Hello All

I am looking for help on 555 timer circuits.I have searched the net for info and I have learned quite a bit on the way.Unfortunatly I have not quite found what I am looking for.

I want to control a 555 to give out pulses of 1 sec for a 30 sec period. then stop and wait for the next trigger.I am led to believe that I will require two 555's for this purpose.?

The circuit would have to be able to be manipulated for other user impulse periods.I do realise that this can be done via combinations of caps and resistors.

The main question is the longer periods.

Kind regards wombweller

 

Ok here is my guess:

1 555 timer outputs 30sec of charging power to other 555 timer...

Not sure how you'll then wait for another trigger but that will have to be done for trigger of the first 555.

 

Hi,
Look thru this application note:

http://www.doctronics.co.uk/pdf_files/555an.pdf


You require a 555 configued as a monostable, which you trigger giving a 30sec period, during this 30 sec period
the output of the MS enables a 555 configured as a astable giving 1 sec pulses.....

After the 30sec period the MS stops and waits for your next input.

Do you follow this?

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Eric
"Good enough is Perfect"

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May I ask;

(1) What is the input signal?
(2) Is there more than one input signal?
(3) Have you defined all of the different output signal timings?

Mike

 

Hello and thanks to all for supplying info.

I have a few ideas in mind that I want-

A timer circuit of around 4.5v output with 30 1 sec pulses from trigger- so lets say lighting up an LED. 30 times in 1 sec pulses but during the triggered pulses no more triggers will be accepted until the timer as finished pulsing the 30 1 sec ones.

(Trigger- light LED. 30 X'S in 1 sec pulses -trigger) so does the trigger happen on the 1st and 29th ?

Another similar timer that when triggered will count 30 sec's and then pulse (light an LED) then wait for the next trigger.

(Trigger 1 - 2 - 3 - 4 - 5 - and so on - 28 - 29 - light LED. -trigger)
Got to give a 1 sec pulse every 30 sec so I don't know if the next trigger should be on the 29th count or the 30th to give me an LED lit for 1 sec exactly every 30 secs?

Either way the circuit would have to be manipulable so I can get the correct outputs.

Hope I have made this understandable.

Regards wombweller

 

hi,
How accurate are expecting/requiring these 30sec and 1sec timing intervals to be?

__________________
Eric
"Good enough is Perfect"

PIC tutorials:
Gramo's: www.digital-diy.net/
Bill's: www.blueroomelectronics.com/

 

Hi Eric

These pulses are to drive a clock (sorry another clock thing) I have a turret/ tower clock with a 1 sec pendulum that I want to use as a form of master clock.The idea is to use the pendulum to trigger using a beam break circuit.The 555 timer circuit is to drive a common 30 sec pulse slave clock.So the pendulum swinging in 1 sec beats will cause the trigger and then the timer counts the 30 seconds and then pulses the 1 sec pulse to the slave.I want the pendulum to govern the timing trigger so the 555 as to ignore every pass of the pendulum until it is required again.

The 30 1 sec pulses is to drive a 1 sec slave but the circuit has to be alternating polarity too but I will deal with that once I understand the timing.

So to answer the timing as to be accurate as it is driving a slave clock.


Regards wombweller

 

hi,

I would suggest that you drop the 555 approach.

Consider a counter which counts the 1sec pendulum swings, when its counted 30, it outputs a single pulse to the remote clock.
The 1sec pulses will also be available to drive another clock, the alternate 'polarity' would be a signal inversion.

It will be as accurate as the master clock.

Do you follow this idea?

__________________
Eric
"Good enough is Perfect"

PIC tutorials:
Gramo's: www.digital-diy.net/
Bill's: www.blueroomelectronics.com/

 

Hi Eric

Yes I follow what you have suggested but don't know what parts I could exchange the 555 for.I do realize that a PIC. would do but I want to stay clear of that option,You may ask 'why?' well to be honest it's only a preference that I have to use conventional components.

Good idea of using the pendulum to trigger each pulse and then a counter to count each pulse to give out another pulse on 30.

Could you please advise on what parts would do the counting job?

Regards wombweller

 

hi,
I'll post a block diagram tomorrow.

__________________
Eric
"Good enough is Perfect"

PIC tutorials:
Gramo's: www.digital-diy.net/
Bill's: www.blueroomelectronics.com/

 

Cheers for that Eric.

 

hi,

Attached circuit pdf.

Had a prototype build running, all works OK.

If any questions, please ask.

EDIT: Small mistake on two pin numbers,,, refer Err1.gif

Attached Images

Err1.gif (8.4 KB, 25 views)

Attached Files

SECDIV1.pdf (33.4 KB, 20 views)

__________________
Eric
"Good enough is Perfect"

PIC tutorials:
Gramo's: www.digital-diy.net/
Bill's: www.blueroomelectronics.com/

 

Eric

Thanks very much for your efforts.It may take me sometime to get it built and running but I will purchase the parts probably this weekend and then do some tests.

Is there an out put for the 1 sec alternating pulse within the circuit.Not really a problem if not as I can use a simple contact and a c/o relay.Just thought having two outputs.

What is the optional transistor for ?

Will ask more if I don't understand something when I work through your circuit.


Kind Regards wombweller

 

Attached a universal Xtal timebase circuit from Velleman.
With a 3.2768MHz Xtal you have 50, 100 and 400Hz available at the jumpers J1, J2 and J3.
You can of course calculate all other frequencies as well
Using another Xtal can even give you a 1Hz pulse.
I leave the math to you

Attached Images

UniversalXtalTimebase.gif (13.5 KB, 16 views)

 

Hi,
If you havn't figured out the use of the Reset/Sync button, its for when you want to sync the divider when the 'master' clock second hand is at top dead centre. When your master second hand is nearing '0secs' press and hold the Reset button, release when the second hand hits '0'.... OK?

Hi mcs51mc,
The OP is asking for a 30sec divider that driven with 1sec pulses from a master pendulum house clock, not a xtal reference source.

__________________
Eric
"Good enough is Perfect"

PIC tutorials:
Gramo's: www.digital-diy.net/
Bill's: www.blueroomelectronics.com/