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PC PSU into a Lab PSU

LaZeRz

LaZeRz

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Wait a sec

Why are lm350's like 5 times the price of lm317's?

Is that normal or just my local electronics store raising prices ridiculously high?
 





Asherz

Asherz

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LaZeRz said:
Wait a sec

Why are lm350's like 5 times the price of lm317's?

Is that normal or just my local electronics store raising prices ridiculously high?
Click to expand...

They are generally a better alternative to LM317's, an upgraded version if you like.

I'm not too sure about what the price should be though, I was very kindly donated one by a member.

It might be worth checking on digikey or sparkfun or something too see what they're prices are as a comparison
 
chipdouglas

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trevor is correct. you need to put load on the 5v. if you don't, you will still get voltage out on a meter. but when you go to actually use your psu it will shut off.

michael.
 
Asherz

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chipdouglas said:
trevor is correct. you need to put load on the 5v. if you don't, you will still get voltage out on a meter. but when you go to actually use your psu it will shut off.

michael.
Click to expand...

If he follows the wikihow link I posted he should be ok, they use a 10W 10ohm load resistor connected across the red and black wires.
 
LaZeRz

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Problem is, If I went to buy one of digikey I would have to pay 35 bucks shipping :/

Yeh, Im fine with making it and I've read thru everything

It actually seems pretty easy now after I've read over it a few times

I also might get a 330Ohm resistor and put it across the anode and cathode of a small LED so I have a status light

I also might get one of those little switches that have a dim orangey backlight and use that as a Switch

Thanks for the help! U guys rock!
 
Last edited:
Asherz

Asherz

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LaZeRz said:
Problem is, If I went to buy one of digikey I would have to pay 35 bucks shipping :/

Yeh, Im fine with making it and I've read thru everything

It actually seems pretty easy now after I've read over it a few times

I also might get a 330Ohm resistor and put it across the anode and cathode of a small LED so I have a status light

I also might get one of those little switches that have a dim orangey backlight and use that as a Switch

Thanks for the help! U guys rock!
Click to expand...

I did a quick online search for an Aus electronics site, came across this one:

LM350K +1.2-32V 3A Voltage Regulator - Jaycar Electronics

Whether or not it's any good I'm not sure, might be worth checking out some others though for postage quotes etc.
 
T

Things

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I've done exactly the same as what you're planning. Just stick a high wattage resistor on the 5V and that'll keep it happy with minimal load.

IMG_2018.JPG
 
LaZeRz

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Thanks!

Il have to visit Jaycar tomorrow after school

Btw Since the negative leads can supply far less current how can it be used to power something that takes bout 2.5 amps? Wont the protection circuit kick in?

Il get some binder posts, banana plugs, a Pot, a lm350/338, some breadboars, A project box, some caps and some resistors, Oh yeh, and some LED's and switches :D

I wish I could get those parts for cheaper.... this thing is going to cost me like 30-35 bucks from Jaycar....

Oh yeh any suggestions on a DMM?? Il probaly buy 1 from DX since its much cheaper :D
 
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T

Things

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You can't really use the negative power outputs for much, they're handy for testing circuits with opamps and stuff tho. I use them to power my laser power meter head sometimes.

As for Jaycar, if you go there enough, sometimes they'll give you a trade card for being a frequent customer. I got one for that reason :D
 
LaZeRz

LaZeRz

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wait a sec

If you only have a positive output how can you power something like a driver?

Sorry for my ignornce :p
 
T

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You have negative, ground and positive voltage, Laser drivers only need positive and ground.
 
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