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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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Why does this circuit require such an high resistance?

So I'm new to this and this may be a dumb question, but why is there such high resistance in this circuit when the current/voltage of it isn't that high? A 1M Ohm resistor to the collector seems like ...
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117 views

Detecting blast cap removal from C4 [closed]

In many Television shows (such as NCIS (all of them), Criminal Minds, MacGyver, etc.) there is a bomb consisting of electronics and C4 explosive. Mythbusters have determined that a blasting cap is ...
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35 views

LTspice XVII solving Thevenin Resistance basics

Thevenin voltage is a snap, but how do I get R Thevenin?
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1answer
67 views

Hardware specification terminology

I have a hardware specification document of a product attached below. I am able to understand the following parameters: Input voltage - This is defined for the range of input voltage Resolution - ...
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1answer
56 views

How to solve infinite grid with the observing terminals at diagonal of infinite square matrix?

The answer given is 2/3ohm solution is not given but I can expect how they got that answer but can't justify the way.
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1answer
31 views

Will this SR NOR latch based 4 digit lock work? [closed]

I designed this to make a lock that requires pressing the correct buttons in correct order to power the LED. My intend was to make the 1st push button set the first latch and reset the remaining ...
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1answer
73 views

120 Watts and 7.2 Volts, how many Amps?

For a project I need to switch on a simple handheld vacuum cleaner with an Arduino. I am thinking of using a relay or mosfet. I opened the case and a 7.4 V 2200 mAh Li-Ion battery powers the motor, ...
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1answer
42 views

How to calculate current in voltage divider with load?

Say, I have this circuit (please ignore the zeros, and the diode should be some load that draws 10ua): So, V_in be 12V. I would say that D1 gets R2/(R2+R1)*12V as voltage. Then, as I know that it ...
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3k views

Negative Resistance

I am a bit confused about the physical meaning of negative resistance. Mathematically, a component which has negative resistance shows a decreasing voltage across its terminal when the current inside ...
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1answer
41 views

How Does Resistance Affect EMF Measurements?

I have very little electrical engineering knowledge, but am working on a simple Arduino project that detects electromagnetic fields. The original project specifies that three 1M resistors should be ...
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1answer
94 views

Converting between series and parallel circuits

I have an RCL circuit which which is coupled to an RC circuit via a coupling capacitor, \$C_{c}\$. When the system is on resonance, \$\omega = \omega_{0}\$ the impedance of the RCL is purely resistive,...
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64 views

Is it possible that a load can be destroyed if I am disconnecting all other loads in the circuit but one?

I consider myself as a beginner, so please don't be that hard to me. Can I theoreticaly destroy a unfused load if I disconnect all loads but one in the same circuit? In my understanding the current ...
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1answer
76 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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4answers
128 views

Why doesn’t a resistor drop all of the voltage in a series circuit?

Intro: I feel like there is one more thing that I really need to get a grasp of. Let’s say I have a circuit with a 5V battery and a LED that has a 3V forward voltage. Then before the LED is a ...
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2answers
71 views

Why is the current limited to 20mA when there are LED but 8.04 amps without?

NOTE: I HAVE ELECTRON FLOW ON INSTEAD OF CONVENTIONAL FLOW ON PURPOSE So I was making a circuit and it looks like this: As you can see 8.04A are flowing. That is ...
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1answer
26 views

Resistance/Voltage relation in Rheostat?

According to "How Computers Work" (Tenth Edition) by Ron White, he features a graphic of a potentiometer with three terminals on the bottom with the one on the left being for current flowing in and ...
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2answers
65 views

How to remove 50 Hz, 100mV noise? [closed]

I am getting 100 mV noise signal at 50 Hz. I do not know the origin of the noise. What should I need to do to remove it?
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5answers
130 views

Confusion about Ohm's law and electrical power (basics of electrical engineering)..?

I am studying electrical engineering, but I still have some doubts about Ohm's law and electrical power. According to Ohm's law: \$I=\dfrac{V}{R}\$ So that means voltage is proportional to current. ...
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1answer
76 views

Thevenin Voltage and Resistance Problem

Please help me with this problem I have been set. So, I have successfully used Kirchhoff's Voltage law to determine the voltages and currents across each of the resistors in question (R2 and R3). ...
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1answer
45 views

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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1answer
32 views

Conceptual Question About Hemholtz-Thévenin Theorem

I've been taught that for the Hemholtz-Thévenin's method I need to add an independent voltage source with a current flowing and at the same time "turn off" independent sources of voltage and current ...
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1answer
88 views

Resistors in series and parallel conundrum

Three resistors of some resistance (ohms) are put in series and the measured total resistance is 24 ohm. Now, if the same three resistors are connected in parallel to each other and the total ...
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1answer
104 views

Resistance reading on digital multimeter

I'm working my way through a beginners electronics book (to be specific it's 'Starting Electronics' by Keith Brindley). I've got up to the second chapter which introduces resistors and their colour ...
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1answer
128 views

Why do two different multimeters show completely different resistance readings?

I just received a brand new Brymen 869s and I'm concerned it may be broken as it's giving a strange reading. When measuring a 100k 0603 resistor which is soldered into a PCB (forming part of a ...
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1answer
41 views

Ouput resistance of a charger

I want to measure output of a charger (MODEL: GB28-25126) with below picture: When I connect my HIOKI multi-meter (3280-10F) to output of my charger in order to measure the resistance, it shows OF (...
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1answer
82 views

How does a ground node affect this circuits equivalent resistance?

I'm new to circuit analysis and I bumped into this problem that Im not sure how to solve. Originally the exercise had two ground nodes at the same ground level but I saw a thread that said that it ...
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3answers
37 views

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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1answer
31 views

ITS-90 Tempature coefficents for a standard PT100 385 RTD

I'm currently using the ITS-90 formula to convert a resistance of an RTD to a temperature. I got the coefficients from the manufacturers calibration sheet. The problem is I have another probe that I ...
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1answer
64 views

What's the reason for this symmetry argument?

Okay so I've learnt about various methods to find equivalent resistance in circuit. But there's one particular argument which I don't understand and I would be grateful if someone will prove it using ...
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2answers
77 views

How to use a multimeter to test the resistance of my tongue?

I just purchased this cheap-o multimeter: https://www.amazon.com/AstroAI-Digital-Multimeter-Voltage-Tester/dp/B01ISAMUA6/ref=sr_1_1?keywords=astroai+am33d&qid=1551837071&s=gateway&sr=8-1 ...
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3answers
88 views

Chop Saw Inrush Current Limiter?

I have a Dewalt Metal cutting abrasive saw that tends to open a breaker on starting up. It draws 75A on startup tripping the magnetic part of the breaker and opening it. This circuit is only to stop ...
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0answers
43 views

Calculating equivalent resistance using loop analysis with no applied voltage

I have a bridge circuit that I am supposed to find an equivalent resistance between points K and P for using loop analysis. I am aware that a delta Y transformation is the much more direct route, ...
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1answer
66 views

Limiting current of a transformer used for resistance soldering

I'm working on a device capable of soldering wires to tiny components (3mm brass rings). I've used a PSU of a computer to make a resistance soldering device. Using the 5V line and a graphite stick of ...
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0answers
18 views

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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3answers
145 views

Resistor network - how do I reduce this?

How do I find the value of this resistor network. Is the 10 ohm resistor in parallel with the 20 ohm resistor? Is the 16 ohm resistor in parallel with the 5 and 20 ohm resistors in series? I can't ...
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1answer
85 views

Fuel sender - need something to convert ohms to volts?

I need to connect a cars fuel sender(ohms) to a analog input on a GPS tracker (volts) Here's the catch, in our tests most fuel senders we worked with seem to send the data as ohms/resistance However,...
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1answer
54 views

How to power an electric motor

I would like to attempt to assemble an outrunner BLDC motor from scratch. Its working principle seems ridiculously simple and I'm up for the challenge. There is one thing that I would like to clear up ...
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1answer
45 views

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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1answer
41 views

How do I find the Thevenin voltage and resistance equations of this circuit?

How do I find the Thevenin voltage and resistance equations of this circuit, with respect to the terminals U and G when Rc, Vc, Rt, and Rtrans are given?
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0answers
67 views

Finding equivalent capacitance and resistance from DC circuit with combinations of R and C

In order to get the simplest RC circuit and get equivalent circuit tau: How can be its transient studied if before t = 0 there only exists one resistive part of circuit? I's obvious that before t = ...
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2answers
93 views

How to take resistance reading when value is effected by measurement?

Context I am trying to measure the wiper resistance of a potentiometer. This is performed by leaving the potentiometer wiper in one position, and measuring from each terminal to the wiper (\$R_1\$ ...
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1answer
96 views

BJT amplifier design with input resistance, output resistance, and open-loop gain requirements

so currently i'm designing a BJT Amplifier with these requirements: Open-loop gain = 35 dB Input resistance = 600 Ohm Output resistance = 200 Ohm Another thing is the only BJTs I can use have hFE of ...
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1answer
51 views

Calculating inner resistance of a linear dipole

I've been stuck on a question for a while now, so I'd really appreciate if you could take a look at this: I'm supposed to calculate the dipole's inner resistance. I've got that E= 15V, R1= 1200 Ohm ...
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3answers
103 views

What is the value of the given resistor?

I tried checking with 5 band color code but was unsuccessful. Resistor is blown hence the value cannot be determined using multimeter.
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1answer
52 views

How to find current through series of potentiometers, and if it is safe for potentiometers? (Arduino)

I have 9 potentiometer with the specs: 10k Ohms and 0.5W I'm using an Arduino Mega, and using it's 5V port output to power these potentiometers in series, and I saw online that the max current this ...
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2answers
39 views

measuring resistance on hv transformer

I need to verify the resistance on a HV transformer that receives 208v single phase through terminal 1 and 2, or 240v through terminal 1 and 3 and delivers 4000v through terminal 4. As per the ...
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1answer
75 views

Can a 125mw dual gang pot handle 10w audio output?

I want to build balance control for two audio amplifier circuits, and I want to use dual gang pot. I want to know if I connected it directly to the outputs of the two audio amplifiers circuit then to ...
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1answer
38 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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2answers
96 views

Measuring the resistance of USB car chargers

I have a few USB chargers that are powered through a 12 V car receptacle. I measured their resistance with a multimeter, applying the probes to the contacts of the 12 V input. One of the chargers had ...
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0answers
41 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 ...