Introduction to Bridge Circuits
– Bridge circuits are a topology of electrical circuitry.
– They consist of two parallel circuit branches bridged by a third branch.
– The bridge circuit was originally developed for laboratory measurement purposes.
– One of the bridging points is often adjustable.
– Bridge circuits find applications in instrumentation, filtering, and power conversion.
The Wheatstone Bridge
– The Wheatstone bridge is a well-known bridge circuit.
– It was invented by Samuel Hunter Christie and popularized by Charles Wheatstone.
– The Wheatstone bridge is used for measuring resistance.
– It consists of four resistors, two of known values, one unknown resistor, and one variable resistor.
– The ratio between the variable resistor and its neighbor enables the calculation of the unknown resistor.
Generalizations of the Wheatstone Bridge
– The Wheatstone bridge has been generalized to measure impedance in AC circuits.
– It can also measure resistance, inductance, capacitance, and dissipation factor separately.
– Variants of the Wheatstone bridge include the Wien bridge, Maxwell bridge, and Heaviside bridge.
– These variants are used to measure specific electrical properties.
– All variants compare the output of two potential dividers sharing a common source.
Bridge Circuits in Power Supply Design
– In power supply design, bridge circuits or bridge rectifiers are used.
– They convert electric current from an unknown or alternating polarity to a known polarity.
– Bridge rectifiers consist of diodes or similar devices.
– They rectify the current, converting it to a direct current.
– Bridge circuits in power supply design ensure a consistent and known polarity.
Bridge Circuits in Motor Control
– In some motor controllers, H-bridges are used.
– H-bridges control the direction in which the motor turns.
– They are widely used in robotics and automation systems.
– H-bridges consist of switches that control the flow of current through the motor.
– By controlling the switches, the direction of the motor can be changed. Source: https://en.wikipedia.org/wiki/Bridge_circuit
A bridge circuit is a topology of electrical circuitry in which two circuit branches (usually in parallel with each other) are "bridged" by a third branch connected between the first two branches at some intermediate point along them. The bridge was originally developed for laboratory measurement purposes and one of the intermediate bridging points is often adjustable when so used. Bridge circuits now find many applications, both linear and non-linear, including in instrumentation, filtering and power conversion.
The best-known bridge circuit, the Wheatstone bridge, was invented by Samuel Hunter Christie and popularized by Charles Wheatstone, and is used for measuring resistance. It is constructed from four resistors, two of known values R1 and R3 (see diagram), one whose resistance is to be determined Rx, and one which is variable and calibrated R2. Two opposite vertices are connected to a source of electric current, such as a battery, and a galvanometer is connected across the other two vertices. The variable resistor is adjusted until the galvanometer reads zero. It is then known that the ratio between the variable resistor and its neighbour R1 is equal to the ratio between the unknown resistor and its neighbour R3, which enables the value of the unknown resistor to be calculated.
The Wheatstone bridge has also been generalised to measure impedance in AC circuits, and to measure resistance, inductance, capacitance, and dissipation factor separately. Variants are known as the Wien bridge, Maxwell bridge, and Heaviside bridge (used to measure the effect of mutual inductance). All are based on the same principle, which is to compare the output of two potential dividers sharing a common source.
In power supply design, a bridge circuit or bridge rectifier is an arrangement of diodes or similar devices used to rectify an electric current, i.e. to convert it from an unknown or alternating polarity to a direct current of known polarity.
In some motor controllers, an H-bridge is used to control the direction the motor turns.
