Power sensor signal conditioing

[Nigel Goodwin]

Thanks Nigel,

I will look into this. I am placing an order from RS-components so I will check their range.

RS do a decent range of Veroboard, I usually get mine from there.

 

[charbel89]

RS do a decent range of Veroboard, I usually get mine from there.

Any recommended one? I am browsing through them now.

 

[Nigel Goodwin]

I usually get a big sheet, 434-201 lasts a good long time.

They list two smaller sheets as well, but avoid the fourth choice, which has 0.15 pitch instead of 0.1 pitch.

 

[charbel89]

Yeah I noticed the 0.15 one.

I just placed an order for that one.

VeroPins???

I usually get a big sheet, 434-201 lasts a good long time.

They list two smaller sheets as well, but avoid the fourth choice, which has 0.15 pitch instead of 0.1 pitch.

 

[Nigel Goodwin]

Yeah I noticed the 0.15 one.

I just placed an order for that one.

VeroPins???

I use them, usually the single ended ones - I would suggest you get a track cutting tool as well - for years (decades) I used a twist drill in my fingers, and it's SO MUCH EASIER to use the proper tool

 

[charbel89]

I setup the CA3140 as described in the diagram.

My output is at 2.86VDC.

VR1 is 1.08 VDC.

I used for VR1 a 20k pot.

The pot from 1 to I did not change the settings on it. It is in the dial is in the pointing to the centre.

+5 VDC is fed directly and the ground is fed to a 10µf capacitor and then to the +5 VDC as shown in C1.


Do I call this a success? or I am still missing something?

Thanks.

hi,
Looked at the pics.

Remember you are working with millivolt level ac signals.

You must keep the interconnecting wires as short as 'reasonable' else you will pick up mains em radiation which will give reading errors.

I would recommend that you build the CA3140 amplifier, this will increase the voltage that is output from the AD736.
You can use your dc meter to check the output.

Use a pot about 10k or 20K as a test input source for the amplifier.

I'll attach a sketch.

 

[ericgibbs]

I setup the CA3140 as described in the diagram.

My output is at 2.86VDC.

VR1 is 1.08 VDC.

I used for VR1 a 20k pot.

The pot from 1 to I did not change the settings on it. It is in the dial is in the pointing to the centre.

+5 VDC is fed directly and the ground is fed to a 10µf capacitor and then to the +5 VDC as shown in C1.


Do I call this a success? or I am still missing something?

Thanks.

hi,
If I am reading your post correctly, you are saying you havn't adjusted the 20K pot.???

You need to turn the pot to give a 'X' point voltage of 1Volt [use a small screwdriver]
Once you have set 'X' at 1V then adjust the gain pot to give +3V on the output of the CA3140 'Y'.

Read the instruction notes on the drawing.
The term 'SET' means adjust.

Do you follow.?

 

[charbel89]

Morning Eric,

The VR1 pot has been adjusted to give 1.08VDC I could try and fine tune it further to give 1 VDC exactly.

The gain pot becuase it is shorted if I tun it to one side it will go below 2.86 VDC and if I turn it to the other and once it passes the centre point it never goes beyond 2.86 VDC.

The only pot I have not adjusted is the one connecting 1 to 5.


I assumed those figures are sort of correct with a certain margin of error or I am wrong?

thanks.

h
If I am reading your post correctly, you are saying you havn't adjusted the 20K pot.???

You need to turn the pot to give a 'X' point voltage of 1Volt [use a small screwdriver]
Once you have set 'X' at 1V then adjust the gain pot to give +3V on the output of the CA3140 'Y'.

Read the instruction notes on the drawing.
The term 'SET' means adjust.

Do you follow.?

 

[ericgibbs]

Morning Eric,

The VR1 pot has been adjusted to give 1.08VDC I could try and fine tune it further to give 1 VDC exactly.

The gain pot becuase it is shorted if I tun it to one side it will go below 2.86 VDC and if I turn it to the other and once it passes the centre point it never goes beyond 2.86 VDC.

The only pot I have not adjusted is the one connecting 1 to 5.

I assumed those figures are sort of correct with a certain margin of error or I am wrong?

thanks.

hi,
The 1.08V on VR1 is OK for the present.

The VR2 pot is not shorted.
You should be able to set the VR2 gain pot from 1 thru times 4
So the output pin should read from about 1V thru 4V as you adjust VR2.

It sounds as though you have got a wiring error.

Post a picture on how you have it wired.

 

[charbel89]

Will do.

Just give me 20-30 minutes.

hi,
The 1.08V on VR1 is OK for the present.

The VR2 pot is not shorted.
You should be able to set the VR2 gain pot from 1 thru times 4
So the output pin should read from about 1V thru 4V as you adjust VR2.

It sounds as though you have got a wiring error.

Post a picture on how you have it wired.

 

[charbel89]

Here are the pics.

If anything is not clear or would like a different view please let me know.

Thanks.

Will do.

Just give me 20-30 minutes.

 

[ericgibbs]

hi,
I think I need some time to digest these pics.!

Its like an aerial view of an Amazonion rain forest, I must go and sharpen my machete.

I'll be back.!

 

[charbel89]

Sorry ,
I was attempting to do it myself just for the fun of it, and I can imagine how difficult it is.


Maybe I will try a small video.

hi,
I think I need some time to digest these pics.!

Its like an aerial view of an Amazonion rain forest, I must go and sharpen my machete.

I'll be back.!

 

[charbel89]

here are a couple:

https://www.youtube.com/v/SEhv_mWVCd4

https://www.youtube.com/v/WQoVpQaHeCo

Sorry ,
I was attempting to do it myself just for the fun of it, and I can imagine how difficult it is.


Maybe I will try a small video.

 

[ericgibbs]

hi,
Looked thru the images, its almost impossible to make any sense of the layout.

Whats this group of resistors for.? Ref this image.

Re layout the circuit using short pieces of wire. Old single strand phone cable is OK.

Where possible keep the layout something like the circuit diagram layout.

 

[charbel89]

Those resistors are in series totaling 22k. the connection between +v and VR1.

I will also try to use phone cables, to make it more understandable.

hi,
Looked thru the images, its almost impossible to make any sense of the layout.

Whats this group of resistors for.? Ref this image.

Re layout the circuit using short pieces of wire. Old single strand phone cable is OK.

Where possible keep the layout something like the circuit diagram layout.

 

[charbel89]

Here the updated pictures.

Wow what a difference.

I also was able to set the VR1 (20k pot) to produce 1.01 VDC.

The VR2 is producing 2.86-2.90VDC

Those resistors are in series totaling 22k. the connection between +v and VR1.

I will also try to use phone cables, to make it more understandable.

 

[ericgibbs]

Here the updated pictures.

Wow what a difference.

I also was able to set the VR1 (20k pot) to produce 1.01 VDC.

The VR2 is producing 2.86-2.90VDC

As you say Wow.!

I can now see the project board, give me a few minutes, I'll go thru them.

 

[ericgibbs]

hi,
That looks OK to me.

For a test remove the 10K pot between pin 1 and 5 [ leave the wire links in place], leave it out for now.

I assume the the +V is 5Volts.

Try adjusting VR1 and measure the X and Y voltages, just do about 5 readings from say X = 0, 0.2, 0.5, 1.0, 1.5V
As close as you can get, its difficult with a single turn pot, lets know the Y voltages.

 

[charbel89]

pin1 to pin5 pot removed.

With VR2 turned all the way to the linked pins.

X = 0 Y=0
X = 0.2 Y=1.14
X = 0.5 Y=2.69
X = 1 Y=2.86
X = 1.5 Y=2.86

+V is 4.96 volts

Thanks

hi,
That looks OK to me.

For a test remove the 10K pot between pin 1 and 5 [ leave the wire links in place], leave it out for now.

I assume the the +V is 5Volts.

Try adjusting VR1 and measure the X and Y voltages, just do about 5 readings from say X = 0, 0.2, 0.5, 1.0, 1.5V
As close as you can get, its difficult with a single turn pot, lets know the Y voltages.