Magnetic Field Probe

[BostonBrooks]

Hi all,

I am working on building the magnetic field probe from ITMD3. There is a discrepancy between the parts list on page 547 and the schematic on page 543. Details in attached CSV files. Could someone please correct this discrepancy for me?

Kind regards,
Boston

[Carl-NC]

It appears that the parts list is mostly correct with the exception of maybe R17 & R18. I had to look at my circuit board to see what I actually built and for R18 I used 12k but for R17 I used two parallel resistors of 180k||160k. This gives 84.7k so the ratio is then 84.7/12 = 7.06 and the resulting voltage is right at 10V. If you use R17=100k and R18=15k then the result is 9.5V which is probably close enough, or 110k/16k gives 9.76V and 130k/18k gives 10.2V. These all assume E24 (5%) resistor values, if you use E96 (1%) values then you can get closer.

Here are the corrected schematics and parts list:




I also see that the layout includes the option of using a 6-pin chip for IC4. This allows the use of a synchronous switcher which eliminates D2. I used this on my board but I don't know what I put in for IC4, but it uses R14=120k and R15=2k as listed in the book.

Thanks for catching this, it will be corrected in 3.05.

[BostonBrooks]

Great work thanks Carl

[Carl-NC]

The parts list still had an error, R15 should have been 11k, not 2k. The post above has been corrected.

[Carl-NC]

I also see that the layout includes the option of using a 6-pin chip for IC4. This allows the use of a synchronous switcher which eliminates D2. I used this on my board but I don't know what I put in for IC4, but it uses R14=120k and R15=2k as listed in the book.

The chip I used was a Nisshinbo R1207N823B.

[pito]

what is doing IC2a ?

[Carl-NC]

Automatic offset correction, otherwise at really high gains the LT6231 will saturate.

[pustareka]

3D hyper sensitive spherical vector B-field detector. 3 sensors were needed - one for every axis XYZ.

[Eddy71]

The diagram doesn't show the power and ground pins for the LT6231, LM393 and TL072. There are multiple power supplies and two grounds in the diagram. Can you tell me which circuits are correct to use?

[Carl-NC]

VCC = +10V
VEE = ground =

[JoyJo]

It appears that the parts list is mostly correct with the exception of maybe R17 & R18. I had to look at my circuit board to see what I actually built and for R18 I used 12k but for R17 I used two parallel resistors of 180k||160k. This gives 84.7k so the ratio is then 84.7/12 = 7.06 and the resulting voltage is right at 10V. If you use R17=100k and R18=15k then the result is 9.5V which is probably close enough, or 110k/16k gives 9.76V and 130k/18k gives 10.2V. These all assume E24 (5%) resistor values, if you use E96 (1%) values then you can get closer.

Here are the corrected schematics and parts list:




I also see that the layout includes the option of using a 6-pin chip for IC4. This allows the use of a synchronous switcher which eliminates D2. I used this on my board but I don't know what I put in for IC4, but it uses R14=120k and R15=2k as listed in the book.

Thanks for catching this, it will be corrected in 3.05.

And how is the sensor made? Is any ready-made element used or completely homemade?

And why the knot assembled on lm393? Is this an indicator that all voltages are available?

[profesor]

Can P.I. detectors measure the field of view of these detectors?

[Carl-NC]

And how is the sensor made? Is any ready-made element used or completely homemade?

And why the knot assembled on lm393? Is this an indicator that all voltages are available?

See the parts list in post #1. The LM393 is just a good/bad battery indicator, leave it out if you prefer.

[Carl-NC]

Can P.I. detectors measure the field of view of these detectors?

No

[Eddy71]

Quasi - PI (from the book)