( A ( ( voltmeter ( -LRB- ( ( ( signals ( in ( electronic circuits ) ) ) ( usually ( produce ( voltage changes ) ) ) ) -RRB- ) ) ) . ) )
(ROOT (S (NP (NNP A)) (VP (VBP voltmeter) (PRN (-LRB- -LRB-) (S (NP (NP (NNS signals)) (PP (IN in) (NP (JJ electronic) (NNS circuits)))) (ADVP (RB usually)) (VP (VB produce) (NP (JJ voltage) (NNS changes)))) (-RRB- -RRB-))) (. .)))
A voltmeter (signals in electronic circuits usually produce voltage changes).
(ROOT (S (NP (NNP Voltage)) (VP (VBZ is) (ADJP (RB continuously) (VBG changing) (PP (IN within) (NP (NP (DT a) (NN circuit)) (PP (IN in) (NP (DT an) (JJ analog) (NN signal))))))) (. .)))