Test Equipment Anonymous (TEA) group therapy thread

[tggzzz]

For when you need to measure your tzzzzzt:  https://www.ebay.co.uk/itm/255592412251

I have a P6013 that I ought to sell (since I've also got a P6015).

The bad thing with the P6015 is that it has to be filled with FREON and that is almost unobtanium
The P6015A is gel filled and last forever, if treated well.

Yes and no. You only need the CFC to reach the full voltage rating. It is specified for a lower voltage without the CFC.

Mine still has a little fluid inside it, which is theoretically sufficient to maintain the necessary vapour pressure. If it really is CFC, of course!

EDIT: P6013 is 12kV to 100kHz, P6015 is 20kV to 100kHz, or 13kV to 500kHz without CFC filling

[Vince]

Those DC converters need a load to stop them oscillating frantically. I did some tests on some ages ago. Surprisingly I couldn't murder them!

Yeah  I tried with no load first, because the info I found on a French Amazon ad selling these boards, stated that the ripple was 30mVpp with NO lad.
So I was trying to test for that...

OK so I added some load to see what would happen.

First a 1k resistor, so about 10mA load. Frequency goes from 40HZ up to 1kHz, much better, but ripple remains unchanged at a massive 2Vpp.

So I increased the load to 100mA, 10 times more. Put a beefy 100R resistor I had in stock.

Ah OK there is change now. Frequency goes up to 100kHz or so, and ripple calsm down at last, now "only" 200mVpp. Still huge but hey, 10 times better than before ! 

Then I doubled the load, added another 100R resistor.. no change in frequency nor ripple amplitude.

Then I added a 10uF cap at the output. NO change what-so-ever. Yes, the cap is good, I tested it prior ! 

Then I RTFM the datasheet... the frequency "problem" is not a problem, it's a FEATURE ! 

Datasheet explains that OK, with a resistor you set the switching frequency BUT, in order to improve efficiency, the chip will automatically LOWER the frequency more and more, as the load becomes lighter and lighter !  Says it will only use the max set frequency for "moderate to full loads". No, they don't define what "moderate" means... but it's easy enough to measure I guess.

OK so the super low frequency at llght loads was normal.... what is not normal is the massive ripple and the fact even a big 10uF cap does not provide any reduction whatsoever...

Will try another board to see if the ripple is as bad...

[bd139]

Well it's a switching converter so you sort of expect that.

Better a Royer converter or something if you want less noise.

[Specmaster]

<snip>
AirPods pro with transparency mode on. Also works for the idiots when you get out of the car as you can turn on noise cancellation mode 

Not so sure that they are allowed to be used while driving, certainly not worth the hassle of trying to explain to traffic cops that you can still hear emergency two tone horns and other shit.

Fair points. I don't drive with them in as I quite like offensively loud music so I can't hear the two tone horns either 

I can join you on that point, I love to play my stereo loud and soak in all that lovely sound quality 

[mnementh]

*puts hand up to ear*   "WHAAAAAAAT?!?"

mnem
thump.

[med6753]

<snip>
AirPods pro with transparency mode on. Also works for the idiots when you get out of the car as you can turn on noise cancellation mode 

Not so sure that they are allowed to be used while driving, certainly not worth the hassle of trying to explain to traffic cops that you can still hear emergency two tone horns and other shit.

Fair points. I don't drive with them in as I quite like offensively loud music so I can't hear the two tone horns either 

I can join you on that point, I love to play my stereo loud and soak in all that lovely sound quality 

I rarely listen to music while driving. I find it too distracting. I much prefer to be fully alert for hazards as well as concentrate on the main objective: driving. 

[Specmaster]

UK weather report said that there is high chance of thunderstorms for the southeast and the first lightening strike has just been recorded at Stratford St Andrew in Suffolk and another near Ashford in Kent, but the main storm is currently still over in Belgium, so will we get a storm or not?

https://www.lightningmaps.org/?lang=en#m=oss;t=3;s=0;o=0;b=0.00;ts=0;z=6;y=49.9066;x=3.5287;d=2;dl=2;dc=0;

[med6753]

*puts hand up to ear*   "WHAAAAAAAT?!?"

mnem
thump.

Just today I'm coming up my road and there is a kid on a bicycle going in my direction in the middle of the road. I slowed and figured he would hear my approach. Nope. I had to come almost to a complete stop and decided I had no choice but to lay on the horn. Only then did he turn around and realize I was there and moved over. And then I saw that the jerk had earbuds on.   

[bd139]

UK weather report said that there is high chance of thunderstorms for the southeast and the first lightening strike has just been recorded at Stratford St Andrew in Suffolk and another near Ashford in Kent, but the main storm is currently still over in Belgium, so will we get a storm or not?

https://www.lightningmaps.org/?lang=en#m=oss;t=3;s=0;o=0;b=0.00;ts=0;z=6;y=49.9066;x=3.5287;d=2;dl=2;dc=0;

I fucking hope not. It better not shit it down for Newbury on Sunday.

[med6753]

UK weather report said that there is high chance of thunderstorms for the southeast and the first lightening strike has just been recorded at Stratford St Andrew in Suffolk and another near Ashford in Kent, but the main storm is currently still over in Belgium, so will we get a storm or not?

https://www.lightningmaps.org/?lang=en#m=oss;t=3;s=0;o=0;b=0.00;ts=0;z=6;y=49.9066;x=3.5287;d=2;dl=2;dc=0;

Are thunderstorms that rare in the UK? Damn near once or sometimes twice a week here in the Summer.

[bd139]

<snip>
AirPods pro with transparency mode on. Also works for the idiots when you get out of the car as you can turn on noise cancellation mode 

Not so sure that they are allowed to be used while driving, certainly not worth the hassle of trying to explain to traffic cops that you can still hear emergency two tone horns and other shit.

Fair points. I don't drive with them in as I quite like offensively loud music so I can't hear the two tone horns either 

I can join you on that point, I love to play my stereo loud and soak in all that lovely sound quality 

I rarely listen to music while driving. I find it too distracting. I much prefer to be fully alert for hazards as well as concentrate on the main objective: driving.

I think my choice of music reflects my driving

[mnementh]

*puts hand up to ear*   "WHAAAAAAAT?!?"

mnem
thump.

Just today I'm coming up my road and there is a kid on a bicycle going in my direction in the middle of the road. I slowed and figured he would hear my approach. Nope. I had to come almost to a complete stop and decided I had no choice but to lay on the horn. Only then did he turn around and realize I was there and moved over. And then I saw that the jerk had earbuds on.   

Earbuds are for people too stupid to destroy their hearing properly; that is, with megatons of MEBBs and speakers so tall that dusting them gives you a nosebleed. 

mnem
vroom.

[Cubdriver]

3/ The two large wires connected together are the CPC (earth) and Netural. A connection which according to some does not exist.

I am not sure of the Canadian and USA differences, but my understanding for the GWN is that those are to be connected together in only one specific location, done by the electricity utility company.
Anything done within the house at or after the main panel shall not have the Earth and Neutral connected together.

Two reasons I can think of:
- no ground loop current
- correct functioning of GFCI protection

As for unused conductors; we are too cheap in the GWN to allow that situation to ever occur...  my vague recollection of the rule is that it is such a major PITA to be avoided at all cost.

Here in the US, the ground and neutral are typically bonded together at the main service panel (if it's within a certain distance, five feet IiRC) from the service entrance.  If the cable run within the dwelling is longer than five feet, then an external disconnect must be used (can’t have too much essentially unfused feed line inside), and the neutral and ground are bonded there in the external disconnect location.  In most installations, the meter box is on the outside of a wall and the panel on the inside back to back, so they’re for all intents and purposes directly connected.  As my panel is remote from the service entrance, I needed to buy a $$pecial meter box with a built in breaker, and run the two hots and ground (4/0 wire) and a neutral (3/0 wire) inside through conduit to my main breaker box, which in this instance is treated as a sub panel with separate neutral and ground busses.

-Pat

[mnementh]

I think my choice of music reflects my driving

mnem
shhhhhh! polly-ticks!

[med6753]

<snip>
AirPods pro with transparency mode on. Also works for the idiots when you get out of the car as you can turn on noise cancellation mode 

Not so sure that they are allowed to be used while driving, certainly not worth the hassle of trying to explain to traffic cops that you can still hear emergency two tone horns and other shit.

Fair points. I don't drive with them in as I quite like offensively loud music so I can't hear the two tone horns either 

I can join you on that point, I love to play my stereo loud and soak in all that lovely sound quality 

I rarely listen to music while driving. I find it too distracting. I much prefer to be fully alert for hazards as well as concentrate on the main objective: driving.

I think my choice of music reflects my driving

I don't need music to encourage my road rage. I do quite well all on my own. 

BTW....cool tune. 

[Cubdriver]

*puts hand up to ear*   "WHAAAAAAAT?!?"

mnem
thump.

Just today I'm coming up my road and there is a kid on a bicycle going in my direction in the middle of the road. I slowed and figured he would hear my approach. Nope. I had to come almost to a complete stop and decided I had no choice but to lay on the horn. Only then did he turn around and realize I was there and moved over. And then I saw that the jerk strong Darwin Award candidate had earbuds on. 

Fixed that for you.   

-Pat

[med6753]

*puts hand up to ear*   "WHAAAAAAAT?!?"

mnem
thump.

Just today I'm coming up my road and there is a kid on a bicycle going in my direction in the middle of the road. I slowed and figured he would hear my approach. Nope. I had to come almost to a complete stop and decided I had no choice but to lay on the horn. Only then did he turn around and realize I was there and moved over. And then I saw that the jerk strong Darwin Award candidate had earbuds on. 

Fixed that for you.   

-Pat

He might not have buffed out and I hate damaged sheet metal. 

[Neper]

Just today I'm coming up my road and there is a kid on a bicycle going in my direction in the middle of the road. I slowed and figured he would hear my approach. Nope. I had to come almost to a complete stop and decided I had no choice but to lay on the horn. Only then did he turn around and realize I was there and moved over. And then I saw that the jerk had earbuds on. 

Has he at least shouted at you like this one here?

https://youtu.be/0Xo6NZ7N7I4

[bd139]

If there's one thing I've learned over the years it's that cyclists, pedestrians and drivers are all cunts 

[Vince]

OK past midnight, I gave the board one last try before calling it a day and moving on...

... I increased the load even more, to see if the chip would switch to full frequency and what would become of the ripple. Found a beefy 15W 15R resistor. That increased the load to 600mA or so.

Ripple plummeted ! 

So much so that the fixed x10 Agilent probe that came with the scope, was attenuating a tad too much to zoom on the ripple.
So I replaced it with my usual Tek x1 / x10 probes. Of course doing that limits the B/W to 6 MHz or something, but still good enough to see all the crap coming out of the regulator... no shortage of that for sure.

Ripple as you can see is now only 1mVpp... if you conveniently omit the bursts that contain huge spikes. If you count the spikes then it's more like 5mVpp, which is still very good for a switching anything, especially a cheap one eh ?

So I tried to measure frequency... saying "try" because the waveform looks so noisy, there is no saw tooth to look at any more, it's just noise....  but well, you gotta measure something so....
If I measure between two big bursts, the packets that feature the huge spikes, then I get 100kHz. If I then zoom in to look at the smaller oscillations in between two bursts, then I get 900kHz.. spot on the theoretical switching frequency that we calculated, so that's quite nice. So assuming that's not just luck / coincidence, then that means that all these spiky bursts are at LOWER frequency that the switching frequency ?! How can that be possible ?!  I mean of course I am OK having high frequency parasitic oscillations, but LOWER than the commanded frequency... no I don't quite get it.

So that means instead maybe that the chip at 600mA still is running at 100kHz not 900kHz, and that the 900kHz oscillations we see are just a coincidence... it's nothing to do with the 900kHz we set with that resistor.

Lots of fun.

OK taking everything apart and clearing the bench, more component sorting on the agenda tomorrow...

EDIT : tried to add averaging to clean the signal a bit but jo joy : the deep memory of the Megazoom  makes it a no go : adding even a tiny amount of averaging, lie 4 8 or 16, slows down the redrawing tremendously ! 
With my modest Combiscope and ancient TDS, short memory so I can add LOTS of averaging to clean stuff up really well, with little to no impact on the trace responsiveness. That's great.

So for me at least that's one big problem with the Megazoom, so I am not getting rid of my Combiscope and TDS anytime soon.
Would be nice if the Megazoom allowed you (does it ? Didn't find it in the manual), to disable the deep memory in this particular case.
Also another scenario where the deep memory hurts is refresh rate when trying to find a runt pulse or something. You don't need silly high time resolution to find it, but rather high refresh rates.

I understand the modern scopes allow you to set yourself the trade-off between sampling speed and memory depth which is the best of both worls I guess. The merger between the older scopes, and the Megazoom revolution.

So yeah, I love the Megazoom but I will keep my other scopes as well, I want BOTH  ! 

[tggzzz]

UK weather report said that there is high chance of thunderstorms for the southeast and the first lightening strike has just been recorded at Stratford St Andrew in Suffolk and another near Ashford in Kent, but the main storm is currently still over in Belgium, so will we get a storm or not?

https://www.lightningmaps.org/?lang=en#m=oss;t=3;s=0;o=0;b=0.00;ts=0;z=6;y=49.9066;x=3.5287;d=2;dl=2;dc=0;

I fucking hope not. It better not shit it down for Newbury on Sunday.

Many weather reports are, um, exaggerated clickbait. These are reasonable
https://www.netweather.tv/weather-forecasts/uk/7-day/6170~Chieveley
https://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&amp;MENU=0000000000&amp;CONT=ukuk&amp;MODELL=gfs&amp;MODELLTYP=1&amp;BASE=-&amp;VAR=prec&amp;HH=66&amp;ZOOM=0&amp;ARCHIV=0&amp;RES=0&amp;WMO=&amp;PERIOD=

Currently, at
$ date
Thu Jun 23 23:49:57 BST 2022
there is rain forecast for Brizzle and further north, but Chieveley is OK.  But quite frankly it is too early to forecast that closely. The best techinque is to look every 6hours, and see how much the forecast is changing.

[Specmaster]

*puts hand up to ear*   "WHAAAAAAAT?!?"

mnem
thump.

Just today I'm coming up my road and there is a kid on a bicycle going in my direction in the middle of the road. I slowed and figured he would hear my approach. Nope. I had to come almost to a complete stop and decided I had no choice but to lay on the horn. Only then did he turn around and realize I was there and moved over. And then I saw that the jerk strong Darwin Award candidate had earbuds on. 

Fixed that for you.   

-Pat

He might not have buffed out and I hate damaged sheet metal. 

It'd be alright, just get your hacksaw out again and it will be as if nothing ever happened.

[tggzzz]

UK weather report said that there is high chance of thunderstorms for the southeast and the first lightening strike has just been recorded at Stratford St Andrew in Suffolk and another near Ashford in Kent, but the main storm is currently still over in Belgium, so will we get a storm or not?

https://www.lightningmaps.org/?lang=en#m=oss;t=3;s=0;o=0;b=0.00;ts=0;z=6;y=49.9066;x=3.5287;d=2;dl=2;dc=0;

Are thunderstorms that rare in the UK? Damn near once or sometimes twice a week here in the Summer.

Thunderstorms aren't rare, but they make good clickbait for the remnants of local newspapers. That's because we have weather (not climate), and hence it is a standard default topic of conversation.

[tggzzz]

If there's one thing I've learned over the years it's that cyclists, pedestrians and drivers are all cunts 

Yup.

I carefully taught my daughter that they are all out to kill you, and will succeed if you give them enough chances.

Glider pilots are wonderfully benign by comparison; they are willing to learn from anyone where the lift is at the moment, and they are taught the etiquette of sharing bubbles of hot air.

[mnementh]

OK past midnight, I gave the board one last try before calling it a day and moving on...

... I increased the load even more, to see if the chip would switch to full frequency and what would become of the ripple. Found a beefy 15W 15R resistor. That increased the load to 600mA or so.

Ripple plummeted ! 

So much so that the fixed x10 Agilent probe that came with the scope, was attenuating a tad too much to zoom on the ripple.
So I replaced it with my usual Tek x1 / x10 probes. Of course doing that limits the B/W to 6 MHz or something, but still good enough to see all the crap coming out of the regulator... no shortage of that for sure.

Ripple as you can see is now only 1mVpp... if you conveniently omit the bursts that contain huge spikes. If you count the spikes then it's more like 5mVpp, which is still very good for a switching anything, especially a cheap one eh ?

So I tried to measure frequency... saying "try" because the waveform looks so noisy, there is no saw tooth to look at any more, it's just noise....  but well, you gotta measure something so....
If I measure between two big bursts, the packets that feature the huge spikes, then I get 100kHz. If I then zoom in to look at the smaller oscillations in between two bursts, then I get 900kHz.. spot on the theoretical switching frequency that we calculated, so that's quite nice. So assuming that's not just luck / coincidence, then that means that all these spiky bursts are at LOWER frequency that the switching frequency ?! How can that be possible ?!  I mean of course I am OK having high frequency parasitic oscillations, but LOWER than the commanded frequency... no I don't quite get it.

So that means instead maybe that the chip at 600mA still is running at 100kHz not 900kHz, and that the 900kHz oscillations we see are just a coincidence... it's nothing to do with the 900kHz we set with that resistor.

Lots of fun.

OK taking everything apart and clearing the bench, more component sorting on the agenda tomorrow...

EDIT : tried to add averaging to clean the signal a bit but jo joy : the deep memory of the Megazoom  makes it a no go : adding even a tiny amount of averaging, lie 4 8 or 16, slows down the redrawing tremendously ! 
With my modest Combiscope and ancient TDS, short memory so I can add LOTS of averaging to clean stuff up really well, with little to no impact on the trace responsiveness. That's great.

So for me at least that's one big problem with the Megazoom, so I am not getting rid of my Combiscope and TDS anytime soon.
Would be nice if the Megazoom allowed you (does it ? Didn't find it in the manual), to disable the deep memory in this particular case.
Also another scenario where the deep memory hurts is refresh rate when trying to find a runt pulse or something. You don't need silly high time resolution to find it, but rather high refresh rates.

I understand the modern scopes allow you to set yourself the trade-off between sampling speed and memory depth which is the best of both worls I guess. The merger between the older scopes, and the Megazoom revolution.

So yeah, I love the Megazoom but I will keep my other scopes as well, I want BOTH  ! 

Naaahhh... you're not wrong. Characterizing noise is one of the areas that, IMO, a good analog scope still excels at and in many ways beats out a DSO. In this scenario, it does the averaging by dint of its inherent nature. You don't need the absolute detail that digitizing gives you; you just want to see where the fuzz is thickest and where it ends.

mnem