magnetometer ?

[g6ejg]

Hi,

I want to make add a "magnetometer" to my 1-wire setup - ie a device to measure the earths geomagnetic field. This is useful for predicting aurora and, as a radio ham, for radio propogation predictions.

There is a basic design here:-

http://www.dcs.lancs.ac.uk/iono/aurorawatc...rs/compass.html


this basically drives a voltmeter.

So what I want to do is replace the voltmeter with a 1-wire A-D converter that I can then read using OWW. Im guessing that the device I need is a DS2438 battery monitor. Assuming this is the case, it looks like the hobby boards solar detector uses this device - basically as I don't have facilities to deal with PCB making Id like to simply hook into an existing board if I can. So, if I am correct, how do I hook this compass detector into the solar detector?

Any thoughts welcome.


Thanks,

Gareth

ps - maybe this is something hobby-boards could consider as a new product line?

 

[BraveSirRobbin]

I couldn't find any info on the specifications of the A-D portion of the battery monitor, but make sure you consider voltage range and the number of bits measuring this span.

This statement particularly caught my eye on the site you referenced:

The output should vary by around 0.2 volts on a quiet day, so a 1 volt range should do nicely to get all but the largest storms

If you need any help on determining accuracy of an analog to digital device, you may want to reference THIS guide.

 

[ericvic]

The DS2438 has a resolution of 0.01V (10mV) and an error range of up to 0.075V (75mV) so reading a 0.2V change would be well within the specs of the DS2438.

If you would like I can help you figure out how to connect something up to one of our boards that have a DS2438. We may offer a generic board based on the DS2438 for applications like this one but I have no time frame for this to happen.

Eric

 

[g6ejg]

Thanks to you both for the comments.

Eric, I will take you up on the offer. However having hunted around a bit more I found a much better, if slightly more expensive, solution. This company http://www.speakesensors.com/ can supply a complete solution in kit form ( ie sensors, chips, pcb etc ) for a "proper" magnetometer - around £65 ( I guess thats around 130USD at the moment ).

What I need to do is contact them and get some idea of the voltage resolution required. Appears that the maximum voltage from this system ( ie for a full out, blow up your radio solar storm ) is 2.6volts.

Problem of course is that we are currently at the "bottom" of the solar cycle so it will quite a few years before we see the results!

Ill get in contact after the christmas holidays once Ive been intouch with Speake sensors to take you up on the offer.

Thanks, and merry christmase

Gareth

The DS2438 has a resolution of 0.01V (10mV) and an error range of up to 0.075V (75mV) so reading a 0.2V change would be well within the specs of the DS2438.

If you would like I can help you figure out how to connect something up to one of our boards that have a DS2438. We may offer a generic board based on the DS2438 for applications like this one but I have no time frame for this to happen.

Eric

 

[Skibum]

Hey Gareth

Thanks for the link. It seems we have a common interest.
I currently have alerts setup in Homeseer to that I get notified of any unusual activity.

 

[Skibum]

Don't forget any earth based magnetometer will only let you know WHEN it's happening, not when it's going to happen.
ACE will give you up to 60 minutes warning of an impending storm.
http://www.swpc.noaa.gov/rpc/costello/pkp_15m_24h.html