Interesting result from adjusting a power supply

[DZ]

Ok, so last night I was testing a laser that's rated for 150mW, I set the modulation line to 5V and measured the output of the laser at about 130mW after warming up a bit. At first, I thought maybe the laser is just getting old and loosing power, then I decided to check the supply voltage. When the supply was under load, it dropped down to 4.85VDC. So I decided to adjust the pot on the switching suppy to bump up the voltage. Now, the unloaded voltage is 5.18VDC and the loaded voltage is 5.05VDC. I checked it with the meter again and was surprised to find the output of the laser settled around 180mW after warming up. Maybe it was a fluke, but I found the result surprising. I don't advocate anyone adjusting the output of thier laser power supply as it could have a negative effect, so if you do, do so at your own risk!

[ElektroFreak]

What make was the laser?

[DZ]

Ah, forgot to add that, it's a lasever. Nearly 4 years old now.

[Things]

Interesting. The PSU must be seperate though, all the lasers I have have embedded PSU, I wouldn't be brave enough to touch any random potentiometer in there without knowing what it does.

[buffo]

Hey David;

I thought your projector used a common 5 volt PSU to supply all the lasers via a common rail... Did you pull one of the lasever lasers out and hook it up to it's original factory PSU to test this? Or was your main PSU (that powers everything) the one that was dropping low?

Adam

[-bart-]

Makes you wonder what the power supply rejection ratio is of diode drivers in general

[mixedgas]

Makes you wonder what the power supply rejection ratio is of diode drivers in general

Also makes you wonder how much the low cost switchers are I. undersized II underspeced III. poor quality control.. Its scary that the PSU was underrated.. This NEEDs to be a sticky.....

People are always looking for sly ways to control/cheat on costs.....

Steve

[shrad]

care has to be taken when buying a switching PSU, as certain types of topologies may lead to cascade short-circuits in components and massive high voltage at the output (read sams repair faq about SMPS, you will scream on the cheap designs)

you certainly don't want your laser to embrace rectified mains, isn't it?