First of all, I have to say that despite I’m kind of „tech guy“, I’m absolute noob with all the Arduino stuff and I have never made an electric circuit more complex than few led diodes with resistor and switch...
BUT I fell in love with the device and I’m determinded to learn some basics and experiment.
The first „gadget“ I need (not only want) to build is a kind of time-measuring–thing, triggered and stopped by breaking a laser beam. Then show the time on display, keep it there a few seconds and then automacially reset and wait for another masurement. It is needed to be all powered by ordinary battery format which is easily bought and replaced.
The gate should be able to measure passage of a car, so one side will be the whole system, the other side just a mirror or something to bounce off the beam.
Is it going to work? Are those components compatible? Is there something missing? Am I able to make this work with some tutorials and maybe little advice from this forum?
Be warned: directing the narrow laser beam onto any receiver is very delicate. You may use a special (cat eyes) reflector for less sensitive adjustment of the mirror (untested).
Why do people always think "laser".
A common IR diode as used in a remote control and a remote control receiver might be easier.
What distance are we talking about.
Leo..
An IR control has a wide beam, which is reflected by many objects. It's quite unlikely that a reflective IR barrier will ever be broken by a car. Lenses will be required to concentrate the beam, and to exclude sunlight and reflections from the receiver. But similar provisions may be required with laser diodes, to increase the beam diameter (spot size) for easy alignment of the sender and receiver.
The beam break sensor I once made with an IR LED and remote control receiver (no optics on both) had little problems detecting a 5mm diameter knitting needle flicked through the beam.
Leo..
Sorry for my late reply guys! Thanks for your opinions.
mikb55:
Your laser source isn't a source. It's a receiver and your sensor is a laser.
I accidentally switched these two in the list
jremington:
Before moving on to the light gate, you can learn a lot by starting with an Arduino and a simple pushbutton switch.
Make sure you can write code that correctly times how long you pushed the button, time after time. It is harder than it may sound.
I understand. What I'm trying to do here is to explore Arduino stuff, but have these parts nearby. So I'm able to make functional gate, when I'm "ready". I just need to know, if is this solution effective and feasible (with the right code).
Wawa:
Why do people always think "laser".
A common IR diode as used in a remote control and a remote control receiver might be easier.
What distance are we talking about.
Leo..
About 3-5m. Problem is, it's HAVE TO BE VERY PRECIOUS in the time measuring. We are talking about 1/100 of a second standard. How some posts mentioned, I'm not sure if IR will be that exact (with the beam bouncing everywhere).
Without having a part number and data sheet for the sensor all you can do is run the experiment and see if it's fast enough for your measurements. Virtually all sensors are capable of sub-millisecond response times therefore it'll probably work.
To improve the chances of success put your receiver at one end of a long narrow tube such as a PVC drain pipe or water pipe. This will put it in near darkness with only the mirror in its field of view.
Problem is, it's HAVE TO BE VERY PRECIOUS in the time measuring. We are talking about 1/100 of a second standard. How some posts mentioned,
I'm not sure if IR will be that exact (with the beam bouncing everywhere).
~25mA peak LED current through a narrow beam IR LED should be enough to cover that distance.
An Arduino pin can provide that (25mA@50%) without extra hardware.
No problem to have a 1/1000 sec resolution with 38kHz modulated IR.
The IR LED should be a narrow beam (<10 degrees) type.
Current handling is irrelevant. Most of them are 100mA or more.
YOU decide how much current you want/need to push through the LED to bridge the distance.
Leo..
Hi I have just published a project using Xbee radios and IR through the beam sensors to create reliable and accurate timing gates. Please check it out and give me comments.
