Getting En from NV

That datasheet is total nonsense. How does one measure "Noise Frequency" in dB? And I have no idea what the 15 mV "noise voltage" might mean, and I suspect they don't, either.

Doesn't NTE sell floor sweepings into the repair market?

John

Who *are* NTE anyway and why do their products get mentioned in ngs so often ?

Graham

Hi, Graham. NTE is the largest seller of general repair parts for radio, television and consumer electronics.

They don't manufacture much of anything -- they get representative parts and have their house (NTE) number printed on them.

Several advantages to NTE parts here. First, if you live close to any metropolitan area, you can get it *today* -- that can be important if tomorrow's too late. They have many local distributors through the TV/Radio/consumer electronics repair network. If you live, say, in Chicago, you can just drive to one of many different sources, and get these parts until at least 7:00pm on weekdays. This has saved me many times on ultra-urgent prototypes, when tomorrow's too late.

Second, in order to minimize the number of discrete semis they carry, they purchase standard parts and have them tested to a sometimes more rigorous spec, so that the one part can be a substitute for many different discrete transistors or diodes. You just look up the standard part number in their cross-reference to get the NTE number. The cross-reference is available in their catalog, or on their website.

Third, they're good at getting in end-of-life buys, so if you need a small quantity of something that's been obsoleted, you can look there before going to a broker. They generally charge about what a broker will, and their parts are top quality. Brokers, sometimes not so much.

They also carry resistors, caps, and a line of techie stuff, and are good guys -- except that they charge premium prices, of course.

But if you need it NOW, that's no problem. I find it to be a good last chance source for engineering prototype parts, especially transistors and standard ICs. For a hobbyist, getting these parts can be as simple as driving down to the local TV repair shop.

Their data sheets do occasionally have errors in them, as this one apparently does.

Cheers Chris

Based on the noise figure data, the correct noise voltage numbers are 0.15 and 0.2 uV.

This is consistent with a low noise J-fet like the 2N5459.

....... Phil

Often I use a reverse NTE cross reference ->

, but sometimes that website doesn't know the reverse part; e.g., for NTE458 they merely show "N-chan JFET"

You're right Chris about NTE being quick and convenient. I just wish they would easily supply the reverse part #. Personally I usually find NTE's datasheets lacking a great deal. So it's not like I want to find the reverse part # and buy from another manufacturer, but that might be nice. ;-) Usually I need to see a detailed datasheet. Is there a way of finding all the NTE reverse cross reference part #'s?

Paul

Hi, Paul. Reverse cross-referencing would probably be about the worst thing for their business model. Once or twice over the years, I'll admit to flipping through the 2N and 3N pages of the cross-reference catalog, looking for the NTE or ECG number so I could substitute something I had on hand. (O shame! O indignity!)

If you take the time to figure out what's going on in the circuit, you can pretty well figure out what part you need. And that should take less time than flipping through the pages. But on the other hand, if you're repairing an old engineering prototype without docs that has an ECG or NTE part, that may be a valid choice if you're in a big hurry.

On the downside, the NTE cross isn't always perfect. It usually works

-- not always.

If you buy the concept that you're replacing a part with a guaranteed "as-good-as" or superior part with NTE, you're accepting that going the other way may very well result in your replacing with an inferior part.

And even if either of two parts can be replaced by one NTE part, that doesn't necessarily make them equivalents to each other. (Try using translation websites to go, say, from English to German, and then back again. Note the potentially hilarious results. Not so hilarious if your fix doesn't work.)

But the concept of a reverse cross-reference is a pretty good one, I'd guess. You might have to scan in all the pages of the cross-reference, then plug the data into a ginormous spreadsheet. And of course, if you ever tried to sell it, NTE would come down on you like a ton of bricks.

Cheers Chris

The datasheets are vague so that they can buy whatever's cheapest this week, stick their number on it, and sell you that.

You can buy real parts, with real datasheets, from Mouser or Digikey, only cheaper.

John

I just sort a lot of leftover semiconductors by the ECG/NTE cross reference and see what I have on hand when I need a part. If a drawer fills up, I sort it out by part number of anything I find more than a dozen or so, and put them into their own drawers. Of course, I have over 20, 50 drawer parts cabinets full of sorted parts.

The bad thing is that they delete a cross reference when they obsolete a part number, so you may have the part in stock, but its no longer in the book or software.