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Messages - Agastar

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16
General Discussion / Re: TTL Controller Boards
« on: December 30, 2016, 06:56:59 AM »
The driver I designed should keep floating pins from turning on the laser but what it can't stop is if the pin is set high for a brief second unexpectedly as ggallant571 noted. I spent a good bit of time trying to make sure these things don't happen and while I can't stop them all from happening, most scenarios should be covered with this design.

If you do get the board from my signature, just omit the "TTL" components (Q1, R9&10, and P4) for now. This obviously needs some work :)


17
General Discussion / Re: TTL Controller Boards
« on: December 29, 2016, 11:06:41 AM »
TTL has been used interchangeably with these machines which is why I called it TTL on the board. It is really nothing more than a 12V PWM signal since it goes through the mosfet and it was added just so people could use the Eleks board's laser socket.

PWM pin for driving it right off the  arduino pin or the TTL socket if you want to just plug into the laser socket on the Eleks Maker board. Maybe I should have called it something different lol.

I removed the mosfet and 100 ohm resistor from the spice circuit just like you removed it from the Eleks board and I even dropped the PWM voltage down to 4v and it still says it's supposed to work.

Well, now you have me stumped. I'm going to have to noodle on this one for a minute or two lol.

18
General Discussion / Re: TTL Controller Boards
« on: December 29, 2016, 10:48:02 AM »
John, trace didn't help me out here..
Laser stays off, what should i try next? Remove the TTL input?

Yeah you can do that if you don't want to use the TTL input and just drive it from the PWM input.

You can eliminate the TTL components and just use PWM but if that works then that should confirm what what I found in LTSpice.
 

19
General Discussion / Re: TTL Controller Boards
« on: December 29, 2016, 10:39:11 AM »
Tried this, but now laser doesn't turn on..

And that's after hooking it up like the highlighted trace in this picture?

20
General Discussion / Re: TTL Controller Boards
« on: December 29, 2016, 10:28:34 AM »
just upgraded my laser to the Banggood TTL Laser and I am getting the laser turning on when connecting to the controller. So I would guess its the firmware/controller and not your TTL board.

My design is supposed to eliminate this but apparently I missed a trace that needed to be added to the PCB and this happened lol.

For me, this is a safety issue and my driver needs to be able to account for stuff like this.

Hope that helps :)

21
General Discussion / Re: TTL Controller Boards
« on: December 29, 2016, 07:01:38 AM »
Here is a screenshot of the fix and the rearrangement of the components away from the mounting holes.

22
General Discussion / Re: TTL Controller Boards
« on: December 29, 2016, 06:55:09 AM »
While playing around with LTSpice I think I may have found the problem. I need to add a trace from the TTL+ pin to Vin+. This is because Q1 needs a positive voltage to be at its base pin and it would if the laser connector were connected but it wouldn't be if just using the PWM pin as in your case. The + pin on the Eleks board is the same as Vin so we can add a trace and fix the problem.

If you have some small hookup wire, you can solder a piece of wire between the + pin on P4 and the + pin on P1.

Here is how I found it in LTSpice. Notice that Q4 (which is Q1 in the Kicad schematic) always has 12V going to its base pin.

https://drive.google.com/open?id=0Bwmqk1fGmLJnXy01Q0VsN2hiRVFFSVFYbmRfUHpkdUVlcFlR

In this screenshot I cut the 12V trace going to the base of Q4 but the PWM pin is still controlling it. This simulates when you have the arduino powered on.

https://drive.google.com/open?id=0Bwmqk1fGmLJnampjMXFteFYxUl8yOGdvVkN5VDduUGZHb2c4

In this screenshot, I also cut the PWM trace to simulate when the arduino would be off. My guess would be that you should see similar numbers on a scope.

https://drive.google.com/open?id=0Bwmqk1fGmLJnR082bW1uN0dYajNNUXFNME1QelNndGs4cURJ

Edited to fix broken image links

23
General Discussion / Re: TTL Controller Boards
« on: December 29, 2016, 05:35:32 AM »
Thanks, I will see if I can move the components away from the mounting holes.

Can you do me a favor and scope the base pin of Q4 and then the DIM pin on the LED2001 with the usb cable unplugged and let me know what see? Anything over 1.1V on the LED2001's DIM pin is considered high.

I'm playing around with my LTSpice circuit to see if I can see what could be causing this.

24
General Discussion / Re: TTL Controller Boards
« on: December 28, 2016, 05:52:36 PM »
Wow, that bike looks good!

Yeah I have the two wheel laser carrier but thanks for letting me know. I'll see if I can get some measurements for the one you have and whip up a model of it so I can see what is going on.

Keep up the awesome work!

25
General Discussion / Re: TTL Controller Boards
« on: December 28, 2016, 02:47:23 PM »
Ok, I think I figured out why. It looks like I need to add a 10K pull down resistor from the Q4's base pin to ground. This should resolve the issue with when uploading new firmware, it fires the laser as well.

I'll get the project updated and upload the new version. You could add a 10K resistor from the Arduino's pwm pin to ground on the Eleks board if you wanted to test it out.

If you don't mind testing that out for me, I'll cover the cost for the replacement boards from OSHPark.com. :)

Thanks for your help!

26
General Discussion / Re: TTL Controller Boards
« on: December 28, 2016, 01:59:23 PM »
I saw the JST connector you added to the Eleks board and thought you might have wired up the pin marked P to the PWM pin on the Arduino. Ok so the PWM pin on the Arduino is going to the PWM pin (middle pin of the 3 pin JST connector) on the laser driver.

I'll take another look at the schematic and see if I can figure out why it is doing that.

27
General Discussion / Re: TTL Controller Boards
« on: December 28, 2016, 01:40:17 PM »
Hmm, are you sending the P pin on the Eleks board to the middle pin of P1 on the driver board or are you using P4?

28
Projects / Re: Show me your grayscale!!!!
« on: December 28, 2016, 06:43:52 AM »
HAHA! I'm still alive aren't I? LOL.

I got extremely lucky with the settings. His laser uses coreldraw to control it and when I clicked on the engraving button, it was set at 400mm/sec and the power on the laser was set to 13 watts. The only thing I adjusted was the resolution from 2 to 3. I'm not familiar with Coreldraw but the way he explained it to me, it works the same as the resolution we use in T2L and a setting of 3 means more space between each laser pass.

29
General Discussion / Re: TTL Controller Boards
« on: December 28, 2016, 06:36:57 AM »
WOOT! WOOT! Sounds exciting! Thanks for sharing your build progress :)

You probably already know this but I'll post it here for the benefit of everyone. This revision incorporates several changes that may need some explanation.

Power on PWM pin hold high & output disable circuitry.
The LED2001 chip will not fully enable the output until the DIM pin has been held high for at least 1ms after the board has been powered up. This caused an issue with engravings that started with less than 100% power or when trying to turn the laser on at low power for focusing. The workaround was to pulse the laser at 100% power for a second when I first turned the machine on. This got annoying quick so I added the circuit to hold the DIM pin high for 2ms and to disable the output during that 2ms period.

Th circuit to hold the DIM pin high and to disable the output was done with transistors and an RC timer. The transistors and RC circuit form what is called a one-shot gate. While the capacitor is being charged for the first time, the PWM pin is held high and when the capacitor is fully charged, the DIM pin is returned back to low (0V). There is also a transistor between the FB pin and the VREF chip. This brings the voltage at the FB pin up to 2V which reduces the current to the output down to a few mA.

During startup, the blue LED on the output should not light up indicating the output remains off. Scoping the DIM pin and powering the board should result in a 2ms pulse. The output should remain off during this time but should be fully functional after.

New 12V/5V power options for the fan connector.
Previously, the fan was powered by the same power-in as the board, typically 12V. In this revision, a 5v regulator has been added to support the power-on one-shot gate circuit. The 3 pin header was added so that the voltage source for the fan can be configured with a jumper to be either 12V or 5V. The datasheet for the 5V regulator states it has a max of 300mA so just make sure the 5V fan you use draws less than that.

New TTL Connector for driving the laser from the 12V laser fan on the Eleks boards.
This connector was added specifically to support connecting directly to the Eleks board's 12V laser connector. Note! This was designed to work with the mosfet that is on most eleks boards. This means that the input is inverted and a logic high is off and logic low is on. This is because the laser connector's + pin is connected directly to 12Vin of the board's power supply and the - pin goes to the mosfet and then to ground.

The PWM pin that is part of the 3 pin JST connector is NOT inverted and logic high is on and logic low is off. This pin can be driven directly from the arduino's PWM pin.

Hopefully this was helpful and I look forward to seeing the progress you make :)

30
Projects / Re: Show me your grayscale!!!!
« on: December 27, 2016, 08:19:37 PM »
Thanks! I have more pictures if I can remember to get them off my wife's phone :)


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