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, <100 MHz, the Aries "Correct-A-Chip" series is what I use. The adapters seem pricey at first, but because they are solder masked, they are easier to solder and desolder and can be reused several times (www.arieselec.com/products/correct.htm). Models 08-350000-10 and 14-3500000-10 are available from DigiKey and Mouser. I have used these well into the hundreds of megahertz with op amps (with the expected peaking), but I would not try them on fast, high-current switchers or other LC RF-critical applications where extra lead inductance and capacitance could be lethal to the circuit. But for low-power, low-speed apps, they are all but invisible.
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! rap@galaxy.nsc.com —or: Mail Stop D2597A, National Semiconductor P.O. Box 58090, Santa Clara, CA 95052-8090
We've always had the groundrule to breadboard anything analog, but SMD really does hamper the process. Some like breadboarding on PCBEXPRESS-like PCBs - its cheap and you can go into it with variations on the design at the start. Of course major design changes mean starting over, but it is still fast and cheap. Forget the BGAs though.
Hammmster -August 19, 2005 (Article Rating: )
With regard to Mr. Weiner’s question, I was asking myself the same questions a little over a year ago when I headed down the prototype-road myself. I found the surfboard and correct-a-chip products, however there is one other alternative to consider for the lower frequency stuff. You can also purchase programming/test adaptors that convert a surface mount socket to a DIP footprint. One source is Logical Systems (www.logicalsys.com), they also have the correct-a-chip type adaptors. These socket-based adaptors are probably more likely to cause problems with parasitic LC effects, given the extra metal and the twists and turns it takes to form the socket. They do however, offer the ability to switch chips in the blink of an eye with a virtually unlimited number of swaps. They are rather expensive, but none of this stuff is cheap. If you have the time, you can make your own such adaptors at lower cost. One source for sockets is Emulation Technology (www.emulation.com), they also have some other prototyping related products. Once you have the socket, all you need is some FR4 and breakaway pin-headers. Also, it should be noted (if its not too obvious) that you pretty much need a lighted magnifier at the least and preferably a binocular microscope for they really small stuff. Its all very expensive, but so are GHz range scopes.
All in all, the benefits of surface-mount technology far outweigh its costs in prototyping budgets and eyestrain. Still, one can’t help feel a little frustrated at having to gain the skills of a jeweler on top of the skills of an engineer. Out of my frustration, I have even taken to coming up with some alternate acronym translations for some of the surface-mount parts. For example:
SOP = Squint Only Periodically MSOP = Microscopic TSSOP = Terribly Small, Soldering Operations Precarious QFN = Quite Frustrating Now TQFP = Terrible Quandary Finding Pins BGA = Better Get Aspirin SOT –23 = Somewhere On Table, 2 maybe 3 of them
Its silly I admit, but I figure its better to laugh than cry.
Scott Morrison -June 30, 2005 (Article Rating: )
Your Comments:
Enter the text from the image below
Please refresh the page if you have trouble reading this text.
Search Electronic Design
Email Newsletter
Sponsored By:
Electronic Design UPDATE provides readers with late-breaking news, opinions from industry experts, and timely technology stories. It's a unique opportunity to get your product message in front of engineers, engineering managers, and corporate managers while they're reading about critical information online.
Reprints
)
