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Need help with microwave transformer for science project


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Posted

Hi. I’m doing a science project in high school, in which I dismantled a microwave, and took the microwave magnetron, capacitor (no need to worry; the capacitor was discharged) and transformer out.

 

Before I go on, the premise of the project was to get a magnetron to emit a microwave, which would be received by a rectenna (composed of an isolated microwave antenna—in this case a wi-fi antenna, connected by wire to a Schottky diode) which rectifies the AC current and turns it into DC current. In other words, wireless power transmission.

 

Now, I’m particularly having trouble with the transformer. I’m planning to hook up the apparatus to a variable power supply, in which in the science classroom, has an outlet that you can put wires into. One hole is for positive current, another is for negative current.

The variable power supply is in one room, the outlet for the two holes is in another.

 

This poses a problem, as I have a normal electrical plug (you know, for common household electrical outlets) for the microwave (which is connected to the control board AND eventually to the transformer). The transformer is a step-up transformer. The input has two flat knobs (almost like those on an normal electrical plug), and the output has other knobs that I was able to connect to the capacitor and the magnetron via wire. I supplied the link to a diagram of the transformer at the end of this post.

 

I’d like to bypass the controls and be able to directly wire the transformer to the variable power supply via the two holes (+ and -) instead of plugging it into the electrical outlet, that way I can directly control the voltage of the current going into the transformer, instead of having a steady voltage from the normal electrical outlet.

 

How can I make this possible? I don’t know how to distinguish between the two input knobs on the transformer (where to plug into positive and where to plug into negative).

 

I was wondering if it was possible I can use 18-gauge wire to connect into the two variable power supply holes, and connect it to the two input knobs on the transformer via alligator clips.

 

Here is the link to a diagram of a transformer that is extremely similar to mine:

 

http://www.gallawa.com/microtech/images/xform.gif

 

Pardon me for the extremely long explanation (more info is better than less).

 

I would greatly appreciate your help.

 

Thanks,

 

Has09

Posted

forget it, you`ll not achieve a variable power MW generator that way, at best you may be able to modulate the MW carrier a little, the magnetron simply has little room for play when it comes to it`s output power, it`s a bit All-or-Nothing.

you`d also need a separate cathode supply voltage too.

Posted

MW is microwave, I guess? (Note that it is also the standard abbreviation for MegaWatt (1E6 W)... and without the opening post (OP) that would actually make sense as well). Never use symbols or abbreviations without explaining them... it is worth the 2 seconds to type it out.

 

On topic again: if you want to vary the microwave's output power, why don't you use the built-in system to vary the power? Most microwaves can vary the power from thawing (unfreezing) to max power (usually 700 W, or 0.7E-3 MW :D ).

Posted

µwave ovens do not vary their magnetron power; their duty cycle (time on and time off) can be step-selected in the medium/low/defrost setting.

Posted
µwave ovens do not vary their magnetron power; their duty cycle (time on and time off) can be step-selected in the medium/low/defrost setting.

 

Some very new very expensive ones claim to alter the power instead of doing on off to reduce to time averaged power.

 

I'm wondering how collimated the microwave generator is in this case, I know the ones in our lab are very different from the ones in microwave ovens so that we can get decent signals over long range (around 10m path length)...

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