Higher current output from NI 6008

[johnsold]

That is basically the same way I have done it.

Tim,

If you want to adapt that for use with the USB-6008, connect the AO line to the Adjust terminal and eliminate the resistors R1 and R2.  You still need to provide a path for the minimum current through the LM317 (~5 mA - from memory without looking at a datsheet).  Do not try to sink that through the AO. Provide a resistor or current sink circuit.

Lynn

[Henrik_Volkers]

The proportional valves I have used in the past needed a power supply and a analog control voltage with about 10k input impedance.... shure you need 0..5V 500mA?

Anyway a very simple solution is one NPN (that can drive 500mA)  in a commom collector

The Vbe offset depends on temperature but if you run it in a control loop that doesn't care , BUT you can go down to 0V  , the 317 has 1.2..V min output and thermal protection...

[johnsold]

The LM317 output can go to zero if the adjust voltage goes negative.  The driver may need to sink current while at -1.25 V.

Lynn