ESP8266 Community Forum

- Sat Aug 15, 2015 8:49 am #26059 I've begun my 3-week wait for all of my ESP8266-related kit to make its way from China. Rather than twiddle my thumbs, I have started fleshing out some ideas for projects. One such project is a wifi connected switch that can switch household AC current. If I can keep the whole project reasonably compact, it can be hidden right in the devices it controls (ie. the base of a lamp). The crux of keeping the project compact is the AC-DC conversion.

If this project were centred around a 5V dev board, like an Arduino, I'd use the innards of a USB power supply. I suppose I could still use the USB power supply and an AMS1117 module to drop 5V to 3.3V, but there must be a simple (and cheap) way to go from household AC to 3.3V directly. I always struggle with power as it is well outside my background. Any suggestions would be welcome.

- Sat Aug 15, 2015 9:02 am #26060 http://www.ebay.co.uk/itm/3-3V-5V-9V-12V-AC-DC-DC-DC-Power-Supply-Buck-Converter-Step-Down-Module-new-/251570054433?var=&hash=item3a92be6521

- Sat Aug 15, 2015 2:49 pm #26096 this one does both 5v and 3.3v

http://www.aerial.net/shop/product/161/ ... 5v33v.html

-D

- Sat Aug 15, 2015 4:43 pm #26102 Assuming you know what you are doing, and how dangerous that mains voltage is, and the residual voltages inside a switching PSU etc etc...

I have found that most cheap USB chargers only have a single zener diode that sets the output voltage.

You simply replace it with a different voltage zener to get an different output voltage.

But... Even if you use a 5v to 3v linear regulator, the amount of power you are wasting is quite low.

If you want lower losses and the unit is to be housed in isolation, you could investigate the use of a device like an LNK304, but this does not provide galvanic isolation.