# Balancing act RLC circuit

#### Maglatron

Jul 12, 2023
1,286
Hi there, I want to make a circuit and have an analogy if the capacitor bank is a bucket, and charge is the water filling the bucket and is acumalating charge, and the resistor is a hole in the bottom of the bucket and the buckets being filled by a tap of intermitant flow and if the hole is big, lots of water will flow but if it's too big then it will empty the bucket faster than it's being filled too small and the flow will do no worthy amount of work. I want a steady flow of DC current and voltage, the bridge rectifier is the tap the charge is the water, the caps are the bucket and additional to that the flow is the current! I want to balance a inductor with cap bank of 16000uf and a power resistor of 20ohm I don't know what the inductor in this system represents! or it's value that it should be!

#### Attachments

• 1702381157856.png
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#### Maglatron

Jul 12, 2023
1,286
looks good to me!! 150watts and 2.75amps, will check actual numbers later today!! ps I wear rubber gloves, had the resistor the wrong way around current was showing negative flipped it 180degree how do I put in a 20watt load??

Last edited:

#### bertus

Moderator
Nov 8, 2019
3,259
Hello,

From page 24 and on there are formulas for the things you do.

Bertus

#### Attachments

• Unit12.pdf
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Jul 12, 2023
1,286
thanks alot !

#### Maglatron

Jul 12, 2023
1,286
so this is the voltage power and current graph with a 20watt load resistor but when I click current of the 20ohm resistor it shifts the voltage on the 20watt load to a corrosponding approximate 8volts when it should still be at around 50

#### Harald Kapp

##### Moderator
Moderator
Nov 17, 2011
13,632
That is not 20 W but 20 Ω.
it shifts the voltage on the 20watt load to a corrosponding approximate 8volts
No, it doesn't. As is shown on top of the graph the blue line is for the current through R2: which is at ~0.4 A (50 V / 135 Ω = 0.37 A).

By the way: please use labels to name the nodes in your schematic. An indication of e.g. V(n002) doesn't tell us anything as we don't know which node is n002.
When you use labels, the relevant nodes can easily be identified, see this example:

#### Maglatron

Jul 12, 2023
1,286
ok please can you tell me how to label the nodes, I've been wodering this for some time, thanks! and also how do I set a 20watt load in LTSpice, it's ok guys I got it a bit, BUT I don't know how to label the current and power

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#### Harald Kapp

##### Moderator
Moderator
Nov 17, 2011
13,632
tell me how to label the nodes
RTFM, it's all in the LTSPICE help.

Or press F4.

#### Maglatron

Jul 12, 2023
1,286
ok sorry dood! I'll give it a good read!

#### Maglatron

Jul 12, 2023
1,286
I read the manual! I still do not know how to set a 20watt load though, any suggestions?

#### Harald Kapp

##### Moderator
Moderator
Nov 17, 2011
13,632
I still do not know how to set a 20watt load though
power is calculated from $P = \frac{V^2}{R}$
which resolves to $R = \frac{V^2}{P}$so with known P and V you can calculate the required R.

#### Maglatron

Jul 12, 2023
1,286
ok that is what I did last time I think you got confused because bothe the power is 20 watts and the resistor is 20ohm so the result is 151!

#### Maglatron

Jul 12, 2023
1,286
(v^2)/P = (55^2)/20 =151ohm so the 20 watt load resistor is approximatly 150ohm

#### Maglatron

Jul 12, 2023
1,286
the 135 comes from me setting voltage to 52v !

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