Need a 12v Power Supply for your scope?

I needed a 12v power supply for my Dob, so that I could operate it from a 115v A/C wall plug. Well, there are power supplies out there that cost a bit that at regulated, but I thought I would like to save money and do it myself.
So, I took an old computer power supply and removed most of the wiring and wired in a 12v cigarette lighter plug. It provides 12v regulated power of up to 5 amps.
Cost, $0 for old power supply and $1.50 for a cigarette lighter socket. So $1.50 for a great power supply that is even fan cooled!

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Floyd Blue said:
Cost, $0 for old power supply and $1.50 for a cigarette lighter socket. So $1.50 for a great power supply that is even fan cooled!

Floyd,

Ingenious! So is this next accessory for Blue Sky?

Paul

Hi Floyd,

Nice way to keep some of this stuff out of the dump !

Could the 12V adapter plug be put outside the PS case ?

As you may know, the doubler circuits inside these cheap switching PS's can can generate some pretty nasty voltages that are not isolated from the power line, and have minimal internal clearances to squeek by the UL/ TUV standards. Once they go though the switcher / transformer and filters, then the 12V is safe. So I would vote for putting the adapter outside the case to avoid any of the internal nasty stuff.

I would also recommend putting the cheap power supply into another more robust box, like a sturdy plastic toolbox with some kind of added cut-out ventilation, as the high voltage in the cheap PS is likely right next to the ventilation slots in the metal box.

This would also let you store an extension cord, and have multiple 12V adapter plugs attached to the tool box sides.

Hi Floyd,
I did this a while back with copier/fax 15volt power supplies for two of my Super Polaris mounts. I thought the Vixen power supply for $150 was nuts!
I bought a number of the units from a surplus supplier.They were modified to output a 11.98 volts (12v). They were switching regulators, they do not regulate well without a load. If nothing is plugged in you would get a voltage about 1 to 2V lower than normal rating with a voltmeter. The output would stabilize under light loading.(ex. a small 12v light bulb or a telescope controller) Since unloaded the voltage output drops below nominal, there is no appreciable danger plugging and unplugging the units while powered.
They work fine with the MT-1 motors on my Polaris and the they're small.

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