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Building a circuit to flash an LED for 30 seconds, once every hour Answered

Hi, im trying to build an integrated circuit for a device that will flash an LED for 30 seconds and I want it to flash every hour. I'd prefer not to use a microcontroller if possible and just use integrated circuit components. I've looked at oscillators but found none that have such a small frequency. Any advice?

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Jack A Lopez

6 weeks ago

I suggest using counters. I mean if you look at the CMOS 4000 series, here,

https://en.wikipedia.org/wiki/List_of_4000-series_...

then use Ctrl-F, or whatever the command is for your browser, to find the word "counter" you will find several of them.

I am kind of guessing, the smallest amount of time you want to deal with, is around 1.00000 second, and you can find that in those little modules that drive cheap quartz timed clocks. I mean the kind with hands, and little 2-step stepper motor, that pushes the hands around.

From there, you need to count out 30 one second pulses, for your 30 second interval. Then count out 120 of the 30 second interval, to give an interval 1 hour long.

A minor problem you will likely encounter, is these digital ICs usually count in powers of 2, and you will need some sort of logic to convert these counts in binary, to the multiples of 30, 120, etc, you want for your application.

For example, the binary equivalents of 30d, and 120d, are

11110b = 16+8+4+2 = 30 (as a 5-bit binary number)

1111000b = 64+32+16+8 = 120 (as a 7-bit binary number)

where I am using little "b" to mean binary, and little "d", or blank, to mean decimal.

So a four input AND gate, on just those bits where the 1s occur, can be used to detect when a count of 30d, or 120d, has been reached, respectively, for your 5-bit counter or 7-bit counter.


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Josh_Blackburn

6 weeks ago

If timing precision is important, you'd be hard pressed to avoid microcontrollers or specialized timer ICs. If it isn't critical, you could use a slow running timer that trips once every hour to trigger a second, faster timer that blinks the LED for 30 seconds.
If you simply want the LED to be off for 59.5 minutes, then on for 30 seconds, an so on, then a simply 555 timer would likely work with the right component values. The circuit shown below would work. Setting R1 = 4.39Kohms, R2 = 515Kohms, and C = 10,000uF would yield a pulse about 30 seconds long roughly once an hour.

Schematic-of-IC-555-as-Astable-Multivibrator.jpg
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thedisaster

6 weeks ago

Hi, im trying to build an integrated circuit for a device that will flash an LED for 30 seconds and I want it t whatsapp webo flash every 192.168.0.1hour. I'd prefer not to use a microcontroller if possible and just use integrated circuit components. I've looked at oscillators but found none that have such a small frequency. Any advice?

thankyou!!

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Downunder35m

6 weeks ago

Have a look as simple LED flip-flops or blinkers.
As long as accuracy is not too critical it is as simple as having one capacitor charging for an hour that then activates a seperate flsh circuit for the time the capacitor dicharges.