Uss for Microwave Oven xformer? - Page 1
Forum section: electronics / beginners

author: watchmaker
author_rank: Unknown
timestamp: October 12, 2024, 07:48:21 pm
content: I just replaced my microwave.Short of killing myself, is there any reason to hang on to the transformer?

author: Kim Christensen
author_rank: Super Contributor
timestamp: October 12, 2024, 07:54:21 pm
content: People rewind the secondary and make spot welders with those. (Assuming it's an older 50/60 Hz transformer)Otherwise, they are pretty deadly to be playing around with.

author: coppercone2
author_rank: Super Contributor
timestamp: October 12, 2024, 07:57:15 pm
content: it can also be rewound into some kind of inductor, why I don't know, but you can

author: watchmaker
author_rank: Unknown
timestamp: October 12, 2024, 08:10:05 pm
content: Thanks Both. TO the dump it goes.

author: coppercone2
author_rank: Super Contributor
timestamp: October 12, 2024, 08:56:24 pm
content: if you have any money and your serious about a project that is high current usually you would be better off to buy a big transformer for that, because generally what people want to use MOT for in current applications is basically operating at 100% instead of making a transformer that operates comfortably at 70%.so its either gonna be under powered or over loaded, IMO. Then you see projects like parallel MOT which IMO is insane if you have any money for a real transformer.So I think it becomes a project for the broke and boredFor heating applications, you want a bigger transformer to do something impressive that starts to rival a small O/A torch for instance, a MOT is just big enough to bearly make a competition to a blow torch and some bricks that is over complicated and too slow.For welding, basically practical experience tells me, it starts getting useful & impressive when it runs at the maximum current for a outlet. At lower power levels it need to be precise to be impressive, more precise then can usually be built for a project where the 'cost' of a free MOT is substantial enough to outweigh just winding something on a proper core.Is it worth trying to compete at the same power levels as something like a resistance soldering station or cheap spot welder? Once the power level gets somewhat bigger then a MOT you can actually do some heavy labor impressively. Of course figuring out the contacts is still a big expensive pain in the ass. :'(

author: factory
author_rank: Super Contributor
timestamp: October 12, 2024, 09:00:40 pm
content: They are only useful as a doorstop these days, it's not worth the time to remove the coils for scrap, as they tend to be aluminium, quite easy to check though.David

author: IanB
author_rank: Super Contributor
timestamp: October 12, 2024, 09:04:02 pm
content: Quote from: watchmaker on October 12, 2024, 08:10:05 pmYou might want to hold on to it for a few days before you throw it out. There are uses, depending on how much you are into repurposing things. The uses tend to be in the "tinkering" category, but still can be entertaining. For example:

author: CaptDon
author_rank: Super Contributor
timestamp: October 13, 2024, 01:29:55 am
content: I have one that I modified. Be aware the secondary is grounded to the frame at the start of winding. I was lucky because mine was was well insulated at the start of winding and so I could use the secondary in a full wave bridge. I knocked out the magnetic shunts. I did have to add about 20 turns to the primary to get the core out of saturation and likewise lower the secondary voltage. It is my high voltage supply for a ham radio vacuum tube linear amplifier for 3-30MHz. I chose an 8930 from Eimac. It is a 4CX250 with a big plate radiator on it. I have toyed around with 4X150 and 4CX250 tubes and truthfully they all make about the same power. It easily does 300 watts CW, 75 watts AM and about 500 PEP SSB. Because the secondary has a lot of D.C. winding resistance the regulation is poor with changing loads. 1000uf at 2500vdc helps smooth out the sags.