One such circuit turns 100 years old in June, which is surprising because it literally is the building block of every computer. It’s the flip-flop ... various flavors (JK-, SR-, D-, and T ...

The circuit has a fairly simple explanation. U1 is a counter. Figure 1 A Flip ON Flop OFF circuit for DC voltages. The gadget is connected to the output terminals of the PB. With an adequate heat sink ...