hysteresis of capacitor voltage

[parth22]

HI ,
I have a RC circuit, I would like to draw a constant current from capacitor. But i want to draw the current when capacitor is charged around 50%.
Is there any way to make a simulation of this? like by setting a some threshold value or other?

 

[parth22]

Hi,

Again: what do you consider as "the final charging" ?
The most basic formula you need to be able to use in electronics is Ohm's law.
And in your case this is the one and only formula you need.

I expect that you to do this on your own.

In post#9 I already did the one calculation for you.

Now the other: for 3A limit on a 40V input the resistance must be higher than 16.7 Ohms.
--> Try to find a resistor with more than 16.7 Ohms but at the same timeless than 2 Ohms.
This is no rocket science. And you really should be able to do this on your own.

And are you aware that your initial question has nothing to do with all this?
And are you aware that we answered your initial question, but you completely ignored our answers?
*********
Take a look back at your thread. Post#1: No information about 3A input current limit, no information about resistor voltage drop.

*****
But we generally don't like to give a short answer like "no, it's impossible".
I wanted to find a solution for your problem. We tried to cooperate with you. We failed in this.

Klaus

Yes, my initial question was regarding to make some kind of hysteresis ,,,that was solved by adding a switch SW.
Although, i agree inrush current limit and voltage drop conditions come in the later part.

BTW i did't get one thing:
Now the other: for 3A limit on a 40V input the resistance must be higher than 16.7 Ohms.
--> Try to find a resistor with more than 16.7 Ohms but at the same timeless than 2 Ohms.
is it realistic case? how can a resistor have two values..

 

[KlausST]

Hi,

is it realistic case? how can a resistor have two values..

No need to have two values. It needs to fulfill two requirements.
1) R > 16.7 Ohms
2) R < 2 Ohms
They are contradicting. Thus you cant find a value

********
If you had those requirements:
1) R < 16.7 Ohms
2) R > 2 Ohms
Then a value could be found. 10 Ohms for example.

Klaus

 

[parth22]

Hi,


No need to have two values. It needs to fulfill two requirements.
1) R > 16.7 Ohms
2) R < 2 Ohms
They are contradicting. Thus you cant find a value

********
If you had those requirements:
1) R < 16.7 Ohms
2) R > 2 Ohms
Then a value could be found. 10 Ohms for example.

Klaus

Excatly, these are contradicting. A resistor can't have two values AT THE SAME TIME. it can be either time variable or temperature variable (NTC).
BTW thanks.
well you took the average value 10 ohm....but that is not working. It's fine.
could you comment on my switching circuit...why it is not working when connecting with R1.

 

[KlausST]

Hi,

could you comment on my switching circuit...why it is not working when connecting with R1.

I don´t know which circuit you mean.
So I had to go through all your posts to find a "switch" and guess it´s "prac2.png"...
since this filename exists twice in your thread with different content I refer to post#19. But there´s no "R1".

"prac3.png" of post#19? the switch is not related to R1...

Regarding LTspice switch:
I never used a switch in LTspice. Thus I did an internet search for you.

LTspice: Voltage Controlled Switches | Analog Devices

LTspice includes a large number of excellent FET models, but sometimes you need to simulate a simple switch that opens and closes at specific times or under certain conditions.To insert and configure a switch in LTspice… Insert the symbol for the voltage-controlled switch in your schematic...

www.analog.com

It takes endless time to find out what you need. I`ve spent enough time now, thus I give others the opportunity to assist you.

Good luck.

Klaus

 

[parth22]

Hi,

I don´t know which circuit you mean.
So I had to go through all your posts to find a "switch" and guess it´s "prac2.png"...
since this filename exists twice in your thread with different content I refer to post#19. But there´s no "R1".

"prac3.png" of post#19? the switch is not related to R1...

Regarding LTspice switch:
I never used a switch in LTspice. Thus I did an internet search for you.

LTspice: Voltage Controlled Switches | Analog Devices

LTspice includes a large number of excellent FET models, but sometimes you need to simulate a simple switch that opens and closes at specific times or under certain conditions.To insert and configure a switch in LTspice… Insert the symbol for the voltage-controlled switch in your schematic...

www.analog.com

It takes endless time to find out what you need. I`ve spent enough time now, thus I give others the opportunity to assist you.

Good luck.

Klaus

OKah thanks.

 

[barry]

Hi,

I don´t know which circuit you mean.
So I had to go through all your posts to find a "switch" and guess it´s "prac2.png"...
since this filename exists twice in your thread with different content I refer to post#19. But there´s no "R1".

"prac3.png" of post#19? the switch is not related to R1...

Regarding LTspice switch:
I never used a switch in LTspice. Thus I did an internet search for you.

LTspice: Voltage Controlled Switches | Analog Devices

LTspice includes a large number of excellent FET models, but sometimes you need to simulate a simple switch that opens and closes at specific times or under certain conditions.To insert and configure a switch in LTspice… Insert the symbol for the voltage-controlled switch in your schematic...

www.analog.com

It takes endless time to find out what you need. I`ve spent enough time now, thus I give others the opportunity to assist you.

Good luck.

Klaus

I doubt we will ever find what OP needs. This is like playing Whac-a-Mole. (Look it up]

 

[FvM]

A straightforward way would be 1 - 3 A current source.

 

[parth22]

I doubt we will ever find what OP needs. This is like playing Whac-a-Mole. (Look it up]

can you help here...why am i not getting 42V here (can be seen in the image).....
while disconnecting of R1 to C2,,,,,will give 42V at C2....
am i wrong somewhere?

 

[barry]

This is just not going to work. Do you know Ohm's law?

If you've got 500 ma flowing out of Q2, and say it's got a beta of 200, then you'll need 2.5mA flowing into the base. 2.5mA will generate 50V across the base resistor of Q2-where's that 50V going to come from?

 

[parth22]

so

This is just not going to work. Do you know Ohm's law?

If you've got 500 ma flowing out of Q2, and say it's got a beta of 200, then you'll need 2.5mA flowing into the base. 2.5mA will generate 50V across the base resistor of Q2-where's that 50V going to come from?

so any solution,,,,where should i change it?

--- Updated Apr 13, 2022 ---

This is just not going to work. Do you know Ohm's law?

If you've got 500 ma flowing out of Q2, and say it's got a beta of 200, then you'll need 2.5mA flowing into the base. 2.5mA will generate 50V across the base resistor of Q2-where's that 50V going to come from?

I think I got it...I have to reduce R7....