Timed Relay, 12 seconds to 90 minutes
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
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