Topics

Yet another use for a curve tracer


Ed Breya
 

I've been cleaning up and organizing lots of stuff lately, and I found I had a couple dozen various AC light dimmers and fan controls piled up. After I eliminated the obvious junkers - marked bad, taken apart, busted parts, etc - I had about a dozen left, to save for possible re-use. I decided to check them out on the curve tracer, to eliminate any more bad ones from stock.

I set up the 576 for AC, 350 V peak range, series R 680 ohms, H 50 V/div, V 100 mA/div, and started testing. It worked great, and all of the two-terminal types checked OK. There are some three- and four-terminal ones that need further study to figure out appropriate hookup. Here's the process, for two-terminal types:

1. Set collector supply to zero.
2. Hook up dimmer.
3 Set collector to about 175 V peak.
4. Run dimmer knob through OFF and full range.
5. Display appearance should change according to dimmer setting, from a flat line or small "+" to a large "+," indicating proper operation.
6. Turn collector back to zero.
7. Disconnect dimmer, and connect the next one.
Repeat as needed.

Ed


Daveolla
 

Does it not need a minimum load. I just hook them up to the AC cord and a light bulb. I guess I'm stupid for keeping it simple (KISS)

There were opinions earlier on other brand Curve Tracers, EICO and Heath, any opinions from the group on the BK 501A Curve Tracer?

Dave

At 08:18 PM 12/04/2020, you wrote:
I've been cleaning up and organizing lots of stuff lately, and I found I had a couple dozen various AC light dimmers and fan controls piled up. After I eliminated the obvious junkers - marked bad, taken apart, busted parts, etc - I had about a dozen left, to save for possible re-use. I decided to check them out on the curve tracer, to eliminate any more bad ones from stock.

I set up the 576 for AC, 350 V peak range, series R 680 ohms, H 50 V/div, V 100 mA/div, and started testing. It worked great, and all of the two-terminal types checked OK. There are some three- and four-terminal ones that need further study to figure out appropriate hookup. Here's the process, for two-terminal types:

1. Set collector supply to zero.
2. Hook up dimmer.
3 Set collector to about 175 V peak.
4. Run dimmer knob through OFF and full range.
5. Display appearance should change according to dimmer setting, from a flat line or small "+" to a large "+," indicating proper operation.
6. Turn collector back to zero.
7. Disconnect dimmer, and connect the next one.
Repeat as needed.

Ed



Ed Breya
 

The old-fashioned way would work too, but this was simplest for me to turn it on and set up. The whole thing took only a few minutes to check them all. It would take me much longer just to find a bulb socket - I know I should have one somewhere around here.

Ed


-
 

I don't have a BK 501 but I do have a B&K 540 "Component tester". It's a
small AC powered unit with about a 2 1/2" CRT. The whole thing is about 7
inches wide and about 2 1/2" tall and about 10" deep. IIRC it has two
current ranges and two voltage ranges and it's strictly an I-V tester so
it's not nearly as accurate as the Tektronix curve tracers but it is a
*very* *handy* device to keep on the bench for quick testing of
semiconductors and for identifying passive devices. IIRC it's the same or
very similar to the Polar T1200 component tester.

I have the manual for a B&K 501A and it looks like a decent unit but it
doesn't the capabilities of a Tektronix Curve Tracer but it will display
multiple current steps. It would also be easy to add a variac to it to get
the continuously variable collector voltage capability.

I also have a Hicock unit similar to the B&K 501 but it also has the
capability of testing vacuum tubes. I'm looking for a manual or even just
the specs for it if anyone has them.

On Fri, Dec 4, 2020 at 10:19 PM Daveolla <grobbins@netflash.net> wrote:

Does it not need a minimum load. I just hook them up to the AC cord
and a light bulb. I guess I'm stupid for keeping it simple (KISS)

There were opinions earlier on other brand Curve Tracers, EICO
and Heath, any opinions from the group on the BK 501A Curve Tracer?

Dave



At 08:18 PM 12/04/2020, you wrote:
I've been cleaning up and organizing lots of stuff lately, and I
found I had a couple dozen various AC light dimmers and fan controls
piled up. After I eliminated the obvious junkers - marked bad, taken
apart, busted parts, etc - I had about a dozen left, to save for
possible re-use. I decided to check them out on the curve tracer, to
eliminate any more bad ones from stock.

I set up the 576 for AC, 350 V peak range, series R 680 ohms, H 50
V/div, V 100 mA/div, and started testing. It worked great, and all
of the two-terminal types checked OK. There are some three- and
four-terminal ones that need further study to figure out appropriate
hookup. Here's the process, for two-terminal types:

1. Set collector supply to zero.
2. Hook up dimmer.
3 Set collector to about 175 V peak.
4. Run dimmer knob through OFF and full range.
5. Display appearance should change according to dimmer setting,
from a flat line or small "+" to a large "+," indicating proper operation.
6. Turn collector back to zero.
7. Disconnect dimmer, and connect the next one.
Repeat as needed.

Ed









Daveolla
 

Thanks, "- " (or can I call you "Dash"?...........Prince used a symbol for a bit also, so at least your in good company) I have a B&K 501A and manual but just never got around to using it. I did spend a bit of time making a triple banana plug to 2 bnc plugs cord to use for it, but thats as far as I got. I have been meaning to make the missing scope graticule . There is a pic in the manual of it that should be easy to fix up the image and copy onto a clear transparency. Perhaps a scan of the original maybe handy if someone wants to copy it, but I have done enuf image fixing that I shouldn't need it.. Presently I am fixing a manual I downloaded from the Amprobe site that has all the pages crooked, some near off by 45 degrees. You would think a company would want to represent them selves a little more dignity, I would be embarrassed if I did a scan a like this to show it to anyone, let alone the whole world!!!!!

Dave

At 10:33 PM 12/04/2020, you wrote:
I don't have a BK 501 but I do have a B&K 540 "Component tester". It's a
small AC powered unit with about a 2 1/2" CRT. The whole thing is about 7
inches wide and about 2 1/2" tall and about 10" deep. IIRC it has two
current ranges and two voltage ranges and it's strictly an I-V tester so
it's not nearly as accurate as the Tektronix curve tracers but it is a
*very* *handy* device to keep on the bench for quick testing of
semiconductors and for identifying passive devices. IIRC it's the same or
very similar to the Polar T1200 component tester.

I have the manual for a B&K 501A and it looks like a decent unit but it
doesn't the capabilities of a Tektronix Curve Tracer but it will display
multiple current steps. It would also be easy to add a variac to it to get
the continuously variable collector voltage capability.

I also have a Hicock unit similar to the B&K 501 but it also has the
capability of testing vacuum tubes. I'm looking for a manual or even just
the specs for it if anyone has them.

On Fri, Dec 4, 2020 at 10:19 PM Daveolla <grobbins@netflash.net> wrote:

Does it not need a minimum load. I just hook them up to the AC cord
and a light bulb. I guess I'm stupid for keeping it simple (KISS)

There were opinions earlier on other brand Curve Tracers, EICO
and Heath, any opinions from the group on the BK 501A Curve Tracer?

Dave


 

Hi Ed,
Curve tracers are very versatile instruments and the only real limitation they have is the person at the controls.
Nearly everyone I know who owns a curve tracer thinks they are only good for checking transistors.

What you did was think outside the box, and as you said in the subject, you found another use for a curve tracer.
I hadn't thought of using it to test lamp dimmers myself so I learned something new.
But I have used it to test capacitors, inductors, transformers, pots, SCRs, TRIACs, DIACs, MOVs, OpAmps, Voltage Regulators ICs, Spectrum Tubes, light bulbs, etc.
Anything with two or three leads is fair game for a curve tracer.

Anyone who owns a curve tracer is extremely fortunate. You can learn a great deal about how electronic parts of all kinds respond when you connect them to a curve tracer.

Thanks for sharing your clever idea.

Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Ed Breya via groups.io
Sent: Friday, December 04, 2020 7:52 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Yet another use for a curve tracer

The old-fashioned way would work too, but this was simplest for me to turn it on and set up. The whole thing took only a few minutes to check them all. It would take me much longer just to find a bulb socket - I know I should have one somewhere around here.

Ed







--
Dennis Tillman W7pF
TekScopes Moderator


@0culus
 

Dennis,

This is most definitely true. I got me a very nice 577D1 on the same trip I picked up my 519 on, and suffice to say, I am discovering something new it can do every day. Now to collect all the handy test fixtures Tek made...

Sean

On Tue, Dec 8, 2020 at 10:53 AM, Dennis Tillman W7pF wrote:


Hi Ed,
Curve tracers are very versatile instruments and the only real limitation they
have is the person at the controls.
Nearly everyone I know who owns a curve tracer thinks they are only good for
checking transistors.

What you did was think outside the box, and as you said in the subject, you
found another use for a curve tracer.
I hadn't thought of using it to test lamp dimmers myself so I learned
something new.
But I have used it to test capacitors, inductors, transformers, pots, SCRs,
TRIACs, DIACs, MOVs, OpAmps, Voltage Regulators ICs, Spectrum Tubes, light
bulbs, etc.
Anything with two or three leads is fair game for a curve tracer.

Anyone who owns a curve tracer is extremely fortunate. You can learn a great
deal about how electronic parts of all kinds respond when you connect them to
a curve tracer.

Thanks for sharing your clever idea.

Dennis Tillman W7pF


 

Hi Sean,
Lucky you to own a 577D1!

One clever thing you can do with the 577D1 that no other Tek curve tracer can do is find the perfect bias point for a junction FET. You should bias a FET right at the point where the temp coefficient is zero but how do you find that point except by trial and error? FETs are very temperature sensitive little critters with a very unusual temperature coefficient. It is positive up to a certain point and then it turns negative. For your circuit's best temperature stability you need to bias a FET right at the point where the temp coefficient is zero but how do you find that point except by trial and error?
The 577D1 can find that exact zero temperature coefficient point to bias the FET in less than 30 seconds.

Here is how to do it: Display a set of typical FET curves on the 577D1 with storage turned on. Heat the FET up with your finger, or with anything hot for just a second. As the FET die warms up the gate voltage curves will begin to move up above a certain bias voltage and they will move down below that voltage.

The result on the CRT will be that one gate voltage curve will not move so it will remain sharp. All the other bias voltage curves will smear as they move away from the perfect point to bias the FET.

You can also use something cold like an ice cube touched to the FET. The results will be the same except the smears will go in the opposite direction. But one bias curve right in the middle of the smeared ones will be sharp because it didn't move at all.

Give it a try. It is fascinating to watch and it only takes a minute to do this and it is a perfect example of yet another use for a curve tracer. But in this case it is hard to do without storage so that is another reason why my favorite curve tracer is the 577D1.

Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of sdturne@q.com
Sent: Tuesday, December 08, 2020 6:38 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Yet another use for a curve tracer

Dennis,

This is most definitely true. I got me a very nice 577D1 on the same trip I picked up my 519 on, and suffice to say, I am discovering something new it can do every day. Now to collect all the handy test fixtures Tek made...

Sean

On Tue, Dec 8, 2020 at 10:53 AM, Dennis Tillman W7pF wrote:


Hi Ed,
Curve tracers are very versatile instruments and the only real
limitation they have is the person at the controls.
Nearly everyone I know who owns a curve tracer thinks they are only
good for checking transistors.

What you did was think outside the box, and as you said in the
subject, you found another use for a curve tracer.
I hadn't thought of using it to test lamp dimmers myself so I learned
something new.
But I have used it to test capacitors, inductors, transformers, pots,
SCRs, TRIACs, DIACs, MOVs, OpAmps, Voltage Regulators ICs, Spectrum
Tubes, light bulbs, etc.
Anything with two or three leads is fair game for a curve tracer.

Anyone who owns a curve tracer is extremely fortunate. You can learn a
great deal about how electronic parts of all kinds respond when you
connect them to a curve tracer.

Thanks for sharing your clever idea.

Dennis Tillman W7pF






--
Dennis Tillman W7pF
TekScopes Moderator


@0culus
 

Dennis,

That is super cool. Definitely going to have to find one and try that out.

I was happy to find a D1, particularly a D1 that works with the crt in decent shape (a couple of burns from someone leaving a bright dot, but otherwise very crisp and bright)!

Sean

On Wed, Dec 9, 2020 at 01:24 PM, Dennis Tillman W7pF wrote:


Hi Sean,
Lucky you to own a 577D1!

One clever thing you can do with the 577D1 that no other Tek curve tracer can
do is find the perfect bias point for a junction FET. You should bias a FET
right at the point where the temp coefficient is zero but how do you find that
point except by trial and error? FETs are very temperature sensitive little
critters with a very unusual temperature coefficient. It is positive up to a
certain point and then it turns negative. For your circuit's best temperature
stability you need to bias a FET right at the point where the temp coefficient
is zero but how do you find that point except by trial and error?
The 577D1 can find that exact zero temperature coefficient point to bias the
FET in less than 30 seconds.

Here is how to do it: Display a set of typical FET curves on the 577D1 with
storage turned on. Heat the FET up with your finger, or with anything hot for
just a second. As the FET die warms up the gate voltage curves will begin to
move up above a certain bias voltage and they will move down below that
voltage.

The result on the CRT will be that one gate voltage curve will not move so it
will remain sharp. All the other bias voltage curves will smear as they move
away from the perfect point to bias the FET.

You can also use something cold like an ice cube touched to the FET. The
results will be the same except the smears will go in the opposite direction.
But one bias curve right in the middle of the smeared ones will be sharp
because it didn't move at all.

Give it a try. It is fascinating to watch and it only takes a minute to do
this and it is a perfect example of yet another use for a curve tracer. But in
this case it is hard to do without storage so that is another reason why my
favorite curve tracer is the 577D1.

Dennis Tillman W7pF
toggle quoted message Show quoted text ( #quoted-176906727 )


Jean-Paul
 

Hello all: We have a fine 576 with the pulsed high current test fixture and many adapters.

One unusual use has been testing gas discharge lamps, Telecom protection spark gaps, neon, etc,
Set on AC, 0.5 or 2.3 W, up to 1500V
No base connection needed. Gas Breakdown voltage and ON impedance are easily checked.

Another use is checking LEDs,
There are some that are very high power and others that are prototype tubular filament LED.
Like a diode but with many series junctions, so voltage forward can be 30-100V.

Enjoy,

Jon


Miguel Work
 

Yes, I use my 576 to check led backlight

And my 176 to test fake xinese transistors and mosfets to 200A

-----Mensaje original-----
De: TekScopes@groups.io [mailto:TekScopes@groups.io] En nombre de Jean-Paul
Enviado el: viernes, 11 de diciembre de 2020 10:51
Para: TekScopes@groups.io
Asunto: Re: [TekScopes] Yet another use for a curve tracer

Hello all: We have a fine 576 with the pulsed high current test fixture and many adapters.

One unusual use has been testing gas discharge lamps, Telecom protection spark gaps, neon, etc, Set on AC, 0.5 or 2.3 W, up to 1500V No base connection needed. Gas Breakdown voltage and ON impedance are easily checked.

Another use is checking LEDs,
There are some that are very high power and others that are prototype tubular filament LED.
Like a diode but with many series junctions, so voltage forward can be 30-100V.

Enjoy,

Jon







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Jean-Paul
 

Rebonjour,

No TEK adapters exist For lamp and LED testing.
We made binding post adapters for the test fixtures, two male banana plugs and two small pieces are acrylic plastic, in a sandwich separated by stand-offs.

The 576 is huge and dominantes a bench, It is a fine instrument for power electronics and lighting control development. Only service in 25 years, replaced the gratiticule or fiber optic display lamps.

Ever see the SCR turnoff time test adapter?

Bon journée
Jon


Tom Bowers
 

Yet another use for a Curve Tracer;

In the 1970s we were having a problem with a custom digital logic family
and interconnect through long twisted pair wiring. A transmission line
problem. The wiring was hundreds of signals, about 80 ohms characteristic
impedance, maybe 6 to 10 feet long, and driven with 5 to 7 nS edge rates.
The transmission lines were terminated in logic gates. Once I put a
receiver logic gate on the 576 CT to analyze the termination impedance I
could immediately see the non-linear termination. It transitioned from a
low impedance clamp diode below ground, to logic low impedance, then higher
impedance above the TTL threshold.

The device under test was powered from a separate power supply. A common
Ground was connected to the 576 "E" terminal, grounded. The "C" terminal
connected to the device under test logic input and the 576 was used in AC
mode to view the logic gate V/I curve. Once I understood this
characteristic, I could figure out how to add additional transmission line
termination techniques to get the digital signal working properly. TEK 576
to the rescue! I've had one available for use ever since.

Tom Bowers
PVH Engineering

On Fri, Dec 11, 2020 at 3:41 AM Jean-Paul <jonpaul@ix.netcom.com> wrote:

Rebonjour,

No TEK adapters exist For lamp and LED testing.
We made binding post adapters for the test fixtures, two male banana plugs
and two small pieces are acrylic plastic, in a sandwich separated by
stand-offs.

The 576 is huge and dominantes a bench, It is a fine instrument for
power electronics and lighting control development. Only service in 25
years, replaced the gratiticule or fiber optic display lamps.

Ever see the SCR turnoff time test adapter?

Bon journée
Jon