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# Question about analog modulation on a lab laser

#### sopark4000

##### New member
Ok I just recently purchased an 1,800mW 532nm lab laser from Meierlight.com and the analog modulation works by connecting 5V to input wires so 5V equals max power, 2.5V equals half power and 0V equals off. What I'm wondering is how many amps will this wire be able to handle because I actually have a very small variable voltage power supply that can output 0-15V at a constant 1Amp. Do I need lower current, is that 1Amp going to be too much power? I tried checking there website and asking them and unfortunately there english isn't great. All help is appreciated.

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#### ElektroFreak

##### New member
The modulation input requires negligible current, only voltage. In other words you can use very small wire for modulation.

#### Elektrotechniker

##### New member
Modulation only draws a few mA.
The psu you got is a variable voltage power supply that can provide a max of 1 A as you said.
The modulation will draw as much current as it needs, thus those few mA.
As long as you keep the psu's output voltage between 0-5 V it will be just fine.
Don't try it yet though. This is that's a logical way to see it, but I may be totally wrong, as I haven't tried modulating a dpss via a psu before.

EDIT: EF beat me to it.

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#### sopark4000

##### New member
Ok thanks for the info guys. I'll do some testing with a multimeter and a test load just to make sure that It is only supplying low current and not 1A. I was just worried that wether it was set to 1V or 15V that it would give a constant 1A.

#### Bluefan

##### New member
U = I*R

The modulation input is VERY likely high impedance, so a high R. I'd guess 1k or higher. Take a fixed input voltage U and the current I flowing will be low. It's very much impossible to have a huge current at a low voltage with a high resistance load. If you want to have 1A into 1kohm you'll need 1000V. Not gonna happen spontaneously.