What's your favorite mains-to-5v block?

What’s your favorite way of getting from mains (110/220VAC) to 5VDC on a pcb? I have no experience with such blocks and need something that I can just drop in (preferably with few or no passives needed) and be off to the races. Current requirements are modest - just enough for an STM32F401 and a couple LEDs.

@ mcalsyn - I use a usb power adapter.

@ Mr. John Smith - me too - but I need something super compact that will fit on a pcb. I know there are modules out there - just wanted a recommendation based on some firsthand experience.

@ cyberh0me - that looks perfect by my oh my those are pricey!





Thanks @ VersaModule - clearly I need to improve my Mouser-search-Fu. :slight_smile:

Just in case, you might need one of these to go along with it…

@ mcalsyn - This might be a useful guide:


I have a number of these powering my home automation devices. They work well and reliable. I have about 15 of them doing lighting and socket control.


If you want really simply and cheap and it just works, these are great.

A few Chinese knockoffs look very similar but Itead listens to their customers and have done some good work to make these reliable and safe with good isolation etc.

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I’ve bought these below they come in a pack of two:

but I haven’t tried them yet…


Very nice and small but not much in the way of isolation on those. There are no slots to increase the creapage distance which is the most common way to do this.

Attached is what the modules I use have. It isolates the AC and DC side very well.


I like that, but it seems larger than the MeanWell modules, using the 0.1 pins for scale. Would a MeanWell with a slot between the two pin sets (AC and DC) be a reasonable choice? I am trying to fit into the size of a night-light, so picture a standard night-light fixture (with AC pins on the back) and containing a PIR, ESP8266 or 32, and a couple LEDs and associated discretes. The idea being that it is a presence/movement sensor and path light. So far, looks like I can run the whole show on 3v3, so I am considering an 600mA meanwell.

Also, have any of you ever case-mounted some protruding US-style mains blades (like you find on nightlights and wall-warts)? Is there a snap-in version? Maybe loose blades that I can design into the 3d-printed case? I just found PC-style recessed stuff on mouser.

@ mcalsyn - making one or many? If you poke around you can sometimes find these for about $10 which has your power & ESP8266 already taken care of. You might could even adapt the enclosure to your needs. Might be a good option if you’re not planning to mass produce.

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Small number, but I am really dead set on a certain aesthetic, so it’s a custom build.