Test Equipment Anonymous (TEA) group therapy thread

[25 CPS]

If you all are wondering where have I been over the last few days, I have been to the local steam train gala on the Epping Ongar railway, something that I have had on my bucket list for sometime to do, and is now ticked off. For those that don't know, this is a 6.5 mile long track that was once part of the London Underground network. It was shut down and acquired by enthusiasts who started their own little service but also ran into trouble and the track lay idle for a while and 10 years ago a new group was formed and converted it over to diesel and steam powered locos, and this weekend saw its 10th anniversary with a couple of visiting locomotives.

I took lots of video, and now I'm grappling with trying to learn how to effectively edit the footage to remove all of my shaky camera work etc for my YT channel, using Da Vinci Resolve, which is a steep learning curve, but so much better than the basic tool that YT give you.

I might be misremembering but I believe London Underground's measurement chaining still starts at Ongar since it was the easternmost part of the network.

[VK5RC]

Been 'doin' some real Ham radio, not showering, skulking in the 'shack' but actually using some of my favourite TE - my HP / Ag 8561E and its tracking generator.

I am in the slow process of building an HF tranceiver - so have just wound and tested/adjusted a set of band pass filters. Used Hans Summers' (QRP Labs) kits - so much easier (and cheaper) than trying to source the bits individually. Quite a bit of futzing with the lower bands - most needed turns removal to get a good filter profile.

Next step is an audio amp with some of SOTA-Beams DSP for noise reduction. Haven't fully ruled out about a semi-software defined radio but in general I 'hate' computers (so bloody slow to switch on, s-w updates, anti-virus etc etc) so much prefer a 'hardware defined radio'

[tautech]

Been 'doin' some real Ham radio, not showering, skulking in the 'shack' but actually using some of my favourite TE - my HP / Ag 8561E and its tracking generator.

I am in the slow process of building an HF tranceiver - so have just wound and tested/adjusted a set of band pass filters.

Charlie Morris does some interesting stuff that might interest you:
https://www.youtube.com/c/CharlieMorrisZL2CTM/videos

When I visited him last July he was about to move house but he hasn't posted any content since. 
Must flick him a message.......

[VK5RC]

@tautech - thanks for the heads up, lots of good stuff really on the webs - but 'signal to noise' not always guaranteed, 👍

[tautech]

@tautech - thanks for the heads up, lots of good stuff really on the webs - but 'signal to noise' not always guaranteed, 👍

Charlie has nothing like your experience nevertheless his continual tweaks to his projects make for interesting viewing like the one a year or so back when he got across the Tasman on just 5W.

[mansaxel]

I was limiting the list intentionally at 3-terminal ones. Otherwise I would have not only included the L200, but also the LM104, LM106, LM2991, LR8K4, SG1501, SG1532, ....
LM150/250/350 is a 3A adjustable between the 117 and the 138.

That's an interesting one!
I've attached the datasheet of it. Is there a similar one of the SG1501A from Linear Technology?

An interesting one? I'll give you some more:
<snip>

I could give you some more, but then you would curse me or worse. So, not now..

My addition to the proliferation of regulators would be the Raytheon 4195. 8-pin DIP dual 15V supply, good for 100mA. Were it not discontinued and only showing up in those "we can sell you any NSN, yes, really, promise, just a 3000% markup" sites I'd buy tubes of it. Just what I need for my small analog projects.

[mansaxel]

Anyone wanna take a risk it works?

Won't ship to the dangerous "abroad". 

[Neomys Sapiens]

I was limiting the list intentionally at 3-terminal ones. Otherwise I would have not only included the L200, but also the LM104, LM106, LM2991, LR8K4, SG1501, SG1532, ....
LM150/250/350 is a 3A adjustable between the 117 and the 138.

That's an interesting one!
I've attached the datasheet of it. Is there a similar one of the SG1501A from Linear Technology?

An interesting one? I'll give you some more:
<snip>

I could give you some more, but then you would curse me or worse. So, not now..

My addition to the proliferation of regulators would be the Raytheon 4195. 8-pin DIP dual 15V supply, good for 100mA. Were it not discontinued and only showing up in those "we can sell you any NSN, yes, really, promise, just a 3000% markup" sites I'd buy tubes of it. Just what I need for my small analog projects.

See here, as I already wrote about the RC4194 (the full version):
https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/msg4218085/#msg4218085

[ch_scr]

Actives or passives ?

I'll probably keep an eye out for something like a P6339A or two.

One of these ?
https://www.ebay.com/p/1100242214

Seems expensive but buffered and passive, how does that work ? 

 

LOL, ah sooo, it's really an active probe ! 

Nope, the probe head and cable are standard passive jobbys, but since the scope input is only 50 and not the usual 1 Meg (to be used with passive probes) *. That points to what "magic" is inside the box - an impedance converter (aka an buffer amplifier) that has 1 Meg input and 50 output impedance, but a (hopefully flat) gain of 1. Now how you do that for the given bandwith (and with a constant phase delay as well!), that's where the magic comes in .
* The cable between probe head and scope is "1Meg impedance" as well btw, which explains why one can't extend it with 50 coax that might look the same but isn't, most people try at least once and end up scratching their head why it won't work - I know I did 

[capt bullshot]

Me too likes these for prototyping and tinkering, it's useful to have a small stock of them at hand - either these and similar chinese ones, or more professionally marketed ones from more professional suppliers and manufactureres like Recom, MuRata, ...

[bd139]

If you all are wondering where have I been over the last few days, I have been to the local steam train gala on the Epping Ongar railway, something that I have had on my bucket list for sometime to do, and is now ticked off. For those that don't know, this is a 6.5 mile long track that was once part of the London Underground network. It was shut down and acquired by enthusiasts who started their own little service but also ran into trouble and the track lay idle for a while and 10 years ago a new group was formed and converted it over to diesel and steam powered locos, and this weekend saw its 10th anniversary with a couple of visiting locomotives.

I took lots of video, and now I'm grappling with trying to learn how to effectively edit the footage to remove all of my shaky camera work etc for my YT channel, using Da Vinci Resolve, which is a steep learning curve, but so much better than the basic tool that YT give you.

Looking forward to that. Make sure you post a link in here

[capt bullshot]

Put the board back in the cabinet, reconnect the flat flex going to the front panel, was a bit short. So I was eyeing all around the bench for something suitable to prop the board a bit, which would also make it easier to work on. Look what I found, perfect !!!! 

Then I applied power, tried my USB stick and what do you know, it works now !!! 
As you can see on the close up picture, the blue LED on the USB stick is lit, there is activity !
So I plugged the speakers, and hey presto music there was ! It was reading my MP3 files just fine ! I could switch from one track to the next as well, it was working perfectly.

Thrilled by this success, I immediately added an SD card to the mix to see if that would now work as well. Alas no.... so I then switch back the USB stick..... won't work anymore !!! 

So since it DID work once... it means there is nothing fundamentally broken in this stereo. CPU is fine at the least, which is the main relief. So must be an intermittent contact somewhere. Tried applying pressure with a pencil (plastic sharpie, non conductive    )on the USB connector and surrounding discrete components, the CPU even... no luck, it won't come back to life. 

My guess: Once the SD card failed reading, the (usually lowest level crap) software didn't handle this correctly, got into a state where file system access to any mass storage won't work anymore until a hard reset.
So USB should work again when you turn it off and on.
The real matter with this kind of crap is, you never know it's a software or hardware failure.

[capt bullshot]

Who knew, who should have known.

At least, it looks quite similar to mine. But wasn't able to recognize because of the different case.

Pretty same.
Cursor missing?

No, hidden inside the casing.

[capt bullshot]

To risk or not to risk:

https://www.ebay-kleinanzeigen.de/s-anzeige/tektronix-577-d2-defekt-/2123531071-168-3793

With the exception of the CRT (and special transformer / variac - but hey, are not expected to faill), there shouldn't exist any unobtanium or unreplaceable stuff inside, looks in good optical shape at least. Hard to find a good place for it due to its size, you've seen mine, it's still sitting at the same location.

[BU508A]

I was limiting the list intentionally at 3-terminal ones. Otherwise I would have not only included the L200, but also the LM104, LM106, LM2991, LR8K4, SG1501, SG1532, ....
LM150/250/350 is a 3A adjustable between the 117 and the 138.

That's an interesting one!
I've attached the datasheet of it. Is there a similar one of the SG1501A from Linear Technology?

An interesting one? I'll give you some more:
<snip>

I could give you some more, but then you would curse me or worse. So, not now..

My addition to the proliferation of regulators would be the Raytheon 4195. 8-pin DIP dual 15V supply, good for 100mA. Were it not discontinued and only showing up in those "we can sell you any NSN, yes, really, promise, just a 3000% markup" sites I'd buy tubes of it. Just what I need for my small analog projects.

See here, as I already wrote about the RC4194 (the full version):
https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/msg4218085/#msg4218085

NAWTS

I have ordered 20 RC4194D from here: https://www.utsource.net/itm/p/404529.html
This is one of the cheapest sources I was able to find online.
It seems, that those parts are used ones. Will report back when they arrive.

On a side note: New customers are getting a 10% discount on the ordered parts for their first order.

[tggzzz]

Who knew, who should have known.

At least, it looks quite similar to mine. But wasn't able to recognize because of the different case.

Mine, from school days.

Unfortunately the second one is jammed. Anybody know a good idiot's introduction to repairing them?

[m k]

Cool it in the fridge and then warm the case with hands and tap gently.

[m k]

Other risk.

https://www.ironplanet.com/for-sale/Tools-Tektronix-576-Curve-Tracer-Nevada/6761123?h=5000%2Cq%7CTektronix+576+Curve+Tracer&rr=1&hitprm=&pnLink=yes

[m k]

Is Burr-Brown 2D216 needed?
If so then how much?

[tautech]

Actives or passives ?

I'll probably keep an eye out for something like a P6339A or two.

One of these ?
https://www.ebay.com/p/1100242214

Seems expensive but buffered and passive, how does that work ? 

 

LOL, ah sooo, it's really an active probe ! 

Nope, the probe head and cable are standard passive jobbys, but since the scope input is only 50 and not the usual 1 Meg (to be used with passive probes) *. That points to what "magic" is inside the box - an impedance converter (aka an buffer amplifier) that has 1 Meg input and 50 output impedance, but a (hopefully flat) gain of 1. Now how you do that for the given bandwith (and with a constant phase delay as well!), that's where the magic comes in .
* The cable between probe head and scope is "1Meg impedance" as well btw, which explains why one can't extend it with 50 coax that might look the same but isn't, most people try at least once and end up scratching their head why it won't work - I know I did 

Ahh, the joys of owning a 50 Ohm only input scope ! 

[nixiefreqq]

this is sick and perverted.

and yet........i am tempted to take a walk on the wild side.


https://paxer.net/voyager/

[BU508A]

this is sick and perverted.

and yet........i am tempted to take a walk on the wild side.


https://paxer.net/voyager/

I'm sure, you would do it only for this key:


    

[tggzzz]

Actives or passives ?

I'll probably keep an eye out for something like a P6339A or two.

One of these ?
https://www.ebay.com/p/1100242214

Seems expensive but buffered and passive, how does that work ? 

 

LOL, ah sooo, it's really an active probe ! 

Nope, the probe head and cable are standard passive jobbys, but since the scope input is only 50 and not the usual 1 Meg (to be used with passive probes) *. That points to what "magic" is inside the box - an impedance converter (aka an buffer amplifier) that has 1 Meg input and 50 output impedance, but a (hopefully flat) gain of 1. Now how you do that for the given bandwith (and with a constant phase delay as well!), that's where the magic comes in .
* The cable between probe head and scope is "1Meg impedance" as well btw, which explains why one can't extend it with 50 coax that might look the same but isn't, most people try at least once and end up scratching their head why it won't work - I know I did 

Ahh, the joys of owning a 50 Ohm only input scope ! 

Yup; they are better That's why I like my Tek 485.

Just use a "low" impedance Z0 resistive divider probe. "Low" because its input impedance is >=500ohms, whereas a bog-standard so-called "high" impedance passive probe's input is ~80ohms at 100MHz -- and rings at ~100MHz if you use the 6inch ground lead. Plus you can make them yourself

[tggzzz]

this is sick and perverted.

and yet........i am tempted to take a walk on the wild side.


https://paxer.net/voyager/

There's a decent GPL HP15 emulator, the one I normally use on my desktop...
H E W L E T T · P A C K A R D 15C
A Simulator for Windows, Linux and macOS
COPYRIGHT © 1997-2014, Torsten Manz Home page:  http://hp-15c.homepage.t-online.de

Or for Android...
https://play.google.com/store/apps/details?id=org.efalk.rpncalc

[dl6lr]

To risk or not to risk:

https://www.ebay-kleinanzeigen.de/s-anzeige/tektronix-577-d2-defekt-/2123531071-168-3793

Well I was tempted by the working 577 D1 for 800 bucks. But successfully hesitated to much, so it has gone