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Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc. |
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22nd Jul 2020, 10:40 pm | #1 |
Pentode
Join Date: May 2019
Location: Galway, Republic of Ireland.
Posts: 208
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Tape erasure - bulk
I missed out on one of those lately, which prompts the question - is there any way to bulk erase a tape other than with a commercial item? While waiting for the next one to surface, is there any DIY method?
Many thanks TT |
22nd Jul 2020, 11:37 pm | #2 |
Hexode
Join Date: Dec 2018
Location: Sheffield, South Yorkshire, UK.
Posts: 364
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Re: Tape erasure - bulk
For what format of tape
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23rd Jul 2020, 1:41 am | #3 |
Pentode
Join Date: May 2019
Location: Galway, Republic of Ireland.
Posts: 208
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Re: Tape erasure - bulk
Thanks. I have only 1/4 inch type, in various reel sizes. 3 inch, 5, 5-1/4 (?) and 7
TT |
23rd Jul 2020, 6:41 am | #4 |
Octode
Join Date: Mar 2006
Location: Lund, Sweden
Posts: 1,632
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Re: Tape erasure - bulk
I've got one of those handheld bulk erasers, and it's basically a transformer with EI laminations where principally the I laminations are missing and all E laminations are facing the same way (I think in most transformers the E and I laminations are interleaved). I think it has been suggested here on the forum to build one oneself by taking a (large) transformer, removing all the laminations and then inserting only the E laminations.
That said, handheld bulk erasers are not ideal, it takes a bit of skill to properly erase the recording. I'd love to test one of those hefty Weircliffe bulk erasers; basically the magnet is similar but much wider so erases the tape in one pass. For that reason I think it would be really awkward to build one oneself using readily available transformer parts. Last edited by ricard; 23rd Jul 2020 at 6:48 am. |
23rd Jul 2020, 7:00 am | #5 |
Octode
Join Date: Dec 2017
Location: Morden, Surrey, UK.
Posts: 1,558
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Re: Tape erasure - bulk
Well, you could emulate the Leevers Rich Leeraser by rearranging the laminations of a reasonable size mains transformer to an E formation then rewinding the bobbin with as much suitable diameter wire as you can fit.
The erasing field will be across the open side of the laminations. You would have to calculate the number of turns you needed for the minimum inductance then size the wire to fit the winding area. Leevers Rich stopped making their original model because the peculiar size wire they needed (22.5 SWG?) was no longer available - then when metric sizes became the norm something more normal was usable. I`d be inclined to wait for something to become available - they crop up fairly regularly. |
23rd Jul 2020, 9:24 am | #6 |
Dekatron
Join Date: Jul 2008
Location: Kington, Herefordshire, UK.
Posts: 3,670
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Re: Tape erasure - bulk
Bulk erasure is difficult to do manually - even with something like the WAL or the Leeraser, it is all too easy to induce LF disturbances (known as "bonks" in the day...) if the tape is anywhere near the field when the eraser is switched off. The non-latching switches on some erasers, whilst necessary for safety, make this more difficult as the operation has to be done one-handed. Weircliffes, on the other hand, were darned near perfect for the job - it was almost impossible to come out with anything less than a quietly erased tape. They are, however, bulky and heavy things.
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23rd Jul 2020, 9:48 am | #7 |
Hexode
Join Date: Jul 2009
Location: Wokingham, Berkshire, UK.
Posts: 437
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Re: Tape erasure - bulk
I tried with a colour tube degausser, the RBM disk type seemed to work reasonably well.
Usual practice, power off with DG about 1m away, power on, move slowly toward tape, hover close in circular motion, covering all tape for a few seconds then move away about 1m and power off. Didn't suffer any "bonks" ands far as I can tell it erased deep enough. Keep watches etc. away. Can only suggest you try it and see. John |
23rd Jul 2020, 11:08 am | #8 |
Pentode
Join Date: Feb 2020
Location: Waterlooville, Hampshire, UK.
Posts: 200
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Re: Tape erasure - bulk
There's a Weircliffe one here Hillmanie, lot 7075, any good?
https://www.twgaze.co.uk/auctions/ca...sion/?start=64
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23rd Jul 2020, 11:34 am | #9 |
Octode
Join Date: Dec 2017
Location: Morden, Surrey, UK.
Posts: 1,558
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Re: Tape erasure - bulk
Weircliffe were extremely good but king expensive - I bought one for a customer back in the late seventies and it was several hundre pounds even with trade discount.
If that one in the auction only makes top estimate the carriage will be more.... |
23rd Jul 2020, 12:07 pm | #10 |
Octode
Join Date: Jul 2006
Location: Perth, Western Australia
Posts: 1,969
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Re: Tape erasure - bulk
In our Talking Book production when we used analog tape, we used a large Garner eraser which used a small rubber conveyer belt. Very handy for erasing a large number of cassettes and letting the belt convey them into a large cardboard box ready to be loaded and rerecorded on the high speed duplicators.
The reason for the bulk erasing was that for the monthly talking newsletter we reused the cassettes for next month's newsletter issue, and because our Otari high speed duplicators had no ability to erase the cassettes. I used to service those HS duplicators and I used another smaller bulk eraser to erase the cassettes before making test recordings. I still have my small bulk eraser but these days I only use it to demagnetise metal tools used near tape heads and guides on machines. Pretty much every tape recorder automatically erases the old programme when making a new recording. I'm just curious why these days anyone would be needing a bulk tape eraser. It seems likely that these days the supply of used bulk erasers outstrips the demand and so prices shouldnt be too high. As Barry says the cost of carriage might be another matter. |
23rd Jul 2020, 12:12 pm | #11 |
Nonode
Join Date: Aug 2007
Location: South Bradford, West Yorkshire, UK.
Posts: 2,573
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Re: Tape erasure - bulk
Be careful when using a bulk eraser. The magnetic field can erase the magnetic strips on credit, debit etc cards. Guess how I found this out!
Keith |
23rd Jul 2020, 12:48 pm | #12 |
Pentode
Join Date: May 2019
Location: Galway, Republic of Ireland.
Posts: 208
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Re: Tape erasure - bulk
Awed again by the deluge of informed posts. Thanks all. The upshot is that I won't try anything DIY, rewinding transformers etc now beyond me. I'll check the auction house one of course and if not viable will sit on my oars further
TT |
23rd Jul 2020, 12:54 pm | #13 |
Dekatron
Join Date: Apr 2012
Location: Worksop, Nottinghamshire, UK.
Posts: 5,553
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Re: Tape erasure - bulk
If you can get hold of a big laminated choke there will be no rewinding involved.
You just do the lams and then test on a Variac to find out what voltage the core saturates at. Just into saturation is best. I did one using a coil from a large shaded pole motor and a set of lams that fitted it. It was a low voltage motor so the transformer voltage was selected accordingly. I have not used it for many years. |
23rd Jul 2020, 1:02 pm | #14 | |
Pentode
Join Date: May 2019
Location: Galway, Republic of Ireland.
Posts: 208
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Re: Tape erasure - bulk
Quote:
TT |
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23rd Jul 2020, 2:07 pm | #15 |
Hexode
Join Date: Dec 2018
Location: Sheffield, South Yorkshire, UK.
Posts: 364
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Re: Tape erasure - bulk
You could try a couple of decent sized magnets
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23rd Jul 2020, 2:23 pm | #16 |
Octode
Join Date: Jul 2006
Location: Perth, Western Australia
Posts: 1,969
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Re: Tape erasure - bulk
Again it depends on the purpose of the bulk erasure. If it's just to erase sensitive information on a lot of tapes, strong enough magnets will probably do it. Magnets erase tapes but leave the tape with a lot of background noise.
Professional bulk erasers like the Weircliffe and the Garner were designed to smoothly ramp the magnetic field down to zero, leaving the tape with as low noise as possible for that tape, even lower than possible on a new recording. I have some ex radio station tapes from the 50's and 60's and at the end of the programmes the tape reverts to a noisy background. The station's bulk eraser must have used magnets. Once at the talking book production facility, recordists complained that when they went into Record mode a brief but loud "bump" noise was recorded on the tape. The new blank tapes must have been passed through some sort of bulk eraser which left them polarised, leading to the bump noise when going into record. We fixed the problem by properly bulk erasing the entire stock of new tapes on the Garner eraser. |
23rd Jul 2020, 3:48 pm | #17 |
Moderator
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,876
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Re: Tape erasure - bulk
There is a post on this site "Dozens of Radios etc at Diss On-line Auction Mon 27th"
Lot 7075 is a weircliffe bulk eraser with a price estimate of £15-20 David
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24th Jul 2020, 7:54 am | #18 | |
Octode
Join Date: Mar 2006
Location: Lund, Sweden
Posts: 1,632
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Re: Tape erasure - bulk
Quote:
I've never tried erasing a tape with it as I always assumed that the field would be nowhere as powerful as needed to successfully erase magnetic tape (don't even think it contains an iron core, it's not heavy enough), but perhaps I should give it a go? |
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24th Jul 2020, 10:31 am | #19 |
Dekatron
Join Date: Apr 2012
Location: Worksop, Nottinghamshire, UK.
Posts: 5,553
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Re: Tape erasure - bulk
I can remember field engineer where I worked at the time telling me about the day when the tube degausser got flipped over so that the button was pressed.
It filled the workshop with smoke. |
24th Jul 2020, 11:28 am | #20 |
Octode
Join Date: Jul 2006
Location: Perth, Western Australia
Posts: 1,969
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Re: Tape erasure - bulk
Another thing to watch is that the high energy tapes require a much stronger magnetic field to erase them. My little old bulk eraser will fully erase older reel to reel and Type I cassette tapes but not Chrome cassettes let alone Metal. The same for VHS or Beta cassettes which are basically a Chrome tape. Later Video8/Hi 8/DV tapes etc use a Metal formulation which is hard to erase.
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