Power sensor signal conditioing

[ericgibbs]

Oh I missed the capacitor part .

This means that I need to have a capacitor between the sensor and my pin 1?.

The transformer is just wrapped around one side of the magent, I do not have any specs for it but as in my first post i was able to get some readings regarding the ohms, I do not know if this helps.

Its the details of the current sensor that causing me a little concern.

To protect the AD736 it maybe necessary to include some form of voltage clamp on the wire thats going to the capacitor pin 1.

Is the current sensor home made.?

 

[charbel89]

The sensor is one that you can buy from the market.

Basically i bought it from Amazon for £9.99.

It is normally interfaced with a wireless sender that uses 433MHZ to transmit to a base station.

**broken link removed**

Its the details of the current sensor that causing me a little concern.

To protect the AD736 it maybe necessary to include some form of voltage clamp on the wire thats going to the capacitor pin 1.

Is the current sensor home made.?

 

[charbel89]

So the capacitor I am looking at this one:

**broken link removed**

Code: JA75S

Which is a 10uF as specified in the AD736 datasheet page 17.

 

[ericgibbs]

So the capacitor I am looking at this one:

**broken link removed**

Code: JA75S

Which is a 10uF as specified in the AD736 datasheet page 17.

The 0.1uF is the input cap, see RED ring, the 10uF are decoupling caps, see RED rectangle.

The BLUE wires are the input you require.

 

[charbel89]

Right thanks for that.

This means that i am only missing the single capacitor unless I need to connect ground to pin4 in which case I will need another 0.1µf

The 0.1uF is the input cap, see RED ring, the 10uF are decoupling caps, see RED rectangle.

The BLUE wires are the input you require.

 

[ericgibbs]

Right thanks for that.

This means that i am only missing the single capacitor unless I need to connect ground to pin4 in which case I will need another 0.1µf

Pin 4 MUST go to a negative supply, about -3.4V
also its decoupled to 0V via a 0.1uF.

 

[charbel89]

Eric,

I am really sorry about this, you must think I am an idiot or something.

What does the decoupling to 0v exactly means?

Pin 4 MUST go to a negative supply, about -3.4V
also its decoupled to 0V via a 0.1uF.

 

[ericgibbs]

Eric,

I am really sorry about this, you must think I am an idiot or something.

What does the decoupling to 0v exactly means?

Its common practice to connect power supply lines to 0V via a low value capacitor. They reduce any electrical noise on the supply lines so that the ic dosn't malfunction. They also help reduce any noise the AD may make, that could cause problems elsewhere in the circuit.

Look at the LIGHT BLUE rectangles, these are decoupling.

NOTE: the caps 10uF in the RED rect are also power decoupling.

When you are testing it may be necessary to add some more conditioning to the signal, read up on the function of CF2 shown in the image.

 

[charbel89]

How about buying this pcb:

**broken link removed**

What will it take to make this work with my sensor?


Also thought this might be of interest:

This is the edemoboard of the sunspot schematics

 

[ericgibbs]

How about buying this pcb:

**broken link removed**

What will it take to make this work with my sensor?


Also thought this might be of interest:

This is the edemoboard of the sunspot schematics

hi,
I cannot access the datasheet for the AD736 pcb DigiKey part.
The price is high £71GBP and they are showing zero stock.?

I would think for what you have in mind it would be an overkill, unless you have a number of AD736 systems to develop.

Just buy an AD736 and a plug in project board. Remember you need a low current dual power supply for the AD736, adjustable from about +/-3V they +/-12Vdc

 

[charbel89]

Yeah the price is a bit on the high side, and yes it is an overkill I will not be needing this for any other sensor, at least for the time being.

So let me list what I need to buy:
1 - AD736 IC.
2 - Bread Board. (Off couse wire connectors will be nice to have - ebay )
3 - 2 X 0.1µf capacitors.

The sunspot edemoboard produces +3V and +5V and has a ground so I will assume I can use that, else I will have to get 2 AA battery holder.

I guess thats about it.

hi,
I cannot access the datasheet for the AD736 pcb DigiKey part.
The price is high £71GBP and they are showing zero stock.?

I would think for what you have in mind it would be an overkill, unless you have a number of AD736 systems to develop.

Just buy an AD736 and a plug in project board. Remember you need a low current dual power supply for the AD736, adjustable from about +/-3V they +/-12Vdc

 

[ericgibbs]

Yeah the price is a bit on the high side, and yes it is an overkill I will not be needing this for any other sensor, at least for the time being.

So let me list what I need to buy:
1 - AD736 IC.
2 - Bread Board. (Off couse wire connectors will be nice to have - ebay )
3 - 2 X 0.1µf capacitors.

The sunspot edemoboard produces +3V and +5V and has a ground so I will assume I can use that, else I will have to get 2 AA battery holder.

I guess thats about it.

Lets know how it goes, others may follow the same route.

 

[charbel89]

Lets know how it goes, others may follow the same route.

Will do . I am sure the sunspot guys will be keen on adding this to their blog

One more thing does it matter what type of capacitor I get? Looking at maplin site they have many different 0.1µf makes and models.

And many thanks for all you efforts, I have almost given up all hope of getting this thing to work.

 

[gg339]

Hi all,

I've read with interest the thread above - I'm trying to do exactly the same thing without any success.
I have a CT with 3200 Turns, and have presently loaded it with a 100R resistor. This signal I'm now trying to get into a PIC adc, by way of an ADE as previous, but readings are way off.

Can I ask did the previous questioner get sorted with the ADE and CT, and if so is there any information/ complete schematic available.
I notice a contributor posted that the ADE must get a -3.5V supply, however the app notes suggest you can use a single rail?
In addition, does one connect the CT wires to pin1 and pin2?

Thanks in advance for any additional pointers.

Regards,
GG339

 

[charbel89]

I am still waiting for my kit to arrive.

It will be a week or two before I get some results.

Hi all,

I've read with interest the thread above - I'm trying to do exactly the same thing without any success.
I have a CT with 3200 Turns, and have presently loaded it with a 100R resistor. This signal I'm now trying to get into a PIC adc, by way of an ADE as previous, but readings are way off.

Can I ask did the previous questioner get sorted with the ADE and CT, and if so is there any information/ complete schematic available.
I notice a contributor posted that the ADE must get a -3.5V supply, however the app notes suggest you can use a single rail?
In addition, does one connect the CT wires to pin1 and pin2?

Thanks in advance for any additional pointers.

Regards,
GG339

 

[charbel89]

I am still waiting for my kit to arrive.

It will be a week or two before I get some results.

Just a quick update:

I got the kit and connected as in the diagram but I do not seem to be getting anywhere.

Any advice on what I am missing is very much appreciated.

I now have the Mastech MS3302:
**broken link removed**

Thanks.

 

[charbel89]

Another question: How do I measure the output? at the moment I am connecting my multimeter to the output and to the -v supply to the chip.

Is this correct?

With regards to the image posted:

Pin 1 & 2 are connecting to my Ac current transducer.
Pin 4 to my battery negative & Pin 7 to positive battery (2 AA @ 1.5V each).
Pin 6 is my expected output which i am measuring as stated above.

Now for the blue and red line do I need those connected too?

I am trying to get 0-3V output that represents my transducer current readings.

If I need the blue and red line what should the capacitor size be at CF2 and with regards to the 33µF on the red line what does the 16V+ mean.

Any helpful feedback on this are much appreciated.


Thanks a lot.

Just a quick update:

I got the kit and connected as in the diagram but I do not seem to be getting anywhere.

Any advice on what I am missing is very much appreciated.

I now have the Mastech MS3302:
**broken link removed**

Thanks.

 

[ericgibbs]

hi,

I have looked thru the meter spec.

Are you getting the 'ac' output voltages you expect from the clamp ammeter.?

 

[charbel89]

hi,

Hi Eric,

I have looked thru the meter spec.

Are you getting the 'ac' output voltages you expect from the clamp ammeter.?

Thats a good question:
My multimeter shows nothing on DC mv and if I switch over to AC I do not see anything either but I Assumed it was becuase it is not sensitive enough to pick AC at such low voltage.

I tried the Ohms and I can see a change when I put load on the live wire, so I assumed a signal must be comming through.

If you have any suggestions I will be heading off to Maplins in the next couple of hours..

Thanks a lot.

 

[ericgibbs]

Thats a good question:
My multimeter shows nothing on DC mv and if I switch over to AC I do not see anything either but I Assumed it was becuase it is not sensitive enough to pick AC at such low voltage.

I tried the Ohms and I can see a change when I put load on the live wire, so I assumed a signal must be comming through.

If you have any suggestions I will be heading off to Maplins in the next couple of hours..

Thanks a lot.

Whats the lowest range on your ac DMM.?

EDIT: the most sensitive range is the 1mV/0.1Aac.

Does your clamp require that you clamp only one of the conductor pair.?

A 2KW electric fire or electric kettle would be a good load test.
The 2KW fire should give about 80mVac output.