Hi all ,
The circuit on the left is a delay off circuit using NE 555 whereas The circuit on the right is delay on circuit. For hobby purpose, lets consider this scenerio. When light is off, the led will turn off after a 3 seconds delay whereas when the light is turn back on, the led will turn on after a 3 seconds delay also. I searched the web for the schematic but cant find it. So, I am deciding to combine the 2 circuit below (delay on & off) to achieve my goal? Is this how we are suppose to do it by combining both ? LT spice file is attached.

Thank you all for reading

 

Here's a single 555 circuit that provides both an ON and OFF delay:
Is that what you want?

 

Wo

Here's a single 555 circuit that provides both an ON and OFF delay:
Is that what you want?

View attachment 264623

Wow sir, I have been searching the web for like 2 hours and couldn't find any. I believe your schematic is the first one to be out in the web haha . Thank you for sharing your knowledge

 

Wow sir, I have been searching the web for like 2 hours and couldn't find any. I believe your schematic is the first one to be out in the web haha . Thank you for sharing your knowledge

You're welcome.
As a hobby, I've generated quite a few variations of 555 circuits, and one did what you wanted, with a little tweaking to get the desired delay times.

555 circuits are relatively easy to understand, once you know the basics of the 555 operation.

 

when the light is turn back on,
What is the Voltage powering the "light" ?
Is the "light" connected to the same Power-Supply as the LED ?
What is the purpose of the Delay ?
Does the Delay need to be adjustable ?, or fixed at exactly 3-seconds to "On", and 3-seconds to "Off" ?
What is the Maximum-Current-Rating of your LED ?
Does the LED need to operate at it's Maximum-Current, or lower, ( to save Battery-Power ).
What is the Forward-Voltage of your LED ?
Is your real-world Power-Supply Regulated at ~10-Volts ? or is it Battery-Powered ?
.
.
.

 

@MrsssSu here is a few references to 555 circuits.

https://www.coursehero.com/file/18175143/50-555Circuits/

 

Here's a single 555 circuit that provides both an ON and OFF delay:
Is that what you want?

View attachment 264624

Hi sir, I have decided to put the circuit to the test on breadboard. However, I do not have a big capacitor (C1) that is 62uF. I only have a 4.7uF maximum. Are there any other parameter that can be adjusted so that it does not utilize too big capactitor to produce the delay Thank you

 

You could try it with the 4.7µF capacitor and larger resistors for R2, R3, R4, & R5 (below), but the high resistor values could give flaky results in a real circuit.

Is it that difficult to buy a larger capacitor?

 

When light is off, the led will turn off after a 3 seconds delay whereas when the light is turn back on, the led will turn on after a 3 seconds delay also.

I don't understand this statement. What do you mean when the "light is OFF"? The V2 pulse, power V1 and/or V3? Is there suppose to be a photocell in the circuit?

 

I'm trying to use this schema to delay the start and off. But I want that the turn on delay to be 10 seconds and the turn off delay 30 seconds.
With this schema it is possible to have a different on and off delay? And if so which resisters/capacitor values I need to change and how can I calculate the new values?

 

Which schematic is that exactly?
And I still don't understand the statement: "when the light is OFF"

 

I'm trying to use this schema to delay the start and off. But I want that the turn on delay to be 10 seconds and the turn off delay 30 seconds.
With this schema it is possible to have a different on and off delay? And if so which resisters/capacitor values I need to change and how can I calculate the new values?

Here's the modified circuit:
R2 adjusts the delay on, and R4 adjusts the delay off.
I'm lazy so I just tweaked the values in the sim, until I got the desired delay times.

 

A simpler method, created by others, I take no credit for that, will be to use a mosfet to do the switching, and for switch on, the switch connects from the positive supply a resistor to the mosfet gate. But there is provided a capacitor between the gate and the supply negative, so that the mosfet goes into conduction slowly, and at some point the relay controlling the load switches ON, and the load is powered. To switch off, the switch connects that gate capacitor to the supply negative thru a different resistor, and the capacitor discharges until the relay releases and the load is switched off.
The benefits are zero standby current and no 555 timer needed.

 

Here's the modified circuit:
R2 adjusts the delay on, and R4 adjusts the delay off.
I'm lazy so I just tweaked the values in the sim, until I got the desired delay times.

View attachment 321394

It took some time for me to have time available but I can give you feedback that it worked fine!
Thanks for the quick reply.