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Nothing000
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How would one set up a circuit where a photodetector closes a switch in a circuit once it detects light?
A photodiode is what you want to use.Nothing000 said:I would probably want to use a PhotoConductor, huh?
Hi 000, I forget if I recommended this book to you already, but "The Art of Electronics" by Horowitz and Hill is a good book to get to augment your early studies. It explains all about photodiodes and current-to-voltage conversion using opamps. Here's wikipedia's entry on photodiodes:Nothing000 said:Hey berkeman. How are you? I am only in my second week of my first circuits course, so could you explain what you just said in slightly more detail.
No. When light hits a photodiode, a reverse photocurrent is generated. This photocurrent is small, so you need amplification to do anything with it.Nothing000 said:Thanks berkeman. I will pick up that book. And I read wikipedia's entry on photodiodes. I have extracted from that article that a photodiode would act just like a switch. The switch is open when no light is detected, and it closes when it detects light. Am I right?
Because that's what I want to do. I want to close a circuit when it detects light, and open it when it is dark.
berkeman said:Depending on the photodector, you would probably bias it up and do a current-to-voltage converter circuit. Then take that output voltage and amplify it a bit to get enough power to close your switch (like a relay?).
A photodetector circuit works by converting light energy into electrical signals. This is achieved by using a photosensitive material, such as a semiconductor, which produces a charge when exposed to light. The circuit then amplifies and processes this charge to produce an output signal.
The main components needed to set up a photodetector circuit include a photodetector, such as a photodiode or phototransistor, a power source, and supporting circuitry such as resistors, capacitors, and amplifiers. Additional components may be needed depending on the specific application.
To calibrate a photodetector circuit, you will need to measure the output signal of the circuit for a known input light intensity. This can be done using a light source with a known intensity and a light meter or oscilloscope to measure the output signal. The measured values can then be used to adjust the circuit as needed to achieve accurate readings.
Several factors can affect the accuracy of a photodetector circuit, including temperature, ambient light, and aging of the components. It is important to consider these factors and calibrate the circuit regularly to ensure accurate measurements.
Photodetector circuits have a wide range of applications, including light sensing and control, optical communication, medical devices, and industrial automation. They are also commonly used in electronic devices such as smartphones, cameras, and optical readers.