Simple WiFi relay board or DIY Sonoff SV /Sonoff 4 channel (1)

In his video nr 107 youtuber Ralph Bacon describes his ‘frustration’ with an ESP8266-01 based wireless relay he got from AliExpress.

Wifi relay with ESP8266-01 and STC15F104 microprocessor

His frustration is understandable as that particular module is needlessly complicated. It seems the ESP8266-01 is mainly there to make the WiFi connection, while the relay is triggered by yet another microprocessor, the STC15F104. Communication between the two is via AT commands, as if the designers thought, how can we make this in the dumbest way possible.

The ‘simple’ relay board

In his follow up video # 110  Ralph describes another, simpler relay board (pictured), that also frustrated him as the manufacturer apparently had not included the necessary pull-up resistors on the Chip Enable and on GPIO0 and GPIO2.

Both videos came in my focus again, when i discussed the ‘simpler’ board with a diy mate and frequent commenter. It is very cheap to buy and once you add the resistors (to make it start up correctly) factually you have a Sonoff SV.
Ofcourse the Sonoff SV is less than 5 Euro (plus shipping), as opposed to the ‘brandless’ relay board only costing some 2.60 euro, so you might as well get the real thing, but it opens some interesting perspectives, especially as I had most of the stuff laying around namely an ESP8266-01 a relay module and a 3.3Volt power module, all fairly cheap. Just a couple of DuPont cables to connect the three, and it should be fine. I know it is all nickles & dimes stuff but lets do a quick calculation.

Total 2.08 euro as opposed to 2.62 euro (in a nicer package), so not really cost effective to ‘DIY’  but if you have the stuff laying around, better to use it than for it gather dust. It also allows you to choose another pin than GPIO2 to drive the relay.
Ralph also offers a program to replace the existing firmware in the ESP8266, as well as a phone app (all found in the description of his video). Ofcourse it is also possible to replace the firmware with MQTT responsive firmware. For that you could e.g. use my Sonoff Touch program, albeit that in line 17, you have to change “TouchLED=12;”  to “TouchLED=2;

But why stop there? the ESP8266-01 has 4 I/O pins, if we ad a small 220->5V power module and a 4 channel relay board, we could make a sonoff 4ch. These cost about 22 Euro. So that would be more rewarding to build.
That however will be for part 2.

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