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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2
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4answers
247 views

Can a 10% resistor be used as a 1% resistor?

If my schematic calls for a 1% resistor, can I use a 10% resistor that measures to the correct resistance within 1% or is there some quality to tolerance beyond what it measures Ohm-wise? For ...
0
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0answers
26 views

Explain to me how values are read with pullup resistors [duplicate]

In the above picutre, it seems to me as if when the switch is open, a voltage of VCC is on the input pin (i.e., voltage comes in through the resistor, to the input pin then back to GND through the ...
0
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0answers
42 views

Tennis court lines, which sensor do I use to detect a ball?

I would like to make tennis court lines with a pressure/force sensor underneath them to detect when a ball is landing on them. On the internet I could only find very short pressure sensor that where ...
0
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1answer
74 views

Transistor amplifier circuits

What is the ac collector resistance for the transistor Q1? I am having trouble finding which resistors are in parallel with each other in the circuit above. I want to find the voltage gain and power ...
1
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1answer
65 views

Wired vs SMD resistor on 230V optocoupler input

For circuits similar to the one below, we used large wire resistors with proper power rating in our past designs. The question came up, if it would be a good idea to replace the resistor with SMD ...
0
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2answers
73 views

Fuse: why does it connect in parrallel with resistor?

I have a wire in normal condition runs 4A. The device I am using is auto-transformer, and its data sheet recommend to use fuse of 10A. So I went to buy the 10A fuse, and mount it onto a fuse holder. ...
1
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1answer
84 views

How to solve first-order RC circuit?

I've got a question, and I just keep getting myself confused when I try to solve it. The problem asks to find voltage and current and resistor currents transients (the switch is opened at t=0). ...
-5
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0answers
52 views

Basics doubts in Circuit theorey [on hold]

Can somebody explain me briefly on different methods of grounding with examples? Chassis ground , Earth ground , Signal ground. Basically if a circuit is grounded, how does electrons flow? To ...
0
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3answers
100 views

Why does a closed circuit with a pull-up resistor output “0”?

I have a switch setup with a pull-up resistor. With the switch open I get a "1" or HIGH output and with the switch closed I get a "0" or LOW output. I understand why I am getting the "1" with it open ...
-2
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0answers
76 views

Power circuit analysis [closed]

2 questions 1) does anybody on this website have any knowledge of transformers and power system? (just to make sure i'm not on the wrong site) 2) can someone explain how to draw a transformer ...
0
votes
2answers
53 views

Calculate resistor for red Led in series

Hello guys i am really confused about the whole resistor issue. I have visited so many sites that tells you what resistor you need but i don't know the volt drop that asks to complete or the current. ...
0
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0answers
38 views

Transformer equivalent circuit [duplicate]

If anybody has any experience with practical transformer schematics and analysis techniques, could you please explain how to solve this question, i have looked all over multiple websites and there is ...
0
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1answer
45 views

Two-port network Current Characterization

I was trying to solve this two-pole exercise in which I had to found the z-parameters but I haven't find any clue in the textbook. How should I solve it?
-1
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0answers
35 views

Low-pass RC-Filter with load problem

this is my first time posting here so my apologies in advance for any missteps. I have a homework problem where I am trying to find the Gain of the system. The circuit is similar to this one: ...
3
votes
3answers
261 views

Control Power Resistor with MOSFET

I am making a temperature control system using an Arduino. However, I have a problem with controlling a power resistor (which is used as a heater). I was suggested to use a MOSFET to control it. ...
0
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0answers
53 views

RGB LED array without current limiting resistors but PWM

I found this blog post, where it says: Alternatives to using current limiting resistors: Resistors are a simple way to limit current, but they are not efficient. Excess power is wasted as ...
0
votes
1answer
50 views

What is the equivalent resistance in this part of the circuit?

I broke the circuit down into as basic as I can take it, and I know what X and Y are, but I can't figure out the equivalent resistance of the circuit in the middle. It seems to me like the current ...
-1
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1answer
86 views

Need help with power resistor [closed]

I need to building application where i need to heat aluminium block. Aluminium block will be chilled with water chiller system. This application need to work ~ 2 years 24/7. All this time i need to ...
0
votes
2answers
59 views

Resistance as a function of base voltage in a transistor

In this very interesting introductive video https://www.youtube.com/watch?v=CkX8SkTgB0g, I learned that a transistor is basically nothing more than a resistor whose value changes accordingly to what's ...
0
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3answers
461 views

Why must resistors be on the respective anode terminals instead of the common cathode terminal of a RGB LED?

Different from the best answer of this one: Why does a resistor need to be on the anode of an LED? But well, I'm also an electronics noob ^.^ Recently I bought the official Arduino starter kit and ...
0
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2answers
129 views

Why do I need I large resistor to the GATE of my MOSFET?

I tried to control the brightness of a LED using a Linear Hall Effect Sensor fed to an Arduino, and PWM output to the gate of a MOSFET connected to a 12V battery. The LED was flickering a lot, and ...
0
votes
1answer
71 views

How to shift resistance range of Linear Potentiometers by X ohms in the Positive or Negative direction?

For example, I have a 10k ohm (linear) Thumbwheel Potentiometer. This POT will produce values from 0 to 10k when reading its resistance. Positive Shift How do I shift resistance range values by X ...
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2answers
54 views

How does wiring resistors in series and parallel affect their errors?

In an experiment I am conducting, I am trying to measure low currents by wiring a radio device in series with a small-resistance resistor setup, composed of 9 of 1 ohm +/- 5% resistors in series and ...
1
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2answers
42 views

What type of books/materials to buy to learn about breadboards, leds, resistors etc [closed]

I currently have a Raspberry pi and notice alot of tutorials online take advantage of something call a breadboard - which to me looks like a multi-purpose base which when used correctly we can use to ...
2
votes
1answer
68 views

Help with Wiring LED Parking Light/Turn Signal using manufactured Bolt LED

In my search to find the best way to complete this pet project on my truck, I found this site. I've searched but as I am using a manufactured flush mounted bolt LED lighting unit I still have some ...
0
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2answers
51 views

Resistor power rating for short pulses

Just wondering how to treat a resistor power rating if the resistor is only getting current passed through it for 1us or less? Is it reasonable to exceed the power rating significantly (say 10x) for ...
-3
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1answer
63 views

Cascaded Op-amp circuits

Any help would be appreciated.
2
votes
3answers
111 views

How to analyze this Diode Circuit by hand?

I need to analyze this circuit by hand, I'm a Mechanical Engineer, so I really have no idea what I'm doing here. I thought about doing the parallel of the 2 top resistances and same for the bottom ...
0
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1answer
36 views

Split power across three circuits with difrerent resistance and provide equal current

simulate this circuit – Schematic created using CircuitLab Me and a friend are working on a project and have three circuits with resistance (8.9k ohm) across them and a single 9v battery. ...
0
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2answers
66 views

How to calculate power requirements of LED matrix, per row or per LED?

I have built an LED matrix (9x9) and want to run it with Arduino. I am using technique of scanning, lighting up 1 LED at 1 time. The more I am reading about power requirements of a matrix the more I ...
0
votes
2answers
108 views

Current divider and capacitor

I have this circuit which looks like a current divider but with an extra capacitor. I want to know how Ia , Ib, Ic change as the capacitor begin to charge, i do know one thing after a time of 5 RC the ...
1
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1answer
88 views

Are small clay capacitors pose any health hazards?

I'm making a small activity with children where we will be using capacitors and resistors to make jewellery like earrings. Do they contain any materials that pose a skin or otherwise health hazard?
1
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4answers
398 views

Low pass filter issue - is the 10k resistor part of the circuit?

This may be a really simple question but Op Amps still confuse me a little. I have a low pass filter circuit as shown below. My question is whether the 10k resistor is part of the filter circuit ...
0
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2answers
78 views

Parallel RC Circuits For DC?

Is there any use for parallel RC circuits in DC applications? Look at this now full diagram for example. The IC has 3 pins (mosfet maybe). It seems that the resistor in parallel would only drain ...
2
votes
3answers
116 views

Resistors in paralel on pcb schematics?

I know that capacitors in parallel are used for filtering, but what could possibly a resistor in parallel be used for? Take for example the schematics I pinned to this post ...
0
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0answers
69 views

LEDs with built-in resistors

Do they make LEDs that have a resistor built-in on the anode? If not, why not?
2
votes
3answers
136 views

Resistor calculation

I'm still new to electronics and I am trying to do a calculation. Say I have a 100 Watt bulb that runs at 120V and my source is 240V. I know the bulb will blow but my question is: if I wanted to put a ...
-6
votes
1answer
149 views

Plotting Vout vs. Vin Curves for an Ideal Diode / Resistor Circuit

I am trying to plot the Vout vs. Vin for the following circuit, assuming both D1 and D2 are ideal, the forward voltages are V(D1,on) = 0 and V(D2,on) = 0.7V, R1 = R3 = 1 kOhm, R2 = 4K, and E = 3.3V. ...
0
votes
1answer
42 views

Typical Resistance Temperature Coefficient Variance between a reel of same value resistors

I have a resistor divider, I'm interested calculating the drift of the divider over temperature and if possible minimizing it. I was wondering if both resistors in the divider have the same value ...
1
vote
1answer
56 views

Are there any effective estimates for up-rating resistors power capability by adding airflow?

I'm considering using a bank of resistors similar to this: http://www.vishay.com/docs/31842/fve.pdf 300-400 watt "corncob" wirewound resistors. I understand that they can be run over their spec'd ...
12
votes
2answers
1k views

Why is the first band on a resistor never black?

I'm taking an electronic circuit analysis class, and I was asked to give the color of the 3rd band of a 1MΩ resistor. My answer was blue, thinking it could be black-brown-blue (01 * 1MΩ), but the ...
0
votes
3answers
159 views

Electronics I problem

Suppose that Vin= -∞, that forces D1 to open(OFF) and D2 to close (ON). Given E is 2 , then Vout=-2. Then I applied KVL to find the equation for Vd1 ( Off). Now I know that I have to find the ...
0
votes
3answers
55 views

Choosing the right voltage divider by load

I'm using an Android IOIO board to detect simple digital pulses from a 12v source. The input pins are 5V tolerant. Would a simple voltage divider work in this situation? I guess my concern is whether ...
0
votes
5answers
350 views

Pulsing an LED with no series resistor

I have a basic circuit using a BJT common emitter which I have constructed to pulse a red LED on to use as a strobe with 1us ON time (@12V) and plenty of time to cool down (<< 1% duty cycle). ...
0
votes
1answer
75 views

Conductive magnet to read resistor value?

I want to know if I can hook-up a resistor to one part of a Magnet Snap (carried by SparkFun), then another magnet snap to analog-pin on Arduino and still be able to read resistance value? Is this ...
1
vote
2answers
98 views

Arduino and resistors

So , hopefully this is my last question on this system it's about the connections: about the transistor, i want to use it like a switch, so i wanted to know how to determine the value of the ...
0
votes
2answers
94 views

LED resistor calculator wrong?

Planning to use a green LED (forward voltage 2V, forward current 30mA) on a 12V circuit so using as resistor calculator (led.linear1.org/1led.wiz) I bought a 390 ohms, 1W resistor. However after ...
0
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1answer
35 views

Selectively outputting 2 inputs based on a third input

I currently have 2 inputs that can be on or off, they could be 00, 01, 10, or 11. I want to output them only if a third input is active. I figured BJT transistors would do the job, but they seem ...
0
votes
3answers
86 views

Obtaining a specific resistance

first of all, let me apologise for my inexperience with electronics. Now that's over with, I'm trying to follow a guide that specifies the use of a specific temperature sensor with an output of 5v ...
1
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2answers
51 views

Hooking up an 8x8 LED board

I recently bought this 8x8 LED board from geeetech which came with this datasheet. I'm new to programming so I bought this board to "figure it out" but now I'm running into issues I don't understand. ...