convert 0-10Vdc to -10 to +10Vdc 2

[grobbins]

I am trying to run a hydraulic proportional valve with plus/minus 10 volts (0 is neutral) from a hall-effect joystick that produces 0 to 10 volts.

Do you know how to convert this and if so, can you adjust the min and max outputs? (I need to set min and max hydraulic flow settings when the joystick is in max position)(ramp settings would be nice if there is that option)(the valve amplifier does not have any controls on it)

Thanks.

 

[BrianG]

Yes, this can be done with relatively simple analog op-amp circuitry to level-shift, scale, ramp, etc., BUT a few more details will be needed.

1) What kind of circuit load the hydraulic valve will impose, i.e. you have stated plus/minus 10V but what is the load resistance / maximum current loading? (unless the valve has its own voltage-controlled drive circuits then driving the valve coils directly may require a small power amplifier output stage.)

2) What power supplies are available to operate the "converter" circuitry?

3) Does the joystick have a mechanical, e.g. spring-return, centre position when you let go? (may require a "hold" circuit if you don't want the valve to go to the neutral position as well)

 

[edsparks]

If board level circuits aren't what you're looking for, an off the shelf signal conditioner would do this nicely. We use Action Instruments' Ultra Slim Pack Isolators to perform similar functions. They can be ordered in a variety of input/output configurations. The one you would want is their model G408-1001. It is small, about 3-4" square, 3/8" thick, din rail mountable, adjustable zero and span,... A very good product. I think they cost around $250-300 USD. Check their web site:

http://www.actionio.com

Good Luck,
EDSPARKS

 

[grobbins]

Thanks for the help. The requirement has been reduced. I am only using a 0-10 Vdc from the joystick and the valve range is 0-10 Vdc. I still need a way to change the min and max settings going to the valve. The joystick will always produce 0-10, but I would like to use trim pots to set the min and max to the valve (ex. 1-7.2 Vdc).


BrianG:
1)the valve has a amplifier that powers the solenoids. The amp is controlled by the 0-10Vdc signal. The amp is powered by a 24Vdc power supply. We are using a very low current Voltage signal to control the amp.
2)24Vdc
3)the joystick will spring center to neutral and the voltage output would then be 0.

edsparks:
thanks for the site. those items look nice, but now that I do not need to convert the signal (eliminated plus minus 10Vdc), do you know of a less expensive device?

Thanks again.