Test Equipment Anonymous (TEA) group therapy thread

[med6753]

Seriously? £80?

https://www.ebay.co.uk/itm/384932494888

Seriously, a wet dream on his part.  Bids should have started at $40 USD at most.

And then you have to modify the unregulated +5V supply for better stability. Once that's done it is a damn good DMM.

[bd139]

Seriously? £80?

https://www.ebay.co.uk/itm/384932494888

Seriously, a wet dream on his part.  Bids should have started at $40 USD at most.

And then you have to modify the unregulated +5V supply for better stability. Once that's done it is a damn good DMM.

It's a terrible DMM full stop. Apart from the 5V problem it has mains routed badly on the main board, the display design and assembly stinks, the rest of the power supply stinks and the front end protection stinks.

[mansaxel]

Digi:

mnem
No relation.

That guy is/was  the lead maintainer for Hercules, the System 360/370/zSeries emulator.  I actually came across him because of that, not because the suit; the Other Hobby was sort of an added bonus.  I never was a cosplay person, nor a furry; the closest I've come to any such scene is that gig with the soap bubble machine in Karlstad, back in '94.... 

[med6753]

Seriously? £80?

https://www.ebay.co.uk/itm/384932494888

Seriously, a wet dream on his part.  Bids should have started at $40 USD at most.

And then you have to modify the unregulated +5V supply for better stability. Once that's done it is a damn good DMM.

It's a terrible DMM full stop. Apart from the 5V problem it has mains routed badly on the main board, the display design and assembly stinks, the rest of the power supply stinks and the front end protection stinks.

Mains routed badly? Yes, compared to today's more safety conscious designs. Don't go sticking your fingers where they don't belong.   

Display and assembly design? Meh....it's OK.

Shitty PSU? Agreed. My redesign addresses all the issues.

Lousy front end protection? Seems acceptable.

   

[xrunner]

So the last thing I need for this PC is a Ryzen 5 5600G. I put it in my Amazon "Shopping List" (not the cart) last week, and the price keeps creeping down and down. It's -5% from the time I added it last week. I think their AI does it to entice you to buy things. Wonder how much lower it'll go?

Anyway, that'll be the last computer upgrade I'll ever need to do.

 

I remember a long time ago (latter 1980s) I got a 20 MHz 386 computer, it was the latest and greatest thing around. Friends were telling me I was nuts to buy such a powerful PC. Why, I'd never need that much computing power, what a waste of money! Wish they were standing here now.

The actual 386 20 MHz CPU I had back then, that I still have, is shown in the pic just taken. 20 MHz - and now we have multi-GHz clocks. 20 MHz seems almost prehistoric. Wonder what we'd be doing now with our PCs if for some reason they were never able to make CPUs with much higher clocks, say maybe 200 MHz was the limit they ran into. I bet software would be a whole lot more efficiently written. Heck we got to the Moon with a lot less computing power than a 20 MHz 386 CPU.

[bd139]

So the last thing I need for this PC is a Ryzen 5 5600G. I put it in my Amazon "Shopping List" (not the cart) last week, and the price keeps creeping down and down. It's -5% from the time I added it last week. I think their AI does it to entice you to buy things. Wonder how much lower it'll go?

Anyway, that'll be the last computer upgrade I'll ever need to do.

 

I remember a long time ago (latter 1980s) I got a 20 MHz 386 computer, it was the latest and greatest thing around. Friends were telling me I was nuts to buy such a powerful PC. Why, I'd never need that much computing power, what a waste of money! Wish they were standing here now.

The actual 386 20 MHz CPU I had back then, that I still have, is shown in the pic just taken. 20 MHz - and now we have multi-GHz clocks. 20 MHz seems almost prehistoric. Wonder what we'd be doing now with our PCs if for some reason they were never able to make CPUs with much higher clocks, say maybe 200 MHz was the limit they ran into. I bet software would be a whole lot more efficiently written. Heck we got to the Moon with a lot less computing power than a 20 MHz 386 CPU.

Bit difficult posting on instagram with a 20MHz 386 

I find the desktop PC market to be the least insane progress. The smart devices is where it gets weird. My watch is a dual 1.8GHz 64-bit RISC CPU with 1GB of RAM and 32GB of storage with 2x 2.4GHz radios, 1x 5GHz radio, 1x 60GHz radio, 4x GPS receivers and a whole bunch of environmental and contact sensors. And the battery lasts a good couple of days

[bd139]

Seriously? £80?

https://www.ebay.co.uk/itm/384932494888

Seriously, a wet dream on his part.  Bids should have started at $40 USD at most.

And then you have to modify the unregulated +5V supply for better stability. Once that's done it is a damn good DMM.

It's a terrible DMM full stop. Apart from the 5V problem it has mains routed badly on the main board, the display design and assembly stinks, the rest of the power supply stinks and the front end protection stinks.

Mains routed badly? Yes, compared to today's more safety conscious designs. Don't go sticking your fingers where they don't belong.   

Display and assembly design? Meh....it's OK.

Shitty PSU? Agreed. My redesign addresses all the issues.

Lousy front end protection? Seems acceptable.

   

Now that is a proper power supply design. I am satisfied 

As for the front end, there basically isn't any protection at all

[xrunner]

So the last thing I need for this PC is a Ryzen 5 5600G. I put it in my Amazon "Shopping List" (not the cart) last week, and the price keeps creeping down and down. It's -5% from the time I added it last week. I think their AI does it to entice you to buy things. Wonder how much lower it'll go?

Anyway, that'll be the last computer upgrade I'll ever need to do.

 

I remember a long time ago (latter 1980s) I got a 20 MHz 386 computer, it was the latest and greatest thing around. Friends were telling me I was nuts to buy such a powerful PC. Why, I'd never need that much computing power, what a waste of money! Wish they were standing here now.

The actual 386 20 MHz CPU I had back then, that I still have, is shown in the pic just taken. 20 MHz - and now we have multi-GHz clocks. 20 MHz seems almost prehistoric. Wonder what we'd be doing now with our PCs if for some reason they were never able to make CPUs with much higher clocks, say maybe 200 MHz was the limit they ran into. I bet software would be a whole lot more efficiently written. Heck we got to the Moon with a lot less computing power than a 20 MHz 386 CPU.

Bit difficult posting on instagram with a 20MHz 386 

I find the desktop PC market to be the least insane progress. The smart devices is where it gets weird. My watch is a dual 1.8GHz 64-bit RISC CPU with 1GB of RAM and 32GB of storage with 2x 2.4GHz radios, 1x 5GHz radio, 1x 60GHz radio, 4x GPS receivers and a whole bunch of environmental and contact sensors. And the battery lasts a good couple of days

Interesting -

The latest USB-C chargers are apparently more powerful than Apollo 11’s computer

[med6753]

As for the front end, there basically isn't any protection at all

I yield to your assessment. Yep, basically none. Q1 is very much left exposed. I was thinking of other Flukes.

I still think it's a decent and accurate 3.5 DMM if the PSU is rebuilt.

[Specmaster]

Seriously? £80?

https://www.ebay.co.uk/itm/384932494888

Interestingly, they also claim that it is fully functional and working, then they say they don't have a power cable so unable to test it. Run folks, they are just relying on the good name of Fluke to make a quick buck. 

[AVGresponding]

That digimess stuff is Chinese rebrand garbage. Not even decent Chinese garbage but rock bottom stuff 

Some of it might be, idk I've not had any in my hands. This however, does not look like Chinese made, it looks low volume, low R&D budget, low design budget, mid-quality euro-tryhard. In fact, it reminds me of early TTi stuff.  https://www.ebay.co.uk/itm/234578724312



It's from rchaudio so it's overpriced. Just to prove the Grundig lineage: https://www.farnell.com/datasheets/104629.pdf

I'd pay £50 shipped.

[AVGresponding]

So for months now I have been watching ePay for a good deal on a Tek THS720 or 730 scope.  I want one with isolated channels so I can watch both windings of a bipolar stepper motor or put one channel on a motor on an H-bridge while monitoring logic that drives the H bridge on the other channel.  So today I came across this listing.  Looks like it comes with a rather interesting power line monitoring probe. 

https://www.ebay.com/itm/115387055667

That seems horrifically expensive. The three THS720's I bought over the last year or so ranged from £100 to just under £200. That's ~$125-$250.

[AVGresponding]

Seriously? £80?

https://www.ebay.co.uk/itm/384932494888

Seriously, a wet dream on his part.  Bids should have started at $40 USD at most.

And then you have to modify the unregulated +5V supply for better stability. Once that's done it is a damn good DMM.

It's a terrible DMM full stop. Apart from the 5V problem it has mains routed badly on the main board, the display design and assembly stinks, the rest of the power supply stinks and the front end protection stinks.

So, when are you buying it?   

[BU508A]

So for months now I have been watching ePay for a good deal on a Tek THS720 or 730 scope.  I want one with isolated channels so I can watch both windings of a bipolar stepper motor or put one channel on a motor on an H-bridge while monitoring logic that drives the H bridge on the other channel.  So today I came across this listing.  Looks like it comes with a rather interesting power line monitoring probe. 

https://www.ebay.com/itm/115387055667

The BNC connectors are looking a bit worn out. Not unusual for this scope.


The battery (NiCd iirc) is very likely dead and should be replaced. it is located behind this round lid.
Replacements for the battery seems to be available, but not for cheap.

The Firmware shown in the picture is v. 1.03. The latest (and last) official release was v. 1.16 I recommend to update the firmware.
Source:
https://forum.tek.com/viewtopic.php?t=138280

Thanks to Zucca, you can find a lot of information and the v. 1.16 Firmware here:
https://www.eevblog.com/forum/testgear/tek-ths720a-portable-scope-teardowndiscussion/

[Neomys Sapiens]

I was limiting the list intentionally at 3-terminal ones. Otherwise I would have not only included the L200, but also the LM104, LM106, LM2991, LR8K4, SG1501, SG1532, ....
LM150/250/350 is a 3A adjustable between the 117 and the 138.

That's an interesting one!
I've attached the datasheet of it. Is there a similar one of the SG1501A from Linear Technology?

Nope. The only similar part that I know of is the RC4194 from Raytheon, which came in a D14 too, but also in a 9-pin TO-66 outline. Second sourced by Exar as XR4104 (D14 only).

[bd139]

Seriously? £80?

https://www.ebay.co.uk/itm/384932494888

Seriously, a wet dream on his part.  Bids should have started at $40 USD at most.

And then you have to modify the unregulated +5V supply for better stability. Once that's done it is a damn good DMM.

It's a terrible DMM full stop. Apart from the 5V problem it has mains routed badly on the main board, the display design and assembly stinks, the rest of the power supply stinks and the front end protection stinks.

So, when are you buying it?   

Had one. Hated it.

Quite happy with the 3465A. It’s 4.5 digits as well 

[mnementh]

mnem
No relation.

That guy is/was  the lead maintainer for Hercules, the System 360/370/zSeries emulator.  I actually came across him because of that, not because the suit; the Other Hobby was sort of an added bonus.  I never was a cosplay person, nor a furry; the closest I've come to any such scene is that gig with the soap bubble machine in Karlstad, back in '94....

I made that particular version like 15 years ago after seeing a really hatefully vandalized version of the original "I'm from the Internet" meme, and literally not being able to find anything left that hadn't been so defaced that I could use.  It took off again for a few days; no idea how much circulation as I anon-published.



Saw this from KnowYourMeme while I was trying to find that version again; I only knew what I'd read about it all from /. back in the day. You go, old man!

mnem
 

[Carl_Smith]

So for months now I have been watching ePay for a good deal on a Tek THS720 or 730 scope.  I want one with isolated channels so I can watch both windings of a bipolar stepper motor or put one channel on a motor on an H-bridge while monitoring logic that drives the H bridge on the other channel.  So today I came across this listing.  Looks like it comes with a rather interesting power line monitoring probe. 

https://www.ebay.com/itm/115387055667

That seems horrifically expensive. The three THS720's I bought over the last year or so ranged from £100 to just under £200. That's ~$125-$250.

I've been watching for months and I've seen only a few go for $250 or less, and those were just the scope, and weren't in great condition.   Saw a couple go for around $150 and they were listed as non working for parts only and looked like they had been drug behind a truck for a few hundred miles.

I wasn't really considering that one in particular, I just thought the scope probe wired into a mains plug was an interesting accessory.   

Since I've been watching, it seems if you want one that is shown powered on and working, comes with at least probes and most of the accessories like the serial cable and maybe a somewhat working battery, you are looking at well over $300.

[factory]

Seriously? £80?

https://www.ebay.co.uk/itm/384932494888

Seriously, a wet dream on his part.  Bids should have started at $40 USD at most.

And then you have to modify the unregulated +5V supply for better stability. Once that's done it is a damn good DMM.

It's a terrible DMM full stop. Apart from the 5V problem it has mains routed badly on the main board, the display design and assembly stinks, the rest of the power supply stinks and the front end protection stinks.

So, when are you buying it?   

Strangely there is one that is functioning for slightly less money, including shipping & taxes from the US, has the same low ohm option too. 


And no I don't want it either.
https://www.ebay.co.uk/itm/144587432618

David

[Vince]

Shitty PSU? Agreed. My redesign addresses all the issues.


   

Papa Smurf I am wondering, about the 5V rail redesign.

I am wondering why you didn't simply add the 7805 and call it a day ?

You replaced the original two-diode / center tap full rectification with a full bridge diode, which forced you to use only one of the two windings.
So now that winding has to supply twice the current it was designed for, no ? I am sure it works fine in this particular case since you did it, but you didn't know it could take it... it might overheated and blew a head gasket or something.... at the least it's way overloaded so it's not being nice to him.

Also, you halved the value of the capacitor, so more ripple. The 7805 is probably able to make up for that, but why not just leave the cap at its original value ?!

Why not have simply kept everything original hence safe (for the transformer windings) and in spec (ripple wise), i.ie simply leave the center full wave rectification and 4000uF cap in place, and simply add your 7805 after that ?! 

[med6753]

Seriously? £80?

https://www.ebay.co.uk/itm/384932494888

Seriously, a wet dream on his part.  Bids should have started at $40 USD at most.

And then you have to modify the unregulated +5V supply for better stability. Once that's done it is a damn good DMM.

It's a terrible DMM full stop. Apart from the 5V problem it has mains routed badly on the main board, the display design and assembly stinks, the rest of the power supply stinks and the front end protection stinks.

So, when are you buying it?   

Strangely there is one that is functioning for slightly less money, including shipping & taxes from the US, has the same low ohm option too. 


And no I don't want it either.
https://www.ebay.co.uk/itm/144587432618

David

That's a more reasonable price and about what I paid for mine. First encountered an 8000A in 1975 as it was the required DMM to set the MST logic voltages (+1.250V and -3.00V) in IBM system's test for the S370 Model 3158. Was also used to set positive and negative 2% bias to stress the logic and shake out any weak logic cards. They stood up to day to day production banging around very well and I never ran across a defective one. 

[mnementh]

Strangely there is one that is functioning for slightly less money, including shipping & taxes from the US, has the same low ohm option too.     
And no I don't want it either.      https://www.ebay.co.uk/itm/144587432618

David

I guess I've been spoiled by my 3478A and my 189...? No interest whatsoever. Actually, this one had me looking twice, cuz GPIB mine doesn't have and currently only a $50 gamble...

   https://www.ebay.com/itm/115406919620

Yeah, yeah, I see the crunk LCD and g'rilla abuse. I also see one cal seal probably intact. It would also be a great lab rat to try my hand at a BL mod.

mnem
*wibble*

[bd139]

Strangely there is one that is functioning for slightly less money, including shipping & taxes from the US, has the same low ohm option too.     
And no I don't want it either.      https://www.ebay.co.uk/itm/144587432618

David

I guess I've been spoiled by my 3478A and my 189...? No interest whatsoever. Actually, this one had me looking twice, cuz GPIB mine doesn't have and only a $50 gamble...

   https://www.ebay.com/itm/115406919620

Yeah, yeah, I see the crunk LCD and g'rilla abuse. I also see one cal seal probably intact. It would also be a great lab rat to try my hand at a BL mod.

mnem
*wibble*

That is, erm, knackered. I would possibly pay £20 for one like that here. Mostly for parts.

[med6753]

Shitty PSU? Agreed. My redesign addresses all the issues.


   

Papa Smurf I am wondering, about the 5V rail redesign.

I am wondering why you didn't simply add the 7805 and call it a day ?

You replaced the original two-diode / center tap full rectification with a full bridge diode, which forced you to use only one of the two windings.
So now that winding has to supply twice the current it was designed for, no ? I am sure it works fine in this particular case since you did it, but you didn't know it could take it... it might overheated and blew a head gasket or something.... at the least it's way overloaded so it's not being nice to him.

Also, you halved the value of the capacitor, so more ripple. The 7805 is probably able to make up for that, but why not just leave the cap at its original value ?!

Why not have simply kept everything original hence safe (for the transformer windings) and in spec (ripple wise), i.ie simply leave the center full wave rectification and 4000uF cap in place, and simply add your 7805 after that ?! 

There was insufficient voltage "headroom" from the transformer to allow the 7805 to regulate. That circuit as it was originally configured was only about +4.7V at the 4000uf capacitor.

The 2200uf capacitor was what I had on hand at the time and decided to run with it. No ripple issues.   

Before the mod the 8000A would drift quite a few mV while warming up. After the mod there was no appreciable drift.

[mnementh]

I guess I've been spoiled by my 3478A and my 189...? No interest whatsoever. Actually, this one had me looking twice, cuz GPIB mine doesn't have and only a $50 gamble...

   https://www.ebay.com/itm/115406919620

Yeah, yeah, I see the crunk LCD and g'rilla abuse. I also see one cal seal probably intact. It would also be a great lab rat to try my hand at a BL mod.

mnem
*wibble*

That is, erm, knackered. I would possibly pay £20 for one like that here. Mostly for parts.

Errmmm... exactly what I'm looking at. 20 quid is ~$25... and then I have to pay to get it here. 

These are a effing big and heavy chunk of iron compared to the front panel size, dood... but I don't have to tell you that. Ain't no way in 'ell that's fitting in a flat-rate box.

Also, I said "looking twice...", not   

mnem