Recent Posts

1

General Technical Chat / Re: Is LinkedIn worth keeping?

« Last post by coppice on Today at 04:00:26 pm »

I joined some years ago, dumped it when they started to get a reputation for spam and worthless recommendations.

You must have missed something, since they started out as a spam machine on day one. They used to do really sleazy things like harvest email addresses of professional people, and cross send invites to join like sending you "Your buddy Joe Blogs in on LinkedIn, and has invited you to join" while sending Joe Blogs the same invite claiming you were on LinkedIn.

2

Repair / Tektronix deprecated free trial options

« Last post by Circuitauger on Today at 03:58:46 pm »

Hello,

Been needing to get some options onto my Tektronix TDS series oscope for some signal analysis. Found Tek still has the free trial & download of the software package option on their website, installed, everything works fine. The issue however is that unfortunately it seems that Tektronix no longer actually sells license keys and/or option keys for any of their older equipment. 

So currently I’m stuck just leaving the thing on so the number of remaining code launches doesn’t decrement to 0.

Saw on the forums here there’d been discussion on hacking the scopes to unlock options, don’t know if I need to go down that road yet.   

Does anyone know how the remaining trial boot up counter works? Is it writing to some eprom, or can the hdd just be frozen in time from changes, or the trial software just indefinitely uninstalled and reinstalled?

3

General Technical Chat / Re: Is LinkedIn worth keeping?

« Last post by tszaboo on Today at 03:57:30 pm »

I initially thought of it as a Facebook for work related stuff. So you could make use of the contacts you have at work and not have them see the crazy stuff you get up to at the weekend.

I avoid it mostly as it wants to be a job advertising website and is infested with agencies trying to sell me a job that I left years ago.

Some of the headhunters are completely useless. I had one that cold called me on my work phone to try to poach me. I was sitting 1.5m from my boss. Another one sent me a job profile, that "I would be a good match", that I wrote because it was an opening in my engineering department. But there are also good agents and postings on it.

4

Buy/Sell/Wanted / FS: Leader 3282 Stereo RF Sig Gen

« Last post by kloss on Today at 03:56:37 pm »

Leader LG3282 FM Stereo and AM Stereo RF Signal Generator 10 kHz to 280 MHz top of the line model with many great features. Previously used for Car Audio System development work. Included is a copy of the user manual and an Aeroflex carry case, custom designed for similar equipment. Top quality item from Japan. Tested working, calibration recently carried out so spot on frequency. £599.00 Collection or shipping available.

5

Beginners / Re: Bulk input caps and impedance

« Last post by Siwastaja on Today at 03:56:25 pm »

Inductor is possibly worse. Inductor is like a spring, it stores energy then releases it, which means a voltage peak.

In fact, that's a problem with input capacitance to begin with: you are just concerned with the initial current peak, but missing the fact that any stray inductance (from wiring) stores significant energy because of that current peak, and if the current decays "too quickly", then a voltage peak is generated. L of wiring + input capacitance forms an oscillating circuit.

Solution is a lossy element, just like a damper in car suspension: resistance. Do not put the resistor with series with the supply, that way you are generating DC voltage drop and losing power for no reason. Instead, put the resistor in series with the capacitor only.

An electrolytic capacitor is a simple and cheap component which already incorporates enough internal resistance such that it's stable in itself with usual amounts of input wiring inductance.

Only add explicit inductance when
1) you have a real power quality or EMC issue you need to solve and which cannot be solved by capacitance and layout,
2) you know what you are doing and can simulate or prototype/measure; you need to scan wide range of frequencies to prove that you did not create a resonance at some unlucky frequency making the circuit worse than what it was before adding the inductor.

See https://www.analog.com/media/en/technical-documentation/application-notes/an88f.pdf

6

General Technical Chat / Re: Is LinkedIn worth keeping?

« Last post by coppice on Today at 03:56:09 pm »

LinkedIn started out as a spam machine. At one point over half of all the spam being filtered from my in boxes was from LinkedIn, and that was a LOT. I have never been able to take such scumbags seriously as a service provider.

7

General Technical Chat / Re: Why Circuit Breakers DON'T Protect People (electric shocks)

« Last post by mendip_discovery on Today at 03:55:56 pm »

Why does everything HAVE to be a video these days, and then damned lazy posting it to a group.

Anyway, as someone who has taken a few 230V AC shocks and even one rather bracing belt with a few kV. The time you are exposed does make a difference. 10 ms compared to ∞ (or how long before the power is cut) is often the difference between walking away or not.

8

Programming / Re: Linux Dependency Black Hole

« Last post by tatel on Today at 03:55:54 pm »

Hi.

Please don't take too seriously what i'm going to say, because I don't have any hamradio/MCUexpresso experience. To me expresso is a good way to make coffee.

You have hackrf_spiflash and other related command line tools on package "hackrf" officially supported on Debian, and I would bet my last euro they don't use that expresso thing to build that tools. Don't know if there is some firmware available. You'd have to look for it, or look at how firmware is loaded and to write your own firmware accordingly.

Most FOSS software is built with GCC and related tools with the usual letany "configure-make-(become root)-make install". That means there will already be Makefiles to build the hackrf utilities, the firmware loader, etc. You probably could modify and use these Makefiles. That way you can have a good peep at how things are done in the FOSS world when for-profit companies are not involved.

I would look at source packages for hackrf and anything you could be interested in. Probably you'll find quite a good base to start from. If you are not used to GCC way of things, perhaps you'll find easier to use another thing and avoid learning that FOSS way to build.

I can say that having knowledge about the GCC way could very well be worth the hassle. I would say most of linux software is built that way, and you could always get from the repositories a GCC ecosystem to be installed in your system without any dependencies problems whatsoever. Look for the Debian guides; if you start from debian source packages, you could easily even find that most of the work to produce debian packages is already done. Not that you need to create any debian packages to use the binaries you just built with GCC.

Best wishes

9

Manufacturing & Assembly / Re: Long thin part rotating during placement.

« Last post by jmelson on Today at 03:50:47 pm »

Does your P&P have a way to reduce rotation speed and acceleration?  If the top of the part (pick-up tape) is small and the part has a lot of angular momentum, then that is the only way to solve it.  I had this once with a really big ceramic capacitor.  But, in that case, I was able to switch to a larger nozzle, and that solved it.  So, obviously, the part was rotating on the nozzle after the vision sensed it.
Jon

10

General Technical Chat / Re: Is LinkedIn worth keeping?

« Last post by mendip_discovery on Today at 03:49:37 pm »

I initially thought of it as a Facebook for work related stuff. So you could make use of the contacts you have at work and not have them see the crazy stuff you get up to at the weekend.

I avoid it mostly as it wants to be a job advertising website and is infested with agencies trying to sell me a job that I left years ago.