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I have purchased this laser with a driver from Ali. I connected the laser to the driver and the driver to a 12V DC and the TTL to 5V (which I then disconnected since the applying 5V to TTL actually turns the laser off). When I first turned power on, the laser worked fine and I was able to burn some paper for about 60 seconds before turning it off. Then when I tried to turn it on later, it no longer worked. (I can no longer return the laser since I had it home too long before getting around to testing it) I tried pulling down the TTL by shorting its pins first through a resistor, the directly, leave them floating, apply 5V to them... but nothing.. the laser no longer turns on, only the fan on it spins.

If the problem is in the driver board then I could just buy a new one since it costs only ten bucks. But how do I test that the laser itself is working fine? I was thinking about taking a PSU from an old computer and connecting the laser to the 12V DC output from the PSU. Computer electronics are very sensitive, so the PSU must have a nice, clean and smooth 12V output right? Will that work?

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  • \$\begingroup\$ Is the first part of the question really relevant? I was reading it and wondering how the heck we should know what's wrong with your setup. But it seems like your actual question is only the 2-3 sentences at the end, is that right? \$\endgroup\$
    – pipe
    Nov 22, 2018 at 16:09
  • \$\begingroup\$ It's definitely relevant since someone can possibly notice something I have done wrong during the original testing, revealing that there is no problem with the driver board and it was just some easily fixable mistake. \$\endgroup\$
    – Askerman
    Nov 22, 2018 at 16:15
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    \$\begingroup\$ Do not try to drive the laser directly. You will destroy it for sure (if the driver didn't do it already.) Try to test the driver first. \$\endgroup\$
    – JRE
    Nov 22, 2018 at 16:44
  • \$\begingroup\$ The laser is effectively an LED with an exceptionally large heat sink, so you could test it, but you would do so by using a voltage or current regulator to slowly increase until you confirm function, or start with a single double A and a 10 ohm resistor and briefly tap the wires together to complete the circuit, then try with 2 AAs and 3. If the LED comes on at all, it is almost certainly fine. It's difficult to get one to fail in a way that leaves any function at all. \$\endgroup\$
    – K H
    Nov 23, 2018 at 0:13
  • \$\begingroup\$ I have a buck converter, so if i set it to 0.5V and slowly raise the voltage the laser led should turn on at some point safely? \$\endgroup\$
    – Askerman
    Nov 23, 2018 at 9:50

1 Answer 1

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As JRE wrote in a comment: No, you should not drive the laser directly from the computer PSU.

Computer electronics are very sensitive, so the PSU must have a nice, clean and smooth 12V output right?

The first part is mostly correct, computer electronics are very sensitive, but your motherboard and GPU probably has dozens of high quality low voltage regulators on board, to convert the 12 volts down to 100 amperes of a various mix of voltages in the order of 1-3 volts or even sub-volts. Nothing these days are driven directly by the 12 volt line except the fans and possibly USB3 in one of the fast charging mode.

This means that the 12 volt output does not have to be very stable at all. The regulators are able to handle an input variation of several volts up or down.

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  • \$\begingroup\$ Doesn't the laser driver do exactly that - convert the 12 V to something the laser can use? \$\endgroup\$
    – D Duck
    Nov 22, 2018 at 19:03
  • \$\begingroup\$ @DDuck The driver does. He wants to run it without the driver. \$\endgroup\$
    – pipe
    Nov 22, 2018 at 19:06

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