Converting microwave oven into reel-tape eraser ???

[Dr ZEE]

heh heh ...

Actually I've just got that 'moranic' idea ..lol
Well, funny or not... While I was using one of those hand tape erasers I have, I've found that it's kinda pain in tha' neck.
So first thought was about... is it possible to build a small box which whould contain the electromagnetic field inside, so I could use the eraser in the studio room and not to worry about gear, tapes etc around. Than that idea came to my mind... how about microwave oven box. Maybe it is already built that way, so it will keep the magnetic field 'contained' ????
I guess I should do some "research" on that. Hey guys, do you have any idea? Speak out.
So... I thought, it would be cool, to actually convert the microwave-oven into eraser-"oven" (I've got here one old and ugly in good 'working condition already') by disabling it's microwave section, while keepping the rest of it functional, then to build a special table plate with center pin/holder, which will be mount on the spinning table of the oven (it does speen nicely and slowely already!!! no special design requires ), so then I can place the reel on it, then make some sort of adjustable arm-holder for the eraser, so I can place it nicely and close above the tape (in the style of record-player's arm ), then close the oven, set the timer for. let's say 30/45/60 sec (the timer would make it greate, so after few experiments I would know how long it takes for good clean result)... start the oven, the table is spinning, let's say I have a special on/off switch for 'arming' the eraser - flip it on. , the oven goes off - flip the switch off ---- ola-la-la

LOL, it does sound like a lunatic idea...does not it ...heh heh

anyhow,
what do you guys think.? Do you think it may work? Or do you think it's totally idiotic

The serious part of this is , thou.... it would be cool to have a 'box' right here in the studio room (right next to my computer, the printer's shelf would be a perfect spot for it ), - open the door, place the reel, lower the eraser-arm, close the door, push the botton, get the 'perfectly erased reel out' ...

 

[arjoll]

Sounds like an interesting idea. The oven probably isn't going to contain a magnetic field though. Its designed to contain the 2.4 GHz RF generated by the magnetron, not a magnetic field generated by a bulk eraser.

It could definately be used to automate the process - track down the control circuitry which switched HT to the magnetron and use it instead to switch the supply to your eraser. I wouldn't sit it beside anything that doesn't like a magnetic field though - tapes, monitors, etc. Keep it well away!

Cya
Andrew

 

[Dr ZEE]

It can kill Ya !!!

Andrew, thanks for spending time reading this and your thoughts
After going through some basic tech-info about microwave ovens, how they work and made ... arghhhhhhhhh .... these are not toys! This thing can kill'Ya if you mess with it mindlessly
Also the practicality of it is questionable.... huh!... that's prety usual for most of my "tech" ideas... lol
I still may try to make something... if I get into mood and have time to waste. The idea of having some smoothely/slowely-moving table is kind of interesting..... gotta do some more research etc...

I was trying to find something on the net about how to (if it is possible) to build a magnetic field containing box, like what material to use, how thick etc..., but all I'm finding are some commercial buildings, rooms stuff like that etc..., bunch of theoretical stuff as well...

okey,


Good erasers are so freakin expansive!

 

[Beck]

I like the rotating tray idea. I've seen pro degaussers on ebay, but they are really pricey. A few companies still make them. Buying them new is out of the question for my humble needs. It would be nice to be able to piece something together with a rotating tray.

-Tim

 

[Rstiltskin]

well, you could tape a bunch of them to your body, then get a MRI....

Andrew, thanks for spending time reading this and your thoughts
After going through some basic tech-info about microwave ovens, how they work and made ... arghhhhhhhhh .... these are not toys! This thing can kill'Ya if you mess with it mindlessly
Also the practicality of it is questionable.... huh!... that's prety usual for most of my "tech" ideas... lol
I still may try to make something... if I get into mood and have time to waste. The idea of having some smoothely/slowely-moving table is kind of interesting..... gotta do some more research etc...

I was trying to find something on the net about how to (if it is possible) to build a magnetic field containing box, like what material to use, how thick etc..., but all I'm finding are some commercial buildings, rooms stuff like that etc..., bunch of theoretical stuff as well...

okey,


Good erasers are so freakin expansive!

erasers don't really erase, they just reorient the magnetic fields on you tape, and magnetic fields follow (I think) the inverse square law. meaning twice the distance from the tape, one quarter the strength of the field (I think)

This is one of the things Tesla could not get around with his idea of 'broadcasting power' to the world.

you will need a VERY strong magnetic field to do this from any distance. Of course, you might be able to melt them with a little bacon and cheese.

 

[arjoll]

I was quite fortunate to pick up a couple of bulk erasers from a broadcaster last year - just the box type, not quite as slick as the Teac one I've used at the local Access radio station but they do the job.

Thinking about this a bit more - Dr Zee, yes you need to watch the voltages in a microwave ! You'd want to remove ANYTHING to do with microwave generation, the HT for the magnetron etc. Basically you'd be left with the control ciruitry - timer etc.

You'll need to get a circuit diagram. If its got a mechanical timer then that and the motor are probably all you can safely use - if its electronic then the timer PCB etc, motor and low voltage (probably +5v) power supply.

I'm not familiar with the handheld erasers - probably spoilt with having access to nice bulk erasers for too long - but you'd have to work out how to mount them so that they are reasonably close to the tape. As Rstiltskin has pointed out the field will drop pretty quickly with distance - so what might erase 5-10mm away will probably only partially erase say 25mm away and just kill the highs 50mm away!

In terms of magnetic shielding, you're talking mu-metal. Don't know too much about it, but have just googled it and there's a heap of links there - just remember to google the phrase, i.e. "mu metal" with the quotes so that you get more focused results.

Anyway, if anyone can pull this off it'll be the good Dr Zee! That cassette delay unit looked like a beast, the kind of thing I'd love to fool around with if I had time! I'm just starting to regret throwing that dead Goldstar microwave on the landfill last year !

Cya
Andrew

 

[Rstiltskin]

you have electricity in New Zealand? what next!

I was quite fortunate to pick up a couple of bulk erasers from a broadcaster last year - just the box type, not quite as slick as the Teac one I've used at the local Access radio station but they do the job.

Thinking about this a bit more - Dr Zee, yes you need to watch the voltages in a microwave ! You'd want to remove ANYTHING to do with microwave generation, the HT for the magnetron etc. Basically you'd be left with the control ciruitry - timer etc.

You'll need to get a circuit diagram. If its got a mechanical timer then that and the motor are probably all you can safely use - if its electronic then the timer PCB etc, motor and low voltage (probably +5v) power supply.

I'm not familiar with the handheld erasers - probably spoilt with having access to nice bulk erasers for too long - but you'd have to work out how to mount them so that they are reasonably close to the tape. As Rstiltskin has pointed out the field will drop pretty quickly with distance - so what might erase 5-10mm away will probably only partially erase say 25mm away and just kill the highs 50mm away!

In terms of magnetic shielding, you're talking mu-metal. Don't know too much about it, but have just googled it and there's a heap of links there - just remember to google the phrase, i.e. "mu metal" with the quotes so that you get more focused results.

Anyway, if anyone can pull this off it'll be the good Dr Zee! That cassette delay unit looked like a beast, the kind of thing I'd love to fool around with if I had time! I'm just starting to regret throwing that dead Goldstar microwave on the landfill last year !

Cya
Andrew

NZ and AUS are two places I really want to spend some time in. The people I have come into contact with from there are absolutly super.

I have been to canada, mexico, eng-germ-france-etc, and have no desire to go back(well maybe that little whorehouse in Neuvo Laredo), I hope to get out to that part of the world before americans are uniformly detested, or maybe its too late.

as far as mu-metal goes, unless he is cooling with liquid nitrogen and building a superconducting magnet(really cool, tho, I will admit if he does) I don't think he should have too much trouble with stray magnetic fields. Just don't leave your floppies on top of it.

Did you know almost all modern crt's and televisions have a deguassing coil around them that fires of whenever the power on? and yet many people let floppies sit on top of their monitor with no apparent harm (usually, although floppies suck, usually)

forgive the spelling, its late here (NY time, eastern)

 

[arjoll]

NZ and AUS are two places I really want to spend some time in. The people I have come into contact with from there are absolutly super.

Aw shucks yes, its a lovely part of the world. Especially NZ A bit chilly here this time of year though 5C yesterday, down close to 0C (that's 32F) tonight again and frosts most of this week. Coldest night was -4C I think.

I hope to get out to that part of the world before americans are uniformly detested, or maybe its too late.

It depends whether you're talking Americans as a group, or individuals. We're quite tolerant of the individuals except for Dubya

Did you know almost all modern crt's and televisions have a deguassing coil around them that fires of whenever the power on? and yet many people let floppies sit on top of their monitor with no apparent harm (usually, although floppies suck, usually)

Floppies suck ALWAYS. It makes me cringe when I see them used, let alone stored like this. Magnetic catches in handbags are killer as well (struck one client who could never work out why her backups always verified ok at the time but never worked afterwards - guess how she transported them?).

For most new systems we recommend zip or flash for small clients, DDS or LTO for servers. CDRW is a pain. Floppies just aren't an option!

Anyway that's enough of me hijacking the thread......

 

[ausrock]

Hmmmmm...................if you hear of any more of those bulk erasers being jetisoned, please let me know . I missed one on Ebay Aust., about 6 months ago...........went for a "proverbial song" and I have a quantity of 1" that could do with a good clean some time.

 

[arjoll]

if you hear of any more of those bulk erasers being jetisoned, please let me know

Will put the feelers out; at least you know it'll be the right voltage and have the right plug. They're not light though; the shipping might be expensive, even just across the Tasman.....

 

[ausrock]

You may be right about the shipping, something I would have to think about before committing.

 

[Dr ZEE]

Hi, huys,
just quick note here ...
thanks again to all of you for input here. for what is worth I may try to make something... since I have the oven to screw here I just don't have time now... If I get into it... I'll post here, for fun
That mu-metal material isn't cheap ... , also it is hard to know if it really work well for the situation
I was also thinking about "converting" old record player to some sort of mechanical "automated" erasing machine. It is all laughable, I am sure from practical point.
later,
/respects

 

[Dr ZEE]

on it

If anybody feel like laughing - go for it ..lol, but I'm on it

So I've got my hands on old (about 11 years old or maybe older) GE turntable microwave oven .
Now, the first very NICE surprise was, that I've open the thing and discovered right there an envelope with tech-sheet, all wiring diagrams, some basic info and actually some dignostic instructions etc... - beautiful!!!!
Here's pic:

Next good thing is that the design and wiring is very clear and the high voltage section was easy to 'locate' and remove, while leaving the rest of the 'machine' fully functional.
Here's the picture of the high voltage section and parts to be removed:

I just want one more time to make NOTE! here. Pleas, do not mess with this kind of electronic devices unless you know what you are doing and can discipline yourself. It can be 4000 VOLTS POTENTIAL with respect to ground!!!!!!!!1 It'll kill you!
So do not mess with microwave ovens while plugged in! and make sure the high voltage capacitor is discharged when unplugged and being served, tested or what ever you are doing.
Also the high voltage capacitor may have internal 'self-discharge' shunt resitor , but do not just count on it! NEVER!
********

okey,
so at the moment I have the oven-box, with fully functional timer, inside light, slowely spinning turntable. Great thing is that there is a nice pair of 120V leads - ready to be used for eraser unit, and its power automatically comes on and goes off - perfect!!!

Now I gotta go through some crafting.... I'll post when ever I actually get something done. so far - so good

/respects

 

[Dr ZEE]

now, i'm thinking to myself...(which I have not done yet) but, when I place the eraser inside the oven and power it up ... wiil the turntable motor still running ok? or will the whole timer-section freak-out and die right on the spot???? lol
well, I'll let you know
/later

 

[arjoll]

now, i'm thinking to myself...(which I have not done yet) but, when I place the eraser inside the oven and power it up ... wiil the turntable motor still running ok? or will the whole timer-section freak-out and die right on the spot????

You should be ok, seeing you've got switched mains ready to go. Is it driven by relay or SCR/triac?

When our old Goldstar blew up a couple of years ago it was only failure in the HT (tripped the MCB for the circuit and the RCD for half of the house!), the rest was relatively intact, so chances are all of the timer etc is fine. If the switching is done by electronic means (scr/triac whatever) then you need to check that the inrush current of your eraser won't kill the switching, otherwise find the relay that's switching it, check its ratings and put in a beefier one if required.

Have fun!

 

[Dr ZEE]

first experiment - good

Andrew, thanks again, man ... looks like you are right

Just completed some experimening here. so far so good .
I've made some pics.
Here's pic one:

, what I've done here is as follows:
First I've managed to actually pull the eraser's power cord (in my case it is hand Robins Unieversal Magnetic Tape Eraser) through the 'roof' and then through the 'magetron's hole and out to the timer's area. Then I've connected the eraser's power cord with 120V leads (following schematics... this way I get 120V on these leads when main fuse is ok, oven's thermo cut is ok (below 293F), magnetron's temp. fuse is ok (below 302F), door sensing switch is on (the door is closed) and primary interlock relay is on. ... llots of stuff heh heh ... ... this is a "seriouse machine" )...
I've placed the eraser on pieces of wood, above the turntable's base in the center of the oven's box.
See this pic:

, I've placed a small wood block to hold the eraser's trigger-switch "ON". And I've placed couple of metal screews under the eraser, so to make sure that the eraser is functioning (the eraser's magnet picks up the screws when "ON" and drops when "OFF")
So, I've closed the door. Set timer for 20sec ... pressed "start" - and everything looks like works well. The eraser is on, the table is turning, the counter is ticking, 20second out - everything is "OFF" - YEAH !!! lol

What I was worring about mostly, was that , maybe the eraser's magnetic field somehow will screw the timer's functioning or the electric motor under the table will not work 'normally'. But so far it looks like everything is cool.

Now I gotta move to some sketch design and actual experiment with erasing the tape. I think, before I get myself into crafting the table, pin-holder, eraser holder etc... I need to make something temporary, so I can actually test the "system" in action.
My general idea is illustrated on this pic:

If everything works ok, then I will need to design a nice table-plate with center pin/hoder (and some adaptor for 10" reels), and I need to craft some adjustable eraser holder/arm so it can be placed and fixed in its position very close to reel's flanger, and also to be able to place it in the location for both 7" and 10" reels.... (another words it has to be x-y-z adjustable) I have some thogts on how it may be done...
well, this will take time...

I'll post again, when I get something done there...

be back
/respects

 

[arjoll]

Awesome!

Looks great! Well done.

Its an electronic timer so shouldn't mind about magnetism (and its too far away to be much of an issue anyway), and as you've found there's no problem with the motor.

I'll await the final results with interest!

Cya
Andrew

 

[Dr ZEE]

Looks great! Well done.

Its an electronic timer so shouldn't mind about magnetism (and its too far away to be much of an issue anyway), and as you've found there's no problem with the motor.

I'll await the final results with interest!

Cya
Andrew

Thanks
If my next test fails, then I'll re-name the project to "advanced pizza degausser" and patent it ....

/later,
/respects