The process of creating electronic products, including components and end-user devices.

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1answer
46 views

AC power cord different on a laptop and a desktop, other appliances

If I look at the power cord plugged from the wall socket to desktop computers, monitors, etc. at the office, it looks like (North America): Now, if I look at the power cord plugged into my laptop's ...
0
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3answers
51 views

Convert Electret Microphone output to digital data for transmition

I might be asking a stupid question but.... I was wondering about whether or not there is a circuit to convert the output of an electret microphone to 1s and 0s for transmission. And then we can use ...
0
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1answer
44 views

Making a magnetic levitation system with arduino

I am planning on making a magnetic levitation system with an arduino that checks the value of a hall's effect sensor twice per second (but I have tried even 1000 times a second though) and turns the ...
0
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3answers
73 views

10A/115V Jumper

What component would you use for a 10A/115V jumper header (I need the user to be able to choose among a few power settings)? I have relatively small space on the PCB and I am also trying to be ...
0
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1answer
28 views

Single motor + Timer. Lift and reverse hand. Single joint robot arm

I need help trying to design a single jointed robot arm that will lift to almost flat on a wall, back down to a right angle position on a timed sequence, repeatedly. It would pause for a few seconds ...
1
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1answer
54 views

Need help designing headphone amplifier circuit

I have to design a headphone amplifier circuit. We are told the impedance of the headphones and the minimum voltage they require and also the voltage source. After researching I have found that the ...
1
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1answer
68 views

Textbook for learning analog IC design? [closed]

I am currently using Carusone's "Analog Integrated circuit design", but this book seems more suited as a reference book for professionals who already know the subject. Are there any good alternatives ...
1
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1answer
31 views

FT230XS USB Bridge not working

I designed a small board that needed the capability of communicating over USART, so I threw in an FT230XS USB|USART Bridge. The device use is so simple that I am out of ideas for troubleshooting. ...
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0answers
39 views

multi stage digital design

while design a NOR3A ie a 3 input nor with A input inverted. we have two ways build a two stage nor3A OR build a 3 stage and3BC(apply demorgans to NOR3A ) so while computing the delays i found that 3 ...
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1answer
55 views

Capacitor grounded between 2 resistors

This is part of a segment of a design I came up with using schmitt triggers as relaxation oscillators. The picture below shows the 4 possible states of the circuit at any given time. Basically, the ...
3
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2answers
333 views

What is the meaning (definition) of “current-starving”?

In several circuit descriptions we can find the term „current-starved“, „current-starving“ or „voltage-starved“. Example In chapter 4 (Current-starved voltage-controlled oscillator) we can read: ...
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1answer
74 views

Can the LD1117V33 handle short peaks of up to 900mA?

Got a project with the typical 5V and 3.3V power requirements. My initial prototype I used the LM3940 (datasheet). This worked pretty well but these regulators are damned expensive here in Australia ...
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2answers
104 views

Help in the design of a super low power device

I'm building a wireless device that have to last with batteries as long as posible. The device has an rf module with a microncontroller that manages the control, that part is bought and works fine. ...
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4answers
181 views

How To Hold Power ON For Some Time Without Using A Microcontroller or 555?

This is my first question here, so I'm hoping for help. I'd like to take a Momentary event and use it to turn on a device (LED, for starters to model the concept) for a minute (give or take) at a ...
-2
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0answers
35 views

Frequency presence to light up LED

Can anyone provide a simple circuit schematic that uses an antenna to detect the presence of a specific frequency and in response lights up an LED. I have been doing some reading on resonant (LC) ...
2
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0answers
60 views

Specified frequency signal detector

I understand that band pass filters are used in some circuits to filter out the desired frequencies. I also understand that an antenna picks up radio waves in the air and converts it into electrical ...
0
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1answer
49 views

Specific frequency signal detector

How does for example a generic signal detector (E.G. this cellular frequency detector circuit) actually pick up on a specific range of frequencies? (for 4g im assuming its around 900Mhz?) In ...
1
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2answers
62 views

Designing Precision Instruments: what to self-calibrate, what to guarantee by design

Context: I am working on a precision instrument (digital output) to measure current to systems, in the range between 300nA and 300mA (120dB). However, I hope that this question can be answered ...
4
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1answer
262 views

What is a good process to replace a discontinued part?

I have been looking about (on the web and printed catalogs) attempting to replace a part that is now discontinued. The experience has been part success - and part failure. A part is available to use ...
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8answers
1k views

Engineering Electronics: which approximation is usually good enough?

I have a strong computational background, so approximations with floating point precision depend on the type of computation. One thing is to know how to make an approximation and another one is when ...
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1answer
105 views

Why does the Apple Watch use a wireless charger, even though such a charger works slower than a MagSafe-like wired connector would? [closed]

The Apple Watch includes a built-in lithium polymer battery (a few hundred mAh; slightly more than 3.75 V) which is recharged using a wireless inductive charging cable. The cable does use magnets to ...
0
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1answer
95 views

How to modify existing circuit to additionally control it from outside by raspberry?

I found a great circuit for light home automation: circuitdb.com, but I would like it to be more than a momentary light switch bricked up in the wall.I would like to control it by raspberry or ...
6
votes
3answers
467 views

Is it OK to inject voltage to an unpowered LDO output?

I'm designing for the first time a PCB that can be powered from an external +12V supply or from the USB connector. In the input of the board, just after the power connector (VINLDO net is the +12V ...
2
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3answers
146 views

How was the design of active filter topologies arrived at, invented or discovered?

Active filters make use of Op-Amps. This can make it possible to avoid using inductors and get the same effect by "reversing" a capacitor. There are multiple topologies in existance for these active ...
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0answers
28 views

Capacitor ESR meter IC

G'day All I am working on building an ESR meter for testing capacitors in circuit. I figure I need a circuit capable of generating at least 200kHz. Looking around I found the Exar XR2206 which ...
0
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1answer
138 views

How to generate highest voltage possible without sparking?

I need to precisely control high voltage in order to maximize the corona discharge zone while preventing arcing for a physics apparatus. The actual voltage when the corona breaks down will vary ...
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2answers
91 views

Unused select line combination in 3x1 MUX?

While designing a 3:1 mux we require 2 select lines, but one combination is not useful, say 2'b11. If this combination occurs the output becomes 0 irrespective of the value of input lines. Is not the ...
6
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1answer
757 views

Why would a transistor have its base and emitter tied to ground when its collector goes to another base?

OK, calling me an amateur is being polite. But I am trying to learn more about how these circuits work. One example I am learning from is the ZX Spectrum ULA ...
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0answers
22 views

Getting started with CAD simulation

I'm playing around with CAD and drew lady ada's Powerboost 500's schematic, which is a USB battery booster. Typically when designing a booster like that, what sort of simulations/analyses are useful? ...
0
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1answer
66 views

Should I use a regulator to improve efficiency or safety

I am considering a low power design where I do not use a regulator. The components will operate from 1.9 to 3.7 Volts. The design is powered from two primary cells(Nominal Voltage: 1.5 Volts ...
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0answers
29 views

issue with optocoupler design for controlling 24volt pulses [duplicate]

to convert 24v pulses varying in frequency. max frequency 5khz. what optocoupler should i use to connect to microcontroller operating at 5volts. will a voltage divider be better in this case.> ...
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0answers
37 views

Transformer specifications to get 40V ac output from 210-250V ac in Proteus simulation

I want to design a transformer that connects to the ac main in proteus, steps the voltage down, and gives an output voltage of approximately 40 V. The core is made of f-type plates. The primary ...
31
votes
7answers
3k views

Is circuit design based on min/max values good practice?

Time and again I am arguing with a colleague of mine about the question above. When I design a circuit for mass production (> 10k/a) I want to make it robust against every possible variation of ...
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0answers
72 views

Static electricity motion sensor [closed]

Is it possible to make an efficient motion sensor using only transistors?I tried this with a couple of NPN and PNP transistors and then with a MOFSET .When someone walked by , a LED would turn on , ...
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3answers
100 views

Capacitor voltage influence

I have edited the question to make it easier to explain what I am asking for.To make it clear , I have deleted the part with the 555 timer. I have a question regarding the following : I know that ...
3
votes
1answer
67 views

Splitting a big Power Trace to several smaller

I would ask if i can layout a big trace and split it into many smaller ones (see attachement) I need to run a trace capable of handling ~5A. But the trace would be too thick to fit between the pins ...
0
votes
1answer
77 views

How to restrain this soft latching power switch from eating too much current?

I am designing a two buttons soft latching power switch for a project involving a raspberry pi, li-ion cells I salvaged from the battery of a broken laptop, and a power booster from adafruit. I ...
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0answers
51 views

Adding a regulating circuit to supply 3.3v

Background I wish to power my circuit with a 18680 battery. My circuit actually has two parts: 1) a 18650 charger and power booster for USB at 5V, and 2) a Bluetooth LE module (running at 3.3v with ...
0
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1answer
33 views

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 ...
3
votes
2answers
52 views

Need help modifying a motion detector circuit

I'm working with my son on a 4-H project, and we have great ambitions, but very limited knowledge. We're looking to use a motion detector to switch off the current to electromagnets that will hold ...
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1answer
161 views

How do I design 5-to-32 decoder using 2-to-4 decoder?

As there are 32 outputs in 5-to-32 decoder so I will have to use 32/4 = 8, 2-to-4 decoder. But then I have total 16 inputs. As I want to create 5-to-32 decoder so I need only 5 inputs, what do I do ...
4
votes
2answers
76 views

Design question regarding high current wires running below PCB

I am working on a layout that will look similar (not final) to the illustration below. There are three high gauge wires (red) 3x230VAC passing directly below the PCB (isolation touching the PCB) that ...
3
votes
2answers
358 views

Complexity vs Space in Schematic

I got a screw terminal with the following pin configuration: ...
0
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0answers
46 views

Help Designing Microcontroller 2xRj45 (RS232) + 1USB-Serial

I am trying to design a microcontroller that will have 2xRS-232 RJ45 ports (not PoE, just serial communication) and a 1xUSB Type B female (for 5V power and programming). I am not exactly sure, but ...
2
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2answers
259 views

In a 74HC14 Schmitt trigger IC, unused inputs/outpus

I have a 74HC14 Schmitt trigger IC. I only use one of the I/O pairs, and everything else is not used. I understand that in TTL logic the unused the inputs should be set to either high or low to ...
3
votes
2answers
150 views

How to find a way to detect if a device was opened or not

I'm making a device which is inside an enclosure and at this point of the project it's relevant to understand if the enclosure/box was opened. I was trying to understand if I can try to figure it out ...
1
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1answer
77 views

Improving a processor design in VHDL

For a project at my university we have to improve the design of a processor (more specifically, the Plasma CPU. The design is generated based on a description written in VHDL. We have to identify ...
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3answers
125 views

PNP Transistor Leak

I have a problem with a circuit that should be simple but has caused me some annoying problems. Summary: I need a switch that closes when the power is off and opens when the power is on. My solution ...
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0answers
76 views

LED Matrix design in Logisim to display a count sequence

I've built quite a large circuit (at my level) that generates outputs d3, d2, d1 & d0. d3 and d2 are generated by a multiplexer / OR gates and d1 / d0 are generated by an 8-1 MUX. These outputs ...
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0answers
101 views

Tantalum Capacitors to Electrolytics Capacitors/Ceramic Capacitors

I'm trying to reduce costs from my design and one of the things that I'm thinking about is changing the Tantalum capacitors to Electrolytic ones with low ESR. P.eg. I'm applying one Tantalum ...