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New power hub using desktop PC PSU?

Stargazer33

By Stargazer33
in DIY Astronomer

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Stargazer33

Stargazer33

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Just looking into this again and I came across this: http://www.ebay.co.uk/itm/Silent-Alpine-700W-PC-Computer-Power-Supply-Unit-With-120mm-Fan-2-x-Sata-/252654310619?_trksid=p2141725.m3641.l6368

Does it look any good? Seems to have more than enough amperage and with +3.3V, +5V & +12V outputs I can step up/down to any voltage I need.

The built in EMI filter sounds good too. As long as this thing is genuine, coming from eBay!

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Dr_Ju_ju

Dr_Ju_ju

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PC power supplies tend to have much better smoothing\cleaning of the output voltages, than some of the cheaper switched mode supplies (do you hear any hum\noise components from the audio outputs of a pc ? and any radio receiver placed near a PC isn't interfered with...)  whereas the PSU's I use for the 3D printers are exceedingly RF noisy, so I've added low pass filters to the outputs to try & clean things up.

I run my mount PC\Mount\Cameras\USB Hubs\Focusers\Dew heaters etc. all from a single 700W power supply, which is mounted in a weather proof case bolted to the pier base, with no issues regarding interference to any other devices.

 

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pete_l

pete_l

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On 11/5/2016 at 10:52, iapa said:

@SkyBound as are most of the mains - 12V 5A adapters we buy?

Agreed a bench PSU is the way to go - as long as it's metering is accurate :)

Is it still possible to buy bench PSUs with transformers?

Although, so far as noise goes not being a switched PSU doesn't automatically make them better. You can get considerable noise off a linear regulator if it isn't  used properly. And they can be a lot more fragile if abused.

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iapa

iapa

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4 hours ago, Dr_Ju_ju said:

There's this:

http://www.maplin.co.uk/p/maplin-97w-dc-fixed-voltage-bench-power-supply-xm21x

or this, for more current

http://www.maplin.co.uk/p/375w-linear-dc-variable-voltage-bench-power-supply-rp10l

 

 

These days I'm not so keen on using something with variable outputs - since I stopped building them myself, and have more expensive toys now - and would be concerned about knocking the output controls too high.

If it was documented by manufacturers that 15V input was not going to damage anything - I'd be in there :)

But they all say 12V....

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RayD

RayD

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34 minutes ago, iapa said:

These days I'm not so keen on using something with variable outputs - since I stopped building them myself, and have more expensive toys now - and would be concerned about knocking the output controls too high.

If it was documented by manufacturers that 15V input was not going to damage anything - I'd be in there :)

But they all say 12V....

I wouldn't worry too much.  In general this is a "nominal" supply requirement and they actually have a range in which they will work.  See below from my AZ EQ6 manual:

 

Output Voltage: DC 11V (minimum) to DC 16V (maximum). Voltage not in this range might cause permanent damage to the motor controller or the hand controller.

• Output Current: 4A for power supply with 11V output voltage, 2.5A for power supply with 16V output voltage.
• Do not use an un-regulated AC-to-DC adapter. When choosing an AC adapter, it is recommended to use a switching power supply with 15V output voltage and at least 3A output current.
• If the power voltage is too low, the motor controller will stop the motors automatically.

I find my AZ EQ6 is really happy at 13.8V, and if you look SW actually suggests a preferred 15V as this of course in turn drops the current and all the associated heat issues, and pushes it above the point that low voltage problems are likely to occur.

I would suggest that if a piece of equipment has a critical requirement of 12V exactly, then it would have an internal regulator in any case.

I have a couple of bench supplies, including the Nevada one from FLO, which is fixed at 13.8V, and is a great little unit for the money.

FLO Nevada Power Supply 

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iapa

iapa

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5 hours ago, RayD said:

I wouldn't worry too much.  In general this is a "nominal" supply requirement and they actually have a range in which they will work.  See below from my AZ EQ6 manual:

 

Output Voltage: DC 11V (minimum) to DC 16V (maximum). Voltage not in this range might cause permanent damage to the motor controller or the hand controller.

• Output Current: 4A for power supply with 11V output voltage, 2.5A for power supply with 16V output voltage.
• Do not use an un-regulated AC-to-DC adapter. When choosing an AC adapter, it is recommended to use a switching power supply with 15V output voltage and at least 3A output current.
• If the power voltage is too low, the motor controller will stop the motors automatically.

I find my AZ EQ6 is really happy at 13.8V, and if you look SW actually suggests a preferred 15V as this of course in turn drops the current and all the associated heat issues, and pushes it above the point that low voltage problems are likely to occur.

I would suggest that if a piece of equipment has a critical requirement of 12V exactly, then it would have an internal regulator in any case.

I have a couple of bench supplies, including the Nevada one from FLO, which is fixed at 13.8V, and is a great little unit for the money.

FLO Nevada Power Supply 

Thanks - just need to keep digging for that data for my  mounts and ancillary kit.

 

 

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RayD

RayD

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8 hours ago, Gina said:

I run all my kit from 13.8v :)

That's what I meant by 12V being nominal.  I would't think any kit is going to blow up running at 13.8, although Atik do note this as the top end of their range.  All mine runs on 13.8 also and I've never had an issue, and in fact as noted with the mount, it can actually be beneficial.

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Dr_Ju_ju

Dr_Ju_ju

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I have yet to see any equipment that does not have an on-board regulator, even Cameras & Arduinos have them.

So as long as you don't go too far over the 'reccomended nominal' voltage, the worst you would be doing is increasing the voltage drop accross that regulator, which usually means more heat needs to be dissapated. 

It is also required for some single chip regulators (7812, 7815 etc.) that the source voltage be at least 3 volts above the output voltage, to ensure correct operation.

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