CD40106 – An IC with 6 Schmitt-Trigger Inverters

CD40106 pinout

The CD40106 is a super handy IC with six Schmitt Trigger inverter/NOT gates. It contains 6 individual gates that can be used to create oscillators for blinking LEDs, creating sound, and much more.

A Schmitt trigger input means that the threshold voltage for going from a HIGH to a LOW input is different from the threshold for going from LOW to HIGH.

Pin Overview

Pin NamePin #TypeDescription
VDD14PowerSupply Voltage (+3 to +15V)
GND7PowerGround (0V)
A, B, C, D, E, F1, 3, 5, 9, 11, 13InputInputs to the inverters/NOT gates
A, B, C, D, E, F2, 4, 6, 8, 10, 12OutputOutputs from the inverters/NOT gates
Pin overview for the 40106 IC

What is a Schmitt Trigger Inverter?

An inverter, or a NOT gate, is a standard logic gate that inverts whatever is on the input. A 0 (LOW) becomes a 1 (HIGH), and a 1 (HIGH) becomes a 0 (LOW).

The special thing about a Schmitt trigger inverter is that the threshold voltage for going from a HIGH to a LOW input is different from the threshold for going from LOW to HIGH. This makes it really easy to design oscillators by just adding a resistor and a capacitor to the gate.

Simple oscillator circuit with cd40106

How to Use the CD40106 in a Circuit?

To use the CD40106 in a circuit, you need a power supply voltage of 3 to 15V (some versions support up to 20V, so check the datasheet of your version). Connect the power supply to the VDD and GND pins of the chip.

You can now use any of the six inverters in the chip.

CD40106 Example Circuit – Blinking an LED

In the following circuit example, you’ll build an oscillator that blinks an LED at a rate of about 1 time per second.

Blinking LED circuit diagram

To build this circuit, you’ll need the following components:

  • 9V Battery
  • Schmitt Trigger Inverter (CD40106)
  • Capacitor of 100 µF (C1)
  • 2 x Resistor of 10 kΩ (R1 and R2)
  • An LED

Click here to learn more about how this blinking LED circuit works and how to build it.

Alternatives and Equivalents for CD40106

The 40106 IC is always identified by a prefix and/or a suffix, such as CD40106BE, NTE40106, HEF40106, TC40106BP, MC140106, or HCF40106. This tells you the manufacturer of the chip. Each manufacturer might have slightly different current and voltage ratings, but the functionality and the pins remain the same.

If you can’t find any of these chips in your local electronics store, check out my list of online stores where you can find components and tools for all your electronics projects.

Can’t find the 40106 anywhere? Then try one of the following IC alternatives:

  • 74C14: Pin compatible and supports higher output currents
  • 74xx14: 74HC14, 74LS14, and other chips have the same functionality but lower voltage ratings

40106 Datasheet

Download the PDF datasheet for the IC 40106 here:

Go back to the full overview of the 4000-series integrated circuits