Simple Cheap High Current Power Supply From A Microwave Oven Transformer

[Music] honey so we're going to do some electrolysis for which we need a high current DC supply a problem with high current DC supplies is getting them at the reasonable price I mean I've got a couple of bench supplies but they would max out to three amps and we're going to need something in the region of 20 to 30 amps so it's going to be next to useless for them now I could always buy one even want to spend a few thousand pounds on it but I don't so what I'm going to do is make my own high current supply from our old friend microwave oven transformer this is simply one of the biggest gifts DIY I couldn't think of they're awesome I mean we've already made a plastic repair gun they're spot welder an electromagnet just loads of things we've made from this and we're now about to make our own DC supply this is really cool now I've gone through how to remove the secondary cause in a video I think it's called preparing your MOT transformer or something where we chopped them out so the methodology I use for doing that is in that video and it's such a piece of cake it's a kind of a 5-10 minute job it really is easy and then you end up with a bunch of these that are just one of the most useful things I've come across and in order to get that to be a DC supply we're obviously gonna pull up plug it into the mains so if you're gonna do that protect yourself from the mains get this bit shielded somehow don't go poking at it with a stick once you've got it connected up shielded leave it well alone this bit we're gonna make into a low-voltage high-current now we're gonna make it about 12 volts the reason to our volts is because I want 12 volts you can make it any voltage you like we did make it a 2 volts so we've made one at 1/8 of a volt so there's a whole way you can make these and it's pretty simple stuff you just put a coil of wire in there one coil is going to give you about point eight of a volt two coils give you about two volts and so on what you're interested in really is the amount of current that wire can handle and there's a whole load of wretched wires kicking about what's dead easy to get hold of from the Home Depot or from the electro factors this stuff is called 1.5 millimeter single call it's the cross sectional area of the wire this is a twisted strand wire and it's meant for lighting and that will carry a third I think it's about 20 amps or so don't quote me on it the amp figures are listed in the wiring regulations you look up the cross-sectional area they'll tell you the amps it can carry much more commonly than this which is twin coroners this stuff you get everywhere I'm looking there it is and a little trick for you incidentally if you take the twin core and get it on this flat side and just nip into it with a pair of snips what you can do is separate out the earth which is always uncoated in this stuff and this is a solid wire incidentally so there's the earth right there and if you grab that earth with your snips give it a tug the earth that's like a psalm the pc cable you can strip that really really easily you pull that back we've got that life in neutral missus 2.5 milk cross sectional area so that'll carry something like 36 amethyst in it I want somewhere around about 40 amps or so so I grab some twinkle that was at 6 mil diameter and this will carry 40 amps no trouble at all I stripped that out and that's the stuff I'm going to use but your wire source it's just all over the place is dead easy to get hold of the other side of the twin core I saved through the things this so you sometimes use I only have the 1.5 which is why I didn't use that the length of that is what I'm going to use and I've got 4 meters of it the other thing obviously is missing it's a rectifier if you follow the channel you know that I'm always pulling apart things and this is one that I found in the plasma television it's actually rated at 70 amps particularly it's on this big old chunky heatsink and then it's on this big old chunky heatsink cuz I got that from the television too you can buy them they're not that explained if you can stamp them stab them much better so we have those through this and that is all we need to make our DC power supply now in order to work out how many turns dead simple what I do is just put a couple of turns on stick it on the life turn it on read the voltage tells me what our volt is coming out I happen to know that I need 12 or 13 turns on there of this and that's what I'm going to do I'm going to put 12 turns on that and that will be my 12 volts okay so there it is all wired up now 12 turns of six mil is about all you're gonna get in there is a bit of a struggle to get it in but once you get it in of your daughter now there is no current limit to this the current will be limited by an application and obviously we're going to put an electrolyzer so it's gonna pull Dever current it can pull but it's gonna pull out 12 volts and we can check that easy enough because there is my and if my tails connected up to my voltmeter I've got the voltmeter on AC because obviously we're gonna put AC in we get AC out at the moment oh I do is plug it in I've connected that one to one side of the coil which is the neutral and then the live to the other side of the coil and brick in the live I've got this little switch there's a momentary switch I press that switch I'll get a current if I don't press that switch I won't so I plug those two in stick it into the mains press my switch I'm incidentally I'm wearing these gloves in case I touch any of these men's contacts not for anything else give that a press here at home and it's actually 11 point 2 volts so I have one turn too many in there take a turn out and it'll drop down to 12 volts okay once I've done that no worries at all this side it's 12 volts and it's two bare wires so really I mean I don't recommend you go doing this particularly but here is it fully charged 12-volt car battery this thing can pump out 600 amps in an instant there's the positive there's the negative and I'm not dead I mean you've got ask yourself why the thing about the voltage is it'll only push against a certain resistance if I stuck a bare wire over there I'd weld that wire because the resistance is next to nothing but me I'm a massive resistance so and I hold the positive of the negative of something like 12 volts there isn't enough voltage for that to push through me I could stand here all day long as long as I don't grab a bit of wire I'll dress myself in gen male and stand in a pool of salty water I haven't got a problem handling 12 volts so this side of it even though it's not currently limited to 12 volts it's not to be worried about I mean it's not to be stupid with either you don't want to bridge that gap because there'll be no resistance I mean will arc it will spark like crazy so fix it down don't go mucking around with it but certainly don't be afraid of it this side of it G 240 volt well just take reasonable care wear gloves don't touch it just be reasonable in your care about it and you're gonna be fine beside who cares so I just thought to show you that if a lot of people seem to be worried about things like 12 volt supplies don't understand why once we plug that in and comes out obviously AC we want DC now easiest thing to do is to buy yourself a rectifier you build a rectifier bridge out of 4 diodes again this is rated at 70 amps so plenty for what I want it for on and it's got little pictures on it to tell you what to do there's a plus there - they're a couple of wavy lines in the centre to take your AC so these two go into the wavy lines in the centre and then out of these two we take our plus or minus I'll wire those up give you a cross above it okay so finished where's the tongue there it is dead easy to do I'm not saying it's the world's greatest power supply but it is cheap it is really easy to do and it will certainly deliver the apps may have you put a five hour fuse in this bit you've drawn on more than 50 amps on that side before you blow that fuse you might want to put a 50 amp fuse in line with your live here I guess if you want obviously a little cage on here put a switch on it put a longer flex on it but it's basically done and all it is is the rebound transformer and a bridge rectifier going out to our output and we'll connect our electrolyzer to there it'll deliver 12 volts all day long and it'll easily deliver the 2025 amps we want probably well it'll probably go up to about 60 amps but it certainly 70 amps is where that's going to be problematic don't anymore you'll have to change your bridge rectifier to something higher rating here like I say the max or gap of this is 130 amps before we start burning everything stop be careful what you attach it to because the current limiting is on what you attach it to not this bit here it's no current limiting here at all um but like I say really really cheap really really easy and it will do what we wanted to do so I hope you enjoyed the video thank you very much for watching

Channel: Robert Murray-Smith

Views: 68,483

Rating: 4.9263015 out of 5

Keywords: MOT, Microwave oven transformer, robert, fwg, power supply, murray-smith, transformer, microwave, oven, power, supply, laboratory, lab, workshop, equipment, diy, d-i-y, home, made, built, how to, off grid, energy, alternative, disruptive, technology, science, engineering, project, electricity, electronics

Id: wYJQeqZ-cfY

Length: 10min 0sec (600 seconds)

Published: Wed Jun 03 2020