Electronic Design

Bob's Mailbox

Hi Bob: Does anyone breadboard circuits anymore? In the good old days, just a few years ago, you used to draw circuit diagrams in your articles that looked like something a college professor would put up on a white board. We design engineers would all run out to the lab and try it out in a couple of hours.

I always seemed to get more out of actually trying out my more complex circuits than from simulating them.

However, today a lot of the newer, exciting ICs come only in such small packages that even a neurosurgeon would be hard pressed to hook them up. Have you ever tried to solder wires to a quad op amp in a 14-pin, small-outline IC (SOIC) package? Have you seen the packages that these three-pin precision voltage references come in? If you sneeze—game's over? I'm all for miniaturization, but not in the breadboard stage. Not all of us are working in the gigahertz range where lead length is critical. Have you ever soldered #36 wire to one of these parts and then to an old-fashioned DIP socket—so that you could wire wrap to it?

I recently got a sample kit of op amps from one of the major IC vendors. It has some really neat parts. The largest package was an eight-pin SOIC. To add another level of complexity, they included tape and reel parts. I mean, come on, how do you build breadboard circuits with fly-spec parts? (With perseverance—or with adapters. /rap) Are there any inexpensive chip carriers that convert these parts to fit into an old-fashioned DIP socket? Does anyone out there have a solution, other than laying out custom pc boards every time you want to breadboard a circuit?

Dick Weiner (via e-mail)

Pease: Yes! Let me find you the standardized answer from Paul Grohe. DigiKey carries them. For non-gigahertz applications, these are good, and they have solder-mask, so they connect up and don't short out.

Paul Grohe: Hi, Dick. For SO-8/14-to-DIP conversion,

For SOT-23, SC-70, MSOP-8, and other nasty little "transistor" packages, the Capital Advanced Technologies "Surfboards" can be used (www.capitaladvanced.com). These adapt SOT-xxx to a 0.1-in. spacing SIP. They do not have solder mask and don't tend to last as long, but they are a bit cheaper. They are available from DigiKey, Newark, Fry's, and Jameco. By the way, you can "stretch" an SC-70-3 onto a SOT-23-3 footprint. So the SOT-23 adapter can do "double-duty" as an SC-70 adapter, too.

Hi Bob: I tried your stair-climbing idea (electronic design, March 3, p. 20) this morning instead of my usual Sunday morning outdoor downhill/uphill plod, as it was raining a bit here near Seattle, Wash. (Imagine that!) I decided to start with 50 laps and it took me about 20 minutes. Nice little workout. (Fifty is a pretty good start. When I was out of shape, I did 65—which is lousy—but it was a start. /rap) The only comment that I have is that I prefer a little 10-minute cool-down walk afterwards, just to gather my wits. Thanks for the suggestion.

Dave Gerstenberger (via e-mail)

Pease: My preference is to just lie there, but I guess I am used to that. While I am lying there, I can count my pulse rate (up near 150 bpm?), then wait two minutes and see if the rate dropped a lot.

Comments invited! [email protected] —or:
Mail Stop D2597A, National Semiconductor
P.O. Box 58090, Santa Clara, CA 95052-8090

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