Bil, Some good information pertaining to your question here: http://www.liean-gimn.com/products/7.htm Hope this helps. David Lessard Mr_fixit@xxxxxxxxxxxx Alexandria, Ontario, Canada -----Original Message----- From: techassist-bounce@xxxxxxxxxxxxx [mailto:techassist-bounce@xxxxxxxxxxxxx] On Behalf Of Bil Green Sent: Sunday, April 24, 2005 8:22 AM To: .TECHASSIST @ freelists . org Subject: [TechAssist] Voltage Rating of Resistors If anyone is very familiar with the voltage ratings of carbon film resistors, I could use some help. I would like to know if the Max. Overload Voltage of carbon film resistors (this is 2 x times the working voltage) would apply in this instance: I would like to use three 1.8k, 1/2W resistors* in series with a 1700VDC supply to charge a 0.5uF capacitor. It will fully charge in approx. one second. * 1/2W carbon film resistors are rated at 350V (working voltage) I realize that this is not exactly a surge condition, however the voltage exceeding the rating of these resistors would only exist for about 1/2 second (and would be below the Max. Overload Voltage of the 3 resistors wired in series). This is to be used in a magnetic pulse generator in which the capacitor discharges into a coil once per second (one second to fully charge and a very small fraction of one second to discharge). This instrument would only be used for a few minutes per day, and must be reliable. I will be ordering some 1W resistors (500V rating), but have a couple units that need to be shipped out on Monday. From what I've read, it's common for engineers to not consider the voltage rating of resistors when designing circuits, so I don't feel negligent, since I am doing the best I can at this time. Bil PC 1000 Mammoth Lakes, CA 760-924-1000 M-Pulse 5000 magnetic pulse generator http://www.heal-me.com.au/m-pulse5000.htm ------------------------------------------------------------------------ ----- This Email List is Public. Remove: http://www.tech-assist.org/remove.htm Lost Password: http://www.tech-assist.org and select "Login Problems?". Appliance Repair List: http://www.tech-assist.org/secure/tip/chatjoin.htm#app Email Archives: //www.freelists.org/archives/techassist/ ----------------------------------------------------------------------------- This Email List is Public. Remove: http://www.tech-assist.org/remove.htm Lost Password: http://www.tech-assist.org and select "Login Problems?". Appliance Repair List: http://www.tech-assist.org/secure/tip/chatjoin.htm#app Email Archives: //www.freelists.org/archives/techassist/