Experimental principle

In logical algebra, there are three basic logical operations: and, or and not. As shown in Figure 1, the control circuit of three indicator lights is given. In the circuit of Fig. 1 (a), the indicator light will be on only when two switches are closed at the same time. This causal relationship is called logic and; In the circuit of Fig. 1 (b), as long as any switch is closed, the indicator light will be on. This causal relationship is called logic or; In the circuit in Figure 1 (c), the light is on when the switch is off, but not when the switch is closed. This causal relationship is called logical non. Figure 2 shows the corresponding graphical symbols.

Drawing

The circuit is a DC power supply, so a DC voltmeter should be used

Experimental report

Experimental content

Fig. 4 is a NAND gate, or gate and not gate test circuit, which recognizes the operation of logic and (NAND), or and non from the relationship between the input and output levels of the logic gate.

Set the level value / logic value of the input signal in turn according to table 1, measure the level value of the output signal f with a DC voltmeter, write the corresponding logic value and fill in Table 1. Write out the logical relationship between F and a and B according to the measurement results.

NAND gate

2. Set the level value / logic value of the input signal in turn according to table 2, measure the level value of the output signal f with a DC voltmeter, write the corresponding logic value and fill in Table 2. Write out the logical relationship between F and a and B according to the measurement results.

Or gate

3. Set the level value / logic value of the input signal in turn according to table 3, measure the level value of the output signal f with a DC voltmeter, write the corresponding logic value and fill in Table 3. Write out the logical relationship between the output signal and the input signal according to the measurement results.

Non gate

Experimental report:

1. Build the circuit, complete the above experiments, and supplement complete tables 1 ~ 3;

2. Write out the logical relationship between the output signal and the input signal according to the measurement results.

NAND gate: F = (AB) ‘or gate: F = a + B not gate: F = a’