There is literally a video for everything on TH-cam and this is exactly what I needed. I have a project that uses a microwave transformer and I was pretty sure my multi meter wasn’t rated high enough to test out with voltage. Now I know how to test output voltage on a microwave transformer. Thank you.
You can also do it by connecting a multimeter in uA-Range through a large resistor (at least 10 Megaohms) to the secondary and power the transformer like you would do normally. Then calculate the output voltage.
@@enzogaibisso9691 But I guess the way I mentioned is more accurate, since at full input voltage, the core of the microwave oven transformer goes a bit into saturation, which lowers the output voltage a bit. This drop will be something like 5-10%.
Cool! I have always thought transformers have been interesting, with the number of times the primary voltage gets multiplied. Very nice educational video!
I noticed that a lot of MOTs are being scavenged to rewire the secondary as DIY spot welder for Lithium battery tabs where the primary still runs at 120 and the secondary only has up to 3 turns of hefty gauge cable to draw the large current needed. Reversing the connection as you did, equates to the same thing except that the output voltage is about twice while the current is halved. You need about 200A for a 15 mil thick tab. People are using 12VDC, 7Ah LIPO batteries rated at 50C and a control PCB that parallels MOSFETs to drive the timing within milliseconds. You got 6VAC and the microwave is rated at 1200W, so the current should be 200A max.. N Channel MOSFET works on DC, but can drive the 6VAC if one end of the coil is used as COMMON source. It will then see it as a 12V DC wave that is smoothed out using a 220uF 25VDC electrolytic capacitor. The Gate can be driven from a 9V DC battery with its negative connected to the COMMON source. Theoretically, this should works and save us the rewiring time and energy to achieve the same goal. By the way, those PCB spot welder controller only cost lees than $20.
Interesting idea. I always use a variac at 10 % line voltage and then multiply the output of the secondary by 10. But of course, not everyone has a variac so this is a nice alternative.
Thanks I did wonder about the Step Up step down ratio of many Transformers now I have my theories confirmed from your video thank you very much enjoyed it I will like it 4-ever!🙂
Open circuit voltage can be a bit higher than that of a secondary under a load. If you have a HV probe used by TV techs you could measure the output voltage directly. Use caution.
I did this. Pulsed the secondary with a tiny 18650. The primary read like -140v AC! Impossible! Discovered it fried my cheap ACE meter(I miss Radio Shack). So it probably wasnt accurate.
Hey Bill , what accent is that? It sounds like a cross between Irish and Newfoundland. Am I anywhere near? Thanks. Awesome video by the way. Often wondered how to determine the high voltage of the secondary winding on these MOTs.
Putting 2 bulbs of 115V in series with the primary (low side) and use a voltmeter to measure the low side voltage and the high side voltage would give you a more accurate result. I think your error with your technique is erring on the high side. Maybe you could cross-check your results?
My thought was to use another transformer to step down the input voltage to say 12v. 😅 Your way Is much safer and I don't have to do extra math. Also some microwaves use a voltage doubling circuit to bump up to 5000 ish volts.
What if you use two MOT transformers. One to get 2600v and that then feeds the primary of the second transformer. Would that yield 2600v x 21 = 55,000v ??
No, because the primary of the second transformer draws a lot of current so the voltage drops a lot. Such a configuration would actually lower the voltage and power output a lit.
Every microwave transformer might be different, So for 220 volts the transformer is designed to output still the same (around) 2000V Ac if it's designed for 220V on the label
very nice and detail video, could you tell me how to reduce the voltage and increase amps on this transformer, I'm from India and we get 230-240 V from line output. I removed the secondary coil and replaced it with a 25. sq mm copper cable, (thick one) when compared to foreign measurement system. Im trying to melt some metals like iron nails. my question is how to reduce voltage to 2V and increase amps to 500 amps when the line output is around 240V using this transformer. the transformer I have works on 240 V.
Good english and grammar.. but the less amount of secondary windings and bigger the wire gauge, the more the current and less the voltage. For a mot ran at 240v you could use 2 turns of insulated 8 ga stranded wire and should give you around 3v and 800a.. using it to specifically melt things wouldnt be viable as the duty cycle would be less than its intended usage in a microwave.. and short circuiting it all the time melting things would just make it die quicker from overheating.. But does it suck as much as it looks like it does over in india? Looks like it would be overcrowded, stinky from all the people and just a pain to live in. And the weather being so hot in most of the region with a poor power grid wouldnt be too fun either, but ive only been there for a day and a half, nobody spoke english except the english words used to curse and call you names, got my luggage stolen, and somebody literally dropped bird shit on my that he had in a cup.. and tried to get me to pay to clean it off.. i broke his face with a brick and got deported back to America after i got my passport info.. so yea, not a good experience but i bet that dude will think twice before throwing shit on somebody.. lol.. i hit him hard enough to put a flat spot across his cheek and nose.. had to have damn near killed him.. but i stayed with him to make sure he didnt choke on his own blood and told the authorities what and why i did it and they laughed at me and told me next time just make them eat the shit and i wouldnt be arrested.. lol…
The current can be measured safely the normal way. Provided your ampere meter is on batteries. The ampere clamp around the wire works too. Finally, you could measure the current at the primary and assume the same ratio as voltage, in opposite direction, so 20 times lower.
Wattage going in is going to equal wattage going out (minus whatever losses due to inefficiency / heat)... Thus, Ohm's law can calculate the theoretical value...
Transformers are for AC... If you connect DC and have enough amperage available (as in a car battery), you're probably going to burn up the primary wires...
You could take a microwave oven transformer and remove the high voltage winding. Replace it with about 15 turns of wire and measure the voltage. Add or remove a few turns to get 15 VAC out. If you need high current then wind the 15 turns with thick wire.
@@turbo3089 amps depend on the capability of the transformer cores and diameter of wire. If you don't know how to work it out then you shouldn't be messing with this kind of electricity. That being said think about how to determine what voltage and amperage you have. Voltage is determined by the winding ratio, so if you have 120 turns on the I out and 15 on the output then that will give you 15 vollts. Amps are determined by the power handling of the cores and the diameter of the wire. We know that the transformer is typically at least several hundred watts seeing that most microwaves are at least 800watts. Since we all know energy is never created or destroyed we know that 800 watts in gives us 800 watts out (approximately). If you need 15 volts and 15 amps then how many watts is that? 15*15=225 watts. That's easily within the capabilities of the primary winding and the transformer cores so the next thing to look at is if the secondary can handle the amperage you need. 15 amps needs a wire diameter of at least 0.05 inch or about 16 gauge. So what you need is approximately 15 turns of 15 gauge wire. Any lower turns and it won't reach the voltage you need, any thinner wire and it will melt trying to give that many amps. Lastly I want to ask you, what is this power supply for? Because if you are trying to make a DC power supply for something then you're going to have a bad time because when measuring ac voltage you are measuring the average power, because maximum power is only at the peaks of the AC wave everything in between is something less than full power. That 120 volt from the wall is average 120 volts, the peaks actually go up to about 165-170 volts. Same with the 15 volts on the output, it is 15 volts average but it's closer to 21 volts peak, and when using diodes to change it to DC it will reach those peak voltages so you won't have 15v DC you'll have 21v DC. If you tell us what you need it for we can help you a lot more.
@@lazyh-online4839 hello friend. I read your comments about transformers and since electricity is my favourite but not my profession I will ask you for something plelase. Does this transformer give more than 200Watt at 12 volt DC? Thanks
@@gjergjkastro9404 if you can rewind the secondary with nice tightly packed coils then yes, you can get quite a bit of wattage out if you also add about 5 or so turns to the primary.
There is literally a video for everything on TH-cam and this is exactly what I needed. I have a project that uses a microwave transformer and I was pretty sure my multi meter wasn’t rated high enough to test out with voltage. Now I know how to test output voltage on a microwave transformer. Thank you.
Dooood.. You just saved me the cost of a HV probe for my Multi-Meter. Nov I've got funds for an LCR Meter. Thank you
Getting the ratio and multiplying it by the current input voltage. Brilliant formula! Thanks for this very informative video.
Amazingly helpful! Thanks so much for this simple explanation for a simple audience member.
Clever approach, I usually took a 6V power transformer and hooked it to the primary to get the ratio.
You can also do it by connecting a multimeter in uA-Range through a large resistor (at least 10 Megaohms) to the secondary and power the transformer like you would do normally. Then calculate the output voltage.
This way is way safer, but you’re correct
@@enzogaibisso9691 But I guess the way I mentioned is more accurate, since at full input voltage, the core of the microwave oven transformer goes a bit into saturation, which lowers the output voltage a bit. This drop will be something like 5-10%.
Cool! I have always thought transformers have been interesting, with the number of times the primary voltage gets multiplied. Very nice educational video!
That was very informative, I never knew you could do that, thank you Bill for posting this.
Thank You very much... Finally someone with a common sense brain... Great information I was looking for.
That hot MOT looks perfect for your next bug zapper :). Thank you for sharing this tip! Welcome back, and I hope all has been well.
very nicely and comprehensively demonstrated
I noticed that a lot of MOTs are being scavenged to rewire the secondary as DIY spot welder for Lithium battery tabs where the primary still runs at 120 and the secondary only has up to 3 turns of hefty gauge cable to draw the large current needed. Reversing the connection as you did, equates to the same thing except that the output voltage is about twice while the current is halved. You need about 200A for a 15 mil thick tab. People are using 12VDC, 7Ah LIPO batteries rated at 50C and a control PCB that parallels MOSFETs to drive the timing within milliseconds. You got 6VAC and the microwave is rated at 1200W, so the current should be 200A max.. N Channel MOSFET works on DC, but can drive the 6VAC if one end of the coil is used as COMMON source. It will then see it as a 12V DC wave that is smoothed out using a 220uF 25VDC electrolytic capacitor. The Gate can be driven from a 9V DC battery with its negative connected to the COMMON source. Theoretically, this should works and save us the rewiring time and energy to achieve the same goal. By the way, those PCB spot welder controller only cost lees than $20.
Interesting idea. I always use a variac at 10 % line voltage and then multiply the output of the secondary by 10. But of course, not everyone has a variac so this is a nice alternative.
This will work but will result in secondary voltage of 180 to 280 VAC which is dangerous if you don't know what you're doing.
Great information - cleared up a lot of questions - thanks so much for sharing your time and expertise on this matter.
Thanks I did wonder about the Step Up step down ratio of many Transformers now I have my theories confirmed from your video thank you very much enjoyed it I will like it 4-ever!🙂
Pretty sweet video man... I never really had a good way to measure the voltage of a MOT I like this method thanks for sharing....
Bill had the same English teacher as John Malkovich......
Playback speed 1.5x
Open circuit voltage can be a bit higher than that of a secondary under a load. If you have a HV probe used by TV techs you could measure the output voltage directly. Use caution.
Great explanation
Thank you for the video, very clear and usefull information. Clever solution!!
Incredibly useful, thank you very much!
Excellent video! Very helpful. Thank you...
I did this. Pulsed the secondary with a tiny 18650. The primary read like -140v AC! Impossible! Discovered it fried my cheap ACE meter(I miss Radio Shack). So it probably wasnt accurate.
Best video ever. Very informative. 🖒🖒🖒🖒🖒🖒
Hey Bill , what accent is that? It sounds like a cross between Irish and Newfoundland. Am I anywhere near?
Thanks. Awesome video by the way. Often wondered how to determine the high voltage of the secondary winding on these MOTs.
Thanks alot,Sir.
Practical made easy.
Thank you
Can I use a MOT to measure the output of an inverter type microwave? The high voltage out of inverter into secondary to be stepped down.
Genius
Putting 2 bulbs of 115V in series with the primary (low side) and use a voltmeter to measure the low side voltage and the high side voltage would give you a more accurate result. I think your error with your technique is erring on the high side. Maybe you could cross-check your results?
How would two bulbs on the low side effect the output on the high side?
My thought was to use another transformer to step down the input voltage to say 12v. 😅 Your way Is much safer and I don't have to do extra math.
Also some microwaves use a voltage doubling circuit to bump up to 5000 ish volts.
what if we connect to the wrong input and it transforms to 2626.95V
Excellent, my thanks.🇬🇧😷👍
What if you use two MOT transformers. One to get 2600v and that then feeds the primary of the second transformer. Would that yield 2600v x 21 = 55,000v ??
No, because the primary of the second transformer draws a lot of current so the voltage drops a lot. Such a configuration would actually lower the voltage and power output a lit.
Thank you 💐
Nice video :) How much voltage can I get from a microwave transformer if I connect 220V on its output side?
Every microwave transformer might be different, So for 220 volts the transformer is designed to output still the same (around) 2000V Ac if it's designed for 220V on the label
Can one actually use a MOT in reverse as a high current low voltage supply?
You could do that, but it won't output a lot of power, since the secondary coil has a very high inductance that limits the current.
very nice and detail video, could you tell me how to reduce the voltage and increase amps on this transformer, I'm from India and we get 230-240 V from line output. I removed the secondary coil and replaced it with a 25. sq mm copper cable, (thick one) when compared to foreign measurement system. Im trying to melt some metals like iron nails. my question is how to reduce voltage to 2V and increase amps to 500 amps when the line output is around 240V using this transformer. the transformer I have works on 240 V.
Good english and grammar.. but the less amount of secondary windings and bigger the wire gauge, the more the current and less the voltage. For a mot ran at 240v you could use 2 turns of insulated 8 ga stranded wire and should give you around 3v and 800a.. using it to specifically melt things wouldnt be viable as the duty cycle would be less than its intended usage in a microwave.. and short circuiting it all the time melting things would just make it die quicker from overheating..
But does it suck as much as it looks like it does over in india? Looks like it would be overcrowded, stinky from all the people and just a pain to live in. And the weather being so hot in most of the region with a poor power grid wouldnt be too fun either, but ive only been there for a day and a half, nobody spoke english except the english words used to curse and call you names, got my luggage stolen, and somebody literally dropped bird shit on my that he had in a cup.. and tried to get me to pay to clean it off.. i broke his face with a brick and got deported back to America after i got my passport info.. so yea, not a good experience but i bet that dude will think twice before throwing shit on somebody.. lol.. i hit him hard enough to put a flat spot across his cheek and nose.. had to have damn near killed him.. but i stayed with him to make sure he didnt choke on his own blood and told the authorities what and why i did it and they laughed at me and told me next time just make them eat the shit and i wouldnt be arrested.. lol…
Excellent
Умница ! 👏👏👏👍👍👍👌👌👌
Thanks for that analogy.
So how would you go about finding the current of the secondary ?
The current can be measured safely the normal way. Provided your ampere meter is on batteries.
The ampere clamp around the wire works too.
Finally, you could measure the current at the primary and assume the same ratio as voltage, in opposite direction, so 20 times lower.
Wattage going in is going to equal wattage going out (minus whatever losses due to inefficiency / heat)... Thus, Ohm's law can calculate the theoretical value...
Smart idea :)
Yep, this is how I do it too.
Good idea! Usefull
please am 194 resistance on high voltage cable on 200ohm, is supose to be 120 resistance below. kindly advice
@@jamescto6483 i dont understand what help you say?
What happen if 12v dc or less is connected to MOT primary coil
Transformers are for AC... If you connect DC and have enough amperage available (as in a car battery), you're probably going to burn up the primary wires...
Jamie from mythbusters? Is that you?
I'm trying to step down 120 to 15 volts is there anyway I can do it with this that you know of
You could take a microwave oven transformer and remove the high voltage winding. Replace it with about 15 turns of wire and measure the voltage. Add or remove a few turns to get 15 VAC out. If you need high current then wind the 15 turns with thick wire.
I'm assuming it won't be 15 volts and 15 amps would it.
@@turbo3089 amps depend on the capability of the transformer cores and diameter of wire. If you don't know how to work it out then you shouldn't be messing with this kind of electricity. That being said think about how to determine what voltage and amperage you have. Voltage is determined by the winding ratio, so if you have 120 turns on the I out and 15 on the output then that will give you 15 vollts. Amps are determined by the power handling of the cores and the diameter of the wire. We know that the transformer is typically at least several hundred watts seeing that most microwaves are at least 800watts. Since we all know energy is never created or destroyed we know that 800 watts in gives us 800 watts out (approximately). If you need 15 volts and 15 amps then how many watts is that? 15*15=225 watts. That's easily within the capabilities of the primary winding and the transformer cores so the next thing to look at is if the secondary can handle the amperage you need. 15 amps needs a wire diameter of at least 0.05 inch or about 16 gauge. So what you need is approximately 15 turns of 15 gauge wire. Any lower turns and it won't reach the voltage you need, any thinner wire and it will melt trying to give that many amps.
Lastly I want to ask you, what is this power supply for? Because if you are trying to make a DC power supply for something then you're going to have a bad time because when measuring ac voltage you are measuring the average power, because maximum power is only at the peaks of the AC wave everything in between is something less than full power. That 120 volt from the wall is average 120 volts, the peaks actually go up to about 165-170 volts. Same with the 15 volts on the output, it is 15 volts average but it's closer to 21 volts peak, and when using diodes to change it to DC it will reach those peak voltages so you won't have 15v DC you'll have 21v DC.
If you tell us what you need it for we can help you a lot more.
@@lazyh-online4839 hello friend. I read your comments about transformers and since electricity is my favourite but not my profession I will ask you for something plelase. Does this transformer give more than 200Watt at 12 volt DC? Thanks
@@gjergjkastro9404 if you can rewind the secondary with nice tightly packed coils then yes, you can get quite a bit of wattage out if you also add about 5 or so turns to the primary.
Help am in UK how do I get 110v when I put in secondary 240 v ???
Anyone please.
If you don't know the answer to that question you need to stay way from that transformer.
@@HylianOverlord i second that.
Obviously, you need to move the transformer to the US or Canada... :)
2:30 it is wife connected to the wtf???
yeah the suckondary
Thank you