reversed-functioned scr
JFETs and depletion-mode MOSFETs have the characteristic of being &quot;on&quot; with no voltage applied and they will turn &quot;off&quot; when a negative voltage is applied to the gate (N-channel devices).
They do not, however, have the &quot;latching&quot; characteristic of thyristors. Available devices are also fairly limited in current-handling capability, in the 10A range, and higher voltage devices are capable of much less current.