I am not really sure why it is getting hot... I have a generic clone "CNC Shield v4" from aliexpress it is based off the original design found here
I had to modify this clone shield because the microstepping pins were pulling to gnd and not 5+. Once corrected it has worked great...until I added the laser.
It is overheating on or near the LEDs on the NANO. I noticed that the two steppers started losing steps so I grabbed my IR camera and noticed that the area near 'L' was over 150F and climbing. I thought it was because I was using the 3.3V pin at the end of the nano.
It appears that 3.3V is actually stepped down from the 10V input of the shield through the arduino. SO I switched to the 5V power, near the shield's reset button. BUT it is still overheating. When the laser is removed no overheating. Makes me think that 5V is also through the arduino. It is a 50mW 405nm UV laser...it is within the limits of the nano according to the specs I read...even if it was just the nano powering the laser...
I know it is possible to drive a laser and several steppers with this board...why is mine overheating?
It is a 5mW UV laser pen...that I disassembled(and I am learning that cheap is not always the right way)...lol.
It looks like it can use up to around 250mA, will try and confirm with meter in series tomorrow.
BUT I have the laser connected to the 3v and gnd at the end of that shield, but a transistor set up on a data pin breaking that gnd. Giving me ability to turn on and off.
When off via data pin heat is fine, but whether on the 3V or on the 5V with a step down, board is getting hot.
No schematic currently.
This is the the monstrosity that my son and I are trying to build.
The creator does not have a schematic I could find either, so a lot of freezing the video and tracing wires...and dissecting code to get the right answer. Which I cannot complain about too much. The things is working...perfectly, but it gets hot. Thinking of injecting additional power, or modding shield...maybe.
Wanted to update with the modifications I had to do to this cloned board. Seems there were a couple issues. BUT I have it working perfectly until I add laser and it overheats in about 3 minutes. I should say, it works like the video of the og creator...then slowly gets hot.
Not the best of starts. We need one in order to see exactly how thing are wired up so we know how to fix them.
I would keep the ground connected and break the voltage supply. You will need to use a PNP transistor to do that. This is because you don't know the control circuit inside your pointer, and it is very likely not to work correctly if there is no ground connection.
That looks way too much to be trying to supply through the internal regulators, it is no wonder they get hot
Controlling a laser, is not as straightforward as just turning on an of the power supply to it. You normally need a laser driver.
This link is a good place to start although the schematics are text base so they can be hard to read. It does say that all the control and drivers are in a pointer so that may be the best way to start.
I am reading about the overheating problem when people are trying to run certain LEDs...without current limit. People are suggesting adding a resistor, is that a possibility?
I will also try changing transistor setup...I will also read through your link...so far very challenging.
Hey Grumpy_Mike.
I tried creating a schematic. This is the core of the project. There is more to add, but nothing currently hooked up. FAKECRT.pdf (12.7 KB)
Please keep in mind, I am not sure which side of the symbols get wired where. Still learning. BUT in general maybe this helps?
That's your problem right there!
Without a current limiting resistor it could draw several amps.
With LEDs and LASERs you always need something to limit the current.
Your LASER symbol is backwards and the 2N2222 should have a resistor in the base circuit.
Laser Pointers and Diode Laser Modules - The Low Stress Approach
Where what you really want is a working visible diode laser, a commercial laser pointer or diode laser module may be the best option. Both of these include the driver circuit and will run off of unregulated low voltage DC. While the cost may be somewhat higher than that of a bare laser diode, the much reduced risk of blowout and built-in optics may be well worth the added cost. It doesn't take too many fried laser diodes to make up this cost difference!
Believe me, it can get to be really frustrating very quickly blowing expensive laser diodes especially if you don't really know why they failed. This will be particularly true where the specifications of the laser diode and/or driver circuit are not entirely known - as is often the case. Helium-neon lasers are much more forgiving!
Buy one that accepts an unregulated input voltage. Otherwise, you can still have problems even if you run the device from a regulated power supply. All laser pointers and most (but not all) modules will be of this type. However, if you get a deal that is too good to be true, corners may have been cut. A proper drive circuit will be more than a resistor and a couple of capacitors!
To confirm that the driver is regulating, start with an input near the bottom of the claimed voltage range and increase it slowly. The brightness of your laser diode should be rock solid. If it continues to increase even within the supposedly acceptable range of input voltage, something is wrong with either the laser diode (it is incompatible with the driver or damaged) or driver (it actually requires a regulated input or is incorrectly set up for the laser diode you are using). Stop right here and rectify the situation before you blow (yet another) laser diode!
See the chapter: Laser and Parts Sources for a number of suppliers of both diode laser pointers and diode laser modules.
If you still aren't convinced that someone else should deal with laser diode drive design issues, the remainder of this chapter provides suggestions for integrated drive chips, sample circuits, and complete power supply schematics. But don't complain that you haven't been warned of the sensitive nature of laser diodes.
Power Regulators in Laser Pointers
The following four possibilities exist for the laser diode drivers inside laser pointers. (Unless otherwise noted, this applies to red laser pointers, not the DPSS green types with their high power laser diode pump requirements.)
Series resistor: There is no active regulator. A resistor limits current to a safe value with a fresh set of batteries. The laser diode is driven like an LED. As the batteries are drained, current decreases proportional to the difference between the battery voltage and the diode drop (about 2 V) divided by the resistances. Since output power and thus brightness would also decline dramatically with battery use, this approach is only found in the cheapest of laser pointers. See the section: Laser Pointer with a Resistor for a Regulator.
Constant current: Laser diode current is set to a safe value between threshold and maximum. This takes care of battery voltage variations but still would have problems with changes in the laser diode output with temperature. This is rarely, if ever, found on red laser pointers but is used for green laser pointers since the high power pump diodes for the DPSS laser module do not have or need optical feedback for adequate regulation.
Optical feedback - unregulated reference: Some laser diode drivers use the monitor photodiode to control laser diode current but do not have constant voltage source like a zener diode circuit to use as a reference. This is fairly safe for the laser diode as long as the correct battery types are used. For these, output brightness will vary somewhat with battery voltage and will thus decline as the batteries are drained.
Optical feedback - regulated reference: The best designs (and all those using IC driver chips) will maintain nearly constant output power until the batteries are nearly exhausted.
I'd expect to only see (3) and (4) in modern red laser pointers with (4) predominating in more modern designs. Expect (2) in green DPSS laser pointers (but many or most of these will also be pulsed).
Jim-P, I may not have done the schematic correctly, not familiar with the symbols to know where to connect my lines, but in reality have them hooked up "correctly" at least they are illuminating and on/off correctly through the transistor.
Grumpy_Mike, I most certainly read it now. I had the page pinned in my tabs, but did not get a chance to fully read through it.
The laser we are using comes from a pen...and has a couple resistors a cap or two a button and a inductor on it. So I believe it has a driver circuit with limiting resistor already installed.
I will dig the other identical pen out and look at it since this one is difficult to pull out now that it is installed.
My son, Kai, and myself would like to say thanks. After reading and listening to you all, a current limiting resistor worked the trick. Installed a 50ohm, the brightness is only slightly less bright...but the temps are now maxing at 140ish, which will work just fine.
I also hardwired/soldered the transistor and resistors in place and removed the dupont connectors for that laser. It is just perfect.
I am so thrilled. If you count the 3D printing, and all the other stuff involved in this project we have around 30 hours in the build, not counting about 20 hours of trouble shooting.
We are loading the code for wave forms and such on the ESP32 as I type...this will allow us to remote control the cursor/laser and draw shapes remotely...
Technically it can act as some really bad quality oscilloscope but...I would not try using it as a actual tool...lol.
