555 for timing Turn on 1 minute each 15 minutes

Thread Starter

barg

Joined Dec 23, 2015
55
Hello,

I need a help in finding a circuit that uses 555 to turn on via n-ch mosfet 1 led - To Turn on each 15 minuets for a period of 1 minuet. them off for the rest of remaining 14 minuets and so on all for 24h/7.

Byd, i have found bellow 1 circuit that turn on after 15 minuets but you need to manually turn it off, also it doesn't repeat it self and absent time duration.


Appreciate your assistance.

Thank you
 
Last edited:

djsfantasi

Joined Apr 11, 2010
6,497
555s are NOT the solution for such long time periods. The accuracy is poor and you might have difficulty finding the parts required.

This article isn’t what you’ve asked for, but it may introduce you to a timer circuit for the 4060. if you can put up with a delay of 15 minutes rather that 4, you can choose the RC components so that the chip itself provides your outputs. Otherwise, you can use the chip to count 1 minute intervals and use a 4 bit counter plus some glue logic to get the 14 minute period.
 

Thread Starter

barg

Joined Dec 23, 2015
55
Hi djsfantasi,

Thank you for the reply, actually, i have noticed the 4060 but i don't have it now... regarding accuracy, it can be tolerance of 1 minuet not so accurate just to give a solution now.
 

crutschow

Joined Mar 14, 2008
25,102
Here's an article on the CD4060 which I would recommend using for the 15 minute timer.
It's more stable, takes a much smaller capacitor, and is easier to set for a long delay than a 555.
You omit the circuitry in red so it operates in the free running (repeat) mode, and use a 555 at its output to get the one minute pulse.
Note that since the 555 triggers on the negative slope, the timer output will need to go high and then low to trigger the 555, so the timeout is twice as long as the table shows, thus you would use the 4m to 12m range to get the 15 minute period.
Couple the 555 trigger input to the CD4060 output with a series capacitor and a resistor to the V+ supply so that the 555 triggers just on the signal edge. Otherwise the 555 will keep triggering as long as the trigger signal is low.
 

dl324

Joined Mar 30, 2015
10,912
I need a help in finding a circuit that uses 555 to turn on via n-ch mosfet 1 led - To Turn on each 15 minuets for a period of 1 minuet. them off for the rest of remaining 14 minuets and so on all for 24h/7.
What accuracy do you require? Long delays will require large timing capacitors. Cap leakage and tolerance will affect timing accuracy. Resistor tolerance will also affect timing, but 1% values are readily available. Cap tolerance is going to be 5% at best, -20/+80% worst case.
 

Bernard

Joined Aug 7, 2008
5,555
I like the 4060 but for this I would use 555, 1 M pots., 100uF & 1000uF caps. Checked C bin & found 1000 uF with 5M ohm leakage. Depends on what you have to work with.
 
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