Voltage, otherwise known as electrical potential difference (denoted ∆V and measured in volts) is the difference in electric potential between two points (adapted from Wikipedia). Voltage can be constant (DC) or varying (AC).
0
votes
2answers
22 views
Connect different devices (Ground/Voltage mismatch)
To begin with, I realize that voltage is relative but I do not get how to get a common ground so that everything is relatively correct to go in and out of the chips.
The picture summarizes the setup:
...
4
votes
1answer
73 views
How could extension cord detection be implemented in Tesla Roadster?
Googling finds evidence that Tesla Roadster electric car can detect cases when it is plugged in via extension cord.
Specifically this page lists error codes 937 and 9 meaning "extension cord ...
-8
votes
0answers
54 views
Crystal oscillator “voltage control” pin usage [closed]
What does "voltage control" mean for a crystal oscillator?
For example where a crystal oscillator marked "40 Mhz" has a control pin.
Can I use PWM to control it?
-6
votes
1answer
37 views
Voltage/resistors/series/impedance/meter
Assume you measure a power supply voltage through a series 1M OHM resistor and observe that is drops by 1/2 its former value when no resistor is in series. What is the input impedance of the meter? ...
1
vote
2answers
68 views
Voltage Controlled Attenuator
I'm trying to create a DC voltage attenuator which linearly scales the loss relative to an applied control voltage "Vc". In other words, K = Vout/Vin is a linear function of Vc. Vin is guaranteed to ...
2
votes
0answers
37 views
Built-in voltage [duplicate]
Hello all I have work on the following question and just wondering if you all could check to see if i did it correctly.
The built-in voltage of a GaAs pn junction diode is 1.25 V when the diode's ...
5
votes
1answer
71 views
Doping concentration in anode region
I'm stuck with this doping problem and can't figure out where to go with it.
The built-in voltage of a GaAs pn junction diode is 1.25 V when the diode's temperature is T = 320K. The cathode ...
0
votes
1answer
94 views
What voltage is put across the Tx+, Tx-, Rx+, and Rx- lines over ethernet?
I'm trying to figure out how to wire up an LED, probably controlled by a FET, for an activity indicator for ethernet. I'm not trying to make one that supports official error codes or anything, but ...
4
votes
1answer
106 views
How to build a voltage-controlled current sink / voltage-controlled resistor
I am trying to control a current through several current-mirror device (specifically the IREF pin on the TLC5940) using a single potentiometer. I've tried using a ...
0
votes
2answers
177 views
basic math question about voltage, ohms, resistance
total n00b here. After working on several projects by copy & paste from other people's schematics and code, I'm finally digging in and learning some of the math to know what I'm doing.
If I have ...
0
votes
0answers
72 views
Compliance question
Q. You have +5 and +15 volt regulated supplies available in a circuit. Design a 5mA npn circuit source(sink) using the +5 volts on the base. What is the output compliance?
This is what I've done:
...
2
votes
2answers
59 views
Problem on output compliance?
What is exactly meant by output compliance of a current source? I've read that it's the range of voltage over which the current source behaves well. What exactly does behaving well mean?
I've got ...
-3
votes
0answers
37 views
Induced Voltage Problem Between Cables [closed]
In our application we have varied low voltage cables and there are some medium voltage and high voltage cables belongs to external system.
Some of our cables have metallic shield and some have not.
...
0
votes
2answers
71 views
Warm voltage regulator [closed]
Why is my voltage regulator get warm while my car is not running "68 corvette" battery is also going dead, is it the regulator or another problem?
-1
votes
2answers
119 views
threshold problem on a Schmitt trigger op amp
I have the Schmitt trigger op amp on the below diagram. (channel A & B refers the oscilloscope probes on the following figures).
The resistor values are selected to set the trigger threshold as ...
2
votes
4answers
117 views
Voltage Converter's GND Problem
I am confused about the ground part of a voltage converter.
This is a typical voltage converter. As you can see the the main voltage is 230V, and the output is 5V. Look at the output 0V, which is ...
2
votes
2answers
101 views
Wireless transmission of energy through a layer of non-conductive material
Is it possible to effectively transmit energy by electromagnetical induction?
I have a plate of nonconductive material (5-10 mm) and I would like to transfer electrical energy from circuit on one side ...
2
votes
1answer
66 views
transistor loop to limit the current
I am trying to implement the DALI TX/RX circuit below.
The description says:
The other transistor (T2) is controlled by the current flowing through the
resistor (R1). If a DALI slave unit is ...
-5
votes
0answers
62 views
If e=300sin157t, how long (in sec) does it take this waveform to complete 1/2 cycle? [closed]
This was the problem given to us. The way I am looking at it is that I need to solve for t (time). My question is that wouldn't I need to know e before I can solve it? What am I missing?
0
votes
2answers
71 views
Get current wattage from an electronics plugged in
Firstly, I'm not really an electrician or an electrical guy with lots of knowledge about electronics but I'm always interested learning to it.
Yesterday, I asked my wife to help me out determining ...
2
votes
1answer
64 views
Octopus Component Tester Analysis
I'm a beginner in electronics and my knowledge is pretty basic. I've been trying to understand how the Octopus Component Tester Works. I know that it's outputs should be used to plot a Current x ...
0
votes
1answer
85 views
TLP280-4 Optocoupler on 12/24V inputs
There is a STM32 device which has to detect several signals from other devices. The voltage of these signals can be 12V or 24V. Also these signals can be positive (i.e. 12/24V) or negative (connected ...
1
vote
1answer
69 views
connection from an comparator to an optocoupler
I have the circuit below to decode a signal that is defined as Logic high >9.5 V and Logic low <6 V
To determine the ...
0
votes
2answers
122 views
DC-DC Voltage Doubler
I am an amateur, but i'd like to know if this circuit would work to double a 0-30 volt DC input to a 2-60 volt DC output. If so, what kind of CAPS and DIODES do i need to support this? I need to Power ...
0
votes
1answer
45 views
Motor Driver, increase output voltage
I have a sabertooth motor controller and it is rated max 33v input. I need (at max) almost double that on the output. Can I hook up one of these to the output port, between the sabertooth and the ...
1
vote
1answer
74 views
Voltage drop from poor connection
In a DC circuit, why does an open circuit voltage drop appear across a bad connection?
For example i have 48vdc wires where a connector is charred from bouncing/bad contact. Under no load the side of ...
4
votes
2answers
117 views
Have I fried my Arduino UNO?
So I've recently been playing with my first Arduino, until it, for some weird reason, stopped working.
What I did:
I had it attached to a breadboard. When I say attached, I mean it was supplying ...
1
vote
0answers
42 views
Effect of 30% voltage variation on life of tubular heat elements
In my country voltage variation can be up to 30%. Recently we had many commercial foodwarmers fail in the same locations while another brand of similiar equipment works perfectly.
The manufacturer of ...
8
votes
2answers
132 views
Compensating the forward voltage drop of a diode signal rectifier
I am reading Arts of Electronics and they are showing this circuit:
It says that D1 compensates for D2's forward drop by providing 0.6V of bias. I don't understand this circuit at all. Is the +5V ...
1
vote
2answers
72 views
Correct AMPS & volts for DC motor controller
I'm definitely an amateur hobbyist, but I need to fix something for a friend.
I have a existing DC motor and the controller is shot. The motor is rated at 0-90 VDC (5Amps)
I wanted to see if this ...
0
votes
1answer
79 views
How does a multimeter convert voltage/current to a numerical value?
Just wondering... How does a digital multimeter work ? How can it convert a voltage, a current or a resistance to a numerical value ? I guess there is some programmable chip inside, but how does this ...
5
votes
2answers
87 views
Similar LED, higher voltage drop, less bright
I was measuring voltages in my circuit, and noticed something strange.
I have an array of 8 LEDs. Each of them is in series with a 220 Ohms resistor. The circuit has a 5v source.
simulate this ...
0
votes
1answer
58 views
Increasing the Voltage Output of a Solar Cell
I'm working on a project where I'm going to charge a battery using a solar cell. The cell is capable of outputting a maximum of 4 A, but only 0.5 volts (2W).
My question is, how can I charge the ...
1
vote
1answer
54 views
Cable thickness for solar borehole pump
I have a solar borehole pump: 24 volts - 270 watts panels (two x 135W). I want to move my panels 300 to 350 meters away from the borehole, reducing the risk of theft. What size of cable should I use ...
2
votes
2answers
125 views
Why do batteries in series add up voltage?
This question will probably sound easy to most of you, but to me, it is still a kind of magic :)
Taking in account all I know until know, I guess a battery has two sides:
one that "emits" electrons ...
3
votes
2answers
148 views
Vacuum cleaner power rating does not match line voltage and current rating
I have a vacuum cleaner on which is proudly written:
12.0 Amps
1300 W
Assuming a 120 V (RMS) power supply, how would the power consumption of the vacuum cleaner be calculated given the 12.0 ...
3
votes
3answers
198 views
Oscilloscope noise reduction when measuring IC voltage
I am trying to monitor the voltage of an IC. The supply voltage of the IC is 3.3V and clock frequency is 24MHz.
Here are some parameters for the channel used for measuring voltage:
vertical scale to ...
1
vote
2answers
81 views
Mosfet Circuits Voltage
So let's take a simple cmos circuit like this:
So I get that for DC analysis \$V_G = 12 \frac{R_2}{R_1+R_2} \$ and then \$ V_{GS} \$ makes sense to me...because there is a constant \$ V_G \$ value ...
4
votes
3answers
109 views
Under what conditions should we use negative voltage? [duplicate]
As mentioned in the title I'm curious and confused under what circumstances a negative voltage should be used? Does it mean in a negative voltage power supply the current is flowing from ground point ...
0
votes
4answers
120 views
How can I make LED's light up equally?
I have built a Binary to Unary (kind of) circuit on my breadboard.
It looks like this:
simulate this circuit – Schematic created using CircuitLab
There are three switches that ...
0
votes
1answer
122 views
How do you convert a signal that is either -5 or +5V to 0 or +5V, respectively
In my circuit I convert a 0 or 5V signal to a -5 or 5V signal using a schmitt trigger to get some hysteresis. However, I'd like to convert the signal back into a 0 or 5V. In effect, I'd like my ...
-5
votes
0answers
51 views
Measuring voltage change between two separate circuits [closed]
Is it possible to measure a voltage produced from one circuit in another which is powered by a different cell / power source.
To give a simple example, is it possible to have a potential divider on ...
-6
votes
0answers
48 views
Taking baby monitor to Europe [closed]
I am taking my baby monitors to Europe. They work with a df 6 volt 110 adapter. Can I switch the adapter to a dc 6 volt 110-240 and add a European plug to use them safely there or do I absolutely need ...
1
vote
1answer
39 views
Get Vm using Vrms
This is bit of a noob question, but here it goes.
There is a circuit whose input is Vm*sin(wt) and a Vrms of 240V at a freq of 50hz
To get Vm do I just multiply Vrms by sqrt(2)?
Thanks
2
votes
3answers
140 views
Calculate expected voltage around a resistor [duplicate]
It's been a few years since I first studied the Ohm's law at school.
Now I'm really getting into electronics, and I must admit a part of it still puzzles me.
I know this is kind of a strange ...
-6
votes
1answer
121 views
Transfering 1 bit on Ethernet [closed]
Why is the voltage for transfering 1 bit on Ethernet so low when the capacity for transmitting electricity is so high in copper wire
-1
votes
2answers
102 views
How do I calculate the voltage needed to heat up a wire to a certain temperature?
The wire I am using is standard temp. nitinol wire which needs to be heated up to 45 degrees Celsius in order to be effective (move). What voltage do I need to achieve this?
1
vote
1answer
138 views
How to amplify 3.3 volts to 8-9v?
I'm a total newbe in electronics but I like to make things up. All I want is to turn on a "black box" of leds (that operates at 8-9v) when my motion sensor is activated. The problem I've got is that ...
-2
votes
3answers
84 views
Converting voltage to amperage [closed]
I was wondering if power transformers can be used to convert a high-volt/low-amp AC to low-volt/high-amp AC.
For example:
AC power input (E±=100 I=1) to a transformer primary (100 windings) and ...
1
vote
1answer
112 views
Keeping the output of a heated LM317 constant
I have built a power supply using an LM317:
simulate this circuit – Schematic created using CircuitLab
When the supply is on for a rather long time (several hours) with a respectable ...
