Digital decoder for PLL

In the example of the use of TTL IC this time, we will try to submit a design Switch to set UPDOWN operating frequency of a PLL which uses TC 9122. First we will take the IC 7400 to create two inputs to the flipflop as the following counter is 74192.

Figure 1.Updown digital switch

With the above design, when the UP button is pressed, IC1 will count forward, and the calculation results will be issued as a Binary coded Decimal via pin 3, 2, 6 and 7. If the count at IC1 has reached 10, it will give one IC1 to IC2 pulses that will calculate forward IC2 and IC1 ONE count back to ZERO. BCD output is then used as input to the PLL to adjust the working frequency.

Figure 2.Seven segment display

If the output is sampled and used as input to the IC 7447 to turn 7 segment, the results of this calculation can be displayed.