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Test Equipment / Re: Recommendation on a decent LCR meter?
« Last post by CJay on Today at 04:59:32 am »
I picked up an Agilent U1731B recently on eBay from n2cbu, none left right now but it'd be worth keeping an eye on their sales as it was an absolute bargain at about $50 plus shipping
$50 = You SUCK! :-+

The replacement, U1731C, goes for $330 (seems MSRP & street are the same in this case  ::)).
It was too good to miss, I've used it in anger precisely once but it's in almost factory condition, the only problem is that it's missing the tilt stand on the back and although Agilent sell them for a reasonable price they want a ridiculous amount of money to meet minimum order fees, shipping etc. so I am keeping an eye out for someone who can tag one onto a larger Agilent order.

Looks like more came into stock $59 USD this time.....  https://www.ebay.com/itm/Agilent-U1731B-Handheld-LCR-Meter-Used-very-clean-tested-in-spec/142873856882?hash=item2143f20b72:g:srUAAOSwH3RbT-JU

Well I can vouch for the fact that mines is in almost factory new condition, I'm extremely happy with it and it made it across the Atlantic far faster than I expected.
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schematic?
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Exhibit: http://ds.yuden.co.jp/TYCOMPAS/ut/detail.do?productNo=UMK316B7225KD-T&fileName=UMK316B7225KD-T_SS&mode=specSheetDownload

It's being sold as a 50V, 2.2uF part, but it's -30% at only 6V!

On a complementary note, today I spec'd a "2.2kohm 300mA" ferrite bead, that is -30% at 150mA.  Not bad, most ferrite beads are as weak as, well, the above capacitor!

Tim
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Microcontrollers & FPGAs / Re: [C] Pointers - what is the point?
« Last post by sokoloff on Today at 04:56:10 am »
Agreed on the last. There is nothing implementation dependent or language undefined in my sample above. (At least none that I'm aware of, of course.)
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Using a standard makes sense when there is a standard which provides the needed functionality for that particular application in an effective manner.

Since applications are case-by-case, and universal standards are difficult to impossible to design, you often roll your own - which is exactly why so many standards exist!

There is no need to feel any guilt in doing your own design, and it's often best to ignore irrelevant people who demand you follow some - almost always totally irrelevant - trendy standard. Most often, they have no clue what they are talking about since they never get anything done.

Lean, simple standards are best. And of course, sometimes it just happens there is an application-specific higher level standard that happens to suit your need directly, but sadly, this is rarely the case, and hence, you end up designing a yet another new standard.

Some sane recurring patterns make sense, however. Things like how you provide framing to low levels that provide inadequate framing (such as UART with 8-bit HW framing, inadequately small for most practical messages). In this case, I think it's a sign of good design that these things only take a few dozen lines of code, are portable, and don't require a heavy-weight library or a complex parser. Think about a complete opposite to what XML is, for example.

Beware of the "ASCII is easy" trap, often touted in these forums as well. I have seen countless of totally broken designs and complex-as-hell parser needed just because someone thought ASCII provides framing "the easy way". The fact that most terminal equipment, PCs and libraries corrupt and change line feed symbols alone breaks so many implementations that rely on these symbols for framing. I often use ASCII anyway, but the parser is almost always at least 200-300 lines on both sides. Sometimes a simple binary format is one tenth of the complexity.
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Typically, i want check: leakage HV diodes, capacitors, resistance of PCB, quality of coating for HV circuits. It very important for me, because i make many different HV converters powered by small battery.

In future i have plans for low voltage and low current circuits.
Nice, keep us posted with some pictures, of how it works out.


But im doing all this on the cheap. You guys probably have cables that cost more than my whole setup.

If you look long enough on ebay and other places, good deals can be found.
But in general, these parts are ultra expensive.

Buying full length cables and cut them in half to make some adapters
also safes some money.


And yes, even after a while of usage, the Keysight B2987A is horrible.
But it can be easily controlled by remote software.

Unfortunately, I can confirm it :(
I think the day will come that I will sell the Keysight B2987A and get a new Keithley 6517B instead.




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Fancy but not really my cup of tea. I like a cavernous cargo area, nothing I've found quite matches the utility of the classic Volvo turbo wagons. Just enough performance to be fun, with the ability to haul furniture or camping gear. This is going off topic though.
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Microcontrollers & FPGAs / Re: [C] Pointers - what is the point?
« Last post by rhb on Today at 04:44:22 am »
I think a somewhat more canonical form is:

char *strcpy( char* to, const char* from){
    for (char *ptr = to; *ptr++ = *from++; )
        ;

    return to;
}

possibly, but I was trying to explain this to a novice. 

However, I do not consider it good style as you have to pay close attention to the punctuation or it will be wrong. It also leads you into an area where the standard states the behavior is undefined or implementation dependent.   The compiler will generate almost exactly the same code for both versions.  And with optimization turned on they would probably both produce the same assembly.
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General Chat / Re: I thought airport's made lots of $$ (now I'm stumped..)
« Last post by rdl on Today at 04:42:20 am »
Jaguar C-X75

With the mirrors and lighting reversed, that car would look almost as good going backwards.
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