Crystal Oscillator Frequency Converter

Figure 1 

The circuit was designed to create a frequency convert with the use of a crystal oscillator for the conversion of 10 MHz to 1 MHz.

• 7404 – a hex inverter utilizing TTL to achieve high speed at nominal power dissipation and is normally compatible with other 74 series devices with features such as 10 fan-out, 400mV guaranteed noise immunity, 10mW average power dissipation, 12ns average propagation delay, 4.75V to 5.25V allowable power supply variation, 1V typical noise immunity, and input clamping diodes
• 7490 – a monolithic BCD counter that contains four master-slave flip flops and additional gating to provide a divide-by-two counter and a three-stage binary counter for which the count cycle length is divide-by-five with a gated zero reset and gated set-to-nine inputs for use in BCD nine’s complement applications
• Crystal Oscillator – an electronic circuit made of one or more crystals or quartz located in the feedback loop circuit where its physical characteristics determine a particular designed frequency where electrical oscillations are produced

The frequency oscillator is made up of a solid quartz crystal which is made up of components that are packed in a regularly order such as its atoms, ions, or molecules, while it extends in all three spatial dimension for its repeated patterns. They may be used for operation in either parallel or resonant condition. The primary considerations are the stability and accuracy when choosing this fixed frequency oscillator. With appropriate transducers, any object that is made of an elastic material may be utilized as a crystal since all objects have vibration with natural resonant frequencies.

The construction of the circuit results to an oscillator with a frequency of 10 MHz, which is made possible by the functions of the hex inverter 7404 as denoted by IC1A and IC1B together with a frequency divider being performed by the monolithic BCD counter 7490. The pulses are divided to 10 using the IC2 while IC1C acts as a buffer. A buffer can be considered as a single-input device which has a gain of 1 that mirrors the input at the output.

During the operation, the oscillation is being sustained by the crystal oscillator by taking a voltage signal from a quartz resonator. The signal is fed back to the resonator after being amplified. In this circuit, the frequency is being micro tuned by the presence of 39 pF variable capacitor. The 1 MHz converted frequency can be obtained from the pin 12 of IC2 as it serves as its output. Based on the components used in the circuit, it will no longer require additional adjustments for the circuit to function well.

One of the uses of crystal oscillator frequency converter is on the field of printer production to achieve the desired number of pages to be printed with a certain amount of frequency. The concept of the circuit is being applied by Epson, HP, and other printer companies. They are also used in some applications to change the output frequency from one value to another value.

Source:users.otenet.gr/~athsam/10_to_1mhz_frequncy_converter.htm