I am trying to build a +5V regulator using a LM350K. I am using a 28V5A transformer and a two diode (GI750) full wave rectifier. I get about 10.4V No Load voltage at the filter cap (10,000uf) I am using 120 Ohm resistor for R1 and a 180 Ohm resistor plus a 500 Ohm Pot. for R2. Those are the only components used in the regulator.
I have noticed that the regulator handles variations on the input side of it well. However, the output voltage varies significantly according to the resistance of the load. If I adjust the regulator to provide ~5.25V at no load, the voltage will then drop to 4.66 when the load is a 1.4 Ohm resistor that results in 3.4 amps of output current.
The voltage drop apparently is inversely proportional in a virtually linear fashion to the output current. Here are links to a jpg's of the ciruit and performance:
Does anybody know how to stablize the output voltage with regard to output current?
BTW I thought this device might be malfunctioning so I substutited a LM150K and got the same results. So, I concluded this is just the way the devices functions in this circuit.
Additionally, the heat sink I am using is rated at 5.5 degrees per watt. So the thermal resistance of the whole assembly is about 8 degrees per watt.