Author Topic: Test Equipment Anonymous (TEA) group therapy thread  (Read 1722282 times)

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Online bd139

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10675 on: May 15, 2018, 10:04:21 am »
Ob porn: the front panel showing rise and fall time controls, and one interior shot showing old-school wiring looks and, if you look closely on the left, 863pF, 908pF and 9.85nF capacitors.

That's a thing of beauty!  :-+

Another xfce user I see as well :D
 

Offline Specmaster

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10676 on: May 15, 2018, 10:15:31 am »
I'm not at all sure that I'm understanding you with this one, the TF930 has a USB port but that is just another option for providing portable power, the TGP110 is purely 240v driven and neither of them has a GPIB connector, so in what way was you thinking of computer linking them?
The USB port is not just for power.  :) The TF930 is SCPI enabled, even though it uses a shorthand dialect. You can control all its functions through a PC.
So it is, should have RTM more thoroughly. :palm:
I probably skipped over that bit TBH seeing as I have no interest in using that feature although its nice to have the ability should I ever want too at a later date  :phew:
Who let Murphy in?
 

Offline Cerebus

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10677 on: May 15, 2018, 10:20:17 am »
Having said that, I recently picked a Tek 115 up for £5, and that does one thing a pattern generator won't: have (independently) variable rise and fall times. Mind you, neither does that TTI.

I'll have to try and find some schematics for that. I had cause recently to design (read lash up) a pulse generator with variable symmetric rise and fall times; pretty easy really, a couple of adjustable constant current sources and a diff. pair as a current switch. What wasn't obvious was how to make the rise and fall times independently adjustable other than doubling up the former circuit and adding some switching diodes. I'll have to look and see if Tek had a cleaner solution.

Edited to add: Just downloaded the Tek 115 manual (with schematics) from W140. How to do it is head-slappingly obvious, once you've seen it - bet it took the original designer a few days to figure out though.
« Last Edit: May 15, 2018, 10:28:42 am by Cerebus »
Anybody got a syringe I can use to squeeze the magic smoke back into this?
 

Offline Specmaster

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10678 on: May 15, 2018, 10:24:46 am »
Oh dear RS are struggling it seems, the saga with my 3478A rolls forwards. Despite the order tracking page of the web site showing it as been dispatched as of last Wednesday and it not arriving back as of Friday, I called them to be told that it was still in the lab and should be leaving Monday.

I need to pop out for a short time later today, so I thought I'd check with RS again to see what the latest state of play was. It now has completed the calibration and should be leaving today or tomorrow and I was told that the lab are saying that they are running a couple of days behind schedule due to the Bank Holiday, so 1 days holiday adds 2 days onto their turnaround time?

So it now looks like its going to be 2 full weeks from collection to return on what was claimed to be a 5 day service?
Who let Murphy in?
 

Online bd139

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10679 on: May 15, 2018, 10:30:19 am »
Having said that, I recently picked a Tek 115 up for £5, and that does one thing a pattern generator won't: have (independently) variable rise and fall times. Mind you, neither does that TTI.

I'll have to try and find some schematics for that. I had cause recently to design (read lash up) a pulse generator with variable symmetric rise and fall times; pretty easy really, a couple of adjustable constant current sources and a diff. pair as a current switch. What wasn't obvious was how to make the rise and fall times independently adjustable other than doubling up the former circuit and adding some switching diodes. I'll have to look and see if Tek had a cleaner solution.

Damped miller integrator? I built one of them a few years ago to get adjustable rise time. If you stuff a small cap across B-C junction with a (trimmer in my case) resistor in series with it. Doesn't affect bias yet slows the transistor down.


Oh dear RS are struggling it seems, the saga with my 3478A rolls forwards. Despite the order tracking page of the web site showing it as been dispatched as of last Wednesday and it not arriving back as of Friday, I called them to be told that it was still in the lab and should be leaving Monday.

I need to pop out for a short time later today, so I thought I'd check with RS again to see what the latest state of play was. It now has completed the calibration and should be leaving today or tomorrow and I was told that the lab are saying that they are running a couple of days behind schedule due to the Bank Holiday, so 1 days holiday adds 2 days onto their turnaround time?

So it now looks like its going to be 2 full weeks from collection to return on what was claimed to be a 5 day service?


 

Offline Mr. Scram

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10680 on: May 15, 2018, 10:38:41 am »
So it is, should have RTM more thoroughly. :palm:
I probably skipped over that bit TBH seeing as I have no interest in using that feature although its nice to have the ability should I ever want too at a later date  :phew:
It's part of why I bought it and I just tested the feature last week. I'm hooking everything up, so you can build fairly nifty and convoluted automated test setups.
 

Offline Specmaster

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10681 on: May 15, 2018, 10:41:36 am »
So it is, should have RTM more thoroughly. :palm:
I probably skipped over that bit TBH seeing as I have no interest in using that feature although its nice to have the ability should I ever want too at a later date  :phew:
It's part of why I bought it and I just tested the feature last week. I'm hooking everything up, so you can build fairly nifty and convoluted automated test setups.
How would the TGP110 fit into that then, it only has a IEC mains socket?
Who let Murphy in?
 

Offline Mr. Scram

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10682 on: May 15, 2018, 10:44:17 am »
How would the TGP110 fit into that then, it only has a IEC mains socket?
Exactly my thoughts. It also seems I can replicate what it can do to a satisfactory level with what I already have.
 

Offline Specmaster

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10683 on: May 15, 2018, 10:51:26 am »
Oh dear RS are struggling it seems, the saga with my 3478A rolls forwards. Despite the order tracking page of the web site showing it as been dispatched as of last Wednesday and it not arriving back as of Friday, I called them to be told that it was still in the lab and should be leaving Monday.

I need to pop out for a short time later today, so I thought I'd check with RS again to see what the latest state of play was. It now has completed the calibration and should be leaving today or tomorrow and I was told that the lab are saying that they are running a couple of days behind schedule due to the Bank Holiday, so 1 days holiday adds 2 days onto their turnaround time?

So it now looks like its going to be 2 full weeks from collection to return on what was claimed to be a 5 day service?



They need to give them lab monkeys more bananas then  :-DD
Who let Murphy in?
 

Online xrunner

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10684 on: May 15, 2018, 11:47:27 am »
Somebody leaked a picture of tautech in his lab!  :scared:


I am a Test Equipment Addict (TEA) - by virtue of this forum signature, I have now faced my addiction
 
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Offline VK5RC

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10685 on: May 15, 2018, 12:34:44 pm »
That's not tautech - that's me - before I went bald (on the top of my head only)!!

I got given a non-working Tek 7603 - but no plug-ins so I bought 7B50A 7B53A 7A16A 7A18, some capacitor adaptor plates - so far the caps test OK on in circuit ESR.
Also bought one of Daves little pocket DMM Sanwa PM300- it comes in a really funky little case.
Whoah! Watch where that landed we might need it later.
 

Offline tggzzz

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10686 on: May 15, 2018, 12:56:31 pm »
Ob porn: the front panel showing rise and fall time controls, and one interior shot showing old-school wiring looks and, if you look closely on the left, 863pF, 908pF and 9.85nF capacitors.

That's a thing of beauty!  :-+

Another xfce user I see as well :D

Yup. I chose that because
  • there's nothing kewl about it; it just works without me having to think about it
  • works nicely on a 2012 1.6GHz/1GB Atom netbook - and wonderfully on anything newer/bigger
and I standardised on it before Linus publicly stated he had :)

Now that Unity has bitten the dust, maybe I'll try Mate/Cinnamon - but quite frankly I can't see any benefit to reeducating myself.
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
Having fun doing more, with less
 

Online bd139

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10687 on: May 15, 2018, 01:00:07 pm »
Don’t bother. It’s like fighting a crocodile. Xfce is the safe house in the woods. Desktop’s job is to get out of the way and let the applications do their thing, not be clever or fancy.

Just blew some cash on some storage for parts in hobbycraft. Decided to organise and clear out all the shit that is in my cupboards.  It can fund some new toys then :D
 

Offline mnementh

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10688 on: May 15, 2018, 01:06:24 pm »
...I got rid of my adult supervision quite a while ago, so I have no one to protect me now...

Aha!  Now I understand how such a purchase is possible.

Yay for lack of adult supervision!!



Hmmm...  On second though, perhaps some adult supervision might be a good idea...

Nahhh, screw it. That ship has sailed.  Off to the bay of evil!!

-Pat

They're congregating...or perhaps colluding. Did you recently schlepp some of the units I see there?

Indeed I did.  You obviously recognize the pile just to the left of center as my recent score.

-Pat

You can just "misplace" that Makita chopsaw in my direction any time you want to stop stubbing your toes on it; my crusty old DeWalt (Boutique branded Black & Decker pecker wrecker) is about on its last legs. I expect the gearbox to actually grenade pretty much every time I pull the trigger now...


mnem
Of course, before i can use it, I'll need to rebuild the stinger on my MIG... oh the heartbreak.  :-DD
 

Offline mnementh

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10689 on: May 15, 2018, 01:14:09 pm »
They're congregating...or perhaps colluding.

Excellent collective noun: "a collusion of test equipment"

When I was young, and my electronics bits and pieces were scattered from hell to breakfast all over the house... my mother used to tell me they were plotting to overthrow her tyranny. She would point out the test gear I happened to be using at the time (usually assembled in stacks in a circular fashion on the floor behind and table in front of me) which was always old and crunky and scarred as it was all third or fourth-hand, and say they were holding court, with me the accused in the middle.

*Sigh*

Remember when we just did it for the fun of learning?!?


mnem
*Miss you mom*
 

Offline Cerebus

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10690 on: May 15, 2018, 01:18:58 pm »

I'll have to try and find some schematics for that. I had cause recently to design (read lash up) a pulse generator with variable symmetric rise and fall times; pretty easy really, a couple of adjustable constant current sources and a diff. pair as a current switch. What wasn't obvious was how to make the rise and fall times independently adjustable other than doubling up the former circuit and adding some switching diodes. I'll have to look and see if Tek had a cleaner solution.

Damped miller integrator? I built one of them a few years ago to get adjustable rise time. If you stuff a small cap across B-C junction with a (trimmer in my case) resistor in series with it. Doesn't affect bias yet slows the transistor down.


No. It's quicker to draw in LTSpice (and even simulate) than it would be to give a purely word description. Please excuse the crudeness of the model, I didn't have time to paint bias it properly or create a decent output clamp. In a fully fledged version you'd use something a bit better than a pair of back to back diodes to guarantee something like a flat top.

There's two differential pairs acting as current switches. The top one switches the charging current, the bottom discharging. You set the current of the constant current sources Irise and Ifall to control the rise and fall times.



The output:





That's the Tektronix version in rough outline. The version I used before didn't have the top differential pair, just a current source, and the current source off the tail of the bottom pair was twice the value of the top current (i.e. Ibottom = -2 * Itop). Switch on and you draw (Itop - 2*Itop) out of the capacitor, off and just the top current source supplies Itop.

« Last Edit: May 15, 2018, 02:05:23 pm by Cerebus »
Anybody got a syringe I can use to squeeze the magic smoke back into this?
 

Offline mnementh

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10691 on: May 15, 2018, 01:32:12 pm »
Heads everyone, TTi TGP110's are back in stock again and they have 18 in cream and 19 in grey.

I'm not really sure why I would want a pulse generator; any of the pulses I would want would be more conveniently generated by a pattern generator.

Having said that, I recently picked a Tek 115 up for £5, and that does one thing a pattern generator won't: have (independently) variable rise and fall times. Mind you, neither does that TTI.

The Tek 115 is remarkably versatile, being able to generate double pulse and, with an external signal triggered bursts. The TTI doesn't look like it does that either.

Example, with equal rise/fall times:


Ob porn: the front panel showing rise and fall time controls, and one interior shot showing old-school wiring looks and, if you look closely on the left, 863pF, 908pF and 9.85nF capacitors.
Oh, that is quite delicious... has much of the same "precision analog built for the space program" feel as my old 454... also would be a good module (if collected together with a dozen of its brothers) for analog computing or synthesizer stacks.


mnem
That's right Ted, I'm thinking of you.
 

Online bd139

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10692 on: May 15, 2018, 01:34:11 pm »
@Cerebus: Thanks for taking the time to document that properly. Very neat solution to the problem.

So fundamentally it's sourcing/sinking fixed current from the 1n cap. Similar to function generator ramp generators.
 

Offline mnementh

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10693 on: May 15, 2018, 01:44:09 pm »
That's not tautech - that's me - before I went bald (on the top of my head only)!!

I got given a non-working Tek 7603 - but no plug-ins so I bought 7B50A 7B53A 7A16A 7A18, some capacitor adaptor plates - so far the caps test OK on in circuit ESR.
Also bought one of Daves little pocket DMM Sanwa PM300- it comes in a really funky little case.

Whuf! That PM300 is a pricey little devil. What makes it supposedly better than the little Radidio Shack meters I used to buy for $20?


mnem
Urrrk.
 

Offline Cerebus

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10694 on: May 15, 2018, 01:57:31 pm »
@Cerebus: Thanks for taking the time to document that properly. Very neat solution to the problem.

So fundamentally it's sourcing/sinking fixed current from the 1n cap. Similar to function generator ramp generators.

I think elegant is the word; as in mathematics and programming, elegant solutions are particularly satisfying. On Tim's Tek 115 there's a bunch of capacitors switched for the rise time knob, and the rise time and fall time multiplier knobs are just pots in the emitters of single transistor constant current sources.
Anybody got a syringe I can use to squeeze the magic smoke back into this?
 

Offline tggzzz

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10695 on: May 15, 2018, 04:35:03 pm »
They're congregating...or perhaps colluding.

Excellent collective noun: "a collusion of test equipment"

When I was young, and my electronics bits and pieces were scattered from hell to breakfast all over the house... my mother used to tell me they were plotting to overthrow her tyranny. She would point out the test gear I happened to be using at the time (usually assembled in stacks in a circular fashion on the floor behind and table in front of me) which was always old and crunky and scarred as it was all third or fourth-hand, and say they were holding court, with me the accused in the middle.

*Sigh*

Remember when we just did it for the fun of learning?!?
*Miss you mom*

*aaaaahhhhh*. Yes, it seems like yesterday. In fact it was yesterday (as well) :)
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
Having fun doing more, with less
 

Offline tggzzz

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10696 on: May 15, 2018, 04:41:09 pm »
Heads everyone, TTi TGP110's are back in stock again and they have 18 in cream and 19 in grey.

I'm not really sure why I would want a pulse generator; any of the pulses I would want would be more conveniently generated by a pattern generator.

Having said that, I recently picked a Tek 115 up for £5, and that does one thing a pattern generator won't: have (independently) variable rise and fall times. Mind you, neither does that TTI.

The Tek 115 is remarkably versatile, being able to generate double pulse and, with an external signal triggered bursts. The TTI doesn't look like it does that either.

Example, with equal rise/fall times:


Ob porn: the front panel showing rise and fall time controls, and one interior shot showing old-school wiring looks and, if you look closely on the left, 863pF, 908pF and 9.85nF capacitors.
Oh, that is quite delicious... has much of the same "precision analog built for the space program" feel as my old 454... also would be a good module (if collected together with a dozen of its brothers) for analog computing or synthesizer stacks.

Actually, it is a module. If you look at the lower left front panel you will see the single screw securing it in its slide-in housing. Took me a while to figure out that I didn't need to remove panels to get at the innards, doh.

Much more detailed porn here: https://www.flickr.com/photos/anachrocomputer/albums/72157690644170820

Keep an eye out for the two hidden tunnel diodes and the roll of solder. And the gold, of course.
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
Having fun doing more, with less
 

Offline Specmaster

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10697 on: May 15, 2018, 04:49:16 pm »
That sure is a nice piece of kit, so much porn to look at and I love the nice touch to include a small coil of silver solder, doubt that you'd get that sort of attention to detail and thoughtfulness today. :-+
Who let Murphy in?
 

Offline GerryBags

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10698 on: May 15, 2018, 05:32:37 pm »
I'm willing to bet the guys who worked at Tek knew they had one of the best jobs in the world back in the 60's, but i wonder i they would have believed someone who told them that what they were producing would be as admired and sought after as they are, nearly two decades into the 21st Century?

Beautiful stuff!  :-+
 

Offline Cerebus

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #10699 on: May 15, 2018, 05:32:59 pm »
That sure is a nice piece of kit, so much porn to look at and I love the nice touch to include a small coil of silver solder, doubt that you'd get that sort of attention to detail and thoughtfulness today. :-+

Tektronix often included solder because it was something a bit out of the ordinary that had to be used to meet the instrument's specifications, or so as not to destroy the plating on a particular component, or even the whole component.

With 100 MHz scopes a cheap commonplace nowadays it's easy to forget that many Tektronix instruments (with modest specification in modern terms) were on the bleeding edge of technology in their day and Tek indulged in all sorts of tricks to squeeze the last drop of performance out of the components and materials they had available. If that meant using non-standard solders for some joints then that's what they did, and as they expected that, for routine repairs, you'd want to fix things yourself they included some with the instrument.
Anybody got a syringe I can use to squeeze the magic smoke back into this?
 


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