electronic pocket pinball

61 H.J. Walter N2 4 69 electronic pocket-pinball This highly portable pocket-pinball game may not exactly be a substi- tute for its big brothers in the amusement arcades, but it still provides a lot of fun. The circuit is relatively simpte: three CMOS ICs, nine LEDs, six resistors, one capacitor, one push- button and a 9 V battery. Together with R1, R2 and Cl, NOR gates Nl ... N3 form a clock generator whosesignalisappliedtodecimal counter IC3. For as long as the player presses pushbutton Si, clock puises are counted. When the button is released, the counter is inhibited for the incoming clock signals and only one of LEDs Dl ... D7 will light. The carry output of the decimal counter toggies flip-flops FF1 and FF2 which are configured as 2-bit binary counters. Depending on the counter status, the player is entitled to a free bal] (LED D8lights) or he can double the score (LED D9 1ights). Obviously, this simple circuit is not equipped with a points counter. The points gained by each...