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Re: (OT) Where to go for 70s IBM hardware? I'm looking for a terminal.
Bill,
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A really good book on the history of inertial navigation and the impact it had - somewhat frightening in that improvements actually made the use of nuclear weapons easier to imagine on the part of military folks - is fascinating. It's called "Inventing Accuracy" by Donald MacKenzie. There is also an out-of-print series I would love to find - it came from the AGARD folks and is a history of gyroscopes. I have one volume, but I think there were three of them. I like mechanical gyros as well. The problems the engineers had to face - mostly to do with bearings and maximizing angular momentum while keeping the weight reasonable - tend to cross multiple engineering disciplines from metallurgy to materials science, not ignoring how to make the things and the electronics of picking off the signals. The amazing gyros to me are the gas-bearing ones. No metal bearings to wear out, though I wonder about dealing with the bearings before spin up (at least for the hydrodynamic bearings that need to spin to produce the film of gas that keeps the bearing surfaces from contacting each other). The G300 gyro from Litton had a gas bearing wheel. It's a beautiful gyroscope - almost all beryllium so manufacturing them must have been a challenge. Many were scrapped by surplus folks for the beryllium and the small gold alloy balance weights on the float assembly. They were very widely used - commercial aircraft (the Litton LTN-51) and numerous military aircraft. The one inertial instrument I would love to find is a gyro-accelerometer. These use an unbalanced gyro and the torque it generates with acceleration. I believe the Saturn V used them in the inertial platform. I think some of the later strategic missiles do as well - the MX/Peacekeeper comes to mind. I did set up one of the DC gyros - surplus from the Nike missile - to look at the output. Bringing this back to a Tek thread, the output of that gyro was a change in resistance. So putting the pickoff resistor in a simple circuit to change an output voltage from a power supply and I looked at the output on a Tek scope. If I recall, I did this with a 547 that I had. The gyro was a rate gyro. I don't have a rate table, but it was fun to twist the thing around and watch the scope trace out the rate it sensed. The gyros with the synchro outputs are more difficult to deal with. An engineer I was working with at the time went a little further - he sent my gyro circuit output to an opamp and then digitized that output with an A-D converter. More circuitry, but not as much fun as simply looking at the output in real-time on the scope. I was writing code in the days of punched cards (spent many hours at an IBM 026 and later, an 029 keypunch machine) and waiting for my output after submitting my card deck. FORTRAN on an IBM 7094. Later, I ran code on a PDP-8 and on a PDP-11. I used DEC Vax machines, but by that time, often just running my data on application software, not writing my own code. I spent hours at an ASR-33 teletype running timeshared stuff on a DECSystem 10. I don't miss punching cards or batch processing computer jobs, but it makes for great stories to share. My young colleagues regard some of those stories I am sure like we did when our parents told us about having to walk to school even when it snowed, writing homework longhand, and doing their math problems with pencil and paper. I tell the young folks that their smartphones are many times more powerful than the computer that got us to the moon. Steve H. On Fri, Nov 27, 2020 at 6:05 PM Bill E <solartron@...> wrote:
MEMS? Dang newfangled stuff. Give me rotating mass any time. :) The DC-10 |
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Re: (OT) Where to go for 70s IBM hardware? I'm looking for a terminal.
FWIW inertial navigation systems and GNSS (Global Navigation Satellite Systems) are complementary.? ?INS tend to drift over time, and GNSS provide corrections.? Navigation in GNSS-denied or -degraded areas is a whole other ballgame.Jim Ford??Sent from my Verizon, Samsung Galaxy smartphone
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-------- Original message --------From: stevenhorii <sonodocsch@...> Date: 11/27/20 1:04 PM (GMT-08:00) To: [email protected] Subject: Re: [TekScopes] (OT) Where to go for 70s IBM hardware? I'm looking for a terminal. Harvey and Bill,Yes - I've tried that trick. For small gyros it works. Gyros with electricspin motors tend to draw the most current at startup as do most motors.After that, the current usually drops quite a bit. Some of the 400Hz gyrosuse two-phase power. The usual trick is to put a capacitor across the twospin motor inputs - it provides the phase lag for the second phase. I haveNOT tried this, but I have seen some gyros - usually the small ones thatare about one-inch in diameter and three inches long and almost always rategyros - that had a phase-splitting capacitor already soldered in place.This white paper describes a basic 2-phase power supply for gyro spinmotors: was fortunate - at a hamfest years ago, I picked up a couple of AbbottTransistor Labs inverters. These took 24-28 VDC and output AC 400Hz singlephase at up to about 2 amps. Not enough to run a large gyro, but enough forthe smaller ones. I even ran a fairly large gyro - a Honeywell rate gyro -with one of these. They do need a heatsink.I sometimes do an eBay search for "Behlman Invertron" as they made somevery useful frequency converters - 115 VAC to variable 400Hz AC. Some werevariable frequency and some versions also had single to three-phase output.They tend to be expensive (and heavy for the higher output ones) and Inever managed to find one at what I thought was a reasonable price. Someversions had interchangeable plug-in oscillators so you could run evenhigher frequency AC devices (some gyros use 800 Hz - the Apollo programgyros ran with 800 Hz, 2-phase power). There are currently a couple ofBehlman Invertrons on eBay, though they are not cheap.If you can find them, some of the WW II and even early missile (Nike) gyrosran on DC (24-28 v). Those are fun to run up. However, I've had some forwhich the bearings almost certainly were bad - they were very noisy whenrunning and spin-down after power was removed was quite fast. Likely whythey were surplus.Years ago, a surplus dealer on Canal Street in NYC sold me a WW II Bendixvertical gyro. It was a 400Hz gyro and he told me I could run it on 60Hz ACby putting a current limiting incandescent lamp (no choices - there were noLED lamps then) in the power circuit and running at a lower voltage via aVariac. I did not have the guts to try it, but I do know those who did andsaid it works, but you will not get the gyro up to full speed.Messing about with gyros can lead you down a deep hole much as gettingfascinated by Tektronix equipment and then desiring to get some (plusspares "for parts" and all the manuals). Now you can get fairly accurategyros made using IC fab techniques - the MEMS units. These things live insmart phones and tablets now. These plus GPS have radically changedinertial navigation. Fun stuff, though.Steve H.On Fri, Nov 27, 2020 at 1:52 PM Harvey White <madyn@...> wrote:> Hi-fi amplifier of sufficient output capability driven by a sinewave> generator sitting at 400 Hz?>> Harvey>> On 11/27/2020 11:52 AM, Bill E wrote:> > Even though way off the off topic topic (parse that), still a fun> discussion. I scored a box of 10 real gyros and logic pulled from DC-10s.> Cute little rate gyro, etc. Problem is, all that stuff takes 28v 400Hz.> Haven't gotten around to making a power supply for them yet.> >> >> >> >> >> >>>> >>>
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Re: Resistor in series
Bob Albert wrote:
Here's an oral history video discussing the history of industrial design at Tek: The speaker is the former head of industrial design at Tek (Gale Morris) and he mentions (possibly hyperbolically) that the 453 sold 70,000 units in a single shot to IBM, so the pennies can really add up. -- Jeff Dutky |
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Different Versions of XYZs of Oscilloscopes
I have a copy of The XYZs of Oscilloscopes that appears to have come with an early 2213, but I have seen PDFs with the same title with much later copyright dates, and have seen similar for sale online.
My question is how many different versions were there of this book? The one I have discusses both the 2213 and 2215, but uses pictures of the 2213 in almost all the examples (except for one that illustrates the dual time base, which the 2213 doesn't have). Were there different versions of the book produced for the different scopes in 2200 series? Were there versions of the book for the 400 series scopes (or the 2400 series)? -- Jeff Dutky |
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Re: (OT) Where to go for 70s IBM hardware? I'm looking for a terminal.
MEMS? Dang newfangled stuff. Give me rotating mass any time. :) The DC-10 gyros I have (part of the fight stability system) are 2 phase, but have a phase-shift cap. I've managed to spin up a few using random hackery (old audio amp, TEK frequency synthesizer, some fets, not pretty). They are amazingly sensitive. Interestingly, if you're an INS nerd, the gyros are set up for strapdown, but they just run using an analog resolver. I have a breadboarded inverter I never finished because we were moving. Giving me incentive to pick that project up again. As for 'bad' bearings, frequently because of hardened lubrication. If you're daring, dismantle, use some new lube, all set to go.
Ok, to bring more back on topic, did Tek have any INS plugins for the TM500x frames? (of course not, but hey, I can dream) Bill PS - if this is going to be a continuing OT thread, maybe a name change? OTOH, I did use a lot of IBM hdw back in the '70s. IBM 1130, 360, 370, card punches, etc. Something I've managed to mostly forget. BALR! Also DEC 6, 8, 10, and 11. Spacewar on the 6 at the MIT AI lab, classic :) Even more so, Mazewar on the 10/Imlacs. I have an 8 replica running OS/8 and an 11 replica running RSX, with real blinking lights and switches, in my living room. Oh, and a random assortment of TMS plugins, and several 2465's, last of the truly great analog scopes. |
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Re: Resistor in series
Bob Albert
Les obvius is that the engineer had stock in a resistor company/? Sure, a resistor is only 2? but multiply that by 1000 and you get into some real money,
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On Friday, November 27, 2020, 02:50:13 PM PST, Dennis Tillman W7pF <dennis@...> wrote:
There is another explanation for doing something like this which is not as obvious. If you look at the schematic for the 067-0681-01 Tunnel Diode Pulse Generator designed by John Addis at Tektronix There are three 1/8W 1Kohm resistors (R4, R5, and R6) connected in series going to the tunnel diode. Several years ago I asked him why he did not use one 3Kohm resistor instead. What he knew and I learned was that the body capacitance of each of these 3 resistors in series was far less than the body capacitance of one 3Kohm resistor. The TD is being driven by the collector of the transistor which is high impedance, and the three 1Kohm resistors in series reduces the time constant of the pulse going to the Tunnel Diode without adding any additional capacitance across the Tunnel Diode that would slow it down. I doubt this had anything to do with Tek portable scopes since their frequency response is almost two orders of magnitude slower than the fast edge of the Tunnel Diode Pulse Generator but sometimes there are other explanations for why you might encounter things that are not obvious. Dennis Tillman W7pF -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Milan Trcka Sent: Tuesday, November 24, 2020 9:09 PM To: [email protected] Subject: Re: [TekScopes] Resistor in series Jeff, the resistors connected end to end are an attempt to make a required resistance that was not available as a standard resistor value. Shortage of parts? Engineering change? Select in test? Who knows. I have a few of those in my 453 scope. -- Dennis Tillman W7pF TekScopes Moderator |
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Re: Resistor in series
There is another explanation for doing something like this which is not as obvious.
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If you look at the schematic for the 067-0681-01 Tunnel Diode Pulse Generator designed by John Addis at Tektronix There are three 1/8W 1Kohm resistors (R4, R5, and R6) connected in series going to the tunnel diode. Several years ago I asked him why he did not use one 3Kohm resistor instead. What he knew and I learned was that the body capacitance of each of these 3 resistors in series was far less than the body capacitance of one 3Kohm resistor. The TD is being driven by the collector of the transistor which is high impedance, and the three 1Kohm resistors in series reduces the time constant of the pulse going to the Tunnel Diode without adding any additional capacitance across the Tunnel Diode that would slow it down. I doubt this had anything to do with Tek portable scopes since their frequency response is almost two orders of magnitude slower than the fast edge of the Tunnel Diode Pulse Generator but sometimes there are other explanations for why you might encounter things that are not obvious. Dennis Tillman W7pF -----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Milan Trcka Sent: Tuesday, November 24, 2020 9:09 PM To: [email protected] Subject: Re: [TekScopes] Resistor in series Jeff, the resistors connected end to end are an attempt to make a required resistance that was not available as a standard resistor value. Shortage of parts? Engineering change? Select in test? Who knows. I have a few of those in my 453 scope. -- Dennis Tillman W7pF TekScopes Moderator |
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Re: There is no good time to be SICK
Hey Denis,
Happy Turkey day and my best to Marian, I hope she gets her surgery soon. My daughter's skating coach has had both hips replaced and she's back on the ice at 75 years young. She tells us it's like reversing a couple of decades. BTW: I love Goldens, they just always seem to have this air of happiness and joy around them. IMHO they're second best to the Icelandic Sheepdog - here's our F¨¢lki helping out with a champagne afternoon social on our front porch: (my wife's workaround for COVID social distancing restrictions). Stay safe, and thanks for arranging the CRT book thang, hope you don't end up regretting it, Siggi On Fri, Nov 27, 2020 at 3:51 PM Dennis Tillman W7pF <dennis@...> wrote: My apologies. I sure my absence the past 4 days has caused some concern. I |
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Re: 528A TV waveform monitor.
I just took a quick look at the 528 on tekwiki. As it is, it's pretty much only good for the original purpose. But, it appears to have an electrostatic deflection CRT (since it's basically a scope, not a TV display, which would tend to use raster-scan), so you could convert it to a nice little low speed X-Y monitor, with simple changes to the guts, if you're so inclined, and need such a thing. I don't know if the graticule is built into the CRT face (probably) - if so, you'd be stuck with the IRE etc scales, instead of a nice grid. If you really want to fix and make it into an X-Y monitor, you can probably find some Tek scope or other CRT that is the same except for the faceplate, and swap it in.
Ed |
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Re: There is no good time to be SICK
Dennis,
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I am glad to hear that you are ok. I, for one, am in no hurry for you to send the book. I¡¯d prefer that you deal with the higher priority items on your list first. DaveD On Nov 27, 2020, at 15:51, Dennis Tillman W7pF <dennis@...> wrote: |
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Re: worst condition Tektronix scope?
Yes, I did. Also to Vintage Tek. I believe he reviewed many of the 7854
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comments as he was troubleshooting the scopes I gave him. I encouraged him to put up the replacement 454 rear feet for sale or maybe post the 3D print files to the group. Steve H. On Fri, Nov 27, 2020 at 4:17 PM Jim Ford <james.ford@...> wrote:
I hope you pointed him to TekScopes and TekWiki.Jim Ford Sent from my |
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Re: worst condition Tektronix scope?
I've looked in the catalogs for both HP and Tektronix.? I haven't seen any mention of a Tektronix Pope.
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Harvey (nor HP) Would one be used to look at the output of an old style Vatican Camera? H. On 11/27/2020 4:42 PM, Jeff Dutky wrote:
Richard Steedman wrote:Have you read the full description of this guy's scope?The color of the smoke is VERY important: it tells you whether or not we have a new Pope. |
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Re: 528A TV waveform monitor.
Various things still have NTSC type outputs.
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1) older video equipment, VCRs, TV cameras, some surveillance TV cameras. 2) many older video games that have a TV output. 3) Amateur Radio still uses NTSC video on 435 Mhz and up if you're interested. You can look at the outputs with this. Modern digital, some HD surveillance cameras, etc.? Nope, although it might be interesting to see what the scope can make of the signals.? I do have a 1910 digital pattern generator, and a pair of Hitachi scopes, NTSC and Vector.? Needless to say, I have some old video equipment around, one way or another.? Currently, all that is used are the older surveillance things.? When I was making TV cameras and playing with video, I'd have killed for some of this. Harvey On 11/27/2020 3:19 PM, Roy Thistle wrote:
Hi All: |
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Re: 528A TV waveform monitor.
Roy,
If you do any standard-definition TV (SDTV) work - such as converting older videocassette or other SDTV recordings to DVD, both a waveform monitor and vectorscope would be useful. A timebase corrector might also be helpful. All of this stuff can now be obtained at relatively low cost. But I don't know of non-SDTV uses for these items. It's too bad because they are great instruments. I had a Tektronix 1900 and then a 1910 TV signal generator. These had digital signal generation but converted to analog output for driving monitors and the like for testing. Tektronix had quite a product line to support the television industry. Tektronix equipment (along with Grass Valley Group which Tektronix acquired) was likely in almost every TV studio in the US. I think the huge 2" quad video machines came with a Tektronix waveform monitor and vector monitor installed in them, at least the vintage RCA and Ampex ones I have seen did. There must be some collectors or users of SDTV stuff out there. I have seen prices of the old Sony U-Matic machines (the studio ones) sell for higher prices than one would expect (the broadcast version of the Sony U-Matic machine - the BVU-950 - sells for over $2000). Even the Sony BVH-3100 one-inch C-format machines sell for over $1000 (on eBay) and shipping for these things would be a quarter to half of that cost. Steve H. On Fri, Nov 27, 2020 at 3:19 PM Roy Thistle <roy.thistle@...> wrote: Hi All: |
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Re: worst condition Tektronix scope?
Richard Steedman wrote:
The color of the smoke is VERY important: it tells you whether or not we have a new Pope. -- Jeff Dutky |
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Re: There is no good time to be SICK
Dennis,
I am glad you recovered and were able to enjoy Thanksgiving food. My wife and I stayed home as well but we did a Zoom get-together with family. Not as much fun as an in-person event, but better than complete isolation and a lot better than gathering in unsafe conditions. COVID-19 can first present with GI symptoms. Did you get tested or has the fairly rapid (I'm sure not rapid enough for you) resolution of your symptoms been your indicator that the infection was not COVID-19? I ask because my colleagues have seen some patients (mostly pediatric) who had only GI symptoms and their parents' first thought was "just a GI virus", but because the pediatricians have been alert to atypical symptoms were tested and were positive. The importance of this was then keeping the kids out of school (which had resumed here) until they tested negative and to test their parents as well. You don't have tell me anything more about your medical history - I don't want to be nosy. Thanks for all the work you have done getting copies of Peter Keller's book. I hope your wife can stand the wait until "elective" surgery can be resumed. I know what this is like - we shut down all elective surgery during the first COVID wave and it delayed many procedures. For people in pain but whose surgery was considered "elective", this was a terrible waiting time. Best wishes to both of you. Steve Horii On Fri, Nov 27, 2020 at 3:51 PM Dennis Tillman W7pF <dennis@...> wrote: My apologies. I sure my absence the past 4 days has caused some concern. I |
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Re: 528A TV waveform monitor.
On 11/27/2020 3:19 PM, Roy Thistle wrote:
My question is... what do I (What can I) do with it?...I know itis/was intended for monitoring the NTSC television broadcast signal. You might as well ask "what can I do with a buggy whip?" You can monitor NTSC video waveforms. That is all that it is useful for. Back in my days as Chief Engineer of a small commercial NTSC TV station I used two Tek 528A waveform monitors. I had one on the bench, which sometimes was dragged into the field, and one in master control. Next to each was a Tektronix 1420 vectorscope (a different type of buggy whip). -- Dale H. Cook, Radio Contract Engineer, Roanoke/Lynchburg, VA |
Dale H. Cook
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