On Tue, 6 Feb 2001 12:11:29 +1100, you wrote:

>Bob Ammerman wrote:
>>
>> Roman,
>>
>> You've got the right idea of doing your development on the 16F84 (or =
even
>> better an 16F87x with ICD, but I digress).
>>
>> On my first 12C project I did just this -- started with MPSIM, then a =
16F84,
>> and by the time I burned the 12C it was _perfect_ the first time.
>>
>> I'm afraid you're gonna just have to buy a few JW's and an eraser (a =
1KW
>> tanning bed is probably the wrong intensitity and wavelength, and a =
small
>> 'pocket' eraser will pay for itself in reduced power consumption and
>> convenience very quickly.
>
>
>Thanks Bob, any sources for a cheap eraser? I
>can build one if the light source is not critical.
>And how long do they take to erase normally?
You need a germicidal lamp, not a 'black light' or insect zapper tube.
The most common ones look like normal slimline (4/6/8 watt 6,9,12" I
think ) fluorescent tubes, but they are transparent (no phosphor), and
can be driven with the same type of ballast. You MUST use a
light-proof enclosure with an interlock as the UV can cause eye and
skin damage. Erase times are typically 5-10 mins.
Another type of bulb (don't know if it's still made) is the Philips
TUV, which needs no ballast. =20
The easiest (but probably not cheapest) source is often as 'spares'
for commercial UV erasers.

>Last question (I promise!) if using the internal
>4MHz osc on the OTP parts, does it need calibrating
>or what range freq are they in?
There is a calibration value programmed into OTP parts, which you need
to load into the OSCCAL reg by putting MOVWF OSCCAL at address 0.=20
This brings the osc to within about 5% of 4MHz (check datasheet for
tolerance)

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