Repair/replace 7CT1N?

[Robert Baer]

jlarkin@highlandsniptechnology.com wrote:

On Mon, 4 May 2020 16:29:49 -0700, Robert Baer
robertbaer@localnet.com> wrote:

John Larkin wrote:
On Mon, 4 May 2020 12:40:49 -0700, Robert Baer
robertbaer@localnet.com> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Sat, 2 May 2020 18:22:52 -0700, Robert Baer
robertbaer@localnet.com> wrote:

Mine quit - no vertical output.

Ideas? quotes? Etc?

Thanks.

What do you use a curve tracer for?



Part matching, spec conformance/non-conformance, check off-datasheet
specs, etc

Matching soulds iffy, on an analog oscilloscope curve tracer. Better
to design so that any data-sheet-conforming parts work.



On some of my designs, the part datasheet has no spec or a
non-meaningful value.
For example, there is no bipolar transistor datasheet spec for the
E-B junction zener voltage; "5V max" if at all.
I dare you to find a bipolar with a 6.2V zener breakdown by using the
datasheet.
Or 9.5V zener breakdown.
Tempco of that Vz?
So you gotta measure and best with curve tracer so you know how
sharp, if avalanches, etc.
And one can easily match within 10mV.


Can you read Vz and the tempco of Vz, to millivolts, off the screen of
an analog scope? I can do that easily on a DVM. I think the diode
range of my Fluke is 1 mA up to 10 volts.

If you use a be junction as a zener, you should be careful that it's
repeatable.

Some transistors are accidentally 6.2v "reference zeners" from
collector to emitter with the base open. But's that's probably not
suited to production.

and..that open base makes it rather sensitive to package leakages,
as well as partly sensitive to external EMI.

 

On Mon, 4 May 2020 23:23:14 -0700, Robert Baer
<robertbaer@localnet.com> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Mon, 4 May 2020 16:29:49 -0700, Robert Baer
robertbaer@localnet.com> wrote:

John Larkin wrote:
On Mon, 4 May 2020 12:40:49 -0700, Robert Baer
robertbaer@localnet.com> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Sat, 2 May 2020 18:22:52 -0700, Robert Baer
robertbaer@localnet.com> wrote:

Mine quit - no vertical output.

Ideas? quotes? Etc?

Thanks.

What do you use a curve tracer for?



Part matching, spec conformance/non-conformance, check off-datasheet
specs, etc

Matching soulds iffy, on an analog oscilloscope curve tracer. Better
to design so that any data-sheet-conforming parts work.



On some of my designs, the part datasheet has no spec or a
non-meaningful value.
For example, there is no bipolar transistor datasheet spec for the
E-B junction zener voltage; "5V max" if at all.
I dare you to find a bipolar with a 6.2V zener breakdown by using the
datasheet.
Or 9.5V zener breakdown.
Tempco of that Vz?
So you gotta measure and best with curve tracer so you know how
sharp, if avalanches, etc.
And one can easily match within 10mV.


Can you read Vz and the tempco of Vz, to millivolts, off the screen of
an analog scope? I can do that easily on a DVM. I think the diode
range of my Fluke is 1 mA up to 10 volts.

If you use a be junction as a zener, you should be careful that it's
repeatable.

Some transistors are accidentally 6.2v "reference zeners" from
collector to emitter with the base open. But's that's probably not
suited to production.



and..that open base makes it rather sensitive to package leakages,
as well as partly sensitive to external EMI.

Not really. The c-b junction is forward biased and b-e is zenering
(collector is negative for an NPN) so there's no transistor action.



--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard