Questions tagged [resistors]

A resistor obeys Ohm's law (V=IR); the current through it is equal to the voltage across it divided by the resistance (equivalently \$I=\frac{V}{R}\$)

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Choosing right values of resistor for transistor as switch

I've built something like this for using MCU pins as a joystick controller for a Sega Master System (and the pins are driven from a USB HID device connected to the MCU, but that doesn't matter). The ...
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LED doesn't turn off as intended in sound sensor circuit

I am using a sound sensor and would like that when sound is detected by the sensor, an external LED also reacts to the sound and flickers to the sound. The connections for the LED is the positive pin ...
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Connection between Analog GND and digital GND

While studying the following schematic I see that AGND and GND are connected with a 0R Does it make any sense? Why not just use a common GND? The 12V power supply input has a 100R resistor with an ...
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Why do we need to use a 100ohm differential probe to measure ethernet signals when there is not any standard?

I was going through the debugging techniques of ethernet signals and found that we can capture the ethernet signals using a 100ohm differential probe. Why do we need to add 100ohms on the ...
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1 answer
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Using nichrome as a conductor?

Can we use nichrome as a conductor by connecting it in parallel with a small resistor such as 1 ohm resistor to lower its resistance?
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1 answer
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DDR3 Termination Resistors and VTT Capacitors

I have a DDR3 implemented in our current design with 50 Ohm 0402 termination resistors and 0.1uF 0402 decoupling capacitors to VTT on the address, data and control lines. The design is working well ...
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1 answer
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Is there elastic resistor material?

Is there elastic resistor material? I want to measure the respiratory rate and smoothness of each breath. And it would appear that a brute force solution to this problem could be a belt around the ...
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3 votes
2 answers
150 views

Is there an affordable way to balance a bridge without using expensive resistors?

I have a full and balanced bridge circuit with four through-hole \$ 350 \,\Omega \$ resistors and an instrumentation amplifier AD8293G80 that has a gain of 80. Both the bridge and the amplifier are ...
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4 answers
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In a basic Ohm's Law circuit, is the effect of the resistor localized?

Elaborate way to put my question: Why is the current before the resistor and after the resistor same? Since I'm taking beginner taking classes about electricity, this is what I know about circuits. ...
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2 answers
146 views

Small electrical water heater

When I was much younger than my current 64 years of age, I saw water heaters made using simply two single electrical 110 V wires and some form of a connection between the two, to simply stick in a cup ...
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1 answer
102 views

What are the maximum recommended values ​for SPI/UART/USB series resistors?

Almost always in electronic designs resistors are used in series in the SPI/UART/USB connections to avoid overshoot, and they are encountered in values ​​between 10R and 350R. With what criterion ...
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How to calculate op amp output voltage

I have the following circuit: If I feed the circuit with 10 V all I get is about 8.2 V when VFD > 3.3 V. How is the resistor divider calculated (R94 and R95 + RV1) so I can get a voltage as close ...
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132 views

Is there a contradiction between these two definitions about an op amp?

This image shows the inside of an op-amp: But I read in a website that: The standard 741 Op-amp circuit contains 20 transistors and 11 resistors. Why does this image does not show these transistors ...
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1 answer
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Control LED strip with microcontroller using n-channel MOSFETs

I am struggling to set up the wiring for controlling a LED Strip using MOSFETs. I have seen a lot of different tutorials. According to this tutorial for example, source and gate are connected with a ...
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7 votes
2 answers
945 views

What is ohm joules unit used for? [duplicate]

I found following component but don't know what it is. In particular what does the ΩJ unit mean?
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RC Circuits with multiple resistors clarification

If I were to have a RC current with multiple resistors but placed at different locations (following examples), would the voltage across the capacitor once it is fully charged always be equal to the ...
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2 answers
132 views

How do you calculate the total resistance here?

I have three resistors in an inverting operational amplifier and I should compute the Vout with the total resistance of those 3. Should the Rf/k be considered connected in parallel with those 2 Rf? My ...
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2 votes
0 answers
75 views

Electronic components pressure rating [closed]

I have made a custom PCB that measures acceleration. The PCB contains components such as op-amps, SMD resistors, COG capacitors, and tantalum capacitors. The circuit is powered by a saft ls14500 AA ...
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2 answers
204 views

Reducing signal voltage with pull-down resistor

I have a signal that is really high compared to the inputs of a microcontroller and i have to step it down a bit.... Can I use a pull down resistor between the signal and the GND? Will this step down ...
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1 vote
2 answers
136 views

Can you place a large series resistor on the input of an LDO?

I would like to use an RC filter to filter out noise, since the down stream components only needs a maximum of 30mA. Is it possible to use such a large resistor on the RC filter to achieve very low ...
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CAN bus termination resistor

I'm trying to design a CAN device where the user can select which device is the beginning/end device and activate the 120 ohm resistor accordingly. I've seen some examples using a switch, but I'm ...
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1 vote
1 answer
104 views

Diode in series with a resistor an in parallel with another resistor

I have been facing some troubles with this problem. My main concern is that if Vab = 0.7 (when V(t) > 0 V,) will the diode conduct? I think that isn't the case, but if that so I don´t know how to ...
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8 answers
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How can a resistor have an effect on a circuit if it leads directly into the ground?

I'm new to electronics and I'm coming from a programmers perspective so sorry if this is obvious. ][1 This is a voltage division circuit (just a simple example from wikipedia.) R2 leads directly into ...
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1 answer
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What is the net current through this LR circuit

Here is the problem which I was asked to do. I started by the method of phasors considering first the upper branch of the circuit Drawing phasors as follows : Then for the lower circuit i drew the ...
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1 vote
1 answer
184 views

What is the purpose of an input resistor or load resistor in a voltage/current amplifier circuit model?

From what I understand the source input will have some internal resistance. So a what is the function of an input resistor or load resistor in a voltage/current amplifier circuit model? How do you ...
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1 vote
1 answer
95 views

Need help on resistor calculation

I'm currently work through an application note from Texas Instruments about building a programmable power supply. The base concept is fine and I understand it, now I'm trying to go through the ...
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2 votes
1 answer
103 views

Current source controlled by an external resistor (Inside an IC)

I would like to control an internal IC current using just an external resistor. The typical schematic would be the following: However, this method has at least two disadvantages: For Vdd=3.3V, ...
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2 votes
3 answers
721 views

What causes the 7 volt peak in this 5 volt RC circuit, and why does a diode alleviate it?

I was reviewing this question on an RC circuit design from a Ben Eater video, and came across hacktastical's answer on how it was a bad design because it outputs 7 volts on release of the push button (...
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1 vote
3 answers
135 views

How do I calculate the equivalent resistance of this type of circuit?

. I get the overall formula, I'm not sure what to do about the 1 mF and the 1000 μH. Do I convert them in some way or ignore them? What if I'm trying to find total power dissipated or voltage across ...
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1 answer
100 views

Selecting MOSFET and resistors for high side enable switch

I've been working on a hobby project and recently got help from this community on input power source switching. I'm supplying my AVR based PCB with USB or LiPo battery power (with an MCP73831 based ...
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2 votes
3 answers
236 views

How to parallel shunt resistors with 4-terminals (Kelvin connection)?

I would like to use multiple shunt resistors in parallel to reduce power dissiption to the power specified per resistor. However these resistors are 4-terminal resistors WSL40265L000FEB. The reason ...
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2 votes
1 answer
98 views

Appropriate circuit for activating relays

I am trying to use two G5V-2-DC5‎ relays to switch four wires at the same time between two different outputs. All signals are 5 V. I've gotten this to work fine with a simple physical switch but want ...
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1 answer
59 views

How to I optimize this LED circuit?

The Project This part is pretty simple: I'm building a stunt lightsaber up from scratch. The led is held in a heatsink housing inside a 1 inch (internal diameter) aluminum tube. The heatsink is rated ...
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0 answers
54 views

Is resistance of a 12V source down to 0.5V and 0.1mA even possible using E12 Series resistors?

I am stumped on this question out of my textbook, its about finding the value of a resistor for a circuit given the source voltage and device requirements in Volts and amps. In this case its 12V ...
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1 vote
1 answer
96 views

Thevenin equivalent in a diode circuit with ground between resistors [closed]

I'm trying to find the Thevenin equivalent of this circuit with respect to the diode. I know the steps needed to find Vth and Rth and I was able to find Rth already (2.2222k) but I'm having a hard ...
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2 answers
127 views

Why I am I unable to turn on a load when Wheatstone bridge is connected in series with the load

I am trying to switch on a load by using a Wheatstone bridge and planning to provide the differential voltage to the transistor. Before doing that, I am trying to use two batteries (second one ...
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-1 votes
2 answers
50 views

Should I trust a Power Adapter to directly run a pump? [duplicate]

After some research and head-scratching, I plan to connect a 3 Pin UK AC/DC 4.5V 500mA 0.5A Power Adapter (5.5mm x 2.1mm) into a 5.5mmx2.1mm 2 Pins DC Power Jack Female Connector Socket and that ...
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0 votes
3 answers
103 views

Voltage drop on resistor with MOSFET configuration circuit [closed]

I have big misunderstanding in calculating voltage and current across resistor in next circuit. I think picture well represent my question. The amplitude of V1 is 3.3 V.
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129 views

What is the value of these resistors?

Two resistors in a Bosch AL 1115 CV battery charger 127V burned up yesterday, and I am trying to figure out the correct value to replace them. I have found in the internet this photo where I suppose ...
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2 answers
183 views

Why do you need resistors for components, like ADS1115?

I am trying to design my first own PCB and before I always have used breadboards or Prototyping boards. On them you use smaller PCBs, that come with the components on it, to connect it to you circuit. ...
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1 answer
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SMD "power" resistors : what constraints on PCB layout

I'm looking for current sens resistors. As those are rather big (and beeing for now the limiting element for my PCB size), I would like to stop using over-rated one and take some with "just" ...
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-2 votes
1 answer
157 views

How to find nature of RLC circuit?

If a resistance value, XL value and XC value are given, how do we determine the nature of the circuit (whether it's capacitive, resistive or inductive)? The only thing that comes to my mind looking at ...
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-1 votes
1 answer
75 views

I am adding 1 ohm resistor with a coil in series and an connecting to a 25 W DC source. How to choose the correct resistor of 1 ohm?

I am adding 1 ohm resistor with a coil in series and connecting to a 25 W DC source. How to choose the correct resistor of 1 ohm? Is 1 ohm, 25W resistor is OK for this circuit? Please help. Edit from ...
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1 vote
2 answers
166 views

Is it possible to make a XNOR gate only with diodes without using a transistor?

I created almost all logic gates with diodes and resistors NOT, OR, NOR, AND, NAND, XOR but i have problems with XNOR and i doubt if it is even possible. I found one but this using a transistor, so my ...
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2 votes
1 answer
173 views

Apply superposition principle to compute current in the 2 Ω resistor

So in this question what I tried to do was first remove the 6A source and then try to apply the current divider rule according to which the current I = 24 x (4/12) = 8A and then remove the 24A source ...
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2 answers
111 views

Why are the resistors compulsory in this circuit? [duplicate]

When I use resistors, my circuit is working fine but if I remove them, then the LEDs in my circuit don't work anymore. As seen here the switch just sends high (red) voltage ahead Can you please ...
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1 answer
118 views

I want to step down 120 Vac to use with a 12 V latching push-button switch, can I? [closed]

I want to use a latching push-button switch, specifically the Ulincos U19C1. They are rated up to 5 A and 250 VAC, and the LED is rated for 5..12 V (from their website.) According to the seller, if I ...
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0 votes
2 answers
69 views

How does voltage distributes in full wave rectifier with resistive load?

I am a bit confused with how voltages distribute themselves in the circuit, for the positive cycle the diodes D1, D2 are turned on. We have positive input voltage terminal connected to D1's anode and ...
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1 vote
4 answers
266 views

Silver band at 3rd from 5 band resistor

I need help to find this resistor value. They’re 5 band resistors and it has silver band at 3rd. I try to use online calculator but can't calculate this silver 3rd band. It’s a faulty resistor so I ...
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2 votes
0 answers
183 views

Typical parasitics values of thick film SMD resistor

I'm looking for values of parasitics for SMD thick thilm resistors (the cheap and readily available). Values of the following model Closest I found is this application note from Vishay, but it is for ...
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