Questions tagged [design]
The process of creating electronic products, including components and end-user devices.
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questions
56
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What's this importance of datasheets?
As someone starting with electronics I keep hearing, "Check the datasheet!"
Why are datasheets so important and what information can I expect to find in them? It seems like a large amount of ...
16
votes
5
answers
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What is metastability?
From the Wikipedia article Metastability in electronics:
Metastability in electronics is the
ability of a digital electronic system
to persist for an unbounded time in an
unstable equilibrium ...
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107
votes
6
answers
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Ceramic caps vs electrolytic. What are the tangible differences in use?
A quick google around and all I seem to be able to find are people talking about the physics & the chemistry of the capacitors but not how this affects choosing which to use.
Avoiding talking ...
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0
votes
1
answer
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Designing an Oscillator
I'm tired of having to resort to Google to find every single oscillator design. I would usually just try to search for a circuit using the same frequency crystal, and try to build that.
Right now, I ...
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votes
15
answers
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What are low cost circuit and PCB design software? [closed]
Do you know of any freeware or low cost circuit / PCB design software?
I know a few which I have listed below but I was wondering if there were more of its kind. Please mention the good features and ...
- 1,339
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votes
7
answers
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Internal or external oscillator
I always use the internal oscillator that pics have as I have never found the need to run anything at higher frequency than 8 MHz (which is the fastest the pics I use tend to be able to go). Are there ...
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vote
3
answers
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BJT Amplifier with Emitter Bypass Capacitor Design [closed]
I am trying to design a BJT amplifier. The circuit is shown below with its parameters.
beta=180
RL=20kΩ
VA=0 (early effect can be ignored)
VCC=15V
There are three constraints listed below:
Swing ...
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57
votes
5
answers
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Stripboard/veroboard/matrix board design software
I'm prototyping a simple layout for a small project on matrix board, but figured there must be a better way than drawing it all out on paper. Are there any aimed at matrix board?
I've found the ...
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votes
10
answers
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Circuit Simulation Software [closed]
I'm getting back into hobbyist electronics after a very long hiatus and was wondering what the current state of circuit simulation software is. What is the industry standard for macs or PCs? What are ...
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votes
5
answers
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Why does active low even exist?
In my career I've often encountered signals that are active low (Reset being the most common). I've even seen interfaces where all control signals are actively low.
To me, this is very unintuitive ...
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4
answers
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At what level of complexity should I consider UL listing my widget?
I am interested in making a widget to sell, but it will probably have a small market and small volume. At what level of complexity should I consider UL listing (or otherwise certifying) my widget?
I ...
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3
answers
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How to implement a soft power switch controllable by microcontroller?
I want to design a circuit such that the microcontroller can toggle a GPIO pin and shut the whole system (including microcontroller itself) down. And when the user presses a momentary button, the ...
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5
votes
3
answers
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Maintaining a constant current with varying loads
I've designed a constant current source using a current mirror, we need an output of about 50mA. The problem is that we build it and heat has become a problem.The transistors and the R_load are both ...
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4
votes
2
answers
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The flyback diode and its applications
So in an application like this:
The coil of the motor will, by Lenz's Law, induce a very large negative voltage across its terminals (without the diode in place). Would this voltage be very negative ...
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4
votes
3
answers
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BJT Bias Design and Operating
I'm to the task to design a BJT Common-Emitter Amplifier with resistance at the emitter as in the figure, and for that I need to:
get the values for \$R_{1}\$, \$R_{2}\$, \$R_{C}\$ and \$R_{E}\$
...
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54
votes
3
answers
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How to go from a development board to a production board?
Ok, I am a software guy and new to electronics. My product needs a small computer and currently I have developed everything on development boards like raspberry pi and such. As the development board ...
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31
votes
11
answers
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What is the most amazing PCB artwork you've ever seen?
Have you ever looked at a PCB and burst out laughing?
Have you ever looked at a PCB and said "Wow, that is amazing"?
Have you ever seen a PCB that artistically expressed criticism of society's ...
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3
answers
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What are FIT's and how they used in reliability calculations?
In Military, Medical, Space, Professional eqt. design there is a need to be able to prove that your device can last a certain length of time with a certain confidence level. Or that reliability must ...
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5
answers
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Learning about electronics
I'm a computer scientist with zero exposure to things directly related to hardware (barring what I learned from my undergrad computer org class.)
I've been very attracted to the field of embedded ...
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4
votes
2
answers
1k
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Transistor design with beta variation
I am studying Schilling-Belove Electronic Circuits, 3rd Ed. where in its second chapter under the "Maximum Symmetrical Swing" section it gives an example where the base current is kept constant and ...
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votes
4
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Construct an 8k X 32 ROM using 2k X 8 ROM chips
Construct an 8k X 32 ROM using 2k X 8 ROM chips and any additional
required components.
Show how the address and data lines of the constructed 8k X 32 ROM are
connected to the 2k X 8 chips.
I ...
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1
vote
4
answers
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Is it possible to build an H-Bridge with only N-MOSFETs (and these other components)?
I am trying to design an H-bridge circuit and I am only given the following components:
Opamp
Zener Diode
Resistor
Capacitor
N-MOSFET
NPN BJT
Diode
2-input NOR
2-input NAND
Infra-red Detector
Infra-...
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1
vote
1
answer
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When an NMOS utilizes a PMOS current source load, which transistor is acting as the current source?
Referring to the following schematic:
My current understanding dictates that a transistor will output a certain drain current given an input voltage at the gate (V1 and V2). How can this behavior ...
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vote
3
answers
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Frequency Detection Circuit Design
I want to create a circuit that can detect audio frequencies and flash RGB LEDs different colors depending on the detected frequency. The frequency range will be from 20 Hz to 12 kHz, after looking at ...
- 1,244
0
votes
4
answers
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Automatic switch using LDR
I've implemented above circuit and it was successful.
The given circuit needs 12VDC to run properly.
I want to run this circuit on 5-6VDC or 9VDC whichever is possible. I know I have to change ...
- 5
28
votes
10
answers
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How do I power/wire something that is rotating constantly WITHOUT extra batteries?
So I want to make a Lazy Susan that is rotating constantly in one direction. I also want to have some other things on top such as neon signs, moving things, and etc. Problem is I want this to all run ...
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26
votes
5
answers
6k
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Making a battery last a long time in a microcontroller circuit
I'm hoping to power an ATtiny85V for a nice long time on some small battery, probably a coin cell.
I've looked into the software side, and my code is watchdog timer driven, has unused analog and ...
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20
votes
2
answers
4k
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Industry Practices for Schematic Design?
As my designs (and PCB designs too) become more complicated, I'm interested if there are best practices or industry standards for schematic design. I know there's a schematic checklist but I'm looking ...
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votes
4
answers
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analog circuit design resource recommendations [closed]
What are some excellent resources related to advanced analog circuit design? This includes RF, sonar, audio, low-frequency, high power, low power, noise, amplifiers, etc.. To get the most obvious ...
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votes
5
answers
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What are the best free schematic tools out there? [duplicate]
I'm sure there are plenty of schematic tools available. Which ones do you use/prefer?
Feel free to also list tools which aren't completely free but very popular.
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votes
3
answers
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Getting started with PCB designing
I'm a hobbyist EE in college, and have been building breadboard circuits and perfboard circuits for the past year or so. I want to move on to doing PCB design.
I wanted to start with something small ...
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6
answers
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Why do we want gap in the core material while designing inductor?
In some cases it is necessary that core of inductor should have a gap, unlike with transformer core. I understand the reason with the voltage transformer core; there is nothing to worry about core ...
- 13.8k
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votes
1
answer
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What are these spots on the PCB that are by the mounting holes?
When you look at the board, there is a weird part of the PCB right of the top left mounting hole. There is also another one above the top right mounting hole.
****...
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votes
2
answers
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Driving a LED from a wide ranging input voltage
I have been working on a small linear power supply, capable of regulated output between 2V to 30V, using the LM338 IC. For the most part it is a simple implementation taken straight from the datasheet....
user31299
8
votes
2
answers
3k
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In a 74HC14 Schmitt trigger IC, unused inputs/outpus
I have a 74HC14 Schmitt trigger IC. I only use one of its I/O pairs, and everything else is not used.
I understand that in TTL logic the unused inputs should be set to either high or low to prevent ...
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votes
2
answers
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What's a reference text on analog design?
I'm looking for a intermediate text that covers (discrete) amplifier circuit theory using BJTs and FETs and circuit elements such as current mirrors, differential stages, feedback theory, etc. My ...
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votes
4
answers
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Why is designed active low?
I buy a 2 channel relay module for Arduino.
I surprised that why this relay module is designed active low?
Circuit:
i means that when we connect In1 to low V (GND) relay turn on. Is there any reason ...
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6
votes
2
answers
7k
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Beginner information related to constant current dummy loads
I am beginning an electronics design project to build a constant current load to drive testings for batteries, bench power supplies etc. I have been hard trying to locate some black-on-white ...
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votes
1
answer
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MOSFET H-bridge design
given the circuit below to be used as a H-bridge with AVR PWM.
Is this a good desing to use? What can you recommend?
I already built something like this but without the resistors. ( and so burned ...
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4
votes
2
answers
756
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Symmetric power sockets – design considerations in electrical devices
There are various single-phase power socket standards in use. Some countries use plugs that can be plugged in the socket only in a specific orientation (for example, the United Kingdom) while other ...
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votes
1
answer
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Altium de-highlighting nets after using 'Find Similar Objects...' command
I can't work out why Altium is doing this, or how to undo it, or how to make it stop doing it.
It happens when I use the 'Find Similar Objects... ' option; all of objects that it hasn't found are ...
- 1,285
3
votes
3
answers
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Electronically switched decade resistance box design
I'd like to design a decade resistance box that uses a microcontroller to control the resistance.
Would it be possible to switch between different valued resistors using transistors? (or another ...
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votes
3
answers
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How to test and rate a home-built low dropout regulator?
I built a low dropout regulator following experiences building a discrete linear regulator. The circuit is simple like this:
simulate this circuit – Schematic created using CircuitLab
I would ...
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3
votes
1
answer
10k
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Serial Adder vhdl design
I've a design problem in VHDL with a serial adder.
The block diagram is taken from a book.
Since i'm not skilled enough in design with clock (except some silly flip flop i've found on the web, and ...
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2
votes
1
answer
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Design a 3-to-8 Decoder Using Only Three 2-to-4 Decoders
Using only three 2-to-4 decoders with enable and no other additional gates, implement a 3-to-8 decoder with enable. The inputs of the resulting 3-to-8 decoder should be labeled X[2..0] for the code ...
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votes
2
answers
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What is a minimum load?
If the minimum load of a sensor(page 7) is 65k Ohm, what does that mean?
Does it mean that the sensor needs at least a 65k Ohm resistor, so a 100K Ohm is good?
Or does it mean the sensor needs at ...
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votes
1
answer
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ICs that convert an AC signal into its true rms value
I need to convert the instantaneous voltage output from my current transducer to a true RMS voltage output. Can anybody please suggest an IC that can perform this function.
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votes
1
answer
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Wireless water level sensor, in sump. Installation best-practices for longivity
My wireless water-level sensor is working fine, and when deployed in the sump-well, it is giving me periodic readings quite well. At this stage, I have the circuit still on a breadboard, and now plan ...
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3
answers
10k
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Square Wave Amplifier - 5VDC -> 13VDC
I want to have a square wave that goes from 0 VDC to 5VDC go through some sort of amplifier and that amplification takes that same wave ( at a frequency of 1200Hz but could also be adjusted later ) ...
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vote
4
answers
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How to measure the component value on a PCB?
I have faced a few instances in which I need to measure resistor or capacitor value which is soldered to the PCB board (SMD component). These are very small and difficult to look the value written on ...
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