BJT switch calculation text...

[jmariano]

Dear All,

I was wondering if someone could direct me to a text or book that explains all the steps needed to calculate the circuit parameters of a BJT used a switch, preferably with real examples using data from the datasheet. I\'ve been using these thing all my live, but now I realize that my design process had to much guess work and trial and error to be serious.

I have searched the web, but all texts I was able to find were too simple, directed to the non initiated hobbyist. I often use \"the art of electronics\", but on this regard, PH doesn\'t goes in to much detail.

Thanks
JM

 

[piglet]

On 08/12/2021 22:46, jmariano wrote:

Dear All,

I was wondering if someone could direct me to a text or book that explains all the steps needed to calculate the circuit parameters of a BJT used a switch, preferably with real examples using data from the datasheet. I\'ve been using these thing all my live, but now I realize that my design process had to much guess work and trial and error to be serious.

I have searched the web, but all texts I was able to find were too simple, directed to the non initiated hobbyist. I often use \"the art of electronics\", but on this regard, PH doesn\'t goes in to much detail.

Thanks
JM

You didn\'t say if this lack is for high power versus low power or at
high speed or static etc. But you might find what you are looking for by
browsing archive manufacturers applications handbooks and databook
compendiums from the mid 1970s thru early 1980s. This is the period when
switch mode power supplies were taking off and before mosfets took over
the switch role. Some had innovative ways of dealing with storage time
and SOA etc and methods to evaluate and select.

piglet

 

[whit3rd]

On Wednesday, December 8, 2021 at 2:46:04 PM UTC-8, jmariano wrote:

> I was wondering if someone could direct me to a text or book that explains all the steps needed to calculate the circuit parameters of a BJT used a switch

That was a hot topic when folk were first using transistors; the basics are in chapter six here

<https://archive.org/embed/GE_-_Transistor_Manual_1964>

 

[Martin Brown]

On 09/12/2021 08:19, piglet wrote:

On 08/12/2021 22:46, jmariano wrote:
Dear All,

I was wondering if someone could direct me to a text or book that
explains all the steps needed to calculate the circuit parameters of a
BJT used a switch, preferably with real examples using data from the
datasheet. I\'ve been using these thing all my live, but now I realize
that my design process had to much guess work and trial and error to
be serious.

I have searched the web, but all texts I was able to find were too
simple, directed to the non initiated hobbyist. I often use \"the art
of electronics\", but on this regard, PH doesn\'t goes in to much detail.

Thanks
JM


You didn\'t say if this lack is for high power versus low power or at
high speed or static etc. But you might find what you are looking for by
browsing archive manufacturers applications handbooks and databook
compendiums from the mid 1970s thru early 1980s. This is the period when
switch mode power supplies were taking off and before mosfets took over
the switch role. Some had innovative ways of dealing with storage time
and SOA etc and methods to evaluate and select.

The application notes for Ferranti e-line transistors (small signal) is
online and quite a nice introduction to BJT design (though dated).

http://www.introni.it/pdf/Ferranti%20-%20E%20Line%20Transistor%20Applications%201974.pdf

Back in the days when some logics was still done in discrete parts.

--
Regards,
Martin Brown

 

[jmariano]

On Thursday, 9 December 2021 at 15:20:06 UTC, Don wrote:

Martin Brown wrote:
piglet wrote:
jmariano wrote:
Dear All,

I was wondering if someone could direct me to a text or book that
explains all the steps needed to calculate the circuit parameters of a
BJT used a switch, preferably with real examples using data from the
datasheet. I\'ve been using these thing all my live, but now I realize
that my design process had to much guess work and trial and error to
be serious.

I have searched the web, but all texts I was able to find were too
simple, directed to the non initiated hobbyist. I often use \"the art
of electronics\", but on this regard, PH doesn\'t goes in to much detail.

Thanks
JM


You didn\'t say if this lack is for high power versus low power or at
high speed or static etc. But you might find what you are looking for by
browsing archive manufacturers applications handbooks and databook
compendiums from the mid 1970s thru early 1980s. This is the period when
switch mode power supplies were taking off and before mosfets took over
the switch role. Some had innovative ways of dealing with storage time
and SOA etc and methods to evaluate and select.

The application notes for Ferranti e-line transistors (small signal) is
online and quite a nice introduction to BJT design (though dated).

http://www.introni.it/pdf/Ferranti%20-%20E%20Line%20Transistor%20Applications%201974.pdf

Back in the days when some logics was still done in discrete parts.
For a more theoretical take, this excerpt adapts the small-signal
hybrid-π model to large-signal switching:

https://crcomp.net/smps/bjt.pdf

Danke,

--
Don, KB7RPU, https://www.qsl.net/kb7rpu
There was a young lady named Bright Whose speed was far faster than light;
She set out one day In a relative way And returned on the previous night.

Thank you very much for the references.
Amazing!
These are very useful and hard to find, unless you know exactly what
to look for and here.
I was actually thinking of a much simpler use, like driving a LED or a
solenoid, but I guess I will find what I\'m looking for in one of these
texts.
What a shame these things are not teached at the university.
Cheers
JM

 

[bitrex]

On 12/9/21 1:51 PM, jmariano wrote:

On Thursday, 9 December 2021 at 15:20:06 UTC, Don wrote:
Martin Brown wrote:
piglet wrote:
jmariano wrote:
Dear All,

I was wondering if someone could direct me to a text or book that
explains all the steps needed to calculate the circuit parameters of a
BJT used a switch, preferably with real examples using data from the
datasheet. I\'ve been using these thing all my live, but now I realize
that my design process had to much guess work and trial and error to
be serious.

I have searched the web, but all texts I was able to find were too
simple, directed to the non initiated hobbyist. I often use \"the art
of electronics\", but on this regard, PH doesn\'t goes in to much detail.

Thanks
JM


You didn\'t say if this lack is for high power versus low power or at
high speed or static etc. But you might find what you are looking for by
browsing archive manufacturers applications handbooks and databook
compendiums from the mid 1970s thru early 1980s. This is the period when
switch mode power supplies were taking off and before mosfets took over
the switch role. Some had innovative ways of dealing with storage time
and SOA etc and methods to evaluate and select.

The application notes for Ferranti e-line transistors (small signal) is
online and quite a nice introduction to BJT design (though dated).

http://www.introni.it/pdf/Ferranti%20-%20E%20Line%20Transistor%20Applications%201974.pdf

Back in the days when some logics was still done in discrete parts.
For a more theoretical take, this excerpt adapts the small-signal
hybrid-π model to large-signal switching:

https://crcomp.net/smps/bjt.pdf

Danke,

--
Don, KB7RPU, https://www.qsl.net/kb7rpu
There was a young lady named Bright Whose speed was far faster than light;
She set out one day In a relative way And returned on the previous night.

Thank you very much for the references.
Amazing!
These are very useful and hard to find, unless you know exactly what
to look for and here.
I was actually thinking of a much simpler use, like driving a LED or a
solenoid, but I guess I will find what I\'m looking for in one of these
texts.
What a shame these things are not teached at the university.
Cheers
JM

Picking a base resistor that\'s guaranteed to force a base current
greater than Ic/beta when the transistor is in saturation, at the
minimum base current specified for that device at that collector
current, tends to be good enough for low-speed low power tasks like
switching small solenoids and LEDs, don\'t need to over-think it too much.

For high-current and/or high-speed switching where stuff like
temperature de-rating, SOA, charge storage, etc. would become important
for BJTs the power FET is often the more appropriate tool for the job in
year of our Lord 2021. De-rating is easier for the FET I think; BJTs in
power switching applications tend to end up very de-rated cuz there\'s a
lot to go wrong with power switch BJTs pushed to their limits,
insufficient base drive makes them very unhappy for example.

 

[bitrex]

On 12/9/21 2:53 PM, bitrex wrote:

On 12/9/21 1:51 PM, jmariano wrote:
On Thursday, 9 December 2021 at 15:20:06 UTC, Don wrote:
Martin Brown wrote:
piglet wrote:
jmariano wrote:
Dear All,

I was wondering if someone could direct me to a text or book that
explains all the steps needed to calculate the circuit parameters
of a
BJT used a switch, preferably with real examples using data from the
datasheet. I\'ve been using these thing all my live, but now I realize
that my design process had to much guess work and trial and error to
be serious.

I have searched the web, but all texts I was able to find were too
simple, directed to the non initiated hobbyist. I often use \"the art
of electronics\", but on this regard, PH doesn\'t goes in to much
detail.

Thanks
JM


You didn\'t say if this lack is for high power versus low power or at
high speed or static etc. But you might find what you are looking
for by
browsing archive manufacturers applications handbooks and databook
compendiums from the mid 1970s thru early 1980s. This is the period
when
switch mode power supplies were taking off and before mosfets took
over
the switch role. Some had innovative ways of dealing with storage time
and SOA etc and methods to evaluate and select.

The application notes for Ferranti e-line transistors (small signal) is
online and quite a nice introduction to BJT design (though dated).

http://www.introni.it/pdf/Ferranti%20-%20E%20Line%20Transistor%20Applications%201974.pdf


Back in the days when some logics was still done in discrete parts.
For a more theoretical take, this excerpt adapts the small-signal
hybrid-π model to large-signal switching:

https://crcomp.net/smps/bjt.pdf

Danke,

--
Don, KB7RPU, https://www.qsl.net/kb7rpu
There was a young lady named Bright Whose speed was far faster than
light;
She set out one day In a relative way And returned on the previous
night.

Thank you very much for the references.
Amazing!
These are very useful and hard to find, unless you know exactly what
to look for and here.
I was actually thinking of a much simpler use, like driving a LED or a
solenoid, but I guess I will find what I\'m looking for in one of these
texts.
What a shame these things are not teached at the university.
Cheers
JM


Picking a base resistor that\'s guaranteed to force a base current
greater than Ic/beta when the transistor is in saturation, at the
minimum base current

Minimum beta, rather

 

[Don]

jmariano wrote:
> Don wrote:

<snip>

For a more theoretical take, this excerpt adapts the small-signal
hybrid-π model to large-signal switching:

https://crcomp.net/smps/bjt.pdf

Thank you very much for the references.
Amazing!
These are very useful and hard to find, unless you know exactly what
to look for and here.
I was actually thinking of a much simpler use, like driving a LED or a
solenoid, but I guess I will find what I\'m looking for in one of these
texts.
What a shame these things are not teached at the university.

My excerpt comes from my old University of Colorado textbook. So, the
University of Colorado, at least, does indeed teach this theory.

Danke,

--
Don, KB7RPU, https://www.qsl.net/kb7rpu
There was a young lady named Bright Whose speed was far faster than light;
She set out one day In a relative way And returned on the previous night.

 

[Martin Brown]

On 09/12/2021 19:57, Don wrote:

jmariano wrote:
Don wrote:

snip

For a more theoretical take, this excerpt adapts the small-signal
hybrid-π model to large-signal switching:

https://crcomp.net/smps/bjt.pdf

Thank you very much for the references.
Amazing!
These are very useful and hard to find, unless you know exactly what
to look for and here.
I was actually thinking of a much simpler use, like driving a LED or a
solenoid, but I guess I will find what I\'m looking for in one of these
texts.
What a shame these things are not teached at the university.

My excerpt comes from my old University of Colorado textbook. So, the
University of Colorado, at least, does indeed teach this theory.

We did get quite an extensive electronics course in the second year.
I was from the FET era, and studying physics. The physics practicals
considered their behaviour had far more physics content than bipolars.

They did have an unfortunate tendency to die due to static though.

--
Regards,
Martin Brown

 

[jmariano]

On Friday, 10 December 2021 at 08:45:35 UTC, Martin Brown wrote:

On 09/12/2021 19:57, Don wrote:
jmariano wrote:
Don wrote:

snip

For a more theoretical take, this excerpt adapts the small-signal
hybrid-π model to large-signal switching:

https://crcomp.net/smps/bjt.pdf

Thank you very much for the references.
Amazing!
These are very useful and hard to find, unless you know exactly what
to look for and here.
I was actually thinking of a much simpler use, like driving a LED or a
solenoid, but I guess I will find what I\'m looking for in one of these
texts.
What a shame these things are not teached at the university.

My excerpt comes from my old University of Colorado textbook. So, the
University of Colorado, at least, does indeed teach this theory.
We did get quite an extensive electronics course in the second year.
I was from the FET era, and studying physics. The physics practicals
considered their behaviour had far more physics content than bipolars.

They did have an unfortunate tendency to die due to static though.

--
Regards,
Martin Brown

I have indeed used MOSFET in some hig-current applications (LED driver) with the help of people here, but I thought I\'d brush up on my BJT in my current project.
I\'m aware that MOSFET is the way to go, but nevertheless.... I even intend to use a discreate darlington pair to control a motor, just for the sake it.

I also studied FETs on my electronics classes for physicist, but they were all rather teorectical, even the labs.
I\'m allways looking for these rules-of-tumb that you get from practitioners of engineering.
This is why I value google groups so much!
Thanks to you all!

Regards
JM