Test Equipment Anonymous (TEA) group therapy thread

[bd139]

Nice job  and big relief 

Just calibrated my OCXO box. Literally both the reference signal and the OCXO output are static and entirely in phase. It takes three minutes for the OCXO to drift half a cycle at 10Mhz. Not bad for £10 shit from china.

It’s plugged into the 5334B now with the OCXO on the ext reference port and the GPSDO on channel A and 10 second gate time and it has been wedged at 9,999,999.99 Hz for over ten minutes.

Pleased with this 

[xrunner]

That's pretty good, and we have the same tastes in frequency counters too. 

[bd139]

Good good. They are very nice counters. Really like mine.

[kj7e]

Nice job  and big relief 

Just calibrated my OCXO box. Literally both the reference signal and the OCXO output are static and entirely in phase. It takes three minutes for the OCXO to drift half a cycle at 10Mhz. Not bad for £10 shit from china.

It’s plugged into the 5334B now with the OCXO on the ext reference port and the GPSDO on channel A and 10 second gate time and it has been wedged at 9,999,999.99 Hz for over ten minutes.

Pleased with this 

That just means you don't have enough digits.

[bd139]

Yet 

Realistically it's perfect for my needs. The main thing is confidence in a source of truth. Secondly it's silent!

Next 5334B 1.3GHz upgrade. diodes and prescaler finally dispatched today after nearly a week  ... crappy seller rating incoming!

[bd139]

Some tants just have a longer leg on the positive, which is a bastard if leg has clipped short for some reason as you then have a 50/50 chance of getting it right  Why cant they all use a common standard of marking that is good across all kinds of polarised caps, oh of stupid old me, that too fecking logical that's why 

Yeah totally agree. This one really gets me annoyed. I notice that X7R SMD ceramic caps are dirt cheap now the supply chains have cleared some of the backlog so I've started replacing tants with them instead. Cheaper, not polarised and even lower ESR.

[med6753]

The 7904 is back together with no further issues.  Currently sitting and cooking. All looks excellent so far. Here's how I dressed the HV lead from the replacement CRT. The intention is to keep it away from everything as much as possible.



And here is how a 7904 CRT compares with a 465 CRT. Quite a bit larger. Probably to accommodate the readout. Going to cut off the anode lead and put it on display next to the 465. I'm getting quite a collection of CRT's. Got that 3 inch one from the OL-1 too. Going to make a display for that one.   

[bd139]

Excellent work as always. Hopefully it won't explode again!

[mnementh]

Some tants just have a longer leg on the positive, which is a bastard if leg has clipped short for some reason as you then have a 50/50 chance of getting it right  Why cant they all use a common standard of marking that is good across all kinds of polarised caps, oh of stupid old me, that too fecking logical that's why 

Yeah totally agree. This one really gets me annoyed. I notice that X7R SMD ceramic caps are dirt cheap now the supply chains have cleared some of the backlog so I've started replacing tants with them instead. Cheaper, not polarised and even lower ESR.

Yeah, in some cases too low. That ultra-low ESR has been credited as the source of oscillation noise in some of the regulator circuits in the frontend of the Rigol 10xx series; it has been suggested that they just replaced tants in the regulator reference circuits with MMLCCs. I assume other series are similarly affected. And of course, you always need to be mindful of the much steeper voltage derating slope of MMLCCs compared to any other type of cap; your circuit may only see 1/4 1/10 of rated capacitance as a result.

Point being to always use a lot of caution and do exhaustive testing when substituting ceramics for other types of cap. 

mnem
*all over the tiny capacitor thang with my tiny whirry flying thangs*

[mnementh]

Excellent work as always. Hopefully it won't explode again!

Ditto! 

mnem
NO tzzzzzt! for YOU!!!

[bd139]

Some tants just have a longer leg on the positive, which is a bastard if leg has clipped short for some reason as you then have a 50/50 chance of getting it right  Why cant they all use a common standard of marking that is good across all kinds of polarised caps, oh of stupid old me, that too fecking logical that's why 

Yeah totally agree. This one really gets me annoyed. I notice that X7R SMD ceramic caps are dirt cheap now the supply chains have cleared some of the backlog so I've started replacing tants with them instead. Cheaper, not polarised and even lower ESR.

Yeah, in some cases too low. That ultra-low ESR has been credited as the source of oscillation noise in some of the regulator circuits in the frontend of the Rigol 10xx series; it has been suggested that they just replaced tants in the regulator reference circuits with MMLCCs. I assume other series are similarly affected. And of course, you always need to be mindful of the much steeper voltage derating slope of MMLCCs compared to any other type of cap; your circuit may only see 1/4 of rated capacitance as a result.

Point being to always use a lot of caution and do exhaustive testing when substituting ceramics for other types of cap. 

mnem
*all over the tiny capacitor thang with my tiny whirry flying thangs*

All good advice. I should have been clear that I've only actually put them in things I've designed from scratch, not as willy nilly replacements for existing tantalum capacitors and suitable derating is applied. I will usually go to somewhat extreme lengths to make sure the same type of capacitor goes in circuit when I do a replacement.

Also to note the MLCC ceramics explode just like tants do if you do push them a bit far or mishandle them during soldering.

[mnementh]

...Point being to always use a lot of caution and do exhaustive testing when substituting ceramics for other types of cap. 

mnem
*all over the tiny capacitor thang with my tiny whirry flying thangs*

All good advice. I should have been clear that I've only actually put them in things I've designed from scratch, not as willy nilly replacements for existing tantalum capacitors and suitable derating is applied. I will usually go to somewhat extreme lengths to make sure the same type of capacitor goes in circuit when I do a replacement.

Also to note the MLCC ceramics explode just like tants do if you do push them a bit far or mishandle them during soldering.

I figured you knew better; just wanted to make sure those playing along at home got adequate warning as well.  I learned these lessons the hard way as our little whirry flying things evolved from a hobbyist toy to legitimate racing hardware with its own subculture. 

Especially the latter! Microfractures from hand-soldering can cause arcing & oscillation inside the capacitor at just a few volts; I've seen it with my own eyes in 5V USB-powered devices!   

mnem
*Lit like Tim Taylor*

[bd139]

Yeah mostly in wun hung lo chargers where they hand solder lead free SMD stuff because it's cheaper than hiring one guy and a pick and place when you're paying people in ramen.

I use the leaded MLCCs, particularly the Murata and Suntan ones thus side-stepping that particular issue 

[nfmax]

Got my PCB for my alarm replacement / SLA charger through and found 18 errors on it on my part 

I suck

Revision 2 in progress...

Hopefully with battery over-discharge protection this time

[bd139]

Yes indeed. Thanks for that tip before 

[FransW]

There is a little something about “time-nuttery”:
The shortest imaginable time step is around 10E(-44) second as we know it.

 It is the time light needs to travel the Planck distance.
Historically the improvement on measuring time has improved one decade every ten (10) years. Currently NIST/BIPM are around 10E(-16) so, following the improvement rate per 10 years it will take roughly another 300 years to close this gap.

Or there is something about physics we do not yet quite understand and that seems very probable.

So, synchronizing my equipment with a fixed and well maintained time reference is all I can do and will have to be satisfied with, ignoring phase noise, jitter and whatever else one can  worry about.
Unless of course, you thoroughly enjoy this state of mind.

To date this time step has not been named, in engineering units the counting stops with yocto”, which covers 10E(-24). The system does not yet go any further down.
My intention is to keep it practical since, in all honesty, I will not be the one to close the physics gap.

[Mr. Scram]

Weird stuff. I'm talking to someone about a device and he voluntarily sent more pictures. These show a different serial number which is obviously a red flag, but it's the next number up from the previous pictures. None of the pictures seem to be known on the internet. I'm not sure what to make of that.

[tggzzz]

Some tants just have a longer leg on the positive, which is a bastard if leg has clipped short for some reason as you then have a 50/50 chance of getting it right  Why cant they all use a common standard of marking that is good across all kinds of polarised caps, oh of stupid old me, that too fecking logical that's why 

Yeah totally agree. This one really gets me annoyed. I notice that X7R SMD ceramic caps are dirt cheap now the supply chains have cleared some of the backlog so I've started replacing tants with them instead. Cheaper, not polarised and even lower ESR.

Note that the capacitance is a function of the DC voltage; in many cases at the rated voltage the capacitance has fallen by 805-90% - so derate more than a little.

In some cases, lower ESR can result in instability; it is a case of RTFM for the surrounding circuit.

[bd139]

Indeed. I'm using 100V MLCCs in 3-8V circuits and 630/1KV ones for 100V p-p RF.

[Mr. Scram]

6666 posts and a 999 thanks to boot. It's a demonic sandwich, even when viewed from Australia!



Okay, 1000 thanks now. Thanks a lot!

Backup because some rights shenanigans seem to be going on.

[mnementh]

Some tants just have a longer leg on the positive, which is a bastard if leg has clipped short for some reason as you then have a 50/50 chance of getting it right  Why cant they all use a common standard of marking that is good across all kinds of polarised caps, oh of stupid old me, that too fecking logical that's why 

Yeah totally agree. This one really gets me annoyed. I notice that X7R SMD ceramic caps are dirt cheap now the supply chains have cleared some of the backlog so I've started replacing tants with them instead. Cheaper, not polarised and even lower ESR.

Note that the capacitance is a function of the DC voltage; in many cases at the rated voltage the capacitance has fallen by 80%-90% - so derate more than a little.

In some cases, lower ESR can result in instability; it is a case of RTFM for the surrounding circuit.

Didn't I just say that? *Goes back to revise his post with even more pessimistic figures* And that? 

mnem
*raw & unfiltered*

[mnementh]

[RANDOM MODE]



[/RANDOM MODE]

mnem
"Oh, I'm goin' straight to Hell... just like my momma said; I'm goin' straight to Hell..."

[mnementh]

Speaking of Whirry Little Flying Things...



I'm currently dismantling my first FPV/Aerial Photography rig; getting rid of the chassis as I know I'll never rebuilt that prehistoric thing and it takes up more space than the last 5 I've built put together.

This one little piece... the PDB... weighs twice as much as the last FPV/AP quad I built, and that's all-up flying weight. 

mnem
flip!!!

[nixiefreqq]

something has been bothering me about my C channel upgrade to the hp 5334b.

looked again at my pictures and something appears to be missing.

seems i forgot to put  half the diodes in the peak detector circuit. (but it works anyway)

puzzled over it for quite a while and then decided it was time for drastic measures.

RTFM!!!

[med6753]

Yep, RTFM is always a revelation.