¿QUESTION? PC Power Supply?

Looking for a base for a DC to DC converter. The Cheapo at 22 dollars and 350 watts still looks unbeatable at this point. The DC to DC unit is current limited and 10 amperes at 5 volts is not worth considering.

Thanks folks.

Matt_Colie wrote:
Yes, an ATX power supply is good for about 3 amps. Some may be more, but they have to be turned on remotely (simple) and the +5 needs load or the system will shut down.

Just Google ATX power supplies and you will find it.

Matt

No. Not true at all.

You would have to be talking an extremely old 100W AT style power supply in order to only get 3A at +12V rail..

Not to mention only the real old ORIGINAL IBM PC (5150 model from 1981-87) Which looks like THIS had a minimum load requirement for the +5V rail (it came equipped with a load resistor which had to be removed if you upgraded to a hard drive.

That same load resistor continued to be needed for the next in line IBM "XT" and the need for the load resistor was abolished forever when IBM introduced the IBM "AT" which was the first run of 286 processors..

Modern day ATX power supplies DO NOT "NEED" a load resistor in order to operate. However the power supply only MONITORS the +5V rail for VOLTAGE REGULATION.. You can operate a ATX power supply with nothing attached to the +5V rail but the other voltages may sag more under load since they are not being monitored for sag.

Modern day high wattage ATX power supplies can pack quite a punch in current on the +12V rail.. A typical 300W ATX power supply will have a rating of about 15A on the +12V rail..

A 450W ATX supply can have 20A-25A on the +12V rail.. and you can get ATX supplies of 850W and even 1000W sizes!

If you are looking for a battery charging supply then you should look elsewhere.. this is not for you.. the +12V rail is designed to deliver 11.9V-12.1V.. Not anywhere near what you would need for charging a 12V battery.

MEXICOWANDERER wrote:
Thanks for realizing I have truly lousy internet here with TelCel using the cellular. Looks like I have to abandon The Great Plan.

Oh well the Cheapos will work.

It's difficult finding a 120vac / 36-vdc converter that is very inexpensive. For LED lighting.

If you don't need isolation from the line voltage, I think you could in theory wire up a 48V transformer as an autotransformer (connecting the primary and secondary in series with the proper polarity) that should be relatively close to 36V rms nominal output. Add a bridge rectifier and a filter capacitor for a super simple unregulated linear power supply, and a little fiddling with the loading and maybe some current limiting or voltage dropping should get you something that's adequate. You would need to derate the output current of the 48V transformer...by about 30% if I'm doing my math properly (since the secondary winding now carries both the input and output current).

There are several different PC power supplies.. Some laptop supplies are indeed in the 12-16 volt range.

But most Desktop/Tower supplies are multi-voltage including both positive and negative with respect to ground voltages, one of which is 12. Two of which are five, and there may be others.

Thanks for realizing I have truly lousy internet here with TelCel using the cellular. Looks like I have to abandon The Great Plan.

Oh well the Cheapos will work.

It's difficult finding a 120vac / 36-vdc converter that is very inexpensive. For LED lighting.

Yes, an ATX power supply is good for about 3 amps. Some may be more, but they have to be turned on remotely (simple) and the +5 needs load or the system will shut down.

Just Google ATX power supplies and you will find it.

Matt

They have 12v
But it is typically Quite small
The 5v side is heavier with more amps than the 12v lines
In a PC, the 5v is doing all the heavy lifting, powering the cpu and graphics etc
The 12v handled fans etc...

Multiple voltages at different currents
+12Vdc
-12Vdc
+5Vdc
+3.3Vdc
-5Vdc
etc...

A Google search of an ATX supply will get you more than you want to know
Remember they are typically software controller - to enable them a simple short between a few oins gets the beast alive

A specific model search might help
Antec Model PP-303XP

Typical desktop PC ATX switching power supplies output +12, -12, +5, and +3.3 volts, all referenced to ground. You might find the Tom's Hardware site useful for additional information.

I just looked that up on Amazon. Apparently they are, but, if your question has to do with battery charging, it seems unlikely they're robust enough to pump out a lot of amps for any length of time.