I had to rethink whole concept of the air speed indicator. Idea was to use stepper motor to move needle to correct angle. Stepper motors are great for precise movement but they have one massive disadvantage, stepper doesn't "know" its own position. Can only move by certain angle from whatever starting position was. To fight issue I came up with idea to add two buttons underneath main face. Holding one of the buttons would simply move needle left/right to allow user to calibrate the needle. Would work but....setting it up every time would be annoying.
New idea.
By looking at the 3d printer I noticed "home" position of the steppers is set by a physical switches on the shafts. I want to avoid physical switches. Using phototransistor QRD1114 could be perfect for the job then. Planning to use it to detect when needle is in 0 knots position.
Features• Phototransistor Output
• No-Contact Surface Sensing
• Unfocused for Sensing Diffused Surfaces
• Compact Package
• Daylight Filter on sens
Description
The QRD1113 and QRD1114 reflective sensors consist of an infrared emitting diode and an NPN silicon phototransistor mounted side by side in a black plastic housing. The on-axis radiation of the emitter and the on-axis response of the detector are both perpendicular to the face of the QRD1113 and QRD1114. The phototransistor responds to radiation emitted from the diode only when a reflective object or surface is in the field of view of the detector.
Full spec here: https://www.fairchildsemi.com/datasheets/QR/QRD1114.pdf
Ordered few of these, cant wait for a delivery!
Ordered few of these, cant wait for a delivery!
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