Download book 50 555 Circuits by Talkingelectronics

Download book 50 555 Circuits by Talkingelectronics


The 555 is everywhere and it is one of the cheapest and most-rugged chips on the market.
It comes as a TTL 555 and will operate from 4v to about 16-18v.  It costs from 20 cents (eBay) to $1.20 depending on the quantity and distributor.    The circuitry inside the chip takes about 10mA – even when the output is not driving a load. This means it is not suitable for battery operation if the chip is to be powered ALL THE TIME.
The 555 is also available as a CMOS chip (ICM7555 or ICL7555 or TLC555) and will operate from 2v to 18v and takes  60uA when the circuitry inside the chip is powered. The “7555” costs from 60 cents (eBay) to $2.00
We call the TTL version “555” and the CMOS version “7555.”   This is called ELECTRONICS JARGON.
The 555 comes as a single timer in an 8-pin package or a dual timer (556) in a 14 pin package.
The 7555 comes as a single timer in an 8-pin package or a dual timer (7556) in a 14 pin package.

The 555 and 7555 are called TIMERS or Timer Chips. They contain about 28 transistors and the only extra components you need are called TIMING COMPONENTS. This is an external resistor and capacitor. When a capacitor is connected to a voltage, it takes a period of time to charge. If a resistor is placed in series with the capacitor, the timing will increase. The chip detects the rising and falling voltage on the capacitor. When the voltage on the capacitor is 2/3 of the supply the output goes LOW and when the voltage falls to 1/3, the output goes HIGH.
We can also do other things with the chip such as “freezing” or halting its operation, or allowing it to produce a single HIGH-LOW on the output pin. This is called a “ONE-SHOT” or MONOSTABLE OPERATION.
When the chip produces an output frequency above 1 cycle per second, (1Hz), the circuit is called an OSCILLATOR and  below one cycle per second, it is called a TIMER.
But the chip should not be called  a “555 Timer,” as it has so many applications. That’s why we call it a “555.” (triple ).

Circuits list in the book 555

Active High Trigger

Active Low Trigger

Alarm Sounds (4)

Amplifier using 555

Animated Display

Automatic Curtain Closer

Astable Multivibrator

Bi-Coloured LED

Bike Turning Signal

Bi-Polar LED Driver

Bi-Stable 555

Building the Circuits

Car Tachometer

Clark Zapper

Clicks Uneven

Continuity Tester

Curtain Closer

Dark Detector


Dice to 7-Segment Display

Display – Animated

Driving A Bi-Coloured LED

Driving A Relay

Driving White LEDs

Fading LED

Fastest 555 Oscillator

Flashing Indicators

Flashing Railroad Lights

Flip Flop

Four Alarm Sounds

Function of each 555 pin


H-Bridge with PWM

Headlight Flasher – faulty circuit

Hee Haw Siren

High Frequency 555 Oscillator

How to use the 555


Increasing Output Current

Increasing Output Push-Pull Current

Inverter 12v to 240v

Inside the 555

Kitt Scanner

Knight Rider

Laser Ray Sound


Latch – using transistors

LED Dice

LED Dimmer


Light Controlled Screamer Siren

Light Detector

Lights – Traffic Lights

Low Frequency 555 Oscillator

Machine Gun

Mark-Space Ratio

Memory Cell

Mercury Switch Detector – faulty circuit

Metal Detector

Missing Pulse Detector – faulty circuit

Model Railway Time

Monostable 555

Morse Keyer

Mosquito Repeller

Motor Controller (stepper Motor)

Motor PWM

Multivibrator – Astable

Music Box

Negative Voltage

Normally Closed Trigger

One-Shot 555


Police Lights1,2,3

Police Siren

Powering A Project

Pulse Extender

Pulser – 74c14

PWM Controller

Railroad Lights (flashing)

Railway Time

Rain Alarm

Ramp Generator

Reaction Timer Game

Replacing 556 with two 555’s

Resistor Colour Codes


Schmitt Trigger

Screamer Siren – Light Controlled

Servo Controller

Servo Tester

Simplest 555 Oscillator

Siren 100dB

Square Wave Oscillator

Stepper Motor Controller

Stun Gun

Substituting a 555 – Part 1

Substituting a 555 – Part 2

Switch Debounce


TE555-1 Stepper Motor Controller

Ticking Bomb

Tilt Switch

Touch Switch

Touch ON-OFF

Toy Organ

Traffic Lights

Traffic Lights – 4 way

Transistor Tester

Trigger Timer – 74c14

Turning Signal

TV Remote Control Jammer

Useless Machine

Uneven Clicks

Up/Down Fading LED

Using the 555


Voltage Doubler

Wailing Siren

Zapper (Dr Clark)

Zener Diode Tester

2 Minute Timer – 74c14

3×3×3 Cube

4 Alarm Sounds

4 way Traffic Lights

10 Minute Timer – 74c14

12v to 240v Inverter

100dB Siren

555’s – a list of substitutes

555 Amplifier

555 Kit of Components

555 Pinout

555 Mistakes (No-No’s)

555 on 24v

555 VCO

556 Dual Timer

Download 555 Circuits

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