A time delay relay is a relay that stays on for a certain amount of time once activated. This time delay relay is made up of a simple adjustable timer circuit which controls the actual relay. The time is adjustable from 0 to about 20 seconds with the parts specified. The current capacity of the circuit is only limited by what kind of relay you decide to use.
Schematic-
Parts List-
R1 - 1 - 1 Meg Pot
R2 - 1 - 10 K 1/4 Watt Resistor
C1 - 1 - 10uf 25V Electrolytic Capacitor
C2 - 1 - 0.01uf Ceramic Disc Capacitor
D1,D2 - 2 - 1N914 Diodes
U1 - 1 - 555 Timer IC
RELAY - 1 - 9V Relay
S1 - 1 - 1A 120V SPST Switch
MISC - 1 - Board, Wire, Socket For U1
Notes-
1. R1 adjusts the on time.
2. You can use a different capacitor for C1 to change the maximum on time.
3. S1 is used to activate the timing cycle. S1 can be replaced by a NPN transistor so that the circuit may be triggered by a computer, other circuit, etc.
Schematic-
Parts List-
R1 - 1 - 1 Meg Pot
R2 - 1 - 10 K 1/4 Watt Resistor
C1 - 1 - 10uf 25V Electrolytic Capacitor
C2 - 1 - 0.01uf Ceramic Disc Capacitor
D1,D2 - 2 - 1N914 Diodes
U1 - 1 - 555 Timer IC
RELAY - 1 - 9V Relay
S1 - 1 - 1A 120V SPST Switch
MISC - 1 - Board, Wire, Socket For U1
Notes-
1. R1 adjusts the on time.
2. You can use a different capacitor for C1 to change the maximum on time.
3. S1 is used to activate the timing cycle. S1 can be replaced by a NPN transistor so that the circuit may be triggered by a computer, other circuit, etc.
