Time Delay Relay II

Schematic

Parts

Part Total Qty. Description Substitutions C1 1 See Notes R1 1 See Notes D1 1 1N914 Diode U1 1 4011 CMOS NAND Gate IC K1 1 6V Relay S1 1 Normally Open Push Button Switch MISC 1 Board, Wire, Socket For U1

Notes

1. Email jawaharlal@excite.com with comments, questions, etc.
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.