Date   

Re: OT- inexpensive but feature rich curve tracer

Craig Sawyers <c.sawyers@...>
 

saving up to buy a Peak DCA55 component analyzer and now I see they have
an updated/improved model, the DCA75. It analyzes all kinds of
semiconductors and connects to a computer to do basic curve tracing. The
software is very straightforward and the data can be exported in standard
excel format.
That is astonishing value for money! Want one....

Craig


OT- inexpensive but feature rich curve tracer

Jamie
 

While many of us here would love to have a 576 it's simply not in the budget and many will not want to repair one if purchased needing work. I've been saving up to buy a Peak DCA55 component analyzer and now I see they have an updated/improved model, the DCA75. It analyzes all kinds of semiconductors and connects to a computer to do basic curve tracing. The software is very straightforward and the data can be exported in standard excel format.

It's limited to +- 12 volts and 5ma but for many of us that's sufficient. The DCA75 allows you to clip three leads to almost any random unidentified part and find all kinds of information about it from pinout to leakage to current gain. It's found a home on the bench of many guitar effect builders because it allows them to accurately characterize germanium transistors for guitar fuzz pedals. Similarly, it can match jfet pinch voltages and measure transconductance. I'd imagine it's also popular with hifi and audio recording designers for these reasons.

I thought I'd pass it on for those that are interested- sorry to be off-topic. As many of you know, you can gain more "real" knowledge with your own curve tracer than several semesters of semiconductor theory in college. This unit puts practical learning and measurement in the hands of all but the most austere of home labs.

here's a link: http://www.peakelec.co.uk/acatalog/dca75-dca-pro.html

Jamie


Re: Curve Tracer Test Temperature, Was Wanted: 7CT1N Curve Tracer Plug-In

Don Black <donald_black@...>
 

Thanks David, a valuable reference, those three "spare" transistors are very handy. I also had a look at the LM10 OP-Amp/Regulator IC which was mentioned via one of the forums recently. I guess it's obsolete now but what a useful device.

Don Black.

On 23-Mar-13 9:50 PM, David wrote:
 

It is in National Semiconductor Linear Application Note 256,
"Circuitry for Inexpensive Relative Humidity Measurement", although I
was wrong about how it implemented the temperature measurement. It
just measures the forward voltage drop of one of the transistors
instead of an actual delta Vbe measurement because it does not require
absolute accuracy.

You can find it in the first application note here:

http://www.introni.it/pdf/Williams%2008%20-%20NSC%20Application%20Notes.pdf

I have seen the same temperature controlled logarithmic amplifier
trick implemented with a CA-3086 transistor array as well although it
would apply to any monolithic transistor array.

On Sat, 23 Mar 2013 17:43:38 +1100, Don Black
<donald_black@...> wrote:

>Hi David, do you have a link to the circuit using the LM389 please, I'd
>like to see how it's used.
>
>Thanks, Don Black.
>
>On 23-Mar-13 4:21 AM, David wrote:
>>
>> On Fri, 22 Mar 2013 09:41:55 -0700, Jon Kirwan
>> <jonk@... > wrote:
>>
>> I remember one clever log/antilog amplifier that used the National
>> LM389 to implement the above temperature regulation scheme. It was
>> amazingly cost effective since no temperature compensation was needed.
>> I would still be using it if the LM389 was not discontinued.



Re: Curve Tracer Test Temperature, Was Wanted: 7CT1N Curve Tracer Plug-In

 

It is in National Semiconductor Linear Application Note 256,
"Circuitry for Inexpensive Relative Humidity Measurement", although I
was wrong about how it implemented the temperature measurement. It
just measures the forward voltage drop of one of the transistors
instead of an actual delta Vbe measurement because it does not require
absolute accuracy.

You can find it in the first application note here:

http://www.introni.it/pdf/Williams%2008%20-%20NSC%20Application%20Notes.pdf

I have seen the same temperature controlled logarithmic amplifier
trick implemented with a CA-3086 transistor array as well although it
would apply to any monolithic transistor array.

On Sat, 23 Mar 2013 17:43:38 +1100, Don Black
<donald_black@bigpond.com> wrote:

Hi David, do you have a link to the circuit using the LM389 please, I'd
like to see how it's used.

Thanks, Don Black.

On 23-Mar-13 4:21 AM, David wrote:

On Fri, 22 Mar 2013 09:41:55 -0700, Jon Kirwan
<jonk@infinitefactors.org <mailto:jonk%40infinitefactors.org>> wrote:

I remember one clever log/antilog amplifier that used the National
LM389 to implement the above temperature regulation scheme. It was
amazingly cost effective since no temperature compensation was needed.
I would still be using it if the LM389 was not discontinued.


Re: 7854 waveform calculator on eBay

d.seiter@...
 

Haha, yeah Craig, you guessed it.  I was literally born in silicon valley (back before the traitorous eight).  My high school had a PDP8/E, the usual 1978/9 micros and a link to a HP2000 at the Stanford business school. I learned in the late 80's that Schottky's building was literally a really good stones throw from from my house in Palo Alto.  It was a stereo store for many years and is now a grocery store catering to veggies and euro imports. I used to dumpster dive in my teens at Commodore, Cromemco and Atari.  I once had a top of the line CBM system, including superPET built from scrap, but sold it all in the mid '80s for $200; a steal at the time.

I got my 7854 from a guy on craigslist who was selling a number of them.  I was thinking of making him an offer for the entire lot, but he was *really* sick at the time and I just wanted to get out of there!  

The stores and swap meets aren't that great any longer, and even the auction houses are selling more junk and PCs than usual- I haven't bought anything since the 3 519s a few years ago.   

Time moves on.

-Dave



From: "Craig Sawyers"
To: TekScopes@...
Sent: Saturday, March 23, 2013 12:58:05 AM
Subject: RE: [TekScopes] 7854 waveform calculator on eBay

 

=========================================
I 'm surprised at how much these go for, considering it's basically just a keyboard. I remember back in the late '70s when the local computer store was selling keyboards for about $150. A few years later they became a cheap commodity.

My entire 7854 system (except for the 7b87) cost me $125.

-dave
=========================================

I too am surprised. In fact I considered building one - it is after all just a switch matrix with some data buffers to return row and column to the mainframe. But to purchase the tactile switches and buttons would have been 90% of the cost of buying one.

Dave - when did you manage to get the snip of $125? I have a bunch of tales of things I bought for a few dollars (NIB 7623B for $100, AA501 for $14, A 7L5 with tracking generator for £70 including mainframe, 575 for £40, a whole load of sampling gear for hardly anything) - but these days are a misty recollection, and the days of cheapo stuff seem to be a thing of the past - unless you live in California with all sorts of wonderful swap meets and surplus stores.

Craig


Re: 7S14 broken plastic backplane connector 386-5467-00 [1 Attachment]

coolcoker71
 

I think with a little hot-melt glue, you can tack the board to the plastic part.

> Ed

The plastic is made of Delrin. It is nearly impossible to glue it. Nothing will stick on it like Teflon. You will have to prepare the surface with special chemical.

I will continue looking for a new/old part. Thanks for your post!  


Re: 7854 waveform calculator on eBay

Craig Sawyers <c.sawyers@...>
 

=========================================
I 'm surprised at how much these go for, considering it's basically just a keyboard. I remember back in the late '70s when the local computer store was selling keyboards for about $150. A few years later they became a cheap commodity.

My entire 7854 system (except for the 7b87) cost me $125.

-dave
=========================================

I too am surprised. In fact I considered building one - it is after all just a switch matrix with some data buffers to return row and column to the mainframe. But to purchase the tactile switches and buttons would have been 90% of the cost of buying one.

Dave - when did you manage to get the snip of $125? I have a bunch of tales of things I bought for a few dollars (NIB 7623B for $100, AA501 for $14, A 7L5 with tracking generator for £70 including mainframe, 575 for £40, a whole load of sampling gear for hardly anything) - but these days are a misty recollection, and the days of cheapo stuff seem to be a thing of the past - unless you live in California with all sorts of wonderful swap meets and surplus stores.

Craig


Re: Curve Tracer Test Temperature, Was Wanted: 7CT1N Curve Tracer Plug-In

Don Black <donald_black@...>
 

Hi David, do you have a link to the circuit using the LM389 please, I'd like to see how it's used.

Thanks, Don Black.

On 23-Mar-13 4:21 AM, David wrote:
 

On Fri, 22 Mar 2013 09:41:55 -0700, Jon Kirwan
<jonk@...> wrote:



I remember one clever log/antilog amplifier that used the National
LM389 to implement the above temperature regulation scheme. It was
amazingly cost effective since no temperature compensation was needed.
I would still be using it if the LM389 was not discontinued.



Re: Anti-static bags

David DiGiacomo
 

On Fri, Mar 22, 2013 at 2:32 PM, Dave Daniel <kc0wjn@gmail.com> wrote:
Does anyone have a preferential source for anti-static bags? I can find
lots on the them on the 'net; I'm just wondering if anyone has already
been through the "least cost for low volumes" research and reached a
conclusion.
You probably want metallic ESD bags, not pink poly antistatic bags.

For small quantities, I can recommend:

Courtney Farr
CKC Computers
http://www.ckccomp.com
eBay seller cfarrkc

For larger quantities try:

http://www.dipmicro.com/store/index.php?searchStr=esd&act=viewCat&Submit=Search
http://www.uline.com/Grp_2/Static-Shielding-Bags

If you don't care about ziplock seals, you can save money on small
bags by buying large bags and a bag sealer.

I haven't found any bargains on ESD bags on eBay, but it's a good
place to get a bag sealer.


7L12 first mixer

Chris Leyson
 

My 7L12 arrived from Sphere's today, fast shipping and very well
packaged, and it's in great condition considering it's maybe 40
years old. Thank you ever so much Walter.

Walter's diagnosis was spot on, there was a problem with the 1st
mixer, Tek 119-0130-00 which happens to be a RELCOM M11H-1. The
connectors look to be in good shape and a little pressure on the
rigid going into the mixer brings the mixer loss back up to what
it should be, give or take a few dBs perhaps, calibrator output
now shows up as -30dBm :-)

Good news, the diodes aren't fried but I suspect there is a dry
joint on the RF port (IF out) inside the mixer. I guess 40 years
of thermal cycling is going to produce a few dry joints here and
there.

I could either try to repair the dry joint or replace the mixer.

A repair would involve removing the case but I don't know what's
inside, so if anyone has ever taken one of these mixers apart a
picture or description would nice. If I could take it apart
without damaging anything I could always get a new case made.

The second option would be a drop in replacement. If anyone has
a datasheet for a RELCOM M11H-1 it would be greatly appreciated.

For now I will just have to gently prod a few rigid cables now
and then.

Best regards
Chris


Re: Tektronix Programmed Semiconductor Instruction Materials

Philip McIntosh
 

Yes that appears to be them. I corrected the link slightly to:

http://www.wa5jum.com/tutorialsarticles.htm

And there is a lot of interesting stuff there.

Thanks a lot.

Phil...

--- In TekScopes@yahoogroups.com, Dave Daniel <kc0wjn@...> wrote:

It's amazing what is available out there. Many people have gone to the
trouble of preserving these types of documents.

It always amuses me to find an item on eBay that one can down load for
free, paticulkarly when the item on eBay is only on digital media.

Dave


On 3/22/2013 6:45 PM, Tom Jobe wrote:

Thanks Dave!
I downloaded that whole series of free Tektronix Semiconductor books
from your link and they are very nice!
There is a lot of other good stuff on that web site too.
It is amazing how much good, freely available, stuff is for sale on eBay!
tom jobe...


Re: Tektronix Programmed Semiconductor Instruction Materials

Dave Daniel
 

It's amazing what is available out there. Many people have gone to the trouble of preserving these types of documents.

It always amuses me to find an item on eBay that one can down load for free, paticulkarly when the item on eBay is only on digital media.

Dave


On 3/22/2013 6:45 PM, Tom Jobe wrote:
 

Thanks Dave!
I downloaded that whole series of free Tektronix Semiconductor books from your link and they are very nice!
There is a lot of other good stuff on that web site too.
It is amazing how much good, freely available, stuff is for sale on eBay!
tom jobe...
 
 
 
----- Original Message -----
Sent: Friday, March 22, 2013 5:23 PM
Subject: Re: [TekScopes] Re: Tektronix Programmed Semiconductor Instruction Materials

 

Looks like these are available in PDF form at http://www.wa5jum.com/tutorialsarticles.htm, along with some other cool stuff.

DaveD


On 3/22/2013 5:30 PM, Tom Jobe wrote:
 
I saw the earlier post about this series of books from Tektronix.
I have an original copy of the volume titled "Semiconductor Diodes and Transistors programmed Instruction Volume 7, reference for Volumes 4 and 5". It has part number 062-0432-00 on the front of it and it is dated March of 1969. Obviously there are a number of other volumes in this series.
If there isn't a free copy of this volume available, I will be happy to scan its 227(?) pages into a PDF file and post it to KO4BB.com.
tom jobe...
 
 
 
 
 
----- Original Message -----
Sent: Friday, March 22, 2013 3:31 PM
Subject: [TekScopes] Re: Tektronix Programmed Semiconductor Instruction Materials

 

The vendor is Larry Christopher; I have purchased items from him over the last 3 years and

have found him to be a reliable and honest seller and also believe he is a member of this group.

Best Regards,

Chuck  w8dux

Aka rubbrdux




Re: Handy hint for a screen filter

keithostertag <keitho@...>
 

I don't know if it is still true, but years ago Rosco would send you, free, little sample books with 1x3 inch samples of all their gels in the mail. If they still do that, you could use the samples to test out which one works for your situation. You might look them up on the web to see if they still send out those free sample books. If you have a friendly local photo store nearby they might have them to hand out as well.

There might also be other sources as well- I haven't looked in to it for years. There are other brands- Rosco being one of the top- which means greater selection and generally slightly higher pricing.

Keith Ostertag


Re: Tektronix Programmed Semiconductor Instruction Materials

Tom Jobe <tomjobe@...>
 

Thanks Dave!
I downloaded that whole series of free Tektronix Semiconductor books from your link and they are very nice!
There is a lot of other good stuff on that web site too.
It is amazing how much good, freely available, stuff is for sale on eBay!
tom jobe...
 
 
 

----- Original Message -----
Sent: Friday, March 22, 2013 5:23 PM
Subject: Re: [TekScopes] Re: Tektronix Programmed Semiconductor Instruction Materials

 

Looks like these are available in PDF form at http://www.wa5jum.com/tutorialsarticles.htm, along with some other cool stuff.

DaveD


On 3/22/2013 5:30 PM, Tom Jobe wrote:
 

I saw the earlier post about this series of books from Tektronix.
I have an original copy of the volume titled "Semiconductor Diodes and Transistors programmed Instruction Volume 7, reference for Volumes 4 and 5". It has part number 062-0432-00 on the front of it and it is dated March of 1969. Obviously there are a number of other volumes in this series.
If there isn't a free copy of this volume available, I will be happy to scan its 227(?) pages into a PDF file and post it to KO4BB.com.
tom jobe...
 
 
 
 
 
----- Original Message -----
Sent: Friday, March 22, 2013 3:31 PM
Subject: [TekScopes] Re: Tektronix Programmed Semiconductor Instruction Materials

 

The vendor is Larry Christopher; I have purchased items from him over the last 3 years and

have found him to be a reliable and honest seller and also believe he is a member of this group.

Best Regards,

Chuck  w8dux

Aka rubbrdux



Re: Tektronix Programmed Semiconductor Instruction Materials

 

I believe the VintageTEK Museum (www.vintagetek.org) is in the process of scanning ALL of the Tek Programmed Instruction Series. This includes the Basic Electrical Theory, Semiconductor Diodes and Transistors, Time Domain Reflectrometry, and Spectrum Analysis volumes.

 

If any of you are in the Portland area it is definitely worth a visit to the museum. Their collection is growing by leaps and bounds and they are now selling excess (Tek and other) equipment at reasonable prices on their web site.

 

Volunteers are needed, and I speak from firsthand experience that as a volunteer you will meet some of the legendary designers at Tek.

 

Dennis


Re: 7854 waveform calculator on eBay

Chris Leyson
 

Not in any hurry to sell my 7854 or keyboard, paid about $500
for it 10 years ago, and then a lot on top of that to ship it
to the UK. They're great scopes and mine's outlived a 465 and
a 475.

I saw one 7L5 going for $1600 recently and another 7L5 going
for $2200. YOu could probably get a 3585 for that !!

Chris

--- In TekScopes@yahoogroups.com, Peter Gottlieb <hpnpilot@...> wrote:

Wow if that's what they're going for maybe I should sell my 7854 and keyboard
separately!

I am getting around to selling that and some others off, and it's a nice, fully
working unit, which seems to be getting rarer and rarer.

Didn't get it for $125 though...



On 3/22/2013 7:08 PM, d.seiter@... wrote:

I 'm surprised at how much these go for, considering it's basically just a
keyboard. I remember back in the late '70s when the local computer store was
selling keyboards for about $150. A few years later they became a cheap
commodity.

My entire 7854 system (except for the 7b87) cost me $125.

-dave

--------------------------------------------------------------------------------

*From: *"David Holland" <david.w.holland@...>
*To: *TekScopes@yahoogroups.com
*Sent: *Friday, March 22, 2013 12:52:28 PM
*Subject: *Re: [TekScopes] 7854 waveform calculator on eBay

IIRC, there's little aluminum pegs/stand offs that the circuit board
mounts on. They seem to like to break off if the keyboard gets
dropped, or otherwise knocked around.

I believe they'd reattach well enough with epoxy if enough of them got
broken for it to be an issue.

There's a few broken in mine, but not enough to be an issue.

On Fri, Mar 22, 2013 at 2:59 PM, Craig Sawyers
<c.sawyers@... <mailto:c.sawyers%40tech-enterprise.com>> wrote:
==================
I don't know. But I never assume something works when I buy it on eBay. It
does have circuitry in it which could fail.
==================

Yeah - but the circuitry is trivial. Four 74LSxxx chips, current
production, less than $2 for all four.

I was more worried about hardware things, like duff switches.

Craig



------------------------------------

Yahoo! Groups Links



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Re: Curve Tracer Test Temperature, Was Wanted: 7CT1N Curve Tracer Plug-In

Gordon <tekscopes@...>
 

On 22/03/2013 23:03, David wrote:
I think you could still do it with a curve tracer that does not
support storage by watching for the trace shift with temperature and
adjusting the FET bias point to minimize it.
I wasn't after the optimal bias/temp point, Dennis brought that up. I just wanted to measure Idss and get the same result whatever the ambient temperature was. And preferably in line with the manufacturers data.

[...] Look up "delta Vbe temperature" on Google.
AN45 to save anyone looking. Very interesting.

Thanks.

Gordon


Re: Curve Tracer Test Temperature, Was Wanted: 7CT1N Curve Tracer Plug-In

 

The important consideration for the 7CT1N and 5CT1N is cost, not capability.
No one at Tek thought that these two units were ever a substitute for a full
function curve tracer.

A 5CT1N and a 5000 series scope was the cheapest Tek curve tracer you could
buy, and if all you needed was a family of curves, it was a reasonable
solution.

Likewise, if your company already owned a 7000 MF, as most did, a 7CT1N was
the cheapest way to add curve tracer capability.

Many engineers are uncomfortable with the 575/576/577 because they don't use
them often enough. For those engineers the 5CT1N / 7CT1N must have been
easier to deal with.

If what I saw in my career is any indication most engineers don't know how
to use more than 1% of all the things a curve tracer can do for them. The
575 taught me more semiconductor theory than all of my college professors
combined. With my 577 I continue to learn new things that curve tracers can
do with all sorts of active and passive devices. I still don't think I have
used more than 40% of what it can do.

Dennis

-----Original Message-----
From: David
Sent: Friday, March 22, 2013 4:03 PM

On Fri, 22 Mar 2013 19:48:14 +0000, Gordon <tekscopes@mgcsoft.com>
wrote:

<snip>

I agree with Walter's earlier post that the 7CT1N is a lessor curve tracer.
I believe its popularity just comes from being a 7000 series plug-in. If
the 5000 series had been more popular than the 7000 series, then Walter from
Sphere would have said something about how overrated the 5CT1 is instead. :)


Re: Tektronix Programmed Semiconductor Instruction Materials

Dave Daniel
 

Looks like these are available in PDF form at http://www.wa5jum.com/tutorialsarticles.htm, along with some other cool stuff.

DaveD


On 3/22/2013 5:30 PM, Tom Jobe wrote:
 

I saw the earlier post about this series of books from Tektronix.
I have an original copy of the volume titled "Semiconductor Diodes and Transistors programmed Instruction Volume 7, reference for Volumes 4 and 5". It has part number 062-0432-00 on the front of it and it is dated March of 1969. Obviously there are a number of other volumes in this series.
If there isn't a free copy of this volume available, I will be happy to scan its 227(?) pages into a PDF file and post it to KO4BB.com.
tom jobe...
 
 
 
 
 
----- Original Message -----
Sent: Friday, March 22, 2013 3:31 PM
Subject: [TekScopes] Re: Tektronix Programmed Semiconductor Instruction Materials

 

The vendor is Larry Christopher; I have purchased items from him over the last 3 years and

have found him to be a reliable and honest seller and also believe he is a member of this group.

Best Regards,

Chuck  w8dux

Aka rubbrdux



Re: Tektronix Programmed Semiconductor Instruction Materials

Tom Jobe <tomjobe@...>
 

I saw the earlier post about this series of books from Tektronix.
I have an original copy of the volume titled "Semiconductor Diodes and Transistors programmed Instruction Volume 7, reference for Volumes 4 and 5". It has part number 062-0432-00 on the front of it and it is dated March of 1969. Obviously there are a number of other volumes in this series.
If there isn't a free copy of this volume available, I will be happy to scan its 227(?) pages into a PDF file and post it to KO4BB.com.
tom jobe...
 
 
 
 
 

----- Original Message -----
Sent: Friday, March 22, 2013 3:31 PM
Subject: [TekScopes] Re: Tektronix Programmed Semiconductor Instruction Materials

 

The vendor is Larry Christopher; I have purchased items from him over the last 3 years and

have found him to be a reliable and honest seller and also believe he is a member of this group.

Best Regards,

Chuck  w8dux

Aka rubbrdux

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