Simple beeper circuit using oscillator CD 4093

Several electrical appliances we come across make a small “beeping” sound at various times while they are switched. Devices such as computers, heaters, LCD televisions, microwaves etc. are commonly found to make a small beeping sound. These small sound signals are heard either during the time when they are switched ON or OFF or at regular intervals of their operation.

These beeping signals are hardly a second or two long enough, but are a major necessity for engineers as it signifies successful completion of certain process in the gadgets. Also, the beeping sound also acts as a reminder in several gadgets too.

This beeper circuit can be used as a power on reminder if heavy current devices like heater, electric iron etc are switched on. It gives short beeps once in every five minutes to remind the power on status. It is just like the beeper circuit used in UPS.

Circuit working

CMOS IC CD4093 is used as a simple oscillator using its gates. Resistor R1, R2 and capacitor C1 determines the On / Off time of the oscillator. With the given value of R2 and C1, the Off time is around 5 minutes and with the value of R1, the On time is around 2 seconds. This timing can be changed by varying the values of R2, C1 and R1. In short, if the value of R2 is high, Off time will be high and if the value of R1 is low, the On time will be low. Value of C1 determines the total On/Off timing of the oscillator.

CD4093

Fig. 1: Pin Diagram OF CD 4093 IC

The circuit can be powered using a 6 volt adapter power supply. If it used as power on reminder, the AC to the power supply should be tapped from the power lines of the device to be monitored. So when the switch turns on, both the device and the power supply of beeper gets power.

Components

Resistors

R1 120K, R2 4.7M, R3 2.2M

Capacitors

C1 470 uF 25 V, C2 0.1

Diodes

IN4148

Integrated Circuit

CD4093

Buzzer, 6V Power supply