Test Equipment Anonymous (TEA) group therapy thread

[vk6zgo]

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.

Back when I tried to learn to fly gliders & court SWMBO at the same time (one guess which one missed out!), some of the older club members recalled learning from wedgetailed eagles!

[Cerebus]

*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. 

Today, within 200 yards:

Police car making a three point turn across a busy, narrow, main road while his vision is blocked both ways, including hitting the kerb while he was reversing, this is him hitting the curb



woman on a pushbike stopped inside a traffic light controlled junction to play with her mobile,




man steps out into the road in front of me, without looking, 10 yards from a zebra crossing he could have used instead,



OK, who fitted the idiot magnet to my car?

[TERRA Operative]

What the... hell model of car have you got, then? I thought Volvo was supposed to be a premium brand, and they can't even fit tweeters to all doors and channels  Mine even has mid range and tweeters, woofer at the bottom, mid range in the middle and tweeters right at the top by the door latch. Only 4 pop rivets hold your woofer, did you get any distortion / vibration of the speaker chassis on deep bass as a result of tahat or are your speakers slightly smaller than most, mine had 6 rivets to secure it to the door skin. I should think you certainly notice the extra top end now?

This was, as noted, the bottom rung of the quality ladder. There were several equipment levels available above this; my older cars on the same platform dodid indeed have tweeters, also as noted. Buying a used car you can't be too picky with things like this; I was happy to get the 4WD, large Diesel, semi-leather upholstery version, with hitch and OEM roof rack bars, for a very good price, with a known service record.

The top end is indeed noticeable now!

I put Alpine 3-way splits in my car, made a huge difference to the audio quality.
I spend like 2.5 hours a day in the car commuting in and out of Tokyo, so I wanted some good audio to help me endure the idiots on the road. 

That is the same logic as I applied when I ordered my car, which was at the time a company car. I would often spend upwards of  6 hours at a time in it, so I wanted some good audio and for the times I'd be hanging about in it stuck in jams on the motorways or on site, I also specced the car with a DVD player and TV tuner with surround sound system. Now of course I still get to enjoy all those creature comforts as I brought the car when I retired  That was my plan all along 

We got the big-screen in our car, with TV and DVD, but I never use it as Japanese TV is beyond crap... I got a module installed by the dealer to enable TV while driving too, but only so I could connect my phone through the HDMI port to enable me to screen-share to show Google maps on the screen. (The inbuilt satnav is a little crappy looking, the typically Japanese style of being stuck in 2000's era design, and only in Japanese language).

Usually I just bluetooth my phone to listen to podcasts and music though.

Then I received also today an envelope from Sweden, got RIFA caps to replace the one in the HP scope PSU, and also a set of lovely Hirshcmannnlong grabbers. Sadly the rfd one got broken during transport, sad.... the hard plastic hand piece is badly cracked at the base of the grabber, but still holding together somehow and still works, smoothly at that. It's still perfectly functional. Tried to bend it back into shape / straighten it, no joy, it wants to stay bent, ah well... maybe at least I could fill the gap/crack with super glue ? And maybe add a layer of two of red heat shrink tubing to restore thye electrical insulation ? because having my fingers right on that crack with HV inside the crack does not appeal to me very much, I must confess..

So I replaced that RIFA. PSU board was easy and quickly to remove from the scope. Paid extra attention to plastic rod operating the mains switch, since you said it could break easily... got lucky, it came out and back on, with no drama 

You put a Rifa cap back into the unit!?  I hope you got a late date code on that part............... 

[Cerebus]

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.

Fairly rare, a handful over the summer perhaps. We've had two or three here in my bit of London since the beginning of the year. Depends where you are, when I lived on the south coast they were fairly common, but almost all seemed to happen out to sea.

[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 no joy : the deep memory of the Megazoom  makes it a no go : adding even a tiny amount of averaging, like 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
 

OK this is really startingto bug me now  ! 

I WANT to see that signal better !

I mean, that 900kHz oscillation is spot the theoretical switching frequency of the chip, so assuming that tiny oscillation is indeed that, then it has to be a sawtooth not a sine like it looks like here... I WANT to see the signal better to see if's indeed my sawtooth. That's now my goal in life ! 

So the idea is that maybe it is a sawtooth buty because the probe is set to x1 hence limited to 6MHz or so, it can't passe enough harmonics for a 99kHZ sawtooth hence it looks more like a sine, as we can see.

so I need to use the x10 probe to get the full B/W so that if there is a sawtooth, it can actually SHOW ME a sawxtooth not a sine wave...
So that means I need to amplify the ripple by a factor of 10 to compensate for the x10 attenuation of the probe.  Well x20 or x50 would be better, as currently the ripple is only 1 DIV high, small.

So that's the idea, an excuse to build a little amplifier.

So the specs are, therefore :

- AC coupled, as I am only interested in the ripple
- Small signal, 10mV max at the input, and want ideally x50 so 500mV at the output.
- Output coupling : don't need to be AC coupled, the scopes input can do that...
- Power supply : positive only, for simplicity. Say 12V for the sake of deciding something...
- B/W : a few tens of MHz, so as to be much better than 6MHz of the x1 probe.


Not an amp engineer of course but maybe I can just do a simple single stage amp with a small signal transistor, simple common emitter NPN, like a small class A audio amp. We did that at school to learn the basics... I can do that at least.
12V supply and only 500mVpp at the output, so we are really talking small signal amplification here, hence I guess it's not unreasonable to be able to achieve the ideal x50 amplification I am targeting, with a single stage ? A humble 2N2222A has a transition frequency of 300MHz not bad eh. So how does that work ? It's like op-amp ampliers ? I divide the tgransition frequency by the gain of the amp and that gives me the B/W of the amp ? Roughly ? So if I do a x10 amplification with that 2N2222A, I could hope for 30MHz or so, which would be good I guess, 5 times better than the probe.
x10 is the bare minimum I need. x50 would be ideal. So I could ad another stage with a x5 "gain"/amplification, to get 50 total. Or just spread it evenly between the two and get them both to amplify by a factor of 7 or so.


OK will start working on that, that will be fun, regardless of the outcome and regardless of whether everyone think it's stupid and it's never gonna work.... it's about having some educational fun people, I am not doing this to write PhD thesis eh ?! 

Stay tuned.... 

[TERRA Operative]

If you really want to characterise PSU noise, you need a 60dB amplifier.

https://www.eevblog.com/forum/projects/low-noise-amplifier/

I really should populate my PCB's one day.....

[Vince]

Wow his amp is way too sophisticated for me ! 

Nope, need something quick and dirty, simple. Something I can do with what components I have here, and my limited knowledge acquired at school.

It will have to do.... what comes out comes out ! 

His amp I am not sure about the B/W... he doesn't say. Not quite sure it can do tens of MHz like I need.. especially with his x1000 amplification ! 

Nope, don't need x1000... as I said x50 will be just perfect for the problem at hand. The lower the amplification, the more B/W I can get out of a given transistor / stage, that's good.

[Neomys Sapiens]

Stupid question for the gang.
If a water electro-valve spec is 24VAC, can I use VDC to control it?
If yes at what voltage DC current?

Yes I am a little embarrassed to ask....

I'm with the Capt.Bullshot here. Basic answer is NO.

Why even try such?
As for someone suggesting that it had been tried with a contactor: I've seen and smelled a control cabinet where someone 'tried' that with around 50 contactors. You could not touch them even at the top plastic around the contacts and it stank like a fire in waiting.

[Zucca]

No, it would not be a "simple" affair to go over to a 3 phase system. Yes, 3 phase does get distributed out to many locations for businesses and for load balancing. For example.....while my road has no businesses close by 3 phase is available. But it's eventually distributed to side streets as shown. One HV line. Single phase. The cost to retrofit all those areas would be prohibitive.

Solar PV panels, batteries, three good inverters (Victron energy quattro) in star configuration.... and wualllla 380VAC three phase where you want, and I am pretty sure the business case is still much better than hanging big ass trafos on wood poles + power lines in the pampa.
I always look up at the flying trafos on wood poles and those things do not inspire confidence.

Coming from Europe, homes and the grid in USA have something in common: if you are good with karate you can damage them pretty badly.

[GreyWoolfe]

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.

Fairly rare, a handful over the summer perhaps. We've had two or three here in my bit of London since the beginning of the year. Depends where you are, when I lived on the south coast they were fairly common, but almost all seemed to happen out to sea.

Here in central Flori-DUH, thunderstorms are almost a daily occurrence.   The weather people can almost take the summer months off (excepting hurricanes) as the forecast is the same just about every day.  HOT, temps in the 90's and heat index over 100.  Chance of rain/thunderstorms 70+%.  In fact, ours came just as we were finishing dinner.  Mrs GreyWoolfe said, "I hear thunder." and kept eating, meaning I had to take the dogs out real quick.  No sooner than getting them back in the house, the skies opened up.  Perfect timing as the Sheppard mix hates getting rained on and doesn't even like getting her paws wet though she tolerates baths fairly well.

No, it would not be a "simple" affair to go over to a 3 phase system. Yes, 3 phase does get distributed out to many locations for businesses and for load balancing. For example.....while my road has no businesses close by 3 phase is available. But it's eventually distributed to side streets as shown. One HV line. Single phase. The cost to retrofit all those areas would be prohibitive.

Solar PV panels, batteries, three good inverters (Victron energy quattro) in star configuration.... and wualllla 380VAC three phase where you want, and I am pretty sure the business case is still much better than hanging big ass trafos on wood poles + power lines in the pampa.
I always look up at the flying trafos on wood poles and those things do not inspire confidence.

Coming from Europe, homes and the grid in USA have something in common: if you are good with karate you can damage them pretty badly.

In the sub-division I live in, all utilities are underground, electrical and cable.  There is a transformer box on the property line with our neighbors to the left.  Last year it failed rather spectacularly and the power company had it replaced and power restored in a few hours.  Quite a process to isolate before replace, it was too far gone to fix-everything inside the box was basically blackened.

[Zucca]

Now this is what I want to install in my home before the end of the year:



The orange box "critical loads" is my home  .

this is the grid cable coming in my home at the main 200A switch:



and this is the same cable arriving at the main dist panel as already mentioned...



I need some advise on how to connect my new inverter(s) between A and B. I am 99% sold to open up the the bottom at the main switch (red arrow in the pictures), brake the phases/neutral connections there and start my new system there.
But I do not know if I have enough spaces to make the bridges/interconnections properly.

Another idea is to do some surgery on the wall and intercept the main grid cable between the main dist panel and main switch and there install my new system....

I heard in USA the mains panel in BUSINESS/COMMERCIAL/INDUSTRIAL system are way better than what they put in home...
Any of the USA gang can point me to where I can buy some nice stuff to modify my mains?

[Zucca]

OK, who fitted the idiot magnet to my car?

Thanks for reminding me to buy a car dash camera...

[Kosmic]

Now this is what I want to install in my home before the end of the year:



The orange box "critical loads" is my home  .

this is the grid cable coming in my home at the main 200A switch:



and this is the same cable arriving at the main dist panel as already mentioned...



I need some advise on how to connect my new inverter(s) between A and B. I am 99% sold to open up the the bottom at the main switch (red arrow in the pictures), brake the phases/neutral connections there and start my new system there.
But I do not know if I have enough spaces to make the bridges/interconnections properly.

Another idea is to do some surgery on the wall and intercept the main grid cable between the main dist panel and main switch and there install my new system....

I heard in USA the mains panel in BUSINESS/COMMERCIAL/INDUSTRIAL system are way better than what they put in home...
Any of the USA gang can point me to where I can buy some nice stuff to modify my mains?

Seem like a lot of troubles. You are sure you are going to save some money doing this ?

Might be just us, but around here electricity is so cheap it would only make sense to install solar panels if you can't get connected to the grid.

[ch_scr]

Now this is what I want to install in my home before the end of the year:



The orange box "critical loads" is my home  .
(...)

Seem like a lot of troubles. You are sure you are going to save some money doing this ?

Might be just us, but around here electricity is so cheap it would only make sense to install solar panels if you can't get connected to the grid.

Remember, it is Zucca your are talking to - he wants absolute reliability and absolute availability on his grid (and anything else he relies on, really). Price is more of a footnote...

[Kosmic]

Now this is what I want to install in my home before the end of the year:



The orange box "critical loads" is my home  .
(...)

Seem like a lot of troubles. You are sure you are going to save some money doing this ?

Might be just us, but around here electricity is so cheap it would only make sense to install solar panels if you can't get connected to the grid.

Remember, it is Zucca your are talking to - he wants absolute reliability and absolute availability on his grid (and anything else he relies on, really). Price is more of a footnote...

I don't know, not sure I would call solar power "absolute availability and reliability". Might have to look into nuclear fusion for that.

[AVGresponding]

Stupid question for the gang.
If a water electro-valve spec is 24VAC, can I use VDC to control it?
If yes at what voltage DC current?

Yes I am a little embarrassed to ask....

I'm with the Capt.Bullshot here. Basic answer is NO.

Why even try such?
As for someone suggesting that it had been tried with a contactor: I've seen and smelled a control cabinet where someone 'tried' that with around 50 contactors. You could not touch them even at the top plastic around the contacts and it stank like a fire in waiting.

Probably because they used 24VDC instead of 12V and it cooked the coil? You might try it if you didn't have easy availability of 24VAC.

Also, what difference does it make to the contacts, whether you use the correct voltage or not? Only thing I can think of is the DC voltage was too low and the contact pressure was therefore low and the switched load was close enough to maximum that it caused excess arcing?

In any case, a control valve wouldn't have that issue. If the valve has a VA rating, just measure the coil DC resistance, that'll tell you the necessary DC voltage if you really want it spot on.

[cyclin_al]

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

You forgot skid-steer machine operators dropping trees onto the road ... major cunts as well. 

This happened as cars and cyclists were passing by, with nothing to make them aware of the life-threatening hazard.

Yep, we had some big thunderstorms and windstorms lately...

[mansaxel]

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

This is similar to the TN-C and TN-S systems⁰ used in Sweden. Once PE and N split, may they never join.  Fools with multimeters measure Ω between PE and N and conclude "They're the same!" because loop resistance is low back to the split point (I usually have below 1Ω since my house is TN-C and the split point is in the main breaker panel) but they're not. Not in a fault condition, which is what PE sits waiting for. 


0: TN-C: 3 phases and PEN
    TN-S: 3 phases, N and PE, split point in utility company.

[tggzzz]

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.

Amaze youngsters by using an analogue scope to quickly and easily measure the RMS value of wideband noise.

[bd139]

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.

Amaze youngsters by using an analogue scope to quickly and easily measure the RMS value of wideband noise.

At amaze them with an HP 3400A which is even easier

Talking of which I need one of them to measure noise figure on something.

[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.

Back when I tried to learn to fly gliders & court SWMBO at the same time (one guess which one missed out!), some of the older club members recalled learning from wedgetailed eagles!

Buzzards over here, or in some areas red kites. But not seagulls; they are deceptive buggers that happily flap their wings when they feel the need.

Many people have been saved from landing out by buzzards. It is a nice complement about your skill when they come to join you in a thermal, rather than vice versa.

Never fly directly underneath a bird; when startled they fold their wings and drop!

[tggzzz]

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.

Amaze youngsters by using an analogue scope to quickly and easily measure the RMS value of wideband noise.

At amaze them with an HP 3400A which is even easier

Talking of which I need one of them to measure noise figure on something.

OK. Go on. Do that by the end of the week, rather than at some indefinite time in the future

[bd139]

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.

Amaze youngsters by using an analogue scope to quickly and easily measure the RMS value of wideband noise.

At amaze them with an HP 3400A which is even easier

Talking of which I need one of them to measure noise figure on something.

OK. Go on. Do that by the end of the week, rather than at some indefinite time in the future

Considering I don’t have any analogue oscilloscopes at the moment I shall defer until some indefinite time in the future

[tggzzz]

You put a Rifa cap back into the unit!?  I hope you got a late date code on that part............... 

I did that with several in my HP8562 spectrum analyser. As with everything in that mechanical marvel, there's no room for anything else.

[tggzzz]

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.

Amaze youngsters by using an analogue scope to quickly and easily measure the RMS value of wideband noise.

At amaze them with an HP 3400A which is even easier

Talking of which I need one of them to measure noise figure on something.

OK. Go on. Do that by the end of the week, rather than at some indefinite time in the future

Considering I don’t have any analogue oscilloscopes at the moment I shall defer until some indefinite time in the future

A clear demonstration of how unwise it is to dispose of anything.