Difference between revisions of "555 Timers"
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The 8-pin 555 timer is one of the most popular [[Integrated Circuits]] (ICs) ever made. | 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. | 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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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. | 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 | + | Most 555 timers are connected to a couple of resistors and capacitors in one of these 4 configurations: |
| − | Monostable - producing a single pulse when triggered | + | * Astable - producing a square wave |
| − | Bistable - a simple memory which can be set and reset | + | * Monostable - producing a single pulse when triggered |
| − | Buffer - an inverting buffer (Schmitt trigger) | + | * Bistable - a simple memory which can be set and reset |
| + | * Buffer - an inverting buffer (Schmitt trigger) | ||
| − | For more details on | + | For more details on variety of circuits that can be built using a 555 timer, see |
* http://www.555-timer-circuits.com/ | * http://www.555-timer-circuits.com/ | ||
* http://en.wikipedia.org/wiki/555_timer_IC | * http://en.wikipedia.org/wiki/555_timer_IC | ||
[[Category:Components]] | [[Category:Components]] | ||
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| + | == Example == | ||
| + | 555 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] | ||
Latest revision as of 06:23, 23 February 2010
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.
Most 555 timers are connected to a couple of resistors and capacitors in one of these 4 configurations:
- 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
Example[edit]
555 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.
