Thread: Old microwave
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Old March 14th 07, 12:14 PM posted to rec.radio.amateur.homebrew
Anthony Fremont Anthony Fremont is offline
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First recorded activity by RadioBanter: Mar 2007
Posts: 34
Default Old microwave

N9WOS wrote:
I have an old kitchen microwave unit whose only fault is that the
digital readout is broken. As a neophyte homebrew guy (kits only so
far...Elecraft K2, etc), Is there anything worth salvaging from this
unit?

Thanks!

John
AB8O


Off the top of my head.......

The HV transformer. Output 1 to 2KV at several hundred to a thousand
KVA

HV capacitor 1 to 2+ uF at several KV

HV diode. several KV PRV.

Magnetron..... I don't know what I could do with them, but I keep them
anyway. Maybe if I ever get into plasma physics, or building my own
fusion reactor, I'll be set.

A thermal limit switch that is mounted on the magnetron.

A set of large magnets that is mounted around the magnetron. The outer
magnetron casing can usually be disassembled to remove them. They can
be used to make generators and the like.

If you do remove the magnets from the magnetron, don't throw away the
actual magnetron tube. With out the magnets, it acts like a normal
vacuum tube diode. with a PRV of several KV, and a peak cathode
current of up to an amp, a pare of them would work good in a HV power
supply. Filament voltage is usually a couple volts at a few amps.

Several NO switches on the door for safety interlocks, and timer
control.

A relay, or high power triac for controlling power to the transformer
and magnetron.

A light bulb that lights the inside of the microwave.

A fuse or two. Will save you a trip to town if you have another
project that blows a fuse at an inopportune time.

Sometimes a smaller transformer with about 4 to 12V ac output for
powering the timer/display.

If you are into getting the last drop out of a salvage mission, then
you can usually get a moderate number of transistors and diodes off
the timer/display board.

The only problem I have found with doing the last thing on the list,
is you tear the microwave apart, then the last thing you do is go
after the timer board. When you get done pulling all the parts off of
it, and you test them to find out what they are. (NPN, PNP........)
you find one that is bad.......... Then it hits you........That
component ran the this and that....... That bad component is why the
microwave wasn't working....... Then you have to decide if it is
worth putting it all back together after you find out what
died........ I usually don't.


Good list we could add:
hardware (screws, washers etc)
mains power cord
some models have motorized wave "stirring" or magnetic drive platter turners
keypad for PIC projects

All in all, there's allot of good stuff in one. I shouldn't have thrown my
old one out.