# Simple astable multivibrator circuit using CD4047 Cmos IC

When we say to the an astable multivibrator circuit, Many people will think to Many people think of as the most IC-555. But this time, it is recommended circuit in Figure 1. Which use IC-4047 CMOS with ability of this nature as well. And the advantage is, That output will be a square wave, which has three forms are: First at pin 13 of IC1 will be basic frequency, Second is pin 11 will be Is half that of basic frequencies, And thirdly at pin 10 is half the frequency of basic frequency. but will has to invert the signal to 180 degrees. So is there a characteristics opposite to the second output.

Figure 1 the Simple astable multivibrator circuit using CD4047 Cmos IC

This circuit yet cannot adjust duty cycle. So sorry, if one were to try to use the adjusted duty cycle. But output of IC will have duty cycle of 50% makes has symmetry exists. For the controller frequency will be serves as VR1 and C1. By the value of VR1 is used in a range of 1 KHz to 1 MHz. To Adjust to the desired frequency. The C1 will determine the frequency. The value used to determine the various range. Can see from the table below. And should select capacitors that have low leakage.To waveform distortion and frequency can not be much.

The value of C1 in circuit as Figure 1 to determine the frequency use.
1uF = 1-10Hz
0.1uF = 10Hz-1kHz
0.01uF = 100Hz-10kHz

How to builds
This project is a few components so can put on the universal PCB board as Figure 2. And be carefully for wiring,the polarity of the electrolytic capacitors, Pin of the IC.

Figure 2 the components layout of this projects

Components list
The potentiometer
VR1______See in text
Capacitors
C1_______See in text
Semiconductor
IC1______CD4047____Low Power Monostable Astable Multivibrator
Other components
Socket 14 pin, The universal PCB board.

## 12 thoughts on “Simple astable multivibrator circuit using CD4047 Cmos IC”

1. RURANGIRWA BOSCO says:

why is it that the wave signals of pin10 and 11 are looking differently from pin13

2. RURANGIRWA BOSCO says:

why is that pin 10and pin11 are looking differently from pin13

3. hema says:

the reason is that the pin13 shows the basic frequency derived by the VR1 and C1 across pins 1,2 & 3. The pin10 & pin11 shows the half frequency of the original frequency at pin 13. the two frequencies at pins 10 & 11 are of inverted to each other phase. that is 180 degrees out of phase.

4. Hi, hema
You are good man.

where is the Value of VR1??

6. vivek says:

I want use this IC for inverter. may i know How to program this IC?

7. @RURANGIRWA BOSCO..Pin 10,11 Freq is divided by 2 @vivek The 4047 is a Cmos Multivibrator and not a PIC,,,, You can’t Program it,See 4047 Data Sheet For More Info!!! Pin 10 11 are Inverted Outputs

8. To determine R and C use the Formula F=1/8.8RC..I would select a Value of C and then calculate R This Formula is For The F/2 outputs whereas F output F= 1/4.4RC is for the F Output..I would use the 1/8.8RC Formula as I would Get The 50% duty Cycle!! Worked With This Chip Long Time ago

9. Pankaj chauhan says:

VR1 is connected beween 1 to 3 pin.

10. nima says:

what is the difference between ic 555 and ic cd4047?

11. nima says:

what is the use of c1 and vr1 in pin no 123?

12. Dear says:

What max frequency can 4047 attain on pin 10 & 11, and for the formula f=1/(8.8*rc) should “r” be considered in ohms and capacitance in microfarad or farad. For eg. if r=1k and c=0.1 mfd.
I want the frequency in between 20khz-28Khz………..Plz……