We use saturated KNO3 for the bridge, yes, use filter paper,
electrodes must have very clean terminals and we use graphide, Zn, Ni, Cu and for the solution 0.1 M NaCl, CuSO4, ZnSO4.
Make sure your voltmeter is VERY sensitive, maybe use galvanometer, or mV, as the voltage produces is tiny.
Good luck
Lada
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