How do you connect a transistor to a relay?
As well as the standard Common Emitter configuration for a relay switch circuit, the relay coil can also be connected to the Emitter terminal of the transistor to form an Emitter Follower circuit. The input signal is connected directly to the Base, while the output is taken from the Emitter load as shown.
What is difference between transistor and relay output?
Transistor Output is a solid state configuration which can work at a fast rate. Relays are more electromechanical so they are slow. If you need to drive more current with the transistor output, you can always use a solid state relay.
What does a transistor do in a relay?
A transistor is an electronic device that can work as a switch. It allows control of a large current by a smaller current as does a relay.
Is a relay coil an output?
In electromechanical relays, the coil accomplishes this function. A relays Output Circuit is the portion of the relay that switches on the load and performs the same function as the mechanical contacts of electromechanical relays. Solid-state relays, however, normally have only one output contact.
Should I use a relay or a transistor?
A relay can be used with AC or DC power over a very broad range of power levels. A transistor is generally meant to be used with DC power or digital signals, but they can be used with AC signals as well.
How do you hook up a transistor?
To connect the transistor as a switch in a circuit, we connect the output of the device that will switch on the transistor to the base of the transistor. The emitter will connect to ground of the circuit. And the collector will connect to the load that the transistor will turn on and the supply voltage of the circuit.
How does a transistor output work?
The transistor works as an open switch. As a consequence, the output voltage is equal to the voltage source Vcc. Injecting enough current into the base, a current flows from Vcc to the ground and the output voltage is the same as the ground, i.e., the transistor works as a closed switch.
What is output transistor?
Output transistors are added to provide extra current to drive a speaker. Large output transistors only have a small HFE current gain, therefore driver transistors are placed in front of the output transistors to increase to total current gain to approx 200.
Is relay and transistor the same?
Is a transistor faster than a relay?
Transistors: Speed and Simplicity Here are eight specific characteristics of transistors, as opposed to relays: – They’re much faster than relays.
What is the voltage across the relay coil of a transistor?
For example input from the pulse output digital pulse of 12 volts to drive to the transistor. Therefore, we will have voltage across the relay coil about 12V-0.7V = 11.3V, etc.
How to calculate the current of a relay coil?
So if we know voltage of relay will also calculate the current of coil. such as voltage of relay is 12 volts. The resistance of relay coil 120 ohms will can calculate current flowing through the relay coil is 12 divided by 120 equals 0.1 A or 100 mA etc.
Can a transistor be used as a switch for relay?
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.
Why is the diode connected across the relay coil?
The diode connected across the relay coil though is no way related with the above calculation, it still cannot be ignored. The diode makes sure that the reverse EMF generated from the relay coil is shorted through it, and not dumped into the transistor.