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Pease Porridge
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408 results found for Pease Porridge, displaying items 1 - 20
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June 30, 2008
Bob's Mailbox
Analog and power guru Bob Pease corresponds with readers about the latest proposals for electric cars in this exclusive online edition of his popular mailbag.
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Bob Pease
June 26, 2008
Bob's Mailbox
HI BOB, I have been collecting some new but mostly museum-grade test instruments. Along with purchases from various instrument rental houses, flea markets, and so on, for a while I bid on items in government liquidation auctions. Occasionally, I won. The starting bid was always $50, and some I got at that price. Some went way higher but seldom approached the original list price, and I gave up way before that. Often, the shipping costs to a pickup and forward...
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Bob Pease
June 12, 2008
What's All This Current-Source Stuff, Anyhow?
Recently, a guy asked me how to draw a constant 1.00 mA from a node of a circuit. Of course, he did not tell me what volts, ohms, or frequency. But, he admitted, he basically did not know how to design a current source. So I’m sorry to waste the time of all you guys who do know how to design a current-source. But maybe this lecture can help and save you some time so you don’t have to teach all the young kids. If you need a current source, and you don’t know ...
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Bob Pease
May 27, 2008
Bob's Mailbox
Check out these additional letters to and answers from electronics guru Bob Pease.
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Bob Pease
May 22, 2008
Bob's Mailbox
HI BOB, Any big trips to exotic spots planed this year? We’re headed for Newfoundland and Prince Edward Island for a change of pace. (I may go to Scotland in September. /rap) My question: Do you have some circuitry I could use for an electronic bagpipe simulator? It would need nine notes selected by removing fingers from some form of contact that would reasonably simulate a finger hole. I don’t need too many...
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Bob Pease
May 8, 2008
What's All This One-Transistor Op-Amp Stuff, Anyhow?
One day, back about 1966, I was going up the elevator at 285 Columbus Avenue in Boston to look at some production problems on Philbrick’s fifth floor. And who was in the elevator, but George Philbrick’s friend Jim Pastoriza. Jim was going up to show George his new analog computer demonstrator—portable and battery-powered. In fact, it was running, and he gave me a demo right on the elevator as we ascended. And, this modular analog computer ran on a couple of...
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Bob Pease
April 24, 2008
Bob's Mailbox
HELLO BOB, A note concerning electric cars and plugin hybrids: Consider that politics has little to do with engineering and/or science. It only pays lip service at those altars. So, somebody has to do serious planning for the immediate future. I’ve been working on some serious battery-charger designs. One of our planners (an engineer) did some research in good old California. We learned that your utility companies have ...
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Bob Pease
April 10, 2008
What's All This AMT Stuff, Anyhow? (Part 2)
I’ve often heard that if you’re going to owe the Alternative Minimum Tax, there’s nothing you can do about it. And that makes me scream! Most of these officious statements say you can postpone some income and defer the AMT, but you’ll just pay them next year. “There’s nothing you can do to avoid the AMT.” It’s a lie! I was absent-mindedly reading some of the boilerplate on some of my other investments. “You might like to buy some AMT-free bonds,” Dreyfus...
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Bob Pease
March 27, 2008
Bob's Mailbox
HI BOB: I would like to ask about designing a sinewave amplitude attenuator with programmable attenuation. Preferably, it will just contain basic components (op amps, transistor, resistors, caps, etc.). Input: 1-V p-p sine wave (1 kHz frequency), symmetric at 0-V level. Desired output: still at 1 kHz, but the amplitude varies from 0 to 1000 mV. –JOERICH SUNICO HELLO,...
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Bob Pease
March 13, 2008
What's All This LED Power Stuff, Anyhow?
Recently, NSC put on a webcast with Howard Johnson, NSC’s Chris Richardson, and some guys from Philips and Future. As they had set it all up and presented it at the last minute, I didn’t know what points they were going to make. When they made their pitch, it all made perfect sense—but I wasn’t prepared to contribute very much. I sat there like a “fifth wheel,” not making many comments. But I did set up one experiment, which wasn’t shown on the webcast. I...
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Bob Pease
February 28, 2008
Bob's Mailbox
DEAR RAP: You answered one question for me last year (“Why are FETs so expensive in India?”), and I now have another. How does a bipolar op-amp-based non-inverting dc amplifier amplify dc signals that are below a 0.6-V bipolar threshold (e.g., an LM358- based non-inverting dc amplifier)? (Okay, you want a gain of +1.5 or 2 or 3 for a small signal that is barely above ground, such as +0.1 or +0.2 V? And the LM358 uses a small...
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Bob Pease
February 14, 2008
What's All This Oscillator Stuff, Anyhow?
Anybody can make an oscillator these days at almost any imaginable frequency. But how do you make a good one at low power? A couple of people recently asked me why I add so much complexity by using an op-amp oscillator in my Cold Toe Detector. (That general-purpose slow oscillator is in the LH upper corner of www.national.com/rap/coldtoes.html.) "What kind of analog freak are you?" they asked. "Why don’t you just use a CD4060, which has a built-in oscillator?" I responded that everybody...
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Bob Pease
January 31, 2008
Bob's Mailbox
DEAR EDITOR: At first I thought I picked up an April Fool issue, but no, you have Al Gore in the Tech Year in Review section honoring him for imploring engineers to turn green (Dec. 1, 2007, p. 45; ED Online 17958). What crap. Please cancel my subscription. –"RAY" Hello, Ray: There are several reasons to “turn green,” and Al Gore’s bleating about warming theories is only one of those reasons. Energy is expensive. Or haven’t you...
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Bob Pease
January 17, 2008
What's All This Layout Stuff, Anyhow?
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Bob Pease
December 13, 2007
Bob's Mailbox
Bob: While my full-time job is writing for Electronic Design, I still teach part-time and work on an NSF grant that is attempting to update the electronics curricula in community colleges. From my observations in my own college and across the country, most curricula are out of date with what is going on in the industry. (True, but not disastrously bad. We canâ??t ask that education for techs or for EEs be really up to date. That has almost always...
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Bob Pease
December 3, 2007
What's All This "Best Trick Circuit" Stuff, Anyhow?
Once upon a time, op amps didn’t swing very close to the positive or negative rails. Even a couple volts away from the rails—that was okay in the old days of transistor-ized op amps. Hey, that was a lot better than with vacuum-tube op amps that wouldn’t swing within 200 V of the rail. Some op amps could do a little better, but customers never asked us for better 35 years ago. The LM324 can swing pretty close to ground (–VS) if you have a...
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Bob Pease
November 15, 2007
Bob's Mailbox
Bob: In “What’s All This Capacitor Leakage Stuff, Anyhow?” (March 29, 2007, ED Online 15116) you have a diagram of a test circuit using the LMC662. This circuit is quite a bit different from the “capacitor soakage” test circuit you referenced on your Web site. (After you get the capacitor charged up, and after you get the soakage elements charged up (which takes hours and days), the rate of change of VOUT is caused by the leakage, which you cannot really see until...
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Bob Pease
November 5, 2007
What's All This Stability Stuff, Anyhow?
A guy recently asked me how I would look for a voltage reference that's stable versus temp cycling. I told him I would take several of the best voltage references I had and use a dual-slope DVM of at least six digits to compare them to the units in question. He then asked if comparing some references to some other ones was kind of incestuous. This is not rocket science. You take several good voltage references and leave them the heck alone! Apply some bias and just...
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Bob Pease
October 25, 2007
Pease Porridge
Bob: As we were landing at O'Hare Airport last week, I was observing the runway and taxiway lighting. I immediately noticed that the lights are now LEDs. Would you believe that even these are designed to operate off the standard 6.6-A constant current system? (See www.flightlight.com/airportlighting/ 1.1/1.1.2.html.) This fixture is rated at only 3 W, which means it apparently drops 0.5 V at 6.6 A (perhaps 1.0 V or more with transformer losses?). There is still a power...
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Bob Pease
October 11, 2007
What's All This Safety Margin Stuff, Anyhow?
Sometimes it's easy to tell if you have a safety margin. With a voltage regulator, or any linear amplifier, if it was oscillating, you could add a fix - often, a simple series R-C network from the input or output to ground. Good. But is it good enough? To be safe, you should put in a square wave of voltage (or pull out a square wave of current through a little R-C network) and make sure that there isn't any bad ringing. Now, to be quite sure, you would have to...
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Bob Pease
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