Choosing a laser - with or without TTL?

I’m looking into making a MPCNC laser engraver on a budget and am a bit confused on my options for a laser. There seems to be two options, either with or without a TTL driver.

I’ve heard you can get one without a TTL driver and plug it right into your fan port, from

Or with a TTL driver remapped to a 5V port on the board, as explained in the tutorial on this site

So is the TTL driver necessary? It seems lots easier to not have to mess with it. And if it’s not necessary, what’s the benefit of using it?

I am no expert but without ttl I am pretty sure you only get on or off, and I have never ran my laser at 100% power. I think you would lose a ton of functionality without power control.

Interested to hear what other say.

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I agree with Ryan. In the linked article, they are using the fan port to get a PWM signal, which is then almost certainly connected to the TTL input on their laser driver. I don’t see it specified in the post, but I suspect that’s what they are doing.

I have a J-Tech laser on my MPCNC, which has a selector switch between TTL and CW (constant wattage). I’ve never used the CW mode - I only ever use TTL.

I suppose it’s theoretically possible to modulate the power of the laser just by turning it on and off really quickly (using a PWM signal), but unless the driver and laser are designed for that and can turn on and off thousands of times per second I don’t think it would behave as expected, and might affect the longevity of both. If it was designed to do that, they’d just call it TTL.

How much cheaper is a laser driver without TTL?

I think the linked article actually doesn’t have TTL. He links to the laser he bought, and from what I saw doesn’t include the TTL driver.

Probably between $10-$15. It’s just extra work to make sure it’s all set up right vs shoving it into the 12V fan pin, but from what I can see/what you all have said it’s probably worth it in the long run.

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