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Questions tagged [internal-resistance]

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48 views

Voltage dip at source side during heavy loads due to Internal Resistance

In any application, during initial start-up/load step, there is an high current requirement. Due to this high current requirement, there is a dip in that connected voltage rail. I researched on why ...
31 views

Should we include Source and Load Impedance while calculating two port parameters?

While calculating the $Z$, or $Y$ or $h$ parameters of a two port network, should we include the source impedance and load impedance or not? In other words, for finding $Y_{11}$, we short the ...
55 views

18650 pack building - is it better to have similar batch or similar capacity?

I'm gonna build battery packs. I have quite a lot of experience with 18650 Li-ion cells, but there's one thing I still don't know. I will buy CCA 100 new cells from seller (for example LGEBHE21865). ...
47 views

What is the internal resistance of a LiPo battery determined by?

Given DKNguyen's answer to my last question, I wanted to know what determines the internal resistance of a LiPo battery. Does it have something to do with its inside chemistry? Is it just roughly ...
582 views

Contradiction:Maximum Power Transfer and High resistance of load

Whenever we load a circuit, there's a drop from the open circuit voltage $v_{oc}$ due to the internal source resistance or Thevenin's resistance$R_{th}$. So we need to have an $R_{load}$ that ...
44 views

Should series connected battery cells have similar internal resistance and to what degree?

I have some Toshiba SCiB cells that I wish to string in 4s configuration. These are Lithium Titanate (LTO) cells. They have a 20Ah capacity and operate safely between 1.5 V and 2.7 V. The cells were ...
450 views

Difference between analog signal and battery voltage

I want to find out if using an analogue sensor is feasible in my noisy environment by running some signal integrity tests before I buy it. Because I don`t have the sensor yet, I need to simulate its ...
41 views

Battery Bank total internal resistance

Let's assume you have a battery bank not connected to anything and we are dealing with perfect ideal values. You just want to calculate the total battery internal resistance of your battery bank. To ...
173 views

Do rail gun systems require high voltage?

I couldn't justify, as to why most rail-gun examples I found would have high current and high voltage. When the rails & projectile can be designed to have low resistance by varying the volume of ...
103 views

Internal resistance of LDo

I was trying to measure the internal resistance of an LDO that will produce 2.85V. I used a Digital multimeter to do this, but I got a resistance of 810 Ohm and the LDO can support upto 450 mA. Will ...
392 views

Under what circumstances would the large internal input resistance of an actual op amp affect circuit operation?

I was able to find a lot about why the input resistance is high and basically infinite. I understand that the input resistance is high so that it doesn't become a load on the signal. I also know that ...
2k views

Finding the Internal Resistance of an Ammeter using a shunt

There is this lab procedure to determine the internal resistance of an ammeter which differs from the usual process. In this new procedure, we connect a voltage supply in series with a resistor of ...
199 views

Internal Resistances of Capacitors

I have read somewhere on a forum that there are two effective internal resistances of a capacitor in a DC circuit but can't seem to find any further information. From what I read 'parallel resistance' ...
354 views

Can you calculate internal resistance of battery by shorting it?

Can I measure the current of a battery by shorting the circuit and by ohms-law divide the voltage of the battery by the current measured to get internal resistance?
281 views

Measuring the Internal Resistance of an Electrolytic Capacitor

I was wondering if its possible to measure internal resistance of a capacitor from a DC circuit using the below formula and method. $\ V=V_0e^{\frac{-t}{\tau}}$ $\ lnV=-1/\tau\ *t + ln V_0$ ...
230 views

Electrolytic Capacitor Internal Resistance

I'm doing an experiment to investigate the internal resistance of an electrolytic capacitor in a DC circuit. Doing this I am measuring the discharge voltage against time, finding tau and from there ...
179 views

What is the recommended battery chemistry for digital multimeters?

I would like to know if the different internal resistances of different battery chemistry somehow affects the calibration of a digital multi-meter. If so, then what would the optimal battery ...
120 views

Input resistance of a BJT common-emitter amplifer

What's the input resistance of the circuit below? I think it is $R_{in}=R_B || r_\pi$, but I am not sure
734 views

Internal Resistance of a Supercapacitor

I am attempting to replace a wall plug power supply with a supercapacitor. From analysing the behaviour of the wall plug I can see that the current drawn is .25A with 800ms spikes of 1.5A (as ...
1k views

Under what conditions would using a voltmeter be more accurate than an ammeter to measure current?

Suppose you have a simple circuit with a voltage source V1 connected to a resistor R1, like this: simulate this circuit – Schematic created using CircuitLab You could connect an ammeter in ...
1k views

How do I measure internal resistence of voltmeter without ammeter?

I know how to do it with ammeter, but how can I find internal resistence without ammeter?
2k views

Maximum current is drawn from a cell when it is shorted. But, why?

First, I must apologize for the trivial-sounding question. We've only recently started with Current Electricity in class, and our teacher posed this question (well, something similar) to us. For ...
371 views

What might cause a fluctuating resistance of a generator winding?

Before assembly of a machine that contains a three phase generator I check the resistance between the 3 phases of the generator with an ohmmeter. The generator is kept stationary and the temperature ...
1k views

JFET - transconductance, gain(mu) and internal resistance at the drain

Hello guys, here is such assignment: to determine gm, internal resistance at the drain and maximum gain (mu). 1) If Transconductance gm can be found from the formulas and graph. 2) How to determine ...
2k views

Real output resistance of MOSFET

This question is related to MOSFET. NMOSFET's resistance was till now defined in many different ways, for example as: or which value varies from 1-50k Ohm. And there is also drain-source on-state ...
76 views

Is the series resistance of an analog ammeter the parallel equivalent of shunt resistor and resistance of galvanometer?

An analog ammeter is made by a galvanometer (with certain $i_{max}$ and resistance $r$), in parallel with a shunt resistor $R_s$ that depends upon the max scale chosen. Nevertheless, when an ...
75 views

Constant voltage term in model of diode with internal resistance

Ideal diode equation is $$V(I)=\eta V_T \mathrm{log}(\frac{I}{I_s}+1)$$ Model: simulate this circuit – Schematic created using CircuitLab If the diode has an internal resistance $r$, a more ...
759 views

“Equivalent resistance” of diode as $V/I$ used to evaluate an approximation

Consider the circuit in picture, used to measure the voltage across diode and current flowing through it. simulate this circuit – Schematic created using CircuitLab With this circuit I do ...
2k views

Decrease of internal resistance of a solar cell while increasing the load resistor?

Imagine to model a solar cell as a power supply $V_p$ in series with an internal resistance $R_p$. This solar cell is connected to a variable load resistance $R_{load}$. Suppose that I keep the ...
6k views

Hexagonal resistor circuit (equivalent resistance ) [closed]

I've already find the equivalent resistance between A en B by Star-Triangle transformation , but can someone just explain how can i handle it by Symmetry,asymmetry network analysis ? all the resistor ...
397 views

Impedance of BNC vs output impedance of function generator

I'm a bit confused on output impedance of function generator and coaxial cable impedance. Consider a function generator with output impedance of $50 \Omega$. Suppose that I connect to it a BNC \\$...
2k views

How to calculate internal generator resistance?

What's the formula for calculating generators internal resistance in a circuit with a load? I am given the load resistance and the voltage sources voltage. What's next? simulate this circuit – ...
3k views

Multimeter current measurement: internal resistance or input impedance specification

As the internal resistance (or input impedance) of a multimeter influences the circuit you are measuring, and therefore influences the reliability of you measurement, it would make sense to me to if ...
466 views

Relation between internal resistance and chosen scale on analog/digital voltmeter/ammeter

On Introductory Circuit Analysis of Boylestad I found out the following about the relation of internal resistance of a multimeter with the scale choosen on the instrument. Analog voltmeter: internal ...