Re: Transformer from a microwave oven


Engineer wrote:
> Hi, all...
> This may seem an odd post but I'm an avid re-user and recycler of old
> and/or scrapped electronic stuff (especially tube equipment), so I
> hope all will be clear...
>
> I have just picked over the carcass of a dead microwave oven (free
> junk from a church sale) to get a thermal switch to repair our main
> unit, but that's another story...
>
> I pulled out all the usable bits (not many!) but also the power
> transformer. It has a 1.75 x 1,25 inch core, weighs 9 1/4 lbs, and is
> 120 VAC to a scary 1,925 VAC (measured off load.) The core has two
> magnetic shunts between the windings to give, I think, a degree of
> voltage regulation (I may be able to press or knock them out, but I've
> not tried yet.) The 120 volt primary resistance is about 0.3 ohm; the
> 2 KV secondary is 115 ohms.
>
> Can anyone think of something useful to do with this this transformer.
> All I can come up with is:
>
> 1. Use two of them back to back as a bench isolation transformer (but
> watch the 2 KV floating around!)
> 2. Use as the OPT for a weird single-ended tube amplifier with 3.8
> Kohm plate impedance (rather low) to a 15 ohm speaker (forget about 8
> ohm speakers - too low; also need to isolate the secondary from the
> frame (easy enough to do).)
> 3. Use it with a voltage doubler or tripler for an electrostatic
> filter (would not fit inside most units so serious safety engineering
> required.) Much too big, though.
> 4. Run it off a suitable battery and interrupter (NOT AC mains!) to
> power an electric fence.
> 5. Use it as a choke in a tube power supply. I'm not sure of the
> secondary winding inductance or current rating. Again, isolate the
> secondary.
> 6. Use to replace another failed one <g> Do they ever fail?
>
> That's it. Thanks for all ideas.
> Cheers,
> Roger

HI, I've used them for making test gear. Flash tester (insulation
tester), you can use 1 or 2 with a variac to give you a 2 or 4KV
variable supply. Put a suitable resistor in the high voltage lines to
limit the current to less than 1mA. Fast transient burst generator (emc
test) if you make 1 of these you need a variable 2kv dc supply to drive
the pulse generator, the transformer/diode/cap from the oven is
perfect, you still need the variac, if you build them all together you
can use the same 1.

.

Relevant Pages

  • Re: OT: Transformer from a microwave oven
    ... Engineer wrote: ... > voltage regulation (I may be able to press or knock them out, ... The 120 volt primary resistance is about 0.3 ohm; ... > ohm speakers - too low; also need to isolate the secondary from the ...
    (rec.audio.tubes)
  • Re: OT: Transformer from a microwave oven
    ... Engineer wrote: ... The 120 volt primary resistance is about 0.3 ohm; ... > ohm speakers - too low; also need to isolate the secondary from the ... > power an electric fence. ...
    (rec.audio.tubes)
  • Re: OT: Transformer from a microwave oven
    ... Engineer wrote: ... The 120 volt primary resistance is about 0.3 ohm; ... Use as the OPT for a weird single-ended tube amplifier with 3.8 ... > ohm speakers - too low; also need to isolate the secondary from the ...
    (rec.audio.tubes)
  • Re: Transformer from a microwave oven
    ... "Engineer" ... > Can anyone think of something useful to do with this this transformer. ... > ohm speakers - too low; also need to isolate the secondary from the ... > power an electric fence. ...
    (rec.audio.tubes)
  • Re: Transformer from a microwave oven
    ... Engineer wrote: ... This may seem an odd post but I'm an avid re-user and recycler of old and/or scrapped electronic stuff (especially tube equipment), so I hope all will be clear... ... 120 VAC to a scary 1,925 VAC The core has two magnetic shunts between the windings to give, I think, a degree of voltage regulation The 120 volt primary resistance is about 0.3 ohm; the 2 KV secondary is 115 ohms. ... Again, isolate the secondary. ...
    (sci.electronics.design)