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Timer-555 Project Page 1

This Website is Created and Maintained by chris--at--OUPower--dot--com (Fix the address for it to work!)
This Project was last updated on: September 25, 2006 10:37am v7.01

WARNING! Many, if not all of the projects described within these pages, contain dangerous and potentially fatal consequences if you do not exercise proper precautions and follow standard safety procedures. The owner of this site takes no responsibility for injury sustained by anyone attempting to duplicate or utilize any of the information on this site. The information here is strictly for Educational Purposes! -USE AT YOUR OWN RISK!

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555 Pinout

1. Ground. Connect this to ground. Remember to connect all grounds in a circuit together.
2. Trigger. A short low (less than 1/3 Vcc) pulse on the trigger starts the timer. By connecting this to ground we "turn on" the 555 timer.
3. Output. During a timing interval, the output stays at +VCC. Can source up to 200ma.
4. Reset. Forces pin 3 low if pulled to ground.
5. Control. Can be used to adjust threshold trigger voltage. Not used in our applications. Connect to ground with a .01uF cap to eliminate supply noise from Vcc.
6. Threshold. When threshold crosses above 2/3 Vcc timing interval ends.
7. Discharge. connects to ground when output goes low. Controls timing.
8. Vcc. Power supply. Typical range 4.5v to 16v.

555 Monostable mode.
1) Does nothing until a low pulse is applied to trigger (pin 2). Low pulse is usually provided by connecting to ground via a switch or transistor.
2) Output goes high for duration set by R1C time constant.
3) R1 should be between 10k and 14m.
4) Timing cap C should be between 100pF and 1000uF.
5) R2 pulls trigger high to prevent false triggering.
6) Uses - One shot timers, switch debouncing.

555 Astable mode
1) No stable state. Output jumps between Vcc and Ground.
2) Output is a square wave
3) Frequency is set by R1, R2 and C

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This Website is Created and Maintained by chris--at--OUPower--dot--com (Fix the address for it to work!)
This Project was last updated on: September 25, 2006 10:37am v7.01

WARNING! Many, if not all of the projects described within these pages, contain dangerous and potentially fatal consequences if you do not exercise proper precautions and follow standard safety procedures. The owner of this site takes no responsibility for injury sustained by anyone attempting to duplicate or utilize any of the information on this site. The information here is strictly for Educational Purposes! -USE AT YOUR OWN RISK!

Click Here to go to my YouTube Channel!!

Click Here to go to our NEW Facebook Discussion Group! This is replacing the old Discussion Board!

Click Here to go to our ARCHIVED Discussion Boards.

Please consider donating to help support this website!