with the temperature drop, down a set of equal portions of each temperature measurement and a heat sink temperature forward voltage drop has been measured at 25 , when the completion of the data sets of measurements into computer software database, the software generates a vf-tj curve. this method is the measurement temperature decreases, the measurement is feasible, but because the test room ambient temperature is set value (usually 25 ), and silicone oil tank oil temperature is decreased from high to low , and this caused the oil tank when the silicone oil is high, because the laboratory environment with large temperature difference between the temperature.
vinyl signs according to equation 2.2 we can see, and d is proportional to the duty cycle d can be changed as long as the change in primary current size, it can change the size of the output power. 2.2 the advantages and disadvantages of theory, this topology is simple, low cost, but careful analysis will find that this approach has many drawbacks. the first is difficult to conol, often large deviations, together with open-loop conol, precision is difficult to ensure, in the volume, use the same power output duty cycle will result in significant bias, is directly reflected in the led lights on the great brightness bias, it is difficult to ensure consistency.
led scrolling signuntil the rated current value. rated power so it can be compatible with the following led lights. the problem for the no-load losses can be used to detect whether a load access mcu, led access when not detected, you can turn off the circuit after the class buck, reducing the load loss. finally, the scr compatibility issues. constant power conol scheme, using pure hardware mode to stabilize the scr turns on, the adaptability of dimmer or limited. constant current conol in the mcu program, in addition to stable hardware circuit, as well as software to scr chopper waveform after the identification processing.
lawn signs
