How can I add an indicator light to my OPB745 sensor?

[oslaught]

Hi all,

i got e above mention sensor for my mini project. encounter a problem is that the sensor does not have an indicating light that show if the sensor is activated.
i've measure between the GND and the signal output which gives a 4.8V when nothing is sense. when there's object infront, the voltage will drop to ~2.2V. I've try connecting a 5V led between it, but does not work as the output signal doesn't give a pure GND.

like to know if there's anyway i can connect the led as a indicator for the sensor. maybe a circuit?

thank you all.

 

[berkeman]

Welcome to the PF. It helps us to help you if you provide a link to the datasheet for the part that you are asking about. I used google and then Mouser to get this one:

http://www.optekinc.com/pdf/OPB745.pdf

You need to buffer the output of this reflective photosensor in order to drive an LED reliably. Just put a comparator at the output of the Darlington phototransistor, and drive the LED with the output of the comparator. Be sure to design your comparator circuit with good margin on the trip levels, and with positive feedback to provide hysteresis.

 

[oslaught]

Welcome to the PF. It helps us to help you if you provide a link to the datasheet for the part that you are asking about. I used google and then Mouser to get this one:

http://www.optekinc.com/pdf/OPB745.pdf

You need to buffer the output of this reflective photosensor in order to drive an LED reliably. Just put a comparator at the output of the Darlington phototransistor, and drive the LED with the output of the comparator. Be sure to design your comparator circuit with good margin on the trip levels, and with positive feedback to provide hysteresis.

Hi berkeman. thanks for finding the link. yup, that's the sensor.
I'm more of a electrical guy, not so into electronic. Possible to explain more on what/how to make it works. meanwhile I'll ask my friend about it too.
Thanks a lot..