Author Topic: Is this real UV?  (Read 8936 times)

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Offline ali6x944

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Is this real UV?
« on: August 04, 2016, 12:00:18 pm »
Hi everyone,
I was searching about a homebrew way to make uv light of enough concentration to erase a UV eprom and I found this:
https://youtu.be/Rq94tgZOEWw
Is this real uv light and if so could it erase the uv eprom?
 

Offline mikeselectricstuff

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Re: Is this real UV?
« Reply #1 on: August 04, 2016, 12:12:27 pm »
No, it's just filtering out the longer wavelengths, most of what comes out will be the blue LED wavelength
For EPROMs you need a specific wavelength of shortwave UV.
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Offline bktemp

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Re: Is this real UV?
« Reply #2 on: August 04, 2016, 12:15:14 pm »
For EPROM erasing you need UV-C (200-280nm). Typical LEDs are not able to generate UV-C, so no, it does not work for EPROM erasing.
 
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Online Ian.M

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Re: Is this real UV?
« Reply #3 on: August 04, 2016, 12:16:45 pm »
Not only NO, hell NO.

The cheapest way to do it is a 4W T5 germicidal UV-C tube in a 4W fluorescent torch in a light-tight box. UV-C light is an eye hazard so make sure you cant see the light or any reflections with the original torch tube in before fitting the UV tube.  The EPROM windows should typically be between 1/2 and 1 diameter from the tube surface.

You might be able to home-brew something with a carbon arc driven from an arc welder, but you'd need a fused quartz window, possibly a dichroic reflector to separate the IR and have massive amounts of waste heat to dissipate and would need to actively cool the EPROM.
« Last Edit: June 12, 2019, 01:31:14 pm by Ian.M »
 
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Offline ali6x944

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Re: Is this real UV?
« Reply #4 on: August 04, 2016, 02:52:05 pm »
Is it possible to erase uv eproms using concentrated sun light? Say with a magnifying glass?
 

Offline bktemp

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Re: Is this real UV?
« Reply #5 on: August 04, 2016, 03:05:18 pm »
If you use a lens for focusing sunlight into an EPROM, you will probably burn the EPROM instead of erasing the data because of the heat.
Another problem is, UV-C gets blocked by normal glass, therefore you need quartz glass for the UV-C light and an IR blocking filter for reducing the heating.

I haven't tried it, but it should be possible to erase an EPROM if it is exposed to sunlight for several weeks without any filters.
« Last Edit: August 04, 2016, 03:08:48 pm by bktemp »
 
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Offline AndyC_772

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Re: Is this real UV?
« Reply #6 on: August 04, 2016, 03:58:47 pm »
I have. If I recall correctly, not a single bit had been erased.
 
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Offline CatalinaWOW

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Re: Is this real UV?
« Reply #7 on: August 04, 2016, 04:42:46 pm »
I have also tried sunlight erasure of PROMS.  These were first generation PROMS so they had large design margins on the the well size and it was in the LA basin during the some of the worst smog years so it may not reflect results with newer PROMs or in a clear high altitude area, but two months exposure resulted in no loss of data.
 
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Online Kleinstein

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Re: Is this real UV?
« Reply #8 on: August 04, 2016, 04:53:50 pm »
In the old days, when EPROMs were used, I used an UV arc lamp, made for "medical" purpose. It needed quite some power, but was reasonable fast (e.g. less than 20 minutes).
 
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Offline CJay

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Re: Is this real UV?
« Reply #9 on: August 04, 2016, 04:54:46 pm »
Not only NO, hell NO.

The cheapest way to do it is a 4W T5 germicidal UV-C tube in a 4W fluorescent torch in a light-tight box. UV-C light is an eye hazard so make sure you cant see the light or any reflections with the original torch tube in before fitting the UV tube.  The EPROM windows should typically be between 1/2 and 1 diameter from the tube surface.

Definitely that. Works perfectly, or if you can locate one of the ancient 'health lamps' that had those tubes too
 
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Offline ali6x944

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Re: Is this real UV?
« Reply #10 on: August 05, 2016, 03:54:58 pm »
Do Xeon flash light have a potential to erase the uv eproms?
 

Online Ian.M

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Re: Is this real UV?
« Reply #11 on: August 05, 2016, 04:14:43 pm »
No.  Xeon photographic and stroboscopic flash tubes generally have borosilicate glass envelopes which block UV-C and may even have extra near UV filtering to avoid confusing the camera's Lux sensor and strange colour casts on the film or image.
See http://www.hakuto.com.tw/tw/dowfile.php?p=46
 
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Online edavid

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Re: Is this real UV?
« Reply #12 on: August 05, 2016, 04:24:36 pm »
No.  Xeon photographic and stroboscopic flash tubes generally have borosilicate glass envelopes which block UV-C and may even have extra near UV filtering to avoid confusing the camera's Lux sensor and strange colour casts on the film or image.
See http://www.hakuto.com.tw/tw/dowfile.php?p=46

There have been some commercial EPROM erasers that used Xenon tubes, see: http://www.grifo.com/PROG/uk_Eraser.htm

I guess they used special quartz tubes.

You can still buy replacements if you want to experiment:  http://www.dataman.com/erasers/strobe-bulb.html
« Last Edit: August 05, 2016, 08:27:34 pm by edavid »
 
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Offline timb

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Re: Is this real UV?
« Reply #13 on: August 05, 2016, 08:19:25 pm »
Do Xeon flash light have a potential to erase the uv eproms?

No, and it would require hundreds of flashes even if it did. EPROMs require minutes of UV to fully erase.

Just buy a cheap UV eraser from eBay. They're cheaply made and use an appliance timer, but they work and cost <$15!
Any sufficiently advanced technology is indistinguishable from magic; e.g., Cheez Whiz, Hot Dogs and RF.
 
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Online BU508A

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Re: Is this real UV?
« Reply #14 on: August 05, 2016, 09:00:23 pm »
Hi,

Hi everyone,
I was searching about a homebrew way to make uv light of enough concentration to erase a UV eprom and I found this:
https://youtu.be/Rq94tgZOEWw
Is this real uv light and if so could it erase the uv eprom?

No, this is rubbish.

Here you can find some UV LEDs with wavelengths of about 265nm and 280nm which should do the job. One LED should be sufficient.
But be careful, this kind of UV radiation is dangerous, so a proper shielding of the radiation is a must!

http://www.epigap-optronic.de/led.html (sorry, website is in German but I think you'll get the idea. Or google translate  ;) )

I do also recommend a constant current source for the LED to make sure, that it is working in it's specs.
These LEDs are not really cheap things, so 10 - 50 Dollars per piece (there are some which costs much more) is not uncommon.

Suggestion for a constant current source:
https://www.mikrocontroller.net/wikifiles/2/28/Ksq.png

HTH,

Andreas
“Chaos is found in greatest abundance wherever order is being sought. It always defeats order, because it is better organized.”            - Terry Pratchett -
 
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Online Paul Moir

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Re: Is this real UV?
« Reply #15 on: August 05, 2016, 10:56:02 pm »
Do Xeon flash light have a potential to erase the uv eproms?

No, and it would require hundreds of flashes even if it did. EPROMs require minutes of UV to fully erase.

Just buy a cheap UV eraser from eBay. They're cheaply made and use an appliance timer, but they work and cost <$15!

I actually have done just this with a regular "strobe" xenon flash.  It was the only thing I had at the time (and no money) so I built a little flasher for it.  It worked just fine, but it took days depending on the particular EPROM.

Nowadays I'm up to my armpits in UV-C bulbs.  They're used for water sterilization, air sterilization in building's ventilation and hospitals.  If you know anyone in those areas see if they have some old bulbs for you:  they're often replaced on a schedule.
 
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Offline crazyguy

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Re: Is this real UV?
« Reply #16 on: August 06, 2016, 08:32:45 am »
Is it possible to erase uv eproms using concentrated sun light? Say with a magnifying glass?

It is just a question of UV intensity and exposure time

Yes, according to ST M27256 datasheet, you can easure the eprom using sun light
http://www.futurlec.com/Memory/27256_Datasheet.shtml

ERASURE OPERATION (applies to UV EPROM) The erasure characteristic of the M27256 is such
that erasure begins when the cells are exposed to light with wavelengths shorter than approximately
4000 Å
. It should be noted that sunlight and some type of fluorescent lamps have wavelengths in the
3000-4000 Å range. Research shows that constant exposure to room level fluorescent lighting could
erase a typical M27256 in about 3 years, while it would take approximately 1 week to cause erasure
when exposed to direct sunlight
. If the M27256 is to be exposed to these types of lighting conditions
for extended periods of time, it is suggested that opaque lables be put over the M27256 window to
prevent unintentional erasure. The recommended erasure procedure for the M27256 is exposure to
short wave ultraviolet light which has wavelength 2537 Å. The integrated dose (i.e. UV intensity x
exposure time) for erasure should be a minimum of 15 W-sec/cm2
. The erasure time with this dosage
is approximately 15 to 20 minutes using an ultraviolet lamp with 12000 mW/cm2 power rating
. The
M27256 should be placed within 2.5cm (1 inch) of the lamp tubes during the erasure
. Some lamps
have a filter on their tubes which should be removed before erasure.

typical white  LED spectrum

https://en.wikipedia.org/wiki/Light-emitting_diode

The white LED strongest peak is at about 465nm, the intensity below 400nm is quite weak

 
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Offline Zero999

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Re: Is this real UV?
« Reply #17 on: August 06, 2016, 12:12:25 pm »
typical white  LED spectrum

https://en.wikipedia.org/wiki/Light-emitting_diode

The white LED strongest peak is at about 465nm, the intensity below 400nm is quite weak
Yes, most of the fluorescent effect was probably due to visible violet, rather than UV.

Another possibility is the LED used in the phone had a violet LED to excite the phosphor, rather than blue, as it gives a better white, and will give more UV, than a blue LED.
 
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Offline ali6x944

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Re: Is this real UV?
« Reply #18 on: August 12, 2016, 09:50:14 pm »
Thanks for all the help and thanks for clearing this for me...
You are the best ! :)
 


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