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Author Topic: Build own variable PSU?  (Read 2581 times)

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Offline HDL_CinC_DragonTopic starter

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Build own variable PSU?
« on: September 22, 2007, 01:20:53 PM »
Would it be practical/economical enough to build your own variable Power Supply Unit? I want to build a PSU where I can control the voltage and amperage but I dont have a ton of money but I do have a lot of spare components/electronics at my disposal. Any suggestion as to what I should do?

Thanks guys


-EDIT-
would also be nice to be able to control the frequency too... :D
« Last Edit: September 22, 2007, 01:40:49 PM by HDL_CinC_Dragon »
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Offline h3ro

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Re: Build own variable PSU?
« Reply #1 on: September 22, 2007, 03:13:15 PM »
If you have a old power supply from a pc you would have a great start I think.

I think thous provide at least 12v and 5.

Offline Rebelgium

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Re: Build own variable PSU?
« Reply #2 on: September 22, 2007, 04:54:03 PM »
I'm quite experienced in this area,
I'm a member of a forum where there are lots of members have built these, and thus there are lots of tutorials... But unfortunatly it's all in dutch  :-[

Using a PC PSU is much, much easier. But there are downsides:
obviously there's no voltage regulating. You can only use 3.3  5  12  -3.3  -5  -12V.
and a more unknown disadvantage, but nonetheless very dangerous:
When you shortcut the supply (which happens much easier then you'd think) huge currents will immeadeatly flow, because a PC PSU CAN supply big currents, it will allow huge currents to flow when shortcutted. modern PSU's can supply 30A  @ 5V !!

When this happens on your breadboard for example, the connections aren't made for these currents, the connections will have enough resistance to make sure the PSU shortcut protection won't activate, causing your breadboard to heat, smoke and catch fire in a matter of seconds...

worst case scenario offcourse, but it is very possible
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Offline ed1380

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Re: Build own variable PSU?
« Reply #3 on: September 22, 2007, 08:11:49 PM »
also if you jumpstart a psu there has to be a load on it.
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Offline HDL_CinC_DragonTopic starter

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Re: Build own variable PSU?
« Reply #4 on: September 22, 2007, 09:28:35 PM »
Ive got an old 200w PC PSU here that interestingly enough has its own toggle switch instead of the usual thing where it waits for the motherboard to tell it the user presses the on button. I tried it out and it works... but as mentioned, theres no variance or flow control. I have several PC PSUs lying around... probably about 20.
Any English tutorials would be nice :P
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Offline snow

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Re: Build own variable PSU?
« Reply #5 on: September 23, 2007, 04:50:03 AM »
You might check out datasheet of L200. Has example of variable voltage regulator with current limiter.

 


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