I've built a fantastically simple circuit which uses a magnetic reed switch an an IRFB7546 to switch 12VDC from a battery pack to a resistive load. It works on the breadboard, but not in the PCB version, though I think they're identical.
This is the circuit diagram from Eagle:
I have bread-boarded this, and the breadboard version on my workbench behaves precisely like I would expect it to. I have also produced a real board (thanks OSH Park!) from this design. Here's the board, also from Eagle, as manufactured by OSH.
As far as I can tell, it appears that my produced board matches my breadboard, which matches the circuit diagram that I have produced. But the circuit doesn't work:
- Expected behavior: passing a magnet near the magnetic reed switch should switch power, such that I should have 0VDC on output normally, and 12VDC on output when a magnet is near the switch.
- Achieved behavior: 12VDC is always provided to the output. The magnetic reed switch shows high resistance (~10Mohm) normally, and low resistance (<1ohm) with magnet nearby.
What am I doing wrong? What things can I look at to try to refine this problem?
Thanks,
Dan
This is the circuit diagram from Eagle:
I have bread-boarded this, and the breadboard version on my workbench behaves precisely like I would expect it to. I have also produced a real board (thanks OSH Park!) from this design. Here's the board, also from Eagle, as manufactured by OSH.
As far as I can tell, it appears that my produced board matches my breadboard, which matches the circuit diagram that I have produced. But the circuit doesn't work:
- Expected behavior: passing a magnet near the magnetic reed switch should switch power, such that I should have 0VDC on output normally, and 12VDC on output when a magnet is near the switch.
- Achieved behavior: 12VDC is always provided to the output. The magnetic reed switch shows high resistance (~10Mohm) normally, and low resistance (<1ohm) with magnet nearby.
What am I doing wrong? What things can I look at to try to refine this problem?
Thanks,
Dan