DHT sensor sometimes detect 0 degree when motor DC on

Hello All… i have some problem in my little project. i using DHT 11, Lamp 12VDc, motor 3VDc, relay 2 channel, and external supply (12 and 3 VDc) for lamp and motor. my project is when DHT detect temperature > set point, motor DC ON, and if DHT detect temperature < set point Lamp ON.

so my problem is DHT detect 32 C and make motor DC on, but sometimes DHT detect 0 C. i don’t think the problem in my program, because if i unplug motor DC connection, Serial Moritor show condition of sensor is normal. I conclude the problem in wiring. i trying some wiring but my problem not solved.

maybe someone have an experience like me or someone can solve my problem??

*i dont show program because i think the problem in wiring


Please read the first post in any forum entitled how to use this forum.
http://forum.arduino.cc/index.php/topic,148850.0.html . Then look down to item #7 about how to post your code.
It will be formatted in a scrolling window that makes it easier to read.

Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?

We need to see your code and circuit diagram.
Can you post a picture of your project so we can see your component layout?

Thanks.. Tom... :slight_smile:

I don't show program because I think the problem in wiring

Then we will wait until you do read the forum instructions and post your code as well as the usable photos of the whole assmebly.

Unless you are a professional photographer and know what you are doing, do not attempt to take photos inside.

Take your parts outside in full daylight but not direct sun. Use a real camera able to focus in detail and if it has no "macro" function, keep at least half a metre away and use the (genuine) zoom.

I agree that wiring is the first candidate for the failures. How long are the wires to the sensor and motor? Do you have a freewheel diode over the motor? Additional capacitor at the DHT11?

Circuit design problem. Post a hand drawn schematic (not Fritzing) showing how everything is wired, especially the motor driver and motor power supply.

Post links to the motor, motor driver and specifications of the motor power supply.