Hi nettron1000,
Yes they look just like the little units in the toy i have.
Even the batteries look the same.
I don't have a digicam, else i would send a pic, this one is
shaped like a plastic mouse, its a toy for a cat.
I was thinking of driving the unit with pulses, on for a
short time and off for about ten times as long.
Maybe at about 450Kc/s, i think thats typical I.F. frequency,
i should be able to use a row of I.F.s out of a small pocket
radio to pick out the signal.
Maybe that degree of sensitivity wont be needed, i dunno.
Maybe the majority of its life expectancy is used up in the
start up of the laser ? Maybe under running could shorten its
life ?
If they sell replacement heads as part of the package, should
that tell me something ? Maybe they fail often? or unexpectedly?
I don't know what to do for the best.
So i am going to run this at about 3 volts, which is a bit lower
than the three cells at 4.2 volts roughly, and i am going to see
if i need to modulate it.
Its intended to be run from inside inside the house, out through
a window, and to travel round the perimeter using three or four
mirrors back to a receiver, probably at the start point.
As you say the beam carries well, with not much attenuation for a
good distance, but i expect some deterioration from the mirrors.
It may also be possible to detect the presence of the beam, if
modulated, on the mirror surface with a sensor placed closely.
That way, an interruption could be tied to a particular section
of beam. This occurred to me after playing around with it, i
noticed that when it was aimed at a mirror, the beam did reflect
quite happily to the place the mirror put it, i noticed that
the spot from the beam was also clearly visible on the surface
of the mirror !
This obviously uses some of the strength from the beam, i assume
its just surface imperfections on the glass.
But whatever the reason, it might be possible to detect it with
a sensor placed closely to the spot on the mirror. That would give
me an indication of which section of beam was interrupted.
It may or may not need the extra gain of an I.F. strip, i don't
know yet, i have some experimenting to do !
Any suggestions you may have would be welcome,
Cheers, John
Just for you, heres a little 'aide memoir' to spell believe,
***
never
believe
a lie
***
Cheers, John