Analog Modulation Linear Driver

[shokkunlasers]

I want to synchronize an analog audio signal with a laser and this where I came to the problem that I would know how to synchronize it via PWM by amplifying the signal and then use a simple comparator and oscillator to generate my PWM signal which I would use to modulate some standard linear driver setup.

Now I wondered how you would make an analog modulation input circuit for a simple linear IC like a LM317?

First I would use an OP amp to amplify my standard audio signal from lets say an mp3 player a poti to set the voltage gain in order to bring the signal in the right range and a zener to get a nice 0-5V analog signal.
After that I'm unsure how to move on.

I never did something like that so I'm fancy to hear how you would build it.:yh:

 

[ARG]

I tried to build one. It didn't work Curious what other people have to say.

Subbing.

 

[shokkunlasers]

I tried to build one. It didn't work Curious what other people have to say.

Subbing.

I'm also curious but it seems like the people who know it haven't seen this post yet. BUMP

 

[Cyparagon]

I've built two. They've not fancy, but the waveforms look adequate and they've been driving a blue and a red in my projector for a few months now without popping anything. They're roughly based on this design (from benm's page):

I used different resistor values, reference voltages, divider structure, and part numbers, and also added a current bias feature, but that's the general idea.