IR Distance Sensor

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
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snipped-for-privacy@hotmail.com wrote:

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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Ideally, the range would be about 5 - 30 cm.
The target will be a hand.
Ambient light conditions will be indoors, but could be flourescent light
They look like they might do the job - thanks!
Gareth
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