Here's another pic.
I just watched my watch (second hand) so, these are approx, etc
Whole time period is 60 sec, not 50 sec...........
I re-checked my values, they're not too far off......

 

No there is no way that one package can turn itself off not unless it is designed to do that to begin with. You need to add a counter something extra including an lm555,

 

No there is no way that one package can turn itself off not unless it is designed to do that to begin with. You need to add a counter something extra including an lm555,

Seems to be working "as is" .....
Actually, the circuit is self explanatory. Mono is powered on by NO momentary switch, energizing K1, closing contact, applying VCC permanently, till mono times out, releasing K1 and thus cutting power from circuit......
(I think he just read the first couple of posts then replied, not following the thread, probably just trying to up his posts count)

 

Blink- the light just came on, the time constant for the first ,60 sec, 555 as shown , 2.53Meg X 6.8 μF = 16 sec & I thought that was what you were referring to as the 17 sec. I ran into the problem of long first count about 40 years ogo with a 555, do not remember solution but I'll think about it. Not having power during off time complicates it.

 

Pulse shrinker for 10 sec timer. If desired,the long first pulse can be cut to 10 sec by adding a PNP transistor and resistor in parallel to Rt to shorten charging time to 10 sec. & is then effectivley removed for following pulses. PNP is turned on at powerup and conducts untill Cx is charged to 12V, about 3 sec. Rz is adjusted to give 10 sec on cold start.

 

Good morning Bernard.
Today is experiment day, will be trying out your suggestions.
That's what I suspected on the long pulse, initial charge of Ct takes longer, but when status is established, then it works accordingly. If it's not one thing it's another.
Got to get this thing finished, talked to my son last night (wrestling coach) . He's asked me to make him a countdown clock plus double digit home/away score board LED display. I told him sure, at the rate I'm going, should have him one in about a year LOL.
Have a nice day,
Oxbo

 

You could use a simple R/C timer that powers a 555 astable circuit. Use a trimpot to set the timing length on the R/C timer for a 3-cycle repeat for the 555 circuit. How will you be triggering the alarm circuit? PIR?

 

OK Mr Bernard !
Recap for the day' escspades....
Went into the lab this morning (bench on back porch
Cranked up my simulator (breadboard), ran my circuit several times, not a problem.
Then, following your suggestion to remove 60 sec timer Rt and place it on
output (60 sec timer), energizing circuit I found that the timer would never shut off, just kept going, tried both sides of diode, no change, why this is, I have no idea.
Decided to put ckt back and run it again to verify that that exersize was indeed faulty.
I found the timer (60 sec) was way off on it's timing. Spent half the morning substituting components until finally I got it back to wanted parameters (60 seconds).
Now, the first values I had it working good with were Rt=2.52M & cT=6.8UF.
Second time around, after putting Rt on output, and finally getting back to parameters,
Rt=3M, Ct=15uf.
Got that going well, then tried that transistor thing on the 10 sec timer, couldn't get it to work at all.
Removed the transistor setup, went back to re-check ckt, and, once again, timing of 60 sec timer was way off !
Spent the rest of the day substituting components till just a couple hours ago, got it going within the 60 second time limit again. This time the values are, Rt=1.4M & 15Uf.
And just for the heck of it, I ran Rt to output again, still same results, just kept running. Put Rt back to VCC and amazingly, it worked as it previously did.
During all this day, the little 10 sec timer performed flawlessly, still with it's initial 17 sec first pulse.
This thing has just about worn me out. Possibly, it could be speculated that somewhere something wasn't making good contact in the breadboard during the first two failures
but I doubly checked seating of all components constantly, etc....
Because the 10 sec timer has worked flawlesly all day, I suspect that is due to being in "astable" mode.And, for some reason, the power-up mono seemed to have problems.
I believe that I might re-configure it (60 sec) to be an "astable" 60 sec clock and, after it's initial pulse it would trip K1 (relay) anyway and the same results would occure.
Perhaps in astable mode it would be more reliable upon pwr on.
As I've said, the math just doesn't add up as far as the values for Rt and Ct, I wind up guessing till I get it like I want, etc.
OK, that's about it, I am wore out!
Have a nice day
Oxbo

You could use a simple R/C timer that powers a 555 astable circuit. Use a trimpot to set the timing length on the R/C timer for a 3-cycle repeat for the 555 circuit. How will you be triggering the alarm circuit? PIR?

Otaku;
Appreciate the input.
Indeed, I have about come to the conclusion to make the Mono astable.
And your suggestion of using an R/C ckt for the 60 sec is definitely going to be looked into, first thing in the morning.
As I mentioned in the beginning of this thread, I have a little pendulum device whereby a wired weight within would swing and touch the side of the cylinder when rocked (such as someone getting into boat, or, picking up the tongue of the trailer.
However, I have been looking at vibration switches and proxmity switches on the net, they look attractive, never experimented with one though.
One thing is definite, I can't have the siren going off at 2am in the morning because a cat jumped in the boat, that would not make the neighbors very happy, etc....
Oxbo

 

Also Bernard;
In the circuit you supplied for pulse shortening.
Looking at the 4.7K electrolytic cap ??????? (below RZ ).
Is that 4.7uf ???

 

That'a mighty big cap, you'r right 4.7μF give or take. I breadboarded first 555, 50μF & 1 MΩ gave 54 sec. Maybe you have some leaky caps, put some voltage on your stock for a day or so and maybe they will quit drifting, I do the same. 'Trying a 10,000 μF cap, dont think it will make it to expected 3 hrs.

 

Good morning;
Possible leaky caps, these caps are several years old, but not over 10yrs (man, yrs seem to really be passing by these days).
I made a mailbox alerter back then, activates a little piezo gong every 60 sec in the house (hard wired) when mailbox door it opened.
That project went well, no problems, however, it operates with constant pwr being on, mailbox door (proximity magnets) breaks ckt triggering 555, etc
Have tried to duplicate that particular ckt but values don't work out now.
I just don't know what's going on, driving me nuts.
This was supposed to be just a little simple project, is turning into a nightmare, have spent two weeks getting nowhere fast.
About ready to take it down to the river and toss it.........

 

Just some salt for your wounds; S1 needs several ms of closure to latch K1. I found it easy to set Mono without closing relay. Some capacity at battery side of K1 contact to ground helps stabilize things a bit.[ 1-30 μF ? ].

 

Ok, finally solved my problem ! ! !
Recap of the day.
#1 - Tried ckt first think this morning, Mono=75 sec
Burned ckt in for 20 min, Mono= 55 sec
#2 - Substituted 50uf & 1M, 4 attempts, Mono= 3 min, 1.5 min, 1.25 min, 1.25 min
#3 Tried RC ckt, (sec=RC), went from min values all the way to
using 3 caps (2-500uf (+) 1-470uf) in parallel,
used 11 1M resistors (+) 3 10M's in series,
Hooked up "+" side of caps to VCC, resistors from caps to gnd,
Hooked ckt to point between caps and resistors, results= drives the circuit for 1 sec.
For the heck of it, tried the reverse, no workie.
#4 Ran 50uf/1M, Mono= 65 sec
#5 Ran 15uf/1.4M, Mono= 66 sec
#6 Hooked transistor ckt up (2N3906), varied pot=no results.
#7 Tried 50uf/1M Mono= 65 sec.
#8 Trashed Mono !
#9 Hooked up 10 sec timer to run K1
#10 Decided to be happy with one 17 sec burst, have circuit re-set, etc...
See attached Pic.

This is the end of it ! ! ! ! ! ! !
Case closed !!!!!!!!
I'm posting this, then going outside and hooking up my boat, and going fishin ! ! !
THE END !

 

If it is important that the first pulse of a train of pulses is the same period. then it can be speeded up for one pulse by paralleling the timing resistor, Rt, with a switched resistor, or pot. The switch is a PNP transistor with base current controlled by "discharging" a cap. thru a timing resistor ,Rx, with a time constant of about 2 RC. In example RxCx set for 10 sec.The Pot, unlabled, is then adjusted for desired pulse period,9 sec. R pot= 212k for 9 sec.
This is the final POST by me for this project.I'ts been fun.