Velleman projects K8049 Assembly instructions - Manual (Page 7)

7
Now place the battery contacts into the housing on their right places.
Connect now the wire that you earlier have mount to the negative battery lip.
Connect a jumper between the positive battery lip and positive connection on the pcb.
Construction
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2
3
4
Positive battery lip
Common battery lip
Common battery lip
Negative battery lip
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2
3
4
Negative battery lip
Positive battery lip
FIG. 8.0