Get an old toothbrush and some flux remover (isopropyl alcohol) and remove the excess flux on the solder side.

Thanks for the suggestion, but I didn't use any flux (I never use it). What you're probably seeing is remanants of solder resin.

 

Solder resin/rosen is indeed flux. The flux can be/usually is embedded into the solder, hence "Rosin core solder". Some is "water soluble", so you know what that means.

 

Per @MaxHeadRoom 's request, I've attached the .dwg file of this circuit in AutoCAD R14 format.

 

Very interesting project! you should look into doing a step by step instructable! ( www.instructables.com ), did you say this is only good for AC current measurement? could you briefly describe the operation of this circuits components?! it would be much appreciated, Thanks!

 

Very interesting project! you should look into doing a step by step instructable! ( www.instructables.com ), did you say this is only good for AC current measurement? could you briefly describe the operation of this circuits components?! it would be much appreciated, Thanks!

Thanks, but I don't think I'll be posting this at the instructable's website (call it AAC loyalty, if you will ). The circuit's description has already been given in post #1. If you have more specific questions in mind, then by all means ask away. And no, it doesn't only measure AC current, it can easily measure DC current too.

 

Thanks, but I don't think I'll be posting this at the instructable's website (call it AAC loyalty, if you will ). The circuit's description has already been given in post #1. If you have more specific questions in mind, then by all means ask away. And no, it doesn't only measure AC current, it can easily measure DC current too.

Fair enough, as for specific questions, so you have a 12VDC power supply, going through a voltage regulator to keep the voltage constant? and a voltage converter to range the voltage +-5v? some capacitors for filters? then the ferrite core with a built in hall effect sensor and a voltage sub-tractor op amp to make the offset -2.5v to +2.5v? then the output read off of a oscilloscope? would it be possible to have the output going to an arduino to an LCD to display the actual current measurement?.... sorry i don't know a whole lot, i have been given the thesis assignment to create a non-contact current measurement using a hall effect sensor... i am grateful i found your post as it gives me sort of a guide, thanks.

 

so you have a 12VDC power supply, going through a voltage regulator to keep the voltage constant?

That is correct. You could power up the thing with anything in the range of 7V to 40V, which is the working range of a 7805 regulator.

a voltage converter to range the voltage +-5v?

That's what the ICL7660 does, among other things, it converts a +5V source to a -5V one. Although it cannot deliver a lot of current, it's more than enough to be used as a reference for the OpAmp

some capacitors for filters?

C3, C4, C5, C6, C7 and C8 are decoupling capacitors. C1 and C2 are used as charge pump and charge reservoirs for the ICL7660 to generate its negative output.

then the ferrite core with a built in hall effect sensor

The sensor's datasheet is listed in post #2. It's the AMP 25 ammeter.pdf

a voltage sub-tractor op amp to make the offset -2.5v to +2.5v?

The sensor's output works in the range of between 0 to 5V, with it's null output set at 2.5V. That is, when no current is flowing through the sensor, its output is at 2.5V. That is why this circuit is needed, to subtract those 2.5V from the sensor's output so that 0V will be equal to 0 amps through the sensor. That makes it a lot easier and precise to read using an oscilloscope.

then the output read off of a oscilloscope?

Yes

would it be possible to have the output going to an arduino to an LCD to display the actual current measurement?

Yes it would, but you would need to use an analog to digital converter for that. I'm not sure if an arduino already has and ADC input in it. But if it does, I'd recommend that you do not use this circuit, since its output works in the range of -2.5V to +2.5V. It would be simpler to use the output from the Amploc sensor directly instead.

 

thank you kindly for the quick, detailed reply.. lastly i just want to ask if this amploc is an open loop or closed loop sensor? and what is the red led for? or the electrolytic/tantalum? thanks for the advice, the arduino does indeed have a built in ADC, so i guess most of this work could be done in the software coding opposed to the hardware?

 

FYI

I did not read the entire thread carefully, BUT you do need to be aware of ratiometic and absolute sensors.
Automobile sensors are mostly ratiometric. By, that, they are usually referenced to Vcc/2. This does not mean that if Vcc = 5V, it's referenced to 2.5V.

It means if Vcc = 5.000000 V its 5.000000/2 and if Vcc moves to 5.1 V it's 5.100000/2.

The A/D converters used in micros allow references to the 1/2 the supply voltage.

For fixed references, 2.50000 V sensors, the reference tolerance has to very good. e.g. So a DVM reads the right voltage.

It's a small point, but worth mentioning.

There are IC devices called "rail splitters". http://www.ti.com/product/TLE2426

 

i understand what your saying, where the VCC is +- it has to be bipolar it needs to be split, i have a 120VAC to 24VDC wall adapter, and im trying to use it with the LEM 55-P ( http://www.lem.com/docs/products/la_55-p_e.pdf ) current transducer with a source voltage of +-12V or +-15V, would i be able to a NMK2412SC ( https://www.digikey.ca/products/en?keywords=NMK2412SC ) this DC to DC converter to convert the 24VDC to +-12VDC for use with the sensor?

If yes, this converter has two seperate outputs, one +12V one -12V, would these outputs be tied together going into the VCC of the LEM sensor? Thanks.

 

i understand what your saying, where the VCC is +- it has to be bipolar it needs to be split, i have a 120VAC to 24VDC wall adapter, and im trying to use it with the LEM 55-P ( http://www.lem.com/docs/products/la_55-p_e.pdf ) current transducer with a source voltage of +-12V or +-15V, would i be able to a NMK2412SC ( https://www.digikey.ca/products/en?keywords=NMK2412SC ) this DC to DC converter to convert the 24VDC to +-12VDC for use with the sensor?

If yes, this converter has two seperate outputs, one +12V one -12V, would these outputs be tied together going into the VCC of the LEM sensor? Thanks.

According to the datasheets of both components you've mentioned, yes they would work just fine together.

But no, the DC-DC converter's outputs should not be tied together.
Instead, all you have to do is connect the converter's positive output to the sensor's positive input, the negative output to the negative input, and 0V output to the 0V pin of the transducer through a resistor and through a ammeter.
The type of transducer that you chose is not the same as the one in my original post. Your transducer is galvanically isolated and outputs a small current proportional to the current running through the wire being measured, while my sensor (also isolated) outputs a voltage.
What is it that you want to do? Measure instantaneous current through the wire, or measure the average current?

 

ok great, i see now that there are specific pins for positive and negative inputs, i was thinking of a different type of sensor where there was vcc, gnd, and Vout pins; anyway i plan on just measuring average current.. the 0v pin, is that considered ground? or is there no ground on the lem 55-p? my goal is to measure the current traveling through the current carrying conductor, so shouldnt ratiometric current be more suited than ratiometric voltage? i did take note of the differences when picking my sensor.

i was planning on having the output be read off of an arduino LCD, any insight? thanks.

 

ok great, i see now that there are specific pins for positive and negative inputs, i was thinking of a different type of sensor where there was vcc, gnd, and Vout pins; anyway i plan on just measuring average current.. the 0v pin, is that considered ground? or is there no ground on the lem 55-p? my goal is to measure the current traveling through the current carrying conductor, so shouldnt ratiometric current be more suited than ratiometric voltage? i did take note of the differences when picking my sensor.

i was planning on having the output be read off of an arduino LCD, any insight? thanks.

If you want to interface it directly to an arduino, then you have to use a sensor with an output voltage proportional to the current flowing through the wire. A good sensor for this purpose (considering a capacity of 100A) would be these found at the amploc website.
But these sensors will deliver an instantaneous signal in relation to the current flowing through them, i.e. they will output a 60Hz sinewave if standard 120VAC/220VAC mains is being measured.

To obtain the average (more formally, the RMS) of the current flowing through them, you must condition their outputs through proper circuitry. An excellent candidate for doing this (and I've actually used it before) is the AD536AJQ. Notice that the chip ain't cheap!

 

OK, i see; are there any ways to get current output interfaced to an arduino? the original sensor i was going to use was infact ratiometric voltage but it was of the open loop type and i had the lem55-p suggested to me, not looking to much further into it i ordered that part already, so voltage output would have been better for the arduino? then through software have that voltage converted into a current to display? damn. i wonder what the best way to display for the sensor i ordered.. hmm

i have oscilloscopes, multimeters etc. available for me to use but i thought the arduino and lcd added a nice touch

 

OK, i see; are there any ways to get current output interfaced to an arduino? the original sensor i was going to use was infact ratiometric voltage but it was of the open loop type and i had the lem55-p suggested to me, not looking to much further into it i ordered that part already, so voltage output would have been better for the arduino? then through software have that voltage converted into a current to display? damn. i wonder what the best way to display for the sensor i ordered.. hmm

i have oscilloscopes, multimeters etc. available for me to use but i thought the arduino and lcd added a nice touch

Arduino can do what you want, with the sensor that you've already bought, but it will require extra circuitry. First, for converting your sensor's output (which is in the form of current) to voltage of a certain range. Then that voltage would be interfaced to the AD536AJQ and from there to your Arduino.

But the way I see it, it's cheaper and easier to just buy one of the sensors I've suggested.