Interfacing Relay To Microcontroller


Posted on Dec 16, 2012

Relays are devices which allow low power circuits to switch a relatively high Current/Voltage ON/OFF. For a relay to operate a suitable pull-in & holding current should be passed through its coil. Generally relay coils are designed to operate from a particular voltage often its 5V or 12V. The function of relay driver circuit is to provide the necessary current (typically 25 to 70ma) to energize the relay coil.


Interfacing Relay To Microcontroller
Click here to download the full size of the above Circuit.

Figure 1 shows the basic relay driver circuit. As you can see an NPN transistor BC547 is being used to control the relay. The transistor is driven into saturation (turned ON) when a LOGIC 1 is written on the PORT PIN thus turning ON the relay. The relay




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

Quick Multiconductor Cable Tester
L497 HALL EFFECT PICKUP IGNITION CONTROLLER
MAX8844 lithium ion charger electronic circuit design
FM Antenna Amplifier Circuit
Henry Radio 5K Classic Blower Modifications
Long-range FM radio transmitter circuit
Flasher Circuits
Switchless NiCd-NiMH Battery Charger
Extended delta decompression starter control circuit



Top