555-timer circuit to turn on light for 1 hour

Thread Starter

rayrivera

Joined Mar 22, 2017
10
Hello folks, I hope you are all doing well. I would like some help finishing this project. The goal is to build a circuit that turns an led light ON for an hour with one tact switch for a button. The project is currently built with a 555 timer and two buttons. The 555 ic pictured needs a min of 4.5v so I will need to find on with a lower min input. It needs to run off of a 3v button cell battery. I am new to electronics but need to get over the hump. Thank you for any help and guidance.
 

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atferrari

Joined Jan 6, 2004
4,473
Hello folks, I hope you are all doing well. I would like some help finishing this project. The goal is to build a circuit that turns an led light ON for an hour with one tact switch for a button. The project is currently built with a 555 timer and two buttons. The 555 ic pictured needs a min of 4.5v so I will need to find on with a lower min input. It needs to run off of a 3v button cell battery. I am new to electronics but need to get over the hump. Thank you for any help and guidance.
Learnt how to properly title a thread and post a schematic or a block diagram at least.
 

OBW0549

Joined Mar 2, 2015
3,566
Instead of a 555, use the CMOS version such as a TLC555; it will operate on 2-15 volts so should work well off a 3V cell.

It's good practice to give your posts a descriptive title that at least gives a hint as to your topic; "First time posting" doesn't tell anybody anything.
 

AnalogKid

Joined Aug 1, 2013
9,494
An hour is a looooong time for an R-C timer like a 555. If you must use it, go with the CMOS version as above. If you can change, consider a CD4060 circuit. This is a combo oscillator and divider chip and is much better for long time periods.

Here is an example from another thread. How bright does your LED have to be?

ak
1-HR-SSR-1.gif
 

Thread Starter

rayrivera

Joined Mar 22, 2017
10
Instead of a 555, use the CMOS version such as a TLC555; it will operate on 2-15 volts so should work well off a 3V cell.

It's good practice to give your posts a descriptive title that at least gives a hint as to your topic; "First time posting" doesn't tell anybody anything.
Thank you for the gentle suggestion about properly naming my post. I will attempt to fix it and name them accordingly in the future.
 

crutschow

Joined Mar 14, 2008
28,204
I agree with AK.
An hour is a long time for a 555 time.
Use the circuit he posted instead.

But the 0.33μF cap across the PB switch can fry the contacts due to the high surge current.
Put a 100Ω resistor in series with the switch to limit the current.
 

Thread Starter

rayrivera

Joined Mar 22, 2017
10
An hour is a looooong time for an R-C timer like a 555. If you must use it, go with the CMOS version as above. If you can change, consider a CD4060 circuit. This is a combo oscillator and divider chip and is much better for long time periods.

Here is an example from another thread. How bright does your LED have to be?

ak
View attachment 172223
Thank you, white color and medium brightness.
 

Thread Starter

rayrivera

Joined Mar 22, 2017
10
Instead of a 555, use the CMOS version such as a TLC555; it will operate on 2-15 volts so should work well off a 3V cell.

It's good practice to give your posts a descriptive title that at least gives a hint as to your topic; "First time posting" doesn't tell anybody anything.
That TLC555 is going to be my next purchase, thank you.
 

Sensacell

Joined Jun 19, 2012
2,919
You will find the "1 Hour" to be totally unstable and unpredictable with a single stage RC timer - like the 555.

Proceed along this path if an "hour" can be anything between 20 and 90 minutes.
If that's not ok, then you will need another design approach.

How precise the timing needs to be is an important design parameter to specify.
 
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