Flip Flop Lab Report

Abstract

The aim of this experiment was to investigate the operation of simple logic gates and flip flops. We also investigated how simple counters can be constructed. To do this we used a TTL logic system provided in the lab with a +5V signal consisting of NAND and NOT gates. Using these simple gates we were able to construct circuits corresponding to AND, OR, NOR, XOR and XNOR gates. Our truth tables were as tabulated in Tables 1-8 (results section) which verified the operations of simple logic gates and flip flops (Table 9). We were also able to construct a counter to scale of 16 and 10 (Tables 10 & 11) and examined how scales of 12, 4 and 5 could be produced, conclusions of which are presented in the results section.

Introduction and Theory

Digital electronic circuits are often made from assemblies of logic gates. These represent signals as discrete levels instead of a continuous range. In Boolean Algebra these two levels correspond to the levels ‘1’ and ‘0’. Logical 1 is when there is a signal present and logical 0 when no signal is present. Logic gates are made up or combinations of these signals and

The output gate of a flip flop is often fed back into the input as we can see from Figure 2. This reliance on the concept of feedback is what makes the flip flop capable of storing it’s previous state. In this experiment we used a clocked master slave flip flop. This is actual a combination of 2 flip flops the ‘master’ and ‘slave’ as we can see in Figure 2. The clock produced an alternating +5V - 0V pulse and the flip flop only changes state when the clock pulse is changed. The flip flop only changed state when the clock returned to zero, this is because the clock pulses go through a NOT gate to the ‘slave’ flip flop. Until the clock changes the flip flop is able to maintain whatever state it was previously in, this concept is often used for RAM in