Why is a diode connected in a series with resistors?
It is possible that the diode series resistor is used as a current limiting resistor to avoid destroying the diode because the diodes are current sensitive devices, in addition to their very limited current carrying capacity.
The main purpose of the diode is to send the current in one direction. it will not allow the current flowing in the opposite direction.
it’s like a one-way door where you can enter and can not go out the same door.
A diode connected in series makes it possible to control the flow of current in the resistances, whereas a diode connected in parallel deviates the flow of current of the resistances towards the diode, according to whether the diode is lit or not.
Generally, a diode connected in series is used in the rectifying circuits, while a diode connected in parallel is used in the mower or blocking circuits.
a diode is connected in series with a resistor because a diode acts essentially as a direct bias while being open and inverted, when a diode is forward biased, its resistance is very low and produces a very high circuit current.
if a resistor is not added in series, the total resistance of the circuit is increased and the current reduced. unless the diode and source are specifically designed to operate at very high circuit currents with just one diode connected by itself, that’s a bad idea.
Rectified diode AC voltage in direct current. the continuous output must be used for purposes or for a load. the output waveform is a series of half waves on one side of the reference zero volt.
This needs to be turned into smooth DC before it can be used easily. this is done by a filter circuit composed of circuits lr or rc. therefore, you always find a resistor after the diode usually with a capacitor and sometimes with an additional inductor.
The filter circuit converts the output of the rectifier into an acceptable smooth continuous current, which is then used for subsequent parts of the circuit.
A light emitting diode is intended only to emit light whenever current passes through it. this requires that the current is also limited within the LED limits. in this case, a series resistor serves as a current limiter.
Similarly, a zener diode needs a current limiter because it maintains a constant voltage. the current must be limited in the zener branch by a separate resistor in series.
A continuous ammeter converted to AC power, as well as many measurement applications, requires a diode with a series resistor to adjust the fsd of the instrument.
There will also be other examples in which the series resistance becomes necessary as a current limiter.