Hi I have a circuit for a gradiometer that I am interested in making. I have had a lot of experience on analog circuits so it would present me with any problems. Where I completely fall down is on digital. I have attached a circuit diagram of the item, which uses 2 fluxgate sensors and an SCL007 chi. The chip should is to allow connection to an LCD display and a data logger, but where to begin. What would I need to purchase and how would I connect it? Then of course there is the question of writing the control software.

If anybody can offer any help or guidance I would greatly appreciate it.


You're gonna need to find the datasheet for the device - which shows how to talk to the chip. Without that, you can't proceed with the digital part.

A quick googling did not find me such a datasheet, just the app notes that you pulled that diagram from.

What does a gradiometer measure?


Hi I am told that the SCL007 is a programmed PIC 16C54A - 20/P


Hi I can only assume nobody can help on this one. Will have to look elsewhere

Hi, a gradiometer measures the earths magnetic field, strength and direction.

rw you have not told us what flux sensor you have, so how can we help you.
We need to know its output signal and power supply requirements.

Your original post did none of that and you didn't answer vffgaston's question.

We can only help you if you provide us with info AND answer our questions.

Tom....... :slight_smile:

Hi the sensors are FGM3’s from Speake & Co. as is the SCL007.
Data sheets for this is attached.


That is just a product brief. There is not enough information in it to fully implement your project, but it would be simple to measure the output of the sensor using an Arduino -- you just need to measure the period of the output pulse.

Nick Gammon describes how to do that accurately here: Gammon Forum : Electronics : Microprocessors : Timers and counters