Moon Laser - Laser projector Part 1
A few years back i got this idea to play games on large walls on the side of buildings using a projector. Simple stuff like Mario Kart and the projected image was not very large.
The limitation of the projector light sources limited the size of the image but i thought why not use a laser. Lasers don’t have focus problems and hardly loose brightness over distance compared to standard projectors. They are however vector but that wont create problems for old-school style games like Tetris, only 30m high!
Laser projectors work by having very fast moving mirrors to reflect the laser light very fast and are often known as “Galvos”. After some research i found it too difficult to make the laser galvo’s from scratch so i bought a small 30,000point per second galvo and its controllers off eBay.
To interface this galvo with a computer i needed a DAC or Digital-to-analogue converter that outputted 0-10v on two points. I hacked together one on some breadboard from a SMD MCP4922 i had lying around.
This worked for a while but i got sick of having to reconnect the board when i wanted to use the host arduino for another project. (it would have probably been much easier to just buy another one but this way was more fun) So i did what any insane person would do and build a PCB for it. I needed to get another board made so i just joined the orders.
Its a fairly simple layout in EAGLE CAD
Then send off the circuit boards for manufacture! They came back looking pretty good!
I put it all together and connected it up to an Arduino and it was like magic! All except for a pull down resistor on the chipselect pin i missed on the revision i sent off to get made (updated schematics shown above)(you can never get it right the first time….)
Unfortunately when i started the thing up to test the powersupply for the laser galvo broke :( its a weird 2 rail 24v -/+ supply and i am yet to find something to replace it with. I may have to build my own :P