How Many Amps Does A Microwave Transformer Draw
- #ane
Information technology's possible to use microwave transformers to tube amps? Of course that is needed rewinding the secondary, unless that I try to make a amp that need 2.5kV.
I already read about someone that used microwave transformers to obtain 12V at high currents, like 60, 50A... But my question is for tube amps...
I have a few MOTs hither, and thats why I'm asking.
Thank you.
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- #2
Certain, it'southward possible, but probably overkill, but if you lot have some, and the primaries aren't fried, you could do it. If yous're certain of the chief, connect information technology (beware of that HV seconary!) and see how much voltage the heater winding for the magnetron gives you. Then run into how many turns it has to get your volts/plow ratio.
Once y'all know that, and your design nominal voltage(southward) you can replace the HV secondary with any secondary(ies) voltages you require. The "traditional" wire sizing is 700cm (circular mils) per amp for most PTX's. You lot might become 1000cm/A simply to be on the safe side, and run a bit cooler.
I got a some of these MOTs likewise. Some for HV experiments, some for u-wave experimentation, and some fried ones that I might recover the iron from to brand high current choked for a parafeed MOSFET SS blueprint some 24-hour interval.
What y'all need to look out for are the MOTs that include a "magnetic shunt", that has to go, or you demand a unlike MOT. These mag-shunts ruin voltage regulation.
- #3
Many MOTs have a very low turns/volt and draw a lot of idle current. They are not designed to be run for long periods of fourth dimension (hours).
- #4
You'll discover there's two soft iron slugs, that course the magnetic shunt.
I trounce them out with a punch! You tin can make some useful transformers with these after that. They will happily run for hours after these are removed.
- #5
I have punched out the shunts - non easy but possible. I used mine equally plate chokes and power supply chokes. Non really plenty inductance for plate asphyxiate duty though.
Shoog
- #six
Soft atomic number 26 shunts ?
Where is the soft atomic number 26 shunt usually ? betwixt the 2 windings of wire ?
Thanks.
Srinath.
- #seven
I've also seen a couple of MOT's that had a weld that effectively shorted all the laminations together. Volition depend a lot on what you lot are trying to achieve with them, simply I'd expect them to not be particularly quiet in use
- #8
Welded laminations is a quick and convenient method of industry - it may look bad, but the weld is just a very small fraction of core expanse that information technology doesn't unremarkably matter for power applications. Information technology is certainly practical for making very large choke cores (eg. UI style) where the UI gap outer edge is welded (the weld saturates very apace to become like air).
- #9
OK These accept a line of weld on the outer wall in 4 places. It wont matter ?
Now what is noise ? I idea dissonance in a power supply is a agglomeration of ac in dc supply mainly due to cheapo manufacturers under capping. I thought I tin can get clean DC with a big filter cap ...
Absurd.
Srinath.
- #10
The welds won't thing - a cheaper mode to industry en masse, as no need to punch holes in laminations and use bolts/nuts, or to make up a separate clamping encompass which adds cost.
Your noise comment is not quite right, but the topic gets quite complex for hi-fi/esoteric designs. Best to search around a bit for tutorials on ripple voltage and rectifier noise for a much meliorate understanding. For guitar use that recreates the sound of old amps, then ability supply ripple is oftentimes observed as a subtle but good 'input' in to the tone of the amplifier.
- #11
I managed to nick the 110v side in i of the transformers.
Is there a style to repair it. Its not cut through, its basically nicked.
Cool.
Srinath.
- #12
I run into these are all isolated bobbins.....Couldn't one simply start united nations-winding the secondary say 10 winds, Ability upwards & measure....at say ten turns per, But go along on going till your Ac is where you lot want it a bit higher than you lot want information technology loaded, a elementary wirewound............sure on will be puling varnish with information technology as you in-wind but wouldn't that be best?
_______________________________________________Rick.........
- #13
The secondary is wound so freaking tight in there - fifty-fifty if you got rid of all the lacquer, ther is no room. The secondary is the limiting factor. I think it had something like 20,000 windings of 30-33 gauge wire. You will never go one turn out ... you deceit. The all-time way it to cut off the exposed parts. And so sink a drill through the function between the EI core and subsequently you get 3-4 holes per side, y'all can knock information technology away from the wall and knock information technology out. That secondary was auto wound outside and then stuffed with the core laminations.
Now the primary - in that location is a ton of room. Loosen the lacquer and information technology will come autonomously plough by turn. Anyhow my nicked primary, I am not risking the thing bravado. Its been cut out and removed just in case in a round of idiocy I make up one's mind to employ it.
Absurd.
Srinath.
- #14
Mind y'all that isolation is as well made cheap on microwave oven transformers, hence why i end of the secondary is grounded to the core.
The chief winding is close to 1V/turn and in order for it to run for hours without heating it is a good idea to add together additional primary windings.
As someone else as well stated, MOTs were synthetic for run times less than 15 min at full ability, are placed in a well ventilated enclosure and in that location is also a fan near it (mainly for the microwave head though). Information technology is from birth running on the edge of total saturation and is why measures have to be taken in regard to main curlicue.
- #xv
I have run my microwave for over 90 min - not continously, just back to back. A big bowl of rice = 22 min cook time, nosotros do that very very oftentimes. Bigger bowl for say an actress guest = 30 min. I've done 3-4 of those back to back like having a party. In the humid and hot environment information technology lives in I call up its designed very very well for life in audio. Its water and humidity that kills em. Atleast that's what they say when a transformer explodes in Bharat.
But I will add together a 5v fan to cool it.
I have a few questions.
What exactly does that shunt do - to me it looked similar it will siphon off some of the magnetism running through the centre of the EI core. Removing it will get me closer to 1v per turn ? Its already removed and going to be replaced with cardboard or plywood.
Cool.
Srinath.
- #16
So let me get this straight, if I punch out these "extra" laminations it will free things up so I tin can 'spin' the secondary so I tin pull off some turns?
I'll become these out first & see what I've got.
_____________________________________________________Rick........
- #17
The secondary modification is IMHO a ruby-red herring.
If you were able to knock out the shunt laminations - that is a big if - y'all damage the main and it is worthless ... anyhow if you lot go the shunts out. and you can gently unwind the secondary - you would still be left with a 1/2 amp max ... capacity wire with a stride upwards of almost 20X.
The transformer takes 110v @ 10 amp and send out 2000 v @ 1/2 amp. In a thou watt microwave.
Chopping off the secondary is your best bet. Especially if your target is a 50-80v dc supply. Its easy to hand wind a 10-12 awg wire 35-50 turns on the secondary.
If you lot want to turn say 300-500 turns and go a bigger output voltage. I would think you would be better off cutting the transformer open into the E's and I'southward. You'd measure it earlier cutting it open, and then y'all use a winding technique like making or getting a bobbin and winding it. And then putting it back together.
Absurd.
Srinath.
- #xviii
Pics attached.
These are pics I got off the ones I gutted.
That secondary is a imperial mess - I did better on the beginning one than the 2nd simply that was due to the mode it was wound.
Cool.
Srinath.
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