The Influence of Heat Pump on the Temperature!

Diode Power Dissipation - The power dissipation in a diode is simply calculated as the device terminal voltage multiplied by the current level.

Device manufacturers specify a maximum power dissipation for each type of diode. If the specified level is exceeded, the device will overheat and it may short-circuit or open-circuit.

The maximum power that may be dissipated in a diode (or any other electronic device) is normally specified for an ambient temperature of 25°C, or sometimes for a 25°C case temperature. When the Temperature Effect on Semiconductor Diode exceeds the specified level, the device maximum power dissipation must be derated.

Figure 2-16 shows the type of power-versus-temperature graph provided on some device data sheets. The maximum power dissipation for any given Temperature Effect on Semiconductor Diode can simply be read from the graph. Then, the maximum level of forward current is calculated from Eq. 2-4. Instead of a power-versus-temperature graph, the rectifier diode data has a current-versus-­temperature graph. This allows the maximum forward current at a desired temperature to be determined directly.

As an alternative to a power or current graph, a derating factor is sometimes listed on a device data sheet. As illustrated in Fig. 2-16, the derating factor defines the slope of the power-versus­-temperature graph. It can be used to draw the graph, or employed directly without reference to the graph. The equation for the new maximum power dissipation when the temperature changes involves the specified power at the specified temperature (P at T ), the temperature change (ΔT), and the derating factor.

There are circumstances in which it is important to know the precise level of a diode forward voltage drop. In these cases, the graphical analysis techniques discussed already may be appropriate. However, in Fig. 2-17, the voltage drop across a forward-biased pn-junction changes with Temperature Effect on Semiconductor Diode by approximately -1.8 mV/°C for a silicon device, and by -2.02 mV/°C for germanium. A diode V at any temperature can be calculated from a knowledge of V at the starting temperature (V at T ), the temperature change (ΔT), and the voltage/temperature coefficient (ΔV /°C).

Equation 2-2 for calculating the dynamic resistance of a forward biased diode is correct only for 25°C junction temperatures. For higher or lower temperatures, the equation must be modified to,

where T is the junction temperature in degrees Celsius.

Why have all global temperature reconstructions resulted in the 'hockey stick' shape?

Do you know where the devices being used for these recording are placed. There's one sitting directly under the exaust for an air condition unit, yeah, I am sure it's getting an accurate reading. You can make anything scienctific say what ever you want, so long as you tweek it a little.

How much does a drop in temperature affect focus?

From my reading, the amount materials within a "handheld" lens expand / contract over, for example, 15C is so minimal it's not worth thinking about.However this really becomes an issue on large telescopes, both refracting and reflecting (even more so).Why?As a (rough) example, let's imagine a large reflecting telescope which has a body length of 3m, and is constructed from tubular aluminium. Pure aluminium pure has a linear thermal expansion rate of 0.0000222m/m/K, which means it gets longer / shorter by 0.0222mm per degree Kelvin (or C) per meter of its length. Therefore the telescope would shorten by 0.0222mm 3m 15C = 0.999mm as the temperature drops 15C. This coupled with the magnification at the secondary mirror leads to a dramatic focus shift

Car temperature guage keeps leaning to hot but doesnt overheat?

Might be some air in the system if it is not the thermostat. Why not get the coolant changed? Get it from the dealer. Do not use aftermarket crap like Prestone All Makes All Models (it is not ).

How do i lower my fish tank temperature?

U can buy a fan but make sure you buy the right fan..I mean, some are big fan and some are small fan! If you want to save money, dont want to buy anything but wants the water temperature to become low, you can take a few bottle and put some water inside and let it freeze inside your refrigerator and soon, u take it out and put it inside your tank...This is what my LFS teach me...Hope it help :)