Thursday, May 15, 2014

4 Channel relay board using L293D

         Many time it requires controlling relays to automate different things in projects.But thing is generally Relays are driven by either high voltage and requires high current but most of the embedded systems works at lower voltage and the constrain is they cant provide high current.

          Their comes the requirement of a circuit which can drive relays taking input from the micro-controller board and also provide the required current to drive relays.Transistors can be used as H-Bridge driver but it makes little complexity so relay drivers IC can be used and are also cheaper.Here i have given design of a 4 Channel Relay driver circuit.Two circuits are designed using ULN2803 or L293D.

Using L293D:


Using ULN2803 :