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Too ambitious for a novice?

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Chucara

New Member
I'm a software guy with a curiosity for electronics. I did a few boards in high school, but I'm almost a complete novice. I know the very basics, but no more.

I do have an idea for a project, but I want to know if this is something I should even consider starting out with as someone who doesn't know much of anything.

I basically want a infrared (or magnetic?) detector that detects when a light beam has been broken. This is for a model railroad project, so the emitter and receiver won't need to be placed more than a inch or two apart.

Now, as I wouldn't know where to begin with microcontrollers (this is where the problem is, I expect) I won't need any processing on the board. I do however want to be able to hook this up to a pc (usb, serial port, whatever) and write whatever logic I need there. Basically, I just want to be able to poll the circuit for it's current status (Blocked: true or false) at regular intervals. Having more than one detector is a plus.

What do you say? Way over my league? Is it possible to buy a kit, or the schematics for this? What do I need to hook something like this up to a serial port?
 

kchriste

New Member
Forum Supporter
Well, since you are a software guy, all you'd need to do is connect the output of an optical detector to one of the handshake line inputs (CTS, DSR, DCD, RI etc) on a serial port. You'd need a small power source for the IR emitter and pullup resistors.
 

ke5frf

New Member
I suggest that RTS and DTR in parallel to a 5 V regulator with respect to pin 7 (ground) could be used to power a 5 volt low current IR diode. External power supply may not be needed for a handful of IR switches. Current limiting both the outputs with resistors would be advisable as well.
 

ke5frf

New Member
In fact, a discarded optical mouse might be a good source for components. Do they make IR mouses? If not, you might be able to devise your switch with visible light LEDs and LSTs from an old mouse and use the same circuit architecture to drive and sense them. Are you a good hacker? You might even get the exact source code from the drivers and make a dandy little gadget. his could be serial or USB based. Just some random thoughts.
 

Chucara

New Member
Wow.. That was a fast response, thanks everyone!

It seems that the task at hand isn't all that daunting, even for me. I did some serial programming at university, but that was a while back, I think I'll manage to brush that up. And I forgot that the diodes and sensors don't necessarily need to be on the same circuit.

Sorry if I don't use the lingo, but I can't say that I know it ;)

For now, I'll just read up on exactly how the sensor works. Can anyone recommend a good source, or just let me know the technical names of the components so that I can google them?

I already have the IR diodes, but nothing to detect the light. What is the sensor called? A search on 'ir sensor' seems to leave me with some more advanced components.
 
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Chucara

New Member
A switch? I see. Wouldn't have guessed that ;)

Thanks for your help. Now I'll just ponder on whether to do this through serial, or through arduino.
 

ke5frf

New Member
Usually the sensors or switches you are talking about are either IR sensitive transistors. But as I suggested earlier, visible light frequencies would likely work here too, in that case visible LED and LST (light sensitive transistor)

This would be an opportunity for me to rip open an old optical mouse and salvage stuff for my project.
 

Chucara

New Member
I bought a Arduino kit that includes an LDR and I've managed to get everything to work with my pc rather effortlessly. I haven't tested it yet with an IR diode.

I looking forward to seeing how it will work in daylight - if the change in light using an IR diode is enough to detect reliably. A IR filter made from some unexposed, developed negatives might do the trick, but no idea yet.
 

sfink06

New Member
Great, can't wait to hear how it turns out! I'm working on a similar project, trying to build a circuit that will allow my arduino to discriminate between 4 lights pulsing at 80kHz, 60kHz, 40kHz, and 20kHz.
 

Vizier87

Active Member
Since you're a software-person, why not use image processing? A webcam, USB connected, processed using Processing or MATLAB, you won't even have to touch a soldering iron.
Of course, technically it's more complex, but since you're already good at programming... why not?
 

Sceadwian

Banned
Vizier, I think that's the only thing I hated about Processing, it requires you to install Apple Quicktime fro the image capture to work =( I detest quicktime.
 

Chucara

New Member
Vizier: Well.. for this project, I need several points of observation. It's for detecting when a train passes certain points of a model railway. A webcam for each point of interest would be way more expensive than an LDR and a IR diode.

Also, I've already fiddled around with webcams, and I've always wanted to learn more about electronics. ;-) The arduino lets me do that without reading Horowitz from end to end.

For IR data on a PC, IMHO nothing beats a Wiimote, which does all the processing you'll need without all the fuss, and it's even Bluetooth based. However, I must admit that I don't really know what Processing is, and while we did use Matlab at university, I've never used it as more than a very advanced calculator. I'm mostly an OO (.Net) guy these days ;-)
 
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