Hi all,
We process plastics and I want to detect sub-micron ferromagnetic particles in the plastic. My first thought is a Helmholtz design where one coil can be driven by a switching circuit and the other coil a pick-up. The ferrite should increase coupling and my pick-up saw tooth amplitude would change. I could drive a MOSFET gate and divide the gate with a pot to set a threshold. When the amplitude was reached, to trigger the gate, a PIC that is driving this circuit would light an led.
A sine wave driving the primary 24VAC 60Hz may work well as I am only looking for a change in amplitude. I once used a PIC to "look" at a sinewave amplitude by measuring the "on" time of the upper sine wave. I only needed a series resistor to protect the PIC. I think I remember the PIC having a built-in diode.
I need a detection area with about 2"' diameter and 1" separation. One part size is about 1" x 1" and the other is a disc that could be rastered like a record player with a Helmholtz clamp. Any thoughts on what sensitivity I could expect? Is there a better design I am missing?
We process plastics and I want to detect sub-micron ferromagnetic particles in the plastic. My first thought is a Helmholtz design where one coil can be driven by a switching circuit and the other coil a pick-up. The ferrite should increase coupling and my pick-up saw tooth amplitude would change. I could drive a MOSFET gate and divide the gate with a pot to set a threshold. When the amplitude was reached, to trigger the gate, a PIC that is driving this circuit would light an led.
A sine wave driving the primary 24VAC 60Hz may work well as I am only looking for a change in amplitude. I once used a PIC to "look" at a sinewave amplitude by measuring the "on" time of the upper sine wave. I only needed a series resistor to protect the PIC. I think I remember the PIC having a built-in diode.
I need a detection area with about 2"' diameter and 1" separation. One part size is about 1" x 1" and the other is a disc that could be rastered like a record player with a Helmholtz clamp. Any thoughts on what sensitivity I could expect? Is there a better design I am missing?