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Questions tagged [variable]

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Are variable capacitors compatible with breadboards still available?

Variable capacitors are used less, since the preference is for digital adjustment. And through hole parts are used for less, since the preference is for SMD. Finally, many variable capacitors have ...
SRobertJames's user avatar
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2 votes
3 answers
925 views

Are there large-range variable capacitors?

I want to use a variable non-polarized capacitor which can vary between 10 pF to 1 μF, or at least up to 100 nF. I can only find trimming caps which can only go up to 100 pF. Am I looking for ...
pnatk's user avatar
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0 votes
0 answers
73 views

Automatically Vary LFO Speed Resistance Value

I have a basic tone generator circuit with LFO speed controlled by a 50K pot (variable resistor). I would like this resistance to fall (or rise, but I guess fall might be easier) after the circuit has ...
Jeff's user avatar
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1 vote
0 answers
50 views

Symmetric PCh and NCh MOSFETs for variable resistors

I'm wanting to build a variable voltage-controlled resistor. The resistor would be in series with a 200 uA AC current source and need to be controllable between 1-20 ohm. My current plan is to take ...
Mekala's user avatar
  • 11
0 votes
1 answer
84 views

Which one would be easier DC to DC or AC to DC [closed]

I have 440V 3 phase power that will be full wave rectified to 600V DC. My question is, would I be better off plucking one of the phases and rectifying the 120V AC to 12V DC or one of the DC rectified ...
ircsmith's user avatar
0 votes
1 answer
111 views

Integrators and the mechanics of a state-variable filter

I'm trying to understand how this topology of state-variable filter with summing amplifier produces a band-pass filter at the second integrator's output, in the context a parametric audio equalizer. ...
Domingo's user avatar
  • 109
0 votes
1 answer
128 views

Need cheap variable positive/negative switching bench power supply with CC

Just for fun I want to make a lightweight, cheap, adjustable positive/negative bench power supply. "Lightweight" means that using an old PC ATX power supply isn't suitable as a basis. ...
Mike S's user avatar
  • 153
0 votes
1 answer
89 views

Circuit analysis to understand how this circuit works - PNP

I am trying to understand how to get values at midpoint_diode and also at OUT. I understand this circuit is to step-down the voltage from Vin to something that is lower and also it used to have a ...
mdabdillah's user avatar
0 votes
0 answers
170 views

Variable voltage control from an ESP32

First, the background context: I have a pair of these TCS-300 landscape lighting controllers which have a cloud-only control interface, which cannot be integrated with my local home assistant. My goal ...
Wez Furlong's user avatar
0 votes
0 answers
65 views

Higher Resistance Measurement on Wet Tongue than Dry Tongue?

I'm trying to start learning about electrical engineering as a hobby. I'm reading from a book right now, and it suggests using my multimeter to measure the resistance of my tongue while it's wet and ...
verarox's user avatar
0 votes
4 answers
479 views

How to accurately measure a variable resistor?

I need to get a measurement from a variable resistor, ranging from 10-180 Ω. Measurement shall be better than 1% over a room temperature ranging from 5 to 45°C. This variable resistor is activated by ...
AutoPilot's user avatar
0 votes
1 answer
122 views

Unresolved Issue in MOSFETs-based Variable Load Circuit Design and Simulation

I've been diligently working on designing a variable load for the purpose of testing both AC and DC power supplies. For this task, I have opted for the integration of back-to-back MOSFETs in the ...
Cinar Reis's user avatar
4 votes
3 answers
138 views

Can a buck converter provide a lower voltage based on a target differential - instead of an absolute target?

I have an application where I need to provide a lower voltage from a starting voltage. In other words - I need a buck converter. My question is - if I have a known required differential but a ...
Daniel Miller's user avatar
1 vote
1 answer
893 views

Declare a PIC pin in a variable [closed]

So basically, I want to store a pin of a PIC MCU inside of a variable. eg. int pin = LATB5 I also need to pass that pin to a function. If I do it like this, it ...
leo6002's user avatar
  • 25
0 votes
1 answer
66 views

Circuit design help for automating fan from another device

I'm trying to design an automation for the status/current setting of my one electrical motor (1-6 variable settings) to drive a few behaviors to another motor or possibly two. The electronic devices ...
No-Reservations's user avatar
1 vote
1 answer
267 views

Determine the min/max resistance of an SMD variable resistor

I want to determine my minimum and maximum resistance rating for my variable resistor but failed to find the relevant information in the datasheet (this might be an issue more 'noobs' might have, ...
user2305193's user avatar
3 votes
1 answer
233 views

Confusion with variable update in microcontroller programming

I use an STM32 microcontroller board and to summarize the question, in the following code inside the if clause the variable called ...
user1245's user avatar
  • 4,333
0 votes
2 answers
394 views

Same variables and different values on instances

I have searched on google but I have not found a way to put different values in the variables of the same symbol placed more than once. Each component "X11, X12..." etc, are the same, and ...
Jose de la Rosa's user avatar
0 votes
2 answers
142 views

How can I make this variable power supply go from 1.25V and -1.25V to 0?

I'm trying to learn and in this case I have a power supply circuit that has a fixed 5V, a 1.25 to 12V and a -12V to -1.25. I understand that the regulators I'm using have a minimum limit output of 1....
wmorales76's user avatar
1 vote
1 answer
487 views

Mimic a thermistor/variable resistance signal using PWM

I am looking for a way to create a variable resistance signal to mimic the signal that would typically be provided by a thermistor, but by using a digital signal that switches to ground. I currently ...
CSla's user avatar
  • 11
0 votes
1 answer
123 views

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 ...
user7858768's user avatar
0 votes
1 answer
108 views

Basic Variable Loundess Audio Amplifier

I am a beginner, looking to make an extremely basic variable loudness (gain) audio amplifier. I have a general idea of how a class A amplifier works, but I am not sure how to make one variable. This ...
mihkelr's user avatar
0 votes
1 answer
66 views

Solid state data?

I'm wondering if there is a way to store a small integer in a way that if you turn the microcontroller (an atmega328, in my case) off, and then turn it back on again, the variable won't reset. Do I ...
e3rowning's user avatar
0 votes
1 answer
124 views

Can you replicate a Trimpot with a 555 timer?

I'm currently a senior ME major and just entered the EE world to complete project so I'm a little lost. I am building a circuit powered by an Arduino Mega Chip. The circuit is to control ...
Cuddisaveslives's user avatar
2 votes
1 answer
3k views

Variables in LT Spice Value

Is it possible to add a variable into the value of a component in LT spice? I'd like to simulate a resistor divider to look at current consumption but keep the ratio of the resistances the same. I ...
Pete's user avatar
  • 155
0 votes
1 answer
290 views

Reading the schematic diagram of a power pack [closed]

We've purchased a bit old type of a power pack. It's got DC voltage manual reading bar and DC ampere manual reading bar. Assuming that it can measure the current while allowing to give a specific ...
AliceX's user avatar
  • 13
0 votes
2 answers
3k views

How to declare a global variable in Verilog

Say I have module_A , module_B and module_C and a variable as “reg[3:0] x”. I want all three modules A,B and C have access to read and modify variable x ( something like global variables ). Is it ...
Aug's user avatar
  • 1,581
0 votes
0 answers
696 views

PWM controlled variable resistor

I need to have variable resistor (from around 5kOhm to 100kOhm range). The problem is that this "resistor" see 350V (rectified 230V mains). The control signal is PWM and need to be isolated ...
eSlavko's user avatar
  • 171
0 votes
1 answer
466 views

Resistor and potentiometer values to obtain 1.25-12V variable with an LM317

I want to make a variable power supply up to 12V. For that I want to select resistor and adjust potentiometer values. I have calculated below values from this website.https://circuitdigest.com/...
usmandroid's user avatar
-1 votes
1 answer
239 views

Switch on/off connection between variable voltage source and load

I am trying to switch on/off the connection between a load and a variable power supply (going from -10 to 10 V) using a combination of NMOSFETs and PMOSFETs. I want to use MOSFETs because of limited ...
Tungstein's user avatar
0 votes
1 answer
68 views

Do I need a current protection?

I have a variable gain amplifier that can output a current of 90 mA. The output is directly connected to a µController I/O pin. My question is: do I need something like over-current protection, since ...
Yoomo's user avatar
  • 363
0 votes
1 answer
531 views

RTC with ATmega32 and DS1307 showing the year completely wrong

I'm building a clock/calendar with an ATmega, a DS1307, and a 20*4 LCD (LM044L). I have implemented the code showing the time correctly, I have initialized the RTC too, but for some reason when I try ...
Hitman2847's user avatar
0 votes
1 answer
318 views

Convert a voltage from 0-12V into a resistance from 0-264 ohm

I have a fuel sender that works on 12V and sends the reading to the engine. The engine wont start with it disconnected (hence the diode). What I need is to copy the resistance of the fuel sender using ...
hughebeling's user avatar
0 votes
1 answer
136 views

Designing a circuit that outputs variable voltage

Total noob here, I'm looking to implement a circuit to control a fan that has these specifications: Pin 1 and 3 are DC- Pin 2 is DC+ Voltage should be from 6 to 16 V It needs to operate in 70-second ...
aelveon's user avatar
0 votes
1 answer
59 views

Does anyone have experience with the recom rpx-1.0 or similar that could explain a few things to me?

I'm looking to have 4 dc-dc converters each with different outputs but one voltage input value. Vout of 9V 12V 15V and 18V. Would this chip be able to do that? Here is a bit from the data sheet and I ...
DRC's user avatar
  • 107
2 votes
4 answers
459 views

Using a potentiometer to control greater resistance

This is more a theoretical question: Let's say we use a potentiometer as a variable resistor. We can set it from 0% (0Ω) to 100% (let's say 1Ω for simplicity). Using this pot we can reduce the total ...
flawr's user avatar
  • 721
0 votes
2 answers
268 views

Model train incandescent (wheat grain) bulb to LED

I watched and was inspired by the following video. Add Directional Lighting to a Bachmann BIG Hauler using Diodes and 1.5V Grain of Wheat Bulbs I have a Bachmann 49 Santa Fe locomotive. It's older yet ...
Twisty's user avatar
  • 101
0 votes
1 answer
179 views

Unsigned int values gives negative number above the halfway point of max byte value?

MCU: Atemga328P: Datasheet:https://ww1.microchip.com/downloads/en/DeviceDoc/Atmel-7810-Automotive-Microcontrollers-ATmega328P_Datasheet.pdf Note: I am a beginner :) Considering a 2 byte ...
user13174343's user avatar
1 vote
1 answer
767 views

Variable band-pass filter for splitting audio signal into separate signals (high and low freqs)

I've been wondering for quite some time how to create a sort of audio splitter. The idea is to get an audio signal (e.g. guitar) at the input, and have two separate outputs, one with the input's low ...
Piotr Sławęcki's user avatar
0 votes
0 answers
322 views

Convert Hair Dryer to Variable Speed

I am using a hair dryer to increase oxygen/air levels in a torch assembly for a forge for metal work. I need to be able to increase/decrease the fan motor speed smoothly and more precisely than the ...
Ian G's user avatar
  • 101
1 vote
0 answers
635 views

How to calculate values for my variable DC power supply

I am making a variable DC power supply via Multisim and the values are given to me is V1=7, V2=15, Imax(load)=209mA (both V1 and V2 is DC value which is on U1.) I am using resistors, an LM317 voltage ...
Sabretooth 2438's user avatar
0 votes
1 answer
705 views

Vary Capacitance in LTSpice

I would like to model a condenser microphone in LTSpice. This kind of microphone has a variable capacitance dependent on the incoming pressure. I know how to vary a resistor with time, but ...
omnom cashews's user avatar
1 vote
1 answer
878 views

MOSFET in place of potentiometer

Since in potentiometer we control it by rotate its knob anticlock wise or clock wise...so in that place i want to control it by using MOSFET and Arduino means the working of the knob i want to control ...
Jacob's user avatar
  • 17
4 votes
3 answers
689 views

Is this a variable resistor?

I acquired a lot of vintage electronic components at an estate sale. The sale included a dozen of what may be variable resistors. These components are all the same size and have the same plastic ...
Roger's user avatar
  • 41
1 vote
1 answer
108 views

Replace fixed to variable potentiometer on DC regulator

I recently bought a DC regulator (power supply and tester.) It is a 15V and 2A power supply with voltage fixed to 1.5V, 3.6V, 4.8V, 6.0V, 7.2V direct output of the sub-grade and the current is ...
Tengku Rahmaddansyah's user avatar
1 vote
1 answer
490 views

Variable speed control of a DC motor

I have a Leeson 3/4 HP motor available to me, which I want to turn a pulley on my lathe and control voltage via a Penta KB Power KBWM-120. I am a little lost on how best to do this or if I have the ...
DanPersson's user avatar
0 votes
1 answer
124 views

In need for high variable capacitance

I am constructing a Chebishev or Butterworth audio filter (low and high pass), but I need to have all parameters highly adjustable - especially Fo and Q. For this purpose i would need to be able to ...
IreMaster's user avatar
2 votes
1 answer
2k views

Variable-Gap Capacitors in LTSpice

I have seen several blog posts that discuss the concept of a nonlinear capacitor (or inductor) here, here, and here. Thanks to a concerned citizen for the references. I'm still struggling with the ...
drumdude92's user avatar
1 vote
2 answers
565 views

Variable resistors - resistance value meaning

I'm normally using in my circuit board a 10K variable resistor. Those specific 10k variable resistors are no longer in my supplier stock for now and I was wondering if I can place a 200k variable ...
Mehdi's user avatar
  • 33
2 votes
3 answers
542 views

Is there such a thing as an automatic variable resistor

I have a skid steer loader that in ISO (for example, driving straight forward) with one joystick supplies on average 50 milliamps more power to the right forward solenoid coil than to the left coil ...
Steve's user avatar
  • 21