Current Limiting Resistor Calculator for Leds
-
If you want to calculate Resistor, please visit Here!
Some good values to try:
As supply voltage:
For molex: 5, 7 and 12 volts
Batteries: 1.5 and 9 volts
...
7:49 PM
For this Section, Please read Infrared Light Photo-Detector Circuit First!
Basic Phototransistor Detector
In this circuit the light falling on the phototransistor will be from an Infrared Light Emitting Diode (IrLED) but otherwise it is the same as the phototransistor circuit shown above.
When the light falling on the phototransistor (Q1) is blocked, its conductance will decrease and the voltage across Q1 will rise. When the voltage rises above 1/2 of the supply voltage the output of the comparator will turn ON and the LED will be lit.
Basic Phototransistor Detector
In this circuit the light falling on the phototransistor will be from an Infrared Light Emitting Diode (IrLED) but otherwise it is the same as the phototransistor circuit shown above.
When the light falling on the phototransistor (Q1) is blocked, its conductance will decrease and the voltage across Q1 will rise. When the voltage rises above 1/2 of the supply voltage the output of the comparator will turn ON and the LED will be lit.
