Understanding Arduino Laser Sensor Module Componets

[Andrew74]

Hi my name is Andrew and I'm new to the forum but long time EEVBlog YouTube watcher. I recently have been trying to learn how to create simple circuits by following the Arduino starter examples which has been going well. I have moved on to trying to create a laser sensor project using the KY-008 laser module. This works fine but I want to understand what components they are using to build the module. I linked a picture of the Module below. It looks like fairly simple components but I don't understand what all the jelly bean components are doing. My understanding was that the laser sensors would output a variable voltage depending on how much light is being shined on to it. According to the  oscilloscope it's output for a digital output of 0v or 3v. This digital output is exactly what I wanted for my project. Although, this project is pointless if I don't understand what the Module is doing or how it works to get a digital output.

https://m.banggood.com/Laser-Receiver-Module-Non-modulator-Tube-Laser-Sensor-Module-p-915633.html

Thanks in advanced,
Andrew

[rstofer]

You can chase the traces on the back side of the PCB to come up with a schematic. 

One 10k resistor is in series with the LED and I don't see where there is any on-off signal for the LED so it seems like it is on all the time EXCEPT that a 10k resistor is much too high for the LED to actually turn on.  You'll have to chase this...
The other 10k resistor is pulling the output up to 5V.  The sensor pulls the voltage down.

In the end, it is an on-off type of sensor.  The output is high when the sensor detects the laser and low when it doesn't detect the laser.

The capacitor just provides a little transient reduction and is connected across Vcc and Gnd.

Not much to it...

[Andrew74]

Is this a special sensor that has a digital output? Is it safe to assume the sensor is a phototransitor because it has three legs? Based on my readings there are three lights sensors the photodiode, photoresistor, and phototransitor. Are you able to tell me what type of sensor is used on the module? I would like buy some at a cheaper rate than $5ea. I just don't know what to search on digikey.

Thanks,
Andrew