Test Equipment Anonymous (TEA) group therapy thread

[Brumby]

Hmmm ... "overkill" ... ??

*looks up dictionary*

  I do not understand.

Overkill -- see appropriate or sufficient.

So, there.

Ah.  Thank you!

Dictionary updated.     

[AVGresponding]

BAH!

Spoke too soon on the EP-613, it started to drift rapidly to the tune of a volt and more shortly after I posted.
It's gonna be a pita to inspect the control board as afaics all the connections are soldered rather than plugged   
Prime suspect has to be a bad solder joint somewhere   


@mnem, this may interest you: 
I was amazed he could achieve the required thrust to weight ratio using all standard parts!   


I see the troll has been banned... I did find a user of the same name posting on some barely frequented AI site, the drawing style matches, as does the meaningless content...

[bd139]

Lots of trolls out there still.

I'm actually surprised lego has enough grunt for that.

[Specmaster]

Early indications are via my lashed up 2.4v mem retention supply is that calibration is fairly easy to do on the 4503 DMM as it allows the correct value to be manually entered via the numerical keypad and stored, the real problem I have to overcome is getting a voltage supply AC and DC in the 4000v range without mega bucks being spent and sliding into that black hole known as the "Rabbit Hole"

[bd139]

Is that actually rated to 4KV? 1KV is probably high end on that range.

You can get close to AC 1KV FSD on those with a 240/24V transformer and a 6/240V transformer back to back. Then compare with a known good meter.

Edit: obvious disclaimer: dangerous. The secondary transformer should be a hi-pot tested one not some random junk box job

[AVGresponding]

Errr... no, the maximum permissible input voltage is 1kV.

Also, you don't need to go all the way to the extremes, it just helps with reducing scaling errors, but 700V or so should be MORE than adequate for that range...


EDIT: 1kv on the DC, 750V on the AC ranges are the maximum permissible.

[Specmaster]

Yep I just realised that the 4000 on the input ranges actually refers to 4,000k and 1,000v max input DC and 700v AC so it's not a major problem after all with a little thought, I can use 230Vac as the input source for both the 400v and the 750Vac ranges and it will be near enough for function. When it comes to DC, I have my Heathkit RC bridge which generates around 360Vdc and by comparing the readings against a known good meter, I can then enter those values into memory and it will fit for my purposes.

I'm going to hold off doing any more calibration on this until the correct battery arrives, hopefully tomorrow, then I can reassemble it correctly with all the proper screening in place and then it should be job done, another British built piece of TE on my bench 

[Mr. Scram]

Don't be mean to him. If he'd bought something that 'just worked' he wouldn't have had to do any tinkering.
If he didn't have any tinkering to do he wouldn't be happy.
If he wasn't off happily tinkering with that printer he'd be getting under our feet.
Therefore the 'cheap' printer was a good thing - Q.E.D.

He's a right little tinker that dragon.

I wasn't trying to be mean. I was just wondering what the score was at this point. I think mnem knew full well he was going into a project and not necessarily going for value for money or ease.

[Cerebus]

Don't be mean to him. If he'd bought something that 'just worked' he wouldn't have had to do any tinkering.
If he didn't have any tinkering to do he wouldn't be happy.
If he wasn't off happily tinkering with that printer he'd be getting under our feet.
Therefore the 'cheap' printer was a good thing - Q.E.D.

He's a right little tinker that dragon.

I wasn't trying to be mean. I was just wondering what the score was at this point. I think mnem knew full well he was going into a project and not necessarily going for value for money or ease.

You've definitely got a wooden ear for humour when the comedy fx aren't present, only implied. Try this:

"[Fx: mocking baby talk voice used for comic effect] Awwww, poor widdle dwagon. Don't be mean to him. "

Better? I can see that I'm going to have to telegraph the joke in future if I want you to get it, which I hate having to do.

[AVGresponding]

Different nationalities often have difficulty understanding each others humour.

Sometimes it only translates when you know the other person quite well.

[Cerebus]

Is that actually rated to 4KV? 1KV is probably high end on that range.

You can get close to AC 1KV FSD on those with a 240/24V transformer and a 6/240V transformer back to back. Then compare with a known good meter.

Edit: obvious disclaimer: dangerous. The secondary transformer should be a hi-pot tested one not some random junk box job

I've got an UltraVolt 1kV adjustable DC to DC converter brick sitting around that I've been meaning to put into a box with a control pot to use as a short term transfer standard for DC measurements on that kind of scale. They go quite cheaply on fleaBay and some go up to 4kV output voltage. Typically 6V or 12V input, a few mA out.

[bd139]

I have actually considering building one. I like designing and building switching building power supplies.

[BU508A]

It is not only about nationalities. It depends also on the people involved as well.
I know people which cannot understand sarcasm. For me as a person which likes
to be sarcastic (or ironic) it is hard to supress a sarcastic (ironic) comment.
I caused this way in the past lots of heated arguments. 

[Cerebus]

Different nationalities often have difficulty understanding each others humour.

Sometimes it only translates when you know the other person quite well.

Not a language problem here, Le Scram is a native English speaker. It's not the first time he's missed the joke and taken me at face value; it's just that I hadn't realised in any kind of systematic way that, in this one respect, he's a bit slow on the uptake. Not a problem, I'll just have to try to remember it when I'm replying to him that he may not get the joke immediately and modify my style.

[BU508A]

I have actually considering building one. I like designing and building switching building power supplies.

But >= 1kV? I thought, you are trying to stay away from such high voltages as far as you can?
Aren't you the <40V fan?   

[AVGresponding]

It is not only about nationalities. It depends also on the people involved as well.
I know people which cannot understand sarcasm. For me as person which likes
to be sarcastic (or ironic) is it hard to supress a sarcastic (ironic) comment.
I caused this way in the past lots of heated arguments. 

I have found British and German humour to share quite a bit of common ground; we even stole one of your words for it, "schadenfreude" (I only admit to enjoying it for comic effect    ).

[Cerebus]

It is not only about nationalities. It depends also on the people involved as well.
I know people which cannot understand sarcasm. For me as person which likes
to be sarcastic (or ironic) is it hard to supress a sarcastic (ironic) comment.
I caused this way in the past lots of heated arguments. 

Now, I've never detected a note of sarcasm in anything you say, not at all, not once. You use sarcasm almost as rarely as I do.

[Cerebus]

I have found British and German humour to share quite a bit of common ground; we even stole one of your words for it, "schadenfreude" (I only admit to enjoying it for comic effect    ).

"schadenfreude" - German for "Boris Johnson has contracted Covid-19".

[bd139]

I have actually considering building one. I like designing and building switching building power supplies.

But >= 1kV? I thought, you are trying to stay away from such high voltages as far as you can?
Aren't you the <40V fan?   

Yes I can handle something that high up if it is constructed to my own safety standards. Talking of which I need to buy a high pot tester at some point.

Looking on eBay now hahaha  . Looks like some of the cheaper insulation testers may do the job but 2kv would be nice.

[BU508A]

It is not only about nationalities. It depends also on the people involved as well.
I know people which cannot understand sarcasm. For me as person which likes
to be sarcastic (or ironic) is it hard to supress a sarcastic (ironic) comment.
I caused this way in the past lots of heated arguments. 

Now, I've never detected a note of sarcasm in anything you say, not at all, not once. You use sarcasm almost as rarely as I do.

Well. Since I am not a native english speaker, I'm very catious about using sarcasm. In this medium here (forum) the non-verbal channel is missing. It is much easier e.g. on the TEA discord sessions.
And another point is: I know most people here only from what they are writing, some from discord and very rare face-to-face.
Same goes the other way around. The people here just see only a very little piece of my personality.

[med6753]

The 8505A is now ready for use. I checked and as required set the absolute zero on the Ohms ranges. I now have a more accurate DMM to set up and adjust the 190mV, 1.9V, and 19V transfer standards for other DMM's requiring them for calibration.

Venturing into 6.5 digit territory wasn't too painful after all.   

[bd139]

and so it begins 

[mnementh]

BAH!

...@mnem, this may interest you: 



I was amazed he could achieve the required thrust to weight ratio using all standard parts!   

...I'm actually surprised lego has enough grunt for that.

LOL.... well, there's more than a little "overkill" <~~~(Brumby, please note correct usage in a sentence here ) going on here. The controllers Lego makes for these motor modules have a max 10.5Vcc input; based on that I'd guess the motors are wound for ~12V to allow some wiggle room with a 4-6 AA cell pack. The guy is overdriving them a WEE BIT <~~~(note sarcastic tone here) at 33-38V. I really was just waiting for the poor thing to drop out of the sky with motor modules on fire.    My guess is the only reason that didn't happen is the limited amount of current you can draw from a 200mAH cell through that LEGO ribbon cable. 

I was originally wondering why he went the FC/PWM-homebrew MOSFET ESC route; the high operating voltages are the reason. We have FCs with brushed controllers built-in, but they're typically designed for 3S (11.1-12.8V) max. That setup with PWM signal to a MOSFET is how we used to do things back in the stone-age; it results in very slow response times to the PID loops which is why the poor thing was so squirrely.

But HUGE KUDOS to the guy for starting out and following through on this very LEGO experiment. 

mnem
Too much is NEVER enough.

[bd139]

The lego motors of my era were quite robust in that respect. I refer to these ones:



I managed to use two isolated model railway controllers in series to get around 25V out. It was quite happy for a while just made screaming noises! Not bad for 4.5V rated  . They did lose a bit of torque once you'd done that, I assume due to the molten things that remained where the brushes were. 

[mnementh]

Here's version two of my DER expansion after all modifications were made, the part needs just minor sanding after printing. In black this time, because that looks sexier (and @mnementh, the carbon used to make PLA black will add additional screening from the ether, sunspots and the gravitational pull of Mars ).

@worsthorse: Attached are the three models (in TL-24.zip), Type-A is a blank case with no holes to make your own type, Type-B has the 4 BNC sockets with anti-rotation feature and the Lid file fits on both versions. I would advise others to add some support blockers to minimise the supports to the centre of the model, otherwise it's quite a bit of work to remove the support frame from within the box. On an Ender 3 Pro at 0,2mm the main case takes about 4.5 Hours, the lid takes just over an hour to make.

McBryce.

A delightful level of overkill which of course we know there is no such thing as we are here after all with far to much gear for the job at hand

Agreed! Well-done; great follow-through. We all eagerly await your empirical testing. 

I really am surprised you didn't bring the BNCs out the sides; this would naturally segregate the leads by connection and not make the leads kink against the benchtop when you have the meter upright on its bail. That is what I had in mind with my own PCB design scribbled on a napkin here somewhere; the layout of the connections to the sockets tends to lend itself to this configuration as well.

mnem