Timer for Students

The Timer for Students circuit is capable of sounding an alarm after a preset time period and also gives out a few beeps at half-time. The time period after which the alarm sound is to be generated can be easily programmed to suit a specific requirement. No. of ICs used: 2 The heart of the circuit is the 14 stage binary counter IC CD4060 (IC1) and the NE555 (IC2) timer IC. The CD4060 has a built-in oscillator and a 14 stage divider wherein the basic oscillator frequency is divided by 16384. The circuit allows for the oscillator frequency to be set using potentiometer VR1 (in series with a resistor (R1)) and a capacitor (C1). Potentiometer VR1 is adjusted for a time period of 15 minutes at output Q12 (pin2). The output Q13 (pin 3) will go HIGH after 30 minutes. When Q13 goes high, the 3-terminal piezoelectric buzzer becomes active and gives out a tone. This buzzer also beeps at half the time for a few seconds. NPN transistor BC547 (T1) prevents further oscillations after the lapsed time. A red LED (LED1) is used as activity indicator. Pressing the reset button momentarily pulls all the internal counters of CD4060 to zero and the timer starts again. The timer is reliable, accurate, and consumes about 10 mA of current when the buzzer is active. learning: Application of 14-stage binary counter IC CD 4060. Application of the NE555 timer IC. Brand: Kits'n'spares, Marketed by: Kits'n'spares