Questions tagged [resistance]

A measure of how much a conductor opposes current flowing through it. It can also refer to a part of a circuit, which has a non-negligible resistance value.

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104 views

Multimeter not picking up a resistance

I am making a set of speakers using 34.5 AWG magnet wire, and neodymium magnets to make a voice coil. For my wire gauge and required length I should have ~3 Ω (DC), 4 Ω (AC). The issue is when I ...
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Predictions based on resistance measurements not matching reality?

I'm using my multimeter to measure the resistance of my tongue, and leaving it on there for a full minute it seems to average out at around 1.5 Million Ohms. However, when I put a 9 volt battery on ...
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Resistance with ENC to RJ-45 hookup

I'm wondering since the Tpin+/- and Tpout+/- pins default uses 49.9 ohm resistors. Since the resistor I have that is closest to 49.9 ohms is 47 ohms. Is 47 ohms won't be any problem? Datasheet with ...
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What resistance would I need?

I'm kinda new to PCB design, but here we go: I've created a simple sub-pump water level monitor and it uses a constant 5V from a MOSFET. In the end, it's all monitored by a raspberry pi and I know if ...
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59 views

How to evaluate equivalent insulation resistance of two cables?

My guess was that the equivalent insulation resistance of two cables in parallel is same as the equivalent resistance of two resistances in parallel. But instead it is the sum of the two insulation ...
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46 views

Voltage and amperage requirements for resistance heating of glass

I am planning to introduce electric heating/boosting in my glass melting furnace. The present temperature of the glass is around 1200 deg C and I need to raise it up to 1300 deg C. I am trying to get ...
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251 views

PC fan speed control

I am making a stir plate out of an old PC fan, variable resistor, and DC power supply from this tutorial. I have two power supply's to choose from, their outputs are: PS1 = 12Vdc, 2A PS2 = 12Vdc, ...
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62 views

Difference between horn and power resister?

I have a circuit where my microcontroller is turning off and on a heavy load using a power mosfet (I've also tried it with a mosfet and a relay which yielded the same results). When I use a power ...
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61 views

Input Resistance and Mid-band Gain of a CE-CE Stage Cascade Amplifier

I am trying to calculate the Input Resistance and Mid-band Gain of a CE-CE stage. Here's what I got so far: I am having some doubts regarding my calculations though. Mainly with the input ...
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38 views

R series by terminal A in a potentiometer

I have a question to clarify about potentiometers. Maybe the question is something silly or obvious, but I would like clarification because I'm not so sure about it and I need to be so as not to miss ...
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123 views

Series/parallel combination of resistance/capacitance in an RC circuit (wrt LCR meter readings)

I have this equivalent circuit I am working on. I have to find out individual values of all components in it. I can measure resistance, capacitance and impedance of the whole circuit. I am not sure ...
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170 views

Find potential difference between nodes A and B in circuit below

By KVL and KCL Ix = 4A and Iy=Iz=6A The potential difference between A and B = Va - Vb = 6 +8Ix =38V I don't understand how we calculated the potential difference using KVL and KCL
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Finding the energy over the capacitor in DC

I tried using Thevenin to solve this and found Rth = 3 and Vth = 12 but this is way off the correct energy of the capactor (the energy is 4J).
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246 views

Can a Dependent source be dependent on itself?

I am looking for the Thevenin Resistance here. However, I have no clue what to do with \$i_b\$ and the source dependent on it. This is the entire circuit. \$i_b\$ is the current through the 5\$k\...
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56 views

Ohm's Law in Practise

When the AUX pin of a stereo is connected to my mobile phone's audio female port, I just measured the voltage at the end of this AUX pin(No load is connected) approximately 2mV using a DMM . But when ...
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63 views

Voltage Drop for Power Supply Testing

I recently bought a 10-30 kV DC, 8-10 mA power supply that I am looking to test before its incorporation. However, the retailer advised me that I should place a load on this power supply - as one ...
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141 views

Thermal resistance - Temperature transistor

I have a transistor with Vsupply = 24VDC, VCEO = 45VDC, ICE = 20mA. How to calculate the delta T (rise in temperature) of this transistor. I would like to know what thermal resistance I may have at ...
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80 views

Inductor dc resistance simulations

How can I simulate the dc resistance/R_dc of a spiral inductor? Here's the circuit I have: I simulate the inductor with a dc source and get the series current from a I_probe. Then calculated the dc ...
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66 views

Pulling voltage on a “pull-up” input down to match voltage of voltage output from another device

I have a large lithium (LiFePO4) battery pack composed of 16 cells in series. It is monitored by a BMS (Battery Management System) which is interfaced to a battery charger (Victron Quattro). The BMS ...
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94 views

Equivalent resistance after using superposition method

Hello I am trying to find the Voltage (U in the photo) using superposition method. And the first step is to compute the voltage given by the contribution of the left source of Voltage. Is this ...
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How can I calculate/estimate the resistance of the thin film structured like in the picture (top view)?

let's say the thin film is made of metal with resistivity rho and thickness t. I need to calculate the sheet resistance between point A and B. any reference suggestion is really appreciated.
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55 views

Calculate equivalent resistance of the circuit

I am really confused with the above problem. Each side represents a resistance R. How should I calculate resistance in case of infinite resistances.
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224 views

NMOS Gate RC Filter Values

I am designing a Reverse Polarity Protection circuit for a project by using an n-channel MOSFET. A basic schematic is shown here. I've added an RC filter so that the voltage on the Gate pin changes ...
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297 views

Microcontroller - Measure Resistance in Circuit

I am creating circuit that will control power of heater coil. For controling power I am using Arduino PWM that controls voltage and by Ohm's Law I am calculating desired power. P = V^2 / R Now the ...
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97 views

Moisture Sensor Resistance

I have made a soil moisture sensor by taking two lines of Veroboard and soldering a wire to each line. The theory is that the resistance will change with the moisture - resistance dropping as the ...
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446 views

calculating input resistance of darlington pair (TIP120) from datasheet values

I've tried to find a way to calculate the input resistance of a darlington pair (TIP120), using the values given in the datasheets. https://www.onsemi.com/pub/Collateral/TIP120-D.PDF After Searching ...
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49 views

Detection of condensation on automotive glass

Wondering if anyone has done this or can add to my theory, my idea is to use a microcontroller to measure the resistance of a heated car windscreen using the pre-existing copper conductors to detect ...
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114 views

Need help to analysis & overcome an issue with LM358 OP-AMP

I want to measure the resistance of a coil which its resistance vary in accordance with its temperature coefficient of resistance, the resistance range of the coil vary between 0.12 Ω to 5.00 Ω, at ...
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62 views

How to find current of different parallel components in SR Latch

I am trying to create an SR Latch with two NOR logic gates that lights an LED. I am implementing the gates using 2 transistors and 2 resistors each. Here is the schematic: simulate this circuit &...
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781 views

Choosing resistor and capacitor for active filter

I am new in designing the active filters though I designed Active low, high and bandpass and notch filter successfully (using Opamp, R and C). But these filters are not actually designed by me :-( I ...
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89 views

Average resistance of MOSFET output characteristics

Suppose we calculate resistance at two points in a MOSFET output characteristics, For example: Vgs is at 5v. At Vds=5V Id=10uA and Vds=2.5V Id=9.3uA. To determine the equivalent resistor of the ...
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66 views

NTC Resistance considerations

I'm sure this is a basic question but I am unable to find an answer anywhere online that explains it in a simple way. I am researching NTC sensors and figuring out how to use them. I want to know ...
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185 views

Effective resistance of a cut toroid

How do I find the resistance of a toroid or hollow cylinder that has been cut along a radius, that is, a straight cut from the center to the outer radius? The outer radius of the cylinder is ro and ...
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82 views

How to test if a, in circuit, complementary darling transistor is still functioning properly?

I think a transistor broke down. My knowledge of electronics is not sufficient to solve my issue, so it seems. Hopefully some better educated mind can help me on this. This question is about ...
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474 views

Common Source JFET amplifier input voltage

I want to compare to different formulas which stand for same parameter/value. Here is common source JFET amplifier circuit schematic: Here is the first formula which should apply in general to all ...
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77 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 ...
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104 views

Can a capacitor have high series resistance and low Q and why?

I measured with an LRC meter (Agilent 1731A) a capacitor at frequency \$1kHz\$, finding \$C=109.4 n F\$. Then I tried to measure the resistance and quality factor of the capacitor: here is what I got....
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149 views

Why for a dipole antenna half wave length is optimum size?

For a dipole antenna, half wave length is optimum size. Why is this so? What I understand is that radiation resistance of antenna is around 50 ohms at this size, which matches with the characteristic ...
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63 views

Am I calculating the total resistance of this circuit correctly?

I'm picking up where I left off over a year ago on a signal conditioning circuit for a data acquisition system. The DUT (Device Under Test) is outputting a 1-25vpp 4000Hz square wave signal. The ...
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57 views

How to calculate equivalent resistance in mixed circuit?

I don't understand is this paralel or serie, can somebody help me?
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59 views

Is my wire rated at a high enough current?

I am in the process of planning a speaker build. I am making sure my current wiring is up to the demands of a new system. The amplifier is a CV 1800, which can put out 9.5 amps at 4 ohms in stereo (...
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76 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 ...
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Wattage in US vs AU/EU household appliances

This oven is listed in both the US and Australia. You can see that it's the exact same model (BOV845). Yet if you open the specifications, the only difference is that the US model uses 1800 Watts ...
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i have a question about the analogy between Hydraulic system and Electrical system

In Hydraulic system the Pump out oil "" flow "" , It doesn't out pressure , well what create the pressure is the " restriction " or "" orifice "" or "" resistance "" . In Electrical system , The ...
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Can I calculate the back EMF, motor constants and internal resistance of a DC motor based on these data?

I connected a small motor hub to the gearhead of the motor. Then, I measured the voltage, current and speed of turning using a tachometer. I am not sure if the added weight/inertia due to the 12g hub ...
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129 views

PCB Circuit Design

I have been developing an high gain amplifier based circuit that amplifies the photodiode generated current and is read by an Adruino. I have already developed and tested my results on a general ...
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Resistance tester

I would need to create a simple tester with battery supply that compares resistance of specific wire with reference (approximately 4 ohms) and determines if the wanted resistance is in desired range. ...
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85 views

Value of a resistance

I read in a book that R1 = U/I why is that ? I mean why is does R1 have the same voltage as the source and has the same current I? it was in an exercice to calculate the values of R1 and R2 .
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Calculation of total resistance and total power of a circuit with _different power values_

Two resistors of 10 ohms and 5 ohms are connected in series with the different powers 1W and 2W respectively, then what is the total resistance and total power?