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Substitution for germanium transistor
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Bob Engelhardt
Jan 5, 2017, 11:03:03 AM1/5/17
to
I have a Heathkit IP-27 bench supply that I got at the dump. Its
problem is that the current limiter doesn't work due to a bad
transistor. Unfortunately, the transistor is a germanium one and
replacements are $30!
I found a forum post where the guy had substituted a silicon transistor
(TIP32C) and he said a germanium diode in the base circuit should also
be replaced with a silicon one. My question is: why does the diode need
to be replaced?
Here is the relevant part of the circuit diagram (transistor Q1 & diode D7):
http://imgur.com/a/43wmd
Thanks,
Bob
problem is that the current limiter doesn't work due to a bad
transistor. Unfortunately, the transistor is a germanium one and
replacements are $30!
I found a forum post where the guy had substituted a silicon transistor
(TIP32C) and he said a germanium diode in the base circuit should also
be replaced with a silicon one. My question is: why does the diode need
to be replaced?
Here is the relevant part of the circuit diagram (transistor Q1 & diode D7):
http://imgur.com/a/43wmd
Thanks,
Bob
dansabr...@yahoo.com
Jan 5, 2017, 11:14:31 AM1/5/17
to
If the transistor you need is a DTG600, NTE179 is a substitute and is germanium. I have one in stock if you want it. This is a TO-3 style transistor right?
The posted schematic was a bit fuzy, so if I have the part number wrong, please post the correct one.
Dan
The posted schematic was a bit fuzy, so if I have the part number wrong, please post the correct one.
Dan
amdx
Jan 5, 2017, 11:38:55 AM1/5/17
to
On 1/5/2017 10:02 AM, Bob Engelhardt wrote:
> I have a Heathkit IP-27 bench supply that I got at the dump. Its
> problem is that the current limiter doesn't work due to a bad
> transistor. Unfortunately, the transistor is a germanium one and
> replacements are $30!
>
> I found a forum post where the guy had substituted a silicon transistor
> (TIP32C) and he said a germanium diode in the base circuit should also
> be replaced with a silicon one.
>My question is: why does the diode need
> to be replaced?
Because the current limiting is partially determined by the
> I have a Heathkit IP-27 bench supply that I got at the dump. Its
> problem is that the current limiter doesn't work due to a bad
> transistor. Unfortunately, the transistor is a germanium one and
> replacements are $30!
>
> I found a forum post where the guy had substituted a silicon transistor
> (TIP32C) and he said a germanium diode in the base circuit should also
> be replaced with a silicon one.
>My question is: why does the diode need
> to be replaced?
relationship between the voltage drops of the diode (0.3V) and the
emitter / base junction of the transistor.
If you change only the transistor to (0.6V) you will probably never
develop enough voltage on the transistor to start it conducting.
Mikek
>
> Here is the relevant part of the circuit diagram (transistor Q1 & diode
> D7):
> http://imgur.com/a/43wmd
>
> Thanks,
> Bob
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Ralph Mowery
Jan 5, 2017, 11:45:35 AM1/5/17
to
In article <o4lql...@news3.newsguy.com>, BobEng...@comcast.net
says...
Without looking, I would say the diode is a form of temperature
compensation and the material of the 2 devices should be the same.
That would be true if they are mounted on the same heat sink.
says...
compensation and the material of the 2 devices should be the same.
That would be true if they are mounted on the same heat sink.
Bob Engelhardt
Jan 5, 2017, 11:59:13 AM1/5/17
to
On 1/5/2017 11:38 AM, amdx wrote:
...
...
>> My question is: why does the diode need
>> to be replaced?
>
> Because the current limiting is partially determined by the
> relationship between the voltage drops of the diode (0.3V) and the
> emitter / base junction of the transistor.
> If you change only the transistor to (0.6V) you will probably never
> develop enough voltage on the transistor to start it conducting.
>
> Mikek
Ah! That makes perfect sense. Thank you.
>> to be replaced?
>
> Because the current limiting is partially determined by the
> relationship between the voltage drops of the diode (0.3V) and the
> emitter / base junction of the transistor.
> If you change only the transistor to (0.6V) you will probably never
> develop enough voltage on the transistor to start it conducting.
>
> Mikek
Bob Engelhardt
Jan 5, 2017, 12:08:15 PM1/5/17
to
On 1/5/2017 11:14 AM, dansabr...@yahoo.com wrote:
> If the transistor you need is a DTG600, NTE179 is a substitute and is germanium. I have one in stock if you want it. This is a TO-3 style transistor right?
>
> The posted schematic was a bit fuzy, so if I have the part number wrong, please post the correct one.
The transistor is a DLG600. I remember seeing that the NTE179 was a
> If the transistor you need is a DTG600, NTE179 is a substitute and is germanium. I have one in stock if you want it. This is a TO-3 style transistor right?
>
> The posted schematic was a bit fuzy, so if I have the part number wrong, please post the correct one.
substitute, but the NTE179's that I found were just about as expensive.
Especially compared to the $0.48 for the TIP32C.
Thanks just the same.
Bob
Bob Engelhardt
Jan 5, 2017, 12:46:15 PM1/5/17
to
On 1/5/2017 12:07 PM, Bob Engelhardt wrote:
> The transistor is a DLG600. ...
Oops - D _T_ G, as you said
> The transistor is a DLG600. ...
Oops - D _T_ G, as you said
Jeff Liebermann
Jan 5, 2017, 1:05:01 PM1/5/17
to
<http://www.ebay.com/sch/i.html?_nkw=nte179>
Yep, expensive.
DLG600 is rated at 90V/25A, while the TIP32C at 100V/3A. That would
seem to be a rather poor choice for a substitute.
If you substitute silicon, you'll need to change some component values
to deal with the Vbe change from 0.3v to 0.6v. Probably doubling the
resistance of the 8.2 ohm sense resistor, and changing D7 from
germanium to silicon. Hopefully, the current ranges will remain the
same. The silicon device will have a better gain-bandwidth product,
so a few ferrite beads to keep the power xsistor from oscillating. If
you choose to use a different package, you'll need to do some creative
mounting and heat sinking. The analog series current limiting
transistor will dissipate considerable heat at high loads.
Sounds like too much work. I'll see if can find one in my junk pile.
I've been hoarding germanium devices for years for use in repairs.
--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
Benderthe.evilrobot
Jan 5, 2017, 2:38:56 PM1/5/17
to
"Bob Engelhardt" <BobEng...@comcast.net> wrote in message
news:o4m0p...@news3.newsguy.com...
> On 1/5/2017 12:07 PM, Bob Engelhardt wrote:
>> The transistor is a DLG600. ...
>
> Oops - D _T_ G, as you said
TBH: I'd strip out the original current limiter circuit and rebuild with one
>> The transistor is a DLG600. ...
>
> Oops - D _T_ G, as you said
from a more modern linear PSU.
Its usual practice to use a separate small signal transistor who's B/E
threshold detects the volt drop across the current sense resistor. Its
collector shunts away base current from the pass transistor. If you go that
far - a Darlington pass transistor has a number of advantages.
The B/E threshold is different between silicon and germanium, so you need to
re calculate the current sense resistors. There's various online archives of
test gear schematics - you can probably find a circuit that you can pretty
much copy.
Benderthe.evilrobot
Jan 5, 2017, 2:44:02 PM1/5/17
to
"Ralph Mowery" <rmower...@earthlink.net> wrote in message
news:MPG.32d8422c...@news.east.earthlink.net...
diode Vf is pretty much a reference voltage generator that the sense
resistor volt drop is compared to - the fact that the diode also provides
dome degree of temp-comp, is probably incidental.
Bob Engelhardt
Jan 5, 2017, 3:57:08 PM1/5/17
to
On 1/5/2017 2:39 PM, Benderthe.evilrobot wrote:
> TBH: I'd strip out the original current limiter circuit and rebuild with
> one from a more modern linear PSU. ...
> TBH: I'd strip out the original current limiter circuit and rebuild with
Too much. I could even live without the limiter, but for a couple of
cheap parts, I'll fix it. But not anything more.
Bob Engelhardt
Jan 5, 2017, 4:04:33 PM1/5/17
to
On 1/5/2017 1:04 PM, Jeff Liebermann wrote:
...
>
> If you substitute silicon, you'll need to change some component values
> to deal with the Vbe change from 0.3v to 0.6v. Probably doubling the
> resistance of the 8.2 ohm sense resistor, and changing D7 from
> germanium to silicon. Hopefully, the current ranges will remain the
> same. The silicon device will have a better gain-bandwidth product,
> so a few ferrite beads to keep the power xsistor from oscillating. If
> you choose to use a different package, you'll need to do some creative
> mounting and heat sinking. The analog series current limiting
> transistor will dissipate considerable heat at high loads.
There is no calibration in the circuit - the current limit is picked by
rotating a pot until the current is limited where you want it.
Hopefully this will be able to account for the different device. There
was a poster who did this, so I'm probably OK.
I will mount it, isolated, to the steel frame. And at 1.5A that
"should" be enough sinking.
> Sounds like too much work. I'll see if can find one in my junk pile.
> I've been hoarding germanium devices for years for use in repairs.
>
My order is in, but thanks anyhow.
Bob
...
> DLG600 is rated at 90V/25A, while the TIP32C at 100V/3A. That would
> seem to be a rather poor choice for a substitute.
What you don't know, cause I didn't say, is that the supply is 50v, 1.5A.
> seem to be a rather poor choice for a substitute.
>
> If you substitute silicon, you'll need to change some component values
> to deal with the Vbe change from 0.3v to 0.6v. Probably doubling the
> resistance of the 8.2 ohm sense resistor, and changing D7 from
> germanium to silicon. Hopefully, the current ranges will remain the
> same. The silicon device will have a better gain-bandwidth product,
> so a few ferrite beads to keep the power xsistor from oscillating. If
> you choose to use a different package, you'll need to do some creative
> mounting and heat sinking. The analog series current limiting
> transistor will dissipate considerable heat at high loads.
rotating a pot until the current is limited where you want it.
Hopefully this will be able to account for the different device. There
was a poster who did this, so I'm probably OK.
I will mount it, isolated, to the steel frame. And at 1.5A that
"should" be enough sinking.
> Sounds like too much work. I'll see if can find one in my junk pile.
> I've been hoarding germanium devices for years for use in repairs.
>
Bob
Bob Engelhardt
Jan 5, 2017, 4:05:36 PM1/5/17
to
On 1/5/2017 2:44 PM, Benderthe.evilrobot wrote:
>...- the fact that the diode also
>...- the fact that the diode also
> provides dome degree of temp-comp, is probably incidental.
Yeah - the diode and transistor are very thermally independent.
Benderthe.evilrobot
Jan 5, 2017, 4:44:24 PM1/5/17
to
news:o4mbt...@news3.newsguy.com...
I've knocked a complete current limiter together in an evening - basically
just a scrap of sheet aluminium and a few components that were laying
around.
You could use a Si transistor and fit the matching Si diode, but you'll
probably have to recalculate all the sense resistors - which is most of the
work.
just a scrap of sheet aluminium and a few components that were laying
around.
You could use a Si transistor and fit the matching Si diode, but you'll
probably have to recalculate all the sense resistors - which is most of the
work.
John Robertson
Jan 5, 2017, 5:14:52 PM1/5/17
to
On 2017/01/05 8:38 AM, amdx wrote:
> On 1/5/2017 10:02 AM, Bob Engelhardt wrote:
>> I have a Heathkit IP-27 bench supply that I got at the dump. Its
>> problem is that the current limiter doesn't work due to a bad
>> transistor. Unfortunately, the transistor is a germanium one and
>> replacements are $30!
>>
>> I found a forum post where the guy had substituted a silicon transistor
>> (TIP32C) and he said a germanium diode in the base circuit should also
>> be replaced with a silicon one.
>
>
>> My question is: why does the diode need
>> to be replaced?
>
> Because the current limiting is partially determined by the
> relationship between the voltage drops of the diode (0.3V) and the
> emitter / base junction of the transistor.
> If you change only the transistor to (0.6V) you will probably never
> develop enough voltage on the transistor to start it conducting.
>
> Mikek
>
Mikek, would replacing the germanium diode with a silicon one fix the
> On 1/5/2017 10:02 AM, Bob Engelhardt wrote:
>> I have a Heathkit IP-27 bench supply that I got at the dump. Its
>> problem is that the current limiter doesn't work due to a bad
>> transistor. Unfortunately, the transistor is a germanium one and
>> replacements are $30!
>>
>> I found a forum post where the guy had substituted a silicon transistor
>> (TIP32C) and he said a germanium diode in the base circuit should also
>> be replaced with a silicon one.
>
>
>> My question is: why does the diode need
>> to be replaced?
>
> Because the current limiting is partially determined by the
> relationship between the voltage drops of the diode (0.3V) and the
> emitter / base junction of the transistor.
> If you change only the transistor to (0.6V) you will probably never
> develop enough voltage on the transistor to start it conducting.
>
> Mikek
>
voltage drop you speak of?
John :-#)#
>
>>
>> Here is the relevant part of the circuit diagram (transistor Q1 & diode
>> D7):
>> http://imgur.com/a/43wmd
>>
>> Thanks,
>> Bob
>
>
--
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
(604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."
amdx
Jan 5, 2017, 7:32:00 PM1/5/17
to
On 1/5/2017 4:14 PM, John Robertson wrote:
> On 2017/01/05 8:38 AM, amdx wrote:
>> On 1/5/2017 10:02 AM, Bob Engelhardt wrote:
>>> I have a Heathkit IP-27 bench supply that I got at the dump. Its
>>> problem is that the current limiter doesn't work due to a bad
>>> transistor. Unfortunately, the transistor is a germanium one and
>>> replacements are $30!
>>>
>>> I found a forum post where the guy had substituted a silicon transistor
>>> (TIP32C) and he said a germanium diode in the base circuit should also
>>> be replaced with a silicon one.
>>
>>
>>> My question is: why does the diode need
>>> to be replaced?
>>
>> Because the current limiting is partially determined by the
>> relationship between the voltage drops of the diode (0.3V) and the
>> emitter / base junction of the transistor.
>> If you change only the transistor to (0.6V) you will probably never
>> develop enough voltage on the transistor to start it conducting.
>>
>> Mikek
>>
>
> Mikek, would replacing the germanium diode with a silicon one fix the
> voltage drop you speak of?
>
> John :-#)#
>
There are twenty regulars here that could give you all the details
> On 2017/01/05 8:38 AM, amdx wrote:
>> On 1/5/2017 10:02 AM, Bob Engelhardt wrote:
>>> I have a Heathkit IP-27 bench supply that I got at the dump. Its
>>> problem is that the current limiter doesn't work due to a bad
>>> transistor. Unfortunately, the transistor is a germanium one and
>>> replacements are $30!
>>>
>>> I found a forum post where the guy had substituted a silicon transistor
>>> (TIP32C) and he said a germanium diode in the base circuit should also
>>> be replaced with a silicon one.
>>
>>
>>> My question is: why does the diode need
>>> to be replaced?
>>
>> Because the current limiting is partially determined by the
>> relationship between the voltage drops of the diode (0.3V) and the
>> emitter / base junction of the transistor.
>> If you change only the transistor to (0.6V) you will probably never
>> develop enough voltage on the transistor to start it conducting.
>>
>> Mikek
>>
>
> Mikek, would replacing the germanium diode with a silicon one fix the
> voltage drop you speak of?
>
> John :-#)#
>
with the math, I'm not one of them.
If it were me, I'd change both diode and transistor to silicon and see
how it works. I think it will.
Mikek
>>
>>>
>>> Here is the relevant part of the circuit diagram (transistor Q1 & diode
>>> D7):
>>> http://imgur.com/a/43wmd
>>>
>>> Thanks,
>>> Bob
>>
>>
>
Benderthe.evilrobot
Jan 6, 2017, 3:01:15 PM1/6/17
to
"amdx" <noj...@knology.net> wrote in message
news:o4mof1$oq3$1...@dont-email.me...
kept in step with the Vbe of the new transistor.
The silicon transistor still needs more Vbe to get it conducting, so I
suspect the sense resistors will also need some adjustment.
olds...@tubes.com
Jan 29, 2017, 4:03:17 PM1/29/17
to
On Thu, 05 Jan 2017 10:04:58 -0800, Jeff Liebermann <je...@cruzio.com>
wrote:
I have not heard about germanium in years. When I played around with old
tube stuff in the 60s - 70s, I remember germanium diodes were fairly
common. I never ran across a germanium transistor.
Reading this thread made me question what germanium really is, and I
read the following article (good article). I know it was used to make
the FIRST semiconductors, I never knew much more about it.
It appears it's a costly elemental material.
Here are a few clips from that article.
[Quote]
From:
https://en.wikipedia.org/wiki/Germanium
Germanium "metal" (isolated germanium) is used as a semiconductor in
transistors and various other electronic devices. Historically, the
first decade of semiconductor electronics was based entirely on
germanium. Today, the amount of germanium produced for semiconductor
electronics is one fiftieth the amount of ultra-high purity silicon
produced for the same. Presently, the major end uses are fibre-optic
systems, infrared optics, solar cell applications, and light-emitting
diodes (LEDs). Germanium compounds are also used for polymerization
catalysts and have most recently found use in the production of
nanowires. This element forms a large number of organometallic
compounds, such as tetraethylgermane, useful in organometallic
chemistry.
-
Germanium differs from silicon in that the supply is limited by the
availability of exploitable sources, while the supply of silicon is
limited only by production capacity since silicon comes from ordinary
sand and quartz. While silicon could be bought in 1998 for less than $10
per kg, the price of germanium was almost $800 per kg.
[End Quote]
wrote:
tube stuff in the 60s - 70s, I remember germanium diodes were fairly
common. I never ran across a germanium transistor.
Reading this thread made me question what germanium really is, and I
read the following article (good article). I know it was used to make
the FIRST semiconductors, I never knew much more about it.
It appears it's a costly elemental material.
Here are a few clips from that article.
[Quote]
From:
https://en.wikipedia.org/wiki/Germanium
Germanium "metal" (isolated germanium) is used as a semiconductor in
transistors and various other electronic devices. Historically, the
first decade of semiconductor electronics was based entirely on
germanium. Today, the amount of germanium produced for semiconductor
electronics is one fiftieth the amount of ultra-high purity silicon
produced for the same. Presently, the major end uses are fibre-optic
systems, infrared optics, solar cell applications, and light-emitting
diodes (LEDs). Germanium compounds are also used for polymerization
catalysts and have most recently found use in the production of
nanowires. This element forms a large number of organometallic
compounds, such as tetraethylgermane, useful in organometallic
chemistry.
-
Germanium differs from silicon in that the supply is limited by the
availability of exploitable sources, while the supply of silicon is
limited only by production capacity since silicon comes from ordinary
sand and quartz. While silicon could be bought in 1998 for less than $10
per kg, the price of germanium was almost $800 per kg.
[End Quote]
Benderthe.evilrobot
Jan 29, 2017, 4:31:46 PM1/29/17
to
<olds...@tubes.com> wrote in message
news:2gls8c9v6rniulp4e...@4ax.com...
used.
Not difficult to see how it might be hard to come by nowadays.
Jeff Liebermann
Jan 29, 2017, 5:10:17 PM1/29/17
to
On Sun, 29 Jan 2017 15:01:02 -0600, olds...@tubes.com wrote:
>I have not heard about germanium in years. When I played around with old
>tube stuff in the 60s - 70s, I remember germanium diodes were fairly
>common. I never ran across a germanium transistor.
Germanium transistors were very common in the 1960's. For example, I
>I have not heard about germanium in years. When I played around with old
>tube stuff in the 60s - 70s, I remember germanium diodes were fairly
>common. I never ran across a germanium transistor.
was selling all germanium Motorola pagers and partly germanium mobile
radios at the time. All of the old vibrator power supply to
transistor conversions used germanium power transistors. Most of the
AM car radios were germanium.
Germanium is not dead today. There are SiGe devices that use the best
properties of both materials to good advantage.
<https://en.wikipedia.org/wiki/Silicon-germanium>
Germanium is also the preferred material for Infrared lenses.
<http://www.iiviinfrared.com/Optical-Materials/ge.html>
>While silicon could be bought in 1998 for less than $10
>per kg, the price of germanium was almost $800 per kg.
($800/lb):
<https://minerals.usgs.gov/minerals/pubs/commodity/germanium/mcs-2016-germa.pdf>
MJC
Jan 29, 2017, 5:31:57 PM1/29/17
to
In article <3btjA.131757$MU7....@fx18.am4>,
Benderthe...@virginmedia.com says...
project to build a quartz clock. I think every transistor was germanium.
To divide the crystal frequency by multiple decades it used locked
multivibrators (no digital circuits whatsoever, though my employer made
computers). Anyone seen a circuit like this: https://onedrive.live.com/?
cid=72C9DE495D23AD02&id=72C9DE495D23AD02%215482&parId=72C9DE495D23AD02%
215481&o=OneUp ?
It was my very own design; I still have the circuit value calculations!
Mike.
Benderthe...@virginmedia.com says...
> > I have not heard about germanium in years. When I played around with
old
> > tube stuff in the 60s - 70s, I remember germanium diodes were fairly
> > common. I never ran across a germanium transistor.
> >
> > Reading this thread made me question what germanium really is, and I
> > read the following article (good article). I know it was used to make
> > the FIRST semiconductors, I never knew much more about it.
> > It appears it's a costly elemental material.
Back in the early 1960s I conducted an undergraduate/apprentice training
old
> > tube stuff in the 60s - 70s, I remember germanium diodes were fairly
> > common. I never ran across a germanium transistor.
> >
> > Reading this thread made me question what germanium really is, and I
> > read the following article (good article). I know it was used to make
> > the FIRST semiconductors, I never knew much more about it.
> > It appears it's a costly elemental material.
project to build a quartz clock. I think every transistor was germanium.
To divide the crystal frequency by multiple decades it used locked
multivibrators (no digital circuits whatsoever, though my employer made
computers). Anyone seen a circuit like this: https://onedrive.live.com/?
cid=72C9DE495D23AD02&id=72C9DE495D23AD02%215482&parId=72C9DE495D23AD02%
215481&o=OneUp ?
It was my very own design; I still have the circuit value calculations!
Mike.
jurb...@gmail.com
Jan 30, 2017, 4:46:11 AM1/30/17
to
Would have liked to see that but onedrive doesn't seem to like my computer. I am sure some sort of download will fix everything but they can stick that where it is sure not to get a sunburn.
MJC
Jan 30, 2017, 6:21:36 AM1/30/17
to
In article <067ebd37-fe5a-475d...@googlegroups.com>,
jurb...@gmail.com says...
URL link. Please try this instead:
<https://goo.gl/photos/cZRDRY1JB3vTTr2F9>
Mike.
jurb...@gmail.com says...
>
> Would have liked to see that but onedrive doesn't seem to like my computer. I am sure some sort of download will fix everything but they can stick that where it is sure not to get a sunburn.
Thanks for that; I'm not good at "sharing"! It should just have been a
> Would have liked to see that but onedrive doesn't seem to like my computer. I am sure some sort of download will fix everything but they can stick that where it is sure not to get a sunburn.
URL link. Please try this instead:
<https://goo.gl/photos/cZRDRY1JB3vTTr2F9>
Mike.
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