Author Topic: So mine is TTL?  (Read 1004 times)

Tom

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So mine is TTL?
« on: March 27, 2017, 02:21:10 AM »
If I received the Mana SE board and this laser, does this mean that mine is TTL controlled? I need to do more reading on exactly what TTL is.

Zax

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Re: So mine is TTL?
« Reply #1 on: March 27, 2017, 04:27:24 AM »
Yes it does. All of the new systems use this setup, I guess they saw what we were doing  :D .

Parnold

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Re: So mine is TTL?
« Reply #2 on: April 17, 2017, 05:56:31 PM »
At the risk of sounding ignorant....  I have the same board and laser module on the A3 Pro I just got a couple weeks ago.  Everything I read said it was a PWM laser module.  Are you saying the Mana SE will also control a TTL but the unit came with a PWM module?  I'm seriously considering a 2000mw TTL, but after scouring the boards, I'm still not clear on how easy or hard the conversion will be. 

I have issues with trying to do any lengthy or complicated burn, which I attribute to overheating since I can complete the really complex stuff, but I have to pause the unit several times during the burn.  From your recommendations Zax, it sounds as if this shouldn't be a problem with a 2000mw TTL.

If there is a thread that explains the conversion, please point me to it, I've been unable to locate one simple enough for me to follow.

I am really trying to find my own answers and not ask dumb questions!  :-[


Zax

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Re: So mine is TTL?
« Reply #3 on: April 17, 2017, 05:59:07 PM »
The Mana SE can drive either, as can the earlier models (they just don't have a connector so you have to take the TTL/PWM from the jumper).

If your laser has 2 wires it's not TTL, although some have an input for it that can be connected.

Parnold

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Re: So mine is TTL?
« Reply #4 on: April 17, 2017, 06:21:51 PM »
Zax, thank you for the fast reply..  you are the best.

My laser module has a plug with three wires on the top, so TTL it is!  Now for one last question, then I promise I'll go back to scouring the threads trying to put this all in place in my old brain.  If I order a 2000mw TTL module, it should be somewhat plug n play?  I assume that the detached board will be needed as it's not part of the laser module like the one Banggood included with the engraver, and I'll need to either use a 12v power source, or steal 12v off the Mana SE?

Gotta admit, tweaking my 3D printer was a lot easier, lol.. all mechanical stuff.

Thanks in advance!

laser_cutter

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Re: So mine is TTL?
« Reply #5 on: April 17, 2017, 06:25:43 PM »
The Mana SE can drive either, as can the earlier models (they just don't have a connector so you have to take the TTL/PWM from the jumper).

If your laser has 2 wires it's not TTL, although some have an input for it that can be connected.
 

The difference between TTL module and PWM module should be a sticky thread with pictures. More and more individuals who purchase these low power laser are not electrical engineers.   


« Last Edit: April 17, 2017, 06:26:46 PM by laser_cutter »

Zax

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Re: So mine is TTL?
« Reply #6 on: April 18, 2017, 05:14:52 AM »
I would get the latest lasers that have the board on top, I think banggood has most of them available. The older 2W like I have with the external board works too, you just have to mess with the wiring.

av8r1

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Re: So mine is TTL?
« Reply #7 on: June 23, 2017, 02:05:29 AM »
 

The difference between TTL module and PWM module should be a sticky thread with pictures. More and more individuals who purchase these low power laser are not electrical engineers.

I'm not going to upload any pictures, but I think I can explain what these terms are and how they relate to us boys what play with lasers.

TTL stands for Transistor-Transistor Logic, and it's a standard for the manufacture of digital logic circuitry, one still in heavy use today.  The part we need to know for this discussion is that TTL chips operate between 0 and +5 volts, with 0V being logic 0, +5V being logic 1.  Our Arduino microcontrollers put out TTL compatible signals.

PWM stands for Pulse Width Modulation, which is a very handy way to get digital circuitry to pretend it's analog.  What we do is output a square wave--basically rapidly flip a pin from 0 to 1 at a constant frequency--but vary the ratio of ON time to OFF time.  If our output is 0 to 5 volts, and it spends exactly 50% of the time on and 50% of it off, on average there is 2.5 volts on the line.  Using a simple circuit called a low pass filter that consists of a resistor and a capacitor, we can smooth out the pulses into a DC voltage.  If we change the duty cycle to 75% on and 25% off, we'll get a voltage of 3.75 volts.

The Mana SE controller has a TTL level PWM output for laser control.

Here's how that relates to us as laser machine builders:  Your laser module will consist of the diode itself, a heat sink and fan, probably a circuit board, and a two- or three- wire input.  The circuit board is a constant current power supply, it's job is to feed the diode with the correct amount of power (if you were just to hook up the diode to 12V power, there would be a very brief, bright flash and nothing ever again).  How we turn the laser on and off (or make it output a variable amount of power) differs depending on how many wires we have.

On a 2-wire laser, those wires are +12V power and ground.  The actual switching of the diode power on and off happens on the microcontroller board, the driver board on the laser gets a pulsed power supply.  Depending on how sophisticated the driver is, it will either pulse the laser light (which, when etching, essentially dithers the image by dot density modulation) or if there's a proper filter capacitor, the laser will emit a continuous light of varying brightness.

On a 3-wire laser, the wires are power, ground, and signal. The power switching to the diode happens on the driver board.  From a brief experiment I did a few days ago, I can confirm that the driver board isn't actually looking for a PWM signal, it's looking for an analog signal, as I fed it a true analog signal from my power supply and it varied the brightness of the laser accordingly.  So I'm willing to bet it has a low pass filter to smooth out the PWM signal coming from the microcontroller, and then varies the current to the diode based on the signal duty cycle/voltage.  Disclaimer:  I have not reverse-engineered the driver board that came with my laser kit, I can't read the labels on the chips, this is based on my observations and understanding.

For those wanting to learn more stuff at this level, check out the youtube channel Afrotechmods.  He does a pretty good job of explaining things.

Stonemull

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Re: So mine is TTL?
« Reply #8 on: June 23, 2017, 02:29:43 AM »
I reckon the time constant of the input filter is a little less than 1mS too, 1kHz PWM results in a fairly notchy PCB etch, so I recompiled for 8kHz PWM.
A3 Eleksmaker 2500mW
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ggallant571

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Re: So mine is TTL?
« Reply #9 on: October 23, 2017, 08:08:06 AM »
If the time constant on the input filter is 1ms, running faster will not help. I would slow down the movement such that you get more pulses per mm.

If my math is correct - at 600mm/min the laser travels 1mm in 0.1 seconds. At a 1KHz  pulse rate that is 100 individual burns. Speeding up the laser travel to 2400mm/min would reduce the count to 25.

Please verify my math!!!!!

BTW - I switched to 8KHz over a year ago on a 5.5W non-ttl module.


SARCASM - Just one more service we offer here.

Zax

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Re: So mine is TTL?
« Reply #10 on: October 23, 2017, 12:34:55 PM »
In T2Laser the firmware "Grbl 1.1f High Freq PWM" is 7.8kHz compared to the default 1.1e that is 0.98kHz.

stk2008

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Re: So mine is TTL?
« Reply #11 on: October 23, 2017, 02:20:36 PM »
Zax in another thread u suggested to try 1.1f for my

Eleksmaker 2.5 manase with the blue laser.

Im using 1.1e if i use the high frequency firmware will that not damage my driver or laser running it faster than its meant to?

Zax

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Re: So mine is TTL?
« Reply #12 on: October 23, 2017, 04:12:57 PM »
No, it won't damage anything for a brief test. If the driver is designed for a 1kHz PW and you send it a 7.8Khz one it may not "see" the correct signal so worst case it would flicker.