| Electronics > Beginners |
| MOT (microwave oven transformer) cooling. |
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| davelectronic:
I am limited as the property is a 16 floor tower block, I doubt, or through limited ventilation couldn't use a lead acid battery. And it's really just for the fun and something for nothing. Although all told it still cost something. Would a high rated triac type dimmer work ? I know they only convert the wave form. But unsure if that would be suited to an inductive load. I know 1000 watt dimmer type switches are readily available. But will that create heat as it's a modified wave form. |
| Circlotron:
If it’s just for fun then it’s perfectly valid in my books... For a power supply of that current I’d consider using a choke input filter. It will make life easier for the transformer and filter caps, and the ripple will be more or less sinusoidal, not sawtooth, so easier to clean up. Caps and bridge rectifier present a power factor of about 0.6 to the transformer with very high current peaks, but add a choke and those peaks (and the consequent transformer I2R copper losses) go way down. The transformer secondary voltage will have to be higher though. Instead of the dc being 1.414 x the rms volts it will be about 0.9 x the rms. Plus the rectifier voltage drop of course. Back in olde tymes with really serious power supplies the choke input filter was king. |
| bsfeechannel:
MOTs are designed to work under heavy saturation at their rated mains voltage. That's why they overheat without forced air cooling (a.k.a a fan). To "correct" that you have three options: reduce the primary voltage , enlarge the cross sectional area of the center leg of the EI core or add turns to the primary. Since the first option is a bit difficult for you and the second impossible, the third, although a bit crazy, is probably the most viable. By my calculations, to tame that beast you'd need some additional 200 turns on the primary. |
| davelectronic:
I couldn't fit another 200 turns on the primary, just not enough area to add these turns. I'm still wandering about a triac type circuit, I know strictly speaking it doesn't lower the input voltage. But rather cuts off part of the time a certain area of the sin waves on period. Modify the wave form, but unsure if it's a viable option due to heat build up from the modified wave form the triac type unit would supply to the primary. |
| joseph nicholas:
If you use a triac rated for higher power, it should work. Just remember ohms law and you should be ok. I built a soldering iron using a triac and and a MOT and it works well, just get a high power triac, if there is one rated for the job the MOT's will be doing. |
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