Frequency Generator and Divider circuit

What are Frequency Generator and Divider Circuit?

A frequency generator is a circuit that generates a frequency and a divider circuit divides the generated frequency with various factors to get different frequency values. Various assembled frequency generators and divider circuits are available in the market but they are quite expensive to buy. The group of electronics geeks at dream lover technology designs a low-cost square wave signal generator and divider circuit. The frequency of 1 Hz, 10 Hz, 100 Hz, 1 kHz, 100 kHz, and 1 MHz are obtained at the output. The output pulse is selected by rotary switch SW₁ and fed to an output jack for output.

Circuit Description of Frequency Generator and Divider Circuit

The circuit of frequency generator and divider circuit is built around decade counter ICs (7490), hex inverter IC (7404) and of course crystal oscillator X_TAL1 of 10 MHz. IC₃ through IC₉ is a 4-bit ripple-type decade counter. A divide-by-two section and a divide-by-five section are formed for master/slave flip-flop internally in each IC 7490. In order to change the output stage of the counter on a high-to-low transition, each section has a separate clock input. The internal ripple delays do not change the output stage simultaneously. Therefore the decade output signals are subjected to decoding spikes and should not use for clocks or strobes.

In frequency generator and divider circuit IC₃ through IC₉ is configured as divide by-10 counters because the output of the divide-by-two section is not internally connected to the succeeding stage.

A crystal oscillator X_TAL1 with its associated circuits consisting of IC₂ (7404) and a few passive components generate a 10 MHz clock pulse. The output from pin 6 of IC₂ is given to pin 1 of IC₃, which divides it by 10 to give a 1 MHz clock pulse at its output pin 12. The 1 MHz clock pulse is fed to pin 1 of IC₄ and parallel output is connected to a pin of the rotary switch as shown in the circuit diagram. Similarly, the output from each decade counter is given to the input of the next stage as above up to IC₉.

The blinking of LED₂ indicates the output frequency. However, we can identify only 1 Hz and 10 Hz frequencies because above this frequency, the blinking rate is so fast that it is not possible to estimate the frequency.

Power Supply:- The input AC of 230V is stepped down to 9V using transformer X₁ which is further rectified by a full-wave bridge rectifier built using diode D₁ through D₄. The rectified output is further filtered using capacitor C₁ and is given to the input of IC₁ (5-volt regulator IC). The regulated 5V is obtained at output pin 3 of IC₁ and is indicated by glowing LED₁.

PARTS LIST OF FREQUENCY GENERATOR AND DIVIDER CIRCUIT