Hello,
has anyone done ammeter using arduino for measuring currents ~10 mA up to ~3 A
and voltmeter measuring voltages up to 15 V.
I would like to know what extra componets are needed for building this project?
I am thinking about using hall sensor for current measuring but don't have idea.
Those are all DC currents/voltages.
SimpleThings:
Hello,has anyone done ammeter using arduino for measuring currents ~10 mA up to ~3 A
and voltmeter measuring voltages up to 15 V.
I would like to know what extra componets are needed for building this project?
I am thinking about using hall sensor for current measuring but don't have idea.
Those are all DC currents/voltages.
I have done something similar and will soon be doing exactly this. The partlist depends on the accuracy you need and your budget.
thegoodhen:
I have done something similar and will soon be doing exactly this. The partlist depends on the accuracy you need and your budget.
Well I will be using it for debugging my DC motors
So +/- 5% is okay I guess and about the budget I will spend max around 30 bucks.
So could you tell me more about the project and the parts.
BillHo:
Digital multimeter shield for Arduino
http://duino4projects.com/digital-multimeter-shield-arduino/
This is already made multimeter if I am correct, but I want to make my own.
SimpleThings:
Well I will be using it for debugging my DC motors
Smart Car Robot Plastic Tire Wheel With DC 3-6v Gear Motor for Arduino for sale online | eBaySo +/- 5% is okay I guess and about the budget I will spend max around 30 bucks.
So could you tell me more about the project and the parts.
Alright. You'll need a programmable attenuator and/or amplifier.
This is pretty much all, really.
Actually, for reading the voltage, you don't even need that. Just use a simple resistive divider to get the voltage from 15 volts to 5. Something like 3x100k resistor would work well for this, I believe.
This gets you 1024 steps per the whole range, so 1024 steps for 15 volts. 1 step=0.0146 volts, yup, that's within your specs even with lowend resistors.
Why don't you just use a regular multimeter? logging capability, I guess?
Do you have a regular multimeter?
Is it acceptable to do the range switching manually?
thegoodhen:
Alright. You'll need a programmable attenuator and/or amplifier.This is pretty much all, really.
Actually, for reading the voltage, you don't even need that. Just use a simple resistive divider to get the voltage from 15 volts to 5. Something like 3x100k resistor would work well for this, I believe.
This gets you 1024 steps per the whole range, so 1024 steps for 15 volts. 1 step=0.0146 volts, yup, that's within your specs even with lowend resistors.
Why don't you just use a regular multimeter? logging capability, I guess?
Do you have a regular multimeter?
Is it acceptable to do the range switching manually?
I have regular multimeter ,I want to do this for a college project , also what attentuator and amplifier do you suggest.
I was thinking about resistive divider , but what if there will be voltage > 5V at analog pin to the GND , it could destroy the pin or even uC.
Range switching manually is acceptable.
This one looks adequate , what extra components are needed with hall current sensor?
travis_farmer:
after a brief read of the datasheet, the components are included on the sensor board. you can connect +5Vdc to the 5V hole, ground to the GND hole, and the Arduino analog pin connects to the Vo pin. keep in mind that this sensor has a gain control, so check the output with a multimeter to assure it is less than, or equal to 5Vdc.~Travis
What about measuring voltages with voltage divider that are above 5V, since arduino pins can take max 5V , what do you suggest maybe some OP amp would do the trick?
Have read the link I posted?
You can use the Zener diode to clamp the Vmeas potential ( the voltage applied to the analog input A0 of the “Arduino”) at 5.6V and to protect the Atmel chip.
BillHo:
Have read the link I posted?
You can use the Zener diode to clamp the Vmeas potential ( the voltage applied to the analog input A0 of the “Arduino”) at 5.6V and to protect the Atmel chip.
Yeah, Zener diodes are great solution for this, so basically I would need a Zener diode with 5.6 V break down voltage?
SimpleThings:
I have regular multimeter ,I want to do this for a college project , also what attentuator and amplifier do you suggest.
I was thinking about resistive divider , but what if there will be voltage > 5V at analog pin to the GND , it could destroy the pin or even uC.
Range switching manually is acceptable.
Don't worry about it too much. There are protective diodes to keep this from happening. It's gonna be alright with 100k resistors. In fact, even Atmel says this is okay...
They say it here
And I'd suggest using a simple opamp for reading the current. LM358 will be okay. Just switch in different feedback resistors to change gain. Don't forget to measure the offset voltage and correct for it in software!
With LM358 I wouldn't need any current sensor?
I would prefer not buying current sensors if I think twice because it's basically already built current sensor basically and I am doing this for educational purposes.
For this schematics LM358 would also be fine ?
post image online
SimpleThings:
For this schematics LM358 would also be fine ?
post image online
Yea, this seems ok to me. Just make R3 switchable for the different ranges and you're done. The configuration is a noninverting amplifier. The formula is:
A=1+(R3/R2)
where A is the amplification coefficient.
Using that figure the values for R3 for different gains. Be careful about the rail-to-railness of the opamp (have a sufficient overhead, it won't give you 5V out with 5V rail...) and compensate the input offset, which also gets multiplied by your gain.
Edit: also don't make the gain crazy high, about 100 is max I'd go.
thegoodhen:
Yea, this seems ok to me. Just make R3 switchable for the different ranges and you're done. The configuration is a noninverting amplifier. The formula is:A=1+(R3/R2)
where A is the amplification coefficient.
Using that figure the values for R3 for different gains. Be careful about the rail-to-railness of the opamp (have a sufficient overhead, it won't give you 5V out with 5V rail...) and compensate the input offset, which also gets multiplied by your gain.
Edit: also don't make the gain crazy high, about 100 is max I'd go.
Would adding potentiometer as R3 work ?
Well I have some theoretical knowledge about the op amps ( amplification , inner resistance , etc.) , but could you be more specific on rail-to-railness I don't know much about it.
SimpleThings:
BillHo:
Digital multimeter shield for Arduino
http://duino4projects.com/digital-multimeter-shield-arduino/
This is already made multimeter if I am correct, but I want to make my own.
No, the link from BillHo is to a project to make a DMM shield from parts, not an already made multimeter.
And it looks like it may be a good one.
Nice info,
Urgent,
I really need the metering for kwh meter. 1 phase and 3 phase.
Do you have the program?
Please send me the diagram lay out and program.
The voltage is 230 V and the ampere can reach 50-80 A, frequency 50 Hz
You can choose the sensor using CT, Relay or what ever the cheapest one
Please email to m.eng.leonardo@gmail.com
+62 811166 861
I will really appreiciate your help
ChrisTenone:
This is already made multimeter if I am correct, but I want to make my own.No, the link from BillHo is to a project to make a DMM shield from parts, not an already made multimeter.
And it looks like it may be a good one.
Yes I read the project I wasn't referring to BillHo but to someone posting current sensor link.
Project looks pretty decent.
I've ordered parts as said in the project for ammeter and voltmeter:
3x BSS123 PMOS
1x PTC 500mA
3x LM358
1x 5.6 V Zener diode
I have to ask:
The author also made ohmmeter , could you tell me if inverter for this purpose could be made of any general purpose BJT like BC547 and also why input and output pins of inverter are feed back to the switches?