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timed relay

Printed From: the12volt.com
Forum Name: Relays
Forum Discription: Relay Diagrams, SPDT Relays, SPST Relays, DPDT Relays, Latching Relays, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=13030
Printed Date: February 06, 2026 at 9:12 PM


Topic: timed relay

Posted By: dragonracing
Subject: timed relay
Date Posted: May 01, 2003 at 2:25 PM

I need to power something for 2 seconds after the power is cut.  I need to know what size capacitor and resitor to use.  And where could i get a capacitor that size



Replies:

Posted By: Thinkster
Date Posted: May 02, 2003 at 3:55 AM
Generaly in RC circuits, Time=(R*C). Usually capacitors are in uF (so in calculating, use Exponent -6) and resistors are usally in K (to the Exponent 3) So in my calculations, a 100uF cap and a 20K resistor should be about 2 seconds. You can probably get caps & resistors at a local electronic store or possibly Rat Shack. For online ordering, try DigiKey or Mouser.




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