Basic TTL Tri-State Buffer Circuit Example 1
Fig. 1

Basic TTL Tri-State Buffer Circuit Example 1


This is an example tri-state buffer circuit. The output is turned on-off based on the logic level on the enable pin.

Note the truth table in Fig. 2 below.

Another variation is Basic TTL Tri-State Buffer Circuit Example 2. This differs in that we eliminated the SN74LS02 circuit. We can use a ingle IC instead of three differing ICs.

The two are functionally identical

Tri-State switch truth table.
Fig. 2

Tri-State switch truth table. This illustrates a non-inverting output.

When the enable pin (EN) is LOW the output is floating.

Pin diagram SN74LS00 quad 2-input NAND gates.
Fig. 3

Pin diagram SN74LS00 quad 2-input NAND gates.

SN74LS02 quad 2-input NOR gates pin connections.
Fig. 4

SN74LS02 quad 2-input NOR gates pin connections.

SN74LS04 internal diagram.
Fig. 5

SN74LS04 internal diagram.

H-bridge motor control based on tri-state switches.
Fig. 6 H-bridge motor control based on tri-state switches.

View all of my You Tube Videos
Also visit and subscribe to My YouTube Channel