CURENT.100 by Tony Anderson 70506,1261 Public Domain Questions occassionally come up on the message board regarding the amount of current required by the Model 100. Bob Ripley, who edits a newsletter for a Richmond VA 100 owners user group, published a handy reference table showing the current requirements under various operating conditions. The chart was reproduced in the May 1985 issue of Portable 100/200 (page 48). Some highlights from that list: Condition: Current: 32K Model 100 off 1.2 ma 32K Model 100 on 57.1 ma Printer connected; off 89.5 ma Printer connected; on 59.1 ma Cassette Motor on 109.5 ma RS-232 cable connected 59.0 ma TELCOM (modem on) 150.0 ma Printer connected; off, TELCOM, modem on 183.0 ma Chipmunk connected 58.9 ma Barcode Reader on 98.0 ma Alkaline "AA" cells are generally rated at 1000 mah, which means the battery will (theoretically) provide 1000 ma for one hour, or 1 ma for 1000 hours. Expected battery life, for a fresh set of alkaline cells can be calculated by dividing the current drain shown above into the cells rating (in this case, 1000). Thus, a 32K computer, in it's normal "standby" condition, with no accessories connected, and nothing activated, draws about 57 ma; resulting in an expected battery life of 17.5 hours. Such figures are approximations, and depend on actual use patterns. Almost all batteries recover some capacity between uses, when used intermittently. When considering an alternate power supply for the Model 100, one should be provided whose rating exceeds the highest amount of current expected to be drawn. Thus, power supplies that provide 500 ma, 800 ma, or more should be perfectly compatible, as long as the voltage is in the 6 volt range, and the connector is properly polarized, so that the negative supply voltage is on the inner sleeve of the connector. (See Ralph Getsla's files POWER4.100 and POWER4.101 in DL4 for additional power information.) You need not be concerned that a supply is overrated; a device only draws the amount of current it needs. The "rating" is the amount of current the transformer or power pack can provide at maximum drain... it doesn't force the device to consume that amount of power.