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Thread starter #1
Hey everyone,

I have here an opamp (I believe), made by PHILBRICK/NEXUS, part number SQ-10a.

There are 7 pins, labeled "-IN", "+IN", "+15", "COM", "-15", "OUT", and "TRIM".

The Google doesn't show any datasheets for this. If anyone has ran across this little gem in the past and has a datasheet, I would greatly appreciate it.



It is indeed an op amp. Most of my databooks and datasheets on this kind of thing are at the shop, but the part was a lower-cost general purpose op amp I think and I'm guessing that its specs weren't all that much different from, say, a 741. It uses standard analog supplies of +- 15 volts and you'll notice it has a ground (common) pin. This was pretty much the rule in the early days of op amps. Even the first analog IC's had ground pins: The 702 op amp, the 710, 711, 720, 820 comparators and others had ground pins. For the trim pin, generally you would connect a resistor, maybe a rheostat-connected pot, perhaps 50k or so, from the negative rail to the trim pin.

I don't know what the input common-mode and differential voltage ranges were or if the output is protected or not. If you are wanting to fire it up and the pins haven't been soldered to, there are plenty of nice ways to connect to them without goobering them all up with solder. If they're still pristine gold-plated pins and you don't want to scratch them up with socket connectors, you might use wire-wrap wire and wrap them by hand. The pins are round, of course, and too big for a wire-wrap tool. Wrap with at least an inch of wire. I would then slide something like a piece of insulation from 14 ga wire or maybe some heat-shrink down over it. (This was called "spaghetti" in the far-flung days of yesteryear.) I would leave the heat-shrink unshrunk, though. If it's tight, you (or someone) may have to cut it and scratch or damage the pin. There were standard sockets available, too, by the way.

I haven't been to the shop for a few days. It's been 20 below here for a few days and I've been working from home. I should get down there in a day or two, though, and I'll try to find the datasheets for these things.
Dave Graen


Well-Known Member
Nice bit of history. I was surprised to see a chopper stabilized amp with a BW of 16 MHz. Pretty Cool stuff.


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Most Helpful Member
The whole website is. Looking for the datasheet won't get you anywhere. I wish I was able to find a long time back, like maybe a decade when I was working on this: http://www.vesco-usa.com/XYS-8 Sweep.pdf It does look like they made a replacement with an OP Amp and a resistor. I very briefly tried to help someone repair this particular board. That datasheet probably would have helped a lot. My time was needed elsewhere.

When I was browsing the internet, I knew it was on that site somewhere, so one night I decided to find it.
A long time ago I used to work with those op amps. I had received a box of samples of nexus op amps of various types from a dealer. The pinout on the label and the Burr Brown Operational Amplifier Handbook: http://www.ti.com/lit/an/sboa092b/sboa092b.pdf got me up and running with using them in experiments. Then my father dug up a short form catalog with pricing and I found these things I was playing with (and burnt up a few) ranged from $150 to $350 a piece. Inside is a collection of lab matched transistors to make an op amp.

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