Test Equipment Anonymous (TEA) group therapy thread

[Cerebus]

Q: "Shall I replace the RIFAs in this device?"

A: "Is the bear Catholic?"¹


¹Comes from this:
- Is the Pope Catholic?
- Does the bear shit in the forest?

 

I think you can assume that the collected works of Gilbert Shelton have been required reading at some time for most of the TEA shop.

"TEA will get you through times of no money better than money will get you through times of no TEA."

"Cheese stuffed mice. A meal that virtually prepares itself."

[xrunner]

Correction to the explanatory post, the question on Discord was from Zucca not Neomys Sapiens.

Retarded design choice for me.

Man! 

Calling hp retarded ... them's fightin' words in these parts. 

[tonyalbus]

Correction to the explanatory post, the question on Discord was from Zucca not Neomys Sapiens.

Retarded design choice for me.

Man! 

Calling hp retarded ... them's fightin' words in these parts. 

Those calcutators...
Once i was lazy.. oh wait.. once i did not wanted to walk upstair and tried using my wifes HP financial calculator..
she is clearly way smarter than i am.  i am unable to use it.

[Cerebus]

Added a charge line to my pulser. Next step is working on better shaping of the pulse top....but that's another day's problem. 

Also got a wild pic while experimenting with a long exposure app on my phone. I think the lighting confused it.

Funky !

Can we have a pic with a clean pulse and time base setting so we can measure the rise time ? 

And forgive the stupid newbie question but is a "charge line" ,  not much info online to my dismay. Found " charging line " or "line charging", often not even pertaining to electronics...

What does it consist of, its role and how why did you expect it might modify the rise time (in your last post you said rise time without charge line was irrelevant ) ?  I mean I can see it lengthens the pulse of course, but what's the impact on rise time ?

Thanks ! 

The charge line is simply a coaxial cable where it's capacitance has been used.

Here is my charge line:


This is the schematic of the Jim-Williams fast pulse generator:


C₁ is essentially the capacitance of the coax cable.

HTH

Edit:

Here has somebody made a charge line on the PCB:


Source:
http://www.siliconvalleygarage.com/projects/picosecond-pulser.html

Not quite as simple as that. The point of using a length of coax, instead of a much more compact capacitor, is to make use of the distribution of the charge across time and space to match your required signal. It's moving from using lumped components to distributed components.

Basically, welcome to the weird world of RF where you can make a filter just with copper traces on a board, and a black robe and a chicken/goat sacrificing habit are a necessity.

[bd139]

I’m all over that.

sips another mouthful of goat blood

[Neomys Sapiens]

Oh, I "accidentally" acquired a lot of 18 outside micrometers on ebay...

https://www.ebay.co.uk/itm/JOBLOT-18x-MITUTOYO-STARRETT-MOORE-WRIGHT-OUTSIDE-MICROMETERS-TOOLS-/265270785540

As your actual measurement needs will be probably fulfilled by a subset of those, the micrometer screws make useful adjusters for precision mechanics too!

[Neomys Sapiens]

I’m all over that.

sips another mouthful of goat blood

Don't you have an order against visiting that petting zoo?

[Robert763]

There was a vintage slightly crusty HP current probe available on evilbay in Oz  eBay auction: #165025864057

Here's another one -- not as cheap but still interesting. NAWTS, of course.

There is a big difference between the HP and the Tek (apart from obvious colour and age). The HP is AC only, the Tek is AC and DC.

Which Tek ? 
The infamous P6021 and P6022 current probes are AC only probes also and both can be paired with the Type 134 current probe amp for 50 ohm output.

The Tektronix P6042 in the link

[Robert763]

There was a vintage slightly crusty HP current probe available on evilbay in Oz  eBay auction: #165025864057

Here's another one -- not as cheap but still interesting. NAWTS, of course.

There is a big difference between the HP and the Tek (apart from obvious colour and age). The HP is AC only, the Tek is AC and DC.

Which Tek ? 
The infamous P6021 and P6022 current probes are AC only probes also and both can be paired with the Type 134 current probe amp for 50 ohm output.

Apart from not seeing the point of displaying a straight line on a scope I have a pair of nice 6 1/2 digit meters with logging capabilities and a set of really accurate shunts I can probe if needed for DC or near DC that I could easily look at on a scope channel if required.

So call me curious and it has been a while since I added to the TEA toys so I thought I should

DC current probes for scopes are useful for signals below about 20-30Hz. They also let you see combined AC and DC signals. For example bias current and the signal.

[Robert763]

I need to check the OP to be sure, but I don't think we've had "you know you're a TE addict when you use a new toothbrush to clean rusty transistors rather than your teeth".

Tesco website is a bit fooked atm, DDOS? Needed more toothbrushes...   

Had all the topside boards out of the 5245L, gently cleaned (not gently enough, a rusty transistor leg broke, plugging the Metcal in right now), adjusted some clearances (some of those TO-5 case were, shall we say, inadvertently thermally coupled?).
Swapped some display boards around, and as soon as I've fixed that tranny leg on the A18 display board I'll give it a burl.

Who uses their teeth to clean transistors?

Same people that use their teeth to strip wire insulation.

I got cured of that habit as a teenager when I used my teeth to strip a bit of zip cord. Only to find my brother had plugged the other end in to a 240V outlet with out me noticing. 
That hurt 

And your still here to tell the tale, were you standing on a nice thick rubber mat by any chance at the time? 

Nope in my bedroom, standing by the door (behind which was the socket the lead was plugged into. I woke up on the other side of the room with the bitten off end of the zip cord in my mouth. This was mid seventies so wired fuses in the consumer units, RCDs were unheard of.
I was very lucky. I had a sore jaw and could not taste anything for bout a week though.

[Robert763]

Question for RPN hp calculators lovers.

I just wrote this up before you posted ...

So last night when the forum was down I was on Discord and Zucca was wondering why his hp 42S was displaying what seemed to him to be a wrong number of digits after the radix. I have the original manual but it doesn't really explain this very well.

For example, he set the display to ENG 03. He then recalled pi and was presented with

3.124E0

I believe he then multiplied by 10 and viewed this

31.42E0

He was not sure why it didn't display three decimal places like this

31.416E0

^^^ that is what it displays when I set it to ENG 04 (it rounds the last digit up from 5 to 6).

Well, it is operating exactly as it should. I also have a newer hp 35s which operates exactly the same way.

If you set the display to FIX 03, it will FIX the decimal places to always show 3. But that isn't how ENG and SCI mode works. What does this mean then: ENG 03? It means it will display 3 digits after the first digit. It does not mean three decimal places.

You can read the manual for the excellent Free42 PC application which works just like the real calculator (one of which I own) -

2.6.4 The ENG function 
The ENG function puts the calculator in engineering notation. It looks like scientific notation but now
the first number does not need to be between 0 and 1 but can be between 0 and 1000 and the power
will be always 3 manifold (corresponding to the magnitude prefixes such as milli-, micro-, kilo-,
mega-, etc. used in engineering units).  For example: 100 will be represented by 100.E0 in ENG 2
mode while 1000 will be 1.00E3 in the same mode. Why do we get 100.E0 for 100 instead of
100.00E2 in ENG 2 mode? Because the calculator shows in engineering mode the same number of
digits it shows in scientific mode.

https://thomasokken.com/free42/doc/42s.pdf

Corrected: The question was from Zucca Not Neomys Sapiens

And, it dd not show E1 or E2 because engineers use E0, E3, E6 etc.

[Zucca]

EDIT: I have to try when I am home tonight, it looks like they detect my public ip and blocked me out as new user.

It crashed two times on me. I am out, sorry.

[bd139]

I’m all over that.

sips another mouthful of goat blood

Don't you have an order against visiting that petting zoo?

You have to get caught first 

[Robert763]

Added a charge line to my pulser. Next step is working on better shaping of the pulse top....but that's another day's problem. 

Also got a wild pic while experimenting with a long exposure app on my phone. I think the lighting confused it.

Funky !

Can we have a pic with a clean pulse and time base setting so we can measure the rise time ? 

And forgive the stupid newbie question but is a "charge line" ,  not much info online to my dismay. Found " charging line " or "line charging", often not even pertaining to electronics...

What does it consist of, its role and how why did you expect it might modify the rise time (in your last post you said rise time without charge line was irrelevant ) ?  I mean I can see it lengthens the pulse of course, but what's the impact on rise time ?

Thanks ! 

The charge line is simply a coaxial cable where it's capacitance has been used.

Here is my charge line:


This is the schematic of the Jim-Williams fast pulse generator:


C₁ is essentially the capacitance of the coax cable.

HTH

Edit:

Here has somebody made a charge line on the PCB:


Source:
http://www.siliconvalleygarage.com/projects/picosecond-pulser.html

Not quite as simple as that. The point of using a length of coax, instead of a much more compact capacitor, is to make use of the distribution of the charge across time and space to match your required signal. It's moving from using lumped components to distributed components.

Basically, welcome to the weird world of RF where you can make a filter just with copper traces on a board, and a black robe and a chicken/goat sacrificing habit are a necessity.

You beat me to it (been off-line all day due to ISP doing work).
For longer pulses at high power e.g. Radar and lasers, often a lumped component equivilent is used. Called a Pulse Forming Network.
https://www.ga.com/capacitors/pulse-forming-networks

[AVGresponding]

I need to check the OP to be sure, but I don't think we've had "you know you're a TE addict when you use a new toothbrush to clean rusty transistors rather than your teeth".

Tesco website is a bit fooked atm, DDOS? Needed more toothbrushes...   

Had all the topside boards out of the 5245L, gently cleaned (not gently enough, a rusty transistor leg broke, plugging the Metcal in right now), adjusted some clearances (some of those TO-5 case were, shall we say, inadvertently thermally coupled?).
Swapped some display boards around, and as soon as I've fixed that tranny leg on the A18 display board I'll give it a burl.

Who uses their teeth to clean transistors?

Same people that use their teeth to strip wire insulation.

I got cured of that habit as a teenager when I used my teeth to strip a bit of zip cord. Only to find my brother had plugged the other end in to a 240V outlet with out me noticing. 
That hurt 

And your still here to tell the tale, were you standing on a nice thick rubber mat by any chance at the time? 

Nope in my bedroom, standing by the door (behind which was the socket the lead was plugged into. I woke up on the other side of the room with the bitten off end of the zip cord in my mouth. This was mid seventies so wired fuses in the consumer units, RCDs were unheard of.
I was very lucky. I had a sore jaw and could not taste anything for bout a week though.

I sometimes wish I wasn't an only child, then I read something like this and think, nah, it's good...

[Zucca]

Man! 

Calling hp retarded ... them's fightin' words in these parts. 

I mean so close to perfection!
Now I have to use ENG 5 and all is good, I have sometimes two extra decimals I do not need but meeeh....

[mnementh]

Bargain for you guys in the US: https://www.ebay.co.uk/itm/Agilent-E3648A-DC-Power-Supply-Parts-Unit-/184995561039?mkcid=16&mkevt=1&_trksid=p2349624.m46890.l6249&mkrid=711-127632-2357-0

Unregulated output on channel one. I’d buy it if it wasn’t $100 for shipping and customs!

Schematics and service manual http://ridl.cfd.rit.edu/products/manuals/Agilent/power%20supplies/E3646AE2.pdf

Thanks again to bd139 for being a pro-level TEA enabler.

The Agilent E3648A dual-output power supply showed up today. Packaged very well. It's in very good physical condition. It's just as advertised: missing the rubber baby buggy bumpers and channel 1 doesn't work. Channel 2 works great. Fails self test, natch. Looks like nobody's had a go at it yet, so that's a ray of sunshine. I looked for anything that had released the magic smoke and found nothing, so I'll actually have to do some reading and probing and all that electronic-y stuff that everyone around here likes to do.

It's my first Agilent. Build quality is excellent. It's all Nichicon, non-magnetic stainless pozidrive hardware, and modular sub-assemblies. I'll make a separate thread for the repair.

One question: I noticed that it has RIFAs (one 100n X2 and two 1n0 Y2s). The unit is dated 2006, which is before KEMET's acquisition of Evox Rifa. Should I start adding the replacements to my Digi-Key shopping cart, or were the explode-y RIFAs only from the 1960's?

I recently got that 2011 dated E3630A with RIFAs in it. They were removed. You just don’t know 

RIFAs are just like peoples in that respect... Them what's not busy bein' born is busy dyin'."

mnem

[Zucca]

Those calcutators...
Once i was lazy.. oh wait.. once i did not wanted to walk upstair and tried using my wifes HP financial calculator..
she is clearly way smarter than i am.  i am unable to use it.

I am a masochist eng, I love to learn painful, difficult and not intuitive stuff (only to save me 2 seconds sometimes...)
May be it's how my TEA disease is evolving.

[mnementh]

Q: "Shall I replace the RIFAs in this device?"

A: "Is the bear Catholic?"¹


¹Comes from this:
- Is the Pope Catholic?
- Does the bear shit in the forest?

 

Remember to put on your running shoes. You don't have to outrun the bear, you only have to outrun the Pope. 

mnem

[beanflying]

Oh, I "accidentally" acquired a lot of 18 outside micrometers on ebay...

https://www.ebay.co.uk/itm/JOBLOT-18x-MITUTOYO-STARRETT-MOORE-WRIGHT-OUTSIDE-MICROMETERS-TOOLS-/265270785540

That's crazy cheap  Keep a couple and profit from the rest 

[McBryce]

Those calcutators...
Once i was lazy.. oh wait.. once i did not wanted to walk upstair and tried using my wifes HP financial calculator..
she is clearly way smarter than i am.  i am unable to use it.

Oh, wife in finance warning: Make sure she doesn't calculate the return on investment of your TEA, you may get lectured.

McBryce.

[beanflying]

There was a vintage slightly crusty HP current probe available on evilbay in Oz  eBay auction: #165025864057

Here's another one -- not as cheap but still interesting. NAWTS, of course.

There is a big difference between the HP and the Tek (apart from obvious colour and age). The HP is AC only, the Tek is AC and DC.

Which Tek ? 
The infamous P6021 and P6022 current probes are AC only probes also and both can be paired with the Type 134 current probe amp for 50 ohm output.

Apart from not seeing the point of displaying a straight line on a scope I have a pair of nice 6 1/2 digit meters with logging capabilities and a set of really accurate shunts I can probe if needed for DC or near DC that I could easily look at on a scope channel if required.

So call me curious and it has been a while since I added to the TEA toys so I thought I should

DC current probes for scopes are useful for signals below about 20-30Hz. They also let you see combined AC and DC signals. For example bias current and the signal.

As the bottom rated spec on the HP is 50 hz I guess it will go a bit lower so a little testing on arrival I guess and see how it behaves at the lower end.

[mnementh]

   Oh, I "accidentally" acquired a lot of 18 outside micrometers on ebay...

https://www.ebay.co.uk/itm/JOBLOT-18x-MITUTOYO-STARRETT-MOORE-WRIGHT-OUTSIDE-MICROMETERS-TOOLS-/265270785540

holy fucking asscrackers.



mnem
 

[tonyalbus]

Those calcutators...
Once i was lazy.. oh wait.. once i did not wanted to walk upstair and tried using my wifes HP financial calculator..
she is clearly way smarter than i am.  i am unable to use it.

Oh, wife in finance warning: Make sure she doesn't calculate the return on investment of your TEA, you may get lectured.

McBryce.

no questions, no lies. 

[mnementh]

I’m all over that.

sips another mouthful of goat blood

Don't you have an order against visiting that petting zoo?

You have to get caught first     

bd doesn't have to go in person anymore... he contracts the goat-bleeding out to a phone bank in India. While he's not exactly sure it's actually goat blood that gets delivered, he does like the tinge of curry.

mnem
*points to clipboard* Yes, right there under the "Miscellaneous Services" addendum...