Test Equipment Anonymous (TEA) group therapy thread

[Berni]

You want "Warm white" LEDs advertised in the 4500-5500 range to get something between old blue-fluorescent and incandescent lighting. LED lighting is evil on a test bench, especially RGB as it's all controlled by poorly-approximated PWM from the cheapest COB processor they can manage. Be prepared; it generates HUGE amounts of common-mode noise that will drive you batshit crazy while you work.

Even plain white LEDs powered from a cheap SMPS make a lot of noise as the light strip is a huge antenna; the best, most tolerable setup I've gotten so far is to power them from an old linear wall wart with a couple 4700uf caps across the output and 1uF ceramic across the rectifiers.

You have been warned,


mnem
*Lit*

Yeah RGB is not such a good idea because it doesn't mix perfectly and you get poor CRI so colors don't look quite right.

We do already use some led lighting in the house and they can produce pretty good warm white and cool white tones. Some of them are led panels with built in supplies, some are the 'filament emulating' bulbs on 220V, some are in 12V halogen fixtues with a DC power supply brick running them. Hopefully the other strip i bought turns out to be the color temperature that i want.

As for running these i plan on using a  12V PSU module that i have a pile of. They are fancy expensive name brand PSUs with good ripple specs in the datasheet. I have already decided that i don't want to PWM them both for electrical noise reasons and for visual reasons. Il see if i can get away with a linear pass transistor regulator as these strips tend to loose a lot of brightness when run at 10V so i might be able to do it without massive heat sinks. If it ends up running too hot then i might use a buck converter with plenty of filtering.

I had lots of bad experiences with cheap crappy PSUs to know i want to avoid them in my own projects.

[Specmaster]

fat lot o' good being a member of this group did me!

swore an oath never to buy another nixie counter.

but decided to attend the fest over in york this morning and spotted this 5221a.

never would have touched it (honest!).....but had never seen one in a carry case before. (already have 2 each working 5221b's)

was about to put it back in its proper place when the guy snuck up behind me and whispered "5 bucks".   

damit!  i am only human after all.

had to wiggle the boards to get it counting.  but now it won't stop.

only 5 digits and 1Mhz.   

what is it goood for?  aaaabsolutely nothin'!

but it sure is cute.


ps  asta and i may both be sleeping in the garage if swmbo spots it.

No good joining this group if you want to quit buying stuff, this isn't the equivalent of a local AAA club

Neat, cute yes but as much use these days a chocolate fireguard, you could perhaps try to redeem yourself and prevent you and Asta sleeping in the garage by telling SWMBO that you thought it might make a very interesting clock

[Berni]

Well i haven't bought any test gear in a bit. I got outbid on the active scope probe that i wanted.

[nixiefreqq]

well........ it is advertised as a "group therapy thread". 

what?  turn an hp counter into a clock!

ye gods and little fishes!

what kind of rascals and varmints have I fallen in with on this site? 

[Specmaster]

Scope probes are easy to get passed SWMBO. I like the idea of an active one too.

[Specmaster]

well........ it is advertised as a "group therapy thread". 

what?  turn an hp counter into a clock!

ye gods and little fishes!

what kind of rascals and varmints have I fallen in with on this site?

I only said to say that he thought it would make a good clock, not actually make one from it.

[tggzzz]

but decided to attend the fest over in york this morning and spotted this 5221a.

was about to put it back in its proper place when the guy snuck up behind me and whispered "5 bucks".   

Know the feeling.

A similarly good salesman at a hamfest a couple of weeks ago got me to pay £5 for a Tek 2901 time mark calibrator, and wanted me to pay £5 for a Tek 115 pulse generator plus a Tek 178 linear IC test fixture plugin for a curve tracer. I managed to beat him up to £7

The 2901 works well (and is based around the only RTL that I've ever owned!), but one PCB and connector is scorched from an excessively hot dropper resistor and bridge rectifier. I'm not sure that I can be bothered to try and find if there actually is a fault.

The 115 also works well, now that I've replaced a calibration trimpot controlling the variable risetime.

[GerryBags]

We're enablers here, don't expect any advice to go cold turkey... unless it's so you can save up for even more TEA.

Take one of these, Kid..... Grow up, fast!

[Ero-Shan]

Part III

Still not satisfied, I continued searching. Until I found some more exotic DMMs. One seller offered 2 Nordmende DIVO 3362 (separate auctions ending 3 minutes apart) that looked interesting (and, a day before auction's end, dirt cheap). Marvels of german engineering!

This time also I could not attend the auctions end. I bid on both, maybe a bit more than I really wanted and with a small difference, hoping to get one. One, just one. Got both, and the price was only slightly below my bids. Grrr. Not even did I get a discount on the shipping costs.



They arrived on Thursday. Plugged in first one: It showed "+0  " - the 2 rightmost digits stayed black. Plugged in second one: It showed "    " i.e., nothing at all. It was also hard to switch on - the mains switch didn't like to move.
Since this one already was on my desk, I started with it. Mains fuse is blown. I decide to build a small box that sits between my variac and the DUT and lets me easily measure the current. This is when I also decide to use that variac/ammeter approach for all new gear. (I looked at the Datapulse after the DIVOs, for those who read Part II; the stories are in auction order).

Replace the fuse and crank up the voltage slowly. Way to much current drawn - the 100 mA would be met before reaching 60 volts. Find 2 caps with dead shorts. At 230 volts, it still sucks 160 mA (fuse is holding for a while), and voltages look about right. The display shows "+.  " with a rather bright dot. No digits, though.
I've printed the schematics (4 pages), but the scan is not the best quality, and the parts are too distorted to glue them together. This makes reading them rather hard, and after a while, I give up and turn my attention to the other one.
This one draws only 65 mA. Off goes the front. The display consists of 2 panaplex displays, a SP-351 (±1) and a SP-352 (88). Having seen by Onno's 3362 page http://www.glowbug.nl/neon/NM-DiVo3362.html, I pull the metal mask away so I can see the keep-alive dots. The SP-351 glows, the SP-352 does not. So I check the anode voltage at the drivers - all in the same ballpark. Looks like the SP-352 is a dud. Now I see firsthand what Onno described: The keep-alive cathode pins are bent down, prolonged with a short oiece of bare wire, and soldered to a narrow daughter board. (The display is already removed on the photo.)



Two things make me think. First, the display socket is cut out for the pins to be accessible. Second, the narrow strip is FR-1 (or FR-2), while all other boards are of higher quality. This looks a lot like they originally did not intend to use the keep-alive electrodes and later found out that they must be connected.

Engineer: "Sir, we, erm, found a quirk with the display of the 3362."
Project Leader: "What quirk? It does work, doesn't it?"
E: "Well, yes, it does, but ... But Sperry told us that the keep-alive pins must be connected for the display to keep working. We need to make a new display board."
PL: "A new display board? No way! We've just ordered a batch of half a bazillion. You find a workaround!"

And the marvelous german engineer found a workaround. The design, however, had lost its marvel appearance forever. Those stains can't be washed off.

But maybe I'm totally wrong and they did design it that way from the oustset. (Any layout person worth its salt should have been able to squeeze another 4 resistors on the display board, though. The array of 100 k resistors is another story.)

In order to verify the panaplex display, I make a simple checker:



First try without capacitor didn't work, tried with the definitely working SP-351 as well. After adding the cap, the SP-351 worked. The cap needs a bleed resistor, so I add one as well, but the cap must be manually plugged in there to discharge it. No big problem. So I think. Until I hear my variac make strange noises when I turn it up, followed by silence. Ugh. After discharging the cap, I plugged it on the wrong side of the diode.  100 µF at the variac output. Luckily, the fuse in it blew before the cap sprayed its innards all around the room. I fucked up big time, but got away with it. 
I disassemble the other DIVO as well and check its displays, too: Both SP-351 work, both SP-352 are dead.    So much for my luck.

Then I get the box with the panel meters out of the cramped attic. Sure enough, there's one with a panaplex display, but that is a 4½-digit one, so it might use a 3-digit module. I get lucky. The leading module has 3 "digits" (±188), followed by a SP-352. Bending the pins down makes me cringe, but what needs to be done must be done. After putting it in, I now have a 2½-digit display, the last digit is missing. Unsolder again, pull it out, and sure as hell the anode pin now lies flat at the display.    I'm able to pull it up and straighten it out without it braking. Those pins are quite finicky! At second try, I succeed in pushing it into its socket without bending a pin. Lo and behold! The thing works! As I have no double sided sticky tape, I use a bit of hot glue to fix the mask. A bit of cleaning the whole thing, then a sloppy calibration. 10.04 is within the 0.5 % from 10 volts as specified. Resistors look OK, too.



Now what was all this for? Will I ever use this instrument? I highly doubt it. Did I spend all that money and several hours just for a single forum post? Or because I could not even dream of such a meter at its time? Was it worth killing a perfectly working (and more precise) panel meter for it?
This acquisition made me very uneasy.

Note: I started this posting around 13.15. At 14.00 I saw the weather improved to a point where I remembered my promise to mow the lawn (Did I say lawn? My backyard's more like a meadow). Finished with that, I had to bake my cake (Saturday's it's coffee and cake as lunch & dinner), already an hour late. Now it is 19.45. Do I get a price for taking the longest time ever to finish a posting?

[nixiefreqq]

well........ it is advertised as a "group therapy thread". 

what?  turn an hp counter into a clock!

ye gods and little fishes!

what kind of rascals and varmints have I fallen in with on this site?

I only said to say that he thought it would make a good clock, not actually make one from it.


ok.....got it.  you weren't actually suggesting that I commit an atrocity on one of bill and daves counters.

only that i should deceive swmbo with the idea.

hmmmmmmm.  sounds like a plan


ps  swmbo was born in some kind of RAF field hospital in suez.  (I've seen her birth certificate).   have also seen pics of her in a us army uniform squirreled away in a box down in the basement.   have always suspected she may have been one of the characters in that "kingsman" movie.  this could all go terribly wrong.

[Ero-Shan]

Just regular Google foo with rather fuzzy search terms (how I usually start). Since Google delivers personalized and localized search results, I tend to use both, Startpage and Google. I think I searched for "sd datapulse 101 schematic" and "sd datapulse 101 service manual" or "datapulse 101 service manual" on google first.

Need to check out the 100 manual for viewing pleasure

I switched to Startpage some time ago (for privacy reasons), and was under the impression that they used Google. But there are fewer hits with Startpage.

[Ero-Shan]

So I powered it up. I do this now with a variac and monitoring the current while.

Ob reminder: don't do that with equipment that has a switched-mode power supply. The constant power output plus low input voltage implies a high input current.

I had a fight with me whether I should mention that this does not work work for switchers. But I decided that this was obvious.
But you're right, it is worth noting.
The input current is also close to nil until it suddenly springs to life. There's just no slow ramping up.

[PA0PBZ]

Do I get a price for taking the longest time ever to finish a posting?

I'm not sure about the price but I surely enjoyed reading the post! 

[Specmaster]

well........ it is advertised as a "group therapy thread". 

what?  turn an hp counter into a clock!

ye gods and little fishes!

what kind of rascals and varmints have I fallen in with on this site?

I only said to say that he thought it would make a good clock, not actually make one from it.


ok.....got it.  you weren't actually suggesting that I commit an atrocity on one of bill and daves counters.

only that i should deceive swmbo with the idea.

hmmmmmmm.  sounds like a plan


ps  swmbo was born in some kind of RAF field hospital in suez.  (I've seen her birth certificate).   have also seen pics of her in a us army uniform squirreled away in a box down in the basement.   have always suspected she may have been one of the characters in that "kingsman" movie.  this could all go terribly wrong.

Br afraid, very afraid 

[Ero-Shan]

Do you know the two-volume 'Philips Lehrbriefe'? I used them in 2 cases to explain electronics to people that won't get nit otherwise. Especially their transistor explanation was ingenious.
Did you read my post about the PM3088 looking for a caretaker?
Where I am at odds with them are their desk multimeters. Both the PM2519 and the PM2521 have interesting features. But they could not think of combining them. THAT would have neen a nice instrument.

I remember vaguely having seen the "Lehrbriefe" a long, long time ago (pictures of the cover, actually, not the real thing).  Are they available online?The book accompanying the EE2000 wasn't bad, either. Are they available online?
And I missed the PM3088 post. (Search finds nothing, Startpage also draws a blank. Sounds like a CRO?)
I still don't understand why Philips built such an incredible range of instruments with often rather similar features. There certainly was room for streamlining the portfolio. Or making a "best of both worlds". Pity.

[Ero-Shan]

what is it goood for?  aaaabsolutely nothin'!

Damn it! I started today with a song quote and was tempted to put one in every posting. But most of them would have been too obscure, so I dropped the idea. I now wish I had followed up, anyway, even if no one spotted them.

Calling yourself nixiefrqq and passing up on that device would not have worked. You know you have to live up to it. 

[orin]

Not having a manual for the 101 (maybe the available 100 manual/schematics is reasonably close), I wasn't in the mood to investigate further.
For the moment, I count this as a blank. 

All hail the mighty overlords of web services!
This might be what you are looking for: https://kb8ojh.net/images/datapulse-101.pdf

Kind regards, Frederik

Edit: On a side note, what a BEAUTY! this manual cover is!

I have the hardcopy of the second edition of this manual!  Dated May 1968 and now saying SYSTRON DONNER on the cover.

[GerryBags]

I enjoyed reading that post, too, Ero-Shan. I also know that feeling of owning something that would have been completely out of reach when new, however behind the curve is it now. Occasionally, though, it seems that a capability of older tech turns out to be just the thing to make some modern marvel work. An old example (but that's where I'm up to in my race to learn), but I'm thinking of the mercury-wetted reed relay used in the really early Tek trigger circuits, and pulse gens which had a rise time that is difficult to surpass even now.

So old test gear is not always so far behind the curve. Once I've finished my 2467B it will be hard to find a modern scope for ten times what I paid that will show faint, low-repetition signals better.... hopefully.

[frozenfrogz]

I switched to Startpage some time ago (for privacy reasons), and was under the impression that they used Google. But there are fewer hits with Startpage.

Sadly that is true in my book. No one is anywhere near competing with Google in that regard and all services using the Google database seem to only be able to use a limited set. There are some specialty site for meta crawling, but the scope for those is pretty limited.

[mnementh]

While I'm waiting for the parts to arrive for the Tek 465 I figured I'd revisit the Fluke 8000A DMM drift issue and power supply modifications. In my previous posts on the same subject I was able to show that I reduced overall warm up drift from approx 40mv to approx 20mv on the 20V DC range by installing 7815/7915 linear regulators on the +/- 15V supplies. Through discussions here it was recommended that additional drift reduction might be possible by regulating the currently unregulated +5V supply. So today a modeled a modification and I have the results.

To simulate a “real world” mod I decided to use an actual 7805 regulator. I disabled the unregulated Fluke supply and tacked in the 7805. The 7805 is fed by an external supply of +9V. The output of the 7805 is a steady +5.037V. The results are in the pictures. Pix 1 is right at power on. A steady +10.00V with only an occasional blip to +9.99V. Pix 2 is 1.5 hours later. Again, steady +10.00V with only an occasional blip to +10.01V. Conclusion: Any appreciable drift has been almost completely eliminated and this mod is worth it.    I don't have a suitably sized transformer to fit into the case so I'll have to order one. Once I do that I'll post pictures and a schematic of the modification.       

Awresome! I've abused 7805s and LM1117s similarly in oodles of repair/upgrade/mod projects; I often wonder why it wasn't the first thing to come to mind to the original designers. 78xx regulators aren't cliche'; they're basic building blocks, even if they do waste a few mW as heat.

Surely you have an old 8-16V wall wart you can gut for the transformer and rectifier?


mnem
*Working my way down the list*

[mnementh]

You want "Warm white" LEDs advertised in the 4500-5500 range to get something between old blue-fluorescent and incandescent lighting. LED lighting is evil on a test bench, especially RGB as it's all controlled by poorly-approximated PWM from the cheapest COB processor they can manage. Be prepared; it generates HUGE amounts of common-mode noise that will drive you batshit crazy while you work.

Even plain white LEDs powered from a cheap SMPS make a lot of noise as the light strip is a huge antenna; the best, most tolerable setup I've gotten so far is to power them from an old linear wall wart with a couple 4700uf caps across the output and 1uF ceramic across the rectifiers.

You have been warned,


mnem
*Lit*

Problem is that over here in the UK we are being driven into using LEDs for all our lighting or florescent as it now illegal for shops to sell incandescent light bulbs anymore. Its all part of the UK governments commitment to the Paris Agreement that your President Chump threw out. So we have horrendous amounts of radio interference these days, AM radio is almost useless unless out in the middle of field somewhere.

I have strings under the cabinets in my kitchen that I can pick up a room and a half away by holding my 'scope probe at just the right angle. But it's not just RF noise... it's carried common-mode as well and shows up as noise on your 'scope you can't make sense of. I'm talking in some cases a couple hundred mV.

I don't even want to talk about the whole CFL/LED lighting debacle... it's utter BS. Over here they're subsidized by the power companies so they can get away with charging the same amount for less electricity delivered, thereby pushing off necessary infrastructure upgrades and of course because they can continue burning dead dinosaurs to make electricity for a few more years. Of course, nobody considers the e-waste they all become, and as they're a combination of electronics and multiple types of plastic, they are very hard to recycle PROFITABLY therefore most consumer CFL/LED lighting winds up in landfills. 

The production and disposal waste footprints are clearly much larger than incandescent which are 100% easily, cheaply and profitably recycled. Most of the figures they use to demonstrate gains they attribute to CFL and LED lighting include gains from lighting automation deployed at the same time; their results are artificially skewed as a result. 

If we were really committed to "Green Energy" we'd have truly clean energy infrastructure that could easily handle the wasted electricity of incandescent by now; especially now that nearly every large-scale lighting application is automated. Anything that prolongs our switch from burning fossil fuels for electricity to truly green energy is just kicking the problem down the road for future generations to deal with. 

Our children will be paying a huge debt the hard way once all this poisonous plastic and semiconductor production waste starts leeching into the groundwater; that is if near-ubiquitous fracking waste doesn't make the words "safe to drink" a perverted joke first. 

[SNIP]
mnem
*Lit*

By the way, I PM'd you did you get it?

Me? Not seeing anything new from you.


Cheers,


mnem
American Corporate: Poisoning the world for fun & profit.

[Specmaster]

You want "Warm white" LEDs advertised in the 4500-5500 range to get something between old blue-fluorescent and incandescent lighting. LED lighting is evil on a test bench, especially RGB as it's all controlled by poorly-approximated PWM from the cheapest COB processor they can manage. Be prepared; it generates HUGE amounts of common-mode noise that will drive you batshit crazy while you work.

Even plain white LEDs powered from a cheap SMPS make a lot of noise as the light strip is a huge antenna; the best, most tolerable setup I've gotten so far is to power them from an old linear wall wart with a couple 4700uf caps across the output and 1uF ceramic across the rectifiers.

You have been warned,


mnem
*Lit*

Problem is that over here in the UK we are being driven into using LEDs for all our lighting or florescent as it now illegal for shops to sell incandescent light bulbs anymore. Its all part of the UK governments commitment to the Paris Agreement that your President Chump threw out. So we have horrendous amounts of radio interference these days, AM radio is almost useless unless out in the middle of field somewhere.

I have strings under the cabinets in my kitchen that I can pick up a room and a half away by holding my 'scope probe at just the right angle. But it's not just RF noise... it's carried common-mode as well and shows up as noise on your 'scope you can't make sense of. I'm talking in some cases a couple hundred mV.

I don't even want to talk about the whole CFL/LED lighting debacle... it's utter BS. Over here they're subsidized by the power companies so they can get away with charging the same amount for less electricity delivered, thereby pushing off necessary infrastructure upgrades and of course because they can continue burning dead dinosaurs to make electricity for a few more years. Of course, nobody considers the e-waste they all become, and as they're a combination of electronics and multiple types of plastic, they are very hard to recycle PROFITABLY therefore most consumer CFL/LED lighting winds up in landfills. 

The production and disposal waste footprints are clearly much larger than incandescent which are 100% easily, cheaply and profitably recycled. Most of the figures they use to demonstrate gains they attribute to CFL and LED lighting include gains from lighting automation deployed at the same time; their results are artificially skewed as a result. 

If we were really committed to "Green Energy" we'd have truly clean energy infrastructure that could easily handle the wasted electricity of incandescent by now; especially now that nearly every large-scale lighting application is automated. Anything that prolongs our switch from burning fossil fuels for electricity to truly green energy is just kicking the problem down the road for future generations to deal with. 

Our children will be paying a huge debt the hard way once all this poisonous plastic and semiconductor production waste starts leeching into the groundwater; that is if near-ubiquitous fracking waste doesn't make the words "safe to drink" a perverted joke first. 

[SNIP]
mnem
*Lit*

By the way, I PM'd you did you get it?

Me? Not seeing anything new from you.


Cheers,


mnem
American Corporate: Poisoning the world for fun & profit.

Haha, yep we have the same load of BS over, with the way that bulbs are supplied and the cost of power also increased to cover their costs every year we seem to burn less electricity and yet our bills never go down and yes there is plenty of green electricity being generated as well.

As to my PM, check in your message tab at the top of the page? I sent you a personal message on April 26, 2018, 11:11:14 am

[Specmaster]

This is OT but I don't know how else to resolve the problem. It seems that our index page is having problems the only way I get onto the forum is from a direct link in response to an email telling me of a new reply to a thread that I subscribe to. Once I get on the forum by clicking that link, I still cannot get access to the main index page, is anyone else having the same issues?

[ataradov]

Everyone is having the same problem - https://www.eevblog.com/forum/chat/website-error-reports/msg1503256/#msg1503256

[mnementh]

ok.....got it.  you weren't actually suggesting that I commit an atrocity on one of bill and daves counters.

only that i should deceive swmbo with the idea.

hmmmmmmm.  sounds like a plan.


ps  swmbo was born in some kind of RAF field hospital in suez.  (I've seen her birth certificate).   have also seen pics of her in a us army uniform squirreled away in a box down in the basement.   have always suspected she may have been one of the characters in that "kingsman" movie.  this could all go terribly wrong.

I know my wife could probably still break me in half if she got angry enough; that was part of the allure when we first got together. I do love me an inconvenient female; they're the only kind worth the effort.


mnem
I've got her right where she wants me!