Step 6: Problems

Occasionally problems creep up.  A big problem popped up in this project when the first board was made.  No matter what was tried, the original design of having the board powered by button cell batteries with an on/off switch couldn’t work properly when finally assembled.  One of the problems wound up being an unacceptable voltage drop that made the battery source incompatible with one of the transistors chosen for the power circuit.  Many changes were tried to get the design to work, but nothing could be figured out without having to redesign the board, and since all of these boards were fabricated already, the decision had to be made to leave out the power circuit, give up on battery-sourced power, and requiring USB.  Very unfortunate, but this is why typically you order a small number of boards and work through some more testing.  Being short on time both because of the school year and free time led to the decision to hope it would work and get all the boards at once, and that gamble did not pay off.  The good news is that it works fine when plugged in to a power source via USB, so at least there is something to show for the project, even if it’s not 100% what the original design was for.  So as a result on the back of the board there are two pads for batteries and several smaller pads for the switch and other components (two transistors, two resistors, two diodes, and a capacitor).

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