I am planning to use this sensor ( link attached ) and would like to hear from somebody's experience how fast does this sensor reacts when an object appears in the preset threshold distance.
I do not have one to check ( on order) that myself and did not glean such data from the spec.
I am going to use this sensor as a remote / reflective optical encoder / counter.
Thanks for your help.
Cheers Vaclav
It really depends on how fast is fast?
It has what seems a pretty standard (= 'relatively' slow) photo transistor in the package. However the rise/fall times are not mentioned in the data sheet. So my guess would be from 10 to 50 uSecs for rise/fall times. It is possible to get faster photo transistors with nSec rise/fall times, if needed.
Of bigger concern is that the typical range used in the data sheet seems to be <15mm. I was playing around with some of these last week, and if I remember correctly it was responsive up to 5-10+ cm using max rated current through the emitter - depending on the surface of the object.
Sorry, I couldnt be more exact, but speed was not one of the issues in my testing.
Thanks, that info does help. I can code in us range to start and than adjust it later.
I was just hoping it is not in ms range.
I see there are at least two different types - open 5 mm LED or a slotted IR sensor. I suppose the slotted one would be more "direct" that the open LED type.
Since they both are "object detectors " and not really intended as remote optical counter one has to play with it to really know.
Thanks
Vaclav
Hi,
All the info you need is on the Vishay data sheet!! I have just used 4 of these TCRT5000L to make my line follower with two close together in the centre, the outer two will be edge detectors. The TCRT5000L has 15mm leads, useful at times. As for speed can't say but it will be fast enought for what you need, I'm sure.... Not fitted my unit yet as I only made the PCB yesterday, but early test seem to prove it works fine.
The slotted type would work but needs a slotted disk to read, this is usually fixed to the wheel axal. Also the Vishay TCRT1000 works well as a rev counter, very useful if you need to read 90 Deg from the PCB.
Visit the Vishay website for a copy of the datasheet!
Hope it helps, here's a picture.
Regards
Mel.
Mel, to be honest, you did not add anything new.
If you read the OP , been there, done that. There is no spec covering hysteresis / response speed.
Thanks anyway.
Cheers Vaclav
Hi Vaclav,
Perhaps you should give us a better idea of just what it is your aiming at! Unless your talking really high speed then you could be over thinking the idea? When I was searching the forum for ideas, I did find a bit of code for a rev-counter using a similar device and a ISR that counted into the 1000's per minute. As AnalysIR says what is fast!!
Just wait untill they turn up and have a play with them, those modules usually use an LM393 comparator to give you a nice clean output, but that will add a slight delay too, that is on the data sheet at 1.4uS.
But more info please.
Regards
Mel.