photoresistors as encoders

Sticky

Hi

I am trying to use a combination of led and photoresistor to detect rotations of a motor. I am using the rctime command but I get different readings during the day and at night due to ambient light I would guess. I am just wondering if it would be easier to use the device as a straight digital device rather than a sort of analog one. Any suggestions?

Zoot

Yes, you want "digital".

But I think that an LED and photoresistor is not a good combination for an encoder; generally IR and an IR photodiode or IR phototransistor make for a better encoder "reader" as the response time is very fast and you won't have so many problems with ambient (visible) light.

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When the going gets weird, the weird turn pro. -- HST

1uffakind.com/robots/povBitMapBuilder.php
1uffakind.com/robots/resistorLadder.php

Sticky

Thanks Zoot makes good sense.

Zoot

e.g.

http://forums.parallax.com/showthread.php?p=772850

http://forums.parallax.com/showthread.php?p=719074

search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=QRD1114-ND

www.acroname.com/robotics/parts/R64-P5587.html

If memory serves, erco had a supplier with a much better price on the Hamamatsus, but can't seem to put my finger on it. But even at $5 the performance can be well worth it (they work in all kinds of adverse conditions, even with dirty encoder discs with narrow stripes, etc.).

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
When the going gets weird, the weird turn pro. -- HST

1uffakind.com/robots/povBitMapBuilder.php
1uffakind.com/robots/resistorLadder.php