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A-140, M-140 and multimeter

MrSnaKe

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Hello

I have chines laser driver this one (12V TTL 1W 2W 3W 445nm 450nm Laser Diode LD Driver Power Supply Stage Light | eBay)

and blue laser diode from DTR's Laser Shop A-140 and M-140

For calibrating laser driver I connected in parallel laser diode and my multimeter Uni-T UTM171B and after that my laser light but no burn

When I change from V to A on my multimeter - I have around 1,9A but laser diode not burn

As I have at this moment three diode with same problem - I suspect laser diode and multimeter not compatible at the same time?

And one more question
Calibration Voltage I can without connecting a laser diode but with Amps - its a little bit problem
I have BlackBuck 8M and NUMB44 diode if I'll try calibrate with multimeter - i received one more broken laser diode?
 



diachi

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Have you focused the laser beam to a point?

Can you post some pictures of your setup? Pictures of how you have the multimeter connected would help...
 

WizardG

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You need a test load. Connect your multimeter in series between the test load and the driver to set the desired current.
 

paul1598419

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You need to set the current on these drivers using a dummy load to take the place of the laser diode. You can use 6 1000 PRV 2 amp diodes in series, anode to cathode and at the last cathode connect a 1 ohm 3 to 5 watt resistor. Use it as the resistor going to the negative driver output and the anode of the last diode as the positive side. Measure the voltage drop across the resistor and it will be equal to the current in amps. The you can set the current on the driver for 1.8 amps for the M140 or 1.3 to 1.5 amps for the A140. This is the only proper way to set these up.
 

diachi

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You need a test load. Connect your multimeter in series between the test load and the driver to set the desired current.
You need to set the current on these drivers using a dummy load to take the place of the laser diode. You can use 6 1000 PRV 2 amp diodes in series, anode to cathode and at the last cathode connect a 1 ohm 3 to 5 watt resistor. Use it as the resistor going to the negative driver output and the anode of the last diode as the positive side. Measure the voltage drop across the resistor and it will be equal to the current in amps. The you can set the current on the driver for 1.8 amps for the M140 or 1.3 to 1.5 amps for the A140. This is the only proper way to set these up.

These guys are correct, this is the right way to do it.

I'm still curious about how you're hooking up the multimeter though... Hooking it up in parallel and setting it to measure current is going to make screwy things happen...

I'm assuming you got a module for the diode and aren't just running the bare diode... You'll need to adjust the focusing lens to make the beam a fine point for best burning once you have the current set properly.
 

MrSnaKe

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Hello

I known a difference to hooking up the multimeter for Volt and Amp

Check photo - https://drive.google.com/drive/folders/0B4hCH8A0_bH-WGYtdk16cU5zUkU?usp=sharing

Amp 1-3 jpg - hooking up the multimeter for Amps

Volt 1-4 jpg - hooking up the multimeter for Volts

lps 1-3 jpg - with laboratory power supply

result.jpg - what happened with plywood after turned on A-140 blue diode laser with 80% of power during 1-2 min (as you can see - nothing)

Focus are ok as you can see on the result.jpg some engraving what I was made few hours before connect multimeter

Multimeter connection
Volt - parallel connections
Amps - break (gap) connections

Laser diode stops burn after connect multimeter in Volt mode not Amps.
Based on the fact that this is the third laser diode - problem are not in wrong connection, any ideas?
 

WizardG

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Hmmm, so you're using the bench supply to feed the laser directly and not using a driver? It's possible your power supply has damaged your diode(s) with turn on voltage spikes or something similar.

I see the driver in the photos but it looks like you've bypassed for some of the measurements.
 
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diachi

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Good good, just checking you knew how to hook that up properly. Not everyone does...


So it was working fine before then stopped? Looks plenty bright enough in the pictures, although that's never a good way to judge actual output power. Would be handy if you had a laser power meter. Sounds like you know how to focus it just fine, so it isn't that.

How does the lens look? Is there any junk cooked into it? Could be residue has built up from past engraving and has resulted in the lens getting a little cooked, reducing output power. Could also be the LD has dropped in output for whatever reason, low quality driver maybe?
 

MrSnaKe

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Hmmm, so you're using the bench supply to feed the laser directly and not using a driver? It's possible your power supply has damaged your diode(s) with turn on voltage spikes or something similar.

I see the driver in the photos but it looks like you've bypassed for some of the measurements.
Its not possible, I connect diode via driver, engraving few days maybe 5 hours in total for test after that I connect a multimeter to check the Volts and Amps and at that moment my diode stop fire. Laboratory power supply I connect just for additional test.

Problem happened when I connect multimeter for configure driver but I dont understand why diode stop fire when I try to check the Volts (not Amps)
 

MrSnaKe

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Good good, just checking you knew how to hook that up properly. Not everyone does...


So it was working fine before then stopped? Looks plenty bright enough in the pictures, although that's never a good way to judge actual output power. Would be handy if you had a laser power meter. Sounds like you know how to focus it just fine, so it isn't that.

How does the lens look? Is there any junk cooked into it? Could be residue has built up from past engraving and has resulted in the lens getting a little cooked, reducing output power. Could also be the LD has dropped in output for whatever reason, low quality driver maybe?
Yes everything was OK till I connect multimeter.
check https://drive.google.com/drive/folders/0B4hCH8A0_bH-WGYtdk16cU5zUkU?usp=sharing

file engraving.jpg

At this moment I didnot have laser power meter but today I try to assemble diy laser power meter according to this
Laser Kids - How to measure power of a laser pointer at home

According to low quality, I have last A-140 (photo A-140.jpg) and later I replace but I overconfident that everything will be nice till moment when I connect multimeter.

About lens I also have a backup lens. Of course I replace but problem still alive

Photo my backup lens
numb44_2.jpg
numb44.jpg
 




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