# Questions tagged [basic]

Fundamentals of electricity, electronics, components, or theory

371 questions
323 views

### Wire 5 vibration motors on one switch

I am trying to run five vibration motors rated at 3.7 volts each on one switch. The power will come from a 12V, 40 Amp relay on my Jeep (SPOD). How can I wire the motors all together to turn on at one ...
133 views

### Why is diode D2 affected by the current of Vin and the choice of R1?

I was wondering why D2 will not always forward voltage drop .6 volts? Ground is at 0. What happens if R1 is incorrectly chosen? Could too much current through D1 push back on D2 and prevent flow ...
167 views

### Is the “antenna aperture” the same as the “hole in the shield”?

Is the concept of the "Antenna Aperture" the same as a hole in a electromagnetic shield? The wikipedia article is quite vague, and I am a newbie in this field. For example if we have an electric ...
147 views

### Basic Capacitor Question To help Cement My Foundation Properly (LTSpice)

I have the following circuit in LTSPice. I can see +- 3.5 uA of current at various nodes. I should be able to calculate the 3.5 uA given the R and the C. I note that the sim output is sinusoidal. ...
380 views

### Ultra-basic question: where is the voltage in this simple circuit diagram?

I'm trying to understand the role of pull-up resistors, and keep coming across this basic circuit diagram illustrating the "floating" condition. I'm struggling to understand how the switch at S1 ...
964 views

### Input voltage/current required for LM1117 3.3 Power Regulator

Can I use Mobile charger having Output Rating of Voltage 6.0V / Current 300mA as input to LM1117 3.3 Chip. If possible - Will it be able to provide 800mA current when required and how?
114 views

### New to EE classes, have an introductory voltage output problem

sorry if this seems very easy but I am looking for a little help as I have only just begun to learn EE. My homework problem has me create a power supply using a common reference point only a 24 V ...
1k views

196 views

### Help me solve this TAOE problem

So, I picked up this book and am working through it by myself. I am a bit stuck on problem 1.6: In the bottom you can see how I'm approaching this. I'm assuming the transmission cable goes across NY, ...
1k views

### Is a load needed to measure the voltage drop of a long cable?

Should be a simple yes or no question. If I attach 20ft of 16AWG cable to a power supply, in theory I should see some voltage drop. Do I need to place a load at the end of the cable to read the ...
1k views

### why electricity requires a closed loop to flow?

Imagine a battery with the positive terminal connected to ground. The positive side has a high eletrical potential, ground obviously has a lower electric potential. Electricity wants to seek a lower ...
398 views

### Understanding an N-JFET

I am currently learning about FET transistors, and there is some things that I do not understand about an n-type JFET. I have two question about this transistor. Why is Vgs important and how do we ...
159 views

### In a real-world op-amp, how does it make sure Vn and Vp differs and don't equal each other?

I was confused about op-amps and asked this question: In an op-amp, why does Vn approach Vp until the difference is delta V / A? Why doesn't Vn just equal Vp? and received really helpful answers. ...
1k views

### In an op-amp, why does Vn approach Vp until the difference is delta V / A? Why doesn't Vn just equal Vp?

In an op-amp (non-inverting), when $V_s$ increases by $\Delta V$, $V_n$ approaches $V_p$ until the difference is $\Delta V/ A$ (where A is infinity). Why is there the $\Delta V/ A$ ...
94 views

### Measure currents (~50 mA) at every 10 microseconds interval and store the data [closed]

I'd like to measure the current across a tiny load (current range is maximum 50 mA) at every 10 microseconds, and store these values for later reference to plot a Current vs Time graph. Is it possible ...
1k views

### Audio amplifier schematic explanation

I'm repairing an old amplifier Sansui A-40 which I got from a friend. Here's a portion of the original schematic: What does the red marked area do, and how does it work? I'm not familiar with that ...
826 views

### Relationship between voltage/current & LED strips?

I recently bought a WS2812 LED strip (5 meters, 300 LEDs) When the LEDs are driven at full brightness and each color lit, they draw 60mA each--or 18 amps for all 300! This led to a problem, which ...
80 views

### Help me understand dielectrics

So, they're insulators or poor/non-conductors of electricity. Yet somehow they are also capable of holding and/or transmitting an electrical charge. Does that not seem like a crazy paradox, ...
1k views

### Good analogy for watts vs amps?

According to plumbing analogy I've hard time seeing why power is measured in volts*amps, instead of just amps. I found an analogy from http://science.howstuffworks.com/environmental/energy/...
933 views

### High power IR transmitter circuit for ESP8266

Currently I am using this IR transmitter circuit for an ESP8266: It works, the reception is not bad, but I need a little bit higher power to control my AC unit. The AC unit is ca. 10 meter away from ...
92 views

### when a capacitors is being charging from a battery is battery discharging?

I'm studying yet. Is a battery discharging when capacitor connected to it is charging? Please explain how does it work!
447 views

### Calculating the dropper / series resistor for an LED [duplicate]

I'm so sorry if this is a stupid question. I have read some of the questions previously asked but in afraid the maths and physics are way over my head. I have made a wooden template and would like it ...
95 views

### Is it possible to control distance of RF Transmitter

Noob question here, is it possible to control the distance range of RF transmitter. I need a RF transmitter application where i can control its distance with pot.
438 views

### Understanding voltage and current - is there voltage without current flow?

I'm trying to increase my knowledge of electric circuits and their major components. My current understanding is very basic, which will explain why my question may seem laughable to most people on ...
419 views

### adapting 60 LED battery operated string-light to work with wall wart

I need to adapt one of these 60 LED string-lights to be powered through a wall plug. These are micro LEDs all wired in parallel; sadly, I couldn't find specs for this kind of LED. The string's power ...
405 views

### Current flow with a Diode [duplicate]

I'm just starting out learning about Electronics but something has puzzled me . I have read that current flows through a circuit from negative part of a battery to positive . but what puzzles me is ...
112 views

### What is this torus wire coil next to dc motor?

I'm currently playing with a cheap \$7 RC car from the toy store, and has just started out with arduino and electronics. What is the purpose of the torus thingy with wire going around it, between the ...
150 views

### What is the correct way to read color codes? [duplicate]

For example, The resistor above has four colors. Green, blue, red, gold. My calculation says its value is 562 ohms +-10%. But this page says its value is 5.6K-1/4W. What is my mistake?
2k views

### Why is an infinitely large capacitor a DC open circuit?

This really sounds like a stupid question, but I believe it's worth asking: Due to $I=C\frac{dU}{dt}$, and $C$ is infinitely large, any minor change in $U$ would result in infinite current,...
191 views

### Why resonant charging produce “no current immediately after discharge”?

It's me again, still reading AoE 3rd. On page 40, footnote 35, the author writes: Resonant charging is used for the high-voltage supply in flashlamps and stroboscopes, with the advantages of (a) ....
2k views

### “A zener with series diode”?

So I'm still reading The Art of Electronics Third Edition. On P.39, when dealing with indicative "kick", I found this sentence: For the fastest decay with a given maximum voltage, a zener with ...
697 views

### What does an “ac coupled signal” mean?

I've heard this term many times from many different sources, but none of them gave me a definition. Here is my understanding: "coupled" means "connected together". If two circuits are "capacitively ...
501 views

### Large capacitors “producing more I²R heating”?

On page 35 of The art of Electronics Third Edition, when describing the disadvantages of reducing ripple by choosing large capacitors, the author writes: The very short interval of current flow ...
151 views

### The Art of Electronics exercise 1.19 [duplicate]

I'm reading The Art of Electronics(3rd), and I'm just stuck with exercise 1.19. Here is the question: Explain why L∝n² for an inductor consisting of a coil of n turns of wire, maintaining fixed ...
130 views

### Unable to make a pot work correctly

I have a board I salvaged from a joystick that uses potentiometers to measure the location of the arms. On the PCB a edge pin and the center pin are wired together. I would like to connect the pots to ...