Do I need a diode on my relay?
With a transistor output driving a relay, a freewheeling diode is absolutely necessary, because the voltage spike will destroy the transistor. When using a switch to turn on/off a relay, omitting the diode will work, but your switch will be happier when you use a diode (one individual diode for each relay).
Why do I need flyback diodes?
Applications. Flyback diodes are commonly used when inductive loads are switched off by semiconductor devices: in relay drivers, H-bridge motor drivers, and so on. When the inductive load is a relay, the flyback diode can noticeably delay the release of the relay by keeping the coil current flowing longer.
What is feedback diode?
For RL loads, load current will not be in phase with load voltage and the diodes connected in anti parallel will allow the current to flow when the main thyristors are turned off. These diodes are called feedback diodes.
How to choose a fly back diode for a relay?
Here R is the resistance of the fly-back diode in conduction, I is the current flowing through the fly-back diode and L is the inductance supplying the current. If we solve for the power, something very interesting happens…
How does a flyback diode keep the electrons moving?
The flyback diode keeps the electrons moving by shunting them back into the relay coil. Because the electrons keep moving, the collapse of the magnetic field is slowed down, and the generated voltage will be much lower. Switch contacts and semiconductor junctions can easily handle these lower voltages.
What should the reverse voltage of a relay be?
In your relay, the coil current is shown as 79.4 mA. Specify a diode for at least 79.4 mA current. In your case, a 1N4001 current rating far exceeds the requirement. The diode reverse voltage rating should be at least the voltage applied to the relay coil. Normally a designer puts in plenty of reserve in the reverse rating.
What makes a flyback diode a snubber circuit?
Moving electrons in a coil of wire produce magnetism and it’s the magnetism that pulls the armature. A flyback diode is actually a type of snubber circuit. A snubber circuit protects the rest of the circuitry from a magnetic coil. A snubber circuit also reduces the RF interference being transmitted from the circuit.