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Earth Resistivity Meter PCB problem?

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  • Earth Resistivity Meter PCB problem?

    Has anyone built the ERM as described in the EPE article and had it work? I was just looking at the mask for Board 1, and there seems to be a mistake in the layout. He has Tr3 and Tr4 (TIP30 and TIP29 power transistors) connected as though their pinout is CBE (like a TO92 package), but they are TO220 packages, and so their pinout should be BCE. The given PCB would then switch the connections to the collector and base of both of these transistors, which should not work too well! Am I correct about this error?

    Judging from the spaghetti in the photo of his prototype, I would guess that he never actually made and connected these PCBs to see if they work, so there may be other mistakes there as well that I have not noticed yet.
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