High voltage transformer from a microwave oven Part 1

yeah feel kind of bad about shortchanging everybody and not showing something smoking her arkin so uh this is that microwave oven that finally died and actually it still works but the waveguide cover fried but because it's so old the wife wanted nothing to do with it so it's gonna end up having to be scrapped but I do know this one has a good high voltage transformer in it all right now a word of warning don't take your cover off your microwave don't poke around and your microwave don't fool around with it don't do anything inside of it don't do anything I do this is very dangerous danger high voltage got a big sticker right here anyways well we've got going on here is we've got this high voltage transformer it takes in on the primary takes in 120 volts when it's running and it outputs over 2000 volts on that secondary ac then we have this big capacitor and a big diode in there and that acts as a voltage doubler circuit and takes this output and increases it by a factor of pretty much two and in reality I'm talking about effective voltage is about two thousand volts but because it's a peak to peak it's more like 20 probably around 2,500 2,600 volts so with the voltage of doubling circuit unloaded it could easily have over 5,000 volts going to the magnetron tube here so this is dangerous even when it's unplugged there's a potential that the capacitor could have its charge stored in it so don't fool around with this kind of stuff hey not to get too far off the subject but just for the heck of it I'm gonna take this carousel motor out this is a this is a little motor that actually turns the turntable inside there when the food's cooking and what's nice about these motors is that they're very low rpm 120 volt motors so you can put you can put a cord right on this with a switch okay and that will turn real slowly and you know it doesn't have a huge amount of power but maybe it could be used to make a poor man's welding positioner for small items like if you had a small shaft that you wanted to rotate slowly so you could you could build it up like you know with TIG or something like that it actually even says right on the back here that this is a 2 watt 3 RPM motor 3 revolutions per minute all right let me just summarize real quickly what I can obliged out of this microwave cause I got that turntable motor it's 120 volt AC 3 rpm motor I got all the micro switches in this case I knew that the micro switches and in this case I knew that everything in this microwave was actually still good so I got all the micro switches I even took the fuse holder even the ceramic fuse was still good got the fan motor it's very dusty but it still works fortunately I broke a blade off plastic was get a little brittle from age if you needed a cooling fan running off 120 volts maybe 4 inside of your welder or something like that you might be able to get away with using one of these this is a interesting design on this motor I recognize these types of motors from my days in working on old turntables I'm not talking about belt drive turntables I'm talking about an early photographs they used a motor identical and design to this and it would drive a rubber idler wheel that would run between a thin shaft on this on the motor and it would it would transfer power to the back side edge of the metal platter on those old phonographs typically you would see that type of a phonograph and the big console stereos that many people had back in their houses back in the the 50s and 60s well they cleaned some of the dust off of this motor you can see a little bit better and you can see these large these large copper wires that are wrapped around the section right here and then there's another one right here and I believe if I recall correctly this is what's called a shaded pole magnet motor and the purpose of these copper bands right here is actually to create almost like a dead zone in the magnetic field for lack of a better way to explain it and that's for starting the motor because otherwise the when the motors energized the magnetic field it would just be kind of holding that that rotor captive and you'd have to come along and give it a spin to start it so there's no start capacitor or anything like that in this motor or start winding let me just do this little well I guess technically you could call this winding but it's kind of a neat design but I first saw these on those early phonograph motors and then this is a timer salvaged this out of the microwave I don't know if I'm gonna even have a use for this but it's basically a timer it's got a electric clock motor inside that when you rotate the switch past a certain point it'll energize the clock motor the clock motor will in turn cause this to run down and when it when it's in the on position it will close a set of contacts here and when it's in the off position when it reaches when it runs down to a certain point it'll ring this Bell open the contacts on the switch and also shut off the power to the clock motor so you use that for some kind of a timer and then this little switch right here basically depending on what position this is in this is on the front of the microwave there was a defrost and normal switch and all that this switch does is depending there must be a can mechanism inside here that if this is in the defrost position as this is counting down it will periodically turn on it'll periodically open and close that switch so it'll have the effect of turning the magnetron on turning it off turning it on turning it off and cycling like that so I can't think off the top of my head any particular uses for this but we'll just probably throw it in a junk drawer you never know so here's the high voltage section of the microwave we've got the high voltage transformer which has on this side it has the primary winding 120 volts goes in here and it has two secondary windings it's got a you can see these thin wires up here this is a quite a lot of turns right here to make this a step-up transformer and then you've also got just a few strands of wire that are running around around this core and they actually act as a filament so this is the primary winding okay we saw the connections on the other side this is the secondary winding here and then this wire right here that just kind of well might not be that one isn't it's actually this one right here this will be the filament okay voltage for the magnetron tube so I don't really care about that one so the output of these transformers is typically somewhere around if I recall correctly over it's over 2 kV or 2,000 volts somewhere around 2300 I think - 2700 volts AC and then what they do is they run it into this capacitor this high voltage capacitor and this diode and create a voltage doubling circuit and the voltage doubling circuit will bring this total total voltage to somewhere around five kilovolts or five thousand volts so you get more bang for your buck after it goes through this voltage doubling circuit so I'm gonna try and utilize this voltage doubling circuit for my experiments here and again again it's good good time for me to reiterate this is very dangerous the voltages here can kill you the voltages can arc so you don't even have to come into complete contact with these high voltage leads for you to get shocked so I do not recommend anybody doing this at home the capacitor can store a charge even after it's de-energized so you can still potentially there's a shock hazard present even with this unplugged alright to make my life easier and to avoid any confusion I want to figure out which of these is the which of these wires has to do with the filament the filament voltage is only about three and a half volts AC and I don't need that so I know that this cap right here on the transform is definitely going to be high voltage because that's coming clearly right out of the the winding the secondary high voltage winding on this so this wire right here appears to be the filament one and I could tell because this wire goes directly over to one of the leads on the capacitor but it's the lead that also has the diode on it so I know that's the output side and it also goes directly through this wire up to this went to the magnetron I could tell that because it's got the the right angle connected there on it and also if I look at the schematic on the microwave itself so right off the bat I could take this out of the equation and then there should be a second lead for the filament and it's probably this one here that's disconnected now what I can do is I can take my own meter and I can actually verify that all right now since the lead for the since the winding for the filament voltage is designed to give a very very low voltage only a few volts it's only a few turns of wire and because it's only a few turns of wire or it's gonna have a very low resistance so when I compare if I look at the resistance of this filament winding what I believe to be the filament winding which it is because it's only 2.4 ohms if I compare that to the high voltage winding which has a whole lot of turns of wire which is this tap and then the other termination for that is actually it's internally it's grounded to the transformer actually it's probably right there matter of fact that's it right there there's a tiny wire coming up right here okay kind of hard to see us on the backside there and it's otters right to this log right here which is riveted to the transformer right there all right and look at my hand out of the way and we could see it's a hundred in three ohms okay so since I know that this tap to ground on the transformer is my high voltage winding I'm going to can these filament winding wires because I don't care about them alright so how does the dump the voltage double the circuit wire up quite simple the high voltage comes out of the transformer winding goes through the capacitor and on the output side of the capacitor is where the diode goes to ground so this is gonna have to be grounded and this is your output okay so this would be going to this would be the high voltage go into the magnetron so this is gonna be my output so I know this is gonna have to go here on this tab alright so I know this is going to have to go to this is gonna have to be grounded on the transformer the diode that is so that's gonna have to go here and then off of here we're gonna have to have the other lead for the output alright just a quick recap of how I wired this this lead right here I've got wire to the metal mounting plate of the transformer which is the ground in the circuit which is now where one end of the high voltage secondary winding is terminated to the other end of the high voltage secondary winding is right here that comes in goes through the capacitor the diode goes from that output of the capacitor to and then the high voltage DC output is coming out right here so between here and here is where I'm going to be able to draw an arc now I'm only gonna probably be generating around 5,000 volts so I should be able to get an arc but it might not be that dramatic the other thing is I've got my cord a GFI from my hairdryer I've got that on here and that's gonna limit my current draw on this circuit when I say this was I forgot this is a 15 amp so when I power it up can actually hear the transformer humming I don't know how much amperage it's drawing right now but it's probably pretty low because there's no load on the output there's an initial surge of current as this capacitor charges up that's probably about it but as soon as I start drawing an arc the current drawn the front and the primary circuits gonna skyrocket I wouldn't be surprised if it trips that breaker there's my set up I've got the leads pretty close together I don't know if I'm probably not gonna be able to draw an arc that far apart but the plan is I'll energize the circuit and then I'll use this wooden stick to move this a little bit closer so there you go I bolt the Jarque now didn't take long at all for it to superheat that conductor and start frying that insulation did you see the little spark right there at the end after I D energized it that was the capacitor discharging that little spark right there was that capacitor discharging and that's exactly why this is still a dangerous circuit even after it's powered down there should be an internal bleed or resistor inside that capacitor that takes care of that but it might not be or it might just be that it wasn't quick enough okay so I cobbled together what's called the traveling arc device or more commonly referred to as a Jacob's Ladder and no I don't mean that psychotropic drug that the CIA experimented on u.s. soldiers with that caused them to go insane oh so anyways what's supposed to happen here is if we can establish an arc hopefully the base the distance here is not too far and once an arc is established that will superheat the air around the arc and that will cause the arc to want to actually start to lift up hot air rises and as it travels up eventually it will get to a point somewhere where the arc will no longer be able to be able to bridge the gap of air between the two electrodes here so we can't get an arc to start one two this far apart but once an arc is established and current starts flowing it can actually sustain that arc over a wider distance and at some point it's gonna cut out obviously not way up here we didn't need a lot more voltage to do that maybe a neon light transformer neon light sign transformer or something like that might yield those kind of results so here goes nothing all right so nothing happened big surprise the gap I have at the bottom there is going to have to be reset closer

Channel: Steve Watroba

Views: 453,131

Rating: 4.4742527 out of 5

Keywords: microwave, oven, transformer, high voltage, voltage doubler, arc

Id: N7rqewjD2Ek

Length: 19min 14sec (1154 seconds)

Published: Wed Mar 15 2017