Signal amplification

Hi there.

I wanna integrate a process control system with Arduino, but it uses I/O voltages of 0-9V. If possible to amplify an output signal on Arduino Uno? How can I do it with NO using an operational amplifier, or s necessary to ue it?

Simple way is to use transistor to buffer each output. Example, NPN transistor such as 2N2222A. Arduino output connects to base thru 330 ohm resistor, emitter to Gnd, collector to your device with 1K resistor to 9V. This will invert the signal, easy to address in Arduino software. Arduino High = Low at the collector, and vice versa.

Can also find many logic chips that will do this in a nice 14 or 16 or 20 pin package with 8 inputs, 8 outputs, power and Gnd, maybe an output enable.

Use a simple NPN inverter to convert 5V signals to 9V, and use a voltage-divider to drop 9V signals to 5V.

https://www.google.com/search?site=&tbm=isch&source=hp&biw=1151&bih=823&q=npn+inverter https://www.google.com/search?site=&tbm=isch&source=hp&biw=1151&bih=823&q=voltage+divider

EDIT: Following Bob, if you have a lot of control signals, then you can use an ULN2803 which has 8 inverters in the chip.

https://www.google.com/search?q=uln2803&rlz=1C1RNLG_enUS517US518&oq=uln2803

ULN2803 comes to mind as one part. Will need output pullup resistors.

Hex inverter like 74F06 will give you a better Low level signal. http://www.digikey.com/product-detail/en/N74F06D,623/568-1710-1-ND/763508

Do you mean a digital 0 to 9V signal, or an analog signal that may be anywhere between 0 and 9V?

If digital (either 0 or 9V, nothing else), then use the advice above.

If an analog voltage, then you'll need to use something like analogWrite, which is really a PWM signal, smooth it, then use an Op Amp to scale it from 0-5V to 0-9V.

I drew up a schematic in LTSpice for an earlier question about using the Arduino to drive 0-10V:

https://www.dropbox.com/sh/rj0vzz93dfnakq8/AAAswoj6NOtnh92GOWen2zmQa?dl=0

Or you could use analogWrite, leave it as PWM, drive an NPN transistor as above with a Vcc of 9V, then smooth that signal to an analog voltage. A big problem with this is that an assymetrical drive will give you a nonlinear result. So you'd really need to do something like use an NPN as a level shifter to 10V logic, then a CMOS inverter as a buffer to drive an RC smoothing circuit.

I wanna integrate a process control system with Arduino, but it uses I/O voltages of 0-9V. If possible to amplify an output signal on Arduino Uno? How can I do it with NO using an operational amplifier, or s necessary to ue it?

If I am not mistaken you are referring to an Analog In (0 - 10V) or and Analog Out (0 - 10V) or both.
Almost all process control equipment offers this options (VFDs for example). I have never seen one
that used 0 - 9V. This is an unusual voltage range but certainly possible. In order to have two way
communication you can use a voltage divider to get the output down to (0 - 5V) to use with an arduino
analog Input but to get communicate from the arduino to the Process Control, you need a DAC (like
the Adafruit MCP4725) and a single supply op amp to amplify the DAC output to 0 - 9V range. The
Linear LT1215 is a good choice. You can power it with a 9V wall wart. You need a gain of 1.8, which is
a Non-Inverting amplifier with a feedback resistor/input resistor ration of 0.8 because the formula for
that configuration is

Vout = Rf/Rin + 1.

raschemmel's advice is good, a DAC will give you a much cleaner result.