Like in a scr say in thyristors or triacs we know we can turn the scr "on" after a certain anode-cathode break-over voltage depending on the current present at the gate.But I want to know whether there is device or circuit which remains off if the applied voltage is greater than the specified voltage value according to the device and it will turn "on" if the applied voltage goes below that of pre-specified voltage value. In other word its a reversed-functioned SCR. (I do not care whether it is unidirectional of bidirectional)
JFETs and depletion-mode MOSFETs have the characteristic of being "on" with no voltage applied and they will turn "off" when a negative voltage is applied to the gate (N-channel devices).
They do not, however, have the "latching" 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.