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HazzWold 1993

Mon Mar 01 2010, 10:05AM

Registered Member #2563 Joined: Mon Dec 21 2009, 10:17AM
Location: Australia
Posts: 280

Well its spring cleaning time in our town, so its scavenging time for me, today i went round town and picked up 7 new microwaves, and here's the line up, also picture is a old MOT with cut windings, i use it as a ballast, a 5Kv MOT, and a MOT with the secondary removed, was using it for high current but i took the wire out. ive got alot more of the diodes, several different types too. the magnetron's i really only take the magnets out of.

The four MOTs in one picture i shall be using for a quad MOT supply.

Reckon if i got one more, and if i was to join all of them up minus the 5Kv one, ballast and the one with the secondary removed, i could get some epic arcs
:D
would i need a fairly dedicated 100+ amp outlet or could i use an outlet for each one individually. though that might be asking alot from my houses wiring, since the lights dim with 1 or two MOTs shorted.

radiotech

Mon Mar 01 2010, 05:09PM

Registered Member #2463 Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546

If you had 200ufd of oil caps rated at 330VAC, you could offset about 9 amps at 120VAC 60 Hz.(1 KVAR). Hooking them parallel
to the primary of the MOT, right at the terminals, might aid the regulation and lessen the dimming under load.

That is a wonderful collection of parts. Did you get any other stuff from the ovens like wiring and switches?

HazzWold 1993

Mon Mar 01 2010, 07:35PM

Registered Member #2563 Joined: Mon Dec 21 2009, 10:17AM
Location: Australia
Posts: 280

I kept every single thing out of the microwaves, even the switches, boards and mechanical timers :)

Coherent

Tue Mar 02 2010, 04:44AM

Registered Member #1886 Joined: Sun Dec 28 2008, 02:55AM
Location:
Posts: 73

lol you're just like me. I'll go around picking up all of the tv's, microwaves and other electronics that people leave on the curb during the spring "super garbage days". Even if it's something like a vacuum or washing machine that I don't feel like dealing with I'll go by and clip all of the cords off to keep them. I have boxes upon boxes of salvaged components in the basement.
Like 10 MOTS, MOCS and magnetrons.
Dozens of high voltage diodes, switches and motors from microwaves.
Lots of appliance lights.
A box with like 100 various cords.
Boxes full of random wire.
Like 2 dozen tv main pcb's with the flyblack and other components still on them. I take the board/speakers/degaussing coil out and then return the rest to the curb. These boards are a gold mine whenever I need a common capacitor or resistor. They contain all kinds of good caps and ceramic resistors of every value imaginable.
A few dozen nice speakers.
Like 50 various electron tubes from old tv's.
About a dozen vintage AC flybacks.
Lots of various power transformers.
Several computer power supplies and gold plated ram sticks/cpu's.
Some very nice multiple output switching power supplies.

Yeah I'm an electronics pack rat.

William Monk

Tue Mar 02 2010, 04:53AM

Registered Member #2470 Joined: Tue Nov 17 2009, 05:47AM
Location: Simi Valley, CA
Posts: 43

Seems like lots of people here are like me :)

radiotech

Tue Mar 02 2010, 04:17PM

Registered Member #2463 Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546

Other items to look at are washer/dryers-target the motor-(copper wire) and discarded stoves- (good 240 volt 20 rated switches and heatinf elements)The elements make great burn-out proof 240 volt balast resistors.

Most washer/dryer motors will make dandy alternators if you connect as much capacitive reactance in parallel with them as the motor has when running normally. This mode of operation is known as "induction generator" and a typical 1/3 HP motor can give about 160 watts of clean 60 Hz if driven about 1800 RPM. The sweet spot for the number of capacitor must be found. They will not build voltage under load. Sometimes a 'goose' is needed- While running,
if no output, tickle it 12 volts DC.

The capacitors retrieved from old 40 watt two lamp fluor balasts are good for this.

quicksilver

Tue Mar 02 2010, 10:49PM

Registered Member #1408 Joined: Fri Mar 21 2008, 03:49PM
Location: Oracle, AZ
Posts: 679

I do the same thing. My wife has just about had it. but I have so many things I just can't buy.....I've formed a list (in my head) about all things that do use HV materials. The laser printers and copiers were a good source, but there are some really strange places to find HV parts like stoves and the differing 20yr old BIG TV's.
I don't just pull the MOT and MOC either, those diodes are not cheap!
I only wish there was some simple method to alter the frequency of the caps in a MVO. Those caps (some of them) are not junk. The best microwaves are the commercial ones from restaurants; both in size and quality of material.

radiotech

Wed Mar 03 2010, 12:11AM

Registered Member #2463 Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546

This Aerovox MOC is rated : 1.6uf 1250V 60 Hv 70"C

The frequency rating wont affect the capacity but if changed will affect how they rated it for temp and voltage. It will have 0.75VAR
at 60 Hz 1250 VAC.

quicksilver

Wed Mar 03 2010, 04:09PM

Registered Member #1408 Joined: Fri Mar 21 2008, 03:49PM
Location: Oracle, AZ
Posts: 679

Is there a formula you can use to determine at what frequency (in addition to other factors) would pose a problem in terms of safety?

For instance if that same cap (in parallel with others to share voltage) were to be used in a tank with a NST or a "bug killer" transformer; subjected to that frequency (make up a simple figure like 5Mhz) but the same currant of that NST at 30mA; (let's say a low current) at what point would it pose a serious problem? {The standard NST doesn't have to be the only source certainly. }
Obviously my question is whether they can be used for anything outside a "can crusher" type device? Or is the risk or returns just not adequate such that their use is just too great beyond 60Hz? I've never seen it done so I believed they are just too limited & that's a shame.

I've done some searching on this issue before but never found a formula that would provide information which would allow the expanded use of such a cheap supply of HV caps.

Steve Conner

Wed Mar 03 2010, 04:27PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

What makes caps heat up and explode is simply I2R heating, and that's a function of the capacitor's ESR and the RMS current you try to force through it.

And the RMS current is of course simply related to the voltage you put across the capacitor and the frequency.

Except in a Tesla coil tank circuit, where the answer is usually "somewhere around 50 amps RMS". Yes, even if you only have a 30mA NST.

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