I bought a NI cRIO chassis including a NI 9263 module. The 9263 module was meant to control a pneumatic valve accepting a 0-10V control signal.
At the time of purchase, I was convinced that all 0-10V control modules and valves should work together and power requirements were some industrie standard... Unfortunately, looking at both datasheets it turns out not to be the case. The NI 9263 can output max. 1mA/ch, while the valves need at least 1.6mA to function.
Buying a higher-rated NI module is very expensive just to get the required current, so it was suggested I build an amplifier to place between DAQ and valve.
I'm no electrical engineer, so my knowledge is just basic. I was hoping someone more knowledgeable could tell me wether my idea will work, or will fail.
My idea was to use an operational amplifier with enough output power to control the valves. Since I want to amplify all 4 output channels of the 9263, I was looking at packages which include 4 op-amps in one chip. I would connect the opamps in a voltage follower configuration, so there is no amplification and output current comes from the opamp supply rather than the NI 9263.
My idea was to use a Tracopower TMT 15215 power supply to convert AC voltage to +/- 15V DC, as a power supply (15 Watt) for the op-amp. I would use a National Semiconductor LM837 as the op-amp chip.
As far as I am capable of checking this system, I found that it should be able to source/sink almost 40mA per op-amp. Using +/- 15V supply leaves sufficient headroom between my 0-10V and rail to work over the entire range I want. Controlling valves is something that's not super-fast anyway, so I think it's dynamic characteristics (rise-time) are also more than sufficient. (I even believe it to be over-dimensioned, but with little knowledge, I prefer to be on the safe side).
Can anyone confirm this will work? Or let me know what problems I might expect, or what I could possibly do better?
