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From: "n4buq" <n4buq@...>
To: "tekscopes" <[email protected]>
Sent: Tuesday, May 31, 2022 10:10:51 AM
Subject: Interpreting Transistor Curve Traces

Now that I've had some time to accustom myself with my 7CT1N, while I can make
lots of pretty pictures, I'd like a better understanding of what information I
can glean from the results, particularly for bipolar transistors

From what I understand, STEP AMPLITUDE is an indicator of fixed base current per
step and the AMPERES/DIV determines the vertical scaling. If the STEP
AMPLITUDE is set to 10uA and the AMPERES/DIV is at 10mA, if I display just two
traces and the vertical spacing of the linear portions of the horizontal lines
is 1 division, I presume that indicates the transistor's current gain is
10mA/10uA = 1000. Is that correct?

Also, I'm curious as to how to properly set this up with the tracer in a
horizontal slot and using a vertical amplifier. With this configuration, I can
change the vertical attenuation as I want and, thus, am not sure how to
calculate a proper vertical AMPERES/DIVISION value. Using it in the reverse
way (the tracer in a vertical slot and a time-base capable of acting as an
amplifier in a horizontal slot or just an ordinary amplifier in a horizontal
slot), I don't have control over the vertical attenuation and I presume the
AMPERES/DIVISION is direct-reading but that might not be correct.

Apologies if this is extremely basic information that should be obvious to me by
now.

Thanks,
Barry - N4BUQ

From: "n4buq" <n4buq@...>
To: "tekscopes" <[email protected]>
Sent: Tuesday, May 31, 2022 10:10:51 AM
Subject: Interpreting Transistor Curve Traces

Now that I've had some time to accustom myself with my 7CT1N, while I
can make lots of pretty pictures, I'd like a better understanding of
what information I can glean from the results, particularly for
bipolar transistors

From what I understand, STEP AMPLITUDE is an indicator of fixed base
current per step and the AMPERES/DIV determines the vertical scaling.
If the STEP AMPLITUDE is set to 10uA and the AMPERES/DIV is at 10mA,
if I display just two traces and the vertical spacing of the linear
portions of the horizontal lines is 1 division, I presume that
indicates the transistor's current gain is 10mA/10uA = 1000. Is that correct?

Also, I'm curious as to how to properly set this up with the tracer in
a horizontal slot and using a vertical amplifier. With this
configuration, I can change the vertical attenuation as I want and,
thus, am not sure how to calculate a proper vertical AMPERES/DIVISION
value. Using it in the reverse way (the tracer in a vertical slot and
a time-base capable of acting as an amplifier in a horizontal slot or
just an ordinary amplifier in a horizontal slot), I don't have control
over the vertical attenuation and I presume the AMPERES/DIVISION is direct-reading but that might not be correct.

Apologies if this is extremely basic information that should be
obvious to me by now.

Thanks,
Barry - N4BUQ

From: "si_emi_01" <wellington@...>
To: "tekscopes" <[email protected]>
Sent: Tuesday, May 31, 2022 1:02:47 PM
Subject: Re: [TekScopes] Interpreting Transistor Curve Traces

Hi Barry,

Another good reference for using a Curve Tracer is:
Tektronix Measurement Concepts
Tektronix - Semiconductor Device Measurement - 1970 (062-1009-00)

It's available on the TekWiki at:


Ross

-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of n4buq
Sent: Tuesday, May 31, 2022 10:45 AM
To: tekscopes <[email protected]>
Subject: Re: [TekScopes] Interpreting Transistor Curve Traces

I see where the manual covers this so I'll study on that before asking more
questions.

Thanks,
Barry - N4BUQ

----- Original Message -----

From: "n4buq" <n4buq@...>
To: "tekscopes" <[email protected]>
Sent: Tuesday, May 31, 2022 10:10:51 AM
Subject: Interpreting Transistor Curve Traces

Now that I've had some time to accustom myself with my 7CT1N, while I
can make lots of pretty pictures, I'd like a better understanding of
what information I can glean from the results, particularly for
bipolar transistors

From what I understand, STEP AMPLITUDE is an indicator of fixed base
current per step and the AMPERES/DIV determines the vertical scaling.
If the STEP AMPLITUDE is set to 10uA and the AMPERES/DIV is at 10mA,
if I display just two traces and the vertical spacing of the linear
portions of the horizontal lines is 1 division, I presume that
indicates the transistor's current gain is 10mA/10uA = 1000. Is that correct?

Also, I'm curious as to how to properly set this up with the tracer in
a horizontal slot and using a vertical amplifier. With this
configuration, I can change the vertical attenuation as I want and,
thus, am not sure how to calculate a proper vertical AMPERES/DIVISION
value. Using it in the reverse way (the tracer in a vertical slot and
a time-base capable of acting as an amplifier in a horizontal slot or
just an ordinary amplifier in a horizontal slot), I don't have control
over the vertical attenuation and I presume the AMPERES/DIVISION is
direct-reading but that might not be correct.

Apologies if this is extremely basic information that should be
obvious to me by now.

Thanks,
Barry - N4BUQ

From: "si_emi_01" <wellington@...>
To: "tekscopes" <[email protected]>
Sent: Tuesday, May 31, 2022 1:02:47 PM
Subject: Re: [TekScopes] Interpreting Transistor Curve Traces

Hi Barry,

Another good reference for using a Curve Tracer is:
Tektronix Measurement Concepts
Tektronix - Semiconductor Device Measurement - 1970 (062-1009-00)

It's available on the TekWiki at:


Ross

-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of n4buq
Sent: Tuesday, May 31, 2022 10:45 AM
To: tekscopes <[email protected]>
Subject: Re: [TekScopes] Interpreting Transistor Curve Traces

I see where the manual covers this so I'll study on that before asking
more questions.

Thanks,
Barry - N4BUQ

----- Original Message -----

From: "n4buq" <n4buq@...>
To: "tekscopes" <[email protected]>
Sent: Tuesday, May 31, 2022 10:10:51 AM
Subject: Interpreting Transistor Curve Traces

Now that I've had some time to accustom myself with my 7CT1N, while I
can make lots of pretty pictures, I'd like a better understanding of
what information I can glean from the results, particularly for
bipolar transistors

From what I understand, STEP AMPLITUDE is an indicator of fixed base
current per step and the AMPERES/DIV determines the vertical scaling.
If the STEP AMPLITUDE is set to 10uA and the AMPERES/DIV is at 10mA,
if I display just two traces and the vertical spacing of the linear
portions of the horizontal lines is 1 division, I presume that
indicates the transistor's current gain is 10mA/10uA = 1000. Is that correct?

Also, I'm curious as to how to properly set this up with the tracer
in a horizontal slot and using a vertical amplifier. With this
configuration, I can change the vertical attenuation as I want and,
thus, am not sure how to calculate a proper vertical AMPERES/DIVISION
value. Using it in the reverse way (the tracer in a vertical slot
and a time-base capable of acting as an amplifier in a horizontal
slot or just an ordinary amplifier in a horizontal slot), I don't
have control over the vertical attenuation and I presume the
AMPERES/DIVISION is direct-reading but that might not be correct.

Apologies if this is extremely basic information that should be
obvious to me by now.

Thanks,
Barry - N4BUQ

From: "EJP" <esmond.pitt@...>
To: "tekscopes" <[email protected]>
Sent: Tuesday, May 31, 2022 8:17:18 PM
Subject: Re: [TekScopes] Interpreting Transistor Curve Traces

On Wed, Jun 1, 2022 at 01:10 AM, n4buq wrote:

If the STEP
AMPLITUDE is set to 10uA and the AMPERES/DIV is at 10mA, if I display just two
traces and the vertical spacing of the linear portions of the horizontal lines
is 1 division, I presume that indicates the transistor's current gain is
10mA/10uA = 1000. Is that correct?

Yes. See manual p.1-8. beta = VERTICAL AMPS per DIV/STEP AMPL.

Also, I'm curious as to how to properly set this up with the tracer in a
horizontal slot and using a vertical amplifier. With this configuration, I can
change the vertical attenuation as I want

No. You are supposed to set the vertical amplifier to 100mV/div, and then
control everything else on the 7CT1N. See manual p.1-1.

I presume the
AMPERES/DIVISION is direct-reading but that might not be correct.

Correct, with the 100mV/div proviso above.

EJP