Chris, my guess is the resistor is to help discharge the capacitors in the unit. It is probably there so the unit will reset faster when you pull the batteries. It is usually good to have capacitors across batteries, you just want to make sure they are low leakage. If they are not low leakage, they will drain the batteries fairly fast.
Jim Jim Bacher, Senior Engineer Paxar - Monarch email:[email protected] voice:1-937-865-2020 fax:1-937-865-2048 ____________________Reply Separator____________________ Subject: Battery Safety Author: "Maxwell; Chris" <[email protected]> List-Post: [email protected] Date: 9/25/00 11:30 AM All, We have inherited a design from a company which we purchased. The product is a handheld and can be operated from a pair of Alkaline batteries. Inside the unit, there is a 91 KOhm resistor across the + and - terminals of the batteries. Since the people who designed the instrument are long gone, some of my collegues have asked me if this resistor could be a safety feature. I can't think of any way this resistor would help the safety of the instrument. I did read through the safety test report; and I found no reference to this resistor being required. All it does is provide a constant drain on the battery (reducing battery life). It has been suggested to me that some designers put resistors across batteries to reduce the electrical noise in a product. To me a capacitor would be better for this because it wouldn't drain the battery while it was filtering. Even so, isn't a battery the ultimate capacitor? I'm just drawing a blank why anyone would do this. I'd love to recommend that we pull this resistor out because it's a pain to solder and it affects battery life. However, I don't want to sacrifice the safety of the product. Anybody want to take a guess at this one? Thanks. Chris Maxwell, Design Engineer GN Nettest Optical Division 6 Rhoads Drive, Building 4 Utica, NY 13502 PH: 315-797-4449 FAX: 315-797-8024 EMAIL: [email protected] ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: [email protected] Michael Garretson: [email protected] For policy questions, send mail to: Richard Nute: [email protected]
