532nm Driver

I haven't followed the entirety of this thread, but I think there is one point that probably needs to be made:

- Unless you have a really good reason to want to replace a DPSS module's driver, diode, or both, don't bother.

What's the reason for doing so? When I've replaced a DPSS module driver, it has generally been for some purpose that made it a necessity. IE, input power source, or space considerations. If you don't need to replace the driver for some reason, don't.

The same is even more so the case with the diode. Why on earth would you want to swap diodes if you didn't need to? If your notion is that a 5mW pointer can just take on a 600mW IR diode and suddenly output 150mW of 532, it doesn't work like that. Other things (like the crystals etc) need to scale up in quality also. You're not going to buy a $8 5mW module, add a $5 600mW IR diode, and have a 200mW green module for $13 that would have otherwise cost $50.

So my question, is "why" ?

rhd,

I just wanted to put together my own driver for fun and for low cost. I already have shitty red ones, so didn't want to do one of those. Hence why I chose green. I just wasn't familiar with how different green are from the other lasers (dpss over diode). It was when other people started throwing out I should swap the diode that I got pretty confused.

SO. I am going to copy this DDL driver. My original question was do I need different resistors or capacitor for a 532nm dpss. Obviously, that is not entirely how the thread progressed

Will this DDL driver work for both the 10mw and the "200" mw one (closer to 140)? I am trying to understand the math behind the driver.... its the components like the pot and capacitor that throws it off for me.

I would probably ignore the suggestion that swapping the diode is worth doing here.

This driver will work for any diode - 405,445,635,808, etc. Your capacitor can stay the same. I would get rid of the pot all together. JUST use a single resistor to set the current permanently.

1) Measure the current going to the diode from the stock driver

2) Compute the equation: 1250 / StockDriverCurrent (in mA)
* So if the stock driver is 250mA, your equation would be: 1250 / 250 = 5

3) This is the Ohm rating you want your resistor to be (5 Ohms in the example above)

4) This isn't as important, but you should also compute the equation: 1.25 x StockDriverCurrent
* Continuing the example above, your equation would be: 1.25 x 250 = 321.5

5) This is the mW rating you want your resistor to be. (312.5mW or ~0.3W in the example above). Round up, so go with a 1/2W or higher resistor in this example.

That's it.

Start with bluray or true blue before moving up to -dpss lasers.

Thanks again rhd! One last question: What if I want the driver to be a higher current? How do I know what the diode can take?

Calarin said:

Thanks again rhd! One last question: What if I want the driver to be a higher current? How do I know what the diode can take?

Click to expand...

In this case, you don't really.

Calarin said:

Thanks again rhd! One last question: What if I want the driver to be a higher current? How do I know what the diode can take?

Click to expand...

Usually you look at the diode specification sheet published by the diode manufacturer. As RHD said we can't in this case.
Or, in the case of harvested diodes, we have extensively tested many red, IR, blue, and bluray diodes here at LPF, and have determined the min/optimum/max currents to run them.

If you buy this 200mW module at DX, you will get a 50mW one with crappy cristals and just a 500mW 5.6mm IR diode that is pressfitted. Real 200mW modules are using 9mm 1000mW IR diodes that are screwed at the back.

There is also no need to replace the driver. This OpAmp based driver is even better than a LM317 based driver. All the modules are using the same driver. You can even push it up to 1.2A with a IR diode that is capable in taking that much current. Just will need the transistor to be heatsinked.

Oh well some "real" 5- 50mW modules are also using this driver with just a smaller sense resistor.

All in all you better do not replace the driver and also do not buy such a module at DealExtreme. There are much better sources where you get a up to spec module.

honeyx said:

If you buy this 200mW module at DX, you will get a 50mW one with crappy cristals and just a 500mW 5.6mm IR diode that is pressfitted. Real 200mW modules are using 9mm 1000mW IR diodes that are screwed at the back.

Click to expand...

I'll agree with you on the crystals and power, but there's no reason to believe "screw" mounting is better than press-fitted, or that a diode in a 9mm can is better than the same diode in a 5.6mm can. At least not in any substantial way.

I didn´t say screw mounting is better than press-fitted. It may even be worse if the ring is not screwed well allowing the diode to rotate. It also does not matter which kind of can. It may be even a c-mount like used in the old greenies. It´s just afaik there is no 1W IR diode in a 5.6mm can aviable. That´s why they are using 9mm 1W diodes in the new 150 and 200mW modules.