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51
votes
6answers
24k views

Does pulsing an LED at higher current yield greater apparent brightness?

This question implies two assumptions: The frequency of a switched LED driver is high enough that average power, not instantaneous power, should be used to determine maximum drive current. The ...
37
votes
3answers
68k views

What's a schematic (compared to other diagrams)?

What's the difference between a schematic, a block diagram, a wiring diagram and a PCB layout? Why do engineers want a schematic instead of a wiring diagram? Where does Fritzing fit into this?
24
votes
7answers
54k views

How to clean my soldering iron tip or how to determine that it's beyond repair?

First, I've read though questions Soldering Iron Maintenance and Going through Soldering tips quickly and was unable to solve my problem. I have recently (as in less then a month ago) obtained ...
26
votes
6answers
27k views

Does this photodiode circuit work?

Oli used this circuit in an answer, and it pops up a lot on Google images too. But does it work? If it does a theoretical explanation will be welcome.
14
votes
4answers
22k views

Thermistor control of peltier voltage with Arduino (for DSLR chill box project)

I am mildly familiar with electronics, mostly from playing around with electronics kits as a kid. That was a long time ago, though, maybe as much as 20 years ago. I am currently working on a cold or "...
13
votes
14answers
26k views

Why are the power transmission/distribution systems AC and not DC?

Is there a good reason why we are not in the process of completely converting our electrical transmission system to DC? The main reason for using AC on the grid (no offense Tesla, I love you man) was ...
27
votes
5answers
7k views

Charging lead-acid batteries?

Are there any special requirements for charging lead-acid batteries?
6
votes
3answers
10k views

Structure of a usb 2.0 connector [duplicate]

What is the role of the outer metal connector? (the one with two square holes) Does it have a potential? Is it insulated from the 4 pins? Are the 4 pins insulated from each other?
17
votes
2answers
14k views

Calculate battery life

I would like to know how to calculate battery life when using an LED strip. The LED strip is powered by 8 AA batteries in series. LED Current Draw = 260 mA. LED power consumption: 3.1 W. LED Operating ...
13
votes
3answers
14k views

Driving DC motors with MOSFETs and a microcontroller?

I'm developing a nano quadcopter using an Atmega328 microcontroller, powered at 3.3V, and very small brushed DC motors. The average current used by these motors is about 800mA @ 3.7V. Initially, to ...
22
votes
2answers
5k views

Why are many IR receivers in metal cages?

I'm guessing it's a Faraday cage around the receiver, but don't know why they might need one. Is there some sort of common interference around 38kHz (their operating frequency)? It's the only ...
4
votes
4answers
22k views

How to integrate a signal in LTSpice?

Is it possible to integrate a signal in LTSpice and plot the result?
10
votes
6answers
49k views

Charging Li-ion batteries in parallel

I wanted some opinion on my set up here, just to make sure I got the basics right. I have a Li-ion battery charging circuit based on the MCP73113. This is designed to be a single-cell battery charger....
7
votes
5answers
18k views

Which way to draw diode in a circuit diagram

Im having a bit of trouble drawing a circuit with a diode in. I know the current flows from negative to positive, but convention says that current goes from positive to negative. When drawing a ...
6
votes
3answers
20k views

Bootstrap circuit function

I had some question about the bootstrap capacitor on gate driver. First, the bootstrap capacitor is used because the voltage on the high side drivers gate need to be about 10-15 volts higher than the ...
15
votes
5answers
12k views

Was Benjamin Franklin wrong (about conventional current)?

I am starting to see a lot of people claiming that convential current is 'wrong' because Franklin made an error when he first started investigating electrostatics, and that later scientists didn't ...
8
votes
1answer
814 views

Can I use blue-green LEDs as MCU state indicators on 3.3 V power?

Modern electronics industry has developed very efficient LEDs with nice and fancy colors (“true green” , “cyan”, and “blue”) based in InGaN technology, or similar. Some of these LEDs are specified as ...
8
votes
3answers
678 views

Name of component on output side cable of a DC power adapter?

What is the name of this component (circled in red) of a charger? What are the uses of this component?
3
votes
3answers
7k views

How does this Push-Pull amplifier work?

I'm reading about op-amp circuits that use negative feedback from this article (question no.19). What confuses me is that the negative feedback for the Op-amp (which is being used to reduce ...
81
votes
6answers
78k views

What type of solder is safest for home (hobbyist) use?

I'd like to do some hobbyist soldering at home, and would like to make sure I don't poison those living with me (especially small children). Lead-free seems necessary - what other features should I ...
61
votes
9answers
264k views

Difference between latch and flip-flop?

What is the difference between a latch and a flip-flop? What I am thinking is that a latch is equivalent to a flip-flop since it is used to store bits and is also equivalent to a register which is ...
35
votes
6answers
14k views

Designing a *linear* MOSFET driver stage

I'm looking for a MOSFET driver circuit that can be placed between an op-amp and a power MOSFET to operate the transistor as a linear amplifier (as opposed to a switch). Background I'm developing an ...
70
votes
6answers
38k views

What is Copper Thieving and why use it?

On many boards I've seen, there are little copper dots used for the purpose of "Copper Thieving". They're small round copper dots connected to nothing and arranged in an array. Supposedly they're for ...
49
votes
9answers
39k views

Is a current-limiting resistor required for LEDs if the forward voltage and supply voltage are equal?

For blue LEDs with a forward voltage of 3.3 V and supply voltage of 3.3 V, is a series resistor still needed to limit current? Ohm's Law in this case says 0 Ω, but is this correct in practice? ...
33
votes
5answers
11k views

Should I really divide the ground plane into analog and digital parts?

I am about to design my first PCB as part of my graduation project. Of course, as the first step, I try to learn as much as possible. A part of the research I found this 3 part article, that suggests ...
29
votes
5answers
42k views

How are logic gates created electronically?

So we have AND, NOT, NAND, NOR, OR gates, but how are they created electronically/electrically? For example, what makes NOT gate reverse the value?
43
votes
8answers
10k views

Why isn't there a potential difference across a disconnected diode?

I know this question sounds silly, as if there was a potential difference a current would be created when the terminals are connected together and this would mean energy has come from somewhere. The ...
33
votes
3answers
15k views

How can I detect a power outage with a microcontroller?

I have the following power supply configuration: AC MAINS -> UPS -> 24V POWER SUPPLY -> 5V VOLTAGE REGULATOR -> PCB (microcontroller). What's the best solution to detect the power outage on the mains ...
64
votes
9answers
24k views

When to avoid using a breadboard

What are the cases where one should avoid using a breadboard? e.g. high frequency, noise prone circuits etc.
34
votes
4answers
48k views

Safe current limit for human contact?

What's the point below which electrical current is generally considered safe for "casual" human contact? Is either voltage or amperage more "dangerous" (e.g. high voltage / low amperage vs. low ...
27
votes
6answers
359k views

How to Calculate the time of Charging and Discharging of battery?

How do I calculate the approximated time for the Charging and Discharging of the battery? Is there any equation available for the purpose? If yes, then please provide me.
19
votes
4answers
4k views

Current sensing nA to mA

I need to sense the current of a target MCU through various periods of its on/sleep/off state and then need to send this data back to another interface MCU to read out the value. They will be both on ...
18
votes
6answers
32k views

How to read high voltages on microcontroller?

I want to read high voltages, like ~50V, using a microcontroller. I plan to put this as an input into the microcontroller's A/D line. But of course, you shouldn't have voltage that high on the input ...
21
votes
3answers
87k views

What are the ways to make a dual power supply from a single voltage source?

I have a function generator IC XR2206 from EXAR. It's application circuits uses dual power supply +/-9 volts. How can I make such a 9-0-9 dual supply from a single voltage source like a battery or an ...
17
votes
3answers
12k views

Can a Zener diode that protects a switch against inductance when the switch opens, affect turn on speed of the valve when you close it again?

As you probably know, in the applications that the turn off speed of the solenoid valves are crucial, the simple flyback diode is not effective. Some people put a resistor in series with the flyback ...
34
votes
2answers
10k views

Schottky transistor, Not sure I understand it?

So I've been looking through and going through my Digital Computer Electronics book, and I came to this... It seems so simple and I understand the "point" of it, but I'm not sure I understand exactly ...
34
votes
7answers
24k views

Debouncing buttons

I recently read an article about button debouncing and was wondering if I should keep this in mind when working with, for example, an Arduino (ATMega mC)? I assume it is an issue, especially when ...
22
votes
3answers
31k views

DC biasing audio signal

I have seen a few different ways of adding DC bias to an audio signal. I have simulated them and they all give me similar results, but I can't figure out why choose A over B or C. My audio source will ...
45
votes
5answers
48k views

Is the neutral wire considered safe?

If the neutral wire carries current, why do many people believe that it's safe? I've heard "You can touch the neutral wire/bar in the breaker box and not get shocked. Only the hot can hurt you." If ...
12
votes
2answers
6k views

Why is channel capacity a factor of bandwidth instead of frequency?

I'm trying to understand the concept of capacity for a wireless channel. Some help would be appreciated. For a AWGN channel capacity is calculated as: $$C=B \cdot log_2(1 + S/N)\text{ bits/sec}$$ ...
23
votes
6answers
19k views

What are the highest DC and AC voltages or currents that can be considered as safe?

By safe I mean safe for us when we touch a wire that is not insulated. I have heard that human body resistance is normally 50k Ohm when dry and 20K Ohm when wet. Therefore, these voltages or currents ...
13
votes
4answers
65k views

Why does a delta/wye transformer make 30 degrees phase shift ?

I'v heard that a delta/delta or Wye/Wye transformers do not make any phase shift. In delta/wye or wye/delta transformers, There is a 30 degrees phase shift between the primary and secondary coils. So, ...
14
votes
3answers
108k views

MOSFET as a switch?

In the picture shown, can "Output" be controlled to be 0V or 12V based on "Control"? Will be Drain and Source the way it is connected be a problem?
14
votes
1answer
5k views

'Voltage Fuse' or better

I have a power supply with multiple outputs (5v, 12, 24v) According to the manufacture (and after testing) there must be a minimum load on the PSU for it to supply the stated voltages. Without a ...
53
votes
3answers
35k views

What does 3V3 or 1V8 mean?

While reading a datasheet for an IC I came across the pin voltages being presented as 3V3 or 1V8. What does this representation stand for?
12
votes
5answers
6k views

"Overclocking" an AVR

In AVR datasheets under the Electrical Characteristics section you will typically find a graph like this (this one is from the ATMega328): I've seen designs that seem to "work" but operate outside ...
2
votes
3answers
2k views

Colpitts oscillator's capacitors

I've been reading more about how oscillators work and one of the more simple ones is the Colpitts oscillator. My understanding is that two capacitors in combination with the inductor can produce ...
9
votes
2answers
4k views

Logic level converter using Transistors

I am trying to make a logic level converter using transistor BC547. This is to convert Voltage level of Rpi Gpio from 3.3 to 5V. I have wired the circuit according to this diagram: I have done this ...
8
votes
1answer
2k views

Simulation model for floating gate

I am designing a non-volatile memory cell and foundry does not have model for floating gate . So I used the Voltage controlled current source to mimic floating gate. For output characteristics, I ...
6
votes
2answers
22k views

555 timer, one shot trigger

I'm trying to create a circuit that will pass a 12V pulse on the rising edge of a push button (it can be triggered by the entire input pulse but rising edge preffered). I've had some experience with ...

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