Morning,
I have posted a couple of times with great news! Since starting this project I do have a working laser projector whic has been by far the 'coolest' project, however I am now looking to solve possibly the finally hurdle.
Currently I am using an audio card which works flawlessly and I am really happy about it's results. For those of you who don't know using an audio card is perfect for the job and sending 6 channel audio with a correction amplifier for the galvos works fine.
Up until this point - the software I have created allows me to generate audio from ILDA files, my issue is the following.
The laser module accepts a TTL signal, either high or low. Currently I have written in the software to output High or Low(audio max or audio min) to turn the laser on/off at the correct time which works...
There are two main reasons why I want to incorporate a better solution.
- It's too bright - feedback from friends and family is that after watching the show their eyes begin to hurt, really bad for safety and currently no ability to turn the brightness down.
- I can only display 8 colours max. - I want each R G B laser to be 8 bit such to see the ILDA projections how they were supposed to be seen.
What have I done to try and rectify the problem? What am I asking for?
I started by trying to modify the open source Helios DAC show card. I had some good progress with this, This would solve all the problems and even update my projector to be fully USB. I could then use other pieces of software and not my home made software. I won't go in too much detail but I essentially wanted to output a PWM signal from this instead of an SPI which chucks the values down a DAC. Could I not just buy one? Yes - but I would actually be in the same situation. Does it work? Sadly no, not much user support on writing code at home on a specific SAM4 arm cpu...
I have today put an arduino in between the laser module and audio sound card. I could easy read the analog voltage and set a PWM to a mapped value form the signal. In my head this works great. However the arduino I am using is not up to the challenge. I think the program is running two slowly. I need to analog read 3 signals, do some quick math, and generate a PWM at a frequency of at least 40khz - (Nyquist theory, but probably more like 4x).
A couple of pictures of this attempt can be found attached.
I thought about a VCO - voltage controlled oscillator? But all the chips don't have the frequency I am after...... Those who have built one, what did you do?
Does anyone have a analog controlled laser module to their knowledge?
Thank you, I am happy to discuss with anyone who wants to build one....
TLDR - Analog voltage to control a TTL laser module.