Power failure protection - memory jogger

Parts list 4 Resistors: R1,R1"= 560 n R2,R2" = 100 k R3,R3" = 56 St R4,R4" = 1 t Rg = 100 k (for bridge mode only) Capacitors: C1,C1",C6,C6" = 100 n C2,C2" = 10 p/16 V C3,C3" = 47 p C4,C4" = 220 p/16 V C5,C5" = 2200.t/16 V (not needed for bridge mode) C7 = 470 p/16 V C8 = 100 p/16 V CB = 100 n (for bridge mode only) Semiconductors: ICI = LM 2896-2 substituting wire links. Keep in mind that for high power applications the IC will require an adequate heat sink. A simple power supply can be constructed using the 7812 voltage regulator. For full output power into 4 SZ, a 1 amp supply is needed. Nothing can be worse than having even a brief collapse of the mains supply voltage when working with a system using volatile memory, like RAM. After the interruption, no matter how small, it will be apparent that the data in the RAM has well and truly evaporated. For that reason a lot of circuits are designed to side step the problem of either long, or short term, mains supply failure. The circ...