I don't think anyone would design a camera or other piece of equipment to deliberately short out the power source. As long as you meet, and don't exceed, the required operating voltage for a piece of equipment, it's internal resistance will limit current flow to that amount determined by Ohm's law. I've run 12-volt/200ma walkie talkies on lead acid car batteries meant to provide 200+ amperes of current to start large engines, with no problems unless I exceeded the duty cycle of the walkie talkie. You can exceed the duty cycle with small batteries as well as with big ones. If you do, it will fail in either case, though the failure may release more smoke with the big batteries. :-)
For the guys that don't know, duty cycle refers to the amount of time that the device can be on before you must shut it down to give it a chance to cool down. Normally the duty cycle for a transmitter will be given as a percentage, with 50% being pretty common. It was also given in terms of transmitting time versus off time. 50% meant that if you transmitted for the given max transmit time, you had to let it rest for the same amount of time before the next transmission. Camera drive motors have some sort of duty cycle too. The good ones are usually enough so you can fire off a 36-exposure roll of film and the time spent unloading the film and reloading the next will be enough to satisfy the duty cycle of the drive motor. Len --- -----Original Message----- From: Kent Gittings [mailto:[EMAIL PROTECTED]] Sent: Tuesday, December 18, 2001 8:00 AM To: [EMAIL PROTECTED] Subject: RE: Rechargeable (2CR5) for PZ-1p The only other case I can think of is a power design that lacks any kind of current limiting circuitry. In such a design the power source then would have to be based on something that had a maximum output that couldn't exceed a particular value due to inherent design. Something like the type or chemical process of the battery. In that case switching to an alternate source of power that had no current limiting of its own (by design or the technology) could effectively burn it out if the true ohm value of the load was such that it produced a much higher current if the power course could flow that much current. Kent Gittings Somebody > mentioned that the "hardness" (high current output under big drain) of > NiCd or big NiMH might damage the motor or something, is this really > true? Although I don't have this camera, I have made batterypacks for > almost everything photo-electric I have (mostly using old notebook > batteries, a friend tested them and selected the best for me, > suprising how they hold), so it's a curiosity-question. > > Good light, > Frantisek - - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
