# Circuit Analysis

#### uppi_777

Joined Feb 26, 2018
36
Could someone explain me about the circuit given below

May i know how does this Circuit functions and the application

Thanks

#### dl324

Joined Mar 30, 2015
14,356
Is this school work?

Is the source AC or DC? What does the green squiggle connect to? Does the black arrow represent ground?

#### Papabravo

Joined Feb 24, 2006
18,161
Could someone explain me about the circuit given below
View attachment 251532

May i know how does this Circuit functions and the application

Thanks
Looks like it charges and discharges the capacitor. Whopee!

#### uppi_777

Joined Feb 26, 2018
36
Could someone explain me about the circuit given below
View attachment 251532

May i know how does this Circuit functions and the application

Thanks
Is this school work?

Is the source AC or DC? What does the green squiggle connect to? Does the black arrow represent ground?
Source AC
green squiggle is Earth cable connection
Black arrow represents Discharge tip

#### dcbingaman

Joined Jun 30, 2021
559
Looks like a possible human body ESD model.

#### uppi_777

Joined Feb 26, 2018
36
Looks like a possible human body ESD model.
May i know how does this circuit function??

#### Papabravo

Joined Feb 24, 2006
18,161
Repeating yourself is not helpful and many people consider it rude. I told you in post #3 how the circuit works, but you were obviously in such a hurry that you blew right past my explanation. In any case here it is again.

The long winded explanation:
1. When the switch is open the high voltage source charges the capacitor up to but not exactly equal to the voltage of the source. The voltage on the capacitor approaches the value of the source asymptotically. If the voltage is high enough there may be some corona or leakage (arcing).
2. When the switch is closed and the tip is at a lower potential than the voltage on the capacitor, the capacitor discharges through the resistor and asymptotically approaches zero volts, but it never actually gets there.
3. Since the discharge resistor is several orders of magnitude smaller than the charging resistor, the capacitor will charge very slowly, and discharge rapidly.
What more do you want to know?

#### dcbingaman

Joined Jun 30, 2021
559
May i know how does this circuit function??
Papabravo explained it? Is there something specific with the description you need help with?

#### dcbingaman

Joined Jun 30, 2021
559
May i know how does this circuit function??
If this represents a HBM (Human Body Model). The KV source is the human body. The 50Mhom resistor represents the human body ability to charge to high voltages via ES build up. The capacitor represents that amount of charged held by the human body. The switch when closed represents an ESD event. Basically, an ESD event is a large discharge from a high voltage capacitor, the capacitor itself representing the human body.

#### dl324

Joined Mar 30, 2015
14,356
Source AC
Cap isn't going to have much voltage with an AC source (average = 0V). It'll be constantly charging and discharging.

#### Papabravo

Joined Feb 24, 2006
18,161
Cap isn't going to have much charge with an AC source. It'll be constantly charging and discharging.
If the switch does close it will short the AC source. Good luck with that if is connected to the generators at Hoover dam. If it does represent the HBM, then the discharge current is relatively insignificant and 5 RC time constants is like 250 ns.

#### Papabravo

Joined Feb 24, 2006
18,161
Cap isn't going to have much voltage with an AC source (average = 0V). It'll be constantly charging and discharging.
In which case it does nothing in particular at all except short the AC source.

#### Kevil

Joined Jun 28, 2020
130
Have a look at the simulation.

#### Attachments

• 1.3 KB Views: 1

#### Papabravo

Joined Feb 24, 2006
18,161
You modeled V1 as a DC source and the TS thinks it is an AC source.
Nice simulation BTW. 5τ≈ 37.5 msec.

#### BobTPH

Joined Jun 5, 2013
4,785
If the source is AC, it is a low pass filter with, basically, a short to ground switched in.

I think that is highly unlikely.

Does anyone else wonder what the rest of the picture shows? Clearly it has been cropped.

Bob

#### Papabravo

Joined Feb 24, 2006
18,161
If the source is AC, it is a low pass filter with, basically, a short to ground switched in.

I think that is highly unlikely.

Does anyone else wonder what the rest of the picture shows? Clearly it has been cropped.

Bob
I guess somebody must think it would be a distraction.