开云体育

I was in high school in the early '60s. I recall making several trips to a surplus store in Boston (don't remember the name) to gather parts for my senior science fair project. The most memorable component was a 4" CRT. I don't exactly remember what the project was, something to do with tracking thunderstorms, but it was good enough to get me into the state finals at MIT and earned me a certificate from NASA.

There was also Electro-Craft on Dorchester Ave (in Dorchester).
Tons of NIB ARC-5 Receivers and Transmitters.

73, Dick, W1KSZ
"Dahchester" Boy, 1940-1966
________________________________
From: [email protected] <[email protected]> on behalf of Brad Thompson <brad.thompsonaa1ip@...>
Sent: Monday, November 30, 2020 2:13 PM
To: [email protected] <[email protected]>
Subject: OT: Boston-area electronicsurplus (was:Re: [TekScopes] Fair Radio Sales Lima Ohio)

tekscopegroup@... wrote on 11/30/2020 12:28 PM:

I recall walking Canal Street in lower Manhattan in 1976 during a vacation trip with my parents.

<snip>
Hello--
Sometime in the early 1960 , my roommate and I hitchhiked from Boston to
his home near Suffern, NY-- his goal was to see his girl friend, and my
goal was
to visit Radio Row in NYC. I didn't have much spare cash and I don't
recall buying
anything <:. I do recall visiting Barry Radio at 512 Broadway, IIRC.
Construction
of the World Trade Center was on the horizon and the surplus stores were
beginning to close.

Fast-forward to the late 1960s-- I had graduated from college and had a
job in
Bedford, MA and a little more spare cash. On a typical Saturday, I could
drive
into Cambridge and visit Heffron's surplus junk yard. From there, I'd
head north to Rte. 128 and stop in Wakefield to shop at Poly-Paks ("We
bot <sic> thousands,
no time to test!") (*)

From there, Meshna's surplus in Lynn was always worth a stop, and on
one occasion
I was invited to visit the warehouse's basement-- filled with
boxes of surplus stacked from floor to ceiling and threaded
with shoulder-wide paths (think, 'mouse trails through a meadow').

There's still gas in the tank and cash in my wallet, and B+F Electronics
near Salem (?)
was my next stop. (B + F were Pete (?) Boniface and Frank Fink).

Finally, there was a four-story brick warehouse near Newburyport. MA,
which wouldstill had glass in most of its windows. On one occasion,
I reached into a box of miscellaneous parts and pulled out a skinny white
cylindrical object. Closer investigation revealed the remainder of the
pigeon skeleton.

Time to go home.

There were a few conventional electronics shops that sometimes offered
surplus
parts-- Abbott Electronics in Woburn, and a shop that moved into Malden
from Atlantic Avenue in downtown Boston. Radio Shack's store on Commonwealth
Avenue could offer an occasional bargain.

Further out in the suburbs, You-Do-It electronics sold little in the way
of surplus
but was the go-to site for unmolested components. Herbert Gordon (W1IBY
(SK))
sold used ham gear and surplus in Harvard, MA, and offered opinions.

I apologize for omissions and errors of location-- fifty years of recall
imposes a layer of haze on some memories.

73--

Brad AA1IP

(*) In practice, it was possible to buy functional components there, but
sorting through a batch of Transitron rejects and testing them
was very educational.

tekscopegroup@... wrote on 11/30/2020 12:28 PM:

I recall walking Canal Street in lower Manhattan in 1976 during a vacation trip with my parents.

<snip>
Hello--
Sometime in the early 1960 , my roommate and I hitchhiked from Boston to
his home near Suffern, NY-- his goal was to see his girl friend, and my goal was
to visit Radio Row in NYC. I didn't have much spare cash and I don't recall buying
anything <:. I do recall visiting Barry Radio at 512 Broadway, IIRC. Construction
of the World Trade Center was on the horizon and the surplus stores were
beginning to close.

Fast-forward to the late 1960s-- I had graduated from college and had a job in
Bedford, MA and a little more spare cash. On a typical Saturday, I could drive
into Cambridge and visit Heffron's surplus junk yard. From there, I'd
head north to Rte. 128 and stop in Wakefield to shop at Poly-Paks ("We bot <sic> thousands,
no time to test!") (*)

From there, Meshna's surplus in Lynn? was always worth a stop, and on one occasion
I was invited to visit the warehouse's basement-- filled with
boxes of surplus stacked from floor to ceiling and threaded
with shoulder-wide paths (think, 'mouse trails through a meadow').

There's still gas in the tank and cash in my wallet, and B+F Electronics near Salem (?)
was my next stop. (B + F were Pete (?) Boniface and Frank Fink).

Finally, there was a four-story brick warehouse near Newburyport. MA,
which wouldstill had glass in most of its windows. On one occasion,
I reached into a box of miscellaneous parts and pulled out a skinny white
cylindrical object. Closer investigation revealed the remainder of the
pigeon skeleton.

Time to go home.

There were a few conventional electronics shops that sometimes offered surplus
parts-- Abbott Electronics in Woburn, and a shop that moved into Malden
from Atlantic Avenue in downtown Boston. Radio Shack's store on Commonwealth
Avenue could offer an occasional bargain.

Further out in the suburbs, You-Do-It electronics sold little in the way of surplus
but was the go-to site for unmolested components. Herbert Gordon (W1IBY (SK))
sold used ham gear and surplus in Harvard, MA, and offered opinions.

I apologize for omissions and errors of location-- fifty years of recall
imposes a layer of haze on some memories.

73--

Brad? AA1IP

(*) In practice, it was possible to buy functional components there, but
sorting through a batch of Transitron rejects and testing them
was very educational.

On 2020-11-30 3:15 p.m., stevenhorii wrote:

Well, there were people called "computers". If you've seen the film "Hidden
Figures" the women who did the various calculations of orbital parameters
and trajectories were referred to as "computers" though a little-used term
for people who did computations was a "computor". No doubt that humans have
"stored programs".

You could argue that the patchboard used in analog computers was a
"program"

I like the definition Bruce cited because it would include such things.

but analog computers did not have Boolean logic (so far as I know
- maybe some of the digital/analog hybrids allowed for that). If anyone
knows of an analog computer that had a way of programming an "IF...THEN"
type of instruction, I would like to know about it. I think some of the
analog music synthesizers could sort of do this - a voltage-controlled
oscillator that could change the input and output of other analog
processing stages.

Composition of that sort is the entire basis of analog computing. Analog
comparators and switches (and multiplexers) have been known since valve
days, and are documented analog computer functions.

--Toby

I have also seen some analog computer modules (I don't

recall the manufacturer, but they were usually built around a single vacuum
tube) with unusual names, my favorite being a "Chaostron". I have no idea
what it did.

Steve H.

On Mon, Nov 30, 2020 at 12:47 PM Harvey White <madyn@...>
wrote:

IIRC, analog computers predated digital computers, and may well have
been simply (and firstly) called computers (with anything else called a
calculator).

People redefine terms based on what they know at the time, often
ignoring history. How many "analog" computers are on the market currently?

Hence, we "define" a computer as a device with a stored program.
Everyone forgets the "digital" part.

Look at the missile tracking and gun aiming aparatus from WWII, analog
servos, differential synchros, etc.

All performed mathematical (and often quite complex) functions involving
differential equations.

Hmmm.... takes a digital computer for that.......

And no, to answer the question, one typically qualified the word
"computer" with the word "analog" if it were one, back in the days when
analog computers roamed the earth.

See if you can find the SF novel "Venus Equilateral" by George O.
Smith. Pay attention to the electronics and computing part if you
would, which shows (amongst other things) mechanical tracking
"computers" using precisely machined and lapped cams. No digital
involved, IIRC.

Harvey


On 11/30/2020 12:05 PM, greenboxmaven via groups.io wrote:

The subject of analog computers has brought a few thoughts forward. I
remember them being offered in the classified ad sections of many
magazines decades ago, and Heathkit offered a notable one. General
Electric offered one in their basic experimenter's kits they sold in
the early 1960s. Did anyone question the name of "computer" for these
devices, instead of calculator, or analyzer? One definition I have
heard and embrace is "a computer is a control or calculating apperatus
with a stored operating program". I'm not trying to start a
semantics dispute, but do wonder if the word "computer" has been
applied at times for it's "Gee! Whiz!- It's a thinking machine! "
meaning to much of the public.

Bruce Gentry KA2IVY





On 11/30/20 11:09 AM, tekscopegroup@... wrote:

Electronic Experimenters Handbook Winter 1974:
Build the Bouncing Ball Analog Computer

Probably the old equipment was designed to be insensitive to exact values of carbon comp resistors.? Kudos to the designers for robust designs.Jim Ford?Sent from my Verizon, Samsung Galaxy smartphone

Yeah, the "tap-dance of relays adjusting circuits" still occurs these days, for example in spectrum analyzers doing auto alignments.? They sense when you're in the middle of a critical measurement and start flippping the relays right then!Jim Ford?Sent from my Verizon, Samsung Galaxy smartphone

Ed,

Thanks for the suggestions! I will dig a bit further into the box when I
can get to it - it's sitting behind several large boxes of stuff.

Steve H.

On Mon, Nov 30, 2020 at 3:42 PM Ed Breya via groups.io <edbreya=
[email protected]> wrote:

Steve, the digital circuitry in the bigger Comdyna box could be there for
a number of reasons. By the end of the analog computer era, digital stuff -
computing and otherwise - had already been around for a long time, so it
was natural to combine them and get the synergy of both technologies.
Lacking any documentation, you may be able to at least tell kind of what
the extra stuff was for, by studying the types of parts included, and doing
a little reverse engineering to see what things go back and forth between
sections. Here are a few thoughts on what it could be:

1. Digital readout of values. In the old days, it took quite a lot of
circuitry to build a DVM - even a whole board full of stuff, for say a four
digit A-D converter, and more stuff to select which signals to look at,
etc. The digital results of old-time DVMs were often provided to external
equipment such as digital computers for further processing, storage, and
printout. These were parallel interfaces, with four bits per digit, plus
possibly range and polarity info, and handshake lines. Also, sometimes the
computer could control the DVM's ranges. If there's quite a large (pin
count) interface connector/port on there somewhere, this could be a
possibility.

2. Digital storage/equivalent time conversion for display. One of the same
reasons as today. Digitizing the X-Y or T-Y signals could save and display
the results of a very slow compute cycle, or present flicker-free display
of a medium speed repetitive cycle.

3. Function generator. This is not the kind typically pictured when we
hear the name today, that generates CW square, triangle, and sine waves. In
the olden days there were all sorts of schemes to include multiplying and
dividing, and nonlinear and transcendental functions in analog computers,
from mechanical servos and cams, to semiconductor device characteristics,
to stepped diode (even tube diodes!) line/curve fit approximations. Then
there were special analog hybrids and ICs that could do log amps, and more
complicated combinations for all sorts of functions. All this can be done
discretely, but ICs greatly simplified it.

With the availability of more digital stuff like DACs, ADCs, and ROMs, it
became possible to make an arbitrary function generator. A tracking ADC
follows an analog input signal, and its result addresses a ROM, which is
programmed for various functions. The ROM data out drives the DAC,
resulting in the desired analog function response output.

I vaguely recall seeing info about this kind of FG for analog computers,
but not necessarily related to Comdyna. I think by this time, the digital
computers were common enough and capable enough to leave analog ones in the
dust. The look-up table method is of course commonly used today for AWGs
and such. I think that every modern DDS chip has buried somewhere inside, a
quarter-sine ROM table and DAC to produce the desired sine output.

If the Comdyna box has no microprocessor, but one or more ROMs, and ADCs
or DACs, then it could be a digital function generator.

4. The last category is one where a digital computer was used to set up an
analog computer - anything from the overall layout, to initial conditions,
to timing control. The analog computer would then do its thing, effectively
and relatively quickly, then the results would be digitized and read back
to the digital computer. This seems crazy today, but there was a time when
early digital just didn't have the compute power or memory, and an analog
one could be used as a peripheral device to make it easier - like a math
co-processor or DSP chip.

If the Comdyna box has lots of relays or JFETs (set up as signal
switches), or lots of more modern IC analog switches, then it could be for
remote control/peripheral use, or pre-programed setups. I do vaguely recall
some Comdyna literature about something like this.

Ed

Steve, the digital circuitry in the bigger Comdyna box could be there for a number of reasons. By the end of the analog computer era, digital stuff - computing and otherwise - had already been around for a long time, so it was natural to combine them and get the synergy of both technologies. Lacking any documentation, you may be able to at least tell kind of what the extra stuff was for, by studying the types of parts included, and doing a little reverse engineering to see what things go back and forth between sections. Here are a few thoughts on what it could be:

1. Digital readout of values. In the old days, it took quite a lot of circuitry to build a DVM - even a whole board full of stuff, for say a four digit A-D converter, and more stuff to select which signals to look at, etc. The digital results of old-time DVMs were often provided to external equipment such as digital computers for further processing, storage, and printout. These were parallel interfaces, with four bits per digit, plus possibly range and polarity info, and handshake lines. Also, sometimes the computer could control the DVM's ranges. If there's quite a large (pin count) interface connector/port on there somewhere, this could be a possibility.

2. Digital storage/equivalent time conversion for display. One of the same reasons as today. Digitizing the X-Y or T-Y signals could save and display the results of a very slow compute cycle, or present flicker-free display of a medium speed repetitive cycle.

3. Function generator. This is not the kind typically pictured when we hear the name today, that generates CW square, triangle, and sine waves. In the olden days there were all sorts of schemes to include multiplying and dividing, and nonlinear and transcendental functions in analog computers, from mechanical servos and cams, to semiconductor device characteristics, to stepped diode (even tube diodes!) line/curve fit approximations. Then there were special analog hybrids and ICs that could do log amps, and more complicated combinations for all sorts of functions. All this can be done discretely, but ICs greatly simplified it.

With the availability of more digital stuff like DACs, ADCs, and ROMs, it became possible to make an arbitrary function generator. A tracking ADC follows an analog input signal, and its result addresses a ROM, which is programmed for various functions. The ROM data out drives the DAC, resulting in the desired analog function response output.

I vaguely recall seeing info about this kind of FG for analog computers, but not necessarily related to Comdyna. I think by this time, the digital computers were common enough and capable enough to leave analog ones in the dust. The look-up table method is of course commonly used today for AWGs and such. I think that every modern DDS chip has buried somewhere inside, a quarter-sine ROM table and DAC to produce the desired sine output.

If the Comdyna box has no microprocessor, but one or more ROMs, and ADCs or DACs, then it could be a digital function generator.

4. The last category is one where a digital computer was used to set up an analog computer - anything from the overall layout, to initial conditions, to timing control. The analog computer would then do its thing, effectively and relatively quickly, then the results would be digitized and read back to the digital computer. This seems crazy today, but there was a time when early digital just didn't have the compute power or memory, and an analog one could be used as a peripheral device to make it easier - like a math co-processor or DSP chip.

If the Comdyna box has lots of relays or JFETs (set up as signal switches), or lots of more modern IC analog switches, then it could be for remote control/peripheral use, or pre-programed setups. I do vaguely recall some Comdyna literature about something like this.

Ed

You could always send the payment as a purchase and add the 3% PayPal fee if Dennis will allow that....

Well, there were people called "computers". If you've seen the film "Hidden
Figures" the women who did the various calculations of orbital parameters
and trajectories were referred to as "computers" though a little-used term
for people who did computations was a "computor". No doubt that humans have
"stored programs".

You could argue that the patchboard used in analog computers was a
"program" but analog computers did not have Boolean logic (so far as I know
- maybe some of the digital/analog hybrids allowed for that). If anyone
knows of an analog computer that had a way of programming an "IF...THEN"
type of instruction, I would like to know about it. I think some of the
analog music synthesizers could sort of do this - a voltage-controlled
oscillator that could change the input and output of other analog
processing stages. I have also seen some analog computer modules (I don't
recall the manufacturer, but they were usually built around a single vacuum
tube) with unusual names, my favorite being a "Chaostron". I have no idea
what it did.

Steve H.

On Mon, Nov 30, 2020 at 12:47 PM Harvey White <madyn@...>
wrote:

IIRC, analog computers predated digital computers, and may well have
been simply (and firstly) called computers (with anything else called a
calculator).

People redefine terms based on what they know at the time, often
ignoring history. How many "analog" computers are on the market currently?

Hence, we "define" a computer as a device with a stored program.
Everyone forgets the "digital" part.

Look at the missile tracking and gun aiming aparatus from WWII, analog
servos, differential synchros, etc.

All performed mathematical (and often quite complex) functions involving
differential equations.

Hmmm.... takes a digital computer for that.......

And no, to answer the question, one typically qualified the word
"computer" with the word "analog" if it were one, back in the days when
analog computers roamed the earth.

See if you can find the SF novel "Venus Equilateral" by George O.
Smith. Pay attention to the electronics and computing part if you
would, which shows (amongst other things) mechanical tracking
"computers" using precisely machined and lapped cams. No digital
involved, IIRC.

Harvey


On 11/30/2020 12:05 PM, greenboxmaven via groups.io wrote:

The subject of analog computers has brought a few thoughts forward. I
remember them being offered in the classified ad sections of many
magazines decades ago, and Heathkit offered a notable one. General
Electric offered one in their basic experimenter's kits they sold in
the early 1960s. Did anyone question the name of "computer" for these
devices, instead of calculator, or analyzer? One definition I have
heard and embrace is "a computer is a control or calculating apperatus
with a stored operating program". I'm not trying to start a
semantics dispute, but do wonder if the word "computer" has been
applied at times for it's "Gee! Whiz!- It's a thinking machine! "
meaning to much of the public.

Bruce Gentry KA2IVY





On 11/30/20 11:09 AM, tekscopegroup@... wrote:

Electronic Experimenters Handbook Winter 1974:
Build the Bouncing Ball Analog Computer

That's good information Menahem. Thanks for posting it.

I'll just add that I have a large number of 40-ish year old Allen
Bradley carbon comp resisters, many of them still in the factory sealed
packages. I have probed through the packaging and measured many of them and
they're ALL well out of spec! So don't trust old carbon camp resisters
even if they've never been used. Seeing how far out of spec that many of
these resisters are, it amazes me that any of this old equipment that uses
them still works!

Harvey White wrote...

"See if you can find the SF novel "Venus Equilateral" by George O. Smith.? Pay attention to the electronics and computing part if you would, which shows (amongst other things) mechanical tracking "computers" using precisely machined and lapped cams.? No digital involved, IIRC."

Hello--

IIRC, in a SF novel written by John W. Campbell, his protagonists are going somewhere in
a space ship and hear "...The tap-dance of relays adjusting circuits...."

Poetry, that.

73--

Brad? AA1IP

Sorry Dennis but I'm going to have to cancel my order for two copies of Peter's CRT book. I'm a LONG time Pay-Pal user but due to a combination of reasons; you, PayPal, and my credit union have made it impossible to pay for the books in the manner that you require. I frequently use PayPal to pay for purchases on E-bay, Amazon and other sites but those purchases are classified as Purchases and paid for through my credit card. It's not that I don't trust you but PayPal and my credit card will not allow me to make a payment to Friends or Family without the credit card company treating that as a cash advance and charging me a $30 fee! I tried to link my bank account to PayPal and transfer the money for the books from my bank account to PayPal and then to you but PayPal won't just accept my banking information. They require that I sign into my bank account via PayPal's website however PayPal and/or my credit union never complete that link so I am unable to transfer the money to PayPal and subsequently to you.

I appreciate your effort to make these books available but if the only payment method is via PayPal's Friends and Family, then I simply can't meet that condition. If you decide to accept money orders or even <gasp!> cash, let me know.

Joe Rigdon,
Florida

If you search through the Tektronix Common Design Parts catalog dated October 1982
()
you will find that these two parts have many part number gyrations. The -0367 is crossed over to a AST3571 which appears to be a custom 2N3571. Later in the catalog the part number SKA6516 appears. Also later on in the catalog you will see the
-0367 being selected and placed under a different Tek part numbers probably for use in other instruments.

The -0402 is used in the 7D15 and SG503 plus other units. The catalog crosses it over to a standard 2N3571 but later crosses it over to the AST3571 and then a SKA6814.

Confusing indeed. I’m assuming that the part number migration was probably due to ongoing revisions to the catalog.

Greg

From the past.....City College of New York, Terman Engineering bldg ...1964..1971:

Digital computer was an IBM 360, a huge room in the basement.
My last attempt at software keypunching Fortran II...printer as big as a Volkswagen and about as noisy...

The analog computing lab, had EAI with dozens (hundreds?) of Philbrick twin 12AX7 op amps and many meters and plotters. Huge patch panels to program.
Occupied the entire lab wall, required a dedicated air conditioner.

There was also an S plane plotter using electro graphic paper to make Bode or S plane plots.

I am an internet dinosaur....

Jon

Several years ago my wife and I were returning home from Florida through the panhandle.? We saw signs for the USS Alabama which is anchored in Mobile Bay and decided to detour and visit the ship. i heartily recommend for anyone with an interest in engineering or computers to tour any WWII battleship they can and pay particular attention to the "Gun Director" rooms which were located behind each of the main batteries.? While the main use for battleships in WWII was to place massive firepower on land targets to facilitate invasion, that is not what they were designed for!? They were designed to hit other battleships over the horizon and hence invisible while both ships were moving.? In addition to the obvious parameters which had to be considered, atmospheric conditions like temperature, barometric pressure and wind direction were also important.? The firing solutions were all determined and implemented through the use of mechanical computers and servos.? Once a firing solution had been generated, the ship could alter course and speed to become a more difficult target and the guns would still hit their mark!? While so much of today's computer programming consists of using commands and syntax in a language or operating system already in existence, just imagine what it would take to solve this problem with modern stuff and then considere doing so with an electromechanical system designed from scratch in the 1930's.? No Tektronix oscilloscopes were used on those ships or were injured in preparing this text!

Jack Reynolds

On Mon, Nov 30, 2020 at 11:29 AM Rogerio O <rodd414@...> wrote:

I was able to find the cause after a very careful inspection of the
solder joints around the newly replaced U2521.
There was a solder bridge between one pin and the shield trace.
Horizontal position back to life after the solder bridge was removed.

Good catch!
Shortly after I joined the group, someone here admonished me that when you
hear hooves, think horses before zebras. For me this means e.g. to look at
mechanical components before electronic components, but to always to
suspect my own work before another component failure :).

IIRC, analog computers predated digital computers, and may well have been simply (and firstly) called computers (with anything else called a calculator).

People redefine terms based on what they know at the time, often ignoring history.? How many "analog" computers are on the market currently?

Hence, we "define" a computer as a device with a stored program. Everyone forgets the "digital" part.

Look at the missile tracking and gun aiming aparatus from WWII, analog servos, differential synchros, etc.

All performed mathematical (and often quite complex) functions involving differential equations.

Hmmm.... takes a digital computer for that.......

And no, to answer the question, one typically qualified the word "computer" with the word "analog" if it were one, back in the days when analog computers roamed the earth.

See if you can find the SF novel "Venus Equilateral" by George O. Smith.? Pay attention to the electronics and computing part if you would, which shows (amongst other things) mechanical tracking "computers" using precisely machined and lapped cams.? No digital involved, IIRC.

Harvey

I recall walking Canal Street in lower Manhattan in 1976 during a vacation trip with my parents. It was store after store of surplus electronics. Better than a candy store!
Remember buying bunch of stuff, a 120v muffin fan with a slightly chipped fan blade, VU meters, some TO-3 devices and other stuff mounted on heatsinks, etc etc etc, and also a dirt cheap non working Cobra 132XLR radio which ended up having an open secondary in one of the IF transformers.

Did quite a bit of walking on my own during that trip, went on foot all the way from 57th from The Plaza where we where staying down to 32nd and 5th to a Radio Shack store. That was always a must do thing for me on any trips to the US to buy the little Archer components inside the individual color coded cardboard and plastic boxes that one could hang on a hook in the hobby room until needed. Plus all the other stuff I had to get for friends back home.

Excellent! Good Work.


--
Michael Lynch
Dardanelle, AR