the present invention relates to an instrument for the selective coagulation and dissection of biological tissue. the instrument comprises a tool (29) with coagulation electrodes (36) and at least one cutting electrode (38). the electrodes (36, 38) are activated by means of an operating circuit (45). the operating circuit (45) comprises an evaluation circuit (70), to which an external device (21) delivers an evaluation signal (s) with first half waves (s1) and second half waves (s2). the first half waves (s1) and the second half waves (s2) have opposite polarities. during at least a first half wave (s1), the evaluation circuit (70) checks whether a first switch (32) or a second switch (33) or whether both switches (32, 33) are activated on the instrument (26) . depending on the evaluation result, an activation signal (a) is generated and transmitted to a switching unit (53). depending on the activation signal (a), the switching unit (53) is switched to a first switching state or a second switching state. in the second switching state, adequate voltage for dissection and current suitable for dissection, correspondingly, are not applied to the cutting electrode (38). in the first switching state, a voltage suitable for dissection or a current suitable for dissection is applied to the cutting electrode (38).a presente invenção refere-se a um instrumento para a coagulação e dissecação seletivas de tecido biológico. o instrumento compreende uma ferramenta (29) com eletrodos de coagulação (36) e pelo menos um eletrodo de corte (38). os eletrodos (36, 38) são acionados por meio de um circuito de operação (45). o circuito de operação (45) compreende um circuito de avaliação (70), para o qual um aparelho externo (21) entrega um sinal de avaliação (s) com primeiras meias ondas (s1) e segundas meias ondas (s2). as primeiras meias ondas (s1) e as segundas meias ondas (s2) possuem polaridades opostas. durante pelo menos uma primeira meia onda (s1), o circuito de avaliação (70) v
