Hi, im trying to model a transconductance circuit (or VCCS)
to power a pneumatic proportional valve, using an Arduino DUE
with an opamp and a resistor. The valve specs are 24Vdc and
current from 0 to 85mA, need to be current controlled. It's
simply a resisance of about 200ohm. The signal comes from Arduino
DAC into the amplifier.
So, the arduino signal goes into the noninverting input of the
opamp (i'm using an LM7171, dont know if it's the optimal one),
a precise resistor of 27.4ohm is inserted from the inverting
input to ground and the valve from opamp output to inverting
input. The opamp is single supplied from 30V (V+) to ground (V-).
When arduino applies 2.7V to opamp input, the output should
supply 100mA.
Ive tried simulating this circuit with some programs and seems
working well. But I'm not really good in electronics and i don't
wanna burn the opamp or arduino for a stupid mistake.
Is this circuit a good choice? Is this opamp a good choice too?
Should I add a resistor from arduino output to opamp noninverting
input to prevent high current flowing from or to arduino input (it
can bear like 20mA, i know ideally there should not be any current).
Is it a problem that the load is not grounded?
Should i add some capacitor somewhere in the circuit (I'm not sure
what I'm asking here but I've seen a lot of circuit with capacitors
for stability).
Some more information: this circuit controls a pneumatic valve, so
it's a mechanical system. I chose a fast opamp even if i won't give
an input signal with a freuency higher than 500Hz. I chose it basically
because it can give me 100mA and be supplied with 30V.
Thanks in advance for any answer
to power a pneumatic proportional valve, using an Arduino DUE
with an opamp and a resistor. The valve specs are 24Vdc and
current from 0 to 85mA, need to be current controlled. It's
simply a resisance of about 200ohm. The signal comes from Arduino
DAC into the amplifier.
So, the arduino signal goes into the noninverting input of the
opamp (i'm using an LM7171, dont know if it's the optimal one),
a precise resistor of 27.4ohm is inserted from the inverting
input to ground and the valve from opamp output to inverting
input. The opamp is single supplied from 30V (V+) to ground (V-).
When arduino applies 2.7V to opamp input, the output should
supply 100mA.
Ive tried simulating this circuit with some programs and seems
working well. But I'm not really good in electronics and i don't
wanna burn the opamp or arduino for a stupid mistake.
Is this circuit a good choice? Is this opamp a good choice too?
Should I add a resistor from arduino output to opamp noninverting
input to prevent high current flowing from or to arduino input (it
can bear like 20mA, i know ideally there should not be any current).
Is it a problem that the load is not grounded?
Should i add some capacitor somewhere in the circuit (I'm not sure
what I'm asking here but I've seen a lot of circuit with capacitors
for stability).
Some more information: this circuit controls a pneumatic valve, so
it's a mechanical system. I chose a fast opamp even if i won't give
an input signal with a freuency higher than 500Hz. I chose it basically
because it can give me 100mA and be supplied with 30V.
Thanks in advance for any answer