Chinese UV Eraser Lifespan

[vlad01]

405nm is typical for LEDs, lamps are normally wider band of UV but also give out shorter wavelengths than LEDs, shortwave lamps are in the 200s range of nm wavelengths.

some info here.

http://en.wikipedia.org/wiki/Ultraviole ... olet_lamps

[The1]

Doesn't look like it's the right wavelength, need around 250nm
http://en.wikipedia.org/wiki/EPROM

The recommended erasure procedure is exposure to UV light at 253.7 nm of at least 15 W-sec/cm² for 20 to 30 minutes, with the lamp at a distance of about 2.5 cm.

That cheap UV eraser in this thread nearly had it sitting on the window and probably a bit higher power hence you only need 5-10min to clear them.

[delcowizzid]

yeah mine near touch the tube and ive never needed more than 6 minutes.too long kills eproms

[immortality]

I've found different eproms require different amounts of time.

My old VN ones only took about 6-7 minutes but when I started playing with the VS they took double the time.

My timer is a bit dodgy too so I just use the clock to work out how long it's been on.

[vlad01]

I would take a guess that the VN ones being much older from the time they were first programed have already leaked a lot of their electrons on the floating gate, thus requiring less time to discharge when UV light is applied?

[vlad01]

oh and this too I found in wiki.

"EPROMs had a limited but large number of erase cycles; the silicon dioxide around the gates would accumulate damage from each cycle, making the chip unreliable after several thousand cycles. EPROM programming is slow compared to other forms of memory. Because higher-density parts have little exposed oxide between the layers of interconnects and gate, ultraviolet erasing becomes less practical for very large memories. Even dust inside the package can prevent some cells from being erased"

[The1]

ive found some now prob due to the age just wont hold after reprogramming, you do a read and compair and it just wont burn properly. I just use my newer memcals now with eeprom on them, if it's the older type i solder in a eeprom where possible.

[antus]

yeah mines in hours or something too, i use a stopwatch. Its about 3 years old, but wouldnt have erased more than about 10 memcals and still works, as far as I know - i havnt used it for quite some time now.