# All Questions

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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 ...
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?
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 ...
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.
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 "...
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 ...
7k views

Are there any special requirements for charging lead-acid batteries?
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?
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 ...
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 ...
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 ...
22k views

### How to integrate a signal in LTSpice?

Is it possible to integrate a signal in LTSpice and plot the result?
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....
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 ...
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 ...
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 ...
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 ...
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?
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 ...
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 ...
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 ...
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 ...
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 ...
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? ...
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 ...
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?
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 ...
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 ...
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.
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 ...
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.
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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: $$C=B \cdot log_2(1 + S/N)\text{ bits/sec}$$ ...
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 ...
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, ...
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?
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 ...
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?
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 ...
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 ...
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 ...
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 ...
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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