As the name implies, a simple frequency divider circuit is a circuit that accepts a signal at one frequency and produces a signal at a lower frequency.
This is accomplished by applying a certain element of manipulation to the incoming signal to lower its frequency.
Two widely available digital ICs may be used to construct a simple frequency divider circuit:
IC 4017 Decade Counter: With each clock pulse, the 10 outputs (Q0 to Q9) of this integrated circuit go high (logically 1) one at a time.
IC 555: This flexible IC is configurable in several ways.
Here, we will employ it as an astable multivibrator to produce a square wave signal that serves as the counters clock pulse source.
Circuit Working:
Parts List:
| Category | Item | Quantity | Power Rating |
|---|---|---|---|
| Resistors | 10k | 1 | 1/4 watt |
| 47k | 1 | 1/4 watt | |
| 330Ω | 1 | 1/4 watt | |
| R4 220Ω | 1 | 1/4 watt | |
| Potentiometer | 50k | 1 | – |
| Capacitors | Ceramic 10nF | 1 | – |
| Electrolytic 4.7μF 25V | 1 | – | |
| Semiconductors | IC 555 | 1 | – |
| IC 4017 | 1 | – | |
| IC 7805 | 1 | – | |
| LED (red) 5mm 20mA | 1 | – | |
| LED (green) 5mm 20mA | 1 | – | |
| SPDT switch | 1 | – | |
| Components | 9V Battery | 1 | – |
You may create a simple frequency divider circuit by connecting these two integrated circuits, whose working details are mentioned below:
Choosing the Frequency of Input:
An unique part known as a IC 555 is set up to function similarly to an astable multivibrator.
In essence, this indicates that a continuous square wave signal is produced.
This square waves frequency may be changed with a potentiometer, which functions similarly to a variable resistor knob.
A visual indicator is provided via an LED1 attached to the 555s output that blinks in accordance with the frequency produced.
Splitting the Wavelength:
The 555s square wave signal serves as the clock for the IC2 4017 counter, another component.
In essence, this chip counts the number of times the clock signal pulses.
We may regulate the reset behavior by using a switch to link the reset pin 15 of the same chip to specific outputs Q pins of the counter chip.
Division of Frequency by Two (f/2):
In this mode, the reset pin is linked to the counters second output pin, or Q2.
This is how it operates:
An LED2 that is attached to the counter may light up when the first clock pulse causes the counters output Q1 to become high (logical 1).
The counter is reset to its initial state (Q0 high) by the second clock pulse, which makes Q2 high.
As a result, Q1s high signal is essentially cancelled before it can finish a full cycle, resulting in an LED that blinks half as frequently as it did before.
Division of Frequency by Four (f/4):
The reset pin is linked to Q4, the fourth output pin, in this mode.
Before the reset from Q4 begins, the counter counts up to four pulses (Q0 high, followed by Q1, Q2 and Q3 high).
As a result, the frequency is divided by four and the LED attached to an output pin, such as Q1, lights up just once per four clock pulses.
In general, the counter chip in this circuit is used to selectively disregard specific clock pulses according to the selected output pin connection.
The frequency of the output signal is essentially lower than the input due to this ‘skipping’ of pulses.
The voltage is controlled by a IC3 7805 integrated circuit, lastly a 9V battery has been attached to power the circuit.
Formulas:
Here are the main formula and factors to take into account while designing an astable multivibrator for a frequency divider circuit, which usually uses parts like the IC 555:
Frequency of Oscillation fout:
The values of the resistors R1, R2 and capacitors C1, C2 define the oscillation frequency of an astable multivibrator utilizing the IC 555.
fout = 1.44 / (R1+2 * R2) *C1
where,
- The resistors attached to the IC 555 are R1 and R2.
- The timing capacitor that is attached to the IC 555 is represented by C1.
Duty Cycle:
The ratio of the outputs high time thigh to the waveforms whole period T determines the output waveforms duty cycle square wave:
Duty Cycle = thigh / T = R1+R2 / R1+2 * R2
Based on your unique frequency divider needs and the intended output frequency range, change the component values.
You may use the IC 555 to create an astable multivibrator circuit that is appropriate for frequency division applications by applying these calculations and considerations.
How to Build:
To build a Simple Frequency Divider Circuit follow the below mentioned steps for connections:
- Assemble all the components as mentioned in the above circuit diagram.
- Connect pin 1 of IC1 555 to ground.
- Connect pin 2 to pin 6 of IC1 555 through capacitor C1.
- Connect pin 3 of IC1 555 to pin 15 of IC2 4017.
- Connect pin 4 and pin 8 of IC1 555 to positive supply of +9V battery.
- Connect pin 5 of IC1 555 to ground through capacitor C2.
- Connect resistor R2 between pin 7 of IC1 555 and to upper leg of VR1 pot.
- Connect resistor R1 between pin 7 of IC1 555 to positive supply.
- Connect a resistor R3 and LED1 in series from pin 3 of IC1 555 to ground.
- Connect pot VR1 one leg to resistor R2 and other leg to pin 2 and pin 6 of IC1 555.
- Connect pin 2 of IC2 4017 to ground through resistor R4 and LED2 in series.
- Connect pin 4 of IC2 4017 to third leg of SPDT switch.
- Connect pin 8 and pin 13 of IC2 4017 to ground.
- Connect pin 10 of IC2 4017 to 1st leg of SPDT switch.
- Connect pin 14 of IC2 4017 to pin 3 of IC1 555.
- Connect pin 15 of IC2 4017 to center leg of SPDT switch.
- Connect pin Vin of IC3 7805 to positive supply of 9V battery, connect GND pin of IC3 7805 to ground, and connect pin Vout of IC3 7805 to a positive supply of IC1 555 circuit.
Safety Measures:
- To prevent shorts or malfunctions, make sure all connections are tight and adhere to the circuit design.
- A live circuit should never be left unattended, particularly if it is linked to other equipment.
- It is always preferable to seek advice from someone with more expertise or use trustworthy internet resources when in doubt.
- You can reduce the possibility of mishaps when working with your frequency divider circuit by adhering to these procedures.
Conclusion:
The simple frequency divider circuit use a 555 IC to produce a signal with a changeable frequency, and a IC 4017 counter chip to selectively ‘skip’ pulses within the signal.
We may adjust the number of pulses that the counter counts before restarting by connecting a certain output to the reset.
Depending on the selected output, this essentially splits the original frequency by a factor of 2, 3, 4 etc.
This is an easy to use method for learning frequency division with common integrated circuits.