Power supply for max 100mW from powerline (none isolated)

Jul 07, 2005 3 Replies

Hello All,



I need to power a smal circuit (about 3 Volts, 30mA). This circuit need to be powered from the powerline (220VAC). The circuit need not to be isolated from the powerline.



I searched the internet for a simple solution for this, but could not find it. I hope there are special chips that do just this.



Does anybody has an idea?



Any help is welcome.



Thanks and greetings,



Cor Jansen.


3vDC? The simplest solution is a diode and capacitor in series with the line in and another capacitor across the load. You can use a zener to limit the voltage across the load. I have used this for SSRs

I agree but the OP might like to think about what a single component failure outcome might be.

The clearance box at Radio Shack (or equivalent) can be a good source of obsolete chargers going for pence - that is where my "come-in handy" box full of small supplies came from. One of these could possibly meet the requirement.

However: Just for fun (?) I have cracked open a few of them and been surprised to find that a number do have teensy SMPSU boards. Some implement a complex charging profile which often isn't what is required. I suppose that they could be modded but my eyesight isn't up to that any more. The standard mains transformer type is a better bet for this application..

Look at this. It may be useful.

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