Difference between revisions of "555 Timers"

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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  
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The 8-pin 555 timer is one of the most popular [[Integrated Circuits]] (ICs) ever made.
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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.
  
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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.  
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The 555 timer will operate from a power supply of 4 V (some versions even less) to about 16 V.
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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.
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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:
 
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Low is also known as 'space', or 'logic 0'. If a digital device is said to be 'off', its output is normally 0V.
 
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High is also known as 'mark', or 'logic 1'. If a digital device is said to be 'on', its output is normally Vs.
 
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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
 
Astable - producing a square wave
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Buffer - an inverting buffer (Schmitt trigger)  
 
Buffer - an inverting buffer (Schmitt trigger)  
  
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Original source from [http://www.555-timer-circuits.com/ 555-timer-circuits.com].
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For more details on a variety of circuits that can be built using a 555 timer, see
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* http://www.555-timer-circuits.com/
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* http://en.wikipedia.org/wiki/555_timer_IC
  
 
[[Category:Components]]
 
[[Category:Components]]

Revision as of 16:15, 25 January 2010

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? --russ_hensel 01:46, 18 January 2010 (UTC)


The 8-pin 555 timer is one of the most popular Integrated Circuits (ICs) ever made. 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.

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 a variety of circuits that can be built using a 555 timer, see

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