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126 posts

Master Geek
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Topic # 193829 25-Mar-2016 17:49
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A while ago I started making a bench top psu out of an atx power supply. I kind of lost interest due to not being able to find a suitable enclosure. I Started making one out of plywood (think it is 5 ply), a little hard to get it to line up perfectly with my wood work skills, 5 ply looks too thick and clunky, also it was scrap wood and not completely straight. 

 

My question is does anyone know of a suitable way to achieve an enclosure. The way I would like it is to have the atx psu sit in the bottom, and have a compartment of similar size as an atx psu sit above it. So kind of like a double, vertical stacked, atx enclosure. I intend to put switches/lights/volt display on the front. 

 

Rough size 12cm wide x 25 cm high x 15 cm deep. Cheaper the better. 

 

Any one got any ideas of something similar/suitable or a way I can make something easy. 


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458 posts

Ultimate Geek
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  Reply # 1519772 25-Mar-2016 18:18

Here are a couple of photos of the one I made in a plastic box.

 

Click to see full size

 

Click to see full size




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Master Geek
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  Reply # 1519776 25-Mar-2016 18:28
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k1w1k1d:

 

Here are a couple of photos of the one I made in a plastic box.

 

Click to see full size

 

Click to see full size

 

 

Awesome, I like the variable voltage but I think it will be above capability to implement for version 1.

 

I just found this one made of plywood:

 

http://www.dothediy.com/2015/09/variable-benchtop-atx-power-supply.html

 

looks awesome, maybe I just need to work on my wood working skills.


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Ultimate Geek
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  Reply # 1519788 25-Mar-2016 19:16

The variable voltage is easy to do with one of these. I just unsoldered the blue 10k pot from the circuit board and ran wires to a 10-turn 10k pot on the front of the box.

 

http://www.ebay.com/itm/2PCS-150W-DC-DC-Boost-Converter-10-32V-12-35V-6A-Step-Up-Power-supply-Module-/400442480064?hash=item5d3c3b55c0


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  Reply # 1520318 27-Mar-2016 11:30
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What voltage range can you get with those?


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  Reply # 1520336 27-Mar-2016 12:43

Specs say 35v, but I never take it over about 29v, as voltmeter is only rated to 30v max.

 

Don't need any higher voltage than that for 24v automotive gear.

 

 


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  Reply # 1520343 27-Mar-2016 13:23
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k1w1k1d:

 

Specs say 35v, but I never take it over about 29v, as voltmeter is only rated to 30v max.

 

Don't need any higher voltage than that for 24v automotive gear.

 

 

If its like the one I got, it has a jumper that can be cut and then another pad to feed 5-30v into to power the display and the input can go to about 50ish before it hits the limit of the ADC.





Richard rich.ms

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  Reply # 1520465 27-Mar-2016 17:07
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mb82:

 

 

 

looks awesome, maybe I just need to work on my wood working skills.

 

 

 

 

You might find your local timber yard  or joinery shop will cut ply/MDF to your sizes on their table saw.

 

Usually it's easy enough to do good drilling / gluing etc yourself , but i find it hard to cut a very straight line with home tools.

 

My local place does it for not much more than the materials cost. 


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  Reply # 1520466 27-Mar-2016 17:14
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I find the easiest way to get exact sized boards when my tablesaw is a piece of crap is to clamp or screw a board to what I want to cut and then use a template bit in the router, the fence on my table saw is useless, apparantly because it is a "contractor" grade one not a cabinet maker grade one.





Richard rich.ms

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  Reply # 1520765 28-Mar-2016 15:21
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Saw this, thought of this thread.

 





Richard rich.ms



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Master Geek
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  Reply # 1522671 30-Mar-2016 10:12
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k1w1k1d:

The variable voltage is easy to do with one of these. I just unsoldered the blue 10k pot from the circuit board and ran wires to a 10-turn 10k pot on the front of the box.


http://www.ebay.com/itm/2PCS-150W-DC-DC-Boost-Converter-10-32V-12-35V-6A-Step-Up-Power-supply-Module-/400442480064?hash=item5d3c3b55c0


How do I calculate the current draw on the 12v rail to get 24v @ 5 amps on the output of the dc converter.

Also the pot you are referring to is that on the dc converter itself?

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Master Geek
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  Reply # 1523024 30-Mar-2016 22:58
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What about 3-6mm acrylic? I've got a laser cutter that would make a box that big, and cut out any holes for meters and switches.

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  Reply # 1523057 31-Mar-2016 05:36
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mb82:
k1w1k1d:

 

The variable voltage is easy to do with one of these. I just unsoldered the blue 10k pot from the circuit board and ran wires to a 10-turn 10k pot on the front of the box.

 

 

 

http://www.ebay.com/itm/2PCS-150W-DC-DC-Boost-Converter-10-32V-12-35V-6A-Step-Up-Power-supply-Module-/400442480064?hash=item5d3c3b55c0

 


How do I calculate the current draw on the 12v rail to get 24v @ 5 amps on the output of the dc converter.

Also the pot you are referring to is that on the dc converter itself?

 

V=IxR or I=V/R or R=V/I


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  Reply # 1523351 31-Mar-2016 14:30
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Will prob be around 12A after allowing for power supply losses. Also note that some ATX power supplies don't like high loads on the 12V outputs. When there is no load on the 5V and 3.3V outputs. This is because the cheap supplies use a single stepdown transformer with different output tappings for the different voltages. Increasing the current draw on the 12V rail causes the output voltage's on the 5V and 3.3V rails to increase. (Unless you also increase the current draw on those rails as well). Eventually the supply shuts down as the over voltage protection activates.

 

To avoid this you need the type that is built as a really high current 12V supply. And which has inbuilt "buck" converters that run off the 12V rail to produce the 5V and 3.3v rails. Seasonic X series are one of the better type.






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  Reply # 1523364 31-Mar-2016 14:42
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you can throw a large power resistor over the smaller power rails to make it has some power draw to make the PS think its working :)


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  Reply # 1523368 31-Mar-2016 14:49
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People say that but I've not had a problem with 20+ amps on the 12v line and nothing on the 5 or 3.3v.

Just don't buy a multi rail 12v one since you want all the power to one thing, not several like in a PC.




Richard rich.ms

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