Constant Current Power Load
By: Steve Hageman
This power load is suitable for testing power supplies to 100V and 10
Amps. Power dissipation is limited to 50 Watts continuous and 150
Watts for short periods of time.
![](load_front.jpg)
The power load
chassis is constructed from a 6 inch tall heat sink extrusion. The
extrusion used had a slot cut in it that the front panel slips into.
The circuitry is built on this front panel. The top and bottom
panels, screw into the fins and hold the front panel in place. In the
back view the IRF150 pass transistor can be seen. The knob controls
the current that loads the power supply under test. One switch
controls the power, the other switch changes the meter from reading
the current to reading the voltage at the input terminals. The
battery on the side is used to power the FET driver. having this
battery on the outside of the load allows quick changing in case
someone leaves the load on over a long weekend, draining the
battery.
The load is useful in
a lab environment to quickly check the output of a power
supply.
The load works by
adjusting the voltage across a precision current sense resistor to be
the same as the reference voltage set by the knob. This provides a
constant current output that is not affected by the load
voltage.
Documentation
Available:
|Comments?| |To
Steve's Workshop Home|
Modified -
7Jan02