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Suitable driver and enclosure for an M140?

nzoomed

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Been reading a few threads on drivers for M140 diodes and have been looking on ebay and found this:
Item number 273198784157

I have no idea on its quality, but obviously its more ideal to use a CW driver than a pulsed driver?
I probably plan to run it around 1.5-1.6W

Also saw item number 131970060841 mentioned on another thread.

Have no idea if any of these modules are CW, as the sellers dont give much in the description.

Been looking at this host here item number 261231091438 Im assuming there is no need for a crazy heatsink if you are not going to be operating it for a few seconds at a time?
Im not sure how hot this will get after say 30 seconds of operation, but most lower power lasers ive bought say to only operate for up to 30 seconds, but they dont have any heatsinks to speak of.

Other question is operating voltage and power requirements, looks like most of these drivers are boost converters, since i believe its operating voltage is around 5V (correct me if im wrong as i cant find datasheet, but believe its this voltage for most diodes)

Obviously 2x18650 in series would give longer operating time, but would require a driver with a buck converter to regulate the voltage to a lower level.
I notice most higher powered lasers use 2 or more lithium batteries, so any recommendations are appreciated.

Also trying to find a suitable enclosure to house the batteries and host.
Do most people just grab a cheap $5 laser pointer off ebay and strip it down?
Ive seen what appears people inserting the host into an old flashlight, but i guess whatever works?
What is appealing is that the drivers in those cheap lasers already have the tactile switch soldered onto the driver and then slips into the tube, would make things easier if it was possible to find a driver that was suitable that could be retrofitted into an old laser pointer..
Any suggestions are much appreciated. Ive seen some for sale on ebay with an on/off switch at the rear much like a flashlight, but i would prefer a momentary on/off switch like most pointers have on the side as its much safer.
 



thanhtung

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in here have alot of driver for laser, you can see at my sign or some famous driver from DTR, SL, Astra with suiable current is 1.6-1.8A for your diode
 

nzoomed

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in here have alot of driver for laser, you can see at my sign or some famous driver from DTR, SL, Astra with suiable current is 1.6-1.8A for your diode
are these drivers continuous wave or pulsed drivers?
Any form of current regulation?
 

Immo1282

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Hi - All the drivers that DTR sells, the Astral Drivers etc. are all current-regulated drivers. You need a current regulated driver else your laser diode will not survive. Drivers designed for handheld lasers (i.e. all of the above) are all CW, a pulsed laser will be very unsatisfactory as a handheld.

Check the Buy/Sell/For Sale subforum - a good range of custom made hosts, or modded flashlight hosts can be found there for sale from a range of forum members; Look for Lifetime17, Trinh Hong Phuoc and others.

Gutting a cheap laser and using the host is not generally reccomended as it can be a giant pain, as the manufacturers of those hosts often use glues and epoxy which makes their dissassembly difficult.
 
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nzoomed

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Hi - All the drivers that DTR sells, the Astral Drivers etc. are all current-regulated drivers. You need a current regulated driver else your laser diode will not survive. Drivers designed for handheld lasers (i.e. all of the above) are all CW, a pulsed laser will be very unsatisfactory as a handheld.

Check the Buy/Sell/For Sale subforum - a good range of custom made hosts, or modded flashlight hosts can be found there for sale from a range of forum members; Look for Lifetime17, Trinh Hong Phuoc and others.

Gutting a cheap laser and using the host is not generally reccomended as it can be a giant pain, as the manufacturers of those hosts often use glues and epoxy which makes their dissassembly difficult.
OK, thats helpful thanks, ill check those guys out.
I was asking about CW because i know alot of the cheap chinese lasers are usually pulsed, so im skeptical on what im getting off ebay sometimes.
Would you recommend a single 18650 in this configuration, or should i look at going with 2 of them in series?
 

Immo1282

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Your battery configuration is a choice you should make based on the size of host you want - If you use a single cell, you will need to use a boost driver (will be current regulated, but the operating voltage of an m140 is above 3.7V, so you need to boost this). If you use two cells, you should use a buck driver (or Linear type driver). Switching drivers (boost/buck/buck-boost/SEPIC etc) are more efficient, but cost more and are more complex. Linear drivers waste a good deal more power, but are generally far cheaper.

Not sure where you read that most of the cheap lasers were pulsed - that's extra complexity that they simply don't add, nor would be a good idea. Pulsed lasers are used where you want a very short, very energetic pulse of light instead of a continuous beam. No handhelds I'm aware of do this.
 

nzoomed

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Your battery configuration is a choice you should make based on the size of host you want - If you use a single cell, you will need to use a boost driver (will be current regulated, but the operating voltage of an m140 is above 3.7V, so you need to boost this). If you use two cells, you should use a buck driver (or Linear type driver). Switching drivers (boost/buck/buck-boost/SEPIC etc) are more efficient, but cost more and are more complex. Linear drivers waste a good deal more power, but are generally far cheaper.

Not sure where you read that most of the cheap lasers were pulsed - that's extra complexity that they simply don't add, nor would be a good idea. Pulsed lasers are used where you want a very short, very energetic pulse of light instead of a continuous beam. No handhelds I'm aware of do this.
Ive had cheap laser pointers many years ago where they would pulse the diodes at higher power to make them more powerful than the specs of the diode without killing it, thats how i understand it anyway.
Maybe it was more cost effective for those cheap lasers 10 or so years ago when the diodes were more expensive?
IDK, but i remember reading how to check if it was pulsed and all you had to do was move it fast in a line or circle and you could usually see breaks in your drawing on the wall.
This is what i found with my first cheap laser back in the day, i since found one later that was not pulsed.
Im thinking i will go with a buck driver with 2 cells. I dont think the operating time off a single 18650 would be overly long.
 

GSS

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Ive had cheap laser pointers many years ago where they would pulse the diodes at higher power to make them more powerful than the specs of the diode without killing it, thats how i understand it anyway.
Maybe it was more cost effective for those cheap lasers 10 or so years ago when the diodes were more expensive?
IDK, but i remember reading how to check if it was pulsed and all you had to do was move it fast in a line or circle and you could usually see breaks in your drawing on the wall.
This is what i found with my first cheap laser back in the day, i since found one later that was not pulsed.
Im thinking i will go with a buck driver with 2 cells. I dont think the operating time off a single 18650 would be overly long.
Are you sure your not confusing a pulsed driven laser with a DPSS 532 with it's unstable fluxuating beam?
 

Immo1282

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Your duty cycle due to overheating will almost certainly be far shorter than the battery life with an M140 diode - you can do a rough ball-park calculation to figure out the battery life by calculating the capacity of a battery in watt-hours and then finding the power consumption of the laser.

The capacity of a typical 18650 cell is for arguments sake 2500mAh, Using a nominal voltage of 4.2V, this gives us 10.5Wh of energy total. i.e. in ideal circumstances, the battery will deliver 10.5W of power for one hour, or 21W for 30 minutes etc.

I haven't measured the current drawn from source of a boost laser driver set up for an m140, but let's assume worst case that the driver draws 3A from the battery for an output current of 2A. This feels to me like a conservative estimate, to bake in other losses and non-idealities such as reduced operating temperature for the battery.

So using 3A @ 4.2V, the power consumed is around 12.6W. That's a runtime of 0.83 hours (or around 50 minutes) on one charge. No reasonably compact handheld laser without active cooling is going to run for that duration without overheating and the diode burning out.

You are going to have to wait for the laser's heatsink to cool down several times within the lifespan of one charged 18650 cell. And the off-time in the duty cycle is going to be long enough that it will give you time to swap the battery.
 

nzoomed

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Are you sure your not confusing a pulsed driven laser with a DPSS 532 with it's unstable fluxuating beam?
Perhaps i am thinking of something entirely different, basically these cheaper pointers would turn the diode on and off many times a second in pulses, but at a higher voltage than what the diode specs were if it was left on continuous.
 

GSS

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I wouldn't think on a cheap laser. Was the laser a green one?
 

nzoomed

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Your duty cycle due to overheating will almost certainly be far shorter than the battery life with an M140 diode - you can do a rough ball-park calculation to figure out the battery life by calculating the capacity of a battery in watt-hours and then finding the power consumption of the laser.

The capacity of a typical 18650 cell is for arguments sake 2500mAh, Using a nominal voltage of 4.2V, this gives us 10.5Wh of energy total. i.e. in ideal circumstances, the battery will deliver 10.5W of power for one hour, or 21W for 30 minutes etc.

I haven't measured the current drawn from source of a boost laser driver set up for an m140, but let's assume worst case that the driver draws 3A from the battery for an output current of 2A. This feels to me like a conservative estimate, to bake in other losses and non-idealities such as reduced operating temperature for the battery.

So using 3A @ 4.2V, the power consumed is around 12.6W. That's a runtime of 0.83 hours (or around 50 minutes) on one charge. No reasonably compact handheld laser without active cooling is going to run for that duration without overheating and the diode burning out.

You are going to have to wait for the laser's heatsink to cool down several times within the lifespan of one charged 18650 cell. And the off-time in the duty cycle is going to be long enough that it will give you time to swap the battery.
Yes, ive been doing some calcs, and for most high end 18650 cells, you would get that much operation easily.
I just see a fair few lasers that are less powerful that run on 2 18650 cells, and not sure the exact reasons why.

Regarding overheating, im not sure how long is the ideal operation time with no active cooling, i guess this is where a decent heatsink comes in. Even my 50mw laser with no heatsink says operate no more than 30 seconds at a time.
 




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