Hi I'm building an air quality monitor using shinyei ppd42 particulate sensor, DHT22 & ESP8266 to upload to thingspeak. I've had it setup using the ethernet shield running for few months without any issue, so I just want to swap out the ethernet to the ESP8266 wifi module.
My setup is as following for power supply:
9V DC(500mA) -> LD33V voltage regular -> ESP 8266
onboard VCC(have tried Uno & Pro Mini 5V) -> PPD42, DHT22 & low power 0.96" OLED display
The problem is that whenever the ESP8266 is connected, it creates ~80mV transient dip. See attachment for both DSO screenshot measured at the VCC input for the Shinyei sensor, one with and one without the ESP8266 connected. Everything is operational including OLED, DHT22 & ESP8266 are functioning fine, but when ESP8266 is connected, PPD42's reading is way off. According to the
spec sheet, the PPD42 can handle 30mV of ripple. So my goal has been trying to get to that but due to my limited experience, I haven't been able to figure out how
I've multiples of everything, so I've tried swapping out sensors, esp8266 modules, changed to different power supplies(9v, 5v & variable bench PSU), swapped voltage regulator to LM317, adding tons of caps up to few thousands uF without success. Can someone please point me to the right direction to fix the issue? thanks alot!!