For example, a transistor is a controllable switch, but it is directional between the collector and emitter, and it has interactive control between the base and emitter.
例如，晶体管是可控的开关，但它在集电极和发射极之间是定向的，并且在基极和发射极之间是配合控制的。
2
A proportional directional valve however will be controlled by an electrical device more like a dimmer switch.
一个比例方向阀是由与一个与调光开关非常象的电设备控制的。
3
Drag onto the page to add a thyristor, bi-directional triode-type, triac-gated switch.