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thanks! let's do it again soon. 

Rookie

People here are wearing shorts :P

 

So long for now; look forward to another chat.  Thanks for organizing this, Martin.

Rookie

Thanks everyone for participating. It's snowing here, again.

nice chatting with you. It's at least double digits here in Cleveland, OH so we were thinking of throwing a party =)

 

Rookie

I have to go to a seminar.  Nice chatting with folks here.  BTW, here in Boulder, CO it rained then snowed last night, by 8 am the snow was melting and the high today will be > 50F.

Rookie

@Martin--"There's a whole story about that color"  I think you have a story about everything ever done in electronics...

Rookie

Turned yellow? I thohgh all Fluke meters were yellow. Oh that;'s right, the old ones were a different color. Never mind I was thinking of the yellpw holsters. There's a whole story about that color.

Martin

I've got several handheld meters here. One is 24 years old.


I've got 3 Fluke 8060As of that age. I far prefer them to my Agilent U1251A. Unfortunately they are beginning to show their age. They have turned yellow and the on/off switch is going. I have had to replace (and void the calibration) the fklying battery connector on each one.

Blogger

When I used to work at Keithley I saw quite a few null meters or old electrometers with analog needles on them still being used. Pretty sure the guys using them weren't still keeping the calibration up to date for the last 40 years =)

Rookie

DMM makers used to give us editors their handhelds. I had too many so I gave them away to friends.

eafpres, I've got several handheld meters here. One is 24 years old. Might ne work comparing the construction over the years.

@Martin--"most such DMM measurements are done with a bench meter".  Now I'm thiking about the pushbutton switches on those bench DMMs.

Rookie

In fact, you might even create a "virtual instrument" to simplify the user interface to pass/fail.

Today, most such DMM measurements are done with a bench meter and it might even be automated.

eafpres, many companies use handheld DMMs in production. Often the same meter might be used in more than one setup, say to measure voltage and then current. I supposed there is some exposure, but if you;re using a handheld meter for production, then the uncertainty of the measurements isn't a big concern.

The last time I was doing inside renovation was before mobile phones and digital cameras...

Rookie

eafpres, I have photos of inside every wall in my house. Took pics every day during renovations.

Of course, the old analog Simpson meter had a rotary switch too.

Rookie

@Martin--it is interesting to think through this switch thing.  All handheld DVMs/DMMs have at least one big rotary switch.  When we used those in production, they had to be calibrated/certified.  There were stickers on them showing the dates, and when they were due back to re-cert.  But I don't ever recall anybody checking the meter if they changed the rotary switch.  There is some exposure there that you could be doing bad measurements.

Rookie

@eafpres, it depends on the application. I wouldn;lt do that if you needed to maintain calibratiion. You wouldn't want to ship out-of-spec product or hold back good product. But if you're just experimenting in the lab, well.

Yes, at Rigol we use similar keys for options like Advanced Triggering, Serial Decoding, and Deep Memory options.

Rookie

Last time I reconfigured my home AV stuff I took several pictures in case I couldn't figure out the cabling later.  I didn't want to have to re-figure it all out.

Rookie

Chirs, as we now know, some scope companies offer additional features that are software enabled. They use encrypted keys now because apparently some people had figured out the key codes and were even selling copied keys.

@Martin--so if you had a measurement system and you changed the gain via the DIP switch, did you think it necessary to recalibrate or at least measure something you considered a known?  Switches can fail, you can set them wrong, they can add noise, etc.

Rookie

I used to work on panel meters that use DIP switches to change resolution (think add a digit). If anyone went inside, they could figure it out. All you had ot do was remember the original setting if this didn't work. Today, you take a picture with your phone before changing things.

I agree completely! but not everyone offers BW upgrades at all and if you are cracking into the code or making small changes on the board you'd have to know a lot about the design to be sure you were getting correct cal constants and the like. 

 

Rookie

Many on old analog board used DIP switches for setting amplifier gains.

"There was a time when you could change some equipment with DIP switches either legit from the outside, and sometimes less legit if you got inside and found the DIP that set configuration. I once had a setup to measure velocity of projectiles using two optical sensors spaced a known distance apart. You could change the range of the time and the units it reported in via a DIP switch."

Chris, I would think that if a scope were designed for a particular BW that it would meet those specs. Otherswise your customer would not be happy to find it's not upgradeable.

I don't know that anyone does it this way, but you could envision a manufacturing system where they test the scopes on the line and, in essence, bin them for BW. So the best performing units get the high BW model numbers and so on. So, I don't think its completely unrealistic to think that their could be some issues with hacking in a BW upgrade.

Rookie

"If they don't work, can you backpedal?" There may be a way to return the instrument to its factory settings.

There was a time when you could change some equipment with DIP switches either legit from the outside, and sometimes less legit if you got inside and found the DIP that set configuration.  I once had a setup to measure velocity of projectiles using two optical sensors spaced a known distance apart.  You could change the range of the time and the units it reported in via a DIP switch.

Rookie

antedeluvian - I guess that depends on how you did the upgrade. If you got your soldering iron out to do it, then you may or may not be able to put it back. Often this would be users who don't care all that much about the cal doing this sort of thing. If I didn't care about the precise cal or warranty I'd just measure a few test points and remember if it is a little high or a little low at high frequency and go from there.

Rookie

If the instrument were calibrated for its full BW at the factory, then in theory it's in cal when the higher BW is enabled. Most isntruments have a digital filter that cuts off the BW at some point untin unlocked.

Chris

If I were going to upgrade the BW on the sly I'd definitely run whatever auto-cal sequence I could as well as a few tests.

If they don;t work, can you backpedal?

Blogger

I guess you could call this a hardware hack.
When I was just out of college, there were over-the-air subscription TV channels. Every electronics company in the boston area has a schematic for a channel 68 decoder. the were based on either and LM1800 or LM1310 stereo decoder. I even made a PCB as I had worked in a PCB factory in HS and college.

I'd assume, if done legitimately, that the instrument contains cal points across all the bandwidths it could be used and doesn't need redone. On our Rigol scopes we don't offer a legitimate after sale BW upgrade. On units like that you may be taking your chances a bit more. If I were going to upgrade the BW on the sly I'd definitely run whatever auto-cal sequence I could as well as a few tests.

 

Rookie

well, it certainly voids the warranty.

Blogger

antedeluvian--we had similar needs for using HP/Agilent network analyzers on production lines.  the HP boxes were easy to control over IEE 488 (GPIB) using an interface card in a standard PC.  Then we controlled when to make a measurement by the PC, with a GUI.  The data all came over to the PC and were analyzed for pass/fail criteria against stored return loss profiles for reference devices.  So in effect the instrument becomes virtual like Martin says, and it is up to the test engineers to make sure their code is right.

Rookie

That is, do you ahve to recalibrate to be assured taht the new BW is in spec?

Chris, does unlocking a feature (say increased bandwidth) void a calibration, even if done legitimately?

Many instrument hardware platforms today, such as scopes, support an entire series of models based on available firmware options. Those interested may be able to change their instrument's capabilities through firmware. that is where the risk of proper calibration and warranty can come into play.

Rookie

Also Visual Basic, if anyone uses that anymore.

antedeluvian, some people would call that a virtual instrument. LabVIEW, VEE, ATEasy, Matlab all do that very well.

http://edn.com/design/test-and-measurement/4312996/Anechoic-chambers-rise-from-the-pits

RF/EMI chamber installation are often custom. I wrote about that several years ago.

I once did some work with Stanford Research Systems Model DS345 Synthesized Function Generator. I didn't like their user interface, but the provided the details on controlling the device via an RS232 port. I set up a UI (at least a portion of the UI) in Excel.

Blogger

As far as modifying equipment and providing to others, probably not if it was off the shelf equipment, and especially if it had one of those stickers that says warranty voided if sticker is torn, missing, etc.

Rookie

When I was in the antenna business, the largest "piece" of test equipment was the RF test chamber.  It had a source horn and a network analyzer.  Everything else was custom, and was modified frequently.  There has been an issue for a long time in the antenna business that the gain and pattern tests are not standard, and often published specs / test results are not believeable.  We went through a test of 5 or 6 global sites, sending around a set of carefully designed and fabricated test antennas.  We found 1 dB from the lowest reported gains to the highest.  1 dB is a large error for most antennas.

Rookie

antedeluvian, you've designed signal-conditioning circuits, but ahve you ever done inside your test equipment?

eafpres, I suppose some test engineers have "upgraded" their equipment, but would you mess with equipment you didn't own?

When I worked at Extech (multimeters) people would send back their meters because they fried. Why? the user repalced the fuse with a wire.

 

I was thinking of test engineers "upgrading" their own instruments for some reason.

Rookie

eafpres: Hey if you can figure it out more power to you. It's also a matter of if it's for your own use or do you share or even sell your code.

you pick up a used scope, or you have an old outdated one, so you find the risk acceptable. I can't imagine someone investing in new equpment and licensing and then taking the risk.

Blogger

I think the modification and hacking to test equipment happens on the 2nd tier

Blogger

A lot of test equpment has embedded software as well as software you can load to do certain things.  What if someone writes their own code or modifes the original code?  Is that a hack or a modification?

 

Rookie

Many an engineer has designed some kind of signal-conditioning circuit to go in fromt of test equipment, though.

I've been to many engineering labs over the years and I can't recall anyone "hacking" test equipment. That's because of warranty and calibration issues.

My unlocked iPhones (3 in my house) tell me it's almost 1:00 here in the still frozen northeast. Today, we're discussing modifying test equipment, yes or no? I make a distinction between modfying and hacking. electrical engineers modify, code  warriors hack. Do you agree?

 

then again, if you look at best buy, they have everything radio shack does, minus the few individual components, so who knows.

Blogger

I think their biggest problem is that they don't have a clear "core". Are they parts? components? Accessories?

Blogger

Greeting Blaine. It's been a while.

 

Hi everyone.  Blaine Bateman

 

Rookie

radio shack has been scrambling to fix themselves for some time. They had a big call for ideas back in 2011 with the goal of getting the diy crowd back.

Blogger

Has everyne seen yesterday's story about Radio Shack?

hello everyone. Just getting in here a little early in preperation!

 

Blogger

@Zeeglen: A time bomb gotcha? Care to elaborate on that?

Blogger

Hi Martin. Hi everyone.

Blogger

I have the small bench top Rigol DSA815 spectrum analyzer that I'd love to be able to run off 12V DC. I know I can strap a gell-cell and 12V to 120 VAC inverter on the back, but it would be so much more elegant to insatll a DC power jack on the back and figure out how to tap into the internal power supply.

Blogger

I might do a hardware improvement, but too many things can go wrong when monkeying with the software.  Plus I can see OEMs planting "time bomb gotchas" that get triggered by unauthorized code updates.

Blogger

When is modifying or "hacking" test equipment worth the risk?



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