Analog Devices AD741KH High Accuracy Op Amp TO-99 Metal Cap

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Smokedaddy
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Analog Devices AD741KH High Accuracy Op Amp TO-99 Metal Cap

Post by Smokedaddy »

Still playing with my 35mm Macrophoto. I wasn't sure how to remove the cap so I drew up a fixture and 3D printed it to hold the cap and used a parting tool on my lathe to remove it. Looks like I didn't get everything, o'well. I can still clean it up but I'm happy with the results so far. I could of taken a few more images for the stack too.

Much larger version here;

https://squattingdog.smugmug.com/Semico ... -CmhK9M4/O

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mawyatt
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Post by mawyatt »

That old 741 brings back memories :D I have used many of them, they were/are the most versatile OP AMP ever! Fullgar (sp) invented the ua741 at Fairchild and Bob Wilder tried to one up him with the LM101 at National. Then George Erdi came up with the ua725 precision version op amp using a "Cross Coupled Quad" layout which reduced thermal feedback, process variations and input device mismatch all at once. The layouts are done with Rubylith and Exacto blades backs then, Fond memories of those days :roll:

The large metal area is the feedback capacitor, 40pF I recall.

Very clever fixture to remove the TO-99 lid :)

And nice pictures too :)

Best,

Mike

Smokedaddy
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Post by Smokedaddy »

mawyatt wrote:The layouts are done with Rubylith and Exacto blades backs then ...
Image
-JW:

ChrisR
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Post by ChrisR »

I see the first Op-Amp was produced in 1941 :shock: :shock:
I met 741's 30 years after that. I was surprised/horrified to see they still get a mention on the current Electronics school syllabus!
Good job with the Lomo - and the parting tool. Somewhere I have one of those cans I made a mess of with a hacksaw..
Chris R

naturepics43
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Post by naturepics43 »

Larger image looks really good. If I may ask, what magnification and step size did you use.

Thanks,

Smokedaddy
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Post by Smokedaddy »

ChrisR wrote: Somewhere I have one of those cans I made a mess of with a hacksaw..
... I could of easily placed a piece of fine sandpaper on a surface plate and removed the cap. I have a tendency of over doing just about everything I do. <g>

-JW:
Last edited by Smokedaddy on Thu Dec 28, 2017 9:37 am, edited 2 times in total.

mawyatt
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Post by mawyatt »

Smokedaddy,

Large 6' square light tables with grids, wrapped with Rubylith sheets and drafting tools were the norm way back then, long before computers came into play :roll:

Chris,

Op Amps, or Operational Amplifiers, were/are a fundamental building block for analog computers, originals were built with tubes. They got their name from operational analog computations including summation, integration and differentiation, this was relatively easily with these devices. Burr-Brown and Philbrick are companies that come to mind in the early days of Op Amps.

Best,

Mike

Smokedaddy
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Post by Smokedaddy »

mawyatt wrote:Smokedaddy,
Large 6' square light tables with grids, wrapped with Rubylith sheets and drafting tools were the norm way back then, long before computers came into play :roll:
I was a manual draftsman in a few disciplines for 20 years or so up until I got involved with AutoCAD in the late 80's.

On another note, I would love to know how to intricately etch brass or aluminum cylindrically. I've been trying to find specific (like exact) directions for quite a few months. I did read about using PNP Blue but nothing intricate or cylindrical objects.

-JW:

Smokedaddy
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Post by Smokedaddy »

naturepics43 wrote:Larger image looks really good. If I may ask, what magnification and step size did you use.
I didn't figure out the magnification but I'm guessing approximately 3x (I'm math challenged to a certain degree). I think it was 141 images at 0.01mm increments.

-JW:

naturepics43
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Post by naturepics43 »

Thanks for the info. That little lens does a really good job.

Smokedaddy
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Post by Smokedaddy »

naturepics43 wrote:Thanks for the info. That little lens does a really good job.
I agree and probably even better results can be achieved with those with more experience than I have.

-JW:

mawyatt
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Post by mawyatt »

Well, you've certainly got a good start with your Canon 35mm macro!! That 741 chip picture is great :)

Smokedaddy
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Post by Smokedaddy »

Thought I'd make a stereo pair version. Best viewed with stereo glasses. A larger version is here;

https://squattingdog.smugmug.com/Stereo ... -C4pjGK7/O

Image

-JW:

BugEZ
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Post by BugEZ »

My first encounter with a 741 op amp was in 1970. There were rough plans in Scientific American for a seismograph. The op amp circuit was part of the detector feedback loop that drove the chart recorder’s pen. I cobbled it together with a clock motor to advance the paper and a slot-car motor to move the ball point pin. Amazingly after a few weeks of fiddling it all worked. I recorded earthquakes in China and South America. When I went away to college my dad kept it running for several years. His letters from home were often written on the back of the output tape. Fond memories!

Thanks for posting!

Keith

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