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'12C509-JW How long to erase?'
1998\11\01@014818 by James Cameron

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I've scanned the archives of the PICLIST (now that they have returned),
and seen a few opinions ... but how long should a 12C509-JW be exposed
to a UV eraser unit?  I haven't found any specification of the time in
the 12C509 data sheet.

--
James Cameron                                      (spam_OUTcameronTakeThisOuTspamstl.dec.com)

OpenVMS, Linux, Firewalls, Software Engineering, CGI, HTTP, X, C, FORTH,
COBOL, BASIC, DCL, csh, bash, ksh, sh, Electronics, Microcontrollers,
Disability Engineering, Netrek, Bicycles, Pedant, Farming, Home Control,
Remote Area Power, Greek Scholar, Tenor Vocalist, Church Sound, Husband.

"Specialisation is for insects." -- Robert Heinlein.

1998\11\01@104837 by Peter L. Peres

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On Sun, 1 Nov 1998, James Cameron wrote:

> I've scanned the archives of the PICLIST (now that they have returned),
> and seen a few opinions ... but how long should a 12C509-JW be exposed
> to a UV eraser unit?  I haven't found any specification of the time in
> the 12C509 data sheet.
'pends on the light. A 4-8W tube type lamp at 12 mm takes 30 minutes to
be sure (it's blank after 12-15 min but it's better to overdo it).

Peter

1998\11\01@194555 by James Cameron

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Peter L. Peres wrote:
>  'pends on the light. A 4-8W tube type lamp at 12 mm takes 30 minutes
> to be sure (it's blank after 12-15 min but it's better to overdo it).

Thanks Peter.

Anyone know where the specification from Microchip is for this?

The unit I have on loan is an 8W 253.7nm 6.4mW/cm2 "Ango", with a draw
just big enough to require 12C509-JW's to be dismounted from the machine
pin sockets I'd like to keep them in.  ;-}

My first go was five minutes, and it seemed blank afterwards.  I even
remembered to record the OSCCAL value.

--
James Cameron                                      (.....cameronKILLspamspam@spam@stl.dec.com)

OpenVMS, Linux, Firewalls, Software Engineering, CGI, HTTP, X, C, FORTH,
COBOL, BASIC, DCL, csh, bash, ksh, sh, Electronics, Microcontrollers,
Disability Engineering, Netrek, Bicycles, Pedant, Farming, Home Control,
Remote Area Power, Greek Scholar, Tenor Vocalist, Church Sound, Husband.

"Specialisation is for insects." -- Robert Heinlein.

1998\11\01@231620 by Matthew Ballinger

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It will very tremendously. With my eraser, the 16C71's erase in about 5 mins.
The eraser's lamp is about 1mm from the chip's window, therefore takes little
time. Your's maybe different. So just program one put it in the eraser and
erase check every 3 mins or so.

1998\11\03@062639 by Peter L. Peres

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On Mon, 2 Nov 1998, James Cameron wrote:

> Anyone know where the specification from Microchip is for this?

;)

> The unit I have on loan is an 8W 253.7nm 6.4mW/cm2 "Ango", with a draw
> just big enough to require 12C509-JW's to be dismounted from the machine
> pin sockets I'd like to keep them in.  ;-}

If you halve the distance the power grows fourfold (inverse square law).
Your distance is smaller than mine was (since the machined socket must be
removed - guess why I choose 12 mm above DIL chip?). Erasure power should
be written somewhere in the specs. Used to be with EPROMs.

> My first go was five minutes, and it seemed blank afterwards.  I even
> remembered to record the OSCCAL value.

See how long it takes by checking every minute and do it thereafter for
twice or thrice as long.

Peter

1998\11\03@105236 by Reginald Neale

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Peter Peres said:

(much snipped)

>If you halve the distance the power grows fourfold (inverse square law).
>Your distance is smaller than mine was (since the machined socket must be
>removed - guess why I choose 12 mm above DIL chip?). Erasure power should
>be written somewhere in the specs. Used to be with EPROMs.
>

Very minor quibble: The inverse square law holds only for a point source.
With a linear/area source and distances on the order of the chip itself,
improvements from moving the chip closer are not as large as the inverse
square law would predict.

Reg Neale

1998\11\03@142835 by Peter L. Peres

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On Tue, 3 Nov 1998, Reginald Neale wrote:

> Peter Peres said:
>
> (much snipped)
>
> >If you halve the distance the power grows fourfold (inverse square law).
> >Your distance is smaller than mine was (since the machined socket must be
> >removed - guess why I choose 12 mm above DIL chip?). Erasure power should
> >be written somewhere in the specs. Used to be with EPROMs.
> >
>
> Very minor quibble: The inverse square law holds only for a point source.
> With a linear/area source and distances on the order of the chip itself,
> improvements from moving the chip closer are not as large as the inverse
> square law would predict.

An even smaller quib: In the case of short wave UV air plays a major role,
as it absorbs UV at a respectable rate with volume. I have used a large UV
projector (high frequency point source bulb in metal reflector) and it
generates so much ozone in about 5 in of air to the target that you can't
work with it without exhaust. This is a 15 Watt input device.

Peter

1998\11\03@150745 by Brian Striggow

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Some pretty basic eprom erasure questions:

What is the effect of direct or indirect sunlight on eproms??

In the absence of a UV source, could direct sunlight be used to erase an
eprom??

1998\11\03@153645 by paulb

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Peter L. Peres wrote:

> An even smaller quib: In the case of short wave UV air plays a major
> role, as it absorbs UV at a respectable rate with volume.

 Thank goodness for that, or we humans would be moles and plants would
be a different ballgame.

Brian Striggow wrote:

> What is the effect of direct or indirect sunlight on eproms??

 Very little, but may prevent you reading from them while the light is
shining.

> In the absence of a UV source, could direct sunlight be used to erase
> an eprom??

 For the same reason as it is safe to be in the sun for up to 10
minutes a day (longer with hat, cloting and sunscreen), it is difficult
to erase an EPROM in the sun.  It is generally held to take several
weeks.

 OTOH, don't leave equipment with uncovered EPROMS out in the sun...

 Reminds me of my rules about not buying PIR sensors at garage sales
(on tables, out in the sun...)
--
 Cheers,
       Paul B.

1998\11\03@182232 by Tony Nixon

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Brian Striggow wrote:
>
> Some pretty basic eprom erasure questions:
>
> What is the effect of direct or indirect sunlight on eproms??
>
> In the absence of a UV source, could direct sunlight be used to erase an
> eprom??

When I first started messing around with EEPROM's all I had to erase
them was the sun. So, yes it does work, but you need a sunny day with no
clouds, and it will erase in a few hours. On cloudy days, forget it.

Maybe these days with smaller die sizes, it will take a lot longer.


--
Best regards

Tony

Multimedia 16F84 Beginners PIC Tools.

http://www.picnpoke.com
Email picnpokespamKILLspamcdi.com.au

1998\11\04@122408 by Peter L. Peres

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On Wed, 4 Nov 1998, Tony Nixon wrote:

> Brian Striggow wrote:
> >
> > Some pretty basic eprom erasure questions:
> >
> > What is the effect of direct or indirect sunlight on eproms??
> >
> > In the absence of a UV source, could direct sunlight be used to erase an
> > eprom??
>
> When I first started messing around with EEPROM's all I had to erase
> them was the sun. So, yes it does work, but you need a sunny day with no
> clouds, and it will erase in a few hours. On cloudy days, forget it.

Ouch ! That ozone hole must be really big. When was this ? It takes at
least 420 nm to start erasing and it takes less than that to start a skin
cancer.

Peter

1998\11\04@152229 by Gavin Jackson

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part 0 916 bytes
-----Original Message-----
From:   Peter L. Peres [SMTP:.....plpKILLspamspam.....ACTCOM.CO.IL]
Sent:   Thursday, 05, November, 1998 07:27 AM
To:     EraseMEPICLISTspam_OUTspamTakeThisOuTMITVMA.MIT.EDU
Subject:        Re: 12C509-JW How long to erase?

On Wed, 4 Nov 1998, Tony Nixon wrote:

{Quote hidden}

Ouch ! That ozone hole must be really big. When was this ? It takes at
least 420 nm to start erasing and it takes less than that to start a skin
cancer.

Peter

1998\11\05@165148 by Tony Nixon

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Peter L. Peres wrote:
> Ouch ! That ozone hole must be really big. When was this ? It takes at
> least 420 nm to start erasing and it takes less than that to start a skin
> cancer.

About 5 years ago when I was using 2764 EPROMS with the old 6502. I just
put them outside facing the sun on a window sill.


Gavin Jackson wrote:
>
> How did you erase an EEPROM with sunlight? :-)
I put it under a magnifying glass ;-)

--
Best regards

Tony

Multimedia 16F84 Beginners PIC Tools.

http://www.picnpoke.com
Email picnpokespamspam_OUTcdi.com.au

1998\11\20@070852 by Tony Nixon

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Peter L. Peres wrote:
> Ouch ! That ozone hole must be really big. When was this ? It takes at
> least 420 nm to start erasing and it takes less than that to start a skin
> cancer.

About 5 years ago when I was using 2764 EPROMS with the old 6502. I just
put them outside facing the sun on a window sill.


Gavin Jackson wrote:
>
> How did you erase an EEPROM with sunlight? :-)
I put it under a magnifying glass ;-)

--
Best regards

Tony

Multimedia 16F84 Beginners PIC Tools.

http://www.picnpoke.com
Email @spam@picnpokeKILLspamspamcdi.com.au

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