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Working on LEDs with 555 timer
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Working on LEDs with 555 timer

by elizabethjones on Thu Sep 16, 2021 12:25 am

Hi!

I hope everyone is good. My field is engineering and I am working on LED blinking project using 555 timer. Trying to create something like this: https://www.theengineeringprojects.com/ ... -isis.html

So I need some help in designing this circuit. All I want is to design the circuit in such a way that it will extend the off timing of LEDS more than of turning on time. Suppose LEDS start blinking for 10 seconds then it will turn off for 60 sec. Please lend me a hand to make this circuit. For designing such type of circuit tell me the capacitors and resistors equations.

Thanks

elizabethjones
 
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Re: Working on LEDs with 555 timer

by adafruit_support_mike on Sun Sep 19, 2021 3:58 pm

We don't do design on demand.. there are too many students who want someone else to do their homework for them. We can answer questions and point to toward resources, but if it's your project you'll need to do the work.

elizabethjones wrote:Suppose LEDS start blinking for 10 seconds then it will turn off for 60 sec.

That will require three timers: one for the 10-second delay after the circuit is turned on, one to control the LEDs, and one for the 60-second delay before shutting things off.

As a rule of thumb for 555 circuits, capacitors that charge through resistors have a value known as the 'RC time constant' which equals the resistor value multiplied by the capacitor value. For any starting voltage, the voltage across the resistor will be about 1/3 of its original value after one RC time constant. The 555 timer's threshold voltages are at 1/3 and 2/3 of the supply voltage, so it takes about 1 RC time constant for a 555's output to change from one state to the other.

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