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That was exactly why I put it there, to drop voltage. I put the MOSFET there to act as a variable resistor, just like when you'd put a POT in there, to act as a current dial. (So NOT like a switch) The MOSFET will thus be used in it's linear part of the characteristic. It looks like you...

First of all, thanks for all the effort and suggestions! But I'm going to come in between your calculation battle for a moment now, to clear out some misunderstandings. Also, I don't think using 14 350mA regulators is a good idea. It might work, but .. .seriously? that's ridiculous.. The laser...

It would also be great if I could control the current trough Arduino. All I can come up with are these two possibilities: A digitally controlled potentiometer, but I can't seem to find low resistance values (below 1ohm) or high power (above 5W) so I don't think this will be an option. My...

I was also planning on adding a MOSFET in front of the regulator. But for the current sensing, what kind of IC do you suggest? Is the LT6105 - Precision, Rail-to-Rail Input Current Sense Amplifier - Linear Technology good for this application? And how will I get the current monitor to create a...

Hello, I want to create a linear current regulator for this IR diode: http://www.eqphotonics.de/cms/cms/upload/datasheets/WSLD-808-005-3.pdf It's a 5W diode, operating at 2.0V at about 5A. I'd like to make use of a linear regulator, powered by a 5V, 8A switched mode power supply. (link) The...

Ok thanks. Selling fake eye protection is so ethically wrong; Who does that :S

Even at almost 0 output, most of the light goes right through. I don't mean it gets brighter going trough, but the part that does go trough, is brighter than the reflected part.

Hello, I recently ordered laser safety glasses on Ebay for my red 635nm laser. (this one) But when I shine the laser trough the glasses, the light that comes out is Brighter than the reflected light. ?! this means that more light passes trough than gets blocked. The dot is still so bright...

Oh like that! So to choose the output current, I simply change the sensing resistor into a POT? (however I'm not sure there are like 0.1ohm pots) EDIT: I calculated the sensing pot, and would have to be a 5or10ohm pot. And indeed.. That is way too expensive. I was thinking about €5 or...

Ooooh so the FB resistor that you must add, creates a voltage divider together with the 499k resistor? Is it still possible then to have the output of the OpAmp connected to this pin? Because that would mean that the OpAmp output is connected to Vout trough the 499k resistor. Isn't that bad?

So I need to amplify the current signal from a sense resistor, into a resistive value? It would be a lot easier if the fb was an analog voltage input.

http://www.linear.com/product/LT3517 This is probably something I'm looking for, but it does not have an internal switch. Also, why are these packages so tiny? 4mm wide?! how am I supposed to solder this, my soldering iron tip is like 5mm wide. Linear Technology - Parametric Search for...

Alright, forget the 'no inductor' requirement. I've also found a lot of ICs with built in inductors, which do go up to high currents such as 1-2A! Fantastic ^^ Now the problem still remains: they are voltage regulators?! About the different packages: It seems like the larger packages such as...

Hello, I was scouting Linear Technology's ICs to find a switching regulator which regulates the output current, as required for laser diode drivers. (alternative: Maxim Integrated) Preferably I want a regulator which doesn't need an inductor to operate. I read that charge pumps might be what...

@blord: 200mW won't be enough. I want to make a laser that has a visible beam in daylight conditions. The diode I'm using now is getting very close to my satisfaction but I'd like to get some more out of it. @cheech226: I'm using the standard lens that came with the aixiz module. I'm quite sure...

Alright, thanks! I learned a lot from this ^^ Another question: What do you think the limit of this diode would be? I'm quite new to lasers, and very unsure when it comes to trying out what I can get from a diode. In the datasheet, the maximum current is stated 400mA, which is also the current...

Thanks for all the replies! this explains a lot. So basically I just bought a wrong diode.. I never wanted this :S How can I know this in the future? How can I see if a diode will be "unfocussable" like this? is it the "far field patterns" graphic in the datasheet page 3? Because both graphs...

hmm but what is the reason for it that I can't focus it smaller?

Hello there, Problem: I bought a Mitsubishi ML520G71 laser diode (red-orange 635nm; 300mW) but I can't seem to focus the beam to a small dot. I am aware that it's normal for the laser pattern to be a line. However it should be possible to make this line-shape very small right? (let's say at...