0 votes
asked in ESP8266 OLED Starter Kit by (550 points)

This question doesn't fit into the topic choices, so feel free to move it later if needed.

I was intrigued by an article I read by Daniel, where he used a current sensor to monitor his clothes washer and dryer.

I want to do the same thing and am looking at options for the best way to handle the current sensor part.

One (expensive) option is to use a breakout cord like this one on amazon.com:

https://www.amazon.com/dp/B011SLMUBQ/_encoding=UTF8?coliid=I17LNWUK4860K9&colid=2A4MMZ9BUNL0S

The upside of this approach is that it doesn't involve any modification to the built in power cords, and wouldn't look 'hacked', plus it's easy to take with us when we move.

The downside is that each cord is $24USD and I need 2 of them, plus a project box for all the electronics.

This had me wondering if I could squeeze all the parts needed into the outlet box itself.

In the US our plugs are small, and outlet boxes are typically 4"x4" squares. 

This would mean that I could locate the outlet in one half of the box with the other half dedicated to the electronics:

This has led to some interesting design problems I've not had to solve yet:

How to fit the following into a 2"x4"x1.5" area:

  • ESP8266 module of some sort
  • 120VAC to 3.3V DC power supply
  • qty 2 current sensors, must be able to work from 3.3v, which excludes the popular ACS712 based parts 
  • <or> some way to provide both 5 and 3.3 volts in such a small space.

I'd be curious how others have handled Miniaturization of projects, and if there are any suggested components or approaches. 

1 Answer

0 votes
answered by (9k points)

Go for the Sonoff POW: it is ESP8266 based, cheap ($10 per item) and can measure the consumption: 

https://www.banggood.com/SONOFF-POW-DIY-WIFI-Long-Distance-Power-Monitor-Current-Tester-Remote-Control-Switch-Socket-For-Smart-Home-p-1123797.html?p=6R31122484684201508S

The ESP8266 POW can be reprogrammed to fulfill your needs. Maybe I'll find some time to write a post about it. Make sure that 3500W the device supports are enough...

commented by (550 points)
Oh, excellent, I'll have a look at this, watched a video on the wifi switch they make - someone showed how to solder on headers and reflash the chip.
How big is the circuit board on this - would two fit within a 2x4x1.5" space?
commented by (9k points)
The device is rather big, like a cigarette box. So I am not sure if this will fit in the outlet. What I did however was to cut an extension wire in two and attach the middle parts to the SONOFF. Very easy to hide behind your dryer...
commented by (550 points)
true, size wise it would fit perfectly behind, If I remember right, it even had  hole if I wanted to mount it on the rear wall, and extension cords are cheaper than those expensive cords I found.

To use the sonoff, I assume you had to solder headers on the board, or do the more expensive models come with them?

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