Light Meter Circuit


Posted on Jul 26, 2012

The outputs from the comparators will swing, in sequence, from high to low as the input voltage rises above the reference voltage applied to each comparator. The output LEDs will then switch on in sequence as the voltage rises. The inverting inputs of the comparators are connected in common to the collector of photo-transistor Ql. When Ql is illuminated, its collec-tor-emitter junction conducts, thereby placing all the inverting inputs within a few millivolts of ground. For most settings of Rl, each of the four reference voltages exceeds the value.


Light Meter Circuit
Click here to download the full size of the above Circuit.

Therefore, when Ql is illuminated, the output from each comparator is high and its respective indicator LED is off.




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

1 button ON / OFF Switch with 555
Multi-color LED driver
Logic probe yields three discrete states
LC feedback Oscillator
FAN302HL 5 volt switching power supply circuit design electronic project
lf286 Linux USB LCD display with watchdog and buttons
Electron Collection and Emission Using a Flyback Transformer



Top