Test Equipment Anonymous (TEA) group therapy thread

[bd139]

Add a TDR to measure cable length, cable impedance (50ohms in your dreams), and connectors quality.

There's no such thing as a good cable at a radio rally. Unless it's an exotic one (triax, GR connectors, an inch across, hardline) or from a reputable outfit. One of the few things I refuse to buy second hand. Although the "Moonraker milspec RG-58" is pretty good - good braid coverage and 0.028dB/m loss. Weighs a ton though.

I can see all the vendors shuttering their stalls as they see you coming down the aisle with that steaming pile of Doc Brown goodness in your hand... 

They might put the prices up which is what worries me 

I worked with a currency trader once. The guy was earning crazy money but was the biggest cheap ass you've ever seen. Drove a 25 year old Ford Escort with more holes than bodywork. His hobby was classic MGs of which none ever ended up in good enough condition to drive on the road. He told me about his escapades going to auto fairs. He said the best way to get a discount on parts was taking his gardening trainers and wrapping duct tape around them a couple of times and wearing an oversized jacket and a too small jumper he got in a charity shop. Paid on average 50% less for the parts than turning up in something respectable apparently 

[mnementh]

Yeah, but by the time you get done making adapters for that $330 RF analyzer to do a half-assed 3/4-assed approximation of what a $90 DE-5000 does out of the box, it'll look like this:



Would it surprise you if they did raise their prices seeing that come down the aisle...?    How much of that $90 will you spend MAKING those adapters? 

mnem
But hey... it's all about where you place your priorities. 

[mnementh]

And that D (tan δ) factor can be directly compared against the datasheet, unlike ESR. Except of course in the case of a 50-year-old cap like this one. 

mnem
The right tool for the job.

[bd139]

Stop selling me things  Next month 

Need to bounce the 475 first

[mnementh]

Fair dinkum, sez I. 

mnem
 

[0culus]

@mnem, which ebay seller did you recommend getting that LCR meter from, again?

[mnementh]

Seller was eina-japan : eBay auction: #283491066156

I waited for an eBay 15% off coupon; IIRC, Labor Day weekend a year ago. Net cost was US$88.40. Be patient though; seller ships economy at that price, took about 3 weeks. I got we-e-e-y frustrated at the time it took once it was stateside; like a week to get to the US, 2 weeks to get from CA to me.  But it arrived full kit (less AC adapter, like I care) and all parts in (Japanese printed) retail packaging at that price. 

mnem
*currently nuking a table saw*

[bitseeker]

This guy is unbeliveable. [...] 

Gotta love using a spectrum analyzer to tune a guitar...

Yeah, that was cool. I never read up on the specs of the HP 3582A and, hence, didn't know it was a 14-bit FFT analyzer. I should try a similar tuning operation with an Analog Discovery.

[bitseeker]

@mnem, which ebay seller did you recommend getting that LCR meter from, again?

Seller was eina-japan : eBay auction: #283491066156

The vendors from Japan are OK. Stick with those for the DE-5000. Don't get lured by the deals from other locations in Asia. They're usually scams.

[Specmaster]

(Attachment Link)

And that D (tan δ) factor can be directly compared against the datasheet, unlike ESR. Except of course in the case of a 50-year-old cap like this one. 

mnem
The right tool for the job.

I do like that DE5000 for its portability but I still much prefer my XJW01, its really accurate and present more data as well at the same time, should you need it and of course its Kelvin based for even greater accuracy for £

[0culus]

Thanks guys. Right now I just need something quick and dirty for finding high ESR caps and the like when I repair a piece of gear, so the DE-5000 is very attractive. Ultimately I would love one of those high end LCR meters like a GenRad Digibridge, but don't want to spend that much right now. 

On the bright side, I've been gathering materials needed to build and experiment with a Jim Williams avalanche pulse generator (from App Note 47's appendices). One problem has been finding 2N2369s in quantity. I got a couple from an ebay seller, but they only had 4 and they were expensive. Wouldn't you know, I found a drawer full of the damn things at my local surplus joint, for MUCH cheaper. Still in factory packaging.

[bd139]

Quick and dirty: https://www.eevblog.com/forum/projects/5-transistor-esr-meter-design/msg2327025/#msg2327025

See start of thread for schematic

Got tonnes of 2n2369’s here. CDIL still produce them and they’re as good as the original parts.

[tggzzz]

Thanks guys. Right now I just need something quick and dirty for finding high ESR caps and the like when I repair a piece of gear, so the DE-5000 is very attractive. Ultimately I would love one of those high end LCR meters like a GenRad Digibridge, but don't want to spend that much right now. 

Take a 50ohm signal generator. Model the capacitor as an ideal capacitor plus a series resistor.  Set the sig gen  to generate a square wave with appropriate frequency amplitude and, for bonus points, DC offset voltage.  Monitor the voltage across the capacitor with a scope.

The waveform you see will be an initial step followed by the usual exponential.

Ignore the exponential and concentrate on the step,. The step amplitude is the potential divider of the ESR, the 50ohms and the step amplitude. Given that the ESR << 50ohms, the calculation is relatively easy.

[mnementh]

(Attachment Link)

And that D (tan δ) factor can be directly compared against the datasheet, unlike ESR. Except of course in the case of a 50-year-old cap like this one. 

mnem
The right tool for the job.

I do like that DE5000 for its portability but I still much prefer my XJW01, its really accurate and present more data as well at the same time, should you need it and of course its Kelvin based for even greater accuracy for £

The DE5000 is 100% Kelvin as well, right up to the clips / tips of the tweezers themselves. Not a damn thing wrong with it, and they're a helluvalot more convenient (and I'll argue, better connection most of the time) than trying to put 4 clips of any sort on 2 contact points on the DUT.

For the price, there's really NO NEED TO CHOOSE... you CAN have both, and I'd argue the DE5000 is a lot more value for the bench space it occupies than yet ANOTHER DMM, which none of us would even think twice about spending that $90  on. 

mnem
 

[mnementh]

Thanks guys. Right now I just need something quick and dirty for finding high ESR caps and the like when I repair a piece of gear, so the DE-5000 is very attractive. Ultimately I would love one of those high end LCR meters like a GenRad Digibridge, but don't want to spend that much right now. 

The DE5000 is a great meter from a daily use perspective. Most of the time, I just use the tweezers; there are very few components I run into they won't get a good connection on. Once you develop your own "fingering technique" for handling them, you'll agree hands down.

mnem
*ducks soggy ol' boot thrown from md's vicinity*

[0culus]

Thanks guys. Right now I just need something quick and dirty for finding high ESR caps and the like when I repair a piece of gear, so the DE-5000 is very attractive. Ultimately I would love one of those high end LCR meters like a GenRad Digibridge, but don't want to spend that much right now. 

The DE5000 is a great meter from a daily use perspective. Most of the time, I just use the tweezers; there are very few components I run into they won't get a good connection on. Once you develop your own "fingering technique" for handling them, you'll agree hands down.

mnem
*ducks soggy ol' boot thrown from md's vicinity*

It does look like it'll do exactly what I need. I'll wait for it to go on sale...in the meantime, following the advice above and using a 'scope and function generator works fine. 

[med6753]

That DE500 looks interesting. I may spring for one too.

Did absolutely nothing TEA related today. Grocery shopping early this morning. Took an old man nap later, which I rarely do, woke up the old Civic and took it for a spin....and that's about it. I thought about working on the 485 some more but that's as far as it got.  Maybe tomorrow. Starting Monday and for the rest of the week I'll be down in NYC visiting and painting.     

[mnementh]

Keep your eyeballs peeled on fleaBay; the coupon I used was one of their seasonal ones, NOT from the vendor. They don't always send out an eMail; sometimes you have to catch it (they usually only last like 24 hours) on the eBay home page. 

mnem
 

[mnementh]

From the Real Virtuality Dept...

   

Sold as "New Other", appear to be "lightly used" & repaired; found a scarred screw like somebody replaced an earpiece. 100% functional! 

First impressions: SDE MUCH improved over DK2 & Rift CE. Barely noticeable, & rotated 45° like the CE, but higher res and better contrast greatly reduce perceived fuzziness compared to the CE. I am actually typing this viewing my browser through the WMR home portal, something I could NEVER stand to do with either of my previous HMDs. Same wearability complaints as other users; lenses too close, need extra-thick forehead pad to get focal distance right & overhead strap to eliminate excess nose pressure. Still better than most FPV goggles. 

I almost bought a few months ago when the full kit was reduced to $299, but I was just overextended due to my recent Ryzen 3700X build. Now they're $380 new/$300-400 used (or more... ) ~$150 is, I feel, a reasonable price for "lightly used" headset only, especially considering I really want to do the Valve Knuckles controllers anyways.

mnem
*Virtual-ily*

[xrunner]

What happens if you take both the RED pill and the BLUE pill together? 

[GregDunn]

What happens if you take both the RED pill and the BLUE pill together? 

"PURPLE!!!"

[mnementh]

I took the RED pill and the BLUEpill; we threw I Ching... out the window. now we are unanimous.

mnem
Also, my socks have NEVER gotten this clean before.

[0culus]

This afternoon I successfully built, on perfboard instead of a breadboard, an example of Alan's latest project:



Really neat little circuit. Instead of feeding the output through a lowpass filter and into an amp, I just used a 7A22 differential amplifier in single ended mode. 

[VK5RC]

A bit of fun, rather than serious TE but amazing bang for buck. The control interface is poor, but it really is tiny - just a bit bigger than a pack of chewing gum.
Rob

[bd139]

This afternoon I successfully built, on perfboard instead of a breadboard, an example of Alan's latest project:



Really neat little circuit. Instead of feeding the output through a lowpass filter and into an amp, I just used a 7A22 differential amplifier in single ended mode. 

Cool stuff. That video is in my YouTube subscriptions queue. I haven’t had a chance to watch it yet. Nice work there though