How a 5V relay works?
HOW THE 5V RELAY WORKS. The SRD-05VDC-SL-C relay has three high voltage terminals (NC, C, and NO) which connect to the device you want to control. The other side has three low voltage pins (Ground, Vcc, and Signal) which connect to the Arduino. Inside the relay is a 120-240V switch that’s connected to an electromagnet.
Why use transistor with relay?
A transistor in between will allow a 5V signal from the Arduino to switch a 12V signal via the transistor to the relay – thus turning it on. 2) The transistor provides protection. In the event of a back emf voltage spike or some other undesired event only your transistor will be blown, instead of the entire Arduino.
How to operate a relay with transistor?
A typical relay switch circuit has the coil driven by a NPN transistor switch, TR1 as shown depending on the input voltage level. When the Base voltage of the transistor is zero (or negative), the transistor is cut-off and acts as an open switch.
What kind of transistor is needed for 5V relay?
Transistor can be 2n2222, 2n3904, etc. You can drive the relay primary from the 5 Volt source, while switching it using the 3.3 Volt signal, by using an N-MOSFET as a switch: The simulation link is here. The MOSFET you need should have a logic-level input, or a Vgs (th) of well below 3.3 Volts.
How is a relay interfaced with a microcontroller?
A relay can be easily interfaced with microcontroller using a transistor as shown below. Transistor is wired as a switch which carries the current required for operation of the relay. When the pin RB7 of the PIC microcontroller goes high, the transistor BC547 turns On and current flows through the relay.
Can a 5 volt relay control two LEDs?
This Instructable demonstrates using a 5 volt mechanical relay as a switch to control two LEDs. There are two different wiring configurations demonstrated. The first wiring toggles two LEDs, one “on” and one “off”. The second wiring switches the two LEDs both “on” or both “off”.
What kind of current does a PIC microcontroller need?
The maximum current that a PIC Microcontroller can source or sink is 25mA while a relay needs about 50 – 100mA current. A relay is activated by energizing its coil. Microcontroller may stop working by the negative voltages produced in the relay due to its back emf.