# Arduino V3 with transducer

Hello, first of all please excuse my bad english, not my native language.

I have an arduino v3 board and a transducer that i need to connect my board to it. so far so good but the problems start here, my transducer works at 18-36V DC and 50mA, it responds in 4-20mA.

I am attaching a snip of the transducer specs…

Can i connect it to a diffrent power source and then to my board?

Is there a driver for the board that allows this much current?

And this is the most unhoped solution, but can you suggest a board that can help? Arduino is a great language.

The Arduino analog inputs can measure voltages from 0 to 5V. By connecting a resistor to your current source you can convert current to voltage.

20 mA = 5V through 250 ohms

It’s not clear what they mean by “Max Load <500 Ohms” in the specifications. Does that mean that 250 Ohms is OK because it is less than 500?

I honestly have no idea, those are the specs translated from my native language, so i'm guessing it am not supposed to put more than 500 ohms in it.

So can i use an external power source for the transducer, then put a resistance on the analog input on the arduino to get the power down to 4.8 volts? Can you help me with a schematic?

I am planning to use a 19 volts generator.

So can i use an external power source for the transducer,

Yes.

then put a resistance on the analog input on the arduino to get the power down to 4.8 volts?

Connect a 250 Ohm resistor from the Arduino analog input pin to Ground. Connect the 4-20 mA current loop sensor across the resistor. A full-range reading (1023) will be 20 mA. The minimum reading should be about 205. If you get a zero reading it means the wire to your sensor is broken (which is why they use 4 mA as the minimum).

Connect a 250 Ohm resistor from the Arduino analog input pin to Ground. Connect the 4-20 mA current loop sensor across the resistor. A full-range reading (1023) will be 20 mA. The minimum reading should be about 205. If you get a zero reading it means the wire to your sensor is broken (which is why they use 4 mA as the minimum).

Golden oldies. 4-20 ma loop signals from yesteryear.

Your answer is sound but there is one catch. Which side is assumed to be active? The gadget may supply the current or expect the reader (Arduino) to supply it. In any case he should follow your instructions. “Max load” suggests that it is an active device and can drive 20 ma into a 500 ohm resistance. Lower ohms should certainly be OK.

By the way how would you generate a 4-20 ma signal from an Arduino?

I don’t really understand what you are saying, i am attaching a picture of the transducers connector cables, can you help me with a schematic?

I don't really understand what you are saying, i am attaching a picture of the transducers connector cables, can you help me with a schematic?

With the transducer powered up, simply connect a 220 ohm (or similar) resistor across pins 2 & 3. No Arduino at this point. Vary the transducer across its range and check the voltage at the resistor. You should get 0.88 volts to 4.4 volts if the device is outputting 4-20 ma.

What does this transducer do? Your diagram says is "digital output" which is rather vague.

It's a vibration transducer