Re: Risetime calculator (in tekwiki)

Hi Tim,
When I was in high school my friend and I built an analog computer with 2 pots and a meter. It multiplied two numbers together and displayed the result on the meter.
When we showed it to my friend's sister she asked us to multiply 2x3.
The result we got was around 8 on the meter. It could have been 9 or 7. It was hard to tell.
She was not impressed.

We looked around for something better to do with our budding career in electronics.
There wasn't much. The only "instrument" I owned was a VTVM. That limits your options.

Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Albert Otten
Sent: Friday, January 17, 2020 1:15 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Risetime calculator (in tekwiki)

Ideally you would use pots (as variable resistors) for which the resistance increases quadratically from ccw to cw. Then compare the sum of the first 3 resistances with the 4th resistance in a bridge circuit and tune the 4th pot to zero reading. I don't think that the quadratic behavior can be approached good enough with log pots and some trimpots and extra resistors.

Albert

On Fri, Jan 17, 2020 at 08:31 AM, Tim Phillips wrote:

from Tim P (UK)
What is this, please? It seems to be a simple analog computer, maybe
with Log pots.
In case the link doesn't work, the device is in tekwiki Other Instruments.

http://w140.com/tekwiki/wiki/Risetime_Calculator

Appears to give f = sqrt(a^2 + b^2 + c^2)

thanks
Tim P

--
Dennis Tillman W7PF
TekScopes Moderator

Re: 7A26 transient response 5 nS all atten

Chuck Harris <cfharris@...>

No letter, but starting with a "7" means it came from Tektronix Holland, NV,
Heerenveen, The Netherlands.

The last 5 digits of all of the serial numbers are sequential. I don't know
how they relate to the revisions of the manuals, and part changes, but I think
they are coordinated so that the revision ranges apply everywhere.

-Chuck Harris

Albert Otten wrote:

Hello Jon,
My other 7A26s have this format SN, but this has no letter, 708058. I think its a late model, but see no IC date codes.
Readout PCB is 672-0051-13 Amplifier PCB is 670-2549-21 attenuators are PN200-1442-00
The Readout board is probably marked 670-2310-09. Then both board versions were introduced at B251090. You need the -01 version manual for that, Revised SEP 1985. I think the ICs have 3-digit date codes, the first indicating the year (5xx pointing to 1985). Of course the plugin itself can be newer than the ICs in it. My 713121 is from 1986.
BTW did you mean 7904 or 7104?

Albert

Re: Risetime calculator (in tekwiki)

Tony Fleming

Thanks for sharing! You had a great job, despite stress and push to work
24/7 .... if the management could do that.
I wish I was working in a group like you did, the learning curve and new
"thinking" was a greatest teacher!
Have a great day!

On Fri, Jan 17, 2020 at 9:54 AM Dennis Tillman W7PF <dennis@ridesoft.com>
wrote:

Hi Tim,
It is an ANALOG computer. These were very commonly used for many things
but that was probably before you were born.
I got my first real job in 1967 working in a huge lab at Allied Aerospace
that designed airplane autopilots and flight control systems. Until a year
later these were always analog computers. To design the airplane's analog
flight control computer to have the right characteristics a team had to
measure the airplane's response to various (controlled) inputs such as how
it responded when commanded to make a sharp turn.

The job of the airplane's analog computer was to take that raw response
which was converted into an equation and create another equation that had
the response the customer (an airline) wanted. Presumably that would be to
turn the sharp bumpy turn into something gentle and smooth. This was all
done on a precision analog computer that had a plug board that was at least
6ft by 10ft long. Various modules (OpAmps, inductances, capacitances,
resistances, etc.) could be easily connected together and modified until
the engineers were satisfied with the results.

The final configuration was converted back into an equation and then a
different group of engineers took those equations and using OpAmp modules,
from companies like Philbrick Research, put it all together in a small box
that ultimately became the autopilot for that plane. By the time I arrived
Allied Aerospace was using newly developed OpAmp ICs such as the uA709. I
remember when I was only on the job for a few weeks and I blew one of those
uA709s out. I was really scared that I would be chewed out. Those things
cost \$50 each because they were so new. The OpAmp ICs revolutionized
everything we did. Suddenly the autopilot could be smaller and do more
things.

2 years later digital ICs were beginning to be reliable enough that they
could be used in parts of the autopilot. I worked on the Concorde Autopilot
that was done with this new family of DIGITAL logic called DTL. It had a
lot of details you had to be careful about like needing pull up resistors
in certain cases. Those caused trouble for a while. The problems were
solved eventually.
For a few years after that the autopilots were a mixture of analog and
digital ICs. Most of the autopilot was analog, and parts like VOTER
circuits, which decided which of the three autopilot results (everything is
triple redundant in an autopilot) is correct, were digital. This was done
with analog comparators and digital logic. If something should go bad with
one of the three autopilots the voter circuit disconnects it and relies on
the other two autopilot results.

Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Tim
Phillips
Sent: Thursday, January 16, 2020 11:32 PM
To: TekScopes@groups.io
Subject: [TekScopes] Risetime calculator (in tekwiki)

from Tim P (UK)
What is this, please? It seems to be a simple analog computer, maybe with
Log pots.
In case the link doesn't work, the device is in tekwiki Other Instruments.

http://w140.com/tekwiki/wiki/Risetime_Calculator

Appears to give f = sqrt(a^2 + b^2 + c^2)

thanks
Tim P

--
Dennis Tillman W7PF
TekScopes Moderator

Re: Risetime calculator (in tekwiki)

amirb

there are no opamps or any active device in this thing as far as I can tell. so no analog computer... See the picture...
only a bunch of resistors in some kind of bridge which must be balanced but why it will produce RMS beats me

On Fri, Jan 17, 2020 at 10:54 AM, Dennis Tillman W7PF wrote:

Hi Tim,
It is an ANALOG computer. These were very commonly used for many things but
that was probably before you were born.
I got my first real job in 1967 working in a huge lab at Allied Aerospace that
designed airplane autopilots and flight control systems. Until a year later
these were always analog computers. To design the airplane's analog flight
control computer to have the right characteristics a team had to measure the
airplane's response to various (controlled) inputs such as how it responded
when commanded to make a sharp turn.

The job of the airplane's analog computer was to take that raw response which
was converted into an equation and create another equation that had the
response the customer (an airline) wanted. Presumably that would be to turn
the sharp bumpy turn into something gentle and smooth. This was all done on a
precision analog computer that had a plug board that was at least 6ft by 10ft
long. Various modules (OpAmps, inductances, capacitances, resistances, etc.)
could be easily connected together and modified until the engineers were
satisfied with the results.

The final configuration was converted back into an equation and then a
different group of engineers took those equations and using OpAmp modules,
from companies like Philbrick Research, put it all together in a small box
that ultimately became the autopilot for that plane. By the time I arrived
Allied Aerospace was using newly developed OpAmp ICs such as the uA709. I
remember when I was only on the job for a few weeks and I blew one of those
uA709s out. I was really scared that I would be chewed out. Those things cost
\$50 each because they were so new. The OpAmp ICs revolutionized everything we
did. Suddenly the autopilot could be smaller and do more things.

2 years later digital ICs were beginning to be reliable enough that they could
be used in parts of the autopilot. I worked on the Concorde Autopilot that was
done with this new family of DIGITAL logic called DTL. It had a lot of details
you had to be careful about like needing pull up resistors in certain cases.
Those caused trouble for a while. The problems were solved eventually.
For a few years after that the autopilots were a mixture of analog and digital
ICs. Most of the autopilot was analog, and parts like VOTER circuits, which
decided which of the three autopilot results (everything is triple redundant
in an autopilot) is correct, were digital. This was done with analog
comparators and digital logic. If something should go bad with one of the
three autopilots the voter circuit disconnects it and relies on the other two
autopilot results.

Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Tim
Phillips
Sent: Thursday, January 16, 2020 11:32 PM
To: TekScopes@groups.io
Subject: [TekScopes] Risetime calculator (in tekwiki)

from Tim P (UK)
What is this, please? It seems to be a simple analog computer, maybe with Log
pots.
In case the link doesn't work, the device is in tekwiki Other Instruments.

http://w140.com/tekwiki/wiki/Risetime_Calculator

Appears to give f = sqrt(a^2 + b^2 + c^2)

thanks
Tim P

--
Dennis Tillman W7PF
TekScopes Moderator

Re: MEMBERS PLEASE READ: Our annual Group.io payment is due in 2 weeks.

It is groups.io obfuscating email addresses as has been explained many times already.

Dennis' email is dennis at ridesoft dot com

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Lawrance A. Schneider
Sent: 17 January 2020 14:43
To: TekScopes@groups.io
Subject: Re: [TekScopes] MEMBERS PLEASE READ: Our annual Group.io payment is due in 2 weeks.

Same happens to me.
further, what it the difference between @Dennis_Tillman_W&PF and the same thing in blue??? I saw a missive saying to use the above in blue and the same thing in black. I again tried each at PayPal and got the same thing asking for an :an error saying please enter valid email, name or mobile phone m=number.
I know I'm getting old, but what is going on???????

larry

Re: Risetime calculator (in tekwiki)

Hi Tim,
It is an ANALOG computer. These were very commonly used for many things but that was probably before you were born.
I got my first real job in 1967 working in a huge lab at Allied Aerospace that designed airplane autopilots and flight control systems. Until a year later these were always analog computers. To design the airplane's analog flight control computer to have the right characteristics a team had to measure the airplane's response to various (controlled) inputs such as how it responded when commanded to make a sharp turn.

The job of the airplane's analog computer was to take that raw response which was converted into an equation and create another equation that had the response the customer (an airline) wanted. Presumably that would be to turn the sharp bumpy turn into something gentle and smooth. This was all done on a precision analog computer that had a plug board that was at least 6ft by 10ft long. Various modules (OpAmps, inductances, capacitances, resistances, etc.) could be easily connected together and modified until the engineers were satisfied with the results.

The final configuration was converted back into an equation and then a different group of engineers took those equations and using OpAmp modules, from companies like Philbrick Research, put it all together in a small box that ultimately became the autopilot for that plane. By the time I arrived Allied Aerospace was using newly developed OpAmp ICs such as the uA709. I remember when I was only on the job for a few weeks and I blew one of those uA709s out. I was really scared that I would be chewed out. Those things cost \$50 each because they were so new. The OpAmp ICs revolutionized everything we did. Suddenly the autopilot could be smaller and do more things.

2 years later digital ICs were beginning to be reliable enough that they could be used in parts of the autopilot. I worked on the Concorde Autopilot that was done with this new family of DIGITAL logic called DTL. It had a lot of details you had to be careful about like needing pull up resistors in certain cases. Those caused trouble for a while. The problems were solved eventually.
For a few years after that the autopilots were a mixture of analog and digital ICs. Most of the autopilot was analog, and parts like VOTER circuits, which decided which of the three autopilot results (everything is triple redundant in an autopilot) is correct, were digital. This was done with analog comparators and digital logic. If something should go bad with one of the three autopilots the voter circuit disconnects it and relies on the other two autopilot results.

Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Tim Phillips
Sent: Thursday, January 16, 2020 11:32 PM
To: TekScopes@groups.io
Subject: [TekScopes] Risetime calculator (in tekwiki)

from Tim P (UK)
What is this, please? It seems to be a simple analog computer, maybe with Log pots.
In case the link doesn't work, the device is in tekwiki Other Instruments.

http://w140.com/tekwiki/wiki/Risetime_Calculator

Appears to give f = sqrt(a^2 + b^2 + c^2)

thanks
Tim P

--
Dennis Tillman W7PF
TekScopes Moderator

Re: 2445 EPROMs

Chuck Harris <cfharris@...>

Back in those days I was always and Intel guy.

Customers forced me to learn Motorola 6800 and 68000, but
it wasn't a labor of love, so I have forgotten almost
everything I ever knew about them.

And my data books for them are ...somewhere...

Thanks Mark!

Mark Litwack wrote:

Hi Chuck and Chris,

The external clock input on the 6802 is divided internally by four to create an internal two-phase clock (one phase is output as signal "E"). So, with a 5MHz input, the cycle time is actually 800ns, which well within range of the Intel D27128 with 250ns access time I mentioned before.

There is also the NOP exerciser which can be enabled with jumper P503. This is good for getting to the bottom of possible processor and/or bus buffer issues by looking at E, address lines, and other signals as the processor is looping. Its operation is described in the service manual.

I do recall one instance of a bad processor, but granted, they are rare.

-mark

Re: Tek 533 -150 test point

N7QL

Thank you very much! I appreciate it.

Re: Tektronix 532 LV rail shorted

randolphbeebe@...

Rajesh,

I have not had time to look at it again yet. Hopefully this weekend. One spot of good news is that I just checked the fuse and it was blown. That would sure account for no voltage at C640!

One thing that is curious however, upon reviewing the schematics of the LV power supply I read my notes and recalled that when I measured the voltage at pin 16 on the transformer it measured +89V AC. I do not expect to see the voltage near the correct numerical value on the crippled circuit but POSITIVE voltage? Would that account for the symptoms as well since both C640 and C110 are installed positive to ground?

Can that positive voltage be coming from one of the other supply rails perhaps, the +350, +225 or the +100? Or a fault in the transformer. It gives me something to think about when I read about the circuit description.

Your time distribution method is excellent, I am trying to get away from the neophyte's instinct to just shotgun parts to "see if it works now".

Randy

Re: MEMBERS PLEASE READ: Our annual Group.io payment is due in 2 weeks.

Lawrance A. Schneider

Next year is AN OTHER YEAR.
We will come to the same place as far as needing contributions.
Some succeeded and some did not (me).

So, what do we do next year. I very much enjoy this group! I would be happy to contribute!

HOW????

larry

Re: 7A26 transient response 5 nS all atten

Albert Otten

Hello Jon,
My other 7A26s have this format SN, but this has no letter, 708058. I think its a late model, but see no IC date codes.
Readout PCB is 672-0051-13 Amplifier PCB is 670-2549-21 attenuators are PN200-1442-00
The Readout board is probably marked 670-2310-09. Then both board versions were introduced at B251090. You need the -01 version manual for that, Revised SEP 1985. I think the ICs have 3-digit date codes, the first indicating the year (5xx pointing to 1985). Of course the plugin itself can be newer than the ICs in it. My 713121 is from 1986.
BTW did you mean 7904 or 7104?

Albert

Re: MEMBERS PLEASE READ: Our annual Group.io payment is due in 2 weeks.

Paul Amaranth

Email addresses are of the form

<ID> @ <Organization>

If it isn't in that form it's not an email address. Period.
Color has no meaning for email.

the public website is more difficult. This is a good thing as it
prevents some amount of spam.

I generally do not use the web interface, but I think the assumption
here is you would go to the member's profile and either get the
correct email address from there or send them a private message.

If you got the list as an email instead of looking at the website,
email addresses would be visible since they are not redacted.

I think groups.io did a really nice job with that.

Paul

On Fri, Jan 17, 2020 at 06:42:49AM -0800, Lawrance A. Schneider wrote:
Same happens to me.
further, what it the difference between @Dennis_Tillman_W&PF and the same thing in blue??? I saw a missive saying to use the above in blue and the same thing in black. I again tried each at PayPal and got the same thing asking for an :an error saying please enter valid email, name or mobile phone m=number.
I know I'm getting old, but what is going on???????

larry
--
Paul Amaranth, GCIH | Manchester MI, USA
Aurora Group of Michigan, LLC | Security, Systems & Software
paul@AuroraGrp.Com | Unix & Windows

Re: 2445 EPROMs

Mark Litwack

Hi Chuck and Chris,

The external clock input on the 6802 is divided internally by four to create an internal two-phase clock (one phase is output as signal "E"). So, with a 5MHz input, the cycle time is actually 800ns, which well within range of the Intel D27128 with 250ns access time I mentioned before.

There is also the NOP exerciser which can be enabled with jumper P503. This is good for getting to the bottom of possible processor and/or bus buffer issues by looking at E, address lines, and other signals as the processor is looping. Its operation is described in the service manual.

I do recall one instance of a bad processor, but granted, they are rare.

-mark

Re: MEMBERS PLEASE READ: Our annual Group.io payment is due in 2 weeks.

Lawrance A. Schneider

Same happens to me.
further, what it the difference between @Dennis_Tillman_W&PF and the same thing in blue??? I saw a missive saying to use the above in blue and the same thing in black. I again tried each at PayPal and got the same thing asking for an :an error saying please enter valid email, name or mobile phone m=number.
I know I'm getting old, but what is going on???????

larry

Re: 7A26 transient response 5 nS all atten

Jean-Paul

Colin! Many thanks, My manuals cover only B serials. Changes in Guernsey version?

All: My first reaction was calibration; page 5-7 sec 8, High Freq compensation.
But there are 10 adjustments per channel listed!
What order of adjustment? Which one might be for just the first 5-10 nS?

Mille mercis,

Jon

Re: Remote CSA803 / HP1180x programming (yet again)

GerryR <totalautomation1@...>

It must have been "Recommended Standard," because I had (have somewhere?) a book that had 132 or so versions of the RS-232 "standard" interface. That's a lot of versions of a so-called standard!
GerryR
KK4GER

----- Original Message -----
From: "Leo Bodnar" <leo@leobodnar.com>
To: <TekScopes@groups.io>
Sent: Friday, January 17, 2020 8:18 AM
Subject: Re: [TekScopes] Remote CSA803 / HP1180x programming (yet again)

What I really like about RS-232 is that RS stands for "Recommended Standard"!
Leo
On Fri, Jan 17, 2020 at 10:59 AM, Roy Morgan wrote:
Among my coworkers were the folks who organized and chaired the international committees that wrote the standards. (One fellow had chaired the committee that developed RS-232.)

Re: "liquid crystal driver" sighting

Glenn Little

I am currently working on drawing a schematic. Slow going. Hope to have it done and posted sometime in February.

Glenn

On 1/17/2020 3:04 AM, p mc wrote:
Thank you, Mr. Little, for starting to fill in a blank spot on the map.

At TekWiki I cleaned out the obsolete stub text and poor front panel image.

--
-----------------------------------------------------------------------
Glenn Little ARRL Technical Specialist QCWA LM 28417
Amateur Callsign: WB4UIV wb4uiv@arrl.net AMSAT LM 2178
QTH: Goose Creek, SC USA (EM92xx) USSVI LM NRA LM SBE ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"

Re: Looking for cabinet top for 465M

On 1/16/2020 7:29 PM, KB6NAX wrote:
I'll buy a junked 465M if it will go for cheap just to get a top cover. Just let me know. Thanks. -Ard
Where are you located?

Re: Remote CSA803 / HP1180x programming (yet again)

Leo Bodnar

What I really like about RS-232 is that RS stands for "Recommended Standard"!
Leo

On Fri, Jan 17, 2020 at 10:59 AM, Roy Morgan wrote:
Among my coworkers were the folks who organized and chaired the international committees that wrote the standards. (One fellow had chaired the committee that developed RS-232.)

Re: 7A26 transient response 5 nS all atten

Colin Herbert

Hi,
I, too, have a 7A26 with no letter at the front of the serial-number (102925). The label with this serial-number on it also identifies the plug-in as having been manufactured in Tektronix, Guernsey, which is why there is no "B" or "H" in front of the serial-number.
My manual, though originally produced in Beaverton (as I think all may have been), has a page in the "Change Information" section at the back referring to changes to Guernsey-produced 7A26s from tentative S/N 100396 and 100777.
I don't know how much use this will be to you, but I also have a source of the ICs used in the 7A26 (unless they have all been sold). They don't usually fail, but swapping them between channels (they are plug-in but be careful of bending the legs) is a pretty simple way of verifying them.
There are also a couple of resistors, one in each channel, which are at about their wattage limit, get hot and sometimes change value because of this. They are R1327 and R1329 (8K2, 0.25W. Carbon comp.) and would benefit in being replaced with resistors of higher wattage.
Colin.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Jean-Paul
Sent: 17 January 2020 12:20
To: TekScopes@groups.io
Subject: [TekScopes] 7A26 transient response 5 nS all atten

Hello all: My workhorse 7A26 needed rework, in 7804 mainframe.
Cleaned the AC/DC/GR contacts on attn with the iso alcohol-paper strips, and exercised some scratchy controls.
Poor fast transient response on CH2, same dip and peak ~ 5 nS at ALL V/div.

Setup: Leo Bodnar pulser 40 pS>Mini Ckt HAT-15>>Mini Ckt HAT 20>>precision 50 Ohm thru>>7A26 input
Same result if 7A26 is in L or R side 7804.
Shots are: Affected 7A26, CH2, CH1, Good 7A26 Ch2 Ch1
http://crypto-museum.org/TEK/7A26/7A26.pdf

Since the aberration is constant on every V/DIV, the attenuator and 2X amp seem to be exonerated.

Before I dare probe the CH 2 amp circuit, a few questions please:

1/ Test points mentioned on schematic are NOT in PCB photos, only the parts numbers. Need a board layout with test pts.
2/ Using normal P6137 probe. placement of ground lead ?
3/ Precautions in probing around the custom TEK hybrid ICs, eg U2350, U2450?
4/ Serial: Manual has sch versions for SN B179999 < and B180000>.
My other 7A26s have this format SN, but this has no letter, 708058. I think its a late model, but see no IC date codes.
Readout PCB is 672-0051-13 Amplifier PCB is 670-2549-21 attenuators are PN200-1442-00

Hope to receive some tips from our TEK veterans!

Jon in Paris

 18841 - 18860 of 182167