Sonoff Basic Rebuild to Low Voltage (12V)

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Introduction: Sonoff Basic Rebuild to Low Voltage (12V)

About: Hello! I'm Felix ;)

Hello guys. Wouldn' t it be nice sometimes to control all your appliences and all your stuff with a WiFi smart switch? But often you don' t need to switch 230V AC. If you create a Short Circuit during wiring theres a risk of an electric shock - This can be very dangerous! I looked for a way to switch on/off my LED Strips using a Sonoff without switching 230V of the power supply. So in this Instructable I'm going to show you how to create your very own WiFi Smart Switch for voltages up to 35V DC using only a few components:

-1x SONOFF BASIC 100-230V 10A: https://letyshops.com/r/gearbest-4hoak29358kkco

-1x Small PCB (I cutted a piece of a 2x8cm PCB)

-1x L7805 Voltage Regulator

-2x 103 (10nF) capacitor

-cables (I used 0.14mm²)

-Some solder

Tools:

-Soldering Iron

-Rotary Tool, but a cutter would also do the job as fine :)

So let' s begin!

If you don' t understand some steps, please feel free to ask and watch my YouTube Video!

Stay Creative! ;) ;D

Step 1: Disassemble the Sonoff

Take the Sonoff out of it' s cover. This step should be very easy :) You have to strip of the warranty sticker. The warranty will be lost after this Modification!

Step 2: Locate the Voltage Regulator

You have to find the Voltage regulator. This regulator steps down the +5V to +3.3V for the ESP8266. You can find the regulator (btw. a AMS1117) on the back of the PCB. It is very tiny ;)

Step 3: Soldering Part 1

Now you have to cut two lenghts of 0.14mm² cable. I used about 10 cm, because I wanted to 3d print an enclosure for the new PCB at first, but I later decided to put all the components inside the old housing. Therefore I recommend to use e.g. 5cm. This should be definitely enough. Then you have to solder the red cable (+) to the right terminal of the voltage regulator. The black Minus-wire will then be connected to the left port of the AMS1117. This step would be easier if you tin the cables at first.

Step 4: Making the New PCB

Now you have to cut a small piece out of the PCB. Make it as small as possible. I used my Rotary Tool for this. Of course you can use an oldschool cutter :). Solder the circuit as shown in the scematic and hook the Input wires up to the Input terminals of the SONOFF Basic! Look at the video if you don' t understand what I am talking about :)

Step 5: Cutting the PCB Tracks (Optional)

If you want you can cut the tracks of the PCB that are going to the old transformer (230V to low voltage). You can use for example a cutter or your Rotary Tool to do this.

Step 6: Have Fun!

After closing up the housing you can use it as before, only with the difference that your modified version only can handle up to 35V DC :) Enjoy it ;D

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    19 Discussions

    0
    gctseng
    gctseng

    Question 7 months ago on Step 4

    Awesome mod! I have a question regarding your choice for capacitance values. The datasheet has a reference design that seems to require much higher values. Can you provide any comments so I can understand? Thanks. Looking forward to modding a couple of Sonoffs but wanted to clarify so I can order the right parts.

    0
    idIoT3D
    idIoT3D

    Answer 9 days ago

    Hi gctseng,
    I recommend to refer to the values provided in the manufacterers datasheet! Idk exactly why I used those values but I tested the circuit with those values and seems to work all the time.
    Sorry for my late reply,
    Felix :)

    0
    kasun75758
    kasun75758

    3 months ago

    Great article.Thank you very much.

    1
    NikolasT1
    NikolasT1

    1 year ago

    Is that possible to make it for up to 35V AC ?

    0
    fabiomvs
    fabiomvs

    Reply 7 months ago

    I actually have the same question. In irrigation systems you find it often 24VAC valves that you need to switch. Otherwise I would need a buck converter to convert 220VAC to 24VAC or I should use Sonoff SV instead. Thank you.

    0
    JayA119
    JayA119

    Question 1 year ago on Introduction

    This looks like the source voltage is now low voltage.

    Do you have a way to connect to the mains, but just close an isolated N.O. switch to control low (
    A friend wants to control her gas fireplace, but the wall switch is just interrupting the 24v transformer output to a relay.

    It is a 2-gang box and 120v mains is available for the sonoff, but I don't want to send that down the relay line

    1
    JimJtron
    JimJtron

    Tip 1 year ago

    Have added photos to show where I soldered and show some ebay modules that are pre-built to drop 12v down to 5 v. For isolation from the AC voltage input circuit, I removed the diode bridge and PTC blue disc component. Hope this helps. Regards, Jim

    Brn 5v Grn 0v.jpgebay modules for 12v_5v conv.jpgRemoved diode bridge.jpg
    3
    JimJtron
    JimJtron

    1 year ago

    Gidday Mate.

    Great article.I can confirm that the 5 volt mod works on the Sonoff RF as well but I soldered my wires a little different.In your Step2 picture, your red circle passes over a square hole.

    that is where the RF Receiver module picks up the ground.I found it easy to solder my ground wire there.The 5 volt wire was soldered to the Electro capacitor’s positive lead after tracing the track from the regulator.It’s just to the left of your red circle.It’s easier to solder there I think.Also because the heat from the soldering iron could damage the regulator, I recommend these alternative ‘safer’ solder points.Also discovered that the RF version can learn 2 seperate keyfob transmitters. Anyway, Well done on the article and video.
    Regards, Jim

    1
    AndresM169
    AndresM169

    1 year ago

    hola me di cuenta que el boton se daño como ami se me arrancaron las pistas como puedo reparar el boton gracias

    IMG_0268.JPG
    1
    maxouille34
    maxouille34

    1 year ago

    Hello . I'am french and it is exactly what i search . Could you tell me if it was the same way to a sonoff 4ch v2 ? I have bought one and search to connect only 24v I think it was the same system , i must search the regulator voltage +5vdc and ground .Thanks

    0
    idIoT3D
    idIoT3D

    Reply 1 year ago

    Hello, I have never bought or seen an sonoff 4ch v2. I have searched on the internet and looked for pictures of your model. But the pictures are too small and I can' t read the text written on the components or on the PCB. What you could do by yourself is sending me a picture (close shot) of the PCB. I will help you to find a solution for this purpose. If you want to do it yourself, you can power it up through the 5,5*2,1mm-Port and measure with a multimeter on the PCB to search 5V. You have to do this WITHOUT plugged in 230V!!!!! The relay-terminals should not be connected to any voltage (230V/110V/...). You do this at your own risk! Greetings from Germany to France ;)

    1
    maxouille34
    maxouille34

    Reply 1 year ago

    Hello . Here is 2 pics of the pcb i think it was the same like the Sonoff basic . thanks

    sonoff4chr2.JPGsonoff4chr2_bis.JPG
    1
    maxouille34
    maxouille34

    Reply 1 year ago

    Hello . Thanks for the reply when i received it i send you pics of the pcb . Do you think it was possible that the sonoff basic or this product sonof 4ch work with an input of 24vac and then an outpout 24vac . I want to use one one them to pilot and program a solenoid valve for the garden . It was difficult to find that on the web.

    1
    dleland71
    dleland71

    1 year ago on Step 6

    What a great idea! I made this project and was able to shrink the circuit even smaller by using a very small piece of perf board. Thank you for your Instructable.Sorry, I didn't take any pictures.

    0
    idIoT3D
    idIoT3D

    Reply 1 year ago

    Thank you so much :) Hope you enjoyed and now have fun with your modded Sonoff :D
    Greetings from Germany to you ;)

    0
    dleland71
    dleland71

    Reply 1 year ago

    Bitte.

    1
    seamster
    seamster

    2 years ago

    Nicely done on your first instructable. Thanks for sharing! : )

    0
    idIoT3D
    idIoT3D

    Reply 2 years ago

    Thank you :)