Questions tagged [variable]

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1answer
54 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 ...
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1answer
49 views

RTC with ATmega 32 & ds1307 showing the year completely wrong

I have this project to build a clock / calendar with ATmega and ds1307 showing it on a 20*4 LCD (LM044L). I have implemented the code showing the time correctly, i have initialized the RTC too, but ...
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21 views

How to determine the variation in Q point given some resistor tolerances

In Microelectronics 4ed (Neamen), in page 157 Ex 3.8 they ask to find how Id and Vd would vary acording to some variation in the resistors. They don't explain how to do this in the book so i thought ...
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1answer
73 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 ...
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1answer
52 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 ...
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1answer
27 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 ...
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2answers
86 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 ...
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1answer
49 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 ...
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1answer
70 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 ...
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0answers
64 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 ...
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0answers
93 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 ...
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1answer
76 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 ...
1
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1answer
170 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 ...
4
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3answers
648 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 ...
1
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1answer
42 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 ...
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1answer
63 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 ...
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1answer
66 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 ...
2
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1answer
353 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 ...
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2answers
67 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 ...
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2answers
239 views

Is there such a thing as an automatic variable resistor

I have a skid steer loader that in ISO eg driving straight forward with one joystick supplies on average 50 milliamps more power to the right forward solenoid coil than to the left coil causing the ...
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0answers
29 views

a Variable rehostate servo Motor to discharge a Tesla S model battery

Anyone could help me to find a Variable rehostate with servo Motor to modify load on a high power system. I am trying to discharge a Tesla S model battery.
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1answer
107 views

LM2596S-ADJ Buck Converter Circuit heating up and wasting a lot of voltage somewhere

I've built my own DIY adjustable buck converter using a teensy, a gate driver and all manner of components. It worked ok (I was able to vary voltage from 20 mV all the way up to about 20 V when my ...
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1answer
48 views

Want to vary speed on 12 volt DC RV ceiling fan

I have a 700 cm 12 volt DC RV ceiling fan that can work using my 12 volt DC solar power system. I want to figure out a way to vary the speed of the fan.
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1answer
66 views

Designing a triac based regulatable DC supply

I need about (30V-160V)32A DC for my project. I am trying to build an electronic circuit to regulate AC mains (220V, 50Hz) to produce voltage from 30V to 160V and rectify it to produce DC voltage. ...
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2answers
301 views

Can not fine tune Colpitts oscillator with crystal

I'm trying to design a cheap Video Synth. In order to do it, I need to provide my Arduino Nano with some external clock so it can drive the Timer that generates the complex video pulses I need. What ...
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2answers
114 views

Do I need a “full differential” ADC? (if sensor voltage input range = 0.8V to 4.3V)

I am not using potentiometer like most video or print online. I am using bike grip/hall throttle, its range is 0.8V to 4.3V. Instead of: [0V = 000 ADC value] [5V = 255 ADC value] I want: [0.8V = ...
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4answers
408 views

Adding to the output of a DC/DC Boost Converter using the same power supply as the input?

I've got a project that requires a variable output between 24-48V. This needs to be continuous-current, not PWM. Items that I have handy from my 'box of bits', and ready to work with are: an 0.6-36V ...
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2answers
101 views

Hard Reset variable change in MCU

I have an activation system with a unique password per activation operation. If the system goes down or is not working correctly and I need to reset it to a operational state I could design a hard ...
1
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1answer
2k views

Variable field magnet motor?

See the video in the following link: https://www.youtube.com/watch?v=olnXy-J48SY "Variable field magnet motor" How does this work and is it actually efficient?
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1answer
40 views

Regulated Low voltage signal creator

I am trying to mimick a sensor on a car that supplies 0.7 V to the car’s computer. So what I would like is a circuit diagram to build a unit that would use the 11 to 14 V input from the car battery ...
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3answers
106 views

Is it possilbe to make up some sort of circuit that would allow you to vary the Ah provided by a battery?

I suspect the answer to this question - "Is it possible to make up some sort of circuit that would allow you to vary the Ah provided by a battery?" - is "NO, Not Possible" but here goes. I want to ...
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2answers
58 views

How to know if the load is variable one? [closed]

For example, I have an air conditioner. How to know if such a device has a variable load or not ? NOTE: Air conditioner is just an example. My question is in general how to know ?
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2answers
119 views

Need help identifying and finding similar SMD variable resistor

The component appears to be damaged, but the datasheet for the board in question shows that this is a 47k ohm variable resistor. Looks like a trimmer, but not 100% sure. However, I've been trying to ...
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2answers
473 views

JFET Vgs Calculation Equation

Does anyone know the formula to calculate the Vgs of a JFET used as a variable resistor? Say, I have a Vds of 24v and I require a current of 20mA (just arbitrary values) I would need a 1.2k resistance,...
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2answers
116 views

Assigning a 16 bit number to two bytes of a buffer [closed]

Currently I have this out buffer that I am assigning values to like this: ...
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1answer
129 views

How come PC/laptop power suppliers have much higher wattages per physical size than laboratory switching power suppliers?

This 2.2 kg 1000W BeQuiet BN213 ATX power supply is able to provide 12V 83A (no typo. Eighty-three.), which is around 1000 W. This huge PS900W (60V15A 30V30A 15V60A) bench power supply weighs 5 kg ...
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2answers
191 views

Persistent RAM variables in NIOS II

I would like to define a C variable in RAM which can survive a CPU reset in NIOS II IDE. Something like __persistent in PIC world or ...
11
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3answers
1k views

Variable declaration with @ in C

I am reading some C code and came across this declaration in the program: unsigned char serv_ctr @0x0002; Can someone point me to documentation, or explain what ...
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0answers
210 views

HFSS - Replacing a variable with a new variable

I want to put two similar designs in a single design. Both designs share some common variables with different values. When I put them together in a single design the common variables share same values ...
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2answers
190 views

Variable Current Amplifier for Fan Control

I'm working on a project where I need to vary the current supplied to a DC fan. I am currently trying to use a BJT as a current amplifier to amplify a low current analog output (0 to 100 mA to vary ...
2
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3answers
300 views

How can I change step-down my variable input voltage?

Ok so here's the deal: I have a variable DC Voltage source from 0-10V. I need to step that down to a variable source of 0-3V. This 0-3V DC will be fed to an Analog to Digital converter in a ...
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0answers
88 views

Voltage controlled voltage regulator?

I have a voltage that's used to dim a 12V bulb and I'd like to use it to dim an LED instead. My plan so far is to use a triangle generator and a comparator to make a PWM signal with varying duty cycle....
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2answers
123 views

Is there such thing as a Laser beam detector that returns a non binary result?

As the title implies , i'm looking for a device that can detect at what point a laser beam has been broken. So idea would be the device to output a certain voltage depending on where someone's finger ...
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2answers
123 views

How to represent a variable DC supply potential difference on a circuit diagram

I have a circuit diagram for a physics experiment. On the diagram I have represented a variable DC supply, but I would like to know where do I write the potential difference selected on the variable ...
0
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1answer
49 views

Will a large variable power supply burn out a heating element?

I'm currently learning about electronics so I bought myself a variable power supply - something I think will be useful over the coming years. I would like to know if I use a hot wire cutter (most ...
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1answer
991 views

High voltage variable capacitor design

I’m building a homemade small magnetic transmitting loop antenna that I want to ultimately operate at up to 1500 watts over the HF ham radio bands. One of the challenges with these antennas is the ...
0
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1answer
213 views

+-10v variable power supply

I need to generate a variable voltage ranging from +10v to -10v in order to control a motor driver. What are ways to generate this voltage? To clarify: the motor driver takes +-10V as an input. +10V ...
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2answers
416 views

Variable voltage switching 12vdc

I am looking for a circuit that would be switching a relay coil and few small leds (max 3A) with a low voltage input. Now the input is variable voltage 1.1v to 5v produced by a hall sensor pot. I want ...
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2answers
223 views

MPLAB X XC32 - Peculiar build issue involving volatile variables

I am struggling with an issue that is already costing me 2 days of productive work. The code of main.c at the end of the question is a stripped-down version of the entire project, and contains the ...
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3answers
234 views

Design of a switchable dual voltage power supply

My project would benefit from power supply with two modes selected by a switch. The 'normal' mode is full voltage (±13.5V) at full current (~5A), the 'high' mode is double voltage (±27V) at half ...