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Step 16The finished card
The picture shows my card, finished and playing back a squeaky version of "Go tell it on the Mountain". Anyway, it is recognizable as that tune, anyway. Anybody out there who knows better music than me is welcome to improve on this rendering.
When I was looking for a coin cell holder for the lithium cell I came across this set of three cells as part of an LED torch in a pen. Since three new cells will give around 4.5 Volts against the three volts available from a lithium coin cell this will be louder, when new, and so is adopted.
There should be a capacitor of about 0.1 microfarad across the supply terminals of the PIC. No difference was evident with new cells, but when I tried it with three rather 'tired' cells the music stopped and started stuttering half way through. So adding that capacitor will give you more playing time from the batteries.
When I was looking for a coin cell holder for the lithium cell I came across this set of three cells as part of an LED torch in a pen. Since three new cells will give around 4.5 Volts against the three volts available from a lithium coin cell this will be louder, when new, and so is adopted.
There should be a capacitor of about 0.1 microfarad across the supply terminals of the PIC. No difference was evident with new cells, but when I tried it with three rather 'tired' cells the music stopped and started stuttering half way through. So adding that capacitor will give you more playing time from the batteries.
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