Nothing new - hall effect systems have been on the market for years http://sensing.honeywell.com/index.php?ci_id=3108&la_id=1&pr_id=4938 http://sensing.honeywe

Nothing new - hall effect systems have been on the market for years http://sensing.honeywell.com/index.php?ci_id=3108&la_id=1&pr_id=4938 http://sensing.honeywell.com/index.php?ci_id=3108&la_id=...