Desktop Clock
Circuit Clock
- Overview
- Page Layout
- Mode and Speed Controls
- Click and Explore
- Inside Views and Lessons
- Truth Tables and Karnaugh Maps
- What Is a Truth Table?
- What Is a Circuit?
- How Are Digital Clock Circuits Made?
- What Is BCD?
- What Is Binary?
- What Is a Flip-Flop?
- What Is a D Flip-Flop (DFF)?
- What Is a JK Flip-Flop?
- What Is a T Flip-Flop?
- What Is an SR Latch?
- SR Latch vs SR Edge Triggered
- Ripple Counter vs Synchronous Counter
- How Does a Quartz Crystal Control Timing?
- What Is a Frequency Counter?
- What Is a Seven Segment Display?
- What Is a Clock Divider?
- What Is a BCD to Seven Segment Decoder?
- What Is a MOD-24 Reset?
- Why Use a 1 Hz Tick?
- What Is a K Map?
- How to Solve a K Map
- Who This Is For
Overview
Circuit Clock is an interactive digital clock circuit simulator. It shows how a quartz oscillator, a divider made from flip-flops, BCD counters, and decoder chips work together to drive seven segment displays. Use it to learn digital logic, timing signals, and how a 24 hour clock is built from real circuit blocks.
Page Layout
The top area has the simulation controls. The left panel is the circuit diagram with labeled blocks, wires, and digits. The right panel shows the hardware output, including the live seven segment display, time, BCD values, and carry pulses.
Mode and Speed Controls
Use Mode to switch between free run (the simulated counters advance on their own) and system time (the clock syncs to your real time each second). Use the speed slider to slow down or speed up the simulation, pause or resume, or step one tick at a time. The Advance buttons jump 60 or 3600 ticks. Reset Time sets the clock to 00:00:00, and Reset Mode and Speed returns to defaults.
Click and Explore
Click any major block on the diagram such as power, timing, divider, counters, decoders, or the seven segment displays to open the lesson modal. On large screens, hover over a section to see a quick summary on the right. Inside the modal, use the back button and the section trail at the top to move between sections.
Inside Views and Lessons
Each lesson includes What, Why, and How explanations and an inside view that animates the signals. For counters and decoders, you can switch between digits, select specific bits, and compare MOD-6 or MOD-10 behavior. This helps you trace how carry pulses move from seconds to minutes and hours.
Truth Tables and Karnaugh Maps
The decoder lesson includes BCD tables, seven segment diagrams, truth tables, and Karnaugh maps. You can click to reveal rows and segment lists, then toggle KMap values and answers to see how each segment output is simplified. This is a hands on way to practice logic minimization.
What Is a Truth Table?
A truth table lists every possible input combination for a logic circuit and shows the corresponding outputs. It is the starting point for building or simplifying decoder logic because it makes each segment on or off decision explicit.
What Is a Circuit?
A circuit is a connected path of components that carries power and signals so the system can do work. In digital electronics, circuits use on or off signals to represent numbers and control how those numbers change over time.
How Are Digital Clock Circuits Made?
A digital clock circuit uses a steady timing source, a divider to create a 1 Hz pulse, flip-flops and counters to count seconds, minutes, and hours, and decoders to turn BCD outputs into seven segment signals. A MOD-24 reset ensures the hours wrap after 23:59.
What Is BCD?
BCD stands for Binary Coded Decimal, where each decimal digit is stored as four bits. It makes it easy to connect counters to displays because each digit is stored separately.
What Is Binary?
Binary is a number system that uses only 0 and 1. Digital circuits use it because switches and wires naturally represent off and on states.
What Is a Flip-Flop?
A flip-flop is a memory element that stores a single bit. It changes state when clocked, which makes it the core building block for counters and registers.
What Is a D Flip-Flop (DFF)?
A D flip-flop samples the D input on a clock edge and stores it at Q. It is often used to build counters and shift registers because it updates in a predictable way.
What Is a JK Flip-Flop?
A JK flip-flop has J and K inputs that can set, reset, or toggle the output on a clock edge. It is useful in counters because it can toggle without extra logic.
What Is a T Flip-Flop?
A T flip-flop toggles its output each time it receives a clock pulse. Clock dividers use T flip-flops to cut a fast clock into slower timing signals.
What Is an SR Latch?
An SR latch is a basic memory circuit built from cross coupled gates. It holds a 1 or 0 until the set or reset input changes.
SR Latch vs SR Edge Triggered
An SR latch responds immediately to input changes, while an edge triggered SR flip-flop only updates on a clock edge. Edge triggering prevents glitches in synchronous circuits.
Ripple Counter vs Synchronous Counter
A ripple counter clocks each flip-flop from the previous one, so changes propagate step by step. A synchronous counter clocks all flip-flops together, which reduces timing skew and makes outputs change at the same time.
How Does a Quartz Crystal Control Timing?
A quartz crystal vibrates at a stable frequency when powered. The oscillator circuit counts these vibrations to create precise timing pulses for the clock.
What Is a Frequency Counter?
A frequency counter measures how often a signal repeats in one second. In a clock circuit, it verifies that the oscillator is producing the expected frequency before the divider creates a 1 Hz tick.
What Is a Seven Segment Display?
A seven segment display lights segments labeled a through g to form digits 0-9. Each segment can be on or off, so a decoder decides which segments to light for each digit.
What Is a Clock Divider?
A clock divider reduces a fast timing signal into slower pulses. In digital clocks it turns a high frequency oscillator into a 1 Hz tick for counting seconds.
What Is a BCD to Seven Segment Decoder?
A BCD to seven segment decoder converts a 4 bit BCD digit into the seven on or off signals needed to light the correct segments.
What Is a MOD-24 Reset?
A MOD-24 reset forces the hour counters back to 00 after 23. It keeps the clock in a 24 hour range by clearing the counters when they reach an invalid count.
Why Use a 1 Hz Tick?
A 1 Hz tick advances the counters once per second. It matches real time and makes the seconds, minutes, and hours roll forward at the correct rate.
What Is a K Map?
A K map is a Gray code grid used to simplify boolean expressions by grouping adjacent ones. It helps you minimize logic for each seven segment output without writing long algebraic steps.
How to Solve a K Map
Start from the truth table, place ones for each output that should be on, then group adjacent ones in powers of two. Each group becomes a simplified term, and the final expression is the OR of those terms.
Who This Is For
Circuit Clock is useful for students, teachers, and hobbyists who want a visual guide to digital electronics, logic gates, and clock circuits. It is also a helpful reference for building a seven segment clock, learning BCD decoding, or exploring how real timekeeping circuits are designed.