Editing 555 Timers

'''It is not normally our policy to quote other web pages, we just link to them.  This may be reverted to just a link.  What do other admins think? --[[User:Russ hensel|russ_hensel]] 01:46, 18 January 2010 (UTC)'''


The 8-pin 555 timer is one of the most useful Integrated Circuits (ICs) ever made and it is used in many circuits. It is also one of the cheapest and most-rugged chips on the market costing anywhere from $0.20 to $1.20 depending on the quantity and distributor 

With just a few external components it takes about 10mA (even when the output is not driving a load) and will operate from 4v to about 16-18v which can be used to build many circuits, not all of them involve timing! A popular version is the NE555 and this is suitable in most cases where a '555 timer' is specified. You may have heard of a 556 timer also, this is simply a dual version of the 555. The dual version (556) is housed in a 14-pin package, the two timers (A and B) share the same power supply pins. 

The 555 relies on both analogue and digital electronic techniques to perform its functions, but if we consider its output only, it can be thought of as a digital device. The output can be in one of two states at any time, the first state is the 'low' state, which is the voltage 0V at the '-' (black) connection of your power supply. The second state is the 'high' state, which is the voltage Vs at the '+' (red) connection of your power supply. Vs is commonly 5V when using digital ICs. For convenience, these states are sometimes referred to by other names: 

Low is also known as 'space', or 'logic 0'. If a digital device is said to be 'off', its output is normally 0V.
High is also known as 'mark', or 'logic 1'. If a digital device is said to be 'on', its output is normally Vs. 

The most common types of outputs can be categorized by the following (their names give you a clue as to their functions): 

Astable - producing a square wave
Monostable - producing a single pulse when triggered
Bistable - a simple memory which can be set and reset
Buffer - an inverting buffer (Schmitt trigger) 

Original source from [http://www.555-timer-circuits.com/ 555-timer-circuits.com].

[[Category:Components]]
@@ Line 1: / Line 1: @@
-The 8-pin 555 timer is one of the most popular [[Integrated Circuits]] (ICs) ever made.
+'''It is not normally our policy to quote other web pages, we just link to them.  This may be reverted to just a link.  What do other admins think? --[[User:Russ hensel|russ_hensel]] 01:46, 18 January 2010 (UTC)'''
-It is also one of the cheapest chips on the market, costing anywhere from $0.20 to $1.20 depending on the quantity and distributor.
-The 555 timer will operate from a power supply of 4 V (some versions even less) to about 16 V.
-The 14-pin 556 timer contains two 555 timers in a single package -- the two timers (A and B) share the same power supply pins.
-Most 555 timers are connected to a couple of resistors and capacitors in one of these 4 configurations:
+The 8-pin 555 timer is one of the most useful Integrated Circuits (ICs) ever made and it is used in many circuits. It is also one of the cheapest and most-rugged chips on the market costing anywhere from $0.20 to $1.20 depending on the quantity and distributor
-* Astable - producing a square wave
-* Monostable - producing a single pulse when triggered
-* Bistable - a simple memory which can be set and reset
-* Buffer - an inverting buffer (Schmitt trigger)
-For more details on variety of circuits that can be built using a 555 timer, see
+With just a few external components it takes about 10mA (even when the output is not driving a load) and will operate from 4v to about 16-18v which can be used to build many circuits, not all of them involve timing! A popular version is the NE555 and this is suitable in most cases where a '555 timer' is specified. You may have heard of a 556 timer also, this is simply a dual version of the 555. The dual version (556) is housed in a 14-pin package, the two timers (A and B) share the same power supply pins.
-* http://www.555-timer-circuits.com/
-* http://en.wikipedia.org/wiki/555_timer_IC
-[[Category:Components]]
+The 555 relies on both analogue and digital electronic techniques to perform its functions, but if we consider its output only, it can be thought of as a digital device. The output can be in one of two states at any time, the first state is the 'low' state, which is the voltage 0V at the '-' (black) connection of your power supply. The second state is the 'high' state, which is the voltage Vs at the '+' (red) connection of your power supply. Vs is commonly 5V when using digital ICs. For convenience, these states are sometimes referred to by other names:
+Low is also known as 'space', or 'logic 0'. If a digital device is said to be 'off', its output is normally 0V.
+High is also known as 'mark', or 'logic 1'. If a digital device is said to be 'on', its output is normally Vs.
+The most common types of outputs can be categorized by the following (their names give you a clue as to their functions):
+Astable - producing a square wave
+Monostable - producing a single pulse when triggered
+Bistable - a simple memory which can be set and reset
+Buffer - an inverting buffer (Schmitt trigger)
+Original source from [http://www.555-timer-circuits.com/ 555-timer-circuits.com].
-== Example ==
+[[Category:Components]]
-timer is an analog integrated circuit based on voltage comparison. If on '''pin 2''' there is a voltage which is lower than 1/3 power supply, the output ('''pin 3''') takes the high level. The circuit keeps that condition until the voltage on '''pin 6''' goes over 2/3 power supply.
-'''Pin 7''' is an electronic switch, and we use it on delay applications, to discharge the capacitor.  When the output takes the low level, pin 7 closes to the ground.
-In the following diagram you can see a possible application, based on 555.
-This simple circuit can be utilized to drive a monostable relay, using a single button switch.
-When I press the button IC output (pin3) assumes the high level, but Q1 transistor swithces
-off. So when I release it the relay is energized (now the exchange switch is closed on 5 and 9).
- When I press the button again IC output assumes the low level, but Q3 transistor switches
-on: when I release the button the circuit goes to the start condition.
-*[http://docs.google.com/leaf?id=0B7LPpongh6DzOTZlNjc3MDUtMzYwMy00ODQ2LWFmODItYmJiZTUyN2IzZDRj&hl=it Schematic]
-*[http://sites.google.com/site/plcandcircuitdiagram/home Related resources]
-*[http://www.mykoncept.com Related resources]