Timer With Musical Alarm
Timer With Musical Alarm
Many timer based project is already published by group of dreamlover technology in this website. Now, Timer with musical alarm is a simplest timer based project using CMOS oscillator in the series of timer circuit, can be adjusted from the delay of one minute to two hour and a musical song is heard after time period is over.
Circuit Description of timer with musical alarm
The circuit timer with musical alarm use famous CMOS oscillator/divider IC (IC1 ). Although this circuit operates in 9V its standby current drain is very low. The time delay of timer circuit can be adjusted by adjusting the preset VR1. The base of npn transistor T1 is connected to pin 3 of IC1 through resistor R4 and its emitter terminal is connected with pin 2 of melody generator IC (IC2) in order to provide positive supply when adjusted time delay is over. Here the zener diode ZD1 is used as regulator which reduce power supply to required for operation of IC2 i.e. 3.3V. Lastly for music output the output from pin 1 of IC2 is fed to loud speaker via driver transistor and its volume is controlled by preset VR2. For starting the timer power is supplied by pressing switch SW1.
Parts list
Resistor (all ¼-watt, ±5%)
R1 = 1.2 MΩ
R2 = 2.2 MΩ
R3 = 56 KΩ
R4, R5, R6 = 1 KΩ
VR1 = 1 MΩ
VR2 = 1 KΩ
Capacitors
C1 = 0.01 µF
C2 = 0.22 µF
C3 = 1 µF/25V
Semiconductors
IC1 = CD4060 (CMOS oscillator /divider IC)
IC2 = UM66 (melody generator)
T1, T2 = BC547
Miscellaneous
SW1 = on/off switch
9V battery
LS1 = 8Ω, 0.5W speaker
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