CD4017 IC – Decade Counter ( Circuit Diagram )

CD4017 is one of the CMOS (Complementary Metal-Oxide-Semiconductor) integrated circuits (ICs) that functions as a digital counter/divider. This a 5-stage Johnson decade counter, meaning it has 10 decoded outputs (0 through 9) and can be used for applications such as frequency dividers, timers, and sequencing.

Part number: CD4017

Functions: A Decade Counter with Decoded Output

Package information: DIP 16 Pin, SOP 16 Pin type

Manufacturer: Texas Instruments, NXP


CD4017 ic datasheet


CD4017 consists of 10 output pins (Q0 to Q9) and various control pins (10-stage Johnson counter or 4-bit decade counter). This IC is responsible for incrementing or distributing the count depending on the input signal. In general, operation is controlled using a clock input signal and a reset input signal.

Clock input signal is the basic clock signal used in CD4017. On each edge (rising or falling edge) of the clock signal, the counter is incremented and one of the output pins (Q0 to Q9) is activated. The Reset input signal is used to reset the counter to its initial state.


1. Decoded Outputs (Q0 to Q9): There are 10 decoded outputs representing the binary count from 0 to 9. The Q0 output goes high on the first clock pulse and resets to low on the tenth clock pulse.

2. Reset Input (MR): A high signal on the MR (Master Reset) input resets the counter to zero.

3. Supply Voltage: It typically operates with a supply voltage in the range of 3V to 15V.

4. Low Power Consumption: Being a CMOS IC, it has relatively low power consumption.

5. Output Enable (OE): Some variations of the CD4017 have an Output Enable pin, allowing users to disable or enable the outputs.


CD4017 pinout


Mainly used in various digital circuits, especially LED sequences, digital counters, timing and shift registers, dividers, etc. These ICs offer low power consumption and signal stability, making them useful in a variety of digital systems.

Reference site

1. A Decade Counter with Decoded Output (

CD4017 PDF File


2N4401 – NPN Silicon Transistor

Part number : 2N4401

Functions : This is NPN Silicon Epitaxial Planar Transistor.

Package information : TO-82, SOT-23

Manufacturer : Fairchid Semicondcutor, SEMTECH ELECTRONICS

Image :

2N4401 transistor


2N4401 is NPN switching transistor in a TO-92; SOT54 plastic package. PNP complement: 2N4403

A Silicon NPN Epitaxial Planar Transistor is a type of bipolar junction transistor (BJT) made from silicon, a semiconductor material. This transistor is designed for amplifying or switching electronic signals in various electronic circuits.

NPN Configuration:

1. Emitter (N): The heavily doped N-type layer, which is the source of charge carriers (electrons) in the transistor.

2. Base (P): The thin P-type layer, which controls the flow of charge carriers between the emitter and collector.

3. Collector (N): The N-type layer, which collects the charge carriers that pass through the base-emitter junction.


1. High current (max. 600 mA)

2. Low voltage (max. 40 V)

Absolute maximum ratings ( Ta=25°C )


1. Collector to Base Voltage: Vcbo = 60 V

2. Collector to Emitter Voltage: Vceo = 40 V

3. Emitter to Base Voltage: Vebo = 6 V

4. Collector Current: Ic = 600 mA

5. Total Dissipation: Pd = 625 mW

6. Junction Temperature: Tj = 150°C

7. Storage Temperatue: Tsg = -65 ~ +150°C



2N4401 pinout



1. Industrial and consumer switching applications


2N4401 PDF File