Hi folks,
I have a question about designing a circuit which detects whether or not a light bulb is turned off or on. This circuit will be electrically isolated from the light bulb (a standard 60W incandescent). I have to use a dry contact sensor, which reads "open" when it sees a resistance greater than 2600 ohms, and "closed" at anything less than that. My first thought was a photoresistor in series with the sensor, but I can't seem to find one whose resistance will decrease to 2600 ohms in near full light reliably. My second thought is a photodiode, but I am not exactly sure how I would use this. If it's set up for reverse-biased conditions, and the light shines on it, will its resistance decrease? I also am using a voltage source of 3.3V.
Thanks for the help.
I have a question about designing a circuit which detects whether or not a light bulb is turned off or on. This circuit will be electrically isolated from the light bulb (a standard 60W incandescent). I have to use a dry contact sensor, which reads "open" when it sees a resistance greater than 2600 ohms, and "closed" at anything less than that. My first thought was a photoresistor in series with the sensor, but I can't seem to find one whose resistance will decrease to 2600 ohms in near full light reliably. My second thought is a photodiode, but I am not exactly sure how I would use this. If it's set up for reverse-biased conditions, and the light shines on it, will its resistance decrease? I also am using a voltage source of 3.3V.
Thanks for the help.