230V power supply to Arduino

[klim]

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

[axillent]

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

[klim]

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

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

[axillent]

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

[klim]

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?

[axillent]

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

[axillent]

@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

[tbowmo]

@axillent

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

[axillent]

@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

[tbowmo]

@axillent

500mA should also be sufficient for a sensor node, even with a couple of relays, mysensors in GW mode, etc. it's not even near the 500mA limit

[axillent]

sure. sensornode without relays requires 15-20mA
with SSR relay will need +10-15mA for each relay
+50-100mA for each regular relay

[Tibus]

Hello, I'm also searching a way to get 5V from AC to make a beatiful mysensor wallPlug... I'm searching the smallest and cheapest way to do it. My problem is I want to drive a regular relay (a SSR is not very good for plug and other things no?), an atmega328 tqfp, a NRF24 and some other things like a current sensor,... so, I think I need 150ma +-? (100ma for the relay, max 25-30ma for the NRF and arduino and some ma for the status leds,...)

I found here the SR086 but I don't know if I could take 150ma on it.
What is the best way for my projet?

I also found these one but don't know if it ok too :
http://www.newark.com/vigortronix/vtx-214-001-105/ac-dc-conv-fixed-1-o-p-1w-5v/dp/45X5484?ost=VTX-214-001-105

I'm searchin the smallest way because i also would like to make a in wall module for interuptor,... so the VTX above is ok for a wallplug but a bit big for a in wall module... How the cubino for exemple make a DC module so small?

[axillent]

@Tibus your selection is fine. Any one above is also fine

what is you worry?

[Tibus]

@axillent My worry is taking 150ma out of a SR086? Is the SR086 ok to give 150ma?

The VTX is ok but big for an inwall module so is there a good way to get 150ma in 5V from 220VAC in the smallest form factor possible? (or in less than 1cm height?)

I also found these one but a SR086 would be fine for a inwall relay... (but 150ma?)

http://fr.rs-online.com/web/p/alimentations-a-decoupage-integrables/7719379/

[axillent]

@Tibus SR086 able to provide 100mA from 9-50V. For example you can set it to provide 20V and add DC-DC step-down for example based on MP2359. This will give you current-UP benefit at 5V etc. 20V@100mA will give you 5V@360mA maximum with 90% efficiency

My preference in your case LNK306, you can get directly up to 350mA. Using ceramic capacitors and SMD inductors you will fit in 7-10mm height (see one of my picture above)

And at last. Why not SSR? What type of the load do you have?

[Tibus]

@axillent Thank's verry much. I didn't know the current up benefit of a step-down. I think it's the key of my problem!
I'll test the lnk306. Hope It will work for my project.

For my "in wall module", it's just lights so no problem for an SSR. But for the wall plug, The user chose the load they want... so if it's a TV or a washing machine or a power supply, I read an SSR is not verry good for these things...

[axillent]

@Tibus YAW
For LNK take a look for AN37, especially optimization at table 9
an37-linkswitch.pdf

SSR is fine for most of the loads. But you need to follow recommendation of their use and to control limitations (like maximum ratings and heat dissipation)

[axillent]

I'm expecting to receive my SR086 and SR10 this week
I have a plan to run some tests

[klim]

Regarding the SR10 i've already here a few, but just no time to build up something ;-(
The more i'm curious for your results.

[axillent]

@klim I made a test PCB

I succeed to get about 34mA with 1uF capacitor and probably it will provide 40mA stated in the datasheet
it is not possible to use it directly without an additional LDO or step-down because of a very high ripple.
According to my measurement ripple is 2.8V with 12.6V average output (figures in table should be multiplied by 10):

consumed power from AC is 0.8 W with 36mA output
this means 57% efficiency, not bad for such thing