What's so special about these op amps?

Question

I found these devices at the "swap shop" at our dump; not having any idea of what they were. I Googled them and found this:

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Summary: ? Bandwidth 12MHz ? Input Impedance 500M? ? Input Bias Current 1nA ? Input Offset Current 1nA ? Input Offset Voltage 0.5mV ? Gain 150kV/V ? Slew Rate 7V/µs

The data sheet has a 2006 date & there weren't many sites offering them,

but a couple that did had prices up to $43! Each! WTF? What makes these so dear? (It's probably obvious, but not to me, if so please excuse my newbie-ness.)

Bob

Tim Williams · Accepted Answer

2902, isn't that a variation on the LM358 (158/258/...)?

Price doesn't mean much, could be scalpers trying to scam people on availability.

Tim

-- Deep Friar: a very philosophical monk. Website:

formatting link

Summary: ? Bandwidth 12MHz ? Input Impedance 500M? ? Input Bias Current 1nA ? Input Offset Current 1nA ? Input Offset Voltage 0.5mV ? Gain 150kV/V ? Slew Rate 7V/µs

The data sheet has a 2006 date & there weren't many sites offering them, but a couple that did had prices up to $43! Each! WTF? What makes these so dear? (It's probably obvious, but not to me, if so please excuse my newbie-ness.)

Bob

Jim Thompson · Answer

Dear?  Because they're no longer made and probably because some audiophool thinks "they're pretty". The only unusual thing is the input bias scheme _cancels_ out (pretty much) the input current, thus the claimed "hi-Z". 		                                         ...Jim Thompson --  | James E.Thompson, CTO                            |    mens     | | Analog Innovations, Inc.                         |     et      | | Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | | Phoenix, Arizona  85048    Skype: Contacts Only  |             | | Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | | E-mail Icon at  |    1962     |               I love to cook with wine.     Sometimes I even put it in the food.

bloggs.fredbloggs.fred · Answer

There MIL-SPEC parts so the price is jacked through the roof. Now you know  why the government is broke.

Joerg · Answer

Most likely because in this day and age a TO-can for an opamp makes it a boutique part, just like a ceramic DIP package would. Maybe there were also some incantations, those can be expensive :-)

Vladimir Vassilevsky · Answer

Vsupply max = 45V. A feature of old technology rather then intended high  voltageness. VLV

Joerg · Answer

You don't need such a dinosaur for that. I used a 44V opamp from fresh production in a design lately, just a regular COTS part from ONSemi I think. If someone needs to know I can dig it out.

But that one doesn't come in a glass tube or TO can :-)

John S · Answer

Try to find one to buy. Maybe that will tell you something.

Tim Wescott · Answer

?

If you're building a replacement board for something military then you have to use the exact parts called out -- changing a part means you're redesigning the board, redesigning the board means you need to test it up the wazoo.

$43/ea can be a lot cheaper than the effort to verify that your chosen replacement part really does work in the circuit over temperature and whatnot, then to redesign the board to take a (probably) DIP package, then to formally verify that everything works, then to do all of the paperwork to upgrade the revision of the system that the board goes into, etc.

Bob Engelhardt · Answer

So, there's nothing special about what they do - it's just the mil  spec-ness and the rarity that costs so. Thanks, Bob

What's so special about these op amps?

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