Creating a 10 second timer LED circuit for a beginner

[helenaa]

Hi guys

I'm currently working on a university project where i need to create a LED laser light that once turned on will stay on for 10 seconds and i have no idea where to start. Any ideas would be greatly appreciated (the simpler the better)

 

[Mickster]

How to Build a Delay Before Turn Off Circuit with a 555 Timer

In this project,we will show how to build a delay before turn off circuit with a 555 timer.

www.learningaboutelectronics.com

 

[Pommie]

Is it an LED or a laser?

Mike.

 

[alec_t]

If it is a laser, then I trust you are aware of the necessary safety precautions?

 

[helenaa]

Is it an LED or a laser?

Mike.

Hi Mike
Thanks for your reply!
Apologies its an LED circuit i mistyped
I would prefer not to use a 555 timer if possible

 

[helenaa]

If a 555 timer is necessary for a constant output though then so be it

 

[alec_t]

How accurate does the 10 Secs really need to be? That will determine the type of timer required.

 

[helenaa]

How accurate does the 10 Secs really need to be? That will determine the type of timer required.

not too accurate just approximately 10 secs

 

[RadioRon]

For a simple timer, you have a few options.
1) simple RC circuit, that is based on the time constant of a resistor and capacitor charging and discharging.
2) simple RC circuit using 555 timer. This packages the RC approach into one IC and is a bit more convenient.
3) hardware digital timer, based on counting (or dividing) the pulse stream from a simple oscillator circuit. There are ICs for this that make it easy, like the 74HC4060. This can be more accurate and more stable over temperature and time compared to the RC approach.
4) microprocessor. These are probably too complex for your application, but it is fairly easy to design a PIC or AVR microprocessor circuit to form a simple timer. Might sound like overkill, but the smallest processors are close to the cost of a 555 timer chip. This approach is accurate and flexible.