Path: utzoo!telecom-request Date: 6 Jun 91 19:23:24 GMT From: Joshua_Putnam Newsgroups: comp.dcom.telecom Subject: Re: Cellular Modems Message-ID: Organization: Happy Man Corp., Vashon Island, WA Sender: Telecom@eecs.nwu.edu Approved: Telecom@eecs.nwu.edu X-Submissions-To: telecom@eecs.nwu.edu X-Administrivia-To: telecom-request@eecs.nwu.edu X-Telecom-Digest: Volume 11, Issue 435, Message 3 of 11 Lines: 43 In dplatt@ntg.com (Dave Platt) writes: > In article is written: >> Seeing as how a car battery can provide a substantial amount of power, >> I was wondering if anyone knew of any product that would allow us to >> run something like this off of the car's lighter jack, or even to hook >> directly to the battery if necessary. Or of any portable with that >> much power and a slot that you can take along with your cellular >> phone. > If you want to run a laptop, cellular, etc. from an auto's electrical > system, you'll probably have to buy an external high-amperage 12-volt- > to-5-volt stepdown regulator (probably a switcher, with extensive > surge protection and some big filter capacitors), and a "cheater" > which will let you plug the regulator's output into the laptop's > charger input or directly to the battery-compartment contacts. A power inverter (like the guts of a UPS) will turn your 12v DC into 120v AC, letting you use your standard AC adapter. Not very efficient having so many power conversions, but probably one of the simplest to plug together. You could use it in a car, or with a separate 12v battery pack. You'd probably want to be sure the inverter produces a regulated sine-wave output considering the fluctuations in the car's electrical system. Some of the cheaper inverters produce noisy square wave power with no regulation or filtering. I don't think I'd want to run my computer on that. I can't recall the brand name, but I've seen lots of ads lately for a fairly compact 100 watt inverter that plugs straight into the lighter socket of a car. For any load larger than that, I wouldn't want to trust the car's standard wiring. If you always drive the same car, just install a 500 watt inverter and put a 120v outlet in your glove box. :) Watch out for dead batteries, though. Joshua_Putnam@happym.wa.com Happy Man Corp. 206/463-9399 x102 4410 SW Pt. Robinson Rd., Vashon Island, WA 98070-7399 fax x108 E-mail: patty@happym.wa.com