Leds indicate the amplitude of the current circuit design

Figure in LED luminous intensity is proportional to the load current, the circuit is designed to provide a very compact circuit to replace some astronomy equipments of meter on the 12 v power supply cord. This device contains work condition of the invisible small power heating element ( Dew components) 。 However, when the heater, LED can emit visible light, thus explicitly indicates they have been connected and working.

circuit analysis is very simple. 22 the resistance at the ends of the voltage is the same as the voltage at the ends of the RSENSE. Through the 22 euro resistance current through the LED current with the same. Therefore, for the values of the parameters given in the figure, the LED current is equal to the load current of 0. 05/22. When the load current ma changes from 200 to 6. 6 a, LED from the weak light changes to full brightness ( Limited by resistance), 680 。

if you need, you can join another LED to compare with fixed resistors. In addition, can also build the circuit through the different instances of the histogram display results, in these circuits example, use different resistance instead of 22 European resistance, RSENSE is unchanged.

can achieve positive voltage operational amplifier must have amplitude rail input and output, and can withstand the slightly more than 12 v power supply voltage. TI company's choice of TLV2731 is to meet these requirements.

when load current is 200 ma, LED a faint light; When the load current growth to 6. 6 a, the LED light emitted by the light.