230V power supply to Arduino

[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

[Tibus]

hox much current could you get with a LDO ort step-Down to 5V or 3.3V? 80ma?

[axillent]

@Tibus the output current from SR10 is depends on the capacitor and rectifier. See the table inside the datasheet

with step-down I can get from my prototype about 100mA at 3.3V
with LDO you will get out as many as you get in minus quiescent current of LDO itself

[axillent]

I made a success by replacing polymer capacitor by ceramic one in the usage of SR10
it leads to a dramatical decrease in needed space. I believe that it will be the smallest AC-DC fotprint

But still I have som problems with DHT sensor to work from SR10 (http://forum.mysensors.org/topic/971/small-wall-outlet-sensor-node)

[jeylites]

@axillent

I like the case you are using. Where did you get it from?

[marceltrapman]

@jeylites said:

@axillent

I like the case you are using. Where did you get it from?

It looks like it was printed.

If so, are you willing to share the files?

[axillent]

yes, all cases are printed
sure, I can share if you need
the case developed for a particular custom made PCB

[marceltrapman]

@axillent said:

the case developed for a particular custom made PCB

I understand but the design is still a good starting point :)