Category: Main page » Electronics for home living

Time Delay Relay-2

By jawaharlal@excite.com

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.

Schematic


Schematic for Time Delay Relay

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.


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