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Microwave oven transformers
Tim Wescott wrote: Andrew VK3BFA wrote: John - KD5YI wrote: Tim Wescott wrote: Using 1/2 wave rectification on each one will result in big DC currents in the coils. These DC currents will saturate your cores like nothing else. Hey, Tim - IIRC, there is only one diode attached to the transformer in my microwave. That would mean it is half-wave rectified as it comes from the factory. Yes? Cheers, John No. Its actually a full wave voltage doubler - the tube itself is used as a diode. And there not, strictly speaking, "proper" power transformers - a saturable reactor would be a better description. They use this to current limit the things cheaply - notice the big "Boing" when they switch, noticeable on a low duty defrost cycle. I read an article years ago on using them for powering linear amps -- the first thing you were supposed to do was knock the shunt out of the core. Apparently this is usually quite easy unless it's spot welded, in which case it's quite hard. 73 de VK3BFA. PS - as a self employed electronics technician, working alone, I refuse to work on the things in my business - too many people been lethally zapped by them, and no one nearby to give CPR...... This could be wise -- once you broach the case on one of those things you're into voltages that will deal instant death. But that's the case for just about any tube linear amplifier. -- Tim Wescott Wescott Design Services http://www.wescottdesign.com Posting from Google? See http://cfaj.freeshell.org/google/ "Applied Control Theory for Embedded Systems" came out in April. See details at http://www.wescottdesign.com/actfes/actfes.html This could be wise -- once you broach the case on one of those things you're into voltages that will deal instant death. But that's the case for just about any tube linear amplifier. -- Tim Wescott Wescott Design Services http://www.wescottdesign.com Never thought about it that way Tim - but your quite right. Theres a familiarity with HV linear power supplies that I just dont have with uwave ovens - the linear supplies seem more "ordered" if that makes any sense -(it probably doesnt......possibly I am just seeking ajustification for not repairing them - their usually dirty stinking beasts... and they can throw some INCREDIBLE , mind boggling intermittents at ya...) Andrew VK3BFA. |
#2
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Microwave oven transformers
Never thought about it that way Tim - but your quite right. Theres a
familiarity with HV linear power supplies that I just dont have with uwave ovens - the linear supplies seem more "ordered" if that makes any sense -(it probably doesnt......possibly I am just seeking ajustification for not repairing them - their usually dirty stinking beasts... and they can throw some INCREDIBLE , mind boggling intermittents at ya...) +++++++++++++++++++++++++++ But there are some interesting and useful components to be taken before the remains are moved to the waste dump or perhaps recycling centre. Frank GM0CSZ / KN6WH |
#3
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Microwave oven transformers
Highland Ham wrote: +++++++++++++++++++++++++++ But there are some interesting and useful components to be taken before the remains are moved to the waste dump or perhaps recycling centre. Frank GM0CSZ / KN6WH Andy writes: Absolutely. The electronicc components can be used for a HV transformer, spare HV caps, and the timer is useful as a general purpose timer for a lawn sprinkler or oven reminder....for when your daughter is learning to cook.. The cabinet can be rigged with rubber bands and used to trap small animals in the garden The line cord can be used for many projects, or as a useful strangulation tool for serial killers... There's gold in them thar microwave ovens !!!!!! Andy W4OAH in Eureka ( the organically grown marijuana capital of Texas ) |
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