Power lost when driving a 12v@10A heater


I want to be able to control the temperature in my small greenhouse (a shelf with plastic cover) in my yard to maintain temperature around 71-79F at night.

I used the Duemilanove, a relay shield to turn on and off a ATX power supply using the green and black wire. The ATX power supply (rated at 12v/17a) to drive the 12v heater rated at 10A. Other components I used are the ENC28J60 ethershield to connect to wireless bridge (Asus RT-N12 router with the DD-WRT firmware), and the DC-SS500 temperature/humidity sensor.

The problem I encountered is with the 12v (500ma) and a 9v (1A) DC power supply to the Duemilanmove. For some reason, the microcontroller board lose power periodically. When I used the 9v power adapter, the power drop every few mins. When I used the 12v power adapter, the power drop every few seconds. It happens with the heater is turned on. The DC power adapter to the Asus router has no issue of power lost. All the power supply are connected to the 115v AC house socket.

Instead of using a DC power adapter, I used a 9v DC battery and the problem went away. I am at a lost of what is going wrong, and please let me know how to resolve it.



Sounds like you have some faulty AC mains wiring or the AXT power supply is kicking out interference that is killing the other supplies. Try and use mains filters on your smaller supplies.

I figured the problem out after noticed the voltage regulator area of the board felt really hot even with a 12v dc adapter. The voltage regulator may be damaged some time ago when another 12v DC adapter broke down and output more than 24 volts to the controller board. I didn't notice the problem when it was plugged into USB port as it seemed to be working fine.

I am ordering an UNO for replacement.