Tag Archives: Sonoff low voltage version

More Sonoff

Waiting for the guys in China to come back from holiday, but this turned up today – a low-voltage version of the Sonoff.

At this point I’m going to make some comments based on the PCB – see if you can come up with something better..

Sonoff Low Vottage

Sonoff Low Voltage

The connector bottom left (top photo) shows 5-24v in. Well there is no way that you can shove 24 volts on one of those toy 3v3 regulators so my guess is that the chip top left is a switching regulator working with the round 100uh core to supply maybe 5v to the 3v3 linear regulator (exactly how I do my supplies – I would not wish to put 3v3 switched onto the chip). That leave the ESP over on the right – and it’s FLASH memory underneath.  So no RF here, just a simple relay out low voltage WIFI controller – and providing it is cheap enough – why not. Based on their pricing so far I’m guessing it will be a bargain price.

I’m not sure I entirely understand the generous spacing and cut-outs – unless this board doubles up for mains use elsewhere – it definitely is not intended for mains use here as the inputs go directly to feed the regulator. Having said that, if you removed the 0v resistors which are just out of sight on the top left of the board (and preferably removed the top tracking), then the top input holes and tracking would indeed be completely isolated from the low voltage end – maybe this is intended to be dual purpose.

When Itead come back from hols with some information I’ll be sure to update this blog but I thought you might like a look.  Over on the right is gnd, rx, tx, 3v3 so it would be very easy to re-program this board if you didn’t want to use whatever they’ve put in it (another reason I’m waiting to hear from them). I have already done this using the button held on power up to program – and it works a treat.

Yes of COURSE I’ve taken the label off the relay. It if supposedly rated at 10amps 250v and input 5V – what looks like BKE as the name, So the 5v supports my 5v switched output theory.

More when I find out more.  Just to clarify – this is NOT the same PCB as the Sonoff Pro which uses the same relay but is laid out entirely differently,.

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The Sonoff RF

The Sonoff RF is the new name for the Sonoff with WIFI and RF. I have one of these sitting in front of me – and as you might expect my first thought was to reprogram it (they also do a WIFI only version which I’m more interested in but this is what turned up).

Here (as requested) are pictures of the unit.  WELL it turns out that they changed the pinouts and the large button I was using for programming is no longer attached to GPIO0 -  I HAVE suggested they re-think this – you’ll see in the photo below the hassle I had finding somewhere half usable to trigger off programming – which is done in the ESPs by grounding GPIO0 as you power up. But read on…


See that red line – that’s the best I had come up with until now – shorting these points VERY carefully when applying FTDI power to the board (don’t for HEAVENS SAKE even THINK of doing this with the mains attached) to trigger programming mode. See the 4 way set of holes in the middle – that is ground, serial, serial and 3v3 (the square pad is 3v3).   I used an FTDI with a 3v3 output which had just enough power to run the board and program it.

Here’s another view of the board.


Reader DAVE has pointed out that R21 on the topside can connect GPIO0 to the button – in my case R21 is missing. See above that little square top top right to the right of the 4 way connector – not the large on – the small one – to it’s right are some surface mount components – in mine the centre resistor is fitted, the ones on either side are not – the leftmost of those is R21. Above that is a 0 ohm resistor. Assuming Dave is right, moving that 0r resistor to R21 should restore programming ability to the button – and a quick test with the meter suggests that is correct.

But may I say here – BE CAREFUL – if you’re not familiar with soldering surface mount components – don’t. This board will be self-powered from the mains and last thing you need is dodgy soldering – you could end up with a fire!!

Having said that, I intend to give it a go when my workshop is done. The solution it would seem if you want to DIY program these boards is to get the WIFI only boards.  I can see a use for the RF control if you only have a couple of these in the house but any more and I don’t see the point of the RF.

And here’s what the case looks like..



Hopefully soon I’ll have the WIFI only version – this is the one I’m interested in – I’m hoping the programming output is a little more convenient.  Of course – and this is important – iTead have their own cloud – you don’t HAVE to even open these up – but I’m assuming most people in here want to tinker.

The light incidentally – the green one (the other side in my case had a missing resistor – looks like it was soldered on and then removed – that would be the other colour – I assume red) – anyway, both are POSITIVE based – not ground based… that kept me going for a little while – and they’re not very bright.

Oh, the output to the relay – that is GPIO12 – and 1 is on.