Hello everyone,
I need to check if there is AC current going through a cable and send that information to the Arduino.
I know there are Current Sensors, that send Analog Data about the current going through. They measure the current intensity and send the according voltage.
However, i dont need that, i only need to detect current or not.
Is it posible to find a cheaper, smaller, electronic solution? instead of using a fully current sensor?
Thanks very much!!
Chelo.
Make your own? Wrap some wire loops around the current carrying wire. When current flows it will induce a current in your windings (so you're essentially making a transformer), feed that current to a resistor, a voltage will be create that you can read with analog input (or feed into the input of a comparator (see the LM358 circuit that does Arduino voltage source switching) and get a high/low output that way.
Anything you create to detect the current becomes a "sensor" so it fails your criteria by it's very existence.
I think you are asking for a Yes/No indication.
You need to decide/determine what is the minimum current that will show as Yes or On. Then you'll have an analog sensor connected to a comparator with hysteresis. Then you'll have your digital On or Off signal.
Reed switch may works, you need appropriate coil:
http://www.engineersgarage.com/articles/reed-switch-specifications
A single inductor and an opamp would do the job as well
Until the OP gives us more information, we can't really help.
Why not use this ?
Well, that is the current transformer part. Probably a couple of diodes and use the internal comparator in the Arduino, and you are done.
Keep in mind that only one of the AC wires can pass through there. If you simply place it around the AC cord with both wires, you'll get nothing.
I need to detect if a lamp is turned on. Some low consume lights only use 60mA on 220v.
How can I detect 60mA current?
I bought the 5A current sensor, and the sensibility was too low, I couldn't detect it...
Please Help!
Can you explain why you need to measure current? 60 mA may be troublesome to measure reliably at mains voltages.
If you want to sense if a light is on you can do that in several ways it depends on what you want to achieve
CrossRoads:
Make your own? Wrap some wire loops around the current carrying wire. When current flows it will induce a current in your windings (so you're essentially making a transformer)
No, that's not a transformer, its two circuits with no mutual inductance between them.
For a transformer both wires must wrap together, in parallel. So you could just run the
sense wire alongside the sensed wire for a few feet. Wrapping a wire around another
is the wrong geometry.
I suspect the original poster wants to detect the presence or absence of mains voltage,
not current, anyway (ie is the wiring live?).
For this simple proximity will work (wrapping the wire around would do this), but a
fairly high-impedance sensor is needed - luckily the Arduino pins are high impedance
so you'd almost certainly get a rough trapezoidal voltage (clipped by the Arduino's
protection diodes) into either a digital or analog pin.
Stray electric fields would be an issue, as would keeping the sense wire short, since
capacitive sensors pick up any signal in range indiscriminantly. Some experimentation
would be required...
[ And make sure the mains wiring is in good nick, no damage to the insulation ]
60 mA is a very small current to measure. You would need a 100mA CT
That's an Instrument Class CT.
100 mA CT
A photodiode next to the lamp seems the way to go.
if you loop the wire through the sensor, you get a multiple for every loop. 4 loops and you have almost 2.5 amps if your load is 600ma, if your load is 5 amps, you would get 20 amps
If you want:
1 A binary sense of is it on or is it off ...... go with a photodiode as KenF suggests
2 An analog range of the degree of light (lux) ..... use a photoresistor using the Map function on the Arduino to scal the range and trigger point
3
Apologies, my last transmission went too early. Finger trouble.
If you want;
1 to know if the light is on or off, binary response, use a photodiode as KenF suggests
2 to respond to various levels of light, analog response, use a photoresistor as part of a potential divider pair and scale this on an analog pin using the Map function to scale the level of sensing
3 a slower response, then measure the heat from the lamp (if it is producing a measurable amount) with a thermistor.
Peter
Apologies, my last transmission went too early. Finger trouble.
If you want;
1 to know if the light is on or off, binary response, use a photodiode as KenF suggests
2 to respond to various levels of light, analog response, use a photoresistor as part of a potential divider pair and scale this on an analog pin using the Map function to scale the level of sensing
3 a slower response, then measure the heat from the lamp (if it is producing a measurable amount) with a thermistor.
Peter
I will use a photodiode I guess, however what if it is day time? does it still work?
Are there any auto feed leds?
That means, that it would feed automatically from the current, without connecting, im saying from the magnetic field produced by the flowing electric current.
Thanks!