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Decodificador De Nombres 7 Segmentos

Arduino
Photo of Decodificador De Nombres 7 Segmentos
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VASCONCELOS SANCHEZ CHRISOFER RICARDO

Published October 18, 2026

This project builds a hardware-based 7-segment display decoder using TTL logic gates to convert binary input signals directly into the correct segment patterns for displaying characters. The decoder uses a combination of inverters, AND gates, and OR gates to implement the logic necessary for character recognition and display control, operating entirely in hardware without requiring a microcontroller.

The guide provides a complete wiring diagram showing how to connect the 74LS series logic ICs on breadboards, a full parts list with all resistors and components needed, step-by-step assembly instructions for organizing the TTL circuits, and details on connecting the four binary inputs and eight 7-segment outputs. Builders will learn how combinational logic circuits can solve real-world display problems and gain hands-on experience with classic digital electronics components.

Wiring diagram

Gather all the parts

QtyComponent
1

74LS04 hex inverter (U1)

Integrated circuit containing six TTL NOT gates.

1

74LS08 quad AND gate (U2)

Integrated circuit containing four two-input TTL AND gates.

1

74LS08 quad AND gate (U3)

Integrated circuit containing four two-input TTL AND gates.

1

74LS08 quad AND gate (U4)

Integrated circuit containing four two-input TTL AND gates.

1

74LS08 quad AND gate (U5)

Integrated circuit containing four two-input TTL AND gates.

1

74LS08 quad AND gate (U6)

Integrated circuit containing four two-input TTL AND gates.

1

74LS08 quad AND gate (U7)

Integrated circuit containing four two-input TTL AND gates.

1

74LS08 quad AND gate (U8)

Integrated circuit containing four two-input TTL AND gates.

1

74LS32 quad OR gate (U9)

Integrated circuit containing four two-input TTL OR gates.

1

74LS32 quad OR gate (U10)

Integrated circuit containing four two-input TTL OR gates.

1

74LS32 quad OR gate (U11)

Integrated circuit containing four two-input TTL OR gates.

1

74LS32 quad OR gate (U12)

Integrated circuit containing four two-input TTL OR gates.

1

74LS32 quad OR gate (U13)

Integrated circuit containing four two-input TTL OR gates.

1

DIP switch, 4 positions

Four small switches that select the binary inputs A through D.

1

10-pin common-cathode 7-segment display

A one-digit seven-segment display with two common cathodes and a decimal point.

1

220 Ω pull-down resistor for A

220 Ω

A resistor that holds input A at zero when its switch is open.

1

220 Ω pull-down resistor for B

220 Ω

A resistor that holds input B at zero when its switch is open.

1

220 Ω pull-down resistor for C

220 Ω

A resistor that holds input C at zero when its switch is open.

1

220 Ω pull-down resistor for D

220 Ω

A resistor that holds input D at zero when its switch is open.

1

150 Ω segment resistor a

150 Ω

Current-limiting resistor placed before display segment a.

1

150 Ω segment resistor b

150 Ω

Current-limiting resistor placed before display segment b.

1

150 Ω segment resistor c

150 Ω

Current-limiting resistor placed before display segment c.

1

150 Ω segment resistor d

150 Ω

Current-limiting resistor placed before display segment d.

1

150 Ω segment resistor e

150 Ω

Current-limiting resistor placed before display segment e.

1

150 Ω segment resistor f

150 Ω

Current-limiting resistor placed before display segment f.

1

150 Ω segment resistor g

150 Ω

Current-limiting resistor placed before display segment g.

1

150 Ω decimal-point resistor

150 Ω

Current-limiting resistor placed before the display decimal point.

Assemble it in 5 steps

1. Prepara las dos protoboards

Coloca las 13 cápsulas DIP cruzando la ranura central, con la muesca hacia arriba. Pon U1 a U7 en la primera protoboard y U8 a U13, el DIP y el display en la segunda. La Arduino Uno queda a un lado y no se conecta a ningún cable del circuito.

  • No conectes la Arduino Uno a los rieles TTL ni a las señales: solo está en el proyecto para mostrar los componentes.

2. Cablea la alimentación TTL

Usa una fuente regulada de 5 V. Lleva el pin 14 de U1 a U13 al riel de +5 V y el pin 7 de U1 a U13 al riel GND. Conecta los pines 3 y 8 del display al riel GND.

  • Rojo solo para +5 V y negro solo para GND.
  • Una alimentación invertida puede dañar todos los integrados TTL y el display.

3. Monta las cuatro entradas

Conecta un lado de cada interruptor del DIP a +5 V. El otro lado forma A, B, C y D; conecta cada una a su resistencia de 220 Ω y lleva el otro extremo de cada resistencia a GND. Sigue en el diagrama las redes A, B, C, D y sus inversas nA, nB, nC y nD.

  • Etiqueta los dos extremos de cada cable de señal con el mismo nombre de red.

4. Une las compuertas según el diagrama

Conecta únicamente los pines unidos por las redes P1 a P25 y S1 a S19 del diagrama del proyecto. Usa un color de cable diferente para cada cable físico y marca ambos extremos con la misma etiqueta de red.

  • No cambies los pines de una red aunque dos cables parezcan equivalentes: el proyecto conserva exactamente el netlist indicado.

5. Conecta el display con sus ocho resistencias

Coloca una resistencia de 150 Ω entre cada salida y su pin de display: S15 a la resistencia a y luego pin 7; S11 a b y luego pin 6; S16 a c y luego pin 4; S14 a d y luego pin 2; S8 a e y luego pin 1; S17 a f y luego pin 9; S19 a g y luego pin 10; DP a la resistencia dp y luego pin 5.

  • Comprueba el número de pin impreso o la hoja de datos de tu display antes de alimentarlo: un display de 10 pines no siempre mantiene el mismo orden físico entre fabricantes.

Review all connections

1. Connections between "u1_74ls04" and "Arduino"

Functionu1_74ls04Arduino
power145V
ground7GND
digital2 → 74LS08 quad AND gate (U2) 1EXT
digital2 → 74LS08 quad AND gate (U3) 13EXT
digital2 → 74LS08 quad AND gate (U4) 5EXT
digital2 → 74LS08 quad AND gate (U4) 12EXT
digital4 → 74LS08 quad AND gate (U2) 2EXT
digital4 → 74LS08 quad AND gate (U3) 5EXT
digital4 → 74LS08 quad AND gate (U6) 9EXT
digital8 → 74LS08 quad AND gate (U2) 10EXT
digital8 → 74LS08 quad AND gate (U3) 10EXT
digital8 → 74LS08 quad AND gate (U4) 13EXT
digital8 → 74LS08 quad AND gate (U7) 5EXT
digital8 → 74LS08 quad AND gate (U8) 5EXT
ground11GND
ground13GND
digital6 → 74LS08 quad AND gate (U6) 10EXT

2. Connections between "u2_74ls08" and "Arduino"

Functionu2_74ls08Arduino
power145V
ground7GND
digital3 → 74LS08 quad AND gate (U3) 9EXT
digital3 → 74LS08 quad AND gate (U5) 4EXT
digital3 → 74LS08 quad AND gate (U6) 13EXT
digital3 → 74LS32 quad OR gate (U10) 1EXT
digital6 → 74LS08 quad AND gate (U4) 4EXT
digital6 → 74LS08 quad AND gate (U4) 10EXT
digital6 → 74LS08 quad AND gate (U7) 12EXT
digital6 → 74LS32 quad OR gate (U9) 10EXT
digital8 → 74LS08 quad AND gate (U3) 1EXT
digital8 → 74LS08 quad AND gate (U4) 2EXT
digital8 → 74LS08 quad AND gate (U5) 13EXT
digital8 → 74LS08 quad AND gate (U7) 13EXT
digital11 → 74LS08 quad AND gate (U3) 4EXT
digital11 → 74LS08 quad AND gate (U5) 1EXT

3. Connections between "u3_74ls08" and "Arduino"

Functionu3_74ls08Arduino
power145V
ground7GND
digital3 → 74LS32 quad OR gate (U9) 2EXT
digital6 → 74LS08 quad AND gate (U7) 2EXT
digital6 → 74LS32 quad OR gate (U12) 12EXT
digital8 → 74LS08 quad AND gate (U7) 10EXT
digital8 → 74LS32 quad OR gate (U13) 1EXT
digital11 → 74LS08 quad AND gate (U6) 5EXT
digital2 → 74LS04 hex inverter (U1) 6EXT

4. Connections between "u4_74ls08" and "Arduino"

Functionu4_74ls08Arduino
power145V
ground7GND
digital3 → 74LS32 quad OR gate (U10) 2EXT
digital3 → 74LS32 quad OR gate (U11) 5EXT
digital6 → 74LS32 quad OR gate (U9) 1EXT
digital8 → 74LS32 quad OR gate (U11) 1EXT
digital11 → 74LS32 quad OR gate (U9) 12EXT

5. Connections between "u5_74ls08" and "Arduino"

Functionu5_74ls08Arduino
power145V
ground7GND
digital3 → 74LS32 quad OR gate (U13) 9EXT
digital6 → 74LS32 quad OR gate (U9) 4EXT
digital6 → 74LS32 quad OR gate (U12) 9EXT
digital8 → 74LS32 quad OR gate (U10) 4EXT
digital11 → 74LS32 quad OR gate (U10) 9EXT
digital2 → 74LS04 hex inverter (U1) 6EXT
digital5 → 74LS04 hex inverter (U1) 6EXT
digital10 → 74LS04 hex inverter (U1) 6EXT

6. Connections between "u6_74ls08" and "Arduino"

Functionu6_74ls08Arduino
power145V
ground7GND
ground1GND
ground2GND
digital6 → 74LS32 quad OR gate (U9) 5EXT
digital8 → 74LS08 quad AND gate (U8) 4EXT
digital8 → 74LS32 quad OR gate (U9) 9EXT
digital11 → 74LS32 quad OR gate (U13) 4EXT

7. Connections between "u7_74ls08" and "Arduino"

Functionu7_74ls08Arduino
power145V
ground7GND
digital3 → 74LS32 quad OR gate (U11) 9EXT
digital6 → 74LS32 quad OR gate (U12) 1EXT
digital8 → 74LS32 quad OR gate (U11) 12EXT
digital11 → 74LS32 quad OR gate (U10) 10EXT

8. Connections between "u8_74ls08" and "Arduino"

Functionu8_74ls08Arduino
power145V
ground7GND
ground9GND
ground10GND
ground12GND
ground13GND
digital3 → 74LS32 quad OR gate (U11) 4EXT
digital6 → 150 Ω decimal-point resistor 1EXT

9. Connections between "u9_74ls32" and "Arduino"

Functionu9_74ls32Arduino
power145V
ground7GND
digital3 → 74LS32 quad OR gate (U11) 2EXT
digital3 → 74LS32 quad OR gate (U11) 13EXT
digital6 → 74LS32 quad OR gate (U9) 13EXT
digital8 → 74LS32 quad OR gate (U10) 5EXT
digital8 → 74LS32 quad OR gate (U10) 12EXT
digital11 → 74LS32 quad OR gate (U11) 10EXT
digital11 → 74LS32 quad OR gate (U12) 2EXT

10. Connections between "u10_74ls32" and "Arduino"

Functionu10_74ls32Arduino
power145V
ground7GND
digital3 → 74LS32 quad OR gate (U10) 13EXT
digital6 → 74LS32 quad OR gate (U13) 2EXT
digital8 → 74LS32 quad OR gate (U12) 5EXT
digital11 → 150 Ω segment resistor e 1EXT

11. Connections between "u11_74ls32" and "Arduino"

Functionu11_74ls32Arduino
power145V
ground7GND
digital3 → 74LS32 quad OR gate (U12) 10EXT
digital6 → 74LS32 quad OR gate (U13) 5EXT
digital8 → 150 Ω segment resistor b 1EXT
digital11 → 74LS32 quad OR gate (U12) 4EXT

12. Connections between "u12_74ls32" and "Arduino"

Functionu12_74ls32Arduino
power145V
ground7GND
digital3 → 74LS32 quad OR gate (U12) 13EXT
digital6 → 150 Ω segment resistor d 1EXT
digital8 → 150 Ω segment resistor a 1EXT
digital11 → 150 Ω segment resistor c 1EXT

13. Connections between "u13_74ls32" and "Arduino"

Functionu13_74ls32Arduino
power145V
ground7GND
ground12GND
ground13GND
digital3 → 150 Ω segment resistor f 1EXT
digital6 → 74LS32 quad OR gate (U13) 10EXT
digital8 → 150 Ω segment resistor g 1EXT

14. Connections between "display_7seg_cc" and "Arduino"

Functiondisplay_7seg_ccArduino
ground3GND
ground8GND

15. Connections between "dip_4" and "Arduino"

Functiondip_4Arduino
powerA_5V5V
powerB_5V5V
powerC_5V5V
powerD_5V5V
digitalA → 74LS04 hex inverter (U1) 1EXT
digitalB → 74LS04 hex inverter (U1) 3EXT
digitalC → 74LS04 hex inverter (U1) 5EXT
digitalD → 74LS04 hex inverter (U1) 9EXT
digitalA → 74LS08 quad AND gate (U2) 9EXT
digitalA → 74LS08 quad AND gate (U2) 12EXT
digitalA → 74LS08 quad AND gate (U5) 9EXT
digitalA → 74LS08 quad AND gate (U8) 1EXT
digitalB → 74LS08 quad AND gate (U2) 4EXT
digitalB → 74LS08 quad AND gate (U5) 12EXT
digitalB → 74LS08 quad AND gate (U6) 4EXT
digitalB → 74LS08 quad AND gate (U7) 4EXT
digitalB → 74LS08 quad AND gate (U8) 2EXT
digitalC → 74LS08 quad AND gate (U3) 12EXT
digitalC → 74LS08 quad AND gate (U4) 1EXT
digitalC → 74LS08 quad AND gate (U4) 9EXT
digitalC → 74LS08 quad AND gate (U7) 1EXT
digitalC → 74LS08 quad AND gate (U7) 9EXT
digitalD → 74LS08 quad AND gate (U2) 5EXT
digitalD → 74LS08 quad AND gate (U2) 13EXT
digitalD → 74LS08 quad AND gate (U6) 12EXT

16. Connections between "r_a_pull" and "Arduino"

Functionr_a_pullArduino
ground2GND
digital1 → DIP switch, 4 positions AEXT

17. Connections between "r_b_pull" and "Arduino"

Functionr_b_pullArduino
ground2GND
digital1 → DIP switch, 4 positions BEXT

18. Connections between "r_c_pull" and "Arduino"

Functionr_c_pullArduino
ground2GND
digital1 → DIP switch, 4 positions CEXT

19. Connections between "r_d_pull" and "Arduino"

Functionr_d_pullArduino
ground2GND
digital1 → DIP switch, 4 positions DEXT

20. Connections between "r_seg_a" and "Arduino"

Functionr_seg_aArduino
digital2 → 10-pin common-cathode 7-segment display 7EXT

21. Connections between "r_seg_b" and "Arduino"

Functionr_seg_bArduino
digital2 → 10-pin common-cathode 7-segment display 6EXT

22. Connections between "r_seg_c" and "Arduino"

Functionr_seg_cArduino
digital2 → 10-pin common-cathode 7-segment display 4EXT

23. Connections between "r_seg_d" and "Arduino"

Functionr_seg_dArduino
digital2 → 10-pin common-cathode 7-segment display 2EXT

24. Connections between "r_seg_e" and "Arduino"

Functionr_seg_eArduino
digital2 → 10-pin common-cathode 7-segment display 1EXT

25. Connections between "r_seg_f" and "Arduino"

Functionr_seg_fArduino
digital2 → 10-pin common-cathode 7-segment display 9EXT

26. Connections between "r_seg_g" and "Arduino"

Functionr_seg_gArduino
digital2 → 10-pin common-cathode 7-segment display 10EXT

27. Connections between "r_seg_dp" and "Arduino"

Functionr_seg_dpArduino
digital2 → 10-pin common-cathode 7-segment display 5EXT

Deploy the firmware

// Arduino Uno is included only as an unconnected visual workspace anchor.
// The TTL decoder operates entirely in hardware; no Uno pins are used.
void setup() {
}

void loop() {
  delay(1000);
}

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