555 timer design question
Favorites|Homepage
Subscriptions | sitemap
HOME > Engineering > 555 timer design question

555 timer design question

[From: ] [author: ] [Date: 11-05-12] [Hit: ]
i know the voltage across the LED is around 0.also the values of the resistors at the output AND how to calculate them.http://www.flickr.please any help would be brilliant :)-Actually one second on and one second off is .5 hertz --- one full cycle in two seconds.......
ok so i posted a question on how to design a 555 timer but accidentally deleted it. I have the values now but i need to know how the person who gave me the values worked them out?
I need to know how to work out the value of all the resistors and the capacitor
if the values aren't clear here they are the first resistor of the 555 timer is 1K ohm, the second is 10K ohm, the capacitor is 140uF the supply is 6V and the 555 timer gives a pulse on for 1 second off for 1 second, i think 1Hz.

i also need the values of the resistors on the output
i know the voltage across the LED is around 0.7V

JUST TO BE CLEAR
i need to know the values of the resistors + capacitor of the 555 timer AND how to work them out
also the values of the resistors at the output AND how to calculate them.

http://www.flickr.com/photos/62049142@N07/5669994814/in/photostream

please any help would be brilliant :)

-
Actually one second on and one second off is .5 hertz --- one full cycle in two seconds.

here is a good tutorial on the 555

http://www.kpsec.freeuk.com/555timer.htm

Tm= .7 *(R1+r2) * C1

Ts= .7 *R2 *C1

for your values we get
Tm=.7 *11000*.00014
Tm=1.078

Ts=.7 *10000 *.00014
Ts=0.98


as to the resisor

LED's need about 3 volts to run
the 555 drops the voltage about .7 volts
LED's usually run .018 amps
if we start with 6 volts then
to get a 2.3 volt drop at .018 ohms
remember it's delta E over amps
R=2.3/.018
R=128
1
keywords: design,555,timer,question,555 timer design question
New
Hot
© 2008-2010 http://www.science-mathematics.com . Program by zplan cms. Theme by wukong .