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1
Repair / Re: Repair of Solartron 7081 SN#718
« Last post by pigrew on Today at 01:34:50 am »
The next step of my repair is to replace the input connectors, so that I can measure external signals.

I received the LEMO-style sockets, and have replaced the rear connector. I used a dremel-tool to cut an extra flat in the socket, so that the red mark is in the "up" position.

I still have the covers off the unit, so I won't post any exact numbers/noise results. Measured resistances are fairly accurate. Using an old crappy 1.3m long coaxcable, I measured about 300 MOhm input resistance in kohm mode. In true resistance mode, it was hitting the limits.

Unfortunately, the measured voltages seemed way off, reading about 9.996 V with a 10 V input (~400 ppm). This could be due to dirty PCBs (I need to give them a bath, first desoldering the front/rear input switch, I think everything else is water-safe). Another possibility is aged/damaged components, which means I may need to just recalibrate it. I saw one person reporting a leaky integration capacitor, it may be worth investigating that, too. I think this would mean that the measured voltage would be a function of the integration period selected? Or is there a better way to test the capacitor?

Oh... one other thing... My meter came with a front-panel of a binding-post breakout box. I may try to re-use it. I wish it had come with the box itself... Cry.
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Microcontrollers & FPGAs / Re: PIC32 evolution
« Last post by Karel on Today at 01:33:26 am »
You can easily patch the GCC compiler without doing anything illegal (because we only alter a GPL licensed binary):

- save the hash: sha256sum /opt/microchip/xc32/v1.42/bin/xclm

- backup /opt/microchip/xc32/v1.42/bin/xclm

- compile a new "xclm" binary using the following C code:

Code: [Select]
int main(void)
{
  return 6;
}

and copy it to /opt/microchip/xc32/v1.42/bin/

- save also the hash of the new binary: sha256sum /opt/microchip/xc32/v1.42/bin/xclm

- backup /opt/microchip/xc32/v1.42/bin/bin/gcc/pic32mx/4.8.3/cc1

- open /opt/microchip/xc32/v1.42/bin/bin/gcc/pic32mx/4.8.3/cc1 with a hexeditor and
  replace the three occurrences of the old hash with the new hash.

That's it.  Works fine here with all optimization settings.

This method stopped working with XC32 v2.10.

The solution is to simply change the return value in the C code from 6 to 2.

3
Doesn't have to be SINGLE capture.
On that image he has TWO consecutive trigger events overlapped on the screen.
Unless he has infinite persistence on, there is no way you should have those two waveforms simultaneously on screen.
Every new trigger even erases previous capture buffer.
So yes I apologize for oversight, if you set infinite persistence than you can get that screen.
In all other cases, all previous waveforms cannot stay on screen. Only the last one. And decode for that one.

If it were chinese scope all would be enraged how "chinese shit" is no good. When big guys do it, it's not a bug, or not their fault...

Of course it is a bug.
4
Dodgy Technology / Re: 3DFS's VectorQ Digital Electricity Technology ?
« Last post by Cerebus on Today at 01:31:01 am »
3DFS Technology maintains power factor at unity, harmonics below 2% and automatically balances phases in power networks at all times no matter the load profile or energy consumption patterns.

Prove it!

And I don't mean another of your buzzword loaded paragraphs filled with insults at your interlocutors. I mean, either some solid, cogent, complete technical explanation of how your systems achieve your claims (i.e no more of this 'We do it by delivering microamps per microsecond in real time' tosh but a properly argued white paper or similar, you must have one somewhere) OR details of one or more reference customers who are prepared to publicly stand up and say it works.

If you cannot, or will not, offer one of those two then the only reasonable conclusion is that you're either deluded, or deliberately pedalling rubbish and we can safely ignore you, your extraordinary claims, and tell anyone who asks that they ought to avoid your products like the plague on the grounds that you can't or won't properly explain or defend them.
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General Chat / Brian Krzanich (Intel) has Left the Building
« Last post by kfnight on Today at 01:30:40 am »
http://money.cnn.com/2018/06/21/technology/intel-ceo-out/index.html
 
I never was a fan of the guy or where he was leading Intel. Here's to hoping that the next CEO does a better job.
6
bumped until i'm home.. as always... thumbs up.

I hope you enjoy it when you get home!
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Test Equipment / Black Star Nova 200 Frequency Counter
« Last post by 2E0KKQ on Today at 01:29:58 am »
Hello, I've recently purchased a Nova 200 frequency counter and curious if anyone is familiar with its first power on state.

When I turn it on all the LCD zeros flash up then go off until the first gate loop starts. I wondering if this is normal?

I have replaced all the electrolytic caps and 3 tantalums thinking they could be the issue.

When I first received the counter it wasn't doing this, then after a day or two it started ,so naturally thought the caps could be at fault.

All the capacitors replaced and any possible dry solder joints have been reworked.

Any ideas or even if this is common on other counters. I just hope an IC isn't about to fail!

Will
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Beginners / Re: Problem with first lab power supply
« Last post by rstofer on Today at 01:29:25 am »
The op amp power supply is also unregulated and I don't see the source for +5V used for the pot and the LED.
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Beginners / Re: Oscilloscope training class (long)
« Last post by w2aew on Today at 01:28:16 am »
Here's another take at this talk.  This recording was done at a local ham radio club meeting.  It is slightly updated from the original video that started this thread in that it also includes basic information about digital scopes as well.  The presentation is entitled "Basics of Oscilloscope and their Use in the Hamshack".  However, this video is only "Part 1", covering the basics of oscilloscopes. 

The club used several cameras during the recording, so I think the final product came out quite well.  Video is a little over an hour long:

10
I'm opening this new thread since it does not strictly belongs to existing two threads: one about what is called EEZ H24005 programmable power supply and another discussing DIB ("DIY instrumentation bus").

This one is about making EEZ H24005 a) even more modular and b) more “completed” design/project that does not include ready-made modules. That also does not imply that EEZ H24005 project is dead, and that people who built it or get it via crowdfunding campaign cannot count on further support.

Currently EEZ H24005 is modular in the sense that so-called Power modules are independent from digital control (Arduino Shield). Theoretically one can make another Power module with different capability and functionality as long as its dimension are within 165 x 74 mm and can use 26-pin connector for both power and control lines.
One possibility is to redesign that module in line with proposed DIB where PCB could be 145 mm tall and 170 mm wide (or even wider). That gives enough additional space to host a complete AC/DC power converter, what will be presented in future posts.

More “completed” design mean replacing of used ready-made modules with own design. In case of the EEZ H24005 that means giving up from Arduino Due, AC/DC module (from Mean Well) used to deliver 48 V for Power Board and AC/DC module (from Vigortronix) for delivering 5/12 V for powering Arduino Shield and 12 V cooling fan.

Mentioned changes are not trivial at all (i.e. cannot be done in few days): replacing Arduino Due means migrating firmware to the new platform and replacing AC/DC parts include playing with mains voltage that require different discipline during development and testing to stay alive and also provide something that is robust enough to be safe and secure during operation under all (or at least imaginable but practically possible) conditions.
Just that two reasons are enough to keep topic separated from existing EEZ H24005 project since even if I succeed with it that don't necessarily that many people will be interested to cope with different MCU and especially with circuit that works with mains voltage.
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