Control circuit for electrical household appliance - has start and cancel function keys connected to electronic circuit with three flip=flop(s)

摘要

The control unit is designed for programmable household electric equipment and has a safety feature incorporated to ensure correct re-setting if the keyboard is incorrectly programmed, e.g. by children. There are two input keys, one (1) for a cancel function and another (2) for a start function, each connected through a hysteresis-type Schmitt trigger (3, 4) in parallel with an RC-type timing circuit (5, 6, 7, 8). The start key function key circuit is connected to the R terminals of two D-type flip flops (12, 13). The cancel function key circuit is coupled through a logic element with an AND gate (16) and an OR gate and a monostable flip-flop (15) to the output lead (14) to the programmable electrical unit.