555 as an astable multivibrator - Electronic Circuits Projects Diagrams Free

barakorit · 17th June 2008, 07:59 AM

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 · 17th June 2008, 08:00 AM

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 · 17th June 2008, 08:18 AM

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 · 17th June 2008, 08:24 AM

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

rjvh · 17th June 2008, 08:47 AM

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 · 17th June 2008, 08:52 AM

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 · 17th June 2008, 09:03 AM

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 · 17th June 2008, 09:07 AM

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 · 17th June 2008, 11:49 AM

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** · 17th June 2008, 12:03 PM

Quote:

Originally Posted by 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.

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

barakorit · 17th June 2008, 12:41 PM

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

ericgibbs · 17th June 2008, 12:51 PM

Quote:

Originally Posted by barakorit

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 · 17th June 2008, 03:00 PM

I answered this question 5 minutes ago on another website.

barakorit · 18th June 2008, 04:19 AM

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

barakorit · 18th June 2008, 06:38 AM

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.

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17th June 2008, 07:59 AM	(permalink)
barakorit	555 as an astable multivibrator 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?

17th June 2008, 08:00 AM	(permalink)
barakorit	555 as an astable multivibrator 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?

17th June 2008, 08:18 AM	(permalink)
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?

17th June 2008, 08:24 AM	(permalink)
barakorit	Not realy. time interval can be +/-1min and even little more.

17th June 2008, 08:52 AM	(permalink)
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

17th June 2008, 09:03 AM	(permalink)
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.

17th June 2008, 09:07 AM	(permalink)
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

17th June 2008, 11:49 AM	(permalink)
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.

17th June 2008, 12:41 PM	(permalink)
barakorit	I'm not familier with programming. Is it possible with hardware only (IC and some capacitors&resistors)?

17th June 2008, 03:00 PM	(permalink)
audioguru	I answered this question 5 minutes ago on another website. __________________ Uncle $crooge

18th June 2008, 04:19 AM	(permalink)
barakorit	Can you please give me the link to your answer? Thanks.

18th June 2008, 06:38 AM	(permalink)
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.