Electronic Design

Bob's Mailbox

Hi Bob: In today's Wall Street Journal, there's a full article on A4 concerning hydraulic hybrids. It was developed by the EPA, which has a small lab. UPS trucks are being used for testing, but garbage trucks will be the first commercial use. (I wonder what the standard "driving cycle" is for a UPS truck. It must be quite different from the EPA cycle for cars. Many parts of that cycle might have a lot of stopandgo, but not all—not to mention the typical garbage truck cycle, which must be pretty wild. Gallons of garbage per gallon? But around here, garbage trucks already use hydraulics. So for their pickup cycle, they only need a small engine and a small accumulator. To haul to the dump, they need more power on the road.

/rap) Ford had been a partner but decided to go electric hybrid (with its Escape). This is good, but I feel that ultimately, electric is the most reliable, most efficient, and most elegant solution. Motors and controllers continue to improve (Oh come on! Electric motors and controllers have been very good for a dozen years. Even 100 years ago, they weren't bad. It's just the batteries that are overpriced or undercapable, regarding range and life. /rap) and even batteries (although I wonder about lithium). (Everybody says Sony's superior Japanese engineering and Chinese manufacturing expertise are always the best. I guess Dell found out different... /rap) Electronic Design had an interesting Techview on the Tesla Motors eCar (see www.electronicdesign.com, ED Online 13201). Now that looks like the future to me!

  • Dennis J. Eichenberg
  • Pease: You just tell me when the price of those lithiums comes down by an order of magnitude. I think that may happen quicker than fuel cells coming down two orders of magnitude in price, but I'm not holding my breath. Some idiots were prattling along about the upcoming fuel cells replacing batteries in laptops. What a bunch of poppycock! (And you do know the etymology of that word!) Okay, I am in favor of many ways to conserve energy in vehicle operation. Electric cars can do it. Hybrids with batteries and even (in concept) flywheels can do it. Fine. Hydrogen fuel cells as a hybrid with batteries? Great, if we can afford them. Supercapacitors? Well, fine, if they work. Now this morning on NPR, I heard about a new demo truck from UPS. It uses hydraulics and compressed nitrogen for short-term energy storage. The preliminary claims are a 70% savings on energy. Presumably this is for some urban cycle. Well, that's fine by me! Anything that works! /rap

Dear Bob: We've been soldering by hand for well over 50 years between my technician friend and I. (I've been soldering for over 50 years all by myself. /rap) We have tried several "new solder formulations that comply with RoHS and WEEE directives. The best replacement, from specifications and performance,-is the IA-423 formulation (Sn/Ag4.7/Cu1.7), which is eutectic like Sn/Pb37, and makes a nice clean-looking joint provided sufficient flux is used. This solder requires a nominal (10°C) increase in tip temperature or increased tip-contact time. Also working well is Kester's Sn/Ag3/Cu0.5 formulation. Although non-eutectic, this solder "wets" later than its leaded predecessors and flows through holes better than any leaded solder we've used. Final finish is not nearly as "cold looking" as some others. Both of these formulations work very well for hotair rework and assembly of surface-mount devices, which is even more critical than through-hole these days. It is worth noting that the IA-423 formulation falls under patent 5,527,628 (July 1993, USA Only), which covers the joints produced (SN/Ag3.5-7.7/Cu1.0-4.0), and the Kester formulation is patented (JP 50 50 289, March 1993). Non-patented alloys, such as Stannol TC (Sn/Cu1.0), produce the confusing, inferiorlooking "cold" final finish that was referred to in your June 22 column (see ED Online 12630). Perhaps there is some patent paranoia that is holding the lead-free world away from these quite usable alloys. (I will check them out. Thanks for the advice. /rap) I build my own prototypes to this day, even as a department head. I find soldering quite therapeutic.

  • Martin Mayer
  • Pease: I've been doing a lot of solder recently, and it still feels nice. /rap

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

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