This presentation discusses basic logic gates used in digital electronics. It explains that a logic gate either allows a signal to pass through or stops it, and there are three main types: AND, OR, and NOT. Examples are given for each gate, such as an OR gate triggering a doorbell if either the front or back doorbell switch is pressed, and an AND gate activating a burglar alarm only if both the person sensor and alarm switch are on. A NOT gate inverts the input signal.

1. Presentation
153-19-1822
A B D U L L A H - A L - M A M U N
Department Of ETE
Digital Electronics

2. LOGIC GATES
AND GATE OR GATE NOT GATE

3. A logic gate is a digital circuit which either allows a
signal to pass through it or to stop it.
There are three basic logic gates: AND, OR and NOT.
AND GATE OR GATE NOT GATE

4. OR GATE
A
B
X
INPUT
OUTPUT
INPUT
The output will be positive (True) if at least one input is true.

5. OR GATE
Front Doorbell Switch
Back Doorbell Switch
Doorbell
ON/OFF
ON/OFF
ON/OFF
If either the Front Doorbell Switch
OR the Back Doorbell Switch is
pressed then the Doorbell rings.

6. AND GATE
A
B
X
INPUT
OUTPUT
INPUT
The output will be positive (true) when both inputs (the input one AND the input two)
are positive (true).

7. AND GATE
Person Sensor
Alarm Switch
Burglar Alarm
ON/OFF
ON/OFF
ON/OFF
If both the Person Sensor AND
the Alarm Switch are on then the
Burglar Alarm is activated.

8. NOT GATE
A XINPUT OUTPUT
A NOT gate (inverter) has only one input. It reverses the logic state.

9. NOT GATE
Temperature Detector
(Above 20°C)
Central Heating
ON/OFF ON/OFF
If the temperature is above 20°C
then the Central Heating is
switched off.
If the temperature is below 20°C
then the Central Heating is
switched on.

10. Thank You For Your Time