555 as an astable multivibrator

[barakorit]

Hi guys,
Can I use a 555 component to create a generator which gives square wave of 15min "on" and 15min "off" (duty cycle=50%)?
If not, do you have another option?

 

[barakorit]

Hi guys,
Can I use a 555 component to create a generator which gives square wave of 15min "on" and 15min "off" (duty cycle=50%)?
If not, do you have another idea?

 

[Mikebits]

You can, but you will have really large R and C values. The circuit would drift a lot over temp. Do you care about accuracy?

 

[barakorit]

Not realy. time interval can be +/-1min and even little more.

 

[rjvh]

No the 555 is not realy suitible to run that kind of time cycles

you can use a 4060 to do that job (see atachment)

Robert-Jan

 

[rjvh]

hi barakorit

can you in the future limit a question to one catagory in this forum please

that helps for the clarity of the conversation and forum in general

Robert-Jan

 

[barakorit]

You're right.
I'm sorry for that.

thanks for the scheme.
One more question:
The capacitors value - 100n or 100u, 220n or 220u.

 

[rjvh]

220 nano Farad

with this value in combination with the resistor valeas you will be able to be in your 15 min range

Robert-Jan

 

[barakorit]

Thanks a lot for the previous circuit.
One more question:
Is it possible to generate an asymmetrical square wave with this component
(15min "on" and 30-45min "off", for example)?
If not, maybe another component will do the job.

 

[Nigel Goodwin]

Thanks a lot for the previous circuit.
One more question:
Is it possible to generate an asymmetrical square wave with this component
(15min "on" and 30-45min "off", for example)?
If not, maybe another component will do the job.

A simple PIC and a little programming will allow any timings you require at great accuracy.

 

[barakorit]

I'm not familier with programming.
Is it possible with hardware only (IC and some capacitors&resistors)?

 

[ericgibbs]

I'm not familier with programming.
Is it possible with hardware only (IC and some capacitors&resistors)?

hi,
Add the 'AND' gate to the 'rjvh' circuit.

This will give 15min ON,,, 45min OFF.

By chosing different R/C values and output pins with gating you can get a number of different ON/OFF times.

 

[audioguru]

I answered this question 5 minutes ago on another website.

 

[barakorit]

Can you please give me the link to your answer?
Thanks.

 

[barakorit]

Lighting on LEDs

Hi guys,
I use the 4060 to generate a 16min Off/16min On square wave.
I want the 16min On signal to turn on a green led every 4 min and keep it lighting until the end of the period (of course that there are 4 green leds).
I want the 16min On signal to turn on a red led every 4 min and keep it lighting until the end of the period (of course that there are 4 red leds).
Can it be done?
In addition, if it's possible, I want the last led in each color to start blinking when there are 2min left until the end of the time.
If not, another idea is to cause the last led in each color to blink for it's entire lighting period (approx. 4min).
I would really appreciate any assistance.
Thanks a lot,
Barakorit.

 

[rjvh]

as explaned in the other post from yesterday by eric gibs: if you put aditional AND gates and play with the outputs of the 4060 you will get that

if it comes to the blinking part than a micro processor based circuit will be the most simple and economical solution to do it

it still can be done on the conventional way but you get a much more complex circuitry

Robert-Jan

 

[barakorit]

I'm sorry Robert-Jan, but I don't understand your answer.
I don't know which outputs can function the way I've just explained.
The blinking is another painful problem...

 

[rjvh]

if you have a look on the data sheet of the 4060 than you see it has 10 outputs if you combine some of the outputs by the use of a AND gate than if both inputs are high the output of the AND gate will also be high

so if you have a on pulse from 16 min on 1 output than you need to find another output that is on for 8 min (pin nr 2 if you use pin nr 3 for the 16 min out)

if you put both out puts in an AND gate than the led will light up only for the time of 8 min of the 16 min

i will draw something for you but it will take some time as i am working at the moment

Robert-Jan

 

[ericgibbs]

hi Barakorit,
Why have you started another post on the same topic.?

Also 'audioguru' has answered this question on another forum,
see his post of yesterday.

 

[barakorit]

Another question:
How did you calculate the value of the capacitors and the resistors in order to achieve 15min on/off square wave.
Is there any formula or equation for that?