Hi, as my first Arduino project I am trying to detect a simple melody. Therefore I bought UNO R3 (CH340G) and KY 037 sensor (red one with 4 pins, manufacturer HESAI), and now I am trying to get some basic input. I've already read some tutorials and I see that I need to build a pre-amp, but I have trouble getting anything out of that so ATM I'd like to limit points of failure.
I've tried both analog input (A0 connected to A0 on UNO) and digital with threshold, but to no avail. When I use analog read example with plotter I can see that the readings start around 500 and quickly drop to about 280, with some oscilation (about 10 units). Digital read gives me only LOW signal, no matter how I turn the pot on the sensor.
There are two LEDs on the sensor; one is always on as it should signal VCC and GND are connected. When I set the pot too high (turn clockwise - multimeter shows me that I get to maximum at about 70kOhm while the pot should be 100k) the second led turns on, when I get it low it turns off. At about 6-8kOhm the LED faintly blinks when I clasp hands, does not react to whistle or anything better. Okay then, but when reading the digital pin (D0) I don't get anything?
To see if my setup is correct, I've also set up a simple voltage divider using two 10kOhm resistors, and connected the analog pin in between them. Multimeter reads 4.5 volts between VCC and GND (hey, is my USB cable too long? The voltage regulator on board should handle it, shouldn't it?) and 2.25 on the spot where I connected the A0, but when I plot the voltage, I get back to values at 280-290 (while I expect 512 or so). When I pull off some of the resistors I can see a jump by 30 up/down but then it returns to the original value in a couple of seconds.
What am I doing wrong? Btw. I use the GND pin next to digital pin 13 if that makes any difference and 5V in the middle of the power row. I've also tried to use different analog pins but with no difference
Thanks for your hints.