Advice for Mains AC PCB - Page 1
Forum section: electronics / general

author: coldfiremc
author_rank: Regular Contributor
timestamp: June 08, 2019, 05:52:36 pm
content: Hi I'm making a step down converter PCB in orcad allegro, that will be directly connected to mains AC. My main doubt is what connector pcb footprint could I use for that.Specs are:InputMains AC: 220V RMS, 50HzLoad: Something around 500WOutFS=10Khzfull DC range4A Maximum DC currentIt's just experimental so, no protections will be used. Currently I put on the output and mains connector a TO-220 Footprint. I know it's undoubtedly insufficient.My current schematic is thisI've made an artwork, with controller aux source included. What you think about AC or DC power Traces? (upper side, left side)thanks

author: Ribster
author_rank: Frequent Contributor
timestamp: June 08, 2019, 05:57:03 pm
content: I would certainly add a fuse.Use a THT connector with 5.08mm spacing.Think about earthing connections and how you are going to mount it on your bench.Make a 3d case for it so no live sections are naked, or screw it into a wooden plate.If you can: use an isolation transformer. This will add some protection..

author: pisoiu
author_rank: Regular Contributor
timestamp: June 08, 2019, 08:02:20 pm
content: Please put 1M resistors in parallel with C10 and C11. It is not wise to let those caps charged after you unplug everything and touch the board.

author: Smallsmt
author_rank: Frequent Contributor
timestamp: June 10, 2019, 02:21:44 pm
content: Your circuit will be a dangerous device!Why don't you use AC / DC converters using transformers to isolate the primary power to secondary DC output?Please take a look on their productshttps://ac-dc.power.com/

author: Arjunan M R
author_rank: Regular Contributor
timestamp: June 10, 2019, 03:16:37 pm
content: Quote from: Smallsmt on June 10, 2019, 02:21:44 pmYeah it is riding on the mains voltage.Input and output of the power supplyMUST BE ISOLATED.

author: Arjunan M R
author_rank: Regular Contributor
timestamp: June 10, 2019, 03:19:31 pm
content: You will getshockif you touch the output.Why don't use a mains transformer and rectifier or a SMPS.

author: HB9EVI
author_rank: Frequent Contributor
timestamp: June 10, 2019, 03:39:23 pm
content: pff, wow that's somethingwhat do you call a 'floating ground'?if that ground on the dc side is connected to mains earth you have a short and the fet will blow skyhigh.since there's no galvanic separation, there's nothing floatingunder 500W load that fet will not last a second.an AC outlet for a DC current is let's say not very cleverafter all: just incredible dangerous that setup - with or without fuse. If you get in touch with either DC or AC side all the fuse is not going to save you - maybe (if available) the RCD in house installation will trip

author: ar__systems
author_rank: Frequent Contributor
timestamp: June 11, 2019, 07:19:59 am
content: 500W, linear regulator? CRAZY.No isolation? NO-NO.No protection against transients?

author: HackedFridgeMagnet
author_rank: Super Contributor
timestamp: June 11, 2019, 07:33:47 am
content: It might be safer to give J8 a sexchange.Quotemmm.. non sequitur, possibly in more than one context.