You can just buy some PWM boards from ebay with a pot and knob ready to use for around 2 dollars each, remember you want to modulate @ 5v to your driver and 10k is usually fine.
I want to make another laser spiro and mount it all in a box with batteries to be portable, I glue mirrors to brushless fans and use a PWM signal to control the fan speeds as well which changes your patterns and I built my modulators on a project board before as I was adjusting my range, but I may or may not use this RGB, it has a near perfect blue-green mix but the red is slightly different as for beam dia. and I have other things going on, I may not do anything for a while until I have time and am in the mood.
give it 5v in and set your freq to 10k should be good then you can play with your duty cycle to adjust each lasers brightness, the frequency just needs to be set within the laser drivers acceptable range, 10k is usually good and the duty cycle adjusts your brightness by how long it's on and off during each cycle, it looks steady to our eye, only thing is you have to step through each channel so you might just get 3 individual pot adjustable PWM generators or make your own.
ou can easily use to control your RGB brightness/mix you need to buy 3 of course.
Better yet use they are set to 10K so just give them 5v and turn the knob once connected to your drivers TTL ports, observe the correct polarity.
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