calculations for RC circuit

[love_electronic]

Hi
circuit explanation as follows

whenever the v+ (LP239 of U1:A) exceeds the v- (LP239 of U1:A) the output becomes high (5v).
this output will charge the capacitor and the output of the LP239 U1:B also becomes high as the v+ (LP239 of U1:B) exceeds the v- (LP239 of U1:B).

when the v+ (LP239 of U1:A) lower than the v- (LP239 of U1:A) then the output of both compatators becomes low.

what i want is that the output of the comparator (LP239 of U1:B) take some time to change its output for example 20mS.

for this purpose i added an RC circuit at the v+ of (LP239 of U1:B). Now i want to calculate the values of resistor and capacitors so that i can acheive the delay of 20mS.

R6 will be very small so that the charing will be rapid and diode D1 is installed so that discharging will not occurs from this path.

Need of v- (LP239 of U1:B) is to compare the voltage with RC network and then change the output of comparator.

Can someone tell me the way how to calculate the values?
Hope you guys will understand the function of the circuit.

 

[E-design]

Remember the formula t = R x C? Your time constant which shows that after time (1xt) your voltage would be (0.37 x 5) = 1.84V
This relates to this formula E = 5 x e^-(1xt) = 1.84; You can use this to find the required RC combination to get to 1V trip point after the time you require.
If you work through the calculations, you will find that using a 100nF capacitor and a 120k resistor will give you approx delay of 20mS to the trip point.

 

[love_electronic]

E-design which simulation software you are using?

 

[E-design]

**broken link removed**