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rohitd
12-18-2009, 05:31 PM
Hi,
sorry for creating a new thread again, I added the same query to one of the older threads, but was unable to see the topic in active topics so i am adding it here again :? .

I have a query related to generating a speed encoder. I read the thread for making speed encoder. I wanted to create a speed sensor which sense speed by detecting black dots on a wheel.

i was refering following link :
http://www.geology.smu.edu/~dpa-www/robo/Encoder/pitt_html/encoders.html

it explains the encoder creation using Hamamatsu 5587 photo reflector sensor(cost 3.5$ each). I visited the Hamamatsu web site and came to know that the chip is obsolete.

Can you please specify the chip number and circuit diagram if any.
I want to measure speed of motor max speed is 100Hz

Thanks in advance

Best regards
Rohit

asimov_18
12-18-2009, 11:39 PM
one can find such reflective type senror arrary in any servo tape mechanism.use any old music deck with feather touch buttons for operation(soft electronic controls) else use simple IR Led and IR photodiode. in case no money for that buy any old ball computer mouse and use sensor and ir led from that

Asimov

rao
12-19-2009, 07:51 PM
I would do what Asimov suggested and stick to a basic IR LED - Photodiode pair...hook it to a comparator and get pulses, and then read those pulses for frequency. But then everything depends on the motor speed, if you have high speed motor (which is highly unlikely for a robotics project) then you have to take in the latency of the comparator chip and detection speed of the photodiode as well..