Re: Clearing EPROMs: How much time to lay in the sun?

From: Gabriele Bozzi (
Date: 2006-07-16 22:42:15

Indeed Rainer I experimented the "memory effect" you mention but to  
avoid to erase forever the eprom I always stayed on the safe side and  
preferred two short exposures in place of a long one, after all I am  
an occasional user of  these things and have no reference for the  
chips sometimes I gather around.

What I am not really sure, but I assume you know what you say since  
you say you did it, is the UVA lamp thing... Of course such a source  
will push some radiation in the range of 2500 and something angstrom  
but you risk to melt the chip with the rest of the spectrum!!

Also acquarium lamps could do, they emit on the right range.

As for my calculation: I did not expect to be right at the first  
attempt. Just the order of magnitude :-)

Anyway, since the weather seems to be quite sunny, I will leave a  
2764 (not risking too much eh) in the garden and inform this list on  
regular basis what is the outcome....


On 16 Jul 2006, at 21:21, Rainer Buchty wrote:

>> - A mid-summer Northern emisphere location at Sea level, 60%  
>> humidity,
>>   sunny exposure (75% of total sunlight):  ~ 15 days
> I doubt that the EPROM is *really* erased after that period.
> Have a look at this:
> (Explanations in German, but Babelfish should do a somewhat good  
> job on
> it.)
> Apart from the erase patterns (see animated GIFs), the really
> interesting part is that even when using an EPROM eraser until the  
> is erased (3 minutes worst) data comes back when you lower the supply
> voltage from 5V to 3V.
> To surely erase an EPROM it takes 10 minutes.
> Rainer
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