Higher current output from NI 6008

[Sparkman2]

I want to use the analog output of a 6008 to control a proportional solenoid valve that draws approximately 400mA and requires a 0 to 5 VDC signal. I thought I had seen such a circuit before on the NI site, but I can not locate it. How can I accomplish this control scheme?

Thanks,

Tim

[apok]

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@Sparkman2 wrote:

I want to use the analog output of a 6008 to control a proportional solenoid valve that draws approximately 400mA and requires a 0 to 5 VDC signal. I thought I had seen such a circuit before on the NI site, but I can not locate it. How can I accomplish this control scheme?

Thanks,

Tim

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optocoupler,scr, transistor,fet, driver/ relay combo....

[Sparkman2]

Thanks.  A driver/relay combo isn't much help on an analog circuit though.

Does anyone perhaps know where I can find a schematic of something that has been tested and actually works? It has been too many years since I dealt with the design side.

[AnalogKid2DigitalMan]

Also the ubiquitous ULN2xxx series (2003) in this case, it even includes the protection diode:

http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATASHEET/CD00001244.pdf

-AK2DM

[AnalogKid2DigitalMan]

The 6008 DAQ has digital outputs too.

-AK2DM

[Sparkman2]

I have used the ULN2803 in numerous digital control systems but it doesn't have an analog output.

Thanks,

Tim

[apok]

0 through 5V......use the AO of the daq to control a variable power supply or serial/usb/gpib out to it...

[AnalogKid2DigitalMan]

Ah, missed the proportional portion of the post.

Don't they typically use PWM to modulate the coil current/voltage, I have never used them in practice.

Or maybe an anlaog output driving a MOSFET?

-AK2DM

[johnsold]

An adjustable voltage regulator such as the LM317 could work. You need to add a protection diode.  The AO voltage would be set to 1.25 V higher than the desired solenoid coil voltage and would be connected to the adjust terminal.  The power supply to the regulator needs to be greater than 8 V.

I have used these regulators as speed controls for small motors. They work well for moderate performance systems such as this will be.

Lynn

[AnalogKid2DigitalMan]

'Mr." Lynn:

Didn't think of that approach for the proportional solenoid.

Scary you mentioned the 317 for motor control, yes they do work quite well! Here is the one I designed for a couple applications.

-AK2DM