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}\$)
3,691
questions
4
votes
4answers
182 views
How does one know that the current is flowing downwards through the \$8 \ \Omega\$ resistor?
I'm currently studying the textbook Fundamentals of Electric Circuits, 7th edition, by Charles Alexander and Matthew Sadiku. Chapter 1.7 Problem Solving gives the following example:
Example 1.10
...
1
vote
1answer
29 views
What is the difference between LDA 210 and LDA 212?
Do you see any difference between LDA210 and LDA212?
Can it be that a factory produces the same product with different names?
LDA210 datasheet: link
LDA212 datasheet: link
Official comparison ...
0
votes
0answers
22 views
Calculating the change in output voltage as temperature changes the control feedback resistance
I am trying to calculate the new output voltage when the temperature changes the resistance of the feedback network which sets the output voltage.
I have this circuit using the MCP16311/2 buck ...
-3
votes
2answers
93 views
How can I solve this opamp circuit?
I am designing an Analog Front-End circuit for an NTC Sensor which has 3 parts, the non inverting stage, the low pass filter, and goes to seeeduino.
Basically the input voltage is 5Vcc and I need to ...
0
votes
1answer
91 views
Voltage issue on pull-up resistor
I have an I2C sensor circuit, 3.3V applied to SDA and SCL pin through 10k resistor.
I2C communication is not working so I have measured the voltage drop across the 10k resistors. It drops 2.86V and ...
0
votes
0answers
42 views
SMPS power supply - fuse resistor calculation
I'm designing a TNY288-based SMPS. My transformer input inductance is 931μH. I'm using a 320V MOV and have a doubt about the fusible resistor calculation.
The output load is 12W, the input capacitor ...
0
votes
3answers
75 views
What size does my resistor have to be for the IC input?
I am testing some logic gate ICs to include in future projects. However, even when both of my switches are off, my logic IC is still sending a logical HIGH to my LED.
I think my problem is the same as ...
0
votes
0answers
15 views
Source Transformation Finding TEC
I have been trying to find the thevenin equivalent circuit with respect to nodes a and b using source transformation. I end up having this setup. What would possibly be the next step I should do? Can ...
0
votes
0answers
52 views
Resistor identification of crock pot
I'm having a problem with my crock-pot: the device turns on, but when selecting anything, it just turns off. Opened it up, and found the pictures below. I think resistor R49 is the problem - but since ...
0
votes
0answers
37 views
Are 4N35 optocoupler clamped at 22V?
I am trying to detect mains with an ESP32, for that I started testing this circuit:
I bought a 4N35 optocoupler and 110kΩ resistors.
My first test was using 2 resistors in serie, so R1 = 220kΩ
The ...
-2
votes
1answer
53 views
What is the difference between making a resistor based keypad and not using a resistor on arduino? [closed]
I've seen videos on youtube about how to emulate a keypad on arduino. Some of them includes a resistor while others do not. What are the difference between them and are there advantages in doing one ...
0
votes
1answer
55 views
My light-dependent resistor gives a fluctuating serial output
I'm a high school student trying to make a light tracking single axis solar panel. I am using an Arduino Uno rev3 board.
When I first finished building it, the system failed to operate. I spent a few ...
5
votes
4answers
573 views
Averaging thermistor readings
I have 9 thermistors arranged in a grid, and I want to average the readings from these thermistors without code (that is, average them in a circuit rather than reading all the values into a ...
4
votes
1answer
840 views
Why does this resistor not exist?
I have a 5W 5-banded resistor that shouldn't exist according to the color code chart and I've never come across this before.
The color bands are brown, green, silver, gold, black. Now looking at it in ...
0
votes
4answers
70 views
E Series: is there any place that explains it?
So I am doing a work on optimizing circuits, and I came to study the E series of components.
I'm a bit confused and I cannot understand soem things:
How do the tables of values (E3: 1.0, 2.2, 4.7) ...
0
votes
1answer
78 views
Parallel RC circuit differential equation for a mechanical engineer
For a mechanical engineering course in controls, I was asked to
Write the differential equation, state equation, and transfer function for this circuit
That's the full text of the problem, and the ...
1
vote
4answers
163 views
Resistor in my AC LED circuit gets fried
I have designed a dead simple LED circuit I calculated the required resistance to be (220-2)/0.02 = ~11k so I used 10k+1k resistors in series but for some reason, ...
1
vote
0answers
51 views
Reducing 12v to 5v with convertor
To start, I'm a complete layman on this topic. If I say something that sounds inaccurate please do correct me. I'm here to learn as much as I'm here to ask for help.
I have a truck with aftermarket ...
0
votes
3answers
96 views
Can I reduce AC current to vent from from 3A to 2A?
I have a range/stove hood with a really strong and loud blower motor.
It's so strong that when we moved into our small house, the inspector made me disable the highest 3 speeds/CFM fan levels (600CFM) ...
1
vote
0answers
103 views
Replace LED with resistor in Christmas light string
A rodent chewed up an LED socket on a 100 light, warm white 3.2 V light string. I want to replace the socket with a resistor to keep the string within its voltage and current parameters. What would be ...
0
votes
1answer
69 views
Looking for help identifying a resistor value
A resistor has burnt out in my heat sealer.
Can anyone help confirm the type? From what I can find online it seems to be a 89G Ohm - is this correct?
The body is 17 mm long.
0
votes
2answers
58 views
Getting current and voltage on a resistor using simplification
I hope it's okay if I ask it here, but I've been playing with this current for quite some time now, and I've reached a dead end.
I am supposed to find the amperage and voltage of a specific resistor (<...
3
votes
3answers
202 views
Resistive divider as resistors approach 0 ohms
Resistive divider when R1 = R2, split voltage in half because V = IR, and resistors in series add as Rtot = R1 + R2. It seems like this must break down as R1/2 approach 0 ohms. Anyone have a good ...
0
votes
2answers
81 views
How does a pull up resistor change a voltage divider calculation?
I am using this proximity sensor with a raspberry pi. the sensor outputs a 24V signal when triggered, which I need to step down to 3.3V using a voltage divider so as to not blow out the pi. The ...
2
votes
3answers
985 views
What are these components used for in the Arduino Nano?
What are the functions of the component(s) in the:
red
blue
green circle?
And what is a "+5V auto selector"?
https://store.arduino.cc/products/arduino-nano
0
votes
2answers
61 views
Resistors max AC voltage datasheet
I want to make this circuit:
Where Sens2 is mains (233VAC in Switzerland)
I found this resistor that look perfect for the job: RND 155SP12 3W (datasheet).
I don't understand what does max voltage ...
0
votes
2answers
69 views
What type of resistor is needed for 5V 2A power? [duplicate]
I am new to electrical engineering. I need to power a control board that requires a 5V power supply. The instructions specify "5V 2A or 4A". I have a USB port that specifies a "max of ...
-2
votes
2answers
82 views
Easiest way to make a resistor [closed]
What do I need to make a resistor of about 10 kΩ? After I make it, how do I measure the resistance with this device:
-2
votes
4answers
220 views
I'm new to circuit analysis and completely stumped on this circuit. Could someone please help me understand the steps to solve it? [closed]
I have to calculate the current and equivalent resistance but I don't even understand where to start. I'm not looking for a straight out answer I just want to know how I should go about solving it?
3
votes
1answer
112 views
Resistor between 74595 SRCLR and GND
What is the function of this resistor and is it okay with this value ?
Rizki
3
votes
6answers
2k views
Why do resistors "draw" current? [closed]
I was looking at an explanation for why parallel resistors have less resistance:
Resistors in Parallel
One of the answers involved simulating parallel resistors as a black box and it made sense.
If ...
0
votes
0answers
24 views
Converting Delta-Wye to Wye
To convert the delta part of this circuit to wye, is it correct to do (6-8i)/3 and then to combine the two wyes, as they are in parallel, do (6-8i)/3 // (4+3i). Then will this form one wye which is 2....
0
votes
1answer
31 views
Calculating capacitor voltage with initial conditions in an RC circuit
If the initial voltage of the capacitor at 0s is 20V, would the equation for the voltage of the capacitor at a specific time be; 60 + (20-60)e^(-t/RC)
or would it be 80 - 60e^(-t/RC)
0
votes
2answers
48 views
Identifying Parallel Resistors from Series
I have this circuit that I am analyzing, but I am a bit confused about how the resistors are connected here. One end of the 200 ohm resistor is connected to the 50 ohm resistor while the other end ...
0
votes
4answers
94 views
Buttons in parallel - short circuit? [closed]
I encountered a problem while trying to use 21 buttons at the same time. Initially, I did not take into consideration that they could be pressed all at once. And while measuring the resistance I ...
0
votes
3answers
95 views
Transistor resistor calculation help (design revision 1)
I posted my original design yesterday and got many comments about my errors. This is revision 1 of my design. I am now pretty sure I have the load resistors calculated correctly, but still unsure ...
-1
votes
1answer
92 views
Why is my piezo buzzer emitting a clicking sound?
I'm trying to make a voltage controlled oscillator (VCO.) It works just fine, but my piezo buzzer keeps clicking in conjunction with the square wave the NE555P is producing, making a weird effect. Is ...
1
vote
1answer
94 views
Transistor Resistor Calculation
I am new to electronics so I'm not too sure about how I should be calculating the base resistor to use in this circuit.
I think the load resistor is calculated correctly (data sheet at bottom for ...
-1
votes
2answers
63 views
Resistor in series with Vcc [closed]
Suppose I have an IC where I connect a series resistor with Vcc and '+Vcc' supply pin of IC. Refer to the schematic above.
Say the IC current consumption is in uA or few mA for a supply voltage of 3V, ...
0
votes
1answer
50 views
Protect high voltage little currents
Short question:
Are there alternatives to very low currents fuses? I need something that breaks at about 6 mA. and I cannot find anything like that.
Long question:
I am trying to detect mains (230VAC) ...
0
votes
1answer
148 views
Why do two different approaches give different results about choosing resistances for voltage divider of emitter follower circuit?
I have read this page from the Practical Electronics for Inventors book.
What I don't understand is about the calculation of R1 and R2.
Approach 1:
This approach is author's idea and the result is R1 =...
0
votes
1answer
67 views
Replacing 1k resistor [closed]
I just bought new soldering station, when I turn it on the solder some thing burned inside the soldering station.
When I open the soldering station I found out that 1k resistor burned out.
Do I ...
0
votes
1answer
64 views
How to solve this resistance calculation question:
I need help to solve this question, the first part was to solve for the missing currents which I have done, and the second part is to calculate each resistor value.
On the left is the circuit given on ...
0
votes
1answer
48 views
Question regarding equivalent resistance
I am looking at an example in my text regarding Thevenin circuits and when they set the voltage source on the most left hand side to zero and solve for the equivalent resistance they get the following:...
-1
votes
2answers
72 views
Sine wave signal lagging; potentiometer has inductance? [closed]
my sine wave at the midpoint of potentiometer is lagging by 74 degree when comparing to the input, and my potentiometer is 500Kohm. Is there a low inductance potentiometer?
I do not know how to pick a ...
3
votes
8answers
794 views
Time constant of this circuit
Can someone tell me on why the time constant of the below circuit is not R2*C?
simulate this circuit – Schematic created using CircuitLab
My understanding is that, the Capacitor C1 is getting ...
1
vote
1answer
47 views
On what factors does the I2C pull up resistor values depend upon
I was reading this Article regarding the pull up resistor calculation.
I understood that the value of the pull up resistors depend upon the currents, the supply voltage and the Logic Level voltages ...
0
votes
1answer
66 views
Variable resistance controlled by micro controller
I wish to remove 2 resistors in power supply unit and put variable resistors that would be controlled by my microcontroller.
1st resistor should be in range of 3000-6000 Ohm
2nd resistor should be in ...
0
votes
0answers
28 views
Looking for a formula to calculate the resitance needed to make a proximity sensor shorter! RCWL-0516
I want to decrease the range of this cheap sensor dramatically from 5m to 5cm! Im not sure which equation I use to calculate this. I'm assuming but not sure if there is a bigger resister value that I ...
0
votes
3answers
56 views
Using shared pull-down resistor or providing pull-down for each mosfet
There are some P channel and N channel mosfets which operate as swiches in figure 1. Also, there is a pull-down resistor for each mosfet which prevents the mosfet's gate being float when the VCC is ...
