High Current DC Power Supplies
2010 - 2011
I was cruising the internet a while back when I stumbled across a lot of used computer power supplies for 5.99 each. I had always wanted a high current DC power supply but I never wanted to spend 300 dollars for an industrial version. My buddy and I decided to buy 10 of these cheap power supplies and modify them to be DC power supplies for the average hobbyist. This is not a novel hack, as many people all over the web have done this, but no one seems to sell them. We sell them for 50$ a piece and we still have 5 left, so email me if you want one.
Below are some pics of the power supply. As you can see, they feature 5 and 12 volt outputs through banana connectors. The output voltage is not the steadiest I've ever seen, but it does put out a lot of current (see the graphs for the voltage-current dependency).
Power supply maximum capabilities:
+12V nominal @ 15 amps
+5V nominal @ 28 amps
Output voltage changes depending on current draw so please look at the graphs before deciding if this is the right power supply for you.
Possible application uses:
The main purpose of this power supply is to fill the demand for cheap, high current supplies. Possible uses include but are not limited to:
- High current applications
- Driving motors where a traditional 1-3 Amp power supply does not provide enough current
- Ham radio station setup
- Driving multiple banks of LED’s
- Creating an in-house 12V automotive “cigarette lighter” supply for car chargers
More technical background on this power supply:
Switching power supplies cannot work unless there is a minimum current draw. Internally, we have added a power resistor in parallel with the 5V line, guaranteeing this minimum current draw. This allows the power supply to maintain it’s operating voltage even when the user is not drawing any current through the banana connectors.
The indicator LED is connected to the “Power Good” line of the power supply. When illuminated, this LED indicates that output voltages have stabilized and are ready for use. Supplies have an internal fuse for safety, and have been tested to fail safe, meaning that if shorted, the voltage gracefully drops to zero until reset.
As with any power supply, the voltage will vary depending on how much current you draw. We have included two graphs to characterize these power supplies. The first graph shows both output voltages as a function of current draw from the 5 volt supply. No current was drawn from the 12 volt supply while producing this graph. As you can see, the 5 volt supply drops steadily as more current is drawn. The last data point shows that the 5 volt supply will output approximately 4.6 volts when the user is drawing 27 amps. The next graph shows both output voltages as a function of current drawn from the 12 volt supply. In this graph, no current is drawn from the 5 volt supply. Like the 5 volt supply, the output voltage on the 12 volt supply drops steadily as you draw more current. The last data point shows that when drawing 12 amps, the output voltage will drop to 11 volts.
Original Power Supply Specifications
Model: Foxlink FTPS-0302
Type: ATX
Maximum Output Power: 300W
Fan: Thermally controlled cooling fan
Over Voltage Protection: Yes
AC Input (50/60 Hz): 115V ~ 8A, 230V ~ 4A
Max DC Output: +5V@28A, +12V@15A
Dimensions: 5.5"(W) x 4.3"(H) X 5.9"(L)
+12V nominal @ 15 amps
+5V nominal @ 28 amps
Output voltage changes depending on current draw so please look at the graphs before deciding if this is the right power supply for you.
Possible application uses:
The main purpose of this power supply is to fill the demand for cheap, high current supplies. Possible uses include but are not limited to:
- High current applications
- Driving motors where a traditional 1-3 Amp power supply does not provide enough current
- Ham radio station setup
- Driving multiple banks of LED’s
- Creating an in-house 12V automotive “cigarette lighter” supply for car chargers
More technical background on this power supply:
Switching power supplies cannot work unless there is a minimum current draw. Internally, we have added a power resistor in parallel with the 5V line, guaranteeing this minimum current draw. This allows the power supply to maintain it’s operating voltage even when the user is not drawing any current through the banana connectors.
The indicator LED is connected to the “Power Good” line of the power supply. When illuminated, this LED indicates that output voltages have stabilized and are ready for use. Supplies have an internal fuse for safety, and have been tested to fail safe, meaning that if shorted, the voltage gracefully drops to zero until reset.
As with any power supply, the voltage will vary depending on how much current you draw. We have included two graphs to characterize these power supplies. The first graph shows both output voltages as a function of current draw from the 5 volt supply. No current was drawn from the 12 volt supply while producing this graph. As you can see, the 5 volt supply drops steadily as more current is drawn. The last data point shows that the 5 volt supply will output approximately 4.6 volts when the user is drawing 27 amps. The next graph shows both output voltages as a function of current drawn from the 12 volt supply. In this graph, no current is drawn from the 5 volt supply. Like the 5 volt supply, the output voltage on the 12 volt supply drops steadily as you draw more current. The last data point shows that when drawing 12 amps, the output voltage will drop to 11 volts.
Original Power Supply Specifications
Model: Foxlink FTPS-0302
Type: ATX
Maximum Output Power: 300W
Fan: Thermally controlled cooling fan
Over Voltage Protection: Yes
AC Input (50/60 Hz): 115V ~ 8A, 230V ~ 4A
Max DC Output: +5V@28A, +12V@15A
Dimensions: 5.5"(W) x 4.3"(H) X 5.9"(L)