ORIGINALLY PUBLISHED IN LIMA NEWSLETTER SEPTEMBER 1993 POWER YOUR ENTIRE TI SYSTEM ALMOST ANYWHERE WITH AN INVERTER by Charles Good Lima Ohio User Group In the June, July, and August 1989 issues of Micropendium Jan Janowski had a series of articles describing how to run a small TI system in the field powered by a small 12 volt battery. (The articles originally appeared in the Chicago Uaer Group newsletter.) Jan's "portable TI" included 32K, PIO port, and a ramdisk all in the console. There were no disk drives. All this required much complicated custom wiring and soldering. There is an easier way. With NO MODIFICATIONS WHATSOEVER you can run your entire TI system (console, PE box full of cards and two floppy drives, small monitor, and maybe also your printer) for between 30 minutes and several hours powered by a 12 volt automobile or (better) deep cycle battery. All you need is an appropriate inverter! Inverters convert 12V DC current into 117V 60 cycle AC current. Any AC product can be run from a 12V DC power source such as a battery with a modern inverter. Inverter technology has improved considerably in the last 10 years. Old style inverters were very inefficient (50-60%) and produced "square wave" AC which is unacceptable to most electronic devices such as TVs stereos, and computers. Modern inverters produce "modified sine wave" AC which is acceptable to almost everything electronic including TI99/4A equipment. One manufacturer now offers a true sine wave inverter said to be compatible with the most sensitive electronic equipment. These modern modified sine wave and full sine wave inverters are 80-98% efficient and dwaw only very small amounts of power when on standby. The STATPOWER PROWATT 250 is a 90% efficient modified sine wave inverter will power a complete TI99/4A system from a battery if you use a small monitor such as a 4" B&W TV. The STATPOWER 250 will deliver the following AC current: 500 watt surge, 300 watts for 10 minutes, 250 watts for 30 minutes, and 200 watts continuously. Output voltage is very well regulated at 60 cycle and 115V +- 5% until automatic shutdown if the battery voltage gets down to 10V. This is better voltage regulation than the power company provides! Just plug in a multiple plug power strip into the single female 3 hole outlet at the AC end of the inverter, and plug the TI99/4A components into the power strip. You can run a console (40 watts), a full PE box (150 watts), and a 4 inch B&W TV (16 watts) on the STATPOWER 250 powered by a car battery. I have done so. Run time is is at least 30 minutes and may be greatly extended if you have a "switching power supply" in the console or if your small TV doesn't need the inverter because it can be run directly from a 12 volt source. (My small TV draws 16 watts AC from its inefficient (always warm) AC transformer, but draws only 9.5 watts when powered directly from a 12 volt battery). The main limit to run time is the power stored in the battery. If you use a 100 amp hour deep cycle battery (commonly available at department stores like Sears, Walmart, and Myers) where electric fishing "trolling" boat motors are sold), you can run all the above computer equipment for over 4 hours without discharging the battery more than 80%. Unlike automobile starting batteries, deep cycle batteries are designed to acceppt 80% discharges repeatedly (200+ times) with no significant loss of battery performance. The STATPOWER 250 has a cigarette lighter plug and can be pluged into a car's cigarette lighter. However, most automobile lighter plugs are fused at 10 amps DC, which means a maximum of 120 watts of power is availeble from this source. To run a PE box equipped 99/4A you need to cable the STATPOWER 250 directly to a battery. The necessary 1 foot cable for car battery use with clamps for the + and - battery terminals on one end and a female cigarette lighter plug at the other end is available from Radio Shack, WalMart, and many auto supply stores. As of early August 1993 catalog prices for the STATPOWER 250 vary from $198-$229 plus shipping. It is available from REAL GOODS (phone 800-762-7325) or SUNELCO (phone 800-338-6844). Phone these dealers and ask for their catalogs. They both sell inverters of larger and smaller capacity and both dealers can also set you up with a solar panel to charge the deep cycle battery you will use to power your TI system at remote locations. Smaller STATPOWER inverters not powerful enough to run a full TI system have recently appeared in the C.O.M.B. catalog. These smaller inverters can be used to run small AC electrical devices from a car's cigarette lighter. 140 watt AC continuous, item P3522-9506, for $70. 125 watt AC continuous, item v3661-9505, for $70. 50 watt AC continuous, item v3662-9505, for $50. C.O.M.B.'s phone is 800-328-0609. PL 1