DIY SIP OTA

[R.G.]

I saw a reference to a SIP OTA from somewhere impossible to find. It sparked an idea that I'd used back when I was an engineerling.

An LM13700 is almost a SIP OTA.

All's you gotta do is bend the leads on the pin-1 side out straight to the side, and clip off every pin on the other side **except** pin 11. Now you put the new-ly minted SIP package into an inline row of holes, and use some wire-wrap wire to connect the now-topside power pin to the PCB.

[puretube]

cool!
brings up a new idea:
bend up all pins,
and use a sandwich PCB on the second row side.

That matches Mark`s demand of having space for
componenets left & right of the pins...
(low profile, of course).

[Mark Hammer]

Now that's clever.

When our former Ottawa (now Tokyo) buddy Osamu Hoshuyama paid a visit back home to the family a few summers back, and brought back some delights from the Akihibara, he brought me a BA6110, which I've been saving up for just the right occasion, sorta like a fine cigar or bottle of wine.  Having more devices like that by simply tilting a dual OTA on its side  is a great idea.

Incidentally, if one is willing to run a wire up to the V+ pin, couldn't one do the same thing with either dual or quad op-amps?

[R.G.]

Incidentally, if one is willing to run a wire up to the V+ pin, couldn't one do the same thing with either dual or quad op-amps?

Sure. Anything that has independent sections on either side of the chip.

I once did this with a CD4049 to get a triple hex inverter in a SIP package.

You have to be sure that the chip is really OK with the pins open though.
In the case of the 13700, it's true.

[Peter Snowberg]

Cool idea R.G.!

cool!
brings up a new idea:
bend up all pins,
and use a sandwich PCB on the second row side.

That matches Mark`s demand of having space for
componenets left & right of the pins...
(low profile, of course).

Hehe... Seymour Cray used that sort of design for the CDC6600, the first supercomputer. Later he left CDC (Control Data Corp) and founded CRAY Reasearch.

Seymour called it "cord wood" packaging because if you look at the modules from the side, the resistors look like a pile of logs between two phenolic walls.

Google is an amazing thing.... Here's a picture of a 6600 module
http://research.microsoft.com/users/gbell/craytalk/sld034.htm

[R.G.]

Supercomputers and Japanese toys get all the fancy packaging.

The TI STAR supercomputer was made from 14 pin and 16 pin dual in line packages of TTL logic. The pin rows of these are 0.300" apart. They noted that if you drilled holes in a PCB every 0.100" inches solid, that you could mount DIPs on BOTH sides of the PCB solid, so that every single hole was filled with a component lead and the entire surface of the PCB was covered in epoxy packages.

They soldered them by putting solder ringlets on each pin of the ICs and crimping the ICs in place on both sides, then dipping the whole board in boiling peanut oil to reflow the solder. The working yield for this process at getting every single pin of the thousands on a board soldered correctly was 5% - one board in 20 worked correctly after soldering. That was considered a good yield since the supercomputer prices were then so high that it was worth it to throw away 95% of the raw materials to get such dense packaging.

[Joe Kramer]

Lateral thinking in the true sense of the phrase!

Another trick along the same lines:  if you're ever in a pinch for a SIP dual op amp (or want to try subbing something not at hand) you can use a quad op amp with half the pins cut off (except the pos or neg pin), same as RG suggested with the OTA. . . .