Recent Posts

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RF, Microwave, HAM Radio / Re: Small multi-pin shielded connector
« Last post by T3sl4co1l on Today at 11:07:19 AM »
Just use ribbon cable and throw some copper tape over it?

Tim
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General Chat / Re: How do organize your Aliexpress orders?
« Last post by sleemanj on Today at 11:07:15 AM »
Also, I don't delete orders, but I do have a tampermonkey script which fades-out completed orders, and highlights orders that are getting near to timing out.

This also helps because the "Awaiting Delivery" tab is not necessarily reliable.

https://imgur.com/gallery/mLBM4

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Well to achieve a negative voltage over a component, one can float it's ground of course, which is what I did exactly. Both ground pins are lifted using a resistor voltage divider to +4V and generously decoupled using three 100nF caps. Yes, this adds inductance to the ground connections, but that should be of not much issue, we are not talking here about GHz range or high attenuation either.

I only find the datasheet of the attenuator a bit incomplete in that regard of not providing the current needed to operate the device (or I could not find it  ???) or if that device needs any other special treatments in circuit. I even couldn't find any evaluation or reference application schematic for this part on the manufacturer's website. So I kind of guessed a bit here and there, hopefully not too wrong.

If I haven't mentioned - both PCBs for the DDS and the ALC are currently being manufactured. The DDS is at a local PCB house, the ALC was sent to ALLPCB, because the local PCB house does not offer low quantity manufacturing on 0.8mm substrate. (Yes a thinner PCB, used a microstrip for the RF path this time).

So let's see which one will be delivered first. ALLPCB shoud be fast, right? So have they told me ;)
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Test Equipment / Re: POWER DESIGNS PRECISION POWER SUPPLIES
« Last post by bitseeker on Today at 11:05:56 AM »
Nice find. Thanks, Barbouri.
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I discovered my problem... my PC has subtle memory issues... this became evident when I started MD5 check summing the downloaded .iso files and getting different answers every now and again for the SAME file.  I know it's hard to believe but a memory diagnostic confirmed I had issues (and the crashed before explaining what the issues were).  My PC is ASUS Z170-K with CMK16GX4M2A2400C14 memory... seems like I am not the only one to have this issue...

... will have to try a different PC.

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General Chat / Re: How do organize your Aliexpress orders?
« Last post by sleemanj on Today at 11:04:05 AM »
All my packages from Aliexpress have either the order code or the "tracking" code (which isn't usually a tracking code, but anyway), or both, printed on them and this can be matched to the order details when it's not clear which order it was.

Even for not tracked packages there is some serial number which the seller typically puts int he tracking number field, and this is printed somewhere on the package.

On the your orders page you can click the "More Filters" drop down and search by tracking number.

Here's a couple of examples from yesterday's packages.









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Projects, Designs, and Technical Stuff / Cheap Relays
« Last post by RukyCon on Today at 11:03:00 AM »
Hello, i want to know your opinion on relays you can get from sites like ebay, banggood, etc. The reason i want to know is because i've been hearing some people calling them good or decent or something like that.
Now i know they won't be as good as the name brand manufacturers but that does not mean they can't be used at all, right?
Thanks.
Note: I don't buy all of my electronic components from ebay or banggood, i do sometimes buy electronic components from mouser or digikey.
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Metrology / Re: T.C. measurements on precision resistors
« Last post by Edwin G. Pettis on Today at 11:02:06 AM »
I quote: "two broken resistors in a set of five for the LTZ circuit is a rejection rate of 40%,"  that is exactly what you said, that is absurd.  That is an inaccurate statement of failure rates and no one would accept such a statement, care to try that one on General Resistance and guess their response, come on.

As to failure analysis, you have to have the items in hand in order to do a proper analysis so you can't claim I didn't make an analysis, I gave you some examples of possible causes for the failure, which one it might be remains to be resolved, since the cost of returning said resistors to me for analysis exceeds the cost of the resistors, it is ridiculous to make a point of it.  You also first said the resistors were reading high, then later changed it to open, obviously they appear to be open, the cause remains a mystery and since you're not qualified to do the analysis, you must accept the fact that the cause remains unknown.  I accept the fact that they failed for some unknown reason, there is nothing left to complain about, we both agree they are broken, the cause at this point is not really relevant.

I don't have a problem with criticism when it is accurate, your are missing the point, I know all about weld failures and how they can occur, they happen now and then for a lot of different reasons, the point is to strive for no weld failures.  In fact, I demand you produce any evidence of my denying that the resistors failed or any thing else that was inaccurate.

While I agree with you about our dimwitted pres, I object to your silly comparison, it has no place in this discussion.  I think all that needed to be said has been said, two resistors have failed, reason unknown, end of story.
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General Chat / Re: Bloody Windows!!!
« Last post by IanB on Today at 10:58:53 AM »
Microsoft have already ceased development on Windows 7 and 8.1

If only...except they haven't. They keep issuing security patches, which means they are still finding bugs to fix, which means after all these years Windows 7 is not finished. This is really something I find disappointing, that Microsoft put so much effort into developing Windows 10 before they had finished making Windows 7 complete and secure. Yes, I know I am being tongue-in-cheek here, if not sarcastic, but really. Why switch from something that must by now (surely?) have most of the security holes patched up to something new with a whole lot of new code and new bugs that will need patching?
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Test Equipment / Re: Handheld meter electrical robustness testing.
« Last post by joeqsmith on Today at 10:58:27 AM »
Swag in this context meaning a stab in the dark or wild guess.   The Gossen is bling. 

Are you asking how I determine which set of contacts to use?  The first thing I want  is to be able to read it when the switch is at one side or the other.   Some rotate 360 so then it does not matter so much.   I try to look for contacts that I can tack into without disturbing anything or adding heat to the switch.  I also like to find contacts with a lot of surface area.  Basically, I don't want a short pad in case the wiper cuts all the way through it.   In the end, when that has happened, everything had major damage so I doubt it really matters too much.   

We also have the visual data to go along with it. 
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