Search results
Results from the WOW.Com Content Network
The current and voltage across the thermistor depend on the particular circuit configuration. As a simple example, if the voltage across the thermistor is held fixed, then by Ohm's law we have = /, and the equilibrium equation can be solved for the ambient temperature as a function of the measured resistance of the thermistor:
The Steinhart–Hart equation is a model relating the varying electrical resistance of a semiconductor to its varying temperatures.The equation is = + + (), where is the temperature (in kelvins),
For example, if 120 V AC RMS is applied to a resistive heating element it would heat up by exactly the same amount as if 120 V DC were applied. This principle was exploited in early thermal converters. The AC signal would be applied to a small heating element that was matched with a thermistor, which could be used in a DC measuring circuit.
Function ¯ is expanded in terms of cosine functions for the and variables and in terms of hyperbolic cosines and sines for variable. Next, by applying adiabatic boundary conditions at the lateral walls and fix temperature at the bottom (heat sink temperature), thermal impedance matrix equation is derived:
For example, a PTC heating element with a sharp change in resistance at a particular temperature can be fitted with a constant voltage source and a variable-speed fan. With the fan at a low setting, the heating element draws only a small amount of current, resulting in a low heat output.
Example Consider a component such as a silicon transistor that is bolted to the metal frame of a piece of equipment. The transistor's manufacturer will specify parameters in the datasheet called the absolute thermal resistance from junction to case (symbol: R θ J C {\displaystyle R_{\theta {\rm {JC}}}} ), and the maximum allowable temperature ...
The new CFPB regulation would require large banks and credit unions to either charge just $5 for overdrafts or, alternatively, pick an amount no higher than the cost of offering overdraft protection.
Such relationship may take the form of a graph, where numerical values of a circuit variable are plotted versus frequency or component value (the most common example would be a plot of the magnitude of a transfer function vs. frequency). Symbolic circuit analysis is concerned with obtaining those relationships in symbolic form, i.e., in the ...