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

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1answer
77 views

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

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
votes
1answer
88 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 ...
5
votes
3answers
432 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
votes
3answers
140 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 ...
0
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0answers
24 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
108 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 ...
2
votes
2answers
81 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
votes
1answer
725 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 ...
0
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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 ...
0
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0answers
27 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.> ...
0
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0answers
29 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 ...
30
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 ...
0
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0answers
69 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 , ...
1
vote
3answers
96 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
63 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
65 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 ...
0
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0answers
46 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
votes
1answer
32 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
51 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 ...
-1
votes
1answer
100 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
74 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
348 views

Complexity vs Space in Schematic

I got a screw terminal with the following pin configuration: ...
0
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0answers
44 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
votes
2answers
247 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
148 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
vote
1answer
76 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 ...
1
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3answers
112 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 ...
0
votes
0answers
64 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 ...
0
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0answers
94 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 ...
0
votes
1answer
125 views

D.C power supplies, regulated linear power supply question

Design giving the necessary ratings and characteristics the necessary for the transformer, bridge rectifier capacitor and regulator , a 12v , 2A regulated power supply . the available mains supply is ...
1
vote
2answers
138 views

How to design blinking LEDs circuit using analog elements only?

I want to design a circuit to blinking three LED in a row with 2 second delay for shifting/changing using analog elements only (using Resistors, Capacitors and Transistors and without Micro ...
0
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0answers
20 views

Circuit to integrate BeagleBone Black with Pressure Regulator

I am using BeagleBone Black as controller to control a proportional pressure regulator (Festo VPPM-6L-L-1-G18-0L10H-V1P-S1) which is the actuator of my project. The pressure regulator has an input ...
4
votes
2answers
173 views

Advantages of depletion mode FET devices over enhancement MOSFETs

I've grown the impression that JFETs and depletion mode MOSFETs are not used very much nowadays, especially in new designs. I know that they need different bias networks, especially as discrete ...
1
vote
3answers
191 views

How does one approach designing an amplifier using BJTs to drive an 8 ohm speaker?

For a lab class we were assigned a final project where we have to design an amplifier using BJTs, diodes, and capacitors (MOSFETs are not allowed) in order to drive an 8-ohm speaker. The requirements ...
3
votes
1answer
75 views

Where do these values come from?

Looking at an ATMEL SAM4E and I'm looking at the schematic checklist published by Atmel for the SAM4E and the schematic for the SAM4E-EK developer board. SAM4E checklist SAM4E-EK Design files ...
0
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2answers
123 views

Dual rail switching PSU critique

I am looking for feed back on the following power supply design. This power supply is intended to have 2 outputs: 24V @ 500mA and 32V @ 850mA. When the power supply is in standby, J1 pin 1 is @ 0V, ...
1
vote
1answer
79 views

Is my Rigowksi Coil turns calculation correct and how to calculate the sensitivity?

First, I would like to show my calculation. Please correct me if I'm wrong. Suppose the maximum induced voltage in the coil is 250mV and the current to be measured is maximum 1000 A. So, the current ...
0
votes
1answer
111 views

How to Design Arduino Voltage and Current Sensing Shield

I am trying to design an Arduino shield that measures raw voltage and current of a small refrigerator (115V, 60W). I have an Arduino Mega board. To one of the ADC inputs I have connected a (non-split) ...
5
votes
3answers
547 views

How do integrated circuit design companies create their datasheets?

Especially for something like a microprocessor. I assume the majority of information is "auto-generated" or we'd see a lot more typos and errors. A laughable scenario keeps popping into my head ...
2
votes
1answer
118 views

JFET biasing problem

I tried solving this problem, however I feel like there's something missing, I am asked to bias a N-channel JFET with using this provided data: Idss= 12 [mA] VDD= 12 [V] VP = -5 [V] VDS=VDD/2 ...
16
votes
6answers
2k views

New to PCB design - why doesn't auto placing components exist?

The circuit design software I have seen has the ability to automatically route traces etc. on a PCB. But why doesn't this software have the ability to automatically place components on a PCB say to ...
0
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0answers
42 views

Hack Quartz Clock Movement with Chronodot

I'm working on creating a clock design that will use an off the shelf Quartz Crystal Clock Movement. I know they are not all that accurate and was thinking of a way to make it more accurate. My ...
3
votes
2answers
322 views

How to create a frequency doubler circuit using only flipflops/ Digital elements?

First things first, is it even possible to scale up the frequency using only digital elements, atleast approximately? Though a frequency divider circuit can be designed very easily with flipflops. In ...
1
vote
1answer
67 views

How do you design a circuit to implement the Bipolar Line coding Technique?

Bipolar NRZ http://www.tutorialspoint.com/data_communication_computer_network/images/bipolar.jpg In this technique alternate 1's will have alternate polarities and 0's will be zero itself.
4
votes
2answers
73 views

Design Considerations for Raspberry Pi Expansion Boards

I am venturing into the space of designing expansion boards for Raspberry Pi's. I have done this for Arduino boards but RPi's are a different beast. From personal experience I have already had ...
1
vote
0answers
56 views

Critique and dos/don'ts for an H-bridge PCB design?

Honestly have no idea if this is something this site was made for, but I have a couple of questions about my design, mainly it comes down to "Will it work?" and "Why would it break?". JC1 and JC2 are ...
3
votes
1answer
173 views

Sequential Traffic Light Controller

Just for clarification: I'm just looking to see if I'm on the right path for this project and to figure out what the best plan of attack might be. I'm trying to simulate a sequential traffic ...
0
votes
2answers
432 views

Designing an 8 x 3 memory chip given 2 4 x 3 chips

I'm working on a problem that asks me to design an 8 x 3 memory chip given 2 4 x 3 memory chips. I'm not sure how to approach this problem. I've looked at the textbook and found various online ...
1
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1answer
300 views

Micro and Nano Memory, Calculate Reducing Bits?

I ran into a question: in digital system with micro-programmed control circuit, total of 32 distinct pattern operation signal is ...