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bigkim100

Apr 17, 2013
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Looking for a really simple circuit that when triggered by a 3v pulse, it waits for 3 seconds, triggers for 1 second then turns off waiting for the next pulse.
6 or 9vdc operation.
Thanks in advance for any help.
 

dragon

Oct 31, 2022
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Im an expert at these.
(well I think I could just finish it actually, still beginner!)
:)

I can do it just with batteries caps and resistor timing, but u end up with a washy linear result, it doesnt flick on, just builds up slowly over time.
 

AnalogKid

Jun 10, 2015
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There are several approaches, most of them based on some form of two R-C timers in series.

What power source(s) are available for the circuit?

Where does the input trigger signal come from?

What does the output pulse drive?

ak
 

bigkim100

Apr 17, 2013
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I would use transistors on any out puts to drive relays. I can use any dc power source (6v 9v,etc). The trigger is a logic out of a sensor)
 

Bluejets

Oct 5, 2014
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If you use a 555 there would be no need for transistor on the output as the 555 is quite capable of driving a small relay directly.
The 3v pulse may need to be inverted with a transistor to give the correct trigger.
Simple enough and plenty of how to out there.
Talkingelectronics has books with thousands of circuits.
 

crutschow

May 7, 2021
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Here's the LTspice simulation of one circuit that uses one CD4093 chip to give the delay and one-shot, and one using two 555 chips:
Take you pick--

1669606777244.png


1669610917095.png
 

Bluejets

Oct 5, 2014
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The way I read it, the Op was providing the pulse from another sourceand when this pulse arrived, the magic of the delay was done with the 555.
Then again, word decyphering from some sources is not a specialty of mine.
 

danadak

Feb 19, 2021
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One possibility :



Regards, Dana.
 

bigkim100

Apr 17, 2013
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Im sorry, I dont understand the 4093 circuit, I only see 1 output to the relay, is there a second output? I do see the 2 outputs for the double 555 output.
 

danadak

Feb 19, 2021
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What is the accuracy you want for the timing, delays, events ?

Room temperature application or wide environmental temperature operation ?

Do you care about power up / down glitches ?

Is the trigger source mechanical contacts, that would need debouncing to generate
a clean valid trigger signal ?

Typical pushbuttons, toggle switch or relay contacts unbounced signal -

1669645800906.png


This is all you would need for coding in mBlock for the Arduino chip or board -

1669646244417.png

If you need debounce easy to add that.

This is what you would need -

1669647193060.png

Note Sharp part show is a SSR for switching AC loads. Easy to change that to relay or DC SSR.


Regards, Dana.
 
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bigkim100

Apr 17, 2013
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Actua
What is the accuracy you want for the timing, delays, events ?

Room temperature application or wide environmental temperature operation ?

Do you care about power up / down glitches ?

Is the trigger source mechanical contacts, that would need debouncing to generate
a clean valid trigger signal ?

Typical pushbuttons, toggle switch or relay contacts unbounced signal -

View attachment 57096


This is all you would need for coding in mBlock for the Arduino chip or board -

View attachment 57097

If you need debounce easy to add that.

Regards, Dana.
Usally, I only mention these stats (like most Hobbyists) that you mentioned if they are considered important in the design.
ALL of MY designs that I usually request on here are really Loosey-Goosey...to get me into the ballpark, and if I require something a bit more, at least I have the basic building blocks to start with.
Sometimes people like crutschow are nice enough, and skilled enough to provide me with everything I need, and I can just use their design straight up...and thats absolutely GREAT!
I usually dont even indicate voltages, as I will either simply start my design using the voltages that are required by the supplied design, or I tweek it, and change it accordingly.
I dont need pin numbers , etc., as I can look them up myself, and things like standard Pnp/Npn transistors pinouts are pretty much standard.
Simple things like debouncing, switches and stuff like that I will add myself.
Usually, I only deal with 4 supply voltages 3,6,9,12Vdc, like most hobbyists', but of course, I can take any voltage down using Zeners, and Regulators, voltage/switching glitches are dealt with normally, without even thinking of it.
If I miss something, or something that actually effects the original design that I cannot deal with....I will ask for additional help.
I like to kid myself, thinking that I have a bit more basic knowledge than the standard Hobbyist but alas, I often fail in this.
Thank you for your comments. Kim
 
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crutschow

May 7, 2021
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I dont understand the 4093 circuit, I only see 1 output to the relay
Where did you say you needed two outputs?
In your first post you stated "when triggered by a 3v pulse, it waits for 3 seconds, triggers for 1 second".
 

bigkim100

Apr 17, 2013
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Where did you say you needed two outputs?
In your first post you stated "when triggered by a 3v pulse, it waits for 3 seconds, triggers for 1 second".
DUHHH...you are correct, and that is all I need , my mistake
 

danadak

Feb 19, 2021
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Would ballpark timing in the 100's of % be fine ?

Thats what you get with 555 timers over T and V and Bulk cap tolerances.
Datasheet very misleading as it shows its timing with a relatively small cap,
.1 uF, not a bulk electolytic type cap whose intial tolerance can be in the
100's of % tolerance at room T.

But I suppose one can always throw in a pot to adjust for these difficulties.

Even worse with logic gate based timing, where threshold varies dramatically.
Add that to bulk cap tolerance and you have a system that may or not blink in
your lifetime.....:)


Regards, Dana.
 
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