TEMT6000 light sensor voltage divider readout Vs. photoresistor voltage divider

Other Hardware General Electronics
27

It looks like you've had good success with the design.

This appears to be the photo transistor module you are using: TEMT6000 Light Sensor Professional TEMT6000 Light Sensor Module Arduino | eBay

I have a few questions about the design.

  1. Why have you chosen a phototransistor rather than an LDR ? The normal advantage of a phototransistor is that it is very responsive but you have anyway a very high latency smoothing algorithm which negates that advantage.

  2. Why are you powering the phototransistor network from a separate power source ? You'll have a problem if the voltage of the separate power supply does not exactly match the Vcc of the ESP32 (and its ADC). Either you don't get the full swing to 4096 (12 bit ADC) or you overshoot and lose the top end.

  3. How are you going to calibrate the midpoint voltage when both sensors in a pair are receiving exactly the same light. Unless the 2 modules are exactly matched (and the power supplies as previously mentioned), it won't be an analog reading of exactly 2048. So, somehow, you have to 'program' the mid point analog reading maybe with a potentiometer or hard code it.