Re: After IR beam break info

[Justin <justin@xxxxxxx>]

Thanks, Ian.

An 'off the shelf' jobbie is looking like a good idea at this point! I see
Quasar Electronics have a beam break with a claimed range of 25m, so I
would
hope 5m is achievable outside. I have read that exposed film is a good
filter
so I hope that some of that and a tube will help.

Looking at the parts list for the Quasar unit, I doubt I could build it for
less than the price of the kit (the amplified IR receiver is £5+ at
Farnell!),
so I think I'll order one up.

The Xantech receiver has since gone to HA heaven, but thanks for the offer.


Justin.

Quoting ian.bird@xxxxxxx:

> Hi Justin
>
> As far as I know the following is good advice (but I stand to be
> corrected)
>
> There is a lot or IR pollution outside in particular from the sun but
most
> of the time from other sources too. Assuming you only want to detect a
> beam being broken you will need a very directional IR transmitter, a
> receiver that ideally can be built into a tube which will provide some
> form of protection from stray IR etc. and a modulated beam so you can
tell
> the difference between stray IR and the stuff from your transmitter.
>
> I think the Maplin units will do most of this at a tenner but I cannot
> vouch for the range. If you are building your own then you will need
to
> send the modulated signal and detect and check it at the receiver. I
would
> guess your current experiment is running into problems with the
strength
> of the output from the photo diode as over a range this will be rather
> small.
>
> Drop me a line if you want the circuit diagram for the Maplin units as
it
> on the back of the pack for the units and I have one at home.
>
> See ya
>
> Ian
>
> p.s. if you still have that Xantech IR receiver I can now solder the
> transistors that were on it - you know, the tiny black three legged
things
> that melted on us.