Need help with Sensor

[Kevin Watson]

Originally Posted by Hop_of_752

When we power the detector with 5V and ground and look at the voltage of the output from the detector out, that is the output is not connected to the RC, just the meter, we seem to detect a change from 5 V when there is no signal from the beacon and 4.4V when there is a signal. Is this right? Can someone explain what is going on?

Hey, this is very cool because this is exactly what you should be seeing. With the beacon present, the meter is averaging the the output of the sensor over time. An ideal meter when measuring a +5 volt pulse train will register a voltage equal to 5 * (on time/total time). The output of the sensor, when viewing the type-0 beacon, is on for 9.0ms of every 10ms. plugging this in to the equation results in a voltage of 4.5. On the other hand, the output of the sensor, when viewing the type-1 beacon, is on for 8.0ms of every 10ms. plugging this in to the equation results in a voltage of 4.0. I'll bet your sensor was pointed at the type-0 beacon when you measured your 4.4 volts. If both beacons are in view of the sensor, the voltage will be even lower (3.5v). You can find an illustration of the sensor output here.

-Kevin