An Automatic Electronic Frequency Comparator

Abstract

The Automatic Electronic Frequency Comparator unit consists of two Electronic Digital Clocks, one running on a stable crystal oscillator treated as a ‘Standard Frequency Clock’ the other running on mains supply frequency known as ‘Mains Frequency Clock’ and an ‘Integrated Frequency Time Difference Unit’ which displays instantaneous time difference between the two. This difference is precisely the same as the cumulative effect of the difference in the frequency over a desired period.

Comparison of the two timings is basically executed by counter method. First, the mains time is compared with the Standard time for polarity. The minutes and seconds of the larger time pass into a 16-bit storage shift-register while those of the smaller time enters into a counter chain. A series of pulses is then allowed to pass through the counter chain and a display counter till the contents of the shift-register and the counter chain are exactly identical. The stored pulses in the display counter are then decoded and displayed on an indicator, which gives the difference in the two times with polarity.

The unit has very wide applications in the power systems, where control over the frequency can be exercised on the basis of visual indication. By making the comparator time difference nearer to zero, the supply frequency can be averaged out closer to the standard frequency over a 24 hour period. The unit uses 100% indigenous components.