60 LED Clock Circuit: Build Your Stunning Time Display!

Description

The circuit presented below employs a total of 60 individual LEDs to visually represent the minutes of a clock and 12 LEDs are used to indicate the hours. The power supply and the fundamental timing circuitry are identical to those utilized in the previously detailed 28 LED clock circuit. The minute section of the clock is constructed from eight instances of the 74HCT164 shift registers, cascaded sequentially, enabling a single bit to be repeatedly circulated through the 60 stages, accurately displaying the desired minute of the hour. Only two of the minute shift registers are visually depicted, connected to 16 LEDs. Pin 13 of each register is connected to pin 1 of the subsequent register, spanning seven registers. Pin 6 of the eighth register should be connected back to pin 1 of the initial register via a 47K resistor. Pins 2, 9, 8, 14, and 7 of all eight minute registers (74HC164) are connected in parallel (pin 8 to pin 8, pin 9 to pin 9, and so on). The hour section incorporates two 8-bit shift registers, operating similarly to the minute registers to display one of twelve hours. Pin 9 of all 74HCT164s (hours and minutes) is connected together. For a 50 Hertz operation, the time base section of the circuit can be modified as shown in the lower drawing labeled "50 Hertz LED Clock Time Base". This requires an additional IC, the 74HC30, as it necessitates decoding 7 bits of the counter instead of 4. The two dual-input NAND gates (1/2 74HC00) that are not utilized in the 50 Hertz modification should have their inputs connected to ground.

Upon application of power, a single “1” bit is loaded into the initial stage of both the minutes and hours registers. To achieve this, a momentary low reset signal is sent to all the registers (at pin 9) and also a NAND gate to prevent any clock transitions at pin 8 of the minute registers. Simultaneously, a high level is applied to the data input lines of both the minutes and hours registers at pin 1. A single positive-going clock pulse (at pin 8) is generated at the end of the reset signal, loading a high level into the first stage of the minute register. The rising edge of the first stage output at pin 3 advances the hours (at pin 8), and a single bit is also loaded into the hours register. Power should remain deactivated for approximately 3 seconds or more before reapplying it, allowing the filter and timing capacitors to discharge. A 1K bleeder resistor is used across the 1000uF filter capacitor to facilitate its discharge within roughly 3 seconds. The timing diagram illustrates the power-on sequence where T1 represents the duration power is applied and the onset of the reset signal, T2 denotes the termination of the reset signal, T3 indicates the clock signal used to move a high level into the first register, and T4 represents the end of the data signal. The time delay from T2 to T3 is exaggerated in the drawing and is actually a very short duration, representing only the propagation delay through the inverter and gate.

Two momentary push buttons can be employed for setting the desired time. The button labeled “M” will increment the minutes slowly, while the button labeled “H” will increment the hours much more rapidly, ensuring that the hours are set slowly. The hours should be set initially, followed by the minutes.

Circuit diagram