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Posted by Peter Harrison on June 16, 2008, 2:33 pm
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garethrichardadams@hotmail.com wrote:
> Hi all,
>
> I know this has been covered before and the conclusion was to use a
> sharp IR sensor...but! I don't need an accurate distance, I just want
> a relative distance - moving closer, moving further away...
>
> I've found this circuit which is supposedly for the Roland D-Beam
> controller (a controller on a musical keyboard that senses the
> distance to your hand and adjusts something accordingly).
> http://members.tripod.com/urekarm/synth/maebd.pdf
>
> It appears to just use an ir led and phototransistor. Is the rest of
> the circuit just the correct band pass filter?
>
> Are there any other circuits out there similar to this?
>
> Thanks
>
> Gareth
Over what physical range would you want this to work?
How small a target do you want to detect?
What are the ambient lighting conditions going to be like?
The Roland circuit has the detector AC coupled so that, within some
limits, ambient lighting will not affect the output too much.
Presumably, there is some kind of amplitude detector after that.
My micromouse sensors work over a range of 3cm to 15cm or so and could
be used at different ranges with care. They are very simple.
Try here for a start:
http://www.micromouseonline.com/content/view/60/58/
Pete Harrison
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>
> I know this has been covered before and the conclusion was to use a
> sharp IR sensor...but! I don't need an accurate distance, I just want
> a relative distance - moving closer, moving further away...
>
> I've found this circuit which is supposedly for the Roland D-Beam
> controller (a controller on a musical keyboard that senses the
> distance to your hand and adjusts something accordingly).
> http://members.tripod.com/urekarm/synth/maebd.pdf
>
> It appears to just use an ir led and phototransistor. Is the rest of
> the circuit just the correct band pass filter?
>
> Are there any other circuits out there similar to this?
>
> Thanks
>
> Gareth