Topic: Need help with creating a laser pointing system

[nkaddy]

Hi everyone,

I'll start by saying that the work and info on this site is incredible! You guys are amazing!!

I'm trying a build project to make a joystick activated remote laser pointer, this will involve sending a set voltage to the galvos until a change is required. I have a few lasers to hand, but I will only use one so I'm not bothered about switching signals and I'm not confined to IDLA architecture. The other aspect is that I would like incorporate is running two galvo sets off the same DAC sound card. If I build a soundcard DAC, would this mean that I would need four channels [X1 Y1, X2 Y2]? And am I right in assuming that given the board is a collection of 6 correction amps then this would be fine? Also, I'm happy to sacrifice the output plugs on the soundcard, can I use these instead of soldering directly onto the soundcard? Finally does anyone have a wiring diagram for the complete soundcard board with all 6 corr amps in place?

Sorry for the long monologue, I'm just very excited by this project! And I'm a complete noob at this stuff, so please be gentle this is my first time!

[James]

Hello nkaddy. Welcome to The LaserBoy Forum!

Let me see if I get what you are saying.....

You want to create a kind of remote control for a laser pointer using galvos and a joystick? That should be pretty easy, actually. Since the correction amp was designed specifically for the purpose of correcting a varying voltage that is all positive, all you need to do is replace the sound card with a joystick with about 2 volts DC across the pots. Send the wipers to the correction amp channels for X and Y.

You could even simplify things a lot more and just use some batteries! An AA or a similar single cell battery will give you about 1.5 volts. Get an even number of batteries and put them all in series. Tap a wire on each end and in the center and you will have a differential power supply with positive, negative and ground. Put the positive and the negative across the outside leads of the joystick pots and send the wipers and the ground to the scanner amps. No op-amps required.

Do you want to send independent signals to the two different sets of galvos? If so, then yes, you will need 4 channels of sound card and correction amp for that. If you want to send the same signals to the 2 sets of galvos, then all you need to do is jump from one to the other. The op-amps have enough current to drive 2 sets of galvo inputs.

If you get an 8 channel sound card, you can build 8 channels of correction amps. Then you would have a more flexible system. All the channels of the correction amp are exactly the same. So you can use them either to control galvos or color modulation.

You really need to solder on the sound card. You must get the signals straight out of the DAC before they go though the output decoupling capacitors.

My suggestion for building your own correction amp would be to get an electronics bread board and lay it out on that. Make sure it all works and then get a copper clad board with about the same layout as the bread board and solder it.

The board pictured here is for an 8 channel sound card and has 8 channels of correction amp.
http://laserboy.org/forum/index.php?topic=8.0