Who wanted some 709 op amps (obsolete)? whyterabbyt?

...and how to do so...
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A few years back I sent off what I thought were my last 709 op amps to someone -- maybe whyte? -- who needed them for a musical electronic project that wouldn't work with 741s or other chips. The effect depended on some characteristic of this older design. [edit: IIRC they never reached their destination.]

Well, I found more. Most were in TO-5 cans; over a third of a century, their leads corroded right in the block of conductive foam I used to "protect" them. All trash now. But there are three in 14-pin dual inline packages that look okay, except for bits of (apparently less corrosive) conductive foam sticking to the pins. That can be brushed or scraped away with some time and care.

Anybody want 'em? Yours for the cost of postage. Note that unless you need 709s for a specific circuit they're probably not worth that much.

[moved from OT to Hardware because ISTR they were to be used making Kraakdozen.]

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Bump. Foam cleaned off using a low-speed Moto-tool and soft steel wire brush. Now they look fine, though I've not tried wiring them up to see whether they work.

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Meffy wrote:Bump. Foam cleaned off using a low-speed Moto-tool and soft steel wire brush. Now they look fine, though I've not tried wiring them up to see whether they work.
I could use a few...I'll PM you
Barry
If a billion people believe a stupid thing it is still a stupid thing

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Out of interest - does anyone know what would make them a must have for a project apart from reproducing a vintage circuit? IIRC, they HAD to have a comp cap.

I used to work on a data tape head board that used a 709 and we had one that insisted on oscillating no matter what was checked and changed - even the designer couldn't fix it!

BTW, I work with some stuff that still uses the equally venerable 710 comparator.

Cheers
Jim

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Hi, Jim. I couldn't tell you why the circuit won't work with a 741 or whatever. My analog design days are too many decades in the past. However, I am going to try to relearn what I knew and learn what's happened since.

Whyte doesn't want any, trimph does. What I think I'll do is get substitute transistors, put together a breadboard version, and test all three ICs. If they all work I'll keep one, send the other two to trimph. If someone else steps up I'll split them between you. If just two work I'll give trimph one and keep one, and if just one works trimph gets it plus whatever parts I picked up to test them -- enough to make one Kraakdoos.

If none work I'll send them all to the next spammer to reply with his or her bank account details.

Seems fair.

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