What happens when an electrolytic cap is reversed: Also, the anodic oxide dielectric is polar, and so are the electrolytic capacitors (in contrast with the classical, electrostatic capacitors), that is the capacitors must be connected with the correct polarity as marked. """Connecting with reverse voltage injects hydrogen ions through the oxide readily, causing high electrical conduction, heating and reduction of the anodic oxide film."""" = explosion. Non-polar (or bi-polar) devices can be made by using two anodes instead of an anode and a cathode, or one could connect the positives or negatives of two identical device together, then the other two terminals would form a non-polar device. What makes an electrolytic cap: Electrolytic capacitors: Electrolytic capacitors are capacitors in which one or both of the "plates" is a non-metallic conductive substance, an electrolyte. Electrolytes have lower conductivity than metals, so are only used in capacitors when metallic plate is not practical, such as when the dielectric surface is fragile or rough in shape or when ionic current is required to maintain the dielectric integrity. The dielectric material of electrolytic capacitors is produced from the anode metal itself in what is known as the forming (or anodizing process. During this process, current flows from the anode metal - which must be a valve metal such as aluminum, niobium, tantalum, titanium, or silicon - through a conductive bath of a special forming electrolyte to the bath cathode Extracted from: http://electrochem.cwru.edu/ed/encycl/art-c04-electr-cap.htm Ramon -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Cicchiani, Arlene M. Sent: Tuesday, October 24, 2006 2:37 PM To: [log in to unmask] Subject: [TN] capacitor polarity or not As a trainer, how would I explain to a manufacturer, in simple terms, the reason some capacitors have polarity, and some do not. --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------