When activated by pressing a button, this time delay relay will activate a load after a specified amount of time. This time is adjustable to whatever you want simply by changing the value of a resistor and/or capacitor. The current capacity of the circuit is only limited by what kind of relay you decide to use.
4011 CMOS NAND Gate IC
Normally Open Push Button Switch
Board, Wire, Socket For U1
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2. To calculate the time delay, use the equation R1 * C1 * 0.85=T, where R1 is the value of R1 in Ohms, C1 is the value of C1 in uF, and T is the time delay in seconds.
3. S1 may be replaced with an NPN transistor so the circuit can be triggered by a computer, other circuits, etc.
4. Most any 6V relay will work for K1. If you use a large relay, you my need to add a transistor to the output of the circuit in order to drive the larger load.
Source: Electronics Lab