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555 timer ?'s/problem

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browningbuck

New Member
okay so i have no clue why im having an issue, but i built this on my board (see picture)

and it worked exactly like i wanted (its 2 555 in series..i connected 3 pin on first 555 to 8 on second) the design has a delay...then comes on... then turns off , so i am using the idea of a 555 as delay on then the second as a one shot.

now my problem is in the one shot 555 for some reason it worked just fine on the bread board but on the ciruit board it will only wotk if i trigger it...i have to ground out 2 pin on the second 555. i dont want it to do this, i just want the firt 555 to be the trigger. so may ultimate question is why did it wor before and not now, and how to i get it to work as i want?




proof that it did work how i wanted ... i swear!!!
http://s150.photobucket.com/albums/s89/browningbuck/?action=view&current=7d0c7709.pbr
 
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Mike_2545

Super Moderator
Check for solder bridges on the completed board, also if you are using a different power supply than your BB, check to make sure it is of sufficient size.
 

browningbuck

New Member
no everything works, just cant get it to work with out bridging the trigger to turn it on??? and i want it to automaticly just come on, count down, then turn off.

and honestly, the desgn should NOT work with how i had it... so thats another thing to consider
 
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MrDEB

Well-Known Member
you may have destroyed a 555

pin 8 is the Vcc pin.
I think you want to connect the pin 3 of first to pin 2 of the second (trigger pin)
check this web link it may solve your problem
LM555 Timer Circuits
 

tytower

Banned
Some of your wires look pretty close on the BB did they touch ?
 

MrDEB

Well-Known Member
without a trigger??

then you have an astable timer I would think??
what is supposed to get the one shot going if no trigger is used??
 

browningbuck

New Member
yeah i thought so too... but ive set it up three times now with different 555 on the BB and same results? have to triger it to get it going ?
 

MrDEB

Well-Known Member
after re-reading the orginal post

you are powering the second 555 from the output of the first 555.
thats is a form of trigger but going the wrong direction.
When turning on the 555 the timer has to reset itself.
READ THE INFO ON THE LINK I POSTED
it talks about reseting on power up sequence.
IMO I think you smoked one of the 555's
try breading a simple 555 circuit and see if both 555's work, one at a time.
 

browningbuck

New Member
yeah im using pin three to power pin 8 on the second 555.
but forget all that....


if i wanted to do a one shot with out a trigger.. can it be done? i couldnt find anything in the link on it
 
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browningbuck

New Member
and frying the 555 doesnt make sense. if i did it would have been normally open, or closed.... wouldnt work both ways like it did??? its just perplexing the hell out of me
 

MrDEB

Well-Known Member
one shot w/o trigger??

just what are you designing??
if a one shot w/o trigger then what starts the one shot in the first place??
 

browningbuck

New Member
just like the video. there will be a trigger on the first 555, once power is switched on, there is a set delay with a POT, then once first 555 comes on it powers up second 555 for set time. then turns off. so there is a switch at the start of it... but once the switch gives power it should be self controlled
 

browningbuck

New Member
by the way MRDEB i really appriciate you thinking this over... its a weird thing... but it illustrates the versitility of a 555 timer well (i havent divulded i am also using a third 555 once the light is on it osolates)
 
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MrDEB

Well-Known Member
how about starting over

first FULLY explain what you want the circuit to do
then what is actually happening?
you say you don't want to use a trigger??
applying power is basically a trigger.
expain step by step what you want, how many seconds etc. between occurances.
you now mention a 3rd 555????
something about a light??
are photo cells or other light sensing device included
lastly draw a readable schematic. something a person can understand
not some scribbles on note paper. use perhaps expresspcb or ???
your videos show nothing to help with problem
and lastly, don't take suggestions lightly.
test all your 555's. don't assume.
trying to power a 555 off the output of another 555 is not the way to power another ic.
READ the web link I posted, there is lots of useful info to do what I think your trying to do.
 

browningbuck

New Member
MrDEB,

i havent taken one suggestion lightly... the simplest way to form this is:

if power is applied to a one shot 555 can it automaticly turn off?

delay time is doesnt matter due to the use of a Pot on the first 555
the second stage will power the strobing light for 10 seconds
the third just osolates the light while its on

and the reason i know everything is okay, is because the circuit is doing EXACTLY what it is suppose to, i just want it to do something else

 
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MrDEB

Well-Known Member
Is this supposed to be a FLASHBANG?

did you verify ALL the 555's are working?
in the link
LM555 Timer Circuits
it has a schematic to prevent false triggering when power is applied.
You mentioned that you want it to do something elas, not what it is doing?
what is it you want the circuit to do?
looking at your video, it sure looks like a flash bang.
If so I have a circuit as well as pc board design for such a device.
it all fits into an 1 1/4 tube and very bright.
let me in on what you want your circuit to do??
 

MrDEB

Well-Known Member
Several problems with your design

You are not supposed to use the pin 3 to power a second 555.
the current draw is too high as soon as the output of the second 555 goes high.
Your circuit looks wrong .
Couldn't put my finger as to why??
I think your first resistor w/ diode in parelle is wrong being connected to pin 2.
you need to go to the link I posted and there is a schematic that shows a monostable triggering an astable timer (pretty sure thats what your trying to achieve.
here is a schematic for a flashbang that does the same thing as your video except a flashing LED to show its armed.
just add more LED arrays. I recall the unit was to power 60-100 LEDs
 

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