240VAC wires -> USB (no plug) - Page 1
Forum section: electronics / projects

author: lem0nhead
author_rank: Contributor
timestamp: December 27, 2021, 11:08:43 pm
content: Can someone please recommend a way to convert 240VAC (2 wires) to a USB connector?I can only find adapters (that needs to be plugged to a wall socket) or components like Hi-Link which would require some work to convert to USB as intended (+ adding a case).I know there are some wall sockets that have USB output, so perhaps there are some ready circuits for what I wantThanks

author: tooki
author_rank: Super Contributor
timestamp: December 28, 2021, 12:21:38 am
content: Ummm… the thing you mean is a power supply. There’s no way around that. Whether it’s as a plug-in wall adapted (“wall wart”), a PCB module (like the hi-link brand), or industrial power supply (the kind often in a metal box), you still need the power supply. The wall outlets with USB ports simply have a power supply inside.So what exactly is it you need?? What’s wrong with a wall wart?

author: NiHaoMike
author_rank: Super Contributor
timestamp: December 28, 2021, 12:54:03 am
content: Would a USB power supply with a detachable cord be a good fit?

author: sleemanj
author_rank: Super Contributor
timestamp: December 28, 2021, 02:10:25 am
content: I think what you wanted to ask is "where can I get a 240v in to 5v output power supply module that I can build into my own one-off project"?In which case, the answer is, go to your local cheap but not too cheap stuff shop, buy a modestly cheap USB charger, open it up and remove the module from inside it, attach wires as you require and build into your enclosure.

author: ajb
author_rank: Super Contributor
timestamp: December 28, 2021, 04:44:22 pm
content: You can get fairly small encapsulated power supplies that will do 100-240VAC to a range of common DC voltages in PCB-mount or wire tailed version from many of the big power supply manufacturers. Recom, Murata, Meanwell, Cincon, etc. Of course you can probably harvest something for less money, but it's more hassle and harder to do multiples that way. Just be aware that some specify additional capacitance and you likely want some input protection.If you really want something that's ready made for bare wires on one end and a USB port on the other I wouldn't be surprised if someone makes a little DIN-rail mount thing that does exactly that these days.

author: Benta
author_rank: Super Contributor
timestamp: December 28, 2021, 04:56:21 pm
content: Not hard to find, should be available in the closest Home Improvement DIY market.Examples:https://www.conrad.de/de/f/steckdose-mit-usb-1687986.html

author: mariush
author_rank: Super Contributor
timestamp: December 28, 2021, 05:47:56 pm
content: The easiest would be to buy a ready made adapter (wallwart or phone charger) and simply change the cable or just the plug. Some phone chargers come with removable usb cable, they're basically a 5v adapter with a usb type a jack on it.Here's random amazone.de search result example :https://www.amazon.de/-/en/LDT-037-SM-Luoatip-USB-Charger-2-1-Pack-multicolour/dp/B082YR8Y97/If you want to make it yourself, you can buy a small isolation transformer, a bridge rectifer, a capacitor and a linear regulator or a dc-dc converter chip (a dc-dc converter circuit would allow you to use transformers with larger secondary windings ex 12-24v ac, with a linear regulator you need your transformer's output voltage to be close to 5v, maybe 6-9v AC max) and the parts it needs and mount them all on a tiny circuit board and then put everything in a small project case. The problem is such adapter would be much heavier than a switching power supply, as are the typical phone chargers with usb.You would have to know how much current your device would consume and pick the transformer's power rating accordingly.

author: fchk
author_rank: Frequent Contributor
timestamp: January 01, 2022, 03:04:23 pm
content: Quote from: lem0nhead on December 27, 2021, 11:08:43 pmYou MUST use a standard isolated power supply in order to maintain safety and not tripping the RCD. All outlets with built-in USB do have small 5V power supplies. There is absolutely no way around it that passed VDE rules, and if you try otherwise and burn your house down no insurance will cover you.fchkPS: look herehttps://www.busch-jaeger.de/produkt/reflex-si-si-linear/schuko-usb-steckdoseand note the phrase "... und modernem USB-Netzteil ...".