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Designed and built a working circuit that used an IR diode coupled with a photo-transistor to monitor the food reservoir on a flower.
Designed and built a working circuit that used an IR diode coupled with a photo-transistor to monitor the food reservoir on a flower.
Design
Design
The design of the IR detector consists of an infrared LED, and a photo-transistor that work together as an optocouple. The requirements for the optocouple pair were to have a threshold value to compare against, in order to determine whether or not a bee was at the feeder.
It was decided that for ease of use, to have the threshold permanently fixed in hardware, and leave only the light source intensity adjustable. This would permit flexibility in the system to compensate for lab environment lighting conditions, tolerances in the electronic components and, variances brought up in the construction of each module. Essentially, it allows a technician to calibrate it.
The hardware threshold was set high enough so that direct sunlight would register as a blocked beam. This prevents the sun from falsely indicated a permanently vacant feeder. The technician had to compensate by turning up the intensity of the IR LED to bias the system by holding the output of the photo-transistor above the threshold.
Control Box
Control Box
The IR detectors are all connected to a central control box, where the main power source for the IR system is connected and the intensities of the IR LEDs are adjusted. The control box also serves as a means to connect the hardware to the PC via a digital input/output card (DIO Card). The control box receives the analog signal from the photo-transistor and converts it to the appropriate electrical levels that the DIO Card requires. All circuitry other than the IR LED and the photo-transistor are contained centrally in the control box.
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