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How do I choose a flyback diode?
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.
Can you oversize a diode?
In almost all cases, no. Most diodes will be at around 0.7 to 1 volt of forward voltage, (almost) regardless of current and breakdown voltage. However, higher voltage ratings often come with a higher forward voltage drop and (at equal current into the load) higher power losses.
What does a flyback diode do?
A flyback diode is a diode connected across an inductor used to eliminate flyback, which is the sudden voltage spike seen across an inductive load when its supply current is suddenly reduced or interrupted. It is used in circuits in which inductive loads are controlled by switches, and in switching power supplies…
Which kind of diode to handle flyback voltage?
The freewheeling diode allows current to pass with minimal resistance and prevents flyback voltage from building up, hence the name flyback diode. Tiny flyback diodes prevent huge flyback voltage from damaging your components. Flyback Diode Wiring for Relay Noise Suppression. The placement of a flyback protection diode is rather simple; it should be placed directly across the relay’s coil. A schematic for a freewheeling diode circuit in a relay is shown below.
Does a fan need a flyback diode?
There shouldn’t be any need for a flyback diode across this fan, unless there is some significant series inductance eg a EMI filter inside the motor. But, when in doubt, add a flyback diode. It’s cheaper to add one unnecessary diode than frying your circuit because you did need one.
What is a free wheel diode?
A free wheeling or flyback diode is used to prevent damage to circuits typically with any load that has an inductor and any switching potential. An inductor can’t change current immediately.