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The output impedance is a measure of the source's propensity to drop in voltage when the load draws current, the source network being the portion of the network that transmits and the load network being the portion of the network that consumes. Because of this the output impedance is sometimes referred to as the source impedance or internal ...
The red curve shows the power in the load, normalized relative to its maximum possible. The dark blue curve shows the efficiency η. The efficiency η is the ratio of the power dissipated by the load resistance R L to the total power dissipated by the circuit (which includes the voltage source's resistance of R S as well as R L):
If energy output and input are expressed in the same units, efficiency is a dimensionless number. [1] Where it is not customary or convenient to represent input and output energy in the same units, efficiency-like quantities have units associated with them. For example, the heat rate of a fossil fuel power plant may be expressed in BTU per ...
For devices with very high output impedances, such as with a guitar pickup or a high-Z mic, a DI box can help with impedance bridging by converting the high output impedances to a lower impedance so as to not require the receiving device to have outrageously high input impedance (which would suffer drawbacks such as increased noise in long ...
Efficiency is a measure of how much of the power source is usefully applied to the amplifier's output. Class A amplifiers are very inefficient, in the range of 10–20% with a max efficiency of 25% for direct coupling of the output. Inductive coupling of the output can raise their efficiency to a maximum of 50%.
In mechanical engineering, mechanical efficiency is a dimensionless ratio that measures the efficiency of a mechanism or machine in transforming the power input to the device to power output. A machine is a mechanical linkage in which force is applied at one point, and the force does work moving a load at another point.
A Class B push–pull output driver using a pair of complementary PNP and NPN bipolar junction transistors configured as emitter followers. A push–pull amplifier is a type of electronic circuit that uses a pair of active devices that alternately supply current to, or absorb current from, a connected load. This kind of amplifier can enhance ...
One way to use total system power to get a more accurate estimate of power is to consider the amplifier class which would give an educated guess of the power output by considering the efficiency of the class. For example, class AB amplifiers can vary widely from 25% to 75% efficiency while Class D amps are much higher at 80% to 95%.