Questions tagged [variable]
The variable tag has no usage guidance.
124
questions
0
votes
1
answer
55
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. ...
- 153
0
votes
1
answer
86
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 ...
0
votes
0
answers
38
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 ...
- 153
0
votes
0
answers
38
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 ...
- 1
0
votes
4
answers
292
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 ...
0
votes
1
answer
100
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 ...
- 87
4
votes
3
answers
119
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 ...
- 141
1
vote
1
answer
541
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 ...
- 25
0
votes
1
answer
57
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 ...
1
vote
1
answer
161
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, ...
- 309
3
votes
1
answer
192
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 ...
- 3,994
0
votes
2
answers
257
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 ...
0
votes
2
answers
131
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....
1
vote
1
answer
338
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 ...
- 11
0
votes
1
answer
98
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 ...
- 101
0
votes
1
answer
95
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 ...
- 3
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 ...
- 37
0
votes
1
answer
114
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 ...
2
votes
1
answer
2k
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 ...
- 135
0
votes
1
answer
219
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 ...
- 13
0
votes
2
answers
2k
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 ...
- 1,561
0
votes
0
answers
590
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 ...
- 171
0
votes
1
answer
397
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/...
- 67
0
votes
1
answer
184
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 ...
- 47
0
votes
1
answer
64
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 ...
- 353
0
votes
1
answer
418
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 ...
- 113
0
votes
1
answer
209
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 ...
0
votes
1
answer
99
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 ...
- 3
0
votes
1
answer
47
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 ...
- 107
2
votes
4
answers
348
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 ...
- 681
0
votes
2
answers
217
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 ...
- 101
0
votes
1
answer
175
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 ...
- 439
1
vote
1
answer
587
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 ...
0
votes
0
answers
237
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 ...
- 101
1
vote
0
answers
456
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 ...
- 129
0
votes
1
answer
557
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
vote
1
answer
728
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 ...
- 17
4
votes
3
answers
685
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 ...
- 41
1
vote
1
answer
95
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 ...
1
vote
1
answer
330
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 ...
- 45
0
votes
1
answer
94
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
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 ...
- 73
1
vote
2
answers
394
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 ...
- 33
2
votes
3
answers
446
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 ...
- 21
1
vote
0
answers
31
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.
- 11
0
votes
1
answer
364
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 ...
-1
votes
1
answer
81
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.
- 1
1
vote
1
answer
596
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. ...
0
votes
3
answers
1k
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.
...
- 21
-3
votes
2
answers
143
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 = ...
