Hi guys,
I'm building an optical tachometer (as so many people have done) and using a QRD1114 sensor (datasheet: https://www.sparkfun.com/datasheets/BOT/QRD1114.pdf) to calculate the rpm of a toothed pulley wheel (28 teeth). I've sanded the wheel to make the teeth nice and shiny and filled the troughs with black marker to give a big difference in reflected light.
I've set my circuit up as shown here for the sensor: https://www.sparkfun.com/datasheets/BOT/QRD1114.pdf (scroll half way down the page)
When I do an analogue read on the pin attached to my sensor, the voltage isn't very well defined i.e . high's of 3.4V and lows of 0.8V. I know I can change my resistor values for better sensitivity however I want to implement a darlington pair to give a square wave with a nice transition from 0 to 5V on every 1/28 rotation.
How do I go about setting my circuit up? I have been looking at this diagram for a photodiode: http://www.instructables.com/id/Infrared-IR-tripwire-module/?ALLSTEPS however I am struggling to replace the photodiode from the circuit shown here with my QRD1114 sensor. Can I do it this way?
I'm building an optical tachometer (as so many people have done) and using a QRD1114 sensor (datasheet: https://www.sparkfun.com/datasheets/BOT/QRD1114.pdf) to calculate the rpm of a toothed pulley wheel (28 teeth). I've sanded the wheel to make the teeth nice and shiny and filled the troughs with black marker to give a big difference in reflected light.
I've set my circuit up as shown here for the sensor: https://www.sparkfun.com/datasheets/BOT/QRD1114.pdf (scroll half way down the page)
When I do an analogue read on the pin attached to my sensor, the voltage isn't very well defined i.e . high's of 3.4V and lows of 0.8V. I know I can change my resistor values for better sensitivity however I want to implement a darlington pair to give a square wave with a nice transition from 0 to 5V on every 1/28 rotation.
How do I go about setting my circuit up? I have been looking at this diagram for a photodiode: http://www.instructables.com/id/Infrared-IR-tripwire-module/?ALLSTEPS however I am struggling to replace the photodiode from the circuit shown here with my QRD1114 sensor. Can I do it this way?
