Voltage doubth with FET/lm358

I have just received an order from odic lasers containing 1 m140 blue and 1 635@300mw mitsu. And 2 FET/lm358 drivers.

The drivers have 1.5v dropout. The idea is feed them with a 12v supply. I have the dummy load, all the wired pads but Im stuck in the doubth... do I have to supply just 1.5v above the diodes operating oltage, or the driver will reduce the voltage too?

This is my first high power buildings, the first time Im going to see the 450 and 638 coherent wavelenghts and Im a mix of superexcited to see it, and afraid to fried them... Help that newbie!!

You need to provide at least Vf_diode + 1.5V to the driver; however, the drivers will usually drop (absorb) whatever excess voltage there is above what is needed. In other words, you can have more voltage than is needed and your driver will prevent that from becoming a problem.

Still, you ought to try and keep the input voltage as close to the minimum needed (e.g. Vf_diode + 1.5V) because excess voltage will cause greater heating of your driver.

Before you hook up, run through a check-list:

1. Use a dummy-load to pre-determine how much current the driver is producing before hooking up your laser diode.
2. Have adequate heatsinking on the laser diode. This means more than just the aixiz module: a real heat-sink.
3. With the power off, short the output of the driver before you solder up the leads to your laser diode. This prevents any stray charge from potentially zapping your laser diode.

Thank you for put it clear, Bionic. :beer:

The 635 is lasing strong at 300mw and have huge wings that I´ll try to cut without lenses. Tomorrow I´ll go for the M140 :eg: