Source: https://mokxi.com/parts/74hc08 Updated: 2026-11-10 Part # 74HC08 quad AND Four AND gates. See every part - 14 pins - 1 setting - In 1 project - In 4 lessons Drawn live by the editor's own code, at the size you see it. At a glance ## The 74HC08 quad AND in brief What it is, and every setting the properties panel gives it. The 74HC08, the chip many kits still list as the 7408, holds four two-input AND gates in a 14-pin DIP on the same pinout as the 74HC00: gate one is pins 1 to 3 (1A, 1B, 1Y), gate two pins 4 to 6, gates three and four sit on pins 8 to 13 with each output first, GND is pin 7 and VCC pin 14. An output goes high only when both inputs are high, and a low on either input pulls it low by itself, even if the other input is floating. From an Arduino Uno, put VCC on 5V and drive the inputs straight from digital pins. From an ESP32 the catch is levels: Mokxi’s 74HC switches at half its supply, so 3.3 volts reads high here, but a real 74HC on 5 volts wants about 3.5 for a guaranteed high. Run the chip from 3.3 volts, or set the model property to 74HCT08, whose inputs switch at 1.4 volts. A 74LS08 reads a floating input as high, as TTL does. In the full adder template it builds the two carry terms a 74HC32 then joins. Family Logic Pins 14 model 74HC08 (or 74HCT08, 74LS08) Pins ## 14 pins Named as the editor names them, so a wire lands where you expect it. ### Input8 - 1A - 1B - 2A - 2B - 3A - 3B - 4A - 4B ### Output4 - 1Y - 2Y - 3Y - 4Y ### Input or output2 - GND - VCC How to use it ## How to use a 74HC08 AND gate in a full adder The 74HC08 has four two-input AND gates: an output is high only when both its inputs are high. In an adder that is the carry rule, since two ones make a carry, so a full adder needs two of them: one for A and B, and one for Cin and the half sum, A xor B. In the circuit here the first AND gate shares its inputs with the 74HC86’s first XOR, the second takes that XOR’s output and Cin, and both outputs run into a 74HC32. Pin 14 goes to 5 V and pin 7 to GND. Set A and B to 1 and 1Y goes high on its own, before the OR passes it on to the carry LED. Part pin Board pin VCC (pin 14) 5 V GND (pin 7) GND 1A, 1B (pins 1, 2) Switches A and B 2A (pin 4) The 74HC86’s A xor B output 2B (pin 5) Switch Cin 1Y, 2Y (pins 3, 6) The 74HC32’s 1A and 1B Tie the inputs of unused gates to GND rather than leaving them floating. To drive the inputs from an ESP32’s 3.3 V pins with the chip on 5 V, set the model to 74HCT08. Hold the button This is the simulator itself, running here. Click anything to open it in the editor. Open this project in the editor Read the full tutorial How it is modeled ## What is true about the 74HC08 quad AND, here In its help article’s own words: what the simulation gets right, and where it stops. ### 74HC08: quad 2-input AND gate The 7408, same package and pinout as the 74HC00, four AND gates instead of four NANDs. A 0 on either input forces Y low. Propagation delay: 9 ns typical. See it in: Full adder. ### Not modeled One typical delay, and nothing around it. Each chip carries a single propagation delay taken from its datasheet's typical column at VCC = 5 V, CL = 15 pF and 25 °C, and uses it for every path through the package. There is no minimum or maximum, no spread between the gates in one chip, no rise or fall time, no output slew and no dependence on supply voltage, load capacitance or temperature, all of which a real 74HC part has, and all of which a datasheet gives ranges for. On the 74HC595 the one figure is the STCP-to-Qn number used for SHCP and MR to Q7S as well, which the datasheet lists a nanosecond or two apart. No setup, hold or pulse-width checks. The 74HC74 and the 74HC595 take a clock edge whenever they see one; nothing here refuses data that changed too close to the edge or a clock pulse that was too narrow, and nothing warns about it. A real part would metastable or simply miss. No supply current, no output current limit and no bus contention damage. An output driving into another output is resolved as two drivers on one net; nothing gets hot. Sequential parts power up cleared rather than random, because a toggle divider fed Unknown never escapes it. See how faithfully a part behaves. From The 74HC logic family, in full. Projects ## See the 74HC08 quad AND in a project One built-in project uses it. It opens in the editor, already wired. Lessons ## Where it turns up in a lesson 4 lessons place it in their own circuits. ### The twelve week course 1 lesson - Week 6: Arithmetic from gates: the full adder ### Learn articles 3 lessons - Digital Electronics on Chromebooks: Labs by Unit - Half Adder and Full Adder: Truth Table to Breadboard - Virtual Electronics Lab for College Classes More parts ## The rest of the bench Every one of these is drawn and simulated the same way. Full-size breadboard A real 0.1 inch grid with the rails and the center channel, 63 columns wide. Jumper wires Drag from any pin or hole to any other. Corners snap, and you can drag them. Power A supply rail at the voltage you choose. Ground The other end of every circuit. LED Lights when current flows. Five colors, and the brightness is what your eye would see. Filament lamp A tungsten bulb in a holder: an inrush when it is switched on cold, tens of milliseconds to warm up, and dim on half its voltage. Resistor Any value you like, with the color bands drawn to match. ESP32-C3-DevKitM-1 A RISC-V board that runs your firmware at 160 MHz on the real memory map. Pushbutton A 12 mm tactile switch. Hold it while the simulation runs. Raspberry Pi Pico The RP2040 board on our own Cortex-M0+ core. Pick a program and press Run. Raspberry Pi Pico W Raspberry Pi Pico W (RP2040). The same board and the same pinout as a Pico, with the CYW43439 on it. The WiFi is simulated (no radio; real internet through the Cloud panel’s switch), and the on-board LED, which hangs off that chip rather than off GP25, is driven through the same path. Everything else is the Pico. Raspberry Pi 4 Model B Raspberry Pi 4 Model B: the 40-pin header, driven by main.py with RPi.GPIO or gpiozero. See every part ## Wire up the 74HC08 quad AND Open the editor and push it into the breadboard. It is free, and it runs on your own machine. Start building free Open the editor