems, simply poor contacts so that the device came free of the
metalwork.

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

BC 109 improvement?
 

On 8/10/2012 6:02 PM, Jim Lesurf wrote:
In article , Trevor Wilson
wrote:


**Yes and, no. IME, low power, metal can devices demonstrate superior
long term reliability to pre-1980-ish plastic devices. That said, modern
plastic devices appear to provide excellent long term reliability as
well.

The key word, though, is 'can' sorry for the pun!. I've known more than
one 'metal can' transistor that were unreliable for various reasons. So as
with types using other packaging it all comes down to how well the
individual devices were made.

In one case Oops, another pun WRT higher power devices I recall a TO3
device that exploded when powered up at low levels and the top hit part of
the wood around the bench so hard that it embossed the maker's name there.
Turned out to be a batch with water vapour inside the can. More common was,
it seems, simply poor contacts so that the device came free of the
metalwork.


**Back in the 1970s, I worked on a lot of Marantz products (as the
Australian service manager). Back then, there were a couple of Japanese
suppliers and one US supplier of output devices for Marantz products.
The US supplier was Motorola and their devices were in the, now
infamous, aluminium TO3 cases. The Japs were supplied in (usually)
copper cases, though some may have been steel. The Motorola devices were
far less reliable than the Japanese ones. In fact, often when the
Motorola devices failed, a tiny hole was punctured in the aluminum case,
as part of the innards was expelled outwards. About that time, I read a
white paper published by RCA where it was claimed that their steel TO3
cases could provide more than 1 million hot/cold cycles without failure,
whereas the aluminium cases used by Motorola could only sustain 100,000
hot/cold cycles. Early plastic packs could only manage around 10,000
cycles. Anecdotal evidence and chatting to a couple of people in the
industry seemed to bear this out. I was informed by one person that RCA
used superior wire bonding techniques which assisted with long term
reliability for their devices (they second-sourced Motorola chips in
some cases). As for plastic packs, the only reciever in the Marantz
line-up that used plastic pack output devices enjoyed a 67% failure rate
within the warranty period. That is contrasted by the fabulous 1070
amplifier (that used copper TO3 outputs) which exhibited an impressive
0.5% failure rate within the warranty period. We won't talk about the
mighty Model 500 power amp (I still own mine). Every single one failed,
several times within the warrnty period. Legend has it that the company
spent US$3 million on the design, development, production and warranty
support on the 300 amplifiers produced. Aluminium cased output devices. Yuk.


--
Trevor Wilson www.rageaudio.com.au

BC 109 improvement?
 

"Trevor Wilson"

**Back in the 1970s, I worked on a lot of Marantz products (as the
Australian service manager). Back then, there were a couple of Japanese
suppliers and one US supplier of output devices for Marantz products. The
US supplier was Motorola and their devices were in the, now infamous,
aluminium TO3 cases.

** Infamous ??

That IS putting it a bit strongly !!

FYI:

1. Motorola chips were never bonded direct to Aluminium ( or steel) - but
instead to a small copper alloy slug that sat in a depression in the base of
the Al pack. Solder like material held the chip to the slug and the slug to
the base metal.

( Steel devices have a rather large copper slug that sits on top of the
thin base. )

2. I must have cut a hundred or more TO3 devices open ( mostly Motorola ) to
see the internal construction and identify fakes.


The Japs were supplied in (usually) copper cases, though some may have
been steel. The Motorola devices were far less reliable than the Japanese
ones.

** For some reason other than the one you are crapping on about.


About that time, I read a white paper published by RCA where it was
claimed that their steel TO3 cases could provide more than 1 million
hot/cold cycles without failure, whereas the aluminium cases used by
Motorola could only sustain 100,000 hot/cold cycles.

** I think you have moved the decimal point one place to the right.

HOWEVER a "hot / cold cycle " is one where the chip goes from room temp to
rated max - so would be a rare event in a domestic hi-fi amp.

( Different story for a linear regulated PSU or pro audio amplifiers )

Early plastic packs could only manage around 10,000 cycles. Anecdotal
evidence and chatting to a couple of people in the industry seemed to bear
this out.

** Gossip is very cheap.

And every plastic power device I have ever seen uses a copper heatsinking
base.


..... Phil

BC 109 improvement?
 

"Don Pearce" wrote in message
...

You can safely ignore the stuff from downunder. Switching transistors
are just as linear as any other kind. What makes them good for
switching is that when you turn them on fully they drop less voltage
across the collector and emitter.

My undergraduate engineering circuits class challenge project was for teams
to build as good of a RIAA preamp as could be built with 2N404A transistors.
The prof forgot to limit how many transistors could be used, so I used two
Darlington pairs per gain block, full loop feedback. There was a RIAA preamp
followed by a line level amp with a gain control in-between. It easily
outperformed just about anything commercial in the day for both noise and
distortion. Note that the 2N404A was a dirt cheap switching transistor.

BC 109 improvement?
 

"Trevor Wilson" wrote in message
...

About that time, I read a
white paper published by RCA where it was claimed that their steel TO3
cases could provide more than 1 million hot/cold cycles without failure,
whereas the aluminium cases used by Motorola could only sustain 100,000
hot/cold cycles.

I remember that, too.

RCA made a ton of money making power transistors for early automotive
electronic ignition systems.