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Test Equipment Anonymous (TEA) group therapy thread

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That took a while to find in my emails, back in 2013 I bought a full 100m roll of 2183Y three core 0.5mm² mains cable in grey, clearance price was about £18 from Farnell, I dread to think how much it is now.
Some ancient stuff had even thinner mains cables, which seem unavailable now, not that I want any.


m k:
RS has only 2 core 2182y, it's around 90€.

But low and behold, I didn't even bother checking Farnell and they have three different 2183Y versions by metre and more is coming.
Must stop underestimating their need of income.
Their 2183Y-0.5MMGRY100M is around 70€, 2183Y-0.5MMGRY will be around 1€/m.
Some are described as being oval and others round, type is the same, only color is changing.

So now I must start remembering what I forgot ordering last time.
Unfortunately nothing is actually urgent.

Neomys Sapiens:
Oh frabjous day indeed! At least my Multizet A1000 is unreservedly with me again.
All that was needed was to localise the Pot which controls the adjustment range of the front panel electrical zero.
As an added boon, I was able to adjust the AC compensation a bit using the 10kHz output of the DMMcheck.
All ranges consistent and on spot as far as it is discernible on a analogue scala. The totally regular offset over all functions and ranges suggested something like this, but it could also have been some component or, worst case, the movement itself.
Now on to the B1012...which will be harder, I presume.


Electronic Load

Remember that load stroy was originally so that I can test an SMPS ( from a consumer brewing machine) that my old man shipped to me, complaining it would not hold up at large currents.

With the load I proved to him that it worked just fine even at currents much higher than the advertised 5.1A max.

So I shipped it back. He put it back in the machine and... he says it fails again, but when he replaces it with a generic 12 Euros adjustable power brick from Amazon... the machine works fine.

He thinks my FET load is somehow acting wierd, not "resistor like "enough, can't mimic a real load, that it's strange and weird and crap.
So he shipped the SMPS back to me again, along with some wirewound resistors, "real" loads, loads you can trust, in his mind...

So... I tried with his resistors... put x4 6.8R in //, drawing 5,75A, so a lot more than the rated current for this SMPS.... yet it works fine. Output voltage does not drop, and ripple voltage on the scope (yes I went all fancy) is perfectly reasonable and clean.

I don't know what other excuse he will find this time, to say " I did it wrong, it MUST be faulty " .....  :palm:

Anyway, before I tried with his resistors, I first tested it with my load, so I can sweep the current easily and see how it behaves.

So I made a cross of Zoli's SMD PCB load, with Robert's zero Euro load, with the 3 FET's in // on the big heatsink.

At first it did not work, it would not draw any current hmmm.... debug time.
Long story short : one of the op-amp had blown again, was shorting the power supply. Replaced it.
Then the 10V voltage regulator blew too, would give only 300mV output....  I removed it but did not replace it : I bridge its input and output pin so as to bypass it, and replaced the lab pwoer supply with... a 9V battery connector.   This way it's so much easier and tidier on the bench, and does not "waste" a power supply.
A 9V battery I thought, is just fine : the board draws bugger all current. 9V is plenty enough for the 1.25V Vreg chip to work and supply the trim pot.
9V or even 7.5V is the battery is nearly dead... is still plenty enough to drive the gate of the MOSFET and get them to spit bags of current.

So I did that.  Then I replaced the PCB mounted 25 turn tiny trimmer, with my big panel mount x10 turn pot.

Well I was right... it works just fine with the 9V battery and no voltage regulator for the op-amps.

The panel mount pot is so much more comfortable and easier to operate.

It's a winner.

Now that that's out the door, I can resume work on the QUAD amplifiers as I too want to get those out the door fast, so I can start working at long last on my OWN stuff.... stuff I actually care about....

Here's my little take on the load-project. Took some inspiration from what was shown... The "bargraph" is 1A per led, it's just that the puny heatsink (that is on there for now) takes a strong fan to get somewhere even at 5A (of 10). The pin socket provides the shunt amplifier voltage to get it more precise if need be. Just to be clear, I blame you lot for this, dangling the "look how easy this is" and the "look how much use we get out ours" in front of my nose  >:D But honestly, thanks for tempting me - it sure is a nice thing to have!
PS: This post sponsered by "Rome" aka "Star-ground all the things"


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