230V power supply to Arduino



  • Hi,

    I have a number of sensors powered via 230V USB chargers and it works fine but I would like to have a similar power supply (great if encapsulated) with screw terminals to be placed in a small box.

    Do you have a good option to use? (and if it's easily available in Sweden it's very good :) )


  • Mod

    The one similar to this you can solder on top of your PCB or assemble near your PCB in any case type http://www.aliexpress.com/item/20-pcs-lot-4-8W-400mA-Switching-Power-Supply-Board-Voltage-Regelator-Module-AC-90V-240V/1421878190.html
    5V or 12V version can be easily found



  • I have with succes used these:

    http://www.aliexpress.com/item/Travel-Convenient-EU-Plug-Wall-USB-Charger-Adapter-For-Samsung-Galaxy-S5-S4-S3-Note-3/32220133044.html

    They are really easy to dismatle, and the result is this - https://www.dropbox.com/s/ep43uyve5v0msv6/20141206_214210.jpg?dl=0

    At $1.10 I didn't even think about making my own PSU :)


  • Admin

    What is the efficiency of these "cheap" mains -> 12V/5V converters?

    Also, it means that you need a second regulator (be that a linear, or a switching) from 12/5V -> 3.3V.

    If you KNOW what you are doing, you could use SR036 from supertex, that can deliver 3.3V directly from mains (non isolated output).

    it could probably be used for mysensor connected dimers / light switches on mains. (something where human interface is not needed).

    Again, ONLY if you realy know what you are messing with :)


  • Mod

    @tbowmo said:

    What is the efficiency of these "cheap" mains -> 12V/5V converters?

    they are quite efficient. 5V version can deliver 400mA while unloaded supply consumes only 0.2W

    Also, it means that you need a second regulator (be that a linear, or a switching) from 12/5V -> 3.3V.

    output voltage is defined by output resistor divider. I have an experience on changing 12V output to 5V by replacing a single SMD resistor. Theoretically the same way you can get 3.3V directly from the supply.

    If you KNOW what you are doing, you could use SR036 from supertex, that can deliver 3.3V directly from mains (non isolated output).

    it could probably be used for mysensor connected dimers / light switches on mains. (something where human interface is not needed).

    that is true. I have the experience with SR036 (SR037 provides 5V output) and can say that you will never find smaller supply. But the output current will not exceed 50mA and this will depends on your mosfet output capability. Such a supply consumes about 1W while unloaded. Etc. not that green from the power consumption. This is my one side SR037 supply:
    photo 001.jpg

    if you know what you are doing it is also other choice - linkswitch chips LNK302/304/306. The last one can deliver up to 350mA not isolated power directly 5V or 3.3V. It is as efficient as isolated - unloaded it will consume about 0.2W. A bit bigger than SR036. Easy to construct because you do not need custom transformers. For example Duwi zwave wall switches are using this type of the supply. This is my one side SMD version with regulated output:
    photo 002.jpg

    next one is a classical low frequency transformer. The smallest here http://www.hahn-trafo.com/english/pcb-transformers-bv20.php - BV 201 0128 is ideal to power low power arduino device. It will consume unloaded about 1W. Can deliver about 60mA with linear regulator or about 100mA back regulated at 3.3V output. This one is my light controlling arduino using BV 201 0128:
    IMG_1880.JPG

    and the last one is capacitive supply. Most chinice cheap devices are using this type, most cheap supply:
    08908333.png


  • Admin

    @axillent said:

    that is true. I have the experience with SR036 (SR037 provides 5V output) and can say that you will never find smaller supply. But the output current will not exceed 50mA and this will depends on your mosfet output capability. Such a supply consumes about 1W while unloaded. Etc. not that green from the power consumption. This is my one side SR037 supply:
    photo 001.jpg

    I just took a quick google, where the SR036 showed up, so no in depth analysis of alternatives.

    if you know what you are doing it is also other choice - linkswitch chips LNK302/304/306. The last one can deliver up to 350mA not isolated power directly 5V or 3.3V. It is as efficient as isolated - unloaded it will consume about 0.2W. A bit bigger than SR036. Easy to construct because you do not need custom transformers. For example Duwi zwave wall switches are using this type of the supply. This is my one side SMD version with regulated output:

    That one seems very interesting, for powering arduino things (from an efficiency point of view).

    Only one problem, I don't have the time for it at the moment.. I have to restrict my self, in starting new projects :). So for the moment it's battery powered sensors, that are getting my attention,


  • Mod

    @tbowmo said:

    I just took a quick google, where the SR036 showed up, so no in depth analysis of alternatives.

    SR036/037 is very hard to purchase. Even ebay/ali you will find very limited proposal.
    It seams that Supertex has stopped a production



  • @Hausner said:

    I have with succes used these:

    http://www.aliexpress.com/item/Travel-Convenient-EU-Plug-Wall-USB-Charger-Adapter-For-Samsung-Galaxy-S5-S4-S3-Note-3/32220133044.html

    They are really easy to dismatle, and the result is this - https://www.dropbox.com/s/ep43uyve5v0msv6/20141206_214210.jpg?dl=0

    At $1.10 I didn't even think about making my own PSU :)

    Yes, that is an option. I did it with one and it was pretty easy.

    Also found this https://github.com/openhardwarelabs/arduino-power-supply and I like some parts being isolated/encapsulated .

    https://raw.githubusercontent.com/openhardwarelabs/arduino-power-supply/master/pictures/IMG_8030.jpg


  • Mod

    @jocke4u said:

    Also found this https://github.com/openhardwarelabs/arduino-power-supply and I like some parts being isolated/encapsulated .

    myrra also provides regulated modules without need of external regulator
    for example this one http://ru.farnell.com/myrra/47121/power-supply-3-3v-2-5w/dp/1825772


  • Hero Member

    What kind of protections are embedded?


  • Hero Member



  • SR036/SR037 are discontinued products.
    Take a look at supertex (microchip) SR086 (Fixed 3.3V) or SR087 (Fixed 5V) or SR10 instead.


  • Mod

    thanks for the reference. interesting chip even it requires more external parts than sr036/037
    sr036 is still possible to purchase from China
    sr086 is available only in brand stores like farnel



  • Here i found a size example of that chips:
    power supply

    SR086, SR087 and SR10 you can get at ali too.


  • Mod

    very cool picture! easy to imagine
    SR10 the most interesting for low power
    do you have any links to aliexpress?
    I'm not able to find any new chips



  • Hi, sorry not available at aliexpress anymore, maybe it was just temporary.
    But the SR10 (fqn is SR10LG-G) is available at RS-Components and Alibaba.

    Powering the mcu and some peripherals is ok, but do you know the maximum burst time of the NRF24l01 when sending? As all of the chips are limited in current by a few mA, i'm not shure if it will work reliable. I know that big capacitors can fix such issues, but is it sufficient?


  • Mod

    All is fine) I found them at local seller
    Will be cool to try

    NRF24L01 + MCU needs 15mA
    If you have other things to connect you need to count them too
    for example SSR needs at least +10mA

    I'm currently looking for a small supply for the wall switch build based on arduino.
    So, I will need 15 + 10 = 25mA. Both SR086 and SR10LG can be sufficient,
    SR10LG datasheet has very clear table - power ability is very depends on input capacitor.
    25mA should be not a problem. For 240V you need 0.68uF with full rectifier schema
    For 120V you will need at minimum 1uF with full rectifier schema


  • Mod

    @Hausner said:

    I have with succes used these:

    http://www.aliexpress.com/item/Travel-Convenient-EU-Plug-Wall-USB-Charger-Adapter-For-Samsung-Galaxy-S5-S4-S3-Note-3/32220133044.html

    They are really easy to dismatle, and the result is this - https://www.dropbox.com/s/ep43uyve5v0msv6/20141206_214210.jpg?dl=0

    At $1.10 I didn't even think about making my own PSU :)

    Just got it today and made some tests. Price is cool, but I will not recommend to use this for loads higher than 500mA and also will not recommend to supply arduino without an additional 1000uF capacitor. It is a conclusion from the measurement:

    • without load 5.34V output with 440mV pulsation, 0.1W consuption
    • 10 Om load gives 470mA current 4.74V output with 440mV pulsation, 3.5W consuption
    • 5 Om load gives 848mA current 4.43V output with 520mV pulsation, 6W consuption
    • 3.33 Om load gives 1.06mA current 4.07V output with 880mV pulsation, 7.4W consuption

  • Admin

    @axillent

    What if you place a 3v3 ldo at the 5V output, what is the ripple then, at the different loads?


  • Mod

    @tbowmo said:

    What if you place a 3v3 ldo at the 5V output, what is the ripple then, at the different loads?

    with good ldo supported by sufficient capacitors it can be fine for arduino
    but still I will not recommend to go above 500mA with this supply


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