50-555Circuits.doc

INTRODUCTION
This e-book covers the 555.
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 5)
Another thing you have to be aware of is the voltage on output pin 3. It is about 1-2v LESS THAN rail voltage and does not go to 0v (about 0.7v for 10mA and up to 1900mV for 200mA sinking current).  For instance, to get an output swing of 10v you will need a 12.6v supply. In "electronic terms"  the 555 has very poor sinking and sourcing capabilities.

For photos of nearly every electronic component, see this website: https://www.egr.msu.edu/eceshop/Parts_Inventory/totalinventory.php

You can also search the web for videos showing the 555 in action.
Here are a few:
Making A 555 LED Flasher – Video Tutorial
Three 555 LED Flasher
555 Timer Flasher
Fading LED with 555 timer

Each website has lots more videos and you can see exactly how the circuits work. But there is nothing like building the circuit and that's why you need to re-enforce your knowledge by ACTUAL CONSTRUCTION. 

Learning Electronics is like building a model with Lego bricks. Each "topic" or "subject" or "area" must be covered fully and perfectly, just like a Lego brick is perfect and fits with interference-fit to the next block. When you complete this eBook, you can safely say you will have mastered the 555 - one more "building block" under your belt and in the process learn about DC motors, Stepper motors, servos, 4017 chips, LEDs and lots of other things. Any one of these can take you off in a completely different direction.  So, lets start . . . 

Colin Mitchell
TALKING ELECTRONICS.
talking@tpg.com.au

To save space we have not provided lengthy explanations of how any of the circuits work. This has already been covered in TALKING ELECTRONICS Basic Electronics Course, and can be obtained on a CD for $10.00 (posted to anywhere in the world) See Talking Electronics website (http://www.talkingelectronics.com) for more details on the 555 by clicking on the  following four pages:  555-Page 1  555-Page 2  555-Page 3  555-Test
Many of the circuits have been designed by Colin Mitchell:  Music Box,  Reaction Timer Game,  Traffic Lights, TV Remote Control Jammer, 3x3x3 Cube, while others are freely available on the web. But this eBook has brought everything together and covers just about every novel 555 circuit. If you think you know everything about the 555, take the  555-Test and you will be surprised!

SI NOTATION
All the schematics in this eBook have components that are labelled using the System International (SI) notation system. The SI system is an easy way to show values without the need for a decimal point. Sometimes the decimal point is difficult to see and the SI system overcomes this problem and offers a clear advantage.
Resistor values are in ohms (R), and the multipliers are: k for kilo, M for Mega. Capacitance is measured in farads (F) and the sub-multiples are u for micro, n for nano, and p for pico.  Inductors are measured in Henrys (H) and the sub-multiples are mH for milliHenry and uH for microHenry.
A 10 ohm resistor would be written as 10R and a 0.001u capacitor as 1n.
The markings on components are written slightly differently to the way they are shown on a circuit diagram (such as 100p on a circuit and 101 on the capacitor or 10 on a capacitor and 10p on a diagram) and you will have to look on the internet under Basic Electronics to learn about these differences. 

NEW! FROM TALKING ELECTRONICS
A new range of 555 chips have been designed by Talking Electronics to carry out tasks that normally need 2 or more chips.
These chips are designated: TE 555-1, TE555-2 and the first project to use the TE 555-1 is STEPPER MOTOR CONTROLLER TE555-1.
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