For both the 82240A and 82240B, the manuals specify 9-12 V AC or DC; 500-1500 mA. Experimentally, either polarity works fine; I surmise that the external power goes through a bridge rectifier. The manual also says that you should have batteries installed even when using the AC adapter, as the printer may require supplemental battery power during heavy printing; my experience is that it works just fine without batteries, but it's no doubt best not to push your luck on this. The power connector is specified as 5-5.5 mm outside diameter, 2.1 mm inside diameter.
HP made two AC adapters for these printers. The earlier HP 82241A adapter is rated at 9V AC 13.5VA MAX; the later HP F1011A at 12V DC 0.75A. The 82241A uses a fixed input voltage and frequency (120 V 60 Hz for the U.S. option); the F1011A takes an input from 100-240V at 50-60 Hz and is much lighter, but runs warmer. I believe that both are available in various options to fit various styles of outlets.
The 82240A has only the "Roman 8" character set, and works with the 28 series calculators, and I expect a good many others. The 82240B has both the "Roman 8" character set and the "ECMA 94" character set. The ECMA 94 character set is used in the 48 series calculators, so if you want to print from a 48 series, the 82240B is better. That said, the 48 series provides for character remapping when printing via IR, so the more commonly used characters will still print ok on a 82240A. Of course, the 82240B is also fine for any calculator that prints to the 82240A. I don't know which character set is used in the 38G and so on.
The 48 series calculators, when printing via IR, start out each transmission to the printer (well, except from the CR command) with an escape sequence to switch the 82240B to the ECMA 94 character set. If an 82240A printer is being used, this escape sequence is simply ignored.
Regards,
James
Edited: 4 Oct 2003, 2:32 a.m.