Old 03-08-2012, 07:22 PM #1
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Default Function Generator as power supply?

Hey,

I'm a sophomore in college and I'm working on a DIY blue laser (440nm I believe), sitting on a breadboard for now. Since it's relatively high powered, I'm going to want to run it at around 1A, I'll need about 9V for the driver I'm using, etc. cookie cutter blue. The driver will be a very simple LM317 driver with a fixed current for now (basic DDL driver I think, it's what I have components for haha).

Since I'm too lazy to buy batteries that can run it well (9 volts barely get it to laze due to lack of current), how reasonable would it be to use a function generator (We have a ton of stuff in our Analog Electronics class lab) to power the laser? I'm not too positive on the calculations which is why I'm asking on here, but could I hook my laser driver up to a circuit with a full wave rectifier bridge and get the steady voltage and current that I need? My main concerns are ripple (unless a square wave could get rid of that?) and current requirements.

I have been trying to run this on Orcad/Pspice, but I have no idea what I would use to simulate the laser diode or LM317, so if anybody has any input or ideas before I try to grind through these calculations I would love to hear

Thanks for any help
Abray


P.S. Sorry if this is in the wrong section, I didn't know if it should belong here or in the experiments and modifications section.


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Old 03-08-2012, 07:39 PM #2
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Default Re: Function Generator as power supply?

Overload the output stage and function generator stop generating, then go BOOM.
Use a doorbell transformer, or an Air Conditioner control circuit transformer, and stop abusing the school's test quipment.......
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Old 03-08-2012, 07:49 PM #3
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Default Re: Function Generator as power supply?

Yeah, that's a terrible idea. Your lab will have a bench power supply - use that.
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Old 03-08-2012, 07:58 PM #4
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Default Re: Function Generator as power supply?

I haven't even used it yet....and thanks to your answer, I most likely won't be. I had noticed the DC power supplies definitely could not supply enough current, but when I asked the lab prof if they had any equipment that could generate enough voltage and current, he said yes. Maybe I'll just have to email him or talk to him about what I'm doing, and he'll know if they have something that will work.

But about that doorbell transformer, I'll have to look into that. I googled one quick and it said 30 Watt 16 V. That's plenty.

EDIT
Cyparagon: That is probably exactly what my professor was thinking about. I'll definitely email him or go talk to him about it.

Last edited by Abray; 03-08-2012 at 08:01 PM.
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Old 03-08-2012, 10:08 PM #5
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Default Re: Function Generator as power supply?

If you decide to get something for outside the lab, don't get a doorbell transformer. It's large, inefficient, less safe, and requires more components and assembly. Get something like this instead.
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