M140: Powering with USB?

[TimTom]

Hi guys,

today I got the idea to power up a M140 diode with a USB from my pc, because I don't have a driver atm. that is working and I want some fun with my lazor's.

I heard, that they give me about 500mA up to 1,5A. Is it true, if yes, useful or possible for the diode?

Would be cool ^-^

Thank you,

Tim

 

[jimdt7]

That's not a good idea nor for the PC nor for the diode...it could damage both! :beer:
I suggest you buy a boost driver if you plan to power your diode from a USB port!

Jim

 

[ARG]

You can't hook it up directly as USB is constant voltage and you need constant current.

 

[TimTom]

okay, good to know - thank you!

 

[LarryDFW]

TimTom;

In spite of the comments, your diode can be hooked up directly to a USB voltage source.

1. You must have the diode in a good heat sink.

2. Then you must check the current when hooked up to your 5 VDC USB port (they will vary) If current is too high for the diode, then you will need a resistor to lower the current.

I have a 445nm diode hooked up to a new 4.35 VDC lithium cell for a direct drive @ 700ma. It has been operated that way for over 1 year.

http://laserpointerforums.com/f65/direct-drive-445-host-52918.html

LarryDFW

 

[ARG]

In spite of the comments, your diode can be hooked up directly to a USB voltage source.

1. You must have the diode in a good heat sink.

2. Then you must check the current when hooked up to your 5 VDC USB port (they will vary) If current is too high for the diode, then you will need a resistor to lower the current.

I have a 445nm diode hooked up to a new 4.35 VDC lithium cell for a direct drive @ 700ma. It has been operated that way for over 1 year.

Just because something can be done does not mean it's a good idea
If you must hook up the diode directly to a voltage source at least use a resistor to drop the excess voltage, 5V is too high for an M140.

 

[chipdouglas]

and this is why we have dialog. whether some thing is safe or not is now up to the op to decide =p

 

[jimdt7]

I once tried powering my A-140 straight from a 9V battery....it WORKED! (for a week) :shhh:

Jim

 

[NKO29]

I have powered a 300mW red off of USB WITH DRIVER just fine However you'd probably want a high end desktop motherboard to do higher currents.

 

[BShanahan14rulz]

At 5V, the M140 would allow ~3.5-4A, which is too much for this little beastie, and definitely would either trip a temporary fuse on your computer or just burn up that USB port. Visually extrapolated from this graph: http://cms.diodenring.de/images/stories/electronic/laser_diode/diode_1-3_voltage.png


A blu-ray diode is a different story, with a higher Vf range within which 5V falls fairly comfortably.

I have an A140 build (well, I used to, can't find it right now ) that is direct driven from an 18650, but even at 4.2V, a typical 445nm diode will only allow ~800mA, which is easy peasy for an 18650.

 

[LarryDFW]

If you must hook up the diode directly to a voltage source at least use a resistor to drop the excess voltage, 5V is too high for an M140.

It depends on the source of the USB power and the wiring.

Most USB sources will sag ~ 1/2 volt under that load (several amps).

My 445nm direct drive runs @ 4.4 VDC and only delivers 650 ma.

A 0.22 ohm resistor would be a good idea, to test the current with.

LarryDFW