Connecting Sonoff BASICR2 (WiFi relay) to 5V standby

[Jenko32]

(Not sure if this belongs in "Hobby Electronics" or "Cases and Power Supplies")

I realized I wrote to much useless information so here's just the question. Is there a problem with powering on something to the 5V standby rail? The device is going to pull constant ~70mA and ~150mA when switched on to trigger a Wake On LAN

 

I've put this Sonoff BASICR2 WiFi inside my PC to create my own Wake On LAN/WAN device to save myself from the motherboard's problems with Wake On LAN (I choose this method even before discovering my motherboard didn't have this option). The device is connected to the USB internal header cause I thought it was always powered since I activated the BIOS option of having USB power always on.

And this is the problem. The USB don't get power when the power is on for the first time (example: connecting power supply cord or switching on the power strip from completely de-powered PC)

[Windows7ge]

Have you thought of using a 5V wall charger?

 

The problem I see with your idea is it may cause the system to be forced on as you would normally short the standby pin to ground to power on the unit. If it's not a direct short to ground then pulling enough mA might trip the PSU on unplanned.

 

 

[Jenko32]

5 minutes ago, Windows7ge said:

Have you thought of using a 5V wall charger?

 

The problem I see with your idea is it may cause the system to be forced on as you would normally short the standby pin to ground to power on the unit. If it's not a direct short to ground then pulling enough mA might trip the PSU on unplanned.

 

 

When the 24 pin connector is inserted on the motherboard 5V is present between ground and the 5v standby pin (checked with a multimeter). I might just try and see what happens, trusting that the PSU manufacturer doesn't have mechanisms in place that exclude more than a few mA to go into the motherboard when the PC is shut down

Theoretically my PSU has 2.5A max output on the 5vsb rail. I don't understand where one would need to use 12.5W from that

[Windows7ge]

It will probably be fine. I can't think of any real reason why max peaks of 150mA would be sufficient to cause harm especially if you're allowed to pull ~500mA when charging a device from USB even when the systems off.