DIY Gauss Meter

[Bertoa]

For my energy projects I needed a meter to measure the magnetic field, induction or flux density. The price of a good Gauss meter in the shop was about 120 dollar. Some study in the field showed me the simple design of such a meter. Anyone can make this was my thought. On internet I found some bad designed circuits. My meter is simple, cheap (10$), sensitive and reliable. The few components are build on a small piece of PCB. Only four main components are there: the voltage regulator (LM7805), a Ratiometric Linear Hall Effect Sensor (SS498A from Honeywell), a mini digital voltmeter and a window comperator (LM339). The hall sensor probe can be used 'free' from the box. There is only one setpoint for the offset between the North (red LED) and the South (green Led) Pole.
The only thing to do is to make a table with the conversion numbers between voltage (2.5V is the zero point) and the Gauss and Tesla units.
I am really surpriced of the performance of this instrument. By measuring my computer monitor (Imac) I found 22 places with a strong magnetic field. Maybe it's time for an iron frame around the screen.

https://www.youtube.com/watch?v=mRWQT8NCzk8

[Matthew Jones]

Thats really cool. Have you been able to compare it to lab quality gauss meter or anything similar to compare accuracy? I can't seen to find the hall sensor but I find others like it. I was just wondering about the size of it.

Good work thanks for sharing.

Matt

[blackchisel97]

http://wiki.icub.org/images/e/ec/Datasheet_hall.pdf

Using Ratiometric Hall Effect Sensors

V

[Bertoa]

Thanks Matt for appreciating the project. No, I could not compare this meter with a lab one. I hope to update this thread later with my expieriences and additions. For now I can compare the field of permanent and electro magnets. The hall sensor I use is a mini version of the SS495 series. I think that you can get more brands with the same (or better) performance. I am really surpriced how sensitive this one is. The voltmeter shows normally 2.5V (the zero point)
With a higher density of the North pole the volt meter goes from 2.5V to 0V and for the South pole from 2.5V to 5V. For calculating to the Gauss unit you take a factor 1.3 times 1 milivolt. 1V is 1300 Gauss.