Analog electronics, Hobby, Integrated circuits, Light, Projects

2 projects with LED effect

The two shown projects to make LED effect using the Johnson counter 4017.

Post that shows the operations of 4017 integrated circuit.Click here

4017 cascade

Material list:

  • Printed Circuit Board (PCB).
  • Wires: for LED support and link them to the board.
  • 555.
  • 4017.
  • 1MΩ potentiometer.
  • 74LS00.
  • Resistors: a 220Ω, a 47kΩ and a 1kΩ.
  • Electrolytic capacitors: a 10μF and a 1μF. The voltage limit for both must be at least 16V.
  • LEDs: 9 reds and 8 yellows.

In this project, two 4017 chips are used to control 17 LEDs, with one, can control in maximum 10 LEDs. A 555 astable, whose frequency can be controlled by a potentiometer, makes a clock signal for 4017.

To put in cascade, it’s necessary an additional integrated circuit (IC) with logic doors.

On IC’s datasheet provided by Texas Instruments, it’s shown how to cascade 3 chip to have 25 outputs.

To activate 17 LEDs, only two IC are used and a AND logic door. The second chip’s CE (pin 13) is linked to GND and Q9 is linked to pin 15 (reset) from first IC. The 74LS00 has 4 NAND logic doors. Using one of these as an inverter, it’s possible to obtain an equivalent AND logic.

Source: Circuits DIY.
sequential schematic for LED effect
The circuit’s schematics. When Q9 (pin 11) of first IC is on “HIGH” level, logic gate output releases clock signal to the second 4017. When second chip’s Q9 (pin 11) is on “HIGH” level, it sends the signal to pin 15 (reset) of the first chip. Making it restart the sequence. C2 is a filter capacitor, to avoid power supply noise to interfere on circuit operation.
LED effect sequential 17 LEDs
The completed circuit. LEDs were arranged to form a spiral and are supported by hard wires.

Electrical e-Library logo with LEDs

Material list:

  • PCB.
  • Wires.
  • 555.
  • 4017.
  • 9V battery.
  • Clip for battery.
  • Electrolytic capacitors: a 2.2μF and a 10μF. The limit voltage must be 16V at minimum.
  • Resistors: a 680Ω, a 470Ω, a 10kΩ, a 47kΩ and a 1kΩ.
  • LEDs: 6 yellows and 10 whites.
  • IRF640N.

This circuit’s operation is simpler, only a 555 astable, which generates a clock signal for a 4017, which turns on white LEDs in sequence. On 555’s pin 3, there’s a type N MOSFET that operates as switch to control yellow LEDs. The LEDs were arranged to form Electrical e-Library logo.

The circuit’s schematics. Click on both schematics to zoom it.

Video showing both circuits working.

About Pedro Ney Stroski

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