Switch based NAND logic gate – LED demonstration circuit

NAND gates have a high (on) output if at least one input is low (off). If all input are high , then the output is low.

This is the opposite of the AND gate which has a low output unless all inputs are high. NAND stand for Not AND, which means that it is an inverted AND gate.

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Diagram:

You need use a resistor that can have the full supply voltage across it in this circuit. Normally the LED will be in series with the resistor, but when the LED is off, the resistor will be connected directly to both supply rails.

Simple push button switch based NAND logic gate schematic diagram by electronzap electronzapdotcon
Simple push button switch based NAND logic gate schematic diagram by electronzap electronzapdotcon

The schematic symbol for the NAND gate is an AND gate symbol with a dot at the output to indicate a signal inversion.

Ones and zeros used in the truth table, are generally used to indicate high and low inputs and outputs. But you can also use 1 to stand for both a closed mechanical switch and an on LED. Whereas 0 can stand for an open mechanical switch and also for an off LED.

Of course, if you really need logic gates, then you will most likely want to use the integrated circuit versions like the ones in the kit listed below. They are much more energy efficient.



74HC00 kit that is similar to mine, which isn’t available anymore. List of included IC’s is shown in the images.

Video:

Quick push button switch based NAND logc gate electronics circuit by electronzap

  • The NAND logic gate is a universal logic gate (as is the NOR gate). You can combine NAND gates to make any other logic gate.
  • The resistor in this circuit is similar to a pull up resistor.
Next topics:

Transistors will probably be the most challenging components to learn. Understanding them will help you understand all of electronics much better, and help you the most in being creative while designing your own circuits.

Other basic electronics topics: