The magnet is physically connected to a mechanical power switch, which opens as the magnet moves into the field. As voltage increases, so does the current, strengthening the magnetic field produced by the coil and pulling the core towards the field. The magnetic field produced by the current attracts a moving ferrous core held back under spring tension or gravitational pull. In electromechanical regulators, voltage regulation is easily accomplished by coiling the sensing wire to make an electromagnet. However, many regulators have over-current protection, so that they will entirely stop sourcing current (or limit the current in some way) if the output current is too high, and some regulators may also shut down if the input voltage is outside a given range (see also: crowbar circuits). If the output voltage is too low (perhaps due to input voltage reducing or load current increasing), the regulation element is commanded, up to a point, to produce a higher output voltage–by dropping less of the input voltage (for linear series regulators and buck switching regulators), or to draw input current for longer periods (boost-type switching regulators) if the output voltage is too high, the regulation element will normally be commanded to produce a lower voltage. (Stability is avoidance of oscillation, or ringing, during step changes.) There will also be a trade-off between stability and the speed of the response to changes. This forms a negative feedback control loop increasing the open-loop gain tends to increase regulation accuracy but reduce stability. Any difference is amplified and used to control the regulation element in such a way as to reduce the voltage error. Zener diode regulators make use of the zener diode's fixed reverse voltage, which can be quite large.įeedback voltage regulators operate by comparing the actual output voltage to some fixed reference voltage. When higher voltage output is needed, a zener diode or series of zener diodes may be employed. Since the forward voltage of a diode is small, this kind of voltage regulator is only suitable for When precise voltage control and efficiency are not important, this design may be fine. Due to the logarithmic shape of diode V-I curves, the voltage across the diode changes only slightly due to changes in current drawn or changes in the input. Block scheme for voltage regulator in an electronic circuitĪ simple voltage/current regulator can be made from a resistor in series with a diode (or series of diodes).
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