555 timing periods.

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wombweller

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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.
 
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?
 
ericgibbs said:
hi,
How accurate are expecting/requiring these 30sec and 1sec timing intervals to be?
Click to expand...

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?
 


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.
 
wombweller said:
Cheers for that Eric.
Click to expand...

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
 
Last edited:
ericgibbs said:
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
Click to expand...


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
 

Attachments

  • UniversalXtalTimebase.gif
    13.5 KB · Views: 176


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

Sorry if you got this reply twice I made a mistake and loged in with my old user name in the last reply.To make this thred consistant I deleted it and signed back in with my new and correct user name.

Any way back to this topic-

Like I said in my last reply Your forward thinking of adding the functionality of the sync button is really good and of course very usful for acuracy.I think this would be best suited with the moded Quartz with the seconds indicator or any bipolar slave with seconds.

Also I will use the optional led section as always good to see somthing flashing intime.

Cant wait to get this built and running as very exitnig for me to see.I will give you the nod if I get stuck.


ericgibbs said:
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.
Click to expand...


Eric is right but thanks for the reply anyway,always good to hear from people.


Kind regards wombweller, nee markelectro
 


Hi,
Did read other post.

A point of interest, if you move the wire from U1/2 to U2/3 over to U2/5 you will get a 60sec pulse.

The LED is OK, but I did add a 'bleeper' sounder to the T1 collector, I found it easier to hear the beep sound every 30sec and compare it with a R/C clock during testing.

The note regarding the +Vin, means if the incoming 1sec Trigger is at TTL levels, then +Vin must be +5V.

If the Trig is 0/+12V, then +Vin must be +12V, so that the U1/13 input can detect the voltage swing. OK?
 
Eric

Would be really nice in the future to have the option to run one or all three pulses if required this way I could have any of the slave types available running at once.I'm thinking along the lines of three outputs. This will be a future project as I think you have done quite enough work already.

Again I quite agree that the bleep would be a useful addition.

The trigger I have not yet decided on how best this will work for me but the voltage I am free to do whatever will work best for the circuit as the turret clock is completely free of any electrics.

Don't know if to add sensors at the bottom of the pendulum swing or leaf/reed contacts at top middle or bottom any will do.Don't know if I am to make a feature of the contacts or make them discrete. My inital thoughts are to make them bold and large to make a feature as is quite a nice clock as well (double three legged gravity single train Pott's of Leeds, if your interested ?). Are there limitations with the circuit?

Anyway 22.55 in the uk so off to bed.

Regards wombweller
 
hi,
I would avoid any 'mechanical' device for getting the pendulum swing as it could upset the swing time.

Have you considered optical emitters/sensors, pendulum swinging thru the light path?

You could duplicate the 4518/4093 logic, the trigger would drive a number of decoders, if you decide you want more timing periods.
 
ericgibbs said:
hi,
I would avoid any 'mechanical' device for getting the pendulum swing as it could upset the swing time.

Have you considered optical emitters/sensors, pendulum swinging through the light path?.
Click to expand...

Hello Eric
I have considered optical as is a sound solution but I am also thinking along the lines of many already established methods used in many master clocks.Gent used leaf contacts where the pendulum swings from left to right closing the contact on the way these were placed midway down the pendulums length. (see pic)

Also using a set of contact set at the top of the pendulum with arms coming out closing the contacts on each swing as in GPO. masters.
**broken link removed**

Think would take your advice and would go with optotransistor and LED. to be sure of no interferance.Do you have a little schema to add on to the timing circuit? unless you have any other better solutions.



ericgibbs said:
You could duplicate the 4518/4093 logic, the trigger would drive a number of decoders, if you decide you want more timing periods.
Click to expand...


Ha! so simply build more of the same circuits but modify accordingly???


Will goto Maplins tomorrow and purchase some parts.

Regards wombweller
 

Attachments

  • gentcontact this what mine should look like.jpg
    62.7 KB · Views: 146
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