Question on Laser Pointer

I would like to add a laser pointer to my robot.

The laser found (have to put the link in next post), says it can be turned on and off with a TTL input. So I would plug it into the rx/tx right? The robot will all ready be interfacing the computer through the serial to usb, and I thought you could only do one tx/rx option.

Or can the laser be plugged into any digital input?

Or can the laser be plugged into any digital input

Can I suggest a digital output?

Haha! Guess there is a difference between input and output ;)

Here is a link with some smaple code. Yes this is controlled by a digital output pin.

For that amount of money, you could probably buy 5 laser modules out of China, plus the resistors and transistors needed to control them with a TTL digital signal.

Basically, think of a laser module as a 3 volt DC motor; the interface (using a simple transistor/mosfet/darlington driver circuit) is the same, you could even easily hook up a small cheapo keychain laser from your local dollar store and run it this way.

If you are looking for laser modules then I bought a load in bulk so I could send you some for £2 each plus P&P. ;)

Link doesn't want to work here at the moment so I can't check how expensive that linked one was but from what was said, I presume it was pretty expensive. [edit]Yeah, link worked eventually now.[/edit]


If you are looking for laser modules then I bought a load in bulk so I could send you some for £2 each plus P&P. Wink

Sorry, using university funding, doubt I could do that.

It was around $19.00 US, mowcius; for a digitally (TTL) controlled laser module; it has a pigtail with a connector (IIRC: 5v, GND, and control TTL), a PCB with the laser, driver, and control electronics. If the guy has funding, though (he didn't say that up front), then it probably isn't a big deal unless the funds get tight (I assume he has a parts budget already worked out, in that case).

I consider $19.00 pretty expensive for what a $2.00 laser and a 10 cent transistor can be substituted...

If you are in the US then vitual village sells them. (they have other stores too - I use the UK one)


That's a pretty good deal for the 100mW module; I have a green laser pointer that is something around that (got it before the ban here in the USA went into effect), and that thing is blindingly bright.

About the ban: Basically, you can import or sell any device meant for certain uses (entertainment, mainly) that incorporates a laser diode module in excess power of 5mW that can be seen with the human eye (free range?) - but you can import/sell the modules themselves (or devices in which the laser is contained, like DVD burners and such).

It is a stupid and reactionary ban, which is something our legislators here (and the people who elect them) are experts at creating. How I often wish we would grow a spine (I don't intend to say anything bad about your countrymen, mowcius, but I have a feeling there is this weird positive feedback loop between our two countries when it comes to "safety for the citizens")...


I have heard and read all about the various bans on laser pointers. Yeah I suppose it is to 'protect the general public' or something like that. I'm sure a lot of people still get/have very powerful lasers they shouldn't have. I was thinking of getting a brighter one but then I thought, I have no need and therefore I would probably do something I would regret with it.

People just need to be sensible with these things. My 5mW green one is pretty bright but I am careful with it.


There does seem to be a run on new laws that 'protect the public' or ' think of (or protect) the children' and I don't expect them to stop thinking of more things to ban or limit in the future. Using common sense or just using the existing law to handle the idiots that try and flash airplanes with their lasers would seem to be enough, but some politicians will always look for thing to make them seem more effective and caring to their electoral base.

But what the hell, I'm an outlaw, I still use lead based solder. ;)


I'm sure a lot of people still get/have very powerful lasers they shouldn't have.

Yeah - I probably shouldn't have that laser I have myself; my friend and I got it when we were working together on the UGV (that I am now working on alone). We had gotten it as a "sponsor-product freebie" from some laser supplier in China; its a nice laser pointer, aluminum body, runs on 2 AA cells, 100mW+ output, green laser. They sent it to us as sponsor help.

We intended to use it for a homebrew LIDAR system, but it turned out to be way, way brighter than we were expecting (it came with black balloons and such to pop; if you hold it against your skin you can burn yourself!). Since it is so bright, I'll probably go back to using a fallback device I ordered, which is a 5mw laser module that projects a cross (via a diffraction lens on the front); projecting that thru a grid diffraction grating will give me a lovely pattern of crosses (almost a grid) that I can triangulate off of. Unless my webcam can't see it in the daylight - then it might be back to the green beamer.

But what the hell, I'm an outlaw, I still use lead based solder.

I still have most of a roll of 1 lb lead-based solder I purchased from Radio Shack almost 20 years ago; I don't know if I will ever use it up before I die. Even if I did, I know a place here in Phoenix where I can buy 10 lb ingots (among other forms used in industry) of lead solder if I needed it.

I think the push for lead-free solder is going to be the death of electronics (well, more like the death of our pocketbooks - I am sure that some of the issues relating to consumer items dying after only a few years of usage are related to this), unless they can work around the tin-whisker issue. I am just glad that my prized antique electronics (like my Altair), while they may have other issues (dust and age, mainly) that right now prevent them from working, I at least won't have to worry about microscopically small shorts killing them or causing issues.

Of all the things in this world causing pollution concerns...

Let's not worry about the island of trash the size of Texas swirling in the Pacific ocean. No, no - lead-based solder is the real evil!

(like my Altair)

Wow that's cool. Brings me back to the CP/M days and several Kaypros I owned. It still pains me to think how much $$$ that old stuff cost new compaired to todays even inflated dollars. ;) My Kaypro 10 with a 10 Mb hardrive cost like $2,700. :o


Wow that's cool.

I nearly shat a brick when I saw it - conveniently at the same place I can buy the solder at (Apache Reclamation and Electronics). It was sitting outside on top of a chair, exposed to the elements. I hadn't seen it sitting there before, so I asked a guy (one of the owner operators of the place) how much he wanted for it. He said "Well, some guy pulled it out of that trailer, and said it was an antique - I let you have it for $100.00" - me, I tried to to dicker with him: "I'll give you $50" - him: "Nope, $100 firm" - me: "Oh well, ok - you drive a hard bargain mister".


I was just trying to see if I could get a $50.00 Altair. It has the flat toggles (indicates early model), but is missing the top cover, and is very, very dirty (it needs a complete teardown, cleaning, and rebuild). The company that made the case no longer makes the case or cover, so when I get-round-toit; I will need to have that part custom machined. It also came with a ton of boards (and the next week I went back looking for the cover and found some more) - lots of memory (over 64K worth), a disk drive controller board (for a fixed hard sector drive, unfortunately), serial/parallel port boards, plus the CPU board (unfortunately or fortunately, depending on how you look at it, it came with the Z80 board - I wasn't able to find the 8080A board it would have originally come with).

I posted a little blurb about it on an Altair newsgroup I found, and was immediately offered $900.00 for the thing in its current condition, but I won't part with it for that. I have always wanted one from the day I first heard about them as a kid; I am a computer history geek (I would love to own a single brass piece of Babbage machinery - I doubt that will ever happen).

Maybe some day I will interface my Arduino to my Altair - now that would be a funky "meeting of minds", if you will! Probably would also be almost the only way I could get it connected to the internet (not really, though - plenty of vintage 8-bit machines have ethernet boards that enthusiasts have built - I wouldn't be a bit surprised if there were one made for the Altair).


Yeah I also still use lead solder occasionally although I have more recently switched to lead free for most things due to obtaining a 500g roll and my leaded is nearly out.

The leaded is definitely better for the smaller stuff where I need a better flow. My leaded is also a smaller SWG than my lead free.