Electrical – Powering ESP8266 from pc atx power supply


I am powering my ESP8266 from an orange/black wire from my pc power supply. When i remove and reattach the CH_PD pin from +3.3V (orange wire) both leds, blue and red, flash shortly then start to dim and the ESP8266 powers off i guess.

What could be the problem?

I am using an Arduino as FTDI, powered from USB.

ESP       ARDUINO     ATX 
TX        RX  
RX        TX
VCC                   3.3V ORANGE WIRE
GPIO2                 3.3V ORANGE WIRE  
GPIO0                 3.3V ORANGE WIRE
CH_PD                 3.3V ORANGE WIRE
RST                   3.3V ORANGE WIRE
GND       GND         BLACK WIRE
          RST         BLACK WIRE

I could not find the datasheet for the power supply but the model is SL500 SW117XC.
It says it can handle 30A on the 3.3V wire. There is one laptop size HDD and an SSD on the same wire. I just connected in parallel inside the PC case. My PC is on during this.

I also had a CD4050BE as a logic level shifter between Arduino(FTDI) TX and ESP RX but thought that was the problem so I removed it.

Best Answer

PC power supplies are unstable when they only have a low load. You can convert a PC power supply into a stable source of low current power but you need to add a dummy load.

Instructions on how to do this are here: http://makezine.com/projects/computer-power-supply-to-bench-power-supply-adapter/

Given the risks involved in modifying a PC power supple I would recommend finding another source of power.