Debbie, you didn't say you were going to pulse-modulate IR leds as
illumination. If its for a camera, it might be OFF when the camera needs
illumination. You need to simply turn ON the IR during the camera exposure,
about 50mS, then turn it off.

--Bob


At 12:46 PM 7/15/2003 +1000, you wrote:
>PICers - i b'boarded that ir pulser using a cap-coupled MTP3055
>mosfet.everything works fine  - i'm really driving a poor ol'red led with 12V
>thru a 5R6 resistor. Hah, it turns orange at that current level. :) On time is
>about 8 msec, OFF time is about 90 something msec - so it has a rather
>annoying
>flicker.
>
>The diode is flashing brightly that's 4 sure but it doesn't seem,
>subjectively,
>to be giving out all that much extra light. just looking at it anyway. Has
>anyone acually done this? I read that LEDs pulsed at high current give out
>enough light to double as a sort of spotlight for photographic purposes. Hmmm,
>but now i see one in action - does it really work? if u pulsed a bunch of IR
>leds would they give out enough IR to make a difference in the dark to a
>CCD/CMOS sensor?
>
>Thankz 4 all the input on this one!
>
>Debbie :)
>
>  --- Mike Harrison <mike@WHITEWING.CO.UK> wrote: > On Sun, 13 Jul 2003
> 08:24:13
> >
> >                                       |                          |
> >                                       +--LED--LED--LED--LED--Rs--+
> >                                       |                          |
> >                                   d|--+-LED--LED--LED--LED--Rs---+---R2---
> > +12V
> >                                    |                             |
> > Pic output --100R---C1---+----+----| N-Ch logic-level Mosfet     |
> >                          |    |    |                             |
> >                          |    |   s|-+                           C2
> >                          R1   D      |                           |
> >                          |    |      |                           |
> >            --------------+----+------+---------------------------+--0V
> >
>
>
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