# Need help understanding triggering and time delay

#### Vman94

Joined Mar 11, 2019
6
My group at school had to design a 3 controller system with time delay, we have 3 LEDs the red LED turns on immediately, Green LED 2 turns on 2 seconds after the red LED turns on, and the yellow LED 3 turns on 3 seconds after the Red LED, the multisim diagram is attached and we confirmed on the breadboard it works, we have two resistors in series and it feeds the negative input of the LM324N, my question is how does voltage divider rule trigger time delay into the LM324N?

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#### crutschow

Joined Mar 14, 2008
28,556
my question is how does voltage divider rule trigger time delay into the LM324N?
If you can write the equations for what determines the time delay for each stage, you can answer that question.
Hint: It involves a charging RC time-constant and the trigger level of each comparator.

#### LesJones

Joined Jan 8, 2017
3,661
I don't understand how you designed it if you don't know the operating principal. Is this a question set by your teacher ?

Les.

#### crutschow

Joined Mar 14, 2008
28,556
My group at school had to design a 3 controller system with time delay
As Les noted, you didn't do a "design" if you don't understand how it works.

#### Dodgydave

Joined Jun 22, 2012
10,139
The Time constant is R x C1 in Seconds. Your first led is set at 3V reference, the second led at 4.5V approx,, The time constant is 0.7RC for approx 50% Supply voltage,,,

Your problem is the charging is not linear!!
https://www.electronics-tutorials.ws/rc/rc_1.html