摘要 |
A fail-safe solid state logic system based on the use of an AC input signal of one type, and a DC input which causes a logical gate to convert the AC input signal to a totally different AC output signal; that is, to one adapted to be received by a vital driver or the like, which is tuned to accept only that different AC output signal and no other. Accordingly, the failures which are most likely to occur, namely, shorts from input to output or failure to toggle, result in the AC signal frequency not being changed and as a consequence, the system fails safe. |