Light Photo-sensor Timer Help Please!

[Madii]

I am supposed to design a light photo-sensor velocity counter. The circuit is supposed to be in this way that two light photo sensors are fitted at the beginning and at the end of a cardboard and in direct contact with lasers.

When any object in motion is rolled across, for example a ball, when the first laser and photo sensor connection is disrupted, a trigger is generated which activates a digital timer, and continues timing until the ball disrupts the second laser photo-sensor connection and stops the clock.

The problem I'm having is with the trigger, how do I set it up in such a way that it starts timing at the first disruption and ends timing at the second disruption? Will a J-K latch work?

 

[(*steve*)]

A JK latch might work. The other way is to independently time both events and then look for the difference between them. How you do it depends on the equipment you have.

If you have something that can count while a logic level is high (or similar) then your idea may be viable.

 

[Madii]

A JK latch might work. The other way is to independently time both events and then look for the difference between them. How you do it depends on the equipment you have.

If you have something that can count while a logic level is high (or similar) then your idea may be viable.

Thank you so much, I'll definitely try out

 

[foTONICS]

i agree with steve about the JK flip flop but i would keep it at one JK depending on how accurate you are reading. difference between devices and all

 

[formach]

hello...im doing the same project as u...
so can u help me with this
i plan to use microcontroller,photoelectric sensor and display through LCD display...
the circuit for photoelectric sensor give me problem..
any advice?

 

[wingnut]

Hi

In the "Time trial..." thread under "microprocessors and Programming, in post #5 I described how I got this exact project to work on the Arduino. I just used two CdS photoresistors.

 

[CDRIVE]

It doesn't take a psychic to know this is a class assignment. No one will be doing either of you a service if they do any more than guide you guys.

Chris

 

[foTONICS]

It doesn't take a psychic to know this is a class assignment. No one will be doing either of you a service if they do any more than guide you guys.

Chris

i work for my school helping students troubleshoot labs, give advice, and test and repair lab equipment. Now that you mention it this is exactly what these guys are doing. I get these same type of questions all the time, especially when the mention of microprocessors and LCD screens. It's surprising how many students dive into a project like this with out having anyone in their group that can program. The number one thing overlooked in final projects is the programming side of things

 

[(*steve*)]

The number one thing overlooked in final projects is the programming side of things

I guess the one thing that comes from age and experience is that you should play on your strengths and not on your weaknesses.

 

[CocaCola]

The number one thing overlooked in final projects is the programming side of things

That's because, Joe's friends, neighbors, boyfriends, cousins, dogs, relative, mothers, girlfriend said you can do anythign with one of those there Arduinos... And John says he heard on the Internet that you just need to plug it into one of those Ardunio things and load in the code and it works, and people give the codes away... While Jack interrupts that he heard the same about those PIC chips, just load the codes that you can find on the Internet and it will do anything you need...

So now Joe, John and Jack have it all figured out, they just need one of those things that does it all. and a few other do-dads with the free codes that is to be found on the Internet...

In the end IF you have the programming skills a project like this is stupid easy with a micro, but that assumes you have the necessary skills or are willing to learn them... And by learn I don't mean 'asking' someone to provide you the answers or hand it to you on a silver platter... I mean sitting down and spending the next few weeks as a group in a crash coarse on programming... At that point everyone in the group would be able to provide valid input...

 

[foTONICS]

My favorite one was a group of students that tried to send messages Wirelessly between LCD's. They procured some code from somewhere, copy+paste into MS word, then copy+paste into the IDE then were dumbfounded when nothing worked. To keep this explanation short just imagine all the autocorrect and capitolizing that WORD did. (not to mention the fact that no where in the code was anything ever told to write to the LCD)

 

[foTONICS]

And this was all discovered 3 days before the project due date