Timed Relay, 12 seconds to 90 minutes
Parts List:
R1,R3 = 220                            IC1 = 555, timer/oscillator
   R2 = 470                             D1 = 1N4001, general purpose diode
   R4 = 27K                            Led = Red, high brightness
   P1 = 7.5M, potentiometer             S1 = Push switch, momentary off
   C1 = 220uF/25V, electrolytic         S2 = Push switch, momentary on
   C2 = 470uF/16V, electrolytic        Ry1 = 6-9V
   C3 = 0.001uF (1nF),ceramic
   C4 = 10pF to 0.001uF, ceramic
Notes:
C4 may not be needed. Add only if relay 'chatters'. Value can be up to 0.001uF.
Led will be lit when relay is "on".


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Copyright © 2005 - Tony van Roon