Determine the approximate Value of the resistor in the Light

Determine the approximate Value of the resistor in the Light-to-Frequency converter circuit. The following is Known: The sensitivity of the Photo-diode is 50nA/fc The circuit oscillates at approximately 90Hz when the illumination is 100fc

Solution

R= 1 kilo ohm

As it is a feedback resistor

and coparator compares to input sinals and gives the highest value of signal as the output.