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Questions tagged [variable]

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11
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2answers
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 ...
1
vote
0answers
19 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 ...
0
votes
0answers
64 views

Handling Large Variable Data with a Microcontroller

What is good practice for storing and manipulating variable data in a microcontroller circuit when the data may exceed microcontroller working memory? In my application, I am designing an access ...
0
votes
2answers
35 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
votes
3answers
219 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 ...
0
votes
0answers
79 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....
0
votes
2answers
83 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 ...
1
vote
2answers
39 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
votes
1answer
37 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 ...
4
votes
1answer
282 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
votes
1answer
66 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 ...
0
votes
2answers
91 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 ...
2
votes
2answers
78 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 ...
6
votes
3answers
128 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 ...
0
votes
1answer
244 views

LTSPICE - Changing parameters of a pulsed voltage source

At the moment I'm simulating a basic buck converter circuit and would like to be able to vary the duty cycle given to the circuit by a microcontroller (switching a MOSFET). I'm simulating the micro ...
1
vote
1answer
170 views

Controlling a Piston Variable Pump with a Raspberry Pi

I'm involved in a team that is controlling an AA10VG axial piston variable pump using a Raspberry Pi 3 Model B V1.2. I've been delegated to design the circuit which will control the pump's ...
12
votes
2answers
2k views

What is 'unsigned char near'?

I read a datasheet and I found variable defined as unsigned char near Sample_X. What is this, and how does this differ from ...
0
votes
1answer
28 views

Transforming from abc reference frame to the qd0 variable reference frame?

I have been working on transforming variables from the abc reference frame to different qd0 frames of reference, such as the stationary reference frame, the synchronous reference frame, and the ...
1
vote
1answer
86 views

PIC12F629 variables overflowing with nested loops

I'm trying to do a simple binary counter using a PIC12F629 (Code below), driving LED's direct from GPIO pins 0,1,2. I'm sure it should be a very simple counter, but as written it just won't count ...
1
vote
1answer
83 views

Altium - Do Schematic Variables Exists?

In Altium Designer (v.16.0), I would like to assign several resistors with the value "R", and being able to change them only by assigning the value of R to e.g. 10k, at some place of the application. ...
0
votes
0answers
23 views

Question regarding an Op-Amp substitution [duplicate]

This schematic has a LM107 op-amp at its heart. It seems that it is now discontinued. Will a uA741 op-amp be a good substitute? If not, why not? What would be a good substitute? Thanks.
-2
votes
2answers
76 views

Power/current limitations of variable gain amplifier

I am working with a motor invention and I am wondering about the utility of variable gain amplifiers. I wonder how to achieve a high output current with such an amplifier¿
-3
votes
1answer
64 views

Running electronics bought in USA in the Uk? [closed]

Ive got this power supply for a nintendo switch that was purchased in USA that i want to run in the UK. On the back of the power supply (see image below) is says 100-240v. Apart from using a plug ...
-1
votes
1answer
295 views

5 ma to 2 amp variable current circuit using TIP120 BJT. Please analyze my circuit and comment

I'm trying to build a circuit that can output current from 5ma to 2Amps using BJT TIP120. Voltage is 18v and constant. I tried designing a simple circuit. Please check the image below and let me ...
3
votes
1answer
217 views

12V variable-speed fan as a function of temperature using 555 timer

I would like to turn the car fan into a variable-speed fan using a the analog temperature sensor of the car, and a 555 timer. While temperature decreases, resistance (of the sensor) increases. Can I ...
1
vote
1answer
324 views

STM32 HAL CAN does not update value and crashes when setting ExtId

I'm running my first CAN test program using STM32CubeMX, STM32F103C8T6 and Eclipse. I used default CAN settings in STM32CubeMX (also tried loopback but the results are equal). What I see (see pic ...
0
votes
0answers
43 views

Variable differential amplifier

I made this scheme: simulate this circuit – Schematic created using CircuitLab Gain of this differential amplifier is constant and equal to 2. I would like to have possibility to substract ...
2
votes
3answers
779 views

Why do I get a compiler warning with “int __attribute__((address(0x3000))) x;”

I am trying to understand why I get the following warning ...
9
votes
4answers
735 views

Voltage Regulated by Resistor in Generator Circuit

So I am tinkering with making a circuit that will allow a motor to generate power to charge a battery. I have this, what I presumed to be an, AC induction motor I salvaged from an old Christmas ...
0
votes
1answer
446 views

fly back diode for use with DC motors

I asked a question the other day but am still unsure, I just bought a 0-30v 0-5A dc regulated power supply today and want to use it to play around with various DC motors, I was told I didn't need to ...
0
votes
1answer
170 views

12v DC Motor with variable power suipply

Im looking at buying a 0-30V 0-5A variable regulated power supply to play around with dc motors ranging from 3v to 12v and varying amps. I plan to connect them directly without using mosfets, ...
0
votes
2answers
117 views

Can power of an electromagnet be changed like frequency of a motor is changed using VFD?

I am from a commerce background and am not technical. I want to use an electromagnet to lift up Iron and Steel but since I have a retail shop, I have to lift up varying quantity as per the demands of ...
0
votes
2answers
340 views

Installation of an AC Drive on a Plastic Extruder

We operate a Plastic Extruder for reprocessing plastic waste. The Extruder is powered by a 40hp 1,440rpm AC Motor. Motor Pulley: 8" Machine Pulley: 16" Gearbox's Gear Ratio: 14:1 Currently, the ...
0
votes
0answers
193 views

unstable magnetometer readings

I did the magnetic calibration here on the LSM303DLHC for a field roughly 48 uT. The method seems to have worked in that the combined bias (b) values went from ...
3
votes
3answers
1k views

Precise Current Limiting for Variable 0–300VDC Supply

I wish to use this circuit to achieve a variable 0–300V DC supply. However, I'm interested in keeping the current below 50 mA, with as little variance from that value as I can achieve without doing ...
2
votes
2answers
2k views

Safe 0–300 VDC variable supply

I want to make a 0–300V variable DC power supply (max current 100 mA). I found this design, which features a 1:1 transformer across the mains for some sort of safety reasons. However, I couldn't ...
2
votes
2answers
199 views

Interpreting this ADC circuit

I am trying to read from the SGX MICS-6814 gas sensor. The documentation has 2 small sections on how to read the output: From the datasheet: From the FAQ document To start with they show the ...
0
votes
1answer
44 views

Science project: second variable

I'm a completely new to electronic circuits and such and am currently learning to pull of this project where I'll be testing how temperature affects a battery's life. Testing using a camera on time ...
5
votes
5answers
7k views

where are constant variables stored in microcontroller?

As per the memory layout of C program ,constant variables are stored in the Initialized data segment of the RAM. But as per some of the Microcontroller memory layout ,const variables are stored in ...
0
votes
1answer
39 views

Variable does not bounce back as desired (LED's)

I am changing a variable with a predetermined rate. When my variable gets too large, I cap it back to the largest value I want to make it, and change the sign on the rate to make the change go the ...
2
votes
1answer
73 views

Installation of an AC Drive on a Mixer - Help

We have a 30hp 1440rpm AC motor installed on a mixer. Motor Pulley: 6" Machine Pulley: 20" According to my calculations, the mixer runs at 432rpm. Operating Procedure: The mixer is loaded with ...
2
votes
1answer
2k views

Why does Modelsim say that VHDL shared variables must be protected?

So I created a shared variable in a purely non-synthesizeable code. When compiling ModelSim generates a warning: (vcom-1236) Shared variables must be of a protected type. Why is it a warning and ...
1
vote
1answer
576 views

Determining wattage of a variable resistor in series with a known resistor

I'm trying to determine the wattage of a variable resistor Rvar which will be wired in series with a 2 ohm resistor Rs as in the above figure. Rs can handle high currents. The power supply V1 is 24V ...
0
votes
3answers
221 views

Splitting voltage and current unevenly

I want to make my lab variable power supply from an old laptop power adapter (19V 6A) with an LCD to show Volts and Amps. The LCD needs an independent powersupply. Can I make a circuit to give me the ...
0
votes
1answer
477 views

Altium PCB dimensions

I am looking for a way to automatically update the PCB dimensions in my PCB documentation. I have the X & Y dimensions listed in the title block as PCB strings. They are currently set as project ...
0
votes
1answer
114 views

Output range for switch mode regulator

I'm using LM2576 regulator for having variable DC voltage. The output of the regulator specified in the datasheet is 1.23v to 37v. I need voltage to vary between 0v to 10v. I found that using a charge ...
0
votes
4answers
4k views

Can I make a one-speed AC motor variable-speed by modulating the power input?

simulate this circuit – Schematic created using CircuitLab I'm using a Raspberry Pi with a SainSmart solid-state relay. If I connect the relay to an AC motor (a box fan in this case) and run ...
5
votes
2answers
3k views

How to save variables inside microcontrollers memory

I am designing an application which include GSM SIM900 with PIC18F2520. The application includes basic calling and sms services. ...
1
vote
1answer
258 views

“General Purpose” Current Limiter?

So i have been trying for a few weeks to create a current limiter that fills my needs but i have failed/i don't even know if it's possible. Basically i want to make a current limiter that can work ...
2
votes
2answers
360 views

Simple variable Capacitor circuit to feed ADC

I need to build a humidity sensing circuit that feeds an analogue to digital converter. (This converter is then going to send its signals to a raspberry pi for analysis etc). The sensor will be about ...