Green pumped laser diode - 20 volts?!

[SarahC]

I took apart a cheap laser disco light, & hooked my oscilloscope up to the green diode... 20 volts! NO type of power wave, down to 5 microseconds.

I noticed the green laser module only has power leads - the photo-resistor isn't connected.

So I'm thinking - perhaps it's using 20 volts, and about 5 milliamps (I haven't checked the actual ampage yet) - as a safe way of powering the laser without blowing it?

I've read green laser modules (no driver) take around, roughly 4 volts, and several milliamps usually.

Does anyone have any experience or thoughts on this?

:thanks:

 

[Fiddy]

got pics?

 

[Cyparagon]

You probably have the attenuation set to x10, and the actual diode voltage is 2V. Measure a known voltage to be sure.

 

[SarahC]

Fiddy, Cyparagon - I'm going to bed now, but I'll check both in the morning!

Thanks for the sanity-check. I didn't check the attenuation of my probe!

 

[Cyparagon]

Oh, by the way, you won't see any variation as laser diodes are DC devices. A simple multimeter will suffice for most any measurements you want to make.

 

[SarahC]

Cyparagon: Thanks, you were right. I should check the switch in the future, it was 2.65 volts after I took a proper reading.

>you won't see any variation as laser diodes are DC devices.

I thought some of them could be run by a pulsed square wave? This one wasn't though, but the powers all noisy... yuck.

 

[Fiddy]

pusled square wave is still DC! your just changing the duty cycle.

 

[Cyparagon]

Yes, you can analog or pulse width modulate them, but you won't find something like that in a static system like a pointer or a "disco light."

 

[Fiddy]

Good call.