Contents
Why is a transistor used to control the relay coil?
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.
What is active high and active low?
Simply put, this just describes how the pin is activated. If it’s an active-low pin, you must “pull” that pin LOW by connecting it to ground. For an active high pin, you connect it to your HIGH voltage (usually 3.3V/5V). For example, let’s say you have a shift register that has a chip enable pin, CE.
Should I use a relay or transistor?
Generally, if you are switching DC motors, solenoids, or other high-current DC devices which create motion, it’s better to use a switching transistor than a relay. The ideal way to control a motor is with an H-bridge, which is an array of transistors that lets you control not only speed but also direction.
Can a transistor be used as a relay switch?
Transistor as a Switch for Relay Transistors are capable of driving small relays without any problems. Usually, an NPN transistor in a common emitter configuration used as a switch drives the relay. Here is a simple circuit that uses a bipolar junction transistor (BJT) to drive a small 5 V relay coil.
When to use active low or active high relay?
In case of active low, the relay will activate when we apply an active low signal to the signal pin. On the contrary, in the case of an active high, the relay will activate when we apply an active high signal to the signal pin.
What are the different types of relay modules?
There are two types of relay modules according to a type of control signal used for relay activation. One comes with a NPN transistor and the other with a PNP transistor. If a NPN Transistor is used, the relay will become active when we apply an active high signal on the control pin.
What do you need to control a 5V relay module?
Similarly for PNP type relay modules, an active low signal, activates the relay and an active high signal deactivates the relay. To control a 5V single-channel relay module with any microcontroller, we need to use a GPIO pin as a digital output pin. Digital output pin provides an active low and active high signal to control pin of relay module.