Questions tagged [variable]

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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 ...
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2 answers
89 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....
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1 vote
1 answer
54 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 ...
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1 answer
60 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 ...
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1 answer
75 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 ...
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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 ...
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1 answer
95 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 ...
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2 votes
1 answer
199 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 ...
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1 answer
99 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 ...
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2 answers
563 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 ...
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197 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 ...
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1 answer
126 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/...
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1 answer
68 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 ...
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1 answer
61 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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1 answer
138 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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1 answer
92 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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0 votes
1 answer
60 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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1 answer
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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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2 answers
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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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1 answer
93 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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0 votes
1 answer
254 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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0 answers
95 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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1 vote
0 answers
122 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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0 votes
1 answer
208 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 ...
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1 vote
1 answer
366 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 ...
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4 votes
3 answers
664 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 ...
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1 vote
1 answer
53 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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1 vote
1 answer
88 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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0 votes
1 answer
70 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 ...
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2 votes
1 answer
785 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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1 vote
2 answers
120 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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2 votes
3 answers
360 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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1 vote
0 answers
30 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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0 votes
1 answer
191 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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-1 votes
1 answer
52 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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0 votes
1 answer
207 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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0 votes
3 answers
724 views

Cannot fine tune Colpitts oscillator with crystal

I'm trying to design a cheap video synthesizer. In order to do it, I need to provide my Arduino Nano with an external clock so it can drive the timer that generates the complex video pulses I need. ...
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-3 votes
2 answers
130 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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0 votes
4 answers
621 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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0 votes
2 answers
161 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 ...
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4 votes
2 answers
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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0 votes
1 answer
41 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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0 votes
3 answers
109 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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-1 votes
2 answers
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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2 answers
152 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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2 votes
2 answers
892 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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1 vote
2 answers
193 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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1 vote
1 answer
143 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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2 votes
2 answers
238 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 ...
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11 votes
3 answers
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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