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LED Brightness Control Circuits

2014-12-06 06:12  
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display/pngChange the  LED  brightness in three ways: using pulse width modulation; changing the current; changing the voltage. The first use pulse width modulation to control the brightness. That is maintained at a relatively high constant current value, and then by changing the percentage of time that different brightness LED to change its brightness. Second by changing the current flowing through the LED to vary the brightness of the. There are several pulse-width modulator circuit scene. Optical element isolation analog circuits using the pulse frequency modulation and can be used to improve the brightnes control. In the display circuit pro - 150 controller data is fed continuously into a shift register is fed from airborne 5 v power supply. LED display segment is a common traditional way of driving two parts anode 7-segment display is achieved by using a resistor in each cathode control the LED current. 16 segments = 16 resistors. A resistor array! Straightforward. So we dropped the circuit a 5 v to a lower voltage, the voltage in parallel to meet all the LED anodes. In fact, we did not use but a Darlington transistor NPN type. Works well but free Darlington display can be foreseen. The third change the voltage to change the brightness. led diode, so the current / voltage diagram is logarithmic. Therefore, a small voltage changes caused by a high brightness.



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