I’m going insane trying to work this out and I’m hoping someone can help.
I have an Arduino (call it Arduino A) with a LCD Shield being powered by a USB cable from a PC. That works just fine but I want to display the results from the DHT11 (Temperature and Humidity Sensor).
DHT11 has 4 pins, + / data / nc / - with the data one connected to Arduino A. The LCD shield makes is difficult to then power this sensor and eventually I want to hook up some other sensors, so I bought a Ywrobot Power adapter board. This can provide both 3.3v and 5v and the DHT11 works with 3.3v-5v.
Whilst I was waiting for the Ywrobot power adapter board to arrive, I had a spare Arduino (let’s call it Arduino B), which I used to just power the DHT11.
I hooked the DHT11’s + to the 3.3v on Arduino B and the - to Ground on Arduino B. This works great, but I’m using two Arduinos with the second one just doing power. The Ywrobot power arrived and I set it up on a breadboard. I tested it to make sure it was supplying power with an LED. This worked, but when hooking the DHT11’s + and - up to the breadboard, nothing, it didn’t work.
So, I don’t understand why the DHT11 would work when powered by an Arduino but not by the Ywrobot power adapter, which clearly is providing power.
Any ideas ?