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A project log for Wi-Fi Controlled Open Scoreboard

A open design for a portable scoreboard that can be controlled over Wi-Fi, and integrated into event management software.

Christopher KratzChristopher Kratz 01/24/2015 at 17:250 Comments

just doing some casual testing of my driver board. The low side MOSFETs worked perfectly, on with a low input to the opto coupler, and off when that input goes high. However, the high side FETs had a slight issue, the were mostly on by default and then all the way on with the high input to the coupler. Uh oh. Well looking online at some reverence designs showed I wired the P channel FET wrong, swapping the gate and the source pins. I think this explains the behavior, as my mostly on condition was about 1.2 volts below Vcc, which I think would be the forward biased drop off the body diode. Not all is lost though, by carefully removing the FET, flipping it upside-down, and rotating it I was able to get two pins soldered to the right pads, and run a fine wire to the gate. 16 times. I've got about 6 left and I used up my two spares. Desoldering these with the iron is tough, as the lightest pull will rip the pin out of the package. Tests on the fixed FETs succeded, though. I'll have to update the schematic and board layout when I can.

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