When the momentary push-button (PB) switch is closed, 12V from C3 is applied at A, causing T2 to turn on. This state grounds the Reset bus, turns on PFET T4 by putting V gs(on) on its gate through the ...

Figure 1 Circuit converts momentary action push switch into latching power switch.. To understand how the circuit operates, assume that the DC power supply, +V S, has just been applied, capacitor C1 ...