# Tagged Questions

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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### Trying to visualize the wording of a question about finding the resistor that carries the highest voltage

I know how to find the higgest current in the resistor, it's just the visual that I'm second guessing. This is the question. This is the what I drew from it
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### Equivalent Resistance

I'm working on the following homework problem. (Yes, this is homework. :p ) I'm supposed to find the current through L1 as a function of time. simulate this circuit – Schematic created ...
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### Does current source affect flow of current in circuit with a variable resistor?

Suppose you have a current source in series with a resistor R the current through the R resistor would be the current generated by the current source. How would the current through the circuit change ...
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We need to connect a small speaker- a headphone one, to an Microchip Pic. I don't know whats the resistance of such speaker(it's very small) but I guess it's 8-ohm. (We are only using one headphone ...
58 views

### Noise on Proximity switch signal on PLC system

I am working on a PLC based system that uses High Speed counter cards to pick up a signal from a 24 VDC proximity switch. I am having a problem with short duration 10 to 15 volt spikes being seen on ...
66 views

### Preset ratings for a comparator circuit

1)What are the rating for these kind of presets? I need the maximum current they can withstand without any harm, (Imax). [data need for a 100k preset] 2)I'm hoping to use this kind of ...
78 views

### If voltage is the same across each resistor in a parallel circuit, what's the point of resistors if there's 4 of them in a ciruit with 50volts

If voltage is the same across each resistor in a parallel circuit, what's the point of resistors if there's 4 of them in a ciruit with 50volts, it won't affect the voltage. I also noticed that when ...
346 views

### Why use a resistor in filter circuits

Since capacitors and inductors can filter on their own. Why are separate resistors needed? For example in a RC circuit, using only a capacitor would be different in what manner?
68 views

### inverting op-amp circuit

Why is -Vout equal to the voltage going through Rf? here is a link to a site which explains the inverting amplifier circuit but I couldn't understand why this is.
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### LEDs through Arduino Uno [duplicate]

I know next to nothing about electric engineering, so I got the Arduino Uno R3 and a bunch of LEDs to play around with and hopefully learn something. I have no idea about the proper terminology or ...
195 views

### Need help calculating resistance for transistor base

I have 3 12VDC/40A automotive relays (datasheet) that I want to use with my Arduino. Based on the tutorial I am following (link) I need transistor, resistor, and diode. I am not an electrical engineer ...
170 views

### How to reduce voltage from a battery to a motor [closed]

I have a 14.8v battery and I want to run a motor on 13v. What is the best solution to reduce the voltage from 14.8v to 13v?
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### How do I calculate the voltage of a resistor after the fuse has been blown?

For example, theres a battery of 12v in a seris with R1 (resitor 1) of 49kilo ohms, then there's a blown fuse of 90uA, next is R2 of 11kilo ohms, then there's R3 of 60 kilo ohms. How do i calculate ...
83 views

### Assistance with schematic notation “R@2V” for pH monitor

I've been building a circuit I found online for a pH monitor, while most of the circuit seems straight forward I get caught on the "R@2V" notation, a guess would be maybe resistance at 2 volts? I'm ...
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### How to choose a capacitor for filtering an audio signal?

I've recently become interested in analog synthesizers and have successfully built this VCO from MFOS. The VCO outputs a signal that varies from 0 to about 10 or 12V DC at 28mA. I want to bring this ...
115 views

### How do you correlate voltage output with these values that I have collected?

I'm using a "Logomatic v2 Serial SD Datalogger" to measure the voltage output of this piezo-resistive sensor, "Force Sensitive Resistor - Square." The values are logged in a .txt file in a microSD. (I ...
145 views

### Signal rectifier - what is the use of the resistors?

In the art of electronics book, page 49, 2nd edition, they show a signal rectifier circuit (a circuit that tosses away the negative part of a signal). Here it is: simulate this circuit – ...
116 views

### Pulldown Resistor on a Unity Gain Buffer

I have a sensor connected to a simple unity gain buffer with its output connected to an Arduino analog pin. I'm trying to work out if there's a way I can stop the Arduino reading jumping around when ...
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### Spice definition of resistor/capacitor

I am trying to understand a Spice definition of a circuit and transient analysis on it. I have kind of "inherited" this and can't ask the original creator; my Spice memories from university are pretty ...
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### Why is there a voltage drop across the load resistor in an ideal diode clamper circuit?

Consider a clamper circuit with an ideal diode, a capacitor, a load resistor and an AC input supply. When diode is in forward bias configuration, it must conduct and behave like a short. We must then ...
477 views

### Why does my resistor get warm?

I am currently using 150R series resistors to limit the current to each segment in a 7 segment display. I picked 150R because all the online "led resistor calculators" suggest this value. The power ...
296 views

### Measure resistance accurately with an arduino?

I'm looking at performing accurate temperature measurements with a three wire RTD, and I'd like to be able to measure the resistance and thus the temperature using an arduino. The accuracy I'm looking ...
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### Simple circuit with resistors

Knowing that I1 = 100mA, I3 = 300mA, UR2 = 10V, determine R2. So I tried it like this: we know that in parallel connection, the voltage stays the same so UR2 = UR1 = 10V. Then, R1 = U1 / I1 = ...
282 views

### How do I determine the phase response of a high pass filter?

I am stuck trying to determine the phase response of a high pass filter. I was able to find the transfer function for the high pass filter and the magnitude but I am stuck finding the phase. I found ...
166 views

### Differential Op Amp

I am trying to use a Differential Op Amp to receive and transmit over a Differential Signalling Bus. I am basing this on this excellent op amp tutorial. The Bus I am using has has 2 lines, Low(v1) ...
334 views

### How do I determine the inductance of a circuit using Op-amps, Capacitors and Resistors?

I am trying to prove that the inductance of a given circuit (between the source A, and ground) (see image below) is equal to (R1*R2*R4*C)/R3. Under the assumption that it is an ideal op-amp, I know ...
171 views

### Beaglebone Black ROV Control Scheme

I am looking for some advice regarding my control setup for an ROV and how to make it as smooth as possible. Currently, I have two arcade style joysticks with standard micro switches inside. How I ...
103 views

### Replacing resistors with equivalent resistor

This is somewhat a homework assignment, but please bear with me. Given the following schematic, I want to know the overall resistance when measured from node A to node B. simulate this circuit ...
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### Step Voltage Down

I have an Arduino and several Strings of LEDs being powered by a wall wort. The LED portion is fine as is, however the Arduino has an ethernet shield attached and it is getting very hot when on. The ...
213 views

### Voltage divider with lower ohm rating

So I was creating my own circuit based closely off the minty boost charging diagram for iDevices and I had slightly messed up on my calculations. If all my math was correct, I accidentally bought ...
155 views

### How should I connect four resistors to double the capacity with the same resistor? [duplicate]

I know that putting two resistors in parallel will double the wattage from the input to output, but only with half the resistance. Example Parallel Circuit: simulate this circuit – ...
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### Voltage output in ripple filter

we got this ripple filter circuit as shown in this figure.Input voltage $$V=v(1+\cos (\omega t))$$ is fed to left input and then find output voltage. Now this problem confuses me. For instance ...
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### How to set a resistance between two points by a digital input

For context, this is my first real delve into electronics. For my current project, I need that varies the resistance given input from an arduino. What I was trying to do was, in conjunction with a ...
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### Calculating reflections

I just solved a problem in my homework. I had to calculate the reflection waves and I was given the following data: // Resistance R0 = 120 Ω line impedance Ri = 90 Ω resistance at input Rb = 1 ...
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### I have a “typical” 5 ohm resistor. Is there any way I can know the max power it can handle without the smoke test?

I need a 5 ohm resistor that can handle 5 watts. I don't know if the one that I have (a typical one, if that can be said) can handle it. Here's an image of one: I do not have the datasheet ...
61 views

### measure resistance circuit when I have an lm334

I have a circuit simulate this circuit – Schematic created using CircuitLab this circuit without the lm334(current limiter) should produce some kind of voltage on R6 when R5 and R4 are ...
109 views

### I don't understand how the resistor between GND and the source in a common-source amplifier stabilizes it

See this circuit: Applying KVL around the gate-source-GND-gate loop, I get Id = (Vg - Vgs)/Rs. I know the typical argument begins with, if Id increases then Vs increases, but I am not sure of how ...
138 views

### Is a resistor needed for LEDs in this beatbox project? [duplicate]

I'm making a LED beatbox (seen on Kipkay.com). I'm using 8 LEDs (5 millimeters, I don't know if this helps) and my power source is 12 VDC 800 mA. Do I need to add a resistor? If yes, which one should ...
237 views

### Basic help with calculating values for PN2222A LED circuit

I'm gonna be adding an IR LED to my Arduino Uno and I'm trying to wrap my head around the math used to figure out the exact resistor values needed to use a PN2222A transistor to drive the LED. I know ...
275 views

### Why do RC circuit voltages decay *slowly* rather than instantly?

Let's take the simplest RC circuit imaginable: simulate this circuit – Schematic created using CircuitLab Now I think I properly understand why the voltage rises slowly after the leading ...
152 views

### Powering large LED array

I have a large LED array (huge, actually). It's 38 rows x 76 columns (2888) LEDs in total. The LEDs are 3mm, rated at 2.0 forward voltage and 20mA. The 38 rows (positive) are multiplexed using ...
569 views

### Reducing the tolerance of resistors manually

All the resistors available come with a finite amount tolerance. This is undesirable particularly in highly sensitive systems. While we can use resistors with the least tolerance available, I want to ...
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### Missing resistors…

I apologize if this type of question doesn't belong here, but I recently completed a circuit diagram for an upcoming project, and realized upon review that I didn't include any resistors... There ...
126 views

### Reusing old circuit components

I have some circuits and I want to get and reuse some of its components. How can I determine if I can still use that capacitor, diode,resistor, thermistor and many more components by using a ...
95 views

### Pros and cons of using resistor networks over individual resistors?

I've been looking over some board designs and have been trying to identify the reasons behind using resistor networks over individual resistors. Some guesses I can think of are a reduced part-count ...
77 views

### Choosing values of resistive divider, versus pullup resistor value

I have a slight Catch-22 with my circuit portion shown below. The ADM6320 is, among other things, an undervoltage detector with factory threshold of 2.93 V (thus Reset output pin toggles when VCC ...
118 views

### Connecting an always on LED to a raspberry pi [duplicate]

I'm new to electronics, so I thought I'd start simple and just connect an LED to the GPIO on the raspberry pi, to pin 1 (3.3v) and the ground pin. But I'm having trouble calculating the resistor I ...
185 views

### Does a power supply GND connection need a resistor?

I am creating a power supply for my work station, and I have a input of 13.5 - 19V DC from a converter on POWER_JACK. From this input voltage I want to derive 12V, ...