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starship trooper

By starship trooper
in DIY Astronomer

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starship trooper

starship trooper

Posted
Posted

hi there,

I am playing about with making a power supply from a psu for all my scope needs and my usb hub needs a 7.5v at 2.5a supply and the only supplys i can get from a psu as you may know are 12v,5v,and 3.3v,.

So what i am wondering does anybody know how i would was a power regulator to get the 12v down to 7.5v and what elso i would need to do it?

Or do you think that i should just connect 12v upto and see if it opperates it?

Using another power supply is not an option because i am trying to keep it contained in one boxs to cut down all the leads around my scope.

All help is much appreciated thanks dazz:icon_salut:

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citaylor

citaylor

Posted
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Do you mean you are making a power supply from a PC PSU ?

If so this url is very helpful. To get the ~7.5v you can use the +12v as power, and +5v as ground to get the 7v - overclockers often do this in computers to slow fans down to make PC's quieter.

I hope this helps...

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starship trooper

starship trooper

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oh thats where i went wrong coz i tried that but i put the 12v and 5v together on a voltmeter and the psu stopped but now you write it i realizes the 5v is treated as an earth doh!;)

Here another one for you then my laptop needs a power supply of 19.5v at 4a would i be able to run that with the psu?

And you you think i should put any sort of fuse inline or is the protection that the psu has be ok?

Cheers dazz

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Gina

Gina

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Will the +5v supply take a negative current though? When running a computer the +5v supply is heavily loaded so the negative current from fans is swamped by the positive current to the computer logic - it just reduces the current slightly. You may need to add a load on the 5v supply. It just depends how the PSU is constructed. I don't know.

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Merlin66

Merlin66

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I run a 5A 12V PSU then add the 140W computer type transformer (maplin) 12V to 19V - I also use a similar set to 15V for the NEQ6.

The feed for the USB hub is similar a maplin 12V to 6V car transformer.

Being using this set-up for the last two years with no issues.

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Gina

Gina

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Switch mode PSUs are used for computers and other electronic equipment and it's the electronics of a mount where things will be most critical so I can see no reason for any problem.

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starship trooper

starship trooper

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well i tried the psu on my heq5 and the led was flashing when slewing,i tested the voltage and it was just below 12v so i gather that this isnt enough,it has enough amps at 18a.

How much volts can a heq5 mount take and how would i get me psu to meet requirment?

Cheers dazz

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