DC Power Supply help!

[NightExplorer96]

Hey guys,

I decided to go ahead and purchase this PS for my 532 lab. I do have a few question however:

1) This lab seems to have a particular voltage of 5V to reach the 2.5W limit it's rated at. Does every lab laser have an operating voltage of 5V's or is this set by CNI when they sell you the unit and each has a specific voltage?

2) I guess I simply need to attach the red/black cables out of the PSU of the CNI unit into the PSU of the eBay one correct? I was also told by the seller to make sure the Amps are set at 0, all the time! Any dangers if I accidentally go above 5V's?

Thanks
-Alex

 

[Cyparagon]

Not everyone has read your other threads on your green laser. Can you please provide some basic background on its power requirements?

Why have you chosen to use a bench power supply over a standard 5V supply?

I was also told by the seller to make sure the Amps are set at 0, all the time!

Either the seller is an idiot, or you misunderstood him.

 

[NightExplorer96]

Not everyone has read your other threads on your green laser. Can you please provide some basic background on its power requirements?

Why have you chosen to use a bench power supply over a standard 5V supply?



Either the seller is an idiot, or you misunderstood him.

So my particular laser is as follows so anyone helping can get a good look at what it is: http://www.cnilaser.com/PDF/MGL-F-532.pdf

Now, this particular laser is Analog and came shipped with the PSU-H-OEM power supply. The particular seller said this to me via an eBay message Cyparagon.

"Just be sure not to send it any amps at all. Amps always at 0.
But dial the voltage from 0-5V to see the beam. 5V will be full power. The power supply includes alligator clips and you just connect the back and red and that's it! That's what I use to test and evaluate any analog laser. "

-Alex

 

[Cyparagon]

Okay, so 5V is the modulation voltage, not the power input. In that case, the current should read zero, but you should NOT set the current at zero, since setting the current at zero will also sometimes set the voltage to zero, depending on how the PSU is configured and calibrated.

5V is a standard for laser modulation. I do not recall anything NOT 5V.

The input should have clamping above 5V, but you test the clamping at your own risk.

You can get 5V from an old phone charger. Using a bench supply is large, expensive, bulky, and not necessary. If you wanted power adjustment, a 10k pot (wired as a voltage devider) on the phone charger would provide the same functionality.

 

[NightExplorer96]

Okay, so 5V is the modulation voltage, not the power input. In that case, the current should read zero, but you should NOT set the current at zero, since setting the current at zero will also sometimes set the voltage to zero, depending on how the PSU is configured and calibrated.

5V is a standard for laser modulation. I do not recall anything NOT 5V.

The input should have clamping above 5V, but you test the clamping at your own risk.

You can get 5V from an old phone charger. Using a bench supply is large, expensive, bulky, and not necessary. If you wanted power adjustment, a 10k pot (wired as a voltage devider) on the phone charger would provide the same functionality.

Thanks! So I am free to set the Voltage to whichever I chose, but the Amps should not be set to 0.00?

-Alex

 

[Rivem]

Thanks! So I am free to set the Voltage to whichever I chose, but the Amps should not be set to 0.00?

-Alex

Pretty much. Basically adjust the volage with hw power supply in Constant Voltage (CV) mode. You don't set the current in this mode, the supply will compensate for the current on its own to keep a set voltage.

Otherwise, directly driving lasers from that supply, you'd use constant current (CC) mode to set a current.

You can usually set a max current in CV mode for safety, but I'm not sure that partocular supply could do it.

I'd agree with Cyp it's seruous overkill though. You could get away with something much simpler.

 

[diachi]

Thanks! So I am free to set the Voltage to whichever I chose, but the Amps should not be set to 0.00?

-Alex

Between 0V and 5V, yes, best to keep it to no more than 5V to be safe.

Yes, just leave the current setting somewhere above 0. Modulation inputs only need a few mA at most. Hell, crank it half way and leave it there.

Really though ... you'd be better using something that's 5V constant voltage with a potentiometer... hell you could throw it all in a little project box and have a sort of external controller for the power/laser enable.

Not saying don't get the bench supply either, they are super handy anyway! Which reminds me, I need to buy a couple now that I have money... been a pain in the ass not having one.

Sorry I couldn't help on Skype earlier, I had you messing me on my cellphone while I was talking on it to a colleague while also trying to fix some network issues at one of our sites.

 

[NightExplorer96]

Between 0V and 5V, yes, best to keep it to no more than 5V to be safe.

Yes, just leave the current setting somewhere above 0. Modulation inputs only need a few mA at most. Hell, crank it half way and leave it there.

Really though ... you'd be better using something that's 5V constant voltage with a potentiometer... hell you could throw it all in a little project box and have a sort of external controller for the power/laser enable.

Not saying don't get the bench supply either, they are super handy anyway! Which reminds me, I need to buy a couple now that I have money... been a pain in the ass not having one.

Sorry I couldn't help on Skype earlier, I had you messing me on my cellphone while I was talking on it to a colleague while also trying to fix some network issues at one of our sites.

Pretty much. Basically adjust the volage with hw power supply in Constant Voltage (CV) mode. You don't set the current in this mode, the supply will compensate for the current on its own to keep a set voltage.

Otherwise, directly driving lasers from that supply, you'd use constant current (CC) mode to set a current.

You can usually set a max current in CV mode for safety, but I'm not sure that partocular supply could do it.

I'd agree with Cyp it's seruous overkill though. You could get away with something much simpler.

Hello guys,

Thanks for the help! How come the seller of this laser said to keep the Amps set at 0 thought? This is just what has me confused

Also, my Aries is finally showing up after 1 month of shipping so that's good

-Alex

 

[diachi]

Hello guys,

Thanks for the help! How come the seller of this laser said to keep the Amps set at 0 thought? This is just what has me confused

Also, my Aries is finally showing up after 1 month of shipping so that's good

-Alex

The seller doesn't know what they are talking about by the sound of things, at least when it comes to modulation input...

 

[NightExplorer96]

The seller doesn't know what they are talking about by the sound of things, at least when it comes to modulation input...

Yikes. So just set it at 1 Amps or something? Is there a danger limit I shouldn't pass?

-Alex

 

[lasersbee]

The modulation input requires little current.
Just don't apply more than 5Volts.

For a test...you can use 4 rechargable 1.2V batteries
in series with a 10K pot (as Cyp mentioned). That will
give you about 5.6Volts fully charged.
Connect one side of the pot to the battery negative
of the batteries and the other side of the pot to the
Anode of a rectifier diode (1N400x) and the Cathode
of the rectifier diode to the positive of the batteries.

The pot will adjust the wiper voltage between ~0 to
~5V... between the wiper and the battery negative.
This you feed to the analog input of your Laser driver.

Don't forget to disconnect the batteries from the
circuit when done even though the battery/diode/pot
circuit only draw about 0.5 mA.


Jerry

 

[Alaskan]

You probably already know this, but just in case, never have your laser connected to the unit when turning it on, even if it was set to the proper voltage and current the last time you used it. I have one much like this and it killed a diode doing that, a voltage spike well above the voltage I had it last set for occurred when turned on. The duration of the spike was so fast the meter never showed it, but it sure killed the M140 diode I had hooked up to it. Short AC power interruptions could cause the same problem.

Edit: Even if the voltage and current are set to zero before turning the unit on, these cheap power supplies might still spike voltage through your device. Always hook the device up after the unit has been turned on and I'd recommend disconnecting your laser before turning the unit off too. After the unit is turned on, it is probably safer to turn the voltage all the way down before connecting the laser and only bring it up after it is connected, also turn the voltage all the way down before disconnecting too, after disconnected only then turn the PS off.

Regarding the CC control, when controlling the current to stay below a specific amount, what is really happening is the voltage is being limited through a feed back loop to reduce the voltage if the current goes higher than the amount you set it for, reduced just enough to bring the current back down to where you set it.

 

[NightExplorer96]

^Thanks Alaskan! I spoke to diachi and he told me the same thing. No need to kill a $1,200 laser

-Alex

 

[Alaskan]

Not hard to do, just must be mindful of the gotcha's with those types of PS. If you had an O'scope, you could test it to see how it behaves. I wanted to post the warning to save others from suffering the same problem I had.

 

[diachi]

Not hard to do, just must be mindful of the gotcha's with those types of PS. If you had an O'scope, you could test it to see how it behaves. I wanted to post the warning to save others from suffering the same problem I had.

Some of those output spikes are large enough that you can catch them with a cheap DMM - it won't give you any information about actual peak or spike duration etc, but it'll tell you that there is a spike.