book page reminder

elektor july/august 1980 UK 15 106 book page reminder How many times have the lights gone out when you are halfway through the best part of your "whodunnit"? Or perhaps your spouse can no longer sleep with the reading light on? How do you mark your page without bending it when your cuddlesome canine friend has chewed your favourite imitation leather bookmark? These questions together with the fact that nobody likes to deface their books (do they?) were the motivation for designing this very simple and easy to operate book page reminder. When not being "programmed" the majority of the circuit is switched off and the only parts that draw current are three decoder/driver ICs (IC2 . 1C4). As these are CMOS ICs the actual current consumption will be very small. Operation of pushbutton switch S1 causes the numerical page information to be displayed on the three seven-segment LEDs. The oscillator formed by N1 ... N3 is also supplied with power via S1, but although it starts up the decode...