HOW: Smallest form 240VAC to 9VDC @ 200mA ? - Page 1
Forum section: electronics / projects

author: SL4P
author_rank: Super Contributor
timestamp: July 21, 2016, 12:23:06 am
content: I'm putting together a project - several copies - that is quite small, but the limiting factor on size is the mains power supply. ~9VDC @ 200mANotwithstanding the need for mains isolation and compliance with regulations, I'm looking for ideas on thesmallest, reliable - purchasable / legal - power supply module to stuff in the case with the device.Retail plug-packs are possible, but they carry more plastic than needed, along with obtrusive AC plug-pins which need to be insulated etc.Any thoughts?

author: moffy
author_rank: Super Contributor
timestamp: July 21, 2016, 01:02:31 am
content: The only real way to reduce the size of the transformer (which dominates the plugpak), is to up the frequency. I am sure there are converters, especially for standby supplies that do this.

author: SL4P
author_rank: Super Contributor
timestamp: July 21, 2016, 01:13:55 am
content: I was hoping someone may point to a pre-packaged tiny switcher with all the right specs!

author: zapta
author_rank: Super Contributor
timestamp: July 21, 2016, 01:45:24 am
content: How about this one?http://www.digikey.com/product-search/en/power-supplies-board-mount/ac-dc-converters/4325929?k=pbk+series+ac-dc+converters+power+supplies&k=&pkeyword=pbk+series+ac-dc+converters+power+supplies&pv46=32632&FV=17d400b6%2Cfff40042%2Cfff80229%2C118000e2&mnonly=0&newproducts=0&ColumnSort=0&page=1&quantity=0&ptm=0&fid=0&pageSize=25(I was just searching the internet for miniature ac/dc power supply, there were a few hits).

author: SL4P
author_rank: Super Contributor
timestamp: July 21, 2016, 01:52:56 am
content: Thanks for that - I'd never seen anything like that before.May be perfect.

author: boffin
author_rank: Unknown
timestamp: July 21, 2016, 03:43:33 am
content: OK, can I be devious? Find a (real) modern Samsung phone charger, and hook D+ to D- on the USB; this is how Samsung's fast charge works..The +ve rail will jump from 5v to 9v, and you'll get about an amp.

author: ebclr
author_rank: Super Contributor
timestamp: July 21, 2016, 04:15:09 am
content: https://world.taobao.com/item/44593011532.htm?fromSite=main&spm=a312a.7700824.w4002-9823106140.10.De3mUr

author: JPortici
author_rank: Super Contributor
timestamp: July 21, 2016, 09:05:32 am
content: Quote from: zapta on July 21, 2016, 01:45:24 amWow. what a world we live in.

author: aniket
author_rank: Contributor
timestamp: July 21, 2016, 09:45:38 am
content: You can make a small buck converter using NCP1014 and go with it ....The unit shown does 18V at 150-200mA you can easily make one that does 9V @200mA....and the size is pretty small say 20x40mmRegardsAniket

author: MosherIV
author_rank: Super Contributor
timestamp: July 21, 2016, 09:48:10 am
content: Buck converters do not provide sufficient isolation from mains !

author: aniket
author_rank: Contributor
timestamp: July 21, 2016, 09:56:13 am
content: I know buck converter don't provide isolation buy i thought that SL4P doesn't need isolation.....so posted this....Sent from my Lenovo A7010a48 using Tapatalk

author: Kilrah
author_rank: Unknown
timestamp: July 21, 2016, 10:02:19 am
content: Quote from: boffin on July 21, 2016, 03:43:33 amI'm fairly certain it requires USB negotiation.Shorting D+ and D- is what's been done for years to signal fast charge capabilityon 5V, sometimes even done by cables so there would be loads of non-Samsung devices being fried when connected to Samsung supplies if it was that easy to switch the output to 9V.

author: Ice-Tea
author_rank: Super Contributor
timestamp: July 21, 2016, 11:57:02 am
content: Traco.http://www.tracopower.com/products/browse-by-category/show/ac-dc-power-supplies/encapsulated-modules/tmsb-2/1/#panel1

author: klunkerbus
author_rank: Unknown
timestamp: July 21, 2016, 12:13:23 pm
content: Quote from: zapta on July 21, 2016, 01:45:24 amI thought about using one of those or something very similar a few years ago. Be sure to look at the recommended circuit in the datasheet. These modules aren't exactly a complete power supply. For safety and filtering, the recommended circuit adds a lot of external components to the modules.

author: MosherIV
author_rank: Super Contributor
timestamp: July 21, 2016, 12:24:13 pm
content: QuoteReally???QuoteI thought it was made very clear.

author: HKJ
author_rank: Super Contributor
timestamp: July 21, 2016, 01:24:09 pm
content: Quote from: Kilrah on July 21, 2016, 10:02:19 amOnly half the time, the other half is with resistors.

author: boffin
author_rank: Unknown
timestamp: July 21, 2016, 06:20:17 pm
content: Quote from: Kilrah on July 21, 2016, 10:02:19 amYou're incorrect on your understanding on how the fast charging systems works. The iDevices signal charger->device, the new Samsung are device->chargerHere's my less than scientific discoveries on the subject:Method 1 -- Apple iDevices -- charger to device signallingcharger biases the D+ and D- lines to specific voltages to indicate to the device that it may draw more than 500mA. There's much more detailed info on Adafruit's Mintyboost page:https://learn.adafruit.com/minty-boost/ichargingA 2v / 2v (using 72k:47k dividers from +5) works nicely to tell an iDevice it can charge, at up to an amp.Method 2 -- "Quickcharge" (Qualcomm, modern Samsung) -- device to charger signallingdevice signals/shorts D+ and D- signalling to charger to kick up voltage to 9v (actually can go to 12v as well, not 100% sure on the signalling). There's not a lot of detailed specs out there, but essentially Qualcomm and friends needed a higher power charge system without infringing on Apple's patents (note the direction of the signalling).Method 3 -- Draw until you see the voltage dropsome devices (earlier Samsung/LG) also use a system where they draw 5v and keep drawing more and more current (assuming they couldn't negotiate) until they see the voltage start to drop. This allows things like early Galaxy tabs to charge at 1+Amps from most chargers that support higher current.I'll post a pic of my Samsung charger doing "QuickCharge mode" tonight; but here's a pic of the charger itself, 5v @ 2A or 9v @ 1.67A; but I do remember playing with it and watching it kick up to 9v.Added:now that this has tweaked my brain, I did a little more reading and apparently there is signalling saying "9v please", while I remember seeing something saying dead short = 9v. I'll see what I can get tonight out of it.

author: HKJ
author_rank: Super Contributor
timestamp: July 21, 2016, 06:42:12 pm
content: Quote from: boffin on July 21, 2016, 06:20:17 pmApple has codings for up to 2.4A, the lower ones are not used more.Quote from: boffin on July 21, 2016, 06:20:17 pmQuickCharge support up to 20V, but I have only seen up to 12V and as you write the device must ask the charger to increase the voltage (The protocol is very simple).Older Samsung uses resistor coding like Apple, but with another resistor value.If you want to play with QuickCharge, get this load:http://lygte-info.dk/review/USBmeter%20yzxStudio%20load%20ZL1000%20UK.htmlQuote from: boffin on July 21, 2016, 06:20:17 pmSome devices uses this, but phones usual checks for shorted data pins before doing it, other devices may not.I have tested about 100 usb chargers of different types and know how they code the outputs fairly well. All the mains powered ones are listed here (Including how the code the outputs):http://lygte-info.dk/info/ChargerIndex%20UK.html

author: boffin
author_rank: Unknown
timestamp: July 21, 2016, 08:01:07 pm
content: Quote from: HKJ on July 21, 2016, 06:42:12 pmWell, my response of how it all works pales in comparison to the info on your website. Thanks for posting this.I would be very interested in seeing a single page with all of the methods explained (voltages/signalling)

author: HKJ
author_rank: Super Contributor
timestamp: July 21, 2016, 08:09:30 pm
content: Quote from: boffin on July 21, 2016, 08:01:07 pmThe last table on this page helps a bit on that:http://lygte-info.dk/info/usbPowerSupplyTestHow%20UK.htmlSome of the coding's listed are not used any more.I am working on a more elaborate article on usb charging, but I have no idea when I will publish it.

author: boffin
author_rank: Unknown
timestamp: July 22, 2016, 01:56:40 am
content: OK; set it up, and it does requiring biasing the lines on the USB, but got the Samsung Adaptive Fast Charging up to 9volts on the benchfor 5 volts:leave the D+/D- openfor 9 volts:D+ = 3.3 volts (39k/82k divider)D- = 0.6 volts (47k/6k8 divider)see the attached pics