The device working principle of the circuit shown in Figure 2. Where TP is the touch of metal films, usually as TP, a, b is interrupted, the equivalent of LSE of 1, 2 was left open between the legs, so the LSE’s 4 pin output low, the relay J is the release of the state, which often j break open contacts, the motor M does not work. When the fingers on the TP a, b when the two connected, LSE’s current output 4 feet, then pull-J excitation, the contact j is closed, the motor M connected to the power, so the motor M operation. After the release hand, M is stopped. TP can Bonded Copper silver production.