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.
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.
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.
- 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.
- 555 Timer IC This particulars of this integrated circuit covered on this page make a lot more sense after you study the basic circuits that follow.
- 555 timer bistable mode – Flip flip basic circuit
- 555 timer monostable mode – One shot
- 555 timer astable multivibrator mode – Flashing LEDs
- 555 timer schmitt trigger logic inverter – NOT gate
- 555 timer LDR controlled astable multivibrator mode LED flasher circuit
- 555 timer – Buzzer output – Astable multivibrator mode – Light dependent resistor LDR controlled circuit
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.
- NPN BJT switch circuit – Bipolar Junction Transistor – 2N3904
- PNP BJT switch – Bipolar Junction Transistor – 2N3906
- NPN BJT emitter follower circuit – transferring a voltage minus a diode drop
- PNP BJT emitter follower circuit – Transferring weak signal voltage with a diode voltage shift
- NPN BJT current source – Bipolar Junction Transistor – 2N3904
- PNP BJT current source – Bipolar Junction Transistor – 2N3906
- Schmitt trigger – NPN BJT
- Zener diode component – voltage reference – regulator
Other basic electronics topics:
- Electronic component appearance and schematics – Commonly used through hole versions
- Electronic circuit basics
- Voltage sources for electronics basics
- Multimeter measuring voltage
- Resistor component – Learning electronics resistors
- Light Emitting Diodes – Indicator LEDs
- LED circuit -Lighting a Light Emitting Diode
- Resistor limiting current – Ohms law
- Multimeter measuring current
- Wattage – Electrical Power unit
- Resistors connected in parallel
- Series resistors
- Voltage divider – Setting a fractional voltage
- Resistor color code
- Diode – Rectifier
- Trimpot – Trimmer potentiometer – Voltage divider – Variable resistor
- Capacitor component
- Capacitor RC time constant
- Voltage ramp Demonstrated using a capacitor.
- LM334 three terminal adjustable current source not a common component. I use for an easy current source in many circuits.
- Switch NOT logic gate – digital signal inverter
- Switch OR gate – LED circuit
- Switch AND gate – LED circuit
- Switch based NAND logic gate – LED demonstration circuit