texts: What makes the self-inductance in a series LR circuit to fail stopping current forever?

texts:
This might be absurd question for many here but I'm trying to picture a bit in depth what is happening in an LR circuit and confusion arises.

Below is how a series LR circuit behaves when the switch is turned ON:

I can understand the basic explanation and the derivations.

But there is a particular part that confuses me here conceptually.

The texts mention that, the moment the switch is turned ON the current wants to increase but due to the self-inductance an opposing voltage induced as -L*di/dt which is equal to the battery/source voltage hence no current flows at time zero. The equations also support that.

But they say: The self-inductance is fighting the current's will to go through the circuit, and there comes a time that the self-inductance loses the fight if we wait long enough and eventually the current reaches to the maximum value.

All of these are clear if we look at the equations, but what really happens at the coil that there comes a time that the self-inductance loses the fight? I mean why doesn't its induced  opposing voltage stay constant forever and stop any current flow? Is there a more phenomenal explanation rather than maths here?


texts: How to connect laser with common LD-Anode and PD-Cathode, tied to laser case

texts:
I am wanting to experiment with transmitting data over air via lasers.  This D650-5i laser diode has a built in monitor diode.  It is 650nm, 5mW, 3 pin component.  I'm really only using this laser because it is in the visible spectrum, and I assume it would be easier to learn with if I could actually see a beam.  I would probably switch to an OPV314Y once I was comfortable that the laser circuit was functioning.  It is the same basic pin layout -- just 850 nm.

Pin 1 - laser cathode
Pin 2 - Common case (laser anode, monitor cathode)
Pin 3 - Monitor anode

From what I have read, I should ground Pin 2 because it is tied to the case, which means that Pin 1 would need to be tied to negative voltage in some way.  Since I am wanting to transmit data, I believe that I want a laser driver in the mix.  I have found ADN2873 (datasheet on Mouser or Analog Device's website) -- but all of the schematics I see seem to be for a different laser configuration (V+ applied to laser anode, GND to laser cathode).

So my basic questions are:

Will this laser configuration work with ADN2873?
If #1='No', should I look for a different laser pin-out, or a different laser driver?
If #1='Yes', what do I need to do differently to hookup the ADN2873?  Would I need to use something like an LM7905 to get a negative voltage, and then essentially change all GND's to V- and all V+ to GND in the schematics from the ADN2873 data sheet?
On the ADN2873, it looks like there are two basic ways to configure it.  One way is with a microcontroller, and using two of its DAC lines to essentially set the desired laser output.  The other way is to use resistors.  If I used the first way (voltage), and the answer to #3 involves using an LM7905, would the voltages from the DAC lines need to be negative too?

I may be on the wrong track with this -- so feel free to tell me I'm thinking about this completely wrong.

Just to give an idea of my level of expertise...I don't have any formal training or professional experience with circuits, but I have played with arduinos, raspberry pis, XBee radios, etc.  I have designed a set of circuit boards in the past with 8 bit ATMEL chips (ATtiny841 & ATMEGA 328p) that controlled 2 XBee radios via SPI -- it was basically a glorified remote control for turning LEDs on and off from a distance.  So I've learned quite a bit about electronics on my own, but it is entirely possible that I am ignorant of some very basic concepts.


texts: How to reverse engineer a motorcycle speedometer?

texts:
I hope this is the correct forum for this type of question.
I'm trying to start a project to figure out and create a replacement for my motor cycle speedometer.

my goal is to take the current unit, understand how it works and then figure out a design for a replacement speedo.

The speedo in question is a digital display with several discreet inputs to set off warning lights.

There are also control buttons to change modes and reset displays.  All inputs are electrical from the wiring harness and possibly one input that is digital from the ECU.

Mostly i am looking for help and advice on how to go about figuring out this problem more than anything.  I am a software engineer but i have never worked on anything remotely like this.


texts:
Good day,

I found this question asked before (not exactly this) but the answers were wrong (at least at some level).

So i have two 300W PSU's (different manufacturer so different schematics too). I don't really have any purpose for them but i could use a 24V high amperage (up to 10A) power supply.

So i took one apart, disconnected ground from few screws to chassis (just so that output ground would not be connected to socket/chassis ground). I left ground for all other uses (chassis, grid and some other grounds are all connected). Now i had output ground separated from main ground. I then supplied 12V from other PSU to first PSU's ground. Voltage between PSU1 ground and PSU2 12v then became 24v. 5v became 17, 3.3 became 15.3...

So my question is this: Since all i could find was that this is impossible/very bad to do, it kinda contradicts my findings. The 24V output did hold over 7A load and it seemed to not matter in which pattern i turned them on (i turned "free" PSU first, then the "non-grounded" one second). Is it really that bad to use those PSU's this way? Is it "theoretically bad" or like "100% break down pretty soon"?


texts: Does the concept of damping apply to 1st order systems?

texts:
I'm just learning control systems. Today I learnt about 1st order and second order systems.
I understood Damping, Critically damped, over-damped and under-damped systems.
So a question arises in my mind "Does the concept of damping apply to 1st order and if so, whether all 1st order systems are over-damped or critically damped only?"
My thought is because 1st order systems don't have energy transfer element pairs such as capacitor and inductor like in 2nd order, so oscillations can never happen.
Is my thinking correct or am I missing some points here?


texts: Why is this circuit letting the smoke out?

texts: Using this circuit as a proof of concept to run a 12v motor off a 12v wall wart and ultimately use the 5v from the 7805 to power a Particle Photon through Vin pin. This circuit is letting the smoke out for some reason though when the switch is closed.


texts: Is it possible to design a 3-axis solar tracker using three stepper motors just like dual-axis solar tracker in which we use two stepper motors one for elevation and one for azimuth?


texts: Software identification of a DIY (guitarist) CAD application

texts:
I know there is a reasonably popular tag for component identification, however I have a question about software identification.

Before I used KiCad (when started with electronics), I used for a while a very simplistic 'CAD' program for perfboard layouts. However, I reinstalled my PC since, and I cannot find the name of the application anymore. I need it because I want to open the (complete) layout I made for an old project to see if I can 'revive' it.

I only have a screenshot and some info about it... it was meant mostly for guitarists, and it was (afaik) only possible to make some kind of perfboard layouts). The internal components where very basic and some guitarist specific ones.

The application extension is .diy and the name also had DIY in it (I think), but DIY is not the most easiest keyword to search for on Google.

I would like to know the name (or link) of this application, so I can install it (at least temporarily) to see my old design.


texts: filters for in-amp, difference amplifier, and non-inverting op amp

texts:
I am new to this matter and would like to learn how could I determine the right filters to use for my circuit. I have read some tutorials about active and passive filters but can't get the right values for it. I have also read about the formula of getting the values but dont know how to determine the corner frequency of my circuit.

I am currently making a basic circuit for a weighing scale and I want to know what type of noise affects my load cell output as well as my op-amps. I use AD620 as my in-amp.
http://users.ece.utexas.edu/~valvano/Datasheets/AD620.pdf

and AD822 as a difference amp and a non-inverting amp since it is dual.
http://www.analog.com/static/imported-files/data_sheets/AD822.pdf

Based on the datasheets, I can't determine what part of the characteristics would be a help to know what filter and values are needed. I think I need filters between my load cell and in-amp, and also for the non-inverting and difference amp.

Sorry for the noob question but any help would be appreciated and I am willing to learn.
FYI, I use a full-bridge load cell for my pressure sensor.

Here is my circuit:


texts: Will this circuit suffice for low battery detection for any microcontroller?

texts:
I'm making a major digital circuit powered by two 3.6 volt cordless phone NiCD rechargeable batteries, and one thing I want to include is a low battery detector. To protect the rest of the circuit from overheating, I use a typical 7805 voltage regulator circuit to give all my circuit 5 volts.

What I want to do is detect if the source battery is too weak to power the rest of the circuit and allow a microcontroller to detect it via a GPIO pin's logic state.

Because digital circuits ideally run on 5VDC, I figured using a zener diode rated at 5.1V with a 10K resistor for R1 would be sufficient to detect the low voltage itself but I'm not sure if it would explode the GPIO pin even though its pulled up by 5V through R2 which I may also make as 10K.

Questions are:

Would this circuit have potential to work or would connecting fresh batteries equaling the same voltage explode a GPIO pin?

Also, is 10K an ok value for the resistors or should I choose something different?

The microcontroller in question is at89C2051.


texts: Which one is efficient verilog code in this if statement?

texts:
I have following verilog code:

wire cond1;
wire cond2;

assign cond1 = a & b & c;
assign cond2 = a & b;

if (cond1)
   ...
else if (cond2)
   ...

we can do this in another way:

wire cond1;
assign cond1 = a & b;

if (cond1)
  if (c)
     ...
  else
     ...

Assuming the expression of c is long enough, which one is the efficient way from the perspective of hardware?


texts: How to find rated current of a three phase induction motor

texts:
How to find the value of full load rated current and rated current for a three phase motor having its ratings as:
Stator resistance and inductance = [0.2147 ohm, 0.000991 H]
Rotor resistance and inductance = [0.2205 ohm, 0.000991 H]
Mutual inductance = 0.06419 H
Nominal power, voltage (line-line), and frequency = [1.5e+04 VA, 400 V, 50 Hz]
Pole pairs = 2
Load Torque = 5 N-m

I am currently doing a project on simulating Blocked rotor test, DC test, No load test in MATLAB on three phase induction motor and in order to do that I need to find the rated current and machine ratings doesn't has its rated power factor or efficiency mentioned on it...


texts:
Can someone explain "constant-current" circuits?

When are they necessary?
What happens without one?
What's the simplest version of such a circuit?

I bought some 20W LEDs off ebay intending to make a bike light.  "Simple," I thought, "The LED and my laptop battery are both 11Vdc, so I'll just connect them."

I haven't actually tried this, but an EE friend suggested that if I do so, it will draw too much current and burn out -- but he didn't know why; he doesn't do power electronics.


texts: Inductor dimensions as a function of time(?)

texts:
While perusing the text book "Foundations of Analog and Digital Electronic Circuits" by Anant Agarwal , I came across this text in the section on inductors:

Why are the dimensions of the inductor a function of time if the geometry of the inductor varies from the toroidal shape?


texts: DIY : Powering a single LED with a motherboard's internal connectors

texts:
I'd like to power a bright LED (1W or 3W) connecting it onto a power source of my computer, directly on the motherboard. I think about using either a fan connector or directly the ATX Power supply. But I don't find any information about how to do that well on the net.

I will have to use a resistance, a led, some wires and perhaps a power switch, and probably some cooling stiff for the LED and the resistance. But what about what-to-do and what-not-to-do about such a DIY stuff ? I mean, what may I connect onto what, what must I take care about, ... ?

examples : the fan connector has 3 pins. My LED has 2 pins...
Making such a connection may damage the motherboard ? What may I do to prevent this ? What about the voltages and power ?

I was starting this with confidence, but not finding anyone that talks about that on the net makes me a litlle be scared.


texts:
For a current project I am attempting to amplify and cross-wire the signals from the address pins of SMD RAM chips. Basically this means I am trying to break out the pins of a SMD chip, similar to how one would do with a SMD breakout board for prototyping, except in this case the SMD chip is soldered and operational in-circuit. I want to be able to measure the signals and interconnect them in a stable way --- at the moment I am soldering magnet wire to the individual pins and it is incredibly fragile and the soldering itself immensely difficult.

The chips I am attempting to break out are in a 0.8mm pitch 50pin TSOP II package (see attached image). Perhaps there is a custom option? Or some other clever solution?

Your thoughts and suggestions are very appreciated.


texts: Inrush current calculation in capacitive circuite.............?

texts:
I am using the following circuit to make a transformer-less AC to DC converter.
It is working fine in my case. Now I need to protect my rectifying diodes from damage due to inrush current in this circuit.Here the resistor R4 is used to limit the inrush current.So to select a suitable value for R4 I need to calculate the maximum inrush current current in this circuit.
So how can I calculate the inrush current in this circuit........? What about the surge power in R4?
What will be the suitable value for R4....?


texts:
I have dissasembled a pick up head from a CD Rom. I can control the laser and but I also want to "read" the photodiode that senses the light reflected back. It is packaged in a clear plastic and has 8 pins. I can't see the entire ic but I can access 4 of its pins. Now I'm trying to determine what those pins do but I need more data about how they operate. I found a very similar device OPT101 that explains many of the external components of my photodiode. Beside the ic there are 2 capacitors,1 fixed resistor and one variable resistor.

Although the datasheet is different from my ic there are many similar traits.

Counting pins from left to right, here are my assumptions:

I think pin 1 is the actual output. From the datasheet , the feedback resistor(1M) is connected to output.
Pin 3 is ground.
either 2 or 4 is vcc(one of them I think is -V which I don't need)

I say pin 3 is ground because 2 and 4 are connected through a capacitor to this line.

To test which line is vcc I think there is a way: simply,if I connect the right line to 5v(or the lowest amount of voltage possible so that in case of wrong assumptions the damage will be minimum) the chip will work and I will be able to read the voltage from Output. If it's the wrong pin deduce the other one is vcc and hope the chip is still good.

What I want is more datasheets from similar products. If ,from your experience , you have seen anything like this one please write about it. And am I missing something(like the capacitors actually could be wired to vcc) that may help me find the pins ?


texts:
I just received my TI Launchpad and I'm wondering how can I add something like an Ethernet Shield from Arduino, in order to display a simple webpage... ?
Do you know any Ethernet shield for Launchpad?


texts: How does an "if" statement and "always@" statement work in Verilog?

texts:
I'm trying to program an 8 level stack register for a Program Counter. It is working well enough, but for some reason, when I test it, some combinations of inputs produce unexpected results. This is leading me to believe that I don't really understand the underlying logic behind the "if(condition1 && condition2)" statement or the always@ statement (Statement? I'm not really sure how to call it). I don't care if it is synthesizable. I just feel that I'm missing something.

Here is the code:

  module Stack(
  // Buses
  inout [12:0] BUS_Stack,             // Bus used to exchange data between Stack and PC
  // Inputs
  input logic WE_Stack,               // Write Enable. WE = 1 Stack sends data to PC
  input logic RE_Stack                // Read Enable. RE = 1 Receives data from PC
  );

  // Internal variables
  integer i;                          // Variable used for "for loops"
  reg [12:0] Stack [0:7];             // Stack matrix. A registry is used for it to have "memory"
  logic [12:0] Data_To_PC;            // Internal variable that manages the writing process to BUS_Stack
  parameter Height = 7;               // Constant for the number of layers that the stack has. Given in (N-1) bits

  // The bus between PC and Stack is set to Z when WE_Stack = 0;
  assign BUS_Stack = (WE_Stack && !RE_Stack) ? Data_To_PC : 13'bz;

  always @(BUS_Stack or WE_Stack == 1'b1 or RE_Stack)
    begin

      // Receive data from PC
      if (!WE_Stack && RE_Stack)
        begin
          // Downward PUSH to all elements in the Stack register
          for (i = Height; i > 0 ; i = i - 1) Stack [i][12:0] = Stack [i-1][12:0];
          // First Stack address <- Bus
          Stack [0][12:0] = BUS_Stack;
        end

      // Send data to PC
      else if (WE_Stack && !RE_Stack)
        begin
          // Stack's first row is asigned to the Bus
          Datos_A_PC = Stack [0][12:0];
          // Upwards PUSH to all elements inside the stack register
          for (i = 0; i < Height ; i = i + 1) Stack [i][12:0] = Stack [i+1][12:0];
          Stack[Height][12:0] = 13'bx;
        end

    end

endmodule

Here is the testbench I'm using:

//----------------------------TESTBENCH--------------------------------

module testbench();

  // Inputs and Outputs
  logic WE_Stack, RE_Stack;
  logic [12:0] PC;
  wire [12:0] BUS_Stack;

  // Connection to module
  Stack STK (.WE_Stack(WE_Stack), .BUS_Stack(BUS_Stack), .RE_Stack(RE_Stack));

  // Assign statement used to simulate the Stack bus receiving data
  assign BUS_Stack = (!WE_Stack && RE_Stack) ? PC : 13'bz;

  initial
    begin
      $monitor("WE_Stack: %b \t RE_Stack: %b", WE_Stack, RE_Stack);

      #1 WE_Stack = 0; RE_Stack = 1;
      #1 PC = 13'd7;
      #1 PC = 13'd21;
      #1 PC = 13'd1;
      #1 PC = 13'd144;
      #1 PC = 13'd5;
      #3 WE_Stack = 1; RE_Stack = 0;
      #1 WE_Stack = 1; RE_Stack = 1;
      #1 WE_Stack = 1; RE_Stack = 0;
      #1 WE_Stack = 0; RE_Stack = 0;
      #1 PC = 13'd4;
      #1 PC = 13'd68;
    end

  initial
    begin
      #120 $finish;
      $dumpfile("dump.vcd");
      $dumpvars(1);
    end

endmodule

The problem appears after the line

#3 WE_Stack = 1; RE_Stack = 0;

The program is supposed to write to PC only once, but when simulated, it produces about 7 write operations to the PC.


texts:
Three edge-triggered JK flip-flops in a synchronous circuit have the following input conditions.

JA = QB     KA = 1
JB = 'QA    KB = 1
JC = QB     KC = 1

Assume that the initial state is QA = 0    QB = 0     QC = 0 Find the count sequence

I'm having very difficulties how to solve this problem.

And also i found the answer. but no idea how they solved it? can anyone help me

Answer : http://bit.ly/1mhIosR


texts: What kind of oscilloscopes are qualified for measuring USB 3 Super Speed Signals?

texts: I understand that they probably will be very expensive. But I have little idea of what kind would qualify. How much bandwidth? At what sampling rate? Any other parameters?


texts: Can Zener or Schottky diodes be used as a substitute for varicap diodes in tuning a VCO?

texts: In particular, this would be a fairly low frequency VCO with a frequency range of 10 Hz to 20 kHz. I'm thinking of the configuration with the T-junction that has 2 opposite facing, reversed biased varicap diodes and a resistor perpendicular to the intersection point.


texts: How to read multiple sensors, store into an array, sort and then do something with the results—Arduino

texts:
I have a small project that I could use help understanding how best to move forward.

I have a set of 8 batteries of different voltages and age.

I’d like to read the voltages of all, assign an identifier to each battery , store those voltages in an array (I assume), then sort the array from the highest voltage to the lowest, pick the top 4 highest voltage batteries, and then “do something” (like light a led next to each of those 4 batteries indicating the top 4 highest voltages).

Although I’m quite a Arduino newbie, I do know how to read the battery voltages. The rest I have a vague idea but really stumbling with how to sort and then do something with the curated sorted list.

Thanks for any help or guidance!


texts: Stepping down 12VDC linear power supply to 9VDC

texts:
I have a +/-12VDC power supply that I have built up for testing simple audio circuits. It works just fine for me now but I would like to add a permanent +9VDC leg to it. I have never seen a scenario where one linear regulator feeds another which is why I haven't simply connected a 7809 to the 7812's output. The 9VDC leg I need would also be for audio circuits (but they won't need the bipolar supply just the +9 and GND). Current draw of the 9V leg won't exceed 100mA. The +/-12V supply never needs to put out anymore than 100mA as well. I am trying to determine a smart way to drop the 12V to 9V while keeping the supply clean and quiet (audio circuits) and not generating a lot of heat (anymore heat than a normal linear regulator generates).

simulate this circuit – Schematic created using CircuitLab


texts:
I can't wrap my head around how the SR Latch works. Seemingly, you plug an input line from R, and another from S, and you are supposed to get results in Q and Q′.

However, both R and S require input from the other's output, and the other's output requires input from the other other's output. What comes first the chicken or the egg??

When you first plug this circuit in, how does it get started?


texts: Selecting a capacitor for use in feedback loop

texts:
I'm designing a DC Lab Power Supply; the voltage regulation circuit looks like this:

I'm developing the BOM, component by component, and next in line is specifying the capacitor in the feedback loop for the op amp, C1 in this schematic.

As I'm going through the selection of specific components, I've developed a new appreciation for the diversity of available capacitors and the relative complexity of what I originally thought was a pretty straightforward component type. So my dwelling on this particular component is as much for the learning opportunity it presents as the desire to pick the right item for this specific case.

My PCB is SMD wherever possible, and I'm inclined to believe a garden-variety 0805 X7R would do the job just fine. However, I've learned they can have surprising behaviors depending on, for example, the voltage applied, so wanted to get the perspective of more experienced designers.

The design of the feedback loop itself was by far the biggest time investment in the circuit overall. I had to refresh my foggy recollection of Body plots, transfer functions, op amp particulars, etc. And it took me quite a few tries to get it this right (and understand why it worked then :). So I'm inclined to think if there's anywhere in the overall where the capacitance in critical that this would be it.

So my question is: Is a regular surface-mount ceramic cap the right choice for using in this feedback loop? Or should I be thinking something a little fancier, like perhaps a film capacitor of some type?


texts: Raspberry PiFace, need to put 14 gauge wire in 1.5mm terminal

texts: I have a PiFace and I need to get at 14 gauge wire which is 1.63mm thick into a 1.5mm screw terminal. To pass 4 Amps at 24VDC. I only have 14 gauge and 22 gauge wire, the 22 gauge wire won't pass all the current I need. So, are there any ideas on how to connect this... File the wire, etc.


texts: Familiar with the FFT and LabView. Can I use LabView to compute and display the FFT of an analog signal in real-time rather than computing it from a data array?


texts: How to interface a SPDT switch with Mac OS X

texts:
Before I get started, I am a software developer and I have extremely limited knowledge of circuitry, so please be gentle.

In it's most basic form, I guess my question is, how can I wire up a SPDT switch so that when I change its position, a signal is sent to my Mac running OS X as an input device?  I want to build a panel of switches for use with a flight simulator (X-Plane 10) running on my Mac.

Originally, I planned on purchasing this:Desktop Aviator Model 2237.  I would then solder a number of switches onto the circuit board and when I flicked a switch, the processor would recognise the change and send a 1/4 second signal to my Mac, which would be picked up and used as an input into my flight simulator to flick that particular switch in the simulated world.  The end product would end up looking something like this: Desktop Aviator Model 2620.  Unfortunately, the circuit board is not compatible with Mac OS.

Is there a way I can buy (or create) something similar that will work with my Mac?

I have had a look at a few other questions on here and found

  electronics.stackexchange.com/questions/74/pic-microcontroller-programming-on-mac-os-x

most relevant, but not particularly helpful.  (Sorry, can't post more than 2 links with my lack of rep on this site).  One of the answers to that question referenced this product:

  www.teammojo.org/PICkit/pickit1.html

, but I am not sure if this is what I am looking for (as in, I don't understand what it does).  As I said, I am absolute beginner and I understand that the Mac side of things isn't particularly well documented.  My initial Google searches just returned a heap of OS X Cocoa code for programmatic switches.

Are there any tutorials or articles that might point me in the right direction?

Thanks a lot in advance.


texts: How to display SMD footprints in Eagle CAD as separate layer instead TOP or BOTTOM

texts:
I would like to print Pads, Vias, SMD footprints altogether so that I can apply UV solder mask on board. The problem is that the SMD footprints is part of TOP layer.

What to do?

Looks like correct layer would be tStop, but it appears stripped instead of filled. Looks like I should use some image editing software to fill those pads manually.. .


texts: Can I work 30 of these Solenoid Valves from a battery?

texts:
The (30) solenoid valves are 12v, all identical, each controlled by a relay and are rated at 6.2 watts of power consumption.
They will all be turned on simultaneously and turned off separately. This will happen frequently, once every few seconds.  The battery can be charged regularly.

What ah of battery is required? Deep cycle?
Also what is the calculation? (so as to work out variations)

Thanks very much in advance


texts: Is this a valid configuration for decoupling capacitors on an IC with two supply pins?

texts:
I have a project that's using an IC that only comes in SMD packages.  With my limited soldering experience, I think I could potentially solder a TSSOP, but I think QFN is well beyond my capabilities.

I decide to try to make a PCB that adapts the TSSOP to a DIP profile compatible with common breadboards.

This particular IC (NXP PCAL6416A) has two supply pins, one for the I2C bus and one for the GPIO ports (this is an IO expander).

Would this capacitor placement and configuration potentially work for decoupling my two supply pins?  Would it be a problem if both pins are on the same supply line vs. different ones?

This is the PCB layout:

This is the schematic:

Thanks very much!

Edit:

In case other hobbyists come across this question and would be helped by a visual representation of the answer, here's the latest implementation I have based on my understanding of the solution:


texts: Exists an Arduino compatible temperature sensor with effective range of approx 1 meter?

texts:
I saw this fictitious product on the web and was impressed: http://www.behance.net/gallery/Sprout-Infant-Monitor-System/4033245  However, as I said the product does not really exist, but the seed is planted and I seek to find a means to achieve something similar in the DIY fashion.

At the moment I'm only interested in the temperature reading from a distance feature.  I've run into a bit of a problem identifying a temperature sensor that is capable of taking a reading from any range more than 10cm.  I've scoured the Googles and found the most popular sensor was the MLX90614, but that is extremely short range from what I gather.  I was searching for any long range temperature sensor compatible with the Arduino, but only found a few that had extremely limited range.

There are other important factors such as precision, effective angle, and operating condition limits, but they are all less of importance behind effective range.


texts: How does a series capacitor affect a square-wave on-off signal?

texts:
This question refers to the book Make electronic's experiment 18.

I have included a picture below.

R7,R9,R10,R12: 1K
R8: 2K2
R11: 330K
C1: 100uF
C2: 68uF
C3,C4,C6: 0.1uF
C5: 10uF
S1,S2,S3: tactile switches
IC5,IC6,IC7: 555 timers
IC1: 4026 counter

quote from the book:

  When the output from IC7 goes from positive to negative, it will trigger the reset of IC6, flipping its output negative, which allow the count to begin
  The capacitor C4 communicates the sudden change from positive to negative, but the reset of the time it blocks the steady voltage from IC7 so that it won't interfere with IC6

My question: How does IC6's pin 4 get negative voltage or grounded? I thought C4 would only accumulates positive current from IC7's pin 3 and release it to IC6's pin 4.
I thought the capacitor should be hold fixed to connect one pin to positive, and another to negative. From what i can see the IC7's pin 3 is switching from positive current and then to ground on one of the pin of C4.

Thank you


texts: Precise & Stable current source (LED Driver)

texts:
I have a circuit to drive a string of series LEDs and currently we use a MCU generating a PWM signal which is adjusted to a BCR421 and then to the LEDs.

I was wondering if I could use the MCU output straight to my own current source circuit and then to the LEDs (thus eliminating all the components between the MCU and the BCR421). Generally those ICs have more stability and regulations then simple circuits so I don't know much less stable the circuit would be. For example using this one:

So it's suppose to work as a current source and have some kind of temperature regulation. However, using this kind of solution, would I still be missing other important characteristics from the BCR421? As my objective is to drive the LED, I need some current around 65mA that remains stable even with temperature changes.

In short, is it worth to make your own circuit or just take an IC instead?

UPDATE:

1) Why there's extra components between the MCU and the BCR?
Apparently the other designer said the MCU output was not strong enough in harsh environments as there's a few long lines (from 5 to 130cm) from the MCU to multiple BCR's (about 5 to 15 BCR's for each MCU).

2) I'm designing a product which is a lamp. It's probably going to be used in normal situations like homes and offices. The temperature is probably gonna range between ambient temperature to 70~80C.

3) The stability is needed only to guarantee a specific forward current in the LED's to keep the light quality/color very much stable (around 65mA for the LED we have now, for example)


texts:
We have the following closed loop system  where a is from 1 to 10 and p from 0 to 1(excluding 1).

We want to design controllers H(s) and C(s) so that the step response is inside this area

This is a problem from an exam sheet so a computer can't be used. Anything I should do is by hand.

Ι though C(s) could be just a gain C(s)=k. Then I get the following closed loop transfer function. $$G(s)=\frac{ka}{s+1+p+ka}$$ Now I could pick the right value for k so that my function in time domain decays faster than e^-2t which is the case shown in the picture. However steady state error can't be zero because I don't know where p is. Final value theorem for step input gives for s=0 $$y(t=\infty)=H(0)\frac{ka}{1+p+ka}$$ In other problems without p in the denominator I would set this equal to 1 and find H(s) but here p is a moving pole. What do I do?


texts:
MAX232 Datasheet

Hi, I am currently a student so bear with me please!

I'm currently using a powering the MAX232 with 5V DC, and when I measure from VCC to lets say, pin 3, I am getting a voltage reading of around 13V on my voltmeter.  Using a power source that is higher than 5V.  What is going on?  I know it says in the datasheet that there is a voltage doubler, but I am not quite sure how voltage doublers work, other than we need the capacitor.


texts: can switching regulators cause interference on wifi based circuits?

texts:
I read that buck and boost converter due its switching mode produces too many noises compared with linear regulators but it is more efficient.

Can those those noises cause interference on boards with wifi chips on it?

How would be a good way to measure how big would be such interference at the point to determine that it is worth to use a linear regulator even without power efficiency?


texts: Is the use of a lock in amplifier with a signal generator appropriate and practicable?

texts:
I want to generate a 5 kHz microwave pulse to induce a sample signal. This microwave pulse has an underlying microwave frequency of 2 GHz. In order to investigate very tiny signals, which should arise within my setup with a frequency of 5 kHz repetition, I want to use a lock in amplifier to differentiate my 5 kHz signals from the noise floor.
Currently I have a Hewlett Packard 83640B signal generator 10 MHz-40 GHz and a Zurich Instruments lock in amplifier HF2LI.
Can I use the lock in for generating the 5 kHz reference signal, put it in the signal generator which is then modulated with 5 kHz and generates a 2 GHz signal by its own which is sent to a microwave antenna?
The detection signal of my sample is of course used as input for the lockin, it compares the input signal to its internal reference of 5 kHz, and shows me how big my sample signal is.
Is this possible? Which obstacles do I need to handle? Is there another way if this setup wont work?
I am no physicist and no engineer, please keep your comments rather simple if you have a tip or good advice.


texts: Angle Random Walk Noise - MEMS Gyro Error sources

texts:
I am working in a implementation of a Dead Reckoning approach in a simulator. In order to take values more realistics I am considering this MEMS gyroscope (SMI130).

In this document is given this noise in FFT units:

0.02 º/s/sqrt(Hz)

I  need to know if I am considering that the gyro is working in 10Hz the total noise in each 0.1 seconds will be:

0.02º/0.1sec/sqrt(10)Hz = 0.063245553 º/s/sqrt(Hz).

I am undestanding that in each 0.1 second the expected noise will be 0.063245553º.

Applyng the equation for the angle random walk, that grows proportional to the square root of the time:

sigma_1 = 0.063245553º;
sigma(t) = sigma_1 * sqrt(t);

I am understanding that, for example, after 2 minutes the ARW will be:

t = (0.1 * 10) * 120 = 120 seconds

sigma(120) = 0.063245553º * sqrt(120)
sigma(120) = 0.692820321 º/sqrt(s)

Is this correct?

I am in doubt mainly because I understanding if I increase the frequency (Hz) the bias also increase:

1 Hz (1 sec) -> 0.02
10Hz (0.1 sec) -> 0.063245553

Thank you for any clarification.


texts: Ultrasonic HC-SR04 sensor, why does it even have a dead-zone of 2cm?

texts:
So I have a hard time understanding why the HC-SR04 has a dead-zone of 2 cm.
I understand why, the single-transducer ultrasonic distance sensors have a dead-zone, as they need to switching - But this is not the case with HC-SR04 as it both has a sending and receiving transducer.
Anyway, if this is due to the fact, that the wavelength of 40khz is around 0.8cm and that it needs to produce 8 full impulses (see the datasheet) - Shouldn't it then be 0.8*8 / 2 = 3.4cm?


texts: Does the frequency of a PWM signal have to be constant for a DC motor/fan speed control?

texts:
All PWM control systems I have seen for DC motor/fan speed control used a constant frequency. Is this really necessary in all cases?

How would the motor current have to be calculated for a PWM control with a constant or variable frequency?


texts: HC-06 (BT module) becomes un-responsive after ~20 minutes

texts:
I am seeing the following behavior on a HT-06 BT module (http://www.amazon.com/gp/product/B009DZQ4MG/ref=od_aui_detailpages00?ie=UTF8&psc=1) wired to an Arduino Uno.

The module works great for ~20m and then fails (the unit appears to shutdown - no lights are illuminated on the BT device). Arduino continues to run fine.

I am periodically querying the device from Python (PySerial) running on an OSX/MB through integrated bluetooth. Here is a log of the communication and you can see the failure after 20m.

[!] 2015-03-05 15:15:01.344719
[x] Finding device and service port
[x] Attempting connection: (30:14:12:19:26:86) on (1)
[x] Blocking on recv
[x] Closing socket
^@^@^@^@^@
[!] 2015-03-05 15:20:00.766638
[x] Finding device and service port
[x] Attempting connection: (30:14:12:19:26:86) on (1)
[x] Blocking on recv
[x] Closing socket
^@^@^@^@^@
[!] 2015-03-05 15:25:01.265796
[x] Finding device and service port
[x] Attempting connection: (30:14:12:19:26:86) on (1)
[x] Blocking on recv
[x] Closing socket
^@^@^@^@
[!] 2015-03-05 15:30:00.787703
[x] Finding device and service port
[x] Attempting connection: (30:14:12:19:26:86) on (1)
[x] Blocking on recv
[x] Closing socket
^@^@^@^@^@^@
[!] 2015-03-05 15:35:00.795710
[x] Finding device and service port
[x] Attempting connection: (30:14:12:19:26:86) on (1)
Traceback (most recent call last):
  File "/Users/test.py", line 28, in <module>
    raise serr
socket.error: [Errno -536870195] Cannot connect to 1 on 30:14:12:19:26:86
^@^@^@^@^@
[!] 2015-03-05 15:40:01.194140
[x] Finding device and service port
[x] Attempting connection: (30:14:12:19:26:86) on (1)
Traceback (most recent call last):
  File "/Users/test.py", line 28, in <module>
    raise serr
socket.error: [Errno -536870195] Cannot connect to 1 on 30:14:12:19:26:86
^@^@^@^@^@
[!] 2015-03-05 15:45:00.857675
[x] Finding device and service port
[x] Attempting connection: (30:14:12:19:26:86) on (1)
Traceback (most recent call last):
  File "/Users/test.py", line 28, in <module>
    raise serr
socket.error: [Errno -536870195] Cannot connect to 1 on 30:14:12:19:26:86

As you can see, once it fails, it never recovers. Anyone have ideas how to remedy this. I'll attempt to diagnose with another BT module (I have a few) to see if this is errant behavior of a bad device or an issue in my overall architecture.

TIA! (thanks in advance!)

UPDATE

It seems to have nothing to do with time and more to do with number of requests before failing. For example, I increased the frequency to run every 2minutes and you can see after 4x attempts the BT board fails:

[!] 2015-03-05 19:16:00.679951
[x] Finding device and service port
[x] Attempting connection: (30:14:10:14:11:85) on (1)
[x] Blocking on recv
[x] Closing socket
[x] Nothing consumed (0), exit
^@^@
[!] 2015-03-05 19:18:00.835225
[x] Finding device and service port
[x] Attempting connection: (30:14:10:14:11:85) on (1)
[x] Blocking on recv
[x] Closing socket
[x] Nothing consumed (0), exit
^@^@
[!] 2015-03-05 19:20:01.161330
[x] Finding device and service port
[x] Attempting connection: (30:14:10:14:11:85) on (1)
[x] Blocking on recv
[x] Closing socket
[x] Nothing consumed (0), exit
^@
[!] 2015-03-05 19:22:01.499951
[x] Finding device and service port
[x] Attempting connection: (30:14:10:14:11:85) on (1)
[x] Blocking on recv
[x] Closing socket
[x] Nothing consumed (0), exit
^@^@
[!] 2015-03-05 19:24:01.119598
[x] Finding device and service port
[x] Attempting connection: (30:14:10:14:11:85) on (1)
Traceback (most recent call last):
  File "/Users/test.py", line 28, in <module>
    raise serr
socket.timeout: connect timed out
^@/Library/Python/2.7/site-packages/lightblue/_lightblue.py:88: UserWarning: findservices() couldn't get services for : Timed out getting services for
  warnings.warn(msg)

Again, once it fails, it never will recover.


texts: How to interpret UJT Characteristics plot?

texts:
This is about understanding characteristics plot of a UJT:

I have read about UJTs but I have a problem understanding the following UJT characteristics plot:

This doesn't look like other plots of active elements I have seen so far. I will try to explain why and write down how I interpret it maybe it helps you to see where my logic is flawed.

I interpret that plot as follows:

I start by focusing on y-axis hence the emitter voltage Ve. My plan is to observe on the above plot how the emitter current Ie changes with respect to Ve. So I will see the relation as: Ie = f(Ve) where Ve is the variable.

So I increase the emitter voltage Ve i.e I go upwards on the y-axis. Until I reach up to Vp everything seems straightforward. Upto Vp because of the reverse bias very small current flows through E and B1.

But what is happening after this point? I cannot follow anymore. I can just say Increasing Ve further beyond Vp would forward bias the diode in equivalent circuit of the UJT. But Ve is not increasing on the plot anymore it is decreasing. I lose the feeling of Ie = f(Ve) relation. What kind of plot is this? It has two identical voltage values for a given current.

How is this plot obtained? My way of thinking was "increase Ve and see what happens to Ie" but Ve does not increase after Vp. Obviously something wrong in my way of thinking here.

How can we interpret this plot or how is this obtained? I'm really confused and feel stupid why I cannot get this.


texts: The importance of knowing that charges only occur in nature as integral multiples

texts:
So I read the following about electric charge from  Fundamentals of Electric Circuits (fifth edition) by Charles K. Alexander and Matthew N.O. Sadiku :

"According to experimental observations, the only charges that occur in nature are integral multiples of the electronic charge e = - 1.602 X 10^(-19) C"

Now I understand what is meant by the "the only charges that occur in nature are integral multiples " part - it means that the charges only exist as 1e, 2e or -1e; it cannot exist as 1/2 e, 0.8654e or πe etc.

What I don't understand is: what am I supposed to deduce by knowing that charge only exists as integral multiples? What would happen if the charges existed, for example, as 0.5e?


texts: How to extend a microcontroller GPIO to ~300 inputs?

texts:
I need to find out the address of buttons pushed. Say I need about 300 Input port required dedicated for individual buttons. Then I would need 300 I/O pins to read the address of a pushed button which is not feasible for Microcontroller without using any sort of Integrated Circuit.

My question is is there any IC that would dedicate an individual address for push button so whenever I push button it would send/give me an address like 0xA ? Or is there work around?


texts: compare half-bridge drivers IC for maximizing the quality/price

texts:
I selected a couple of Half-Bridge Drivers Gate for my BLDC project from well-known companies
they nearly have the same specifications for my Mosfets such as voltage operation and Temperature range
As I'm naturally interested to pick the lowest price however I think I should consider other parameters before select the final chip such as fall-raise time,dV/dt Immunity, Output Source / Sink Current Capability,....
is there any quality prioritize criteria that I should follow from top to bottom to select the specific IC before the jump to lower price


texts:
I am constructing 10kHz , 30kHz and 50kHz sine waves using wien bridge oscillator design with LM358 OP-Amp. I have a few problems with the circuits that i could not figure out. Thank you for all your helps.

1)The output sine waves are getting distorted as the frequency increases. It is OK for 10kHz but when i increase the frequency more to 30kHz or to 50kHz I am getting the following distortions on my waves. I have tried changing the Op-Amp, (not the model), changing the source changing the values for resistors but could not fix it.

2) And secondly I want to amplify the waves but non-inverting amplifier or inverting amplifier with only resistors aren't working. I've read the data sheet of LM-358 there is an example amplifier circuit for AC signals. However I couldn't figure out what component does what. Do I have to use that circuit or is there a simpler solution.

Again Thank you for all your kind help.


texts: A circularly polarized EM wave is perfectly absorbed by any interface?

texts:
According to the Fresnel equations, the effective reflectivity of an arbitrarily polarized electromagnetic wave is given as:
$$
\Gamma = \frac{\Gamma_p + \Gamma_s}{2} ,
$$
where \$\Gamma_p\$ and \$\Gamma_s\$ are the reflectivities for p and s polarization, respectively.
I assume the common scenario of an electromagnetic wave traveling through empty space (\$n_1=1; \epsilon_1=\epsilon_0, \mu_1=\mu_0\$) hitting a non-magnetic surface (\$\mu_2=\mu_0\$) with dielectric \$\epsilon_2=\epsilon_0 \epsilon_2'\$ (\$n_2=\sqrt{\epsilon_2'}\$) at a straight angle.
If I plug these into the Fresnel equations with an angle of incidence \$\theta_i=0\$, I obtain:
$$
\Gamma_p = \frac{\epsilon_2'-\sqrt{\epsilon_2'}}{\epsilon_2'+\sqrt{\epsilon_2'}} , \\
\Gamma_s = \frac{1-\sqrt{\epsilon_2'}}{1+\sqrt{\epsilon_2'}} .
$$
Then it is easy to see that \$\Gamma=(\Gamma_p+\Gamma_s)/2=0\$ ! This suggests that any circularly polarized wave hitting a surface at a perpendicular angle would be perfectly aborbed. That must be nonsense.
Where is the mistake?


texts:
I'm trying to build a remote control unit and want to 'remote' the antenna from the 433 MHz Tx unit. I'd appreciate some feedback before I order as my antenna/RF theory is sketchy and I want to know if there will be any effects.
My concept so far is this:
The 433 MHz unit sits on top of the PCB, attached by header pins at four points (VCC, Data, Gnd and Antenna). The Antenna trace goes a short distance through the VCC plane and above a GND plane. It then connects to a brass SMA and 1/4 wavelength antenna.

RF Tx Module:
http://www.energiazero.org/arduino_sensori/Complete%20Guide%20for%20RF%20433MHz%20Transmitter.pdf
SMA Connector:
https://uk.rs-online.com/web/p/coaxial-connectors/8861061/
433 MHz Antenna: https://uk.rs-online.com/web/p/rfid-antennas/7620030/

It's the same schematic as I used to prototype something which worked before. Only the layout is new. Image attached.


texts:
I am using a dual power supply model CPX200 from TTI in my school lab, and I am trying use it to supply 1.8V and 3.3V to a PCB, so I figured it was a good idea to check whether the ground of the dual port is coupled.

However, when I use multimeter DC voltage mode to measure the voltage difference between two ground terminal, it shows that the voltage difference is 0.3V and it starts decreasing slowly. I am having difficulties understanding this phenomenon.

So is the ground of dual power supply coupled? Why would my measurement decrease slowly?
Thanks a lot.


texts: Finding the necessary currents for AC analysis for CE NPN BJT amplifier

texts:
I have this circuit with a CE NPN-BJT amplifier and I am struggling to find the necessary values for calculating r(pi) for AC analysis, i.e. the hybrid-pi model:

$$r_{pi} = \frac{V_{thermal}}{I_b}$$

I need to find the current going into the base of the CE amplifier. I am assuming that the infinite capacitance to be short circuited in the DC analysis. This means that V(b) = 0 I can then use the active region model of NPN BJT for DC analysis to write down the KVL which gives me something like this: -0.7 - 60(I[e]) = 0

I solve the equation and end up with a negative emitter current. This does not adhere to the model. What am I doing wrong?

[


texts: is it possible to replace the metal on the bottom of a PCB?

texts: I attempted to drill three holes slightly bigger on a circuit board. As soon as I touched the board with the drill, the metal that you solder contacts to separated from the board. I want to know if there is a way to repair the board.


texts: IMU sensor suddenly outputs only a fixed value

texts:
Description of the situation
I am calculating the angle using BMI 160.
Intermittently, the sensor's value is fixed.
I've tested it in certain situations, but each of them happens in a different test situation.
The test method rotated the sensor several times at the same angle as when the sensor failed, but did not occur.
I use the data from the sensor only with outputData * (9.8 / 16384) operations.
My Setting

OS : Ubuntu 18.04 LTS
IDE : MPLAB X IDE v5.30
Dugger Tool : PICKIT 3
Sensor : Bosch BMI 160
MCU : dsPIC33EV128

Question
I have two questions.

Do these malfunctions occur frequently in IMU sensors?

Do you need a separate algorithm to use the sensor?

Resources
PICkit™ 3 In-Circuit Debugger : https://www.microchip.com/Developmenttools/ProductDetails/PG164130
dsPIC33EV 5V CAN-LIN STARTER KIT : https://www.microchip.com/DevelopmentTools/ProductDetails/dm330018
Bosch BMI 160 :
https://www.bosch-sensortec.com/products/motion-sensors/imus/bmi160.html


texts: It takes a certain time for current to reach it's maximum value(i.e steady state at 99% or 100%), and that times is(to my knowledge) determined by the value of inductance(L) and resistance(R) of a conductor. If a superconductor is used instead of a normal conductor(like copper), how would things change? If we assume R=0. And since some superconductors have quite low inductance due to their small diameters,example.


texts: Current Output for ZVS Flyback Transformer

texts:
What is the typical current output for high voltage of ZVS flyback transformer or how to properly measure it?

Update with the schematic, the fly-back transformer is typical one used in old CRT TV;


texts: What's the LC filter arrangement on dual output DC/DC converters?

texts:
It's pretty hard to find a filter arrangement for a dual output converter, but I came across the following:-

Taken from here.

So for the bottom example, is the LC arrangement correct?  I always thought that a -ve voltage flowed into the 0V terminal.  That would imply that the lower filter should be the other way around, with the capacitor put adjacent to the converter, and the inductor away from it.  That way the current flows firstly though the inductor and then past the capacitor, as it does in the +ve configuration above the 0V rail.

Am I wrong?


texts: What are the things to notice before actually connecting a PWM motor circuit?

texts:
I have simulated a PWM motor control circuit in Proteus, now I want to bring it to life and connect a circuit in real world.

Here's my PWM circuit in Proteus:

And the code:

unsigned int duty_50;

void main(){
      ADPCFG = 0xFFFF;// initialize AN pins as digital
      PORTB  = 0x01;
      TRISB  = 0;     // initialize portb as output

      duty_50 = PWM1_MC_Init(5000, 0, 0x01, 0); // Pwm_Mc_Init returns 50% of the duty

      PWM1_MC_Set_Duty(duty_50, 1);
      PWM1_MC_Start();

      while(1);
}

In simulation, this circuit works fine,

And I already bought the components I need:

1.dsPIC

2.L293D driver IC

3.DC Motor(Which needs 1.5V and 120 mA)

4.board

I want to use these components and power supply machine to connect these components in real world, but I don't know if there might be problems. Is there something I should pay attention to before connect the real circuit so that I won't make some mistakes and burn some components?


texts: Does nodal analysis work with alternating currents if every step is treated like DC?

texts:
I have a question that is difficult for me to describe.

I want to know if I will get accurate readings of an AC circuit by nodal analysis if I treat each significant voltage change as a DC circuit.

For example: if I have a 10 volt AC power supply at 60 hz, can I determine the currents (through a complex circuit) if I calculate each separate voltage up to my target point as a DC voltage?

Will I get approximately accurate results?


texts: NodeMCU 12E: Using 8 Digital pins 8 Channel Relay

texts:
I am trying to connect my 8 Channel Relay to my NodeMCU 12E and use it for automation with Alexa.

For digital output I am using the ports:
D0,D1,D2,D4,D5,D6,D7,D8

And for power:

Relay(VCC) -> Board Vin

Relay(GND) -> Board GND

This is being powered by a micro USB cable coming from my computer.

After uploading, the code works properly.
When i disconnect and reconnect the power cable the code just doesn't work-unless i take out the GND and Vin wires before connecting the power cable and then plug both back in.

After online research I was recommended not to use D3, D4, D8, so how can I get 8 ports to connect to my relay?

Relay:

NodeMCU 12E:


texts: Infineon PMIC I2C connection for first programming

texts:
I want to use the Infineon IRPS5401, a Power Management IC with PMBUS functionality through the I2C protocol. Infineon suggests using the USB005 dongle https://www.infineon.com/dgdl/ug-usb005.pdf?fileId=5546d462533600a40153568485d32985
for programming purposes with the PowIRCenter software.
The dongle is this:

(image from dongle's datasheet)

The PMIC programming guide describes the configuration circuit with all the hardware settings and connections for programming the PMIC:

I want to build a custom PCB for the first programming of the IRPS5401 so if I understand correctly I must use the indicated circuit with the usb005 dongle from Infineon connected to the I2C Data and I2C Clock pins (and GND obviously).

(Image from IRPS5401 datasheet with CLK, DATA, and VDDIO pins descriptions)

My problems are two:

The 5V depicted for the sleep and Vcc pins.
The 3.3/5 Vdc depicted for the Vddio pin and pull-up of SDA and SCL.

As I see from the first image, the dongle has 3 pins: GND, SDA, and SCL and hence I can't derive the I2C master voltage from it.

Do I need to plan in my custom-PCB an independent 3.3V for pull-up of I2C data and clock and VDDIO or a 5V?

I think that this depends on the voltage level of the I2C master but the dongle's documentation doesn't have much information about it.


texts: Data Sheet Interpretation - "Insulation Area" and mystery Symbol

texts:
While creating a (my first) device package for this Micro SD socket in CadSoft EAGLE
I stumbled over the inclusion of an "insulation area" in the recommended pcb layout:

I'm guessing this is supposed to prevent the contact springs from contacting any tracks under the socket. There are holes on the bottom through which this could conceivably happen.

Am I right in my assumption?
Is there something I should do to the layout in that area or will the solder resist suffice?
What does the Symbol in the green box mean?


texts: How can I create the characteristic warp core sound?

texts:
I'm trying to build a miniature warp core (purely decorative, not functional) with the main element being an LED chaser circuit with 10 LEDs. I'm planning on using a 555 timer and a 4017 decade counter like described in many examples one can find on the internet for LED chaser circuits (example).

Now I had the idea that the miniature warp core would be much more impressive if it actually produced the typical warp core sound while it is active, synchronized to the chasing LEDs.

The sound would not have to be the exact sound of course, any oscillating low humming that could conceivable be caused by the engine of a starship would do. Unfortunately my experience with building electronic circuits is extremely limited, so I'm not sure how to produce such a sound. In my naive understanding it could work e.g. by creating a low base sound using another 555 and then somehow use the signal from the 555 driving the LEDs to modify the base sound.


texts: Reset the timer counter before the overflow in ATXMEGA64a1

texts:
I want to reset the timer before the timer interrupt.

In my case, I will use the Mod bus protocol for serial port. I had to reset the timer for each byte sent and send data if the timer reach 3.5 ts(Time for sending byte). It mean if we didn't receive any byte until (3.5ts s ) we send data, if not, we add new data in the buffer.

So in this case, I want to use two interrupts:

One interrupt for the serial port Rx. In this interrupt I will reset the timer.
One interrupt for the Timer where I will send the Buffer.


texts:
I am facing some difficulty getting a 1EDN7512B driver from Infineon to trigger at all. The following is one of the simple test circuits I quickly threw on a breadboard to test, with no success. I am using a jumper wire to trigger at the IN+ from the 12V rail. I tried triggering an IRF840 (shown as IRF740 in schematic) with a simple current limited LED to test the output. I also tried triggering an Infineon CoolMOS MOSFET (specifically the IPL60R065P7), basically in the same circuit set-up, to no avail. I tried changing the driver, thinking maybe I fried this one. I tried with and without gate resistor. Same result. MOSFETs tested are ok since I can trigger them with a direct connection from 12V to gate.

This leads me to believe that I, very much new to electronics (this is a hobby), am missing something either obvious or basic. Why is this test circuit not working?

Breadboard: The 1EDN7512B is soldered onto a homemade breakout board. The breakout board has a trace connecting GND and IN0, which I cut and added a jumper (red) to GND (pin 2) to further test having IN- at different logic levels. To trigger IN+, I connect the blue jumper from IN+ to 12V directly.

The breakout board: the red indicates the modification I did to breakout GND and IN- separately.

Update 1

I soldered a new driver chip onto a breakout board and tried it step by step. I first connected 12V power to it, then, using a 3.3V source (a NodeMCU) triggered the IN+ and measured the voltage between GND and OUT. It worked as expected, outputting 12V on OUT when IN+ was HIGH (3.3V) and 0V when IN+ was floating/disconnected. I then reconnected the MOSFET with the same setup as before (LED + resistor using the same 12V power), only I didn't have a resistor between OUT and the MOSFET gate. I then triggered the driver. It worked for a few times (~5) then suddenly stopped. It now behaves like the previous 3 chips. There is a somewhat fluctuating voltage on OUT in the 0-0.1V range, regardless of state of IN+.

Context: I am just testing the driver to later on use it for trailing-edge phase-cutting, using two MOSFETS in the following configuration:
The driver's output is connected to the gates of both MOSFETS, which are switching mains to control dimming of lights. The input in this case will be essentially a 50Hz PWM signal from a microcontroller (ESP8266 or similar).


texts: Closed loop control of PWM using current sensing method

texts:
This is the block diagram of the project i am working on. I have a DC voltage range of input as 8V to 16V.
The duty cycle at the PWM generation should change automatically from 10% to 90%. I require 1A current constantly to the load despite change in duty cycle of PWM signal. For this purpose, the current sense and control block is used in feedback where I prefer using shunt resistor method. The driver to drive the load I want to use is a MOSFET. The load let us assume is purely resistive and not inductive.

Please help me know on how should I go forward with it. Which method should I use to generate PWM waveform? What MOSFET should i use such that it withstands a little more than 1A current, and how should I design the resistance value of current sensing resistor?


texts:
I want to know what is different between voltage reference and virtual ground and can you use both of it as rail-splitter in transimpedance amplifier, if not why.
All I know is Virtual ground chips like TL2426 have an opamp buffer at the output, but the main issue if supply voltage changes the output change too due to voltage divider.
Below part number is connect just for demonstration(actual opamp pn is mcp6v02)


texts:
What is the difference between level shifter, voltage regulator and dc-dc converter?

My understanding is:

level shifter is used to convert one voltage into another voltage
voltage regulator is used to produce constant output voltage from high voltage
dc-dc converter is used to convert dc level into different level

Is this correct?

If I want to convert 5V voltage supply to 2.5V, do I need to use regulator, level shifter or dc-dc converter?


texts:
I am planning to work with this N-mosfet - SiSA72DN

Max ratings:

Specs:

Does this mean: I need to apply a voltage > 2.4 V on the gate to turn it on fully and the applied voltage must be < 20 V?

Application - Switching 5 V and 24 V loads.

Confirmation: Will the following schematic work for switching both 5V and 24V? Is there any improvement I can make to this circuit?

Note - 3.3 V will be provided by a GPIO.

simulate this circuit – Schematic created using CircuitLab


texts: Analyzing an op amp circuit (transfer function) that does not match the basic cases

texts:
At the following circuit I want to find what it does and basically its transfer function. I've searched a lot but I didn't find any circuit like this. Since it does not match any of the basic types of op amp circuits (inverting or non-inverting amplifier) I don't know where to start from. Finally, anyone knows what's the name of this circuit? Please note that this is not homework.

Following Lorenzo Donati's method I got to this point for the transfer function:


texts:
When we model electric field as something that represents the "flow" of something that is conserved, we can prove that the flux due to a single point charge, through the following surface,

Flux through a radial surface

is effectively zero. And therefore prove (almost) that flux through all kinds of  surfaces that do not include a charge is zero. But when we do have a charge, we perform a clever trick, we enclose the charge with another surface, in the following manner,

Flux due to point charge

and therefore prove that the flux through the required surface is equal to the flux through small surface enclosing the charge.
Therefore,

$$ \int_S \mathbf E . \mathbf {ds} = \dfrac{q}{4\pi \epsilon r^2} (4\pi r^2) \\ \int_S \mathbf E . \mathbf {ds} = \dfrac{q}{ \epsilon}
 $$

This "trick" was possible, only because,  we had a point charge and the field was radially outward. So my question is, how are we able to generalise that the flux through any surface is equal to this fraction \$\dfrac{q}{\epsilon}\$? What if we had two point charges instead of one, then we wouldn't get a convenient \$4\pi r^2\$ term. I'm relatively new to the subject, so I'm missing something obvious. This again leads to a question; why in the first place, is there a \$4\pi\$  in Coulomb's law?


texts: What relay is suitable for a submersible water pump

texts:
I have an AC submersible water pump with the following ratings:

Voltage: 165v-250v/50Hz
Power 18W
H-max 1.8 meters
Output: 1200L/h

My mains voltage is 225V to 250V

I need the specs of a relay ( 9v DC to AC ) for this. From the pump specs, I am thinking the current required would be  I = 18/250v, which is 72 milliamperes (hope I am right).  Please suggest a good relay for this.  I already have a Songle relay shield (see pic)

with the following rating

5v DC
10 A 250v ac 10A 125V ac
10 A 30 v DC 10A 30V DC

Although it's not a 9V DC, I still wanted to know if that would work.


texts: What load can i connect if data sheet is missing output voltage

texts:
I am looking at a DC to DC converter data sheet that has an input voltage of 0V-100V. The datasheet only mentions a max output current of 4 amps. Is it safe to assume I can place a load of any voltage as long as it is lower than my input voltage, and draws less than 4 amps?

I have attached the data sheet for reference. Converter Data Sheet


texts: Where can I find 1.5kWh energy, at about 5-15Wh/kg batteries that can deliver about 350kW power? (as indicated on this wikipedia article?)

texts:
I am a rookie in this field, so any kind of feedback/edit is welcome! :)

I am currently trying to find supercapacitors/batteries that have following properties:

Have about 1.5kWh energy, at about 5-15Wh/kg (assuming we can stack these up to about 150kg of batteries/supercaps).
The power delivered must be about 350kW, so a little more than 2kW/kg.

I have read on wikipedia that they exist: as indicated here, but I can't find these (with the respective power densities). What type of supercapacitors are these and where could I possibly contact someone who knows about this stuff? (a company selling those might be useful I guess?).

Additionally, it would be great if these could operate in near-vacuum (800-1600Pascal), but I realise that this sounds unreasonable, but I would be really grateful if you could provide me with information :)


texts:
Which value of \$\omega_0\$ would you choose for the following transfer function to eliminate the 60 Hz component of a signal?

$$
  H(e^{j\omega}) = \frac{[1-e^{-j(\omega - \omega_0)}][1-e^{-j(\omega + \omega_0)}]}
  {[1-0.9e^{-j(\omega - \omega_0)}][1-0.9e^{-j(\omega + \omega_0)}]}
$$


texts:
I am using an AD7323 12bit+sign 4-channel ADC an on a custom Arduino shield.
I drive it with 12V from a power supply and -12V created using an ICL7662 IC. VCC is 5V from the Arduino.
The ADC is used to measure DC signals with a low sampling rate (sampling once every second or so).

The board layout looks like this

and the AD7323 pinout is

I am using ceramic smd capacitors and BAT43 diodes.
Using the control register, I set Power Mode to Normal (0,0), Converter Mode Single-Ended (0,0), Coding 1 (straight-binary), internal reference 1, and sequencer mode disabled (0,0).

SPI is configured at 256000 speed and MODE2. I first write a the address to the control register, and then write 0 via SPI to receive the next conversion value, which gives me -FSR/2+1LSB = 0 and FSR/2-1LSB = 8191 as a value.

The relevant C++ code is

void AD7323::SetSamplingChannel(uint16_t channel) {
    uint16_t data = GetControlValue(true);
    data &= ~(3 << 10); //Clear channel bytes
    data |= channel << 10; // Push channel address
    uint16_t answer = WriteSPI(data);
}

uint16_t AD7323::ReadADC(uint16_t channel)
{
    SetSamplingChannel(channel);
    uint16_t answer = WriteSPI(0) & ~(57344); //Remove top 3 bits
    return answer;
}
// Get the current value of for the control register
uint16_t AD7323::GetControlValue(bool Write) {

    uint16_t data = Write ? 32800 : 32; //Sets write bit and Coding
    data &= ~(3 << 8); //Mode 0,0
    data |= Mode << 8; //Set new mode
    data &= ~(1 << 4); //Ref 0
    data |= (RefEnabled ? 1 : 0) << 4; //Set ref
    data &= ~(3 << 6); //Power mode 0,0
    data |= PowerMode << 6; //Set power mode
    return data;
}
uint16_t AD7323::WriteSPI(uint16_t DIN)
{
  SPI.beginTransaction(settings); //settings = SPISettings(256000, MSBFIRST, SPI_MODE2);
  digitalWrite(CSPin,LOW);
  uint16_t val = SPI.transfer16(DIN);
  digitalWrite(CSPin,HIGH);
  SPI.endTransaction();
  delay(1); //Just for testing purposes
  return val;
}

This basically works, however when I simply apply a given voltage and read the ADC value, I have a constant offset of 11-13 LSB (LSB=2.441 mV at -10->10V range).

I am wondering if I have done anything wrong on the layout of code side of things. I was a bit on the low side in terms of decoupling caps for the chip, but I don't understand how missing decoupling caps could cause a constant offset in the value read.
Also, should this be taken care of by the internal 2.5V reference in the ADC?

Or is this just a thing that exists, so that I have to add a calibration function in the code?

Since I am out of ideas, I would be glad for any input. Let me know if you need more information.


texts: 12v circuit with push button needs to auto press and hold

texts:
I need to create a circuit which closes a relay for 10 seconds (activates an external circuit by completing it (the same as if I fit a push button) and then releases the relay for 1 second, before making it again for 10 - and repeats forever.

Any advise on what components (etc) to use here, would be fantastic.


texts: Using 25 IR LEDs with Raspberry Pi and Transistor

texts:
Using a Raspberry Pi and 5V I want to use 25 IR LEDs (5mm LED, 940nm wavelength, 20 degree beam width, 100 mA continuous, 1000 mA pulse, Approx 1.6V forward voltage; http://www.exp-tech.de/super-bright-5mm-ir-led-25-pack) in parallel using 8 pairs of 3 LEDs each pair with a 2 ohm resistor and one single LED with a 36 ohm resistor.

This tutorial is my basis:
https://www.sparkfun.com/news/1396

You can see that in this tutorial a npn transistor is used with a resistor R6 of 330 ohm.

I've ordered this PN2222 transistor (http://www.exp-tech.de/npn-bipolar-transistors-pn2222-10-pack).

My question is, once I have all LEDs and their resistors (2 and 36 ohm) in place, how would I need to install the transistor(s) and how would I calculate the R6 resistor for my example?

Update 1:
Here is the LED datahseet: http://www.adafruit.com/datasheets/IR333_A_datasheet.pdf
They are just turning on/off all at once.
For my project I would need to get enough IR light in order to brighten up a whole room of 15 and up to 35 square meters, if less LEDs will produce enough IR light, I'm happy with it.
For video recording a Raspberry Pi NoIR Camera will be used.
The system will be time-controlled, the LEDs are supposed to run probably 4-5 hours for each time-frame.
@KyranF: You're right that I was not aware fo this as this is acutally my first project including more than one LED.

Here is a first try to visualize the solution.

Does this setup with the mentioned LEDs and a MOSFET sense?
Do you think 14 LEDs of this kind would be enough in order to brighten up a whole room?

Update 2:
This is my current set-up, which seems to be wrong as well.
I'm not getting the IR LEDs to lighten up.

Important hint: I'm using 33 ohm resistors for the LEDs as the LEDs I've finally bought are using 50mA instead of 100mA as the ones listed before. Here is the new Datasheet

My Python code looks like this:

import RPi.GPIO as GPIO ## Import GPIO library
import time ## Import 'time' library. Allows us to use 'sleep'
GPIO.setmode(GPIO.BOARD) ## Use board pin numbering
GPIO.setup(7, GPIO.OUT) ## Setup GPIO 4 Pin 7 to OUT
GPIO.output(7,True) ## Turn on GPIO 4 pin 7
time.sleep(5)## Wait
GPIO.output(7,False)## Switch off pin 7

The wiring looks like this:

Here is an overview of the GPIO setup:


texts: I made a personal count down timer with PIC16F628A and two multiplexed  seven segment LEDs. The system was tested on breadboard at 5 volts USB . However, I intend to work them on batteries at low power consumption. Is it advisable to power the whole system by 3 volts by AA batteries ?


texts: ESP8266-01 automatic upload and run (without manually toggle GPIO0 to GND)

texts:
I bought one of the cheap ESP8266-01 module and I have succesfully load sketch using Arduino IDE. Module is great (in 5 minutes I have a working simple web server) but I found a little bit tricky switching between programming mode/running mode. In details:

To upload firmware

power off module
connect GPIO_0 to GND
turn power on and upload from Arduino IDE

To run sketch after upload

power off module again
remove bridge GPIO_0-GND
power on again

When you develop and made frequent firmware uploads, this process become very tedious. So I want to ask: is there any way to automate the process with custom circuit?

Like Arduino board which when upload start it perfom it automatically then reset the board and run sketch.


texts: Classification of logic hazards in combinatorial networks

texts:
I've got a doubt about the classification of logic hazards in combinatorial networks I could not dissipate searching the net.

What I know is that:

a static hazard happens when an input transition which should not trigger an output transition makes the output change momentarily, i.e. it generates a single spurious pulse;

a dynamic hazard happens when an input transition which should trigger an output transition makes the output oscillate before it settles to the new state.

I have trouble classifying this case: the input transition shouldn't produce any output transitions, but it produces more than one spurious pulse, i.e. the output oscillates for a while before returning to its original state.

Is this a case of static or dynamic hazard? According to some definitions it seems it should be classified as static because the output is not intended to change. According to other ones it should be a dynamic hazard because it produces an oscillation (more than two output transitions).

I'm inclined to classify this case as dynamic, since the output changes more than two times, but many definitions I found on the Internet stress the fact that a dynamic hazard happens when the output oscillates before settling to a new state.

Have I got it wrong? What am I missing? Any explanation and/or pointers to authoritative sources for a clearer definition is appreciated.


texts: How are electric under blankets fail safe?

texts:
Electric under blankets are mains powered and yet you lie on them.  240V in the UK. They appear to effectively be a single resistive heating element. Clearly they're not earthed as that would be difficult, and I can't see how double insulation could apply.

It seems to me that if the element breaks, it could poke through the material and cause a shock hazard to the sleeper.  And what if my old dog wees on it, or bites it?  If they were a danger, they wouldn't be sold.  So how are they made fail safe?


texts: How do I wire this AC motor to a UK plug?

texts: When wiring this 220V, 60rpm AC motor to the mains, it turns perfectly with the live and neutral wires connected to terminals 1 and 2 and with the earth wire disconnected from terminal 3, however it does not turn when the earth wire is connected to terminal 3. The seller indicates that the live and neutral wires are to be connected to these terminals, but does not mention the earth wire, or the purpose of the third terminal. How do I resolve this when wiring it to UK mains?


texts: Does Transformer heating add noise to a circuit?

texts:
I have a circuit on PCB with a transformer that generates a lot of heat.

It is actually an energy meter, and I'm getting increasing error as time goes on.
I observe that the transformer heats up considerably, and I was wondering if this can increase the noise in the circuit, and if so, by how much.

EDIT:
I made some measurements on the power supply:

Input Ac voltage: 220VAC

Voltage at the transformer secondary (with bridge rectifier disconnected): 19VAC

Voltage at the transformer secondary (with bridge rectifier and the rest of the power supply connected): 9VAC

Current after bridge: 220mA

Current at the end of the power supply entering the main circuit (from the point where you see the +sign on the schematic): 10mA

Someone suggested I put a resistor after the bridge to limit the current, saying it was way too high. I need some input here please.

One more thing, can anyone tell me the function of 130Ω R7 resistor between the two capacitors just after the zener diode?


texts: Identify Vintage Power Cord for 1980s Organ

texts:
I Recently acquired a Technics SX-C600 organ but it needs a power cord. Does anyone know what type of power cord I should get for this?
My understanding is that this is a rare organ.


texts: Can we use tvs and mov together for thruster?

texts:
I want to know if we can use both tvs and mov varistor together ?

What will be good for thrusters ?
And placement between esc and thruster or before esc?

Update:

system voltage is power supply 48 volt then 2 buck converters then arduino and thrusters ( motor with propeller ) . I wanna protect arduino , converters from surge current and clamp voltages


texts:
I am trying to figure out if I implemented a 2-1 Mux correctly based on  a 3 variable K-map.

my function states F(x,y,z)=  Σm(0,1,3,6), and I have created a kmap as follows

  00  01  11 10

0]     1  ,  0,  1 , 0

1]     1 , 1 , 0 , 0

Note: the most sig bit is x,and xy are the top inputs and z is the side inputs

from this I found that a 2-1 Mux could be implemented by using z as my selector and ~b=0 and ~a=1, as my inputs to be pushed.
Is this correct or have I done this wrong?


texts: Why does my DIY Barebones Arduino Due with SAM3x8E overheat on RESET press?

texts:
I made my own diy "bare bones" Arduino Due in an embedded application. Basically I was making a portable Bluetooth headphone amplifier for a school project. The point of the MCU was to display battery information on a touchscreen LCD and to control volume with a digital resistor. Everything else on my board seems to work including Bluetooth. Since this was a prototype, I added a switch which would bypass the digital resistor and go to a normal pot for volume control, so I know everything on my board works except the SAM3x8E.

Here is the issue:

When I plug in the USB, the device does not get recognized by the PC at all. No COM ports are available in device manager. If I press the reset button, the chip gets abnormally hot. Uncomfortably hot to the touch! If you unplug power and plug it back in, even after waiting a second or two, it STILL starts getting hot. It's only after you power cycle and hit the ERASE button a few times that the chip finally stops overheating. Also, during this process, my 3v regulator drops out as if the chip is drawing too much current. (because the blue 3.3v led goes out)

After the power cycle, things go back to normal, and Bluetooth and the rest of my amplifier works fine. Can anyone take a look at my schematic and see if anything obvious is wrong? I am a little lost, any suggestions to help diagnose this issue?

Tomorrow, I will hook it up to an oscilloscope to make sure my crystals are providing clock. Any other test I can perform? I have triple checked this schematic against a number of Arduino Due and SAM3x8E reference schematics and do not see anything obviously wrong.

Here are the Eagle Cad Files:

Eagle Schematic File

Eagle Board File

Also some photos:

Here is the actual board (don't mind the unsightly makeshift jumpers):

Also, here is a schematic of the Power circuit:


texts: IT characteristic implementation of motor protection circuit

texts:
I am trying to implement The IT - characteristic feature for motor protection device.There are 2C,5C,10C curve feature . can someone suggest me how it can be implemented in C code.

Is there any example code available.

1) what is effect of current setting on above curve based on 2.5C/5C/10C curve
2) Is there any equation available for time Vs current

Setting current as below

 under current limit  0.2 -25A
 overload current limit 0.2 -25A
 Short circuit limit   0.2A -50A
 Locked Rotor current limit 0.2A-50A

I find solution for IT characteristic.  this sample example given here. need c code

assume Overload current = 10A(user defined setting)

Over load current trip time =10s(user defined setting)

if curve 2C is selected

calculation are as below   The relay should turn on 30% over load trip time i.e 13A

Trip_Time  over_current
10  10
9   10.3
8   10.6
7   10.9
6   11.2
5   11.5
4   11.8
3   12.1
2   12.4
1   12.7
0   13

in code if the Nominal current exceeds overload current these are trip timing for relay. The timing and current will change as per user defined setting. can some one guide me C code.


texts:
Usually I notice that power adapters get warm whether they are being used to power a device or not.

The rectangular Dell computer power adapters, however, do not seem to get warm unless they are plugged into a laptop. Is that because they have a switch or something inside of them to turn them off unless there is a load, or is there some other reason?


texts: 555 not working as expected at high frequency

texts:
Both test in real life and simulation.
Target waveform: 2MHz at 99% duty cycle, but when the frequency has increased to 2MHz, the duty cycle drops to near 65%. What is the cause for this problem here?
Good result as expected:

Bad result:


texts: VFD Power Savings physical explanation - cubic vs square relationship

texts:
I am trying to either explain or derive where the power savings come from with a variable frequency drive (VFD). I am well aware of all the literature and generally accepted assumption that energy savings resulting from a VFD are proportional to the cube of the ratio of the reduced speed to the original speed of the motor. This is from the affinity laws.

However, if I consider the rotational power equation where power is equal to torque multiplied by rotational velocity OR the fluid power equation where power is equal to pressure multiplied by flow rate, it would appear to me that power should be directly proportional to speed.

Or, if I consider that VFDs maintain a constant volts to hertz ratio and assume that motor current is proportional to load and then use the electrical power equation where power equals current multiplied by voltage multiplied by power factor - I would assume that power is proportional to the square of the ratio of the reduced speed to the original speed.

Can anyone clarify things? Where is the discrepancy or what am I missing here?
And are the affinity laws just stated as fact? Are they fundamental principles or do they have a derivation relating to fluid flow.

I will update this question with equations to make it easier to read.

Any thoughts or explanations are greatly appreciated!

Thanks!


texts: Variable (Freq. and Voltage) AC Power Supply

texts:
I am working on project called "Polarization Modulator". Idea is the having sinusoidal current on the inductor.(100uH) Frequency ( 500Hz - 2500Hz ) and current (peak current) (0A - 10A) on the inductor should be adjustable. I have 28V power supply only. I tried to use H - Bridge with NMOS but it has some problems.
Hardest point for this project is @2500 Hz. @2500Hz ZL = 1.57Ohm. In order to get 10A peak, i need at least 17VAC. So, frequency changes mean VAC changes.
Lower frequency >> @Constant VAC >> Higher Peak Current

In summary;
28VDC to adjustable frequency and AC Voltage Converter that can give at least 10A peak current.

Is that resolvable ? Worth to start on this project ?
Any different ideas are welcome

( I newly graduated from university )

I have
Adjustable sine wave generator (0V - 1V) (1Hz - 5Mhz )

Thank you


texts: Banana connector confusion [Male and Female?]

texts:
I recently bought few pairs(male and female(that's what I asked for)) of banana connectors for my home project. I didn't check what the storekeeper gave me because I never had any complains with what he handed me. And I guess that's the mistake I did probably.
Here's a picture of what I got.

Every pair had black and white ones.
I tried inserting the metal of one into the hole of another but the connection is pretty loose.
Does this kind of pair exist as a banana connector pair or is it the case of wrong delivery from the store-keeper?
And finally, is there any way to work with these connectors. I can't get outside due to the shutdown in my area.


texts: LM358 OPAMP non inverting amplifier DC errors

texts:
Trying to amplify IR sensor 40mV DC output using LM358 noninverting amplifier circuit.

Selected resistance as R1 2.2K and feedback resistance, R2 51K. Got output voltage 0.8V. Measured output voltage by changing resistance values R1 to 1K and R2 to upto 1M, but output voltage didn't get above 0.8V. Supply voltage of opamp is 5V.
How can I get the output voltage of opamp above 1.5V?


texts: How do commercial microprocessors meet timing with a gigahertz clock?

texts:
I am having troubles making a relatively simple FPGA design (for an Altera Cyclone IV) meet timing for logic driven by a 250 MHz clock. This makes me wonder how commercial microprocessors (such as the Intel Core i7) manage to meet timing at clock frequencies more than an order of magnitude higher.

How can commercial microprocessors meet timing at 3.8 GHz when I'm struggling at 250 MHz for an FPGA?


texts:
simulate this circuit – Schematic created using CircuitLab

What would the voltage across the resistor be? What would its polarity be? I don't see anyway for KVL to not be violated.


texts: Potentiometer value goes up and then down again

texts:
I have 16 potentiometers of the same value (with some tolerance) like this. The wipers go to muxers and then to ADC pins of a micro-controller.

On the breadboard this worked fine (using only a few potentiometers), but now that I soldered it together and testing each pot, 2 pots in the middle behave weird. When I disconnect the circuit from power and use a multimeter to measure their resistor value while dialing from min to max, then the value goes up for a while and then all of a sudden goes down again. It never reaches 4.7k at all.

Since I am not an electronic engineer, I wonder if I just managed to buy some broken pots or if I did something stupid here (in which case buying new pots and swapping them won't help).


texts: Can I use steelwool for soldering iron cleaning

texts:
Wondering should I use steel wool for cleaning my soldering iron tip.
Is it bad?
Will it impact my tip?
Will it clean the black oxidization off?


texts: Do 3G and phone calls(gsm) use the same antenna in a mobile phone?

texts:
When I disable "3G or EDGE" (cellular data) connection from my smart phone's settings, I can still make a phone call.

Do phone calls and cellular data use different antennas and frequencies in a mobile phone?  Or it is just an inner arrangement?

I mean do the cellular voice and data networks use different antennas?


texts: USB: what are the advantages (or disadvantages) or using HID over serial-over-USB?

texts:
Disclaimer: I'm a novice at electronics and even more so to working with USB, please bear with me if I misunderstand some of the essentials behind how USB works. Any correction welcome!

The scenario: with a group of friends we are building a robotic sailing boat. We are managing all the on-board sensors through a µC (AVR) but the sailing AI is done on an embedded linux system. The electronics is connected to the the AI hardware via USB, and I am looking for advice on what protocol to use for the transmission.

We already tried both the serial-over-USB and using HID, and both worked good enough™ in our short, near-coast tests but before settling for one or the other, I'd like to know if there is some non-trivial but nevertheless important differences between the two that I missed to consider. For our project the most important characteristics are:

Reliability: our robot is due to sail autonomously for a few days. Is either
of the two protocol inherently "safer" / with better error handling /
self-recovery functionality?
Throughput: although in normal operating situations our throughput could
well be under 1Kb/s, under certain conditions we will need to harvest data
nearly real-time. Serial is limited to 115Kb/s, does HID have a speed limit
other than the 1500Kb/s of the USB 1.0 protocol?

...but as I said: I'm pretty new to electronics/USB, so if you feel I am missing a key parameter, I'll be glad to hear.

Thanks in advance for your time and expertise!


texts: Is there any problem with these TSL201R IC's?

texts:
I ordered two TSL201R DIP-8 on a chinese website, which I thought should look like this :

However, I received these two guys :

As hobbyist I've never seen this kind of IC's before, so is it a kind of protective wrapper, or just a scam (or anything else) ?

Thank you !


texts:
How to measure frequency of sine wave using pic microcontroller? I found the article on this website
http://microcontrollerslab.com/sine-wave-frequency-measurement-using-pic/
But I didn't understand code. Anyone can help me to understand code on this website?


texts: Resolution a problem with voltage divider

texts:
I'm facing a problem I don't exactly know how to resolve.

I have this circuit

The 2k resistance is a potentiometer. Basically we have a wheatstone bridge.
Here's the picture

The question is : how do you adjust the potentiometer so that the amp meter shows a 0 current.

Well, the answer should be that - and only with reasoning on how the resistances on the two vertical branches (the lower/upper part of the potentiometer) act as a tension divider, or at least that's how they did it in my solution book - the upper part (say X) and lower part (say Y) of the potentiometer should make it so that X/Y = 8,2/3.

Seriously I don't get it. I have tried methods using superposition principle (considering for example X in serial with Req(Y+3k), and 8,2 in serial with Req(Y+3k)), but I end up with X = 8,2k which is non sense since the potentiometer is 2k.

Can someone explain? I know since its an amp meter it's just like if it was not there. I don't get how you can use the tension divider law if the the middle of the two vertical branches are connected with a wire (since I consider the amp meter as a wire, "ideal amp meter").


texts:
I just broke my sewing machine (it's an old Viktoria machine about 30-40 years old) and now I am looking for a replacement safety capacitor. The one installed is a RIFA PME 271 M 547 paper capacitor.

I have looked online and found a replacement on ebay
RIFA KONDENSATOR 275V~ SH 47n X2 PME271M 40/100/56/C or this one EVOX RIFA - PME271M547M - CAPACITOR, CLASS X2, 0.047UF.

My problem is, that the old Capacitor has a different number sequence.

It's a bit hard to see but it reads 40/065/56 while all capacitors I found had 40/100/56. I tried to find out the meaning of this values but could not find an answer.

Questions:

Is it ok to buy the capacitors I found?
What do these numbers mean?

Any answer is appreciated


texts: using a capacitor for an off-grid system

texts:
New to the side and have very little knowledge on electrical systems.  I'm trying to come up with a good off-grid system for my small house and have the idea of a PV array with a battery bank, charge controller, and inverter to charge during the day, and then have a bicycle running a car alternator to charge the batteries/help with load during the evening when I workout.

Now my question is, we intend to run some high-draw appliances such as a vitamix blender, food processor, etc. from time to time, and will these appliances need a capacitor to help with the large draw when we first turn them on?  Both to protect other devices running off of the electric system and also for the batteries?  I'm assuming so, but wanted to make sure so I don't spend money unnecessarily.  Also, how would I calculate the size of capacitor I'd need if it is necessary?

Also, correct me if I'm wrong, but I should not be overly concerned with the battery bank being depleted from appliances like this since they are on for a minute or less at a time?  I'm planning on a bank of about 400-800 amp-hours.  Please correct me if I'm mistaken!

Thank you all very much in advance!


texts: The LCD of my MSP430 development board doesn't work when voltage biases are generated externally

texts:
I am programming the LCD of my MSP430FR6989 development board (MSP-EXP430FR6989), and I have a question regarding generating VLCD (V1) and LCD biasing.
The development board got a 14-segment, 6 digit LCD connected to the MSP430 (MSP-EXP40FR6989 User Guide pg 11/41), and the MSP430 got an LCD module (LCD_B and LCD_C module).
In order to turn on a segment, we set the relevant segment line (Sx) and the COM line (COMx), by writing a certain word to the LCDCMEMx registers.
These are the things we need to configure before writing values into the LCDCMEMx registers:

Set th Vlcd (V1) to be sourced from internally from the charge pump or externally.
set the value of Vlcd (V1)
set the bias, 1/2 bias or 1/3 bias.
configure the source of V2 - V4, internally or externally (R23 pin, R13/LCDREF pin, R03 pin)
Source V5 from Vss or from external R03 pin
set the LCD's frequency (flcd)
Add a capacitor to the LCDCAP/R33 pin.
set the correct segments and COMs using the LCDCMEMx registers
Turn on the LCD

I would like to have V1 sourced internally, 1/3 bias, V2 - V4 sourced externally from R23 and R13/LCDREF pins, V5 sourced from R03 pin, flcd = 512Hz, Vlcd (V1) = 3.44V, the MSP-EXP430FR6989 has a capacitor and resistor network attached to it (MSP-EXP430FR6989 User Guide pg 29/41).
As you can see in the code below this is the value written to LCDCVCTL (SFR responsible for the LCD_C module's voltage) LCDCVCTL = 0x1E68 which is 0001 1110 0110 1000
That is the code relevant to the LCD Voltage and bias generation FYI
#include <msp430.h>

//code

#define ENABLE_PINS 0xFFFE

#define TURN_ON_LCD     (LCDCCTL0 |= LCDON)
#define TURN_OFF_LCD    (LCDCCTL0 &= (~LCDON))
#define CLEAR_LCD_MEM   (LCDCMEMCTL |= LCDCLRM)

//code

void init_LCD (void);
void show_Char (unsigned char ch, unsigned int pos);

inside main () function
int main(void)
{
    WDTCTL = WDTPW | WDTHOLD;   // stop watchdog timer
    PM5CTL0 = ENABLE_PINS;

    //code
    init_LCD ();

    show_Char('F',1);
    show_Char('O',2);
    show_Char('R',3);
    show_Char('A',4);
    show_Char('T',5);

    TURN_ON_LCD;

    while(1);

    return 0;
}

Inside the init_LCD ()
void init_LCD (void)
{
     //code

    //configuring: COM0 COM1 COM2 COM3
    //R23 R13/LCDREF R03
    P6SEL1 |= (BIT0 | BIT1 | BIT2 | BIT3 | BIT4 | BIT5 | BIT6);
    P6SEL0 |= (BIT0 | BIT1 | BIT2 | BIT3 | BIT4 | BIT5 | BIT6);

    LCDCCTL0 = (LCDPRE__16 | LCDDIV_3 | LCD4MUX | LCDLP);

    LCDCVCTL = 0x1E68;//external biasing
    //VLCD = 1111, LCDCPEN = 1, VLCDREF = 00, VLCD = 3.44V
    //R03EXT = 1, V5 sourced from R03 pin
    //LCDEXTBIAS = 1, V2 - V4 sourced externally, and internal bias generator is switched off
    //VLCDEXT = 0, VLCD (V1) is sourced internally from the Charge Pump
    //LCDPEN = 1, Charge Pump is enabled
    //LCD2B = 0, 1/3 Bias

    //LCDCVCTL = 0x1E08; //V2 - V4 generated internally

    LCDCCPCTL = LCDCPCLKSYNC;//TI

    CLEAR_LCD_MEM;

}

However, when I build and download the code into the development board, I don't see any segments being turned ON.
I changed the code to configure the LCD's bias to be sourced internally LCDCVCTL = 0x1E08 which is 0001 1110 0000 1000, and the LCD segments got turned ON.
LCDCVCTL = 0x1E08;
//VLCD = 3.44V
//Charge Pump enabled
//V1 generated internally
//V2 - V4

Kindly help me with this issue
Documents I used for reference:

Designing with MSP430 MCUs and Segment LCD Application Note
MSP-EXP430FR6989 User Guide
MSP430FR6989 User Guide
MSP430FR6989 Datasheet


texts: What were to happen if I short-circuited electricity generated by a power plant to the Earth?

texts: I'm not sure how to word this better, so I hope this makes sense. Let's say theoretically that I connected a cable from the hot side of the power lines that run along the road to a stake in the ground, essentially short-circuiting electricity from the power plant to the Earth. What would happen? What would be the risks and hazards of this?


texts:
I am creating a circuit that will light an LED when either signal A or signal B is high. I know of three choices to accomplish this: a diode based OR Gate, a transistor based OR Gate, or an OR gate IC (Schematics below). Aside from minimizing cost and part lists, what are the pros and cons of each?

Edit 1:
Full disclosure. I am recreating the Adafruit Powerboost 500c Circuit, but I want to reduce the LED's I need down to one. It has four LED's to represent the following signals, next to which I put the desired behavior for my circuit:

BLUE - Power (I don't care about this signal)
RED - Low Battery - The LED should be lit when the battery is Low.
ORANGE - Charging - The LED should be lit when the battery is charging.
GREEN - Fully Charged - The LED should be unlit when the battery is charged.

I am removing the BLUE LED and R5. I am removing the GREEN LED and R7. I want to light a single LED if either the input to the RED LED or the input to the ORANGE LED is high. I wasn't sure if just hooking both inputs to an LED without other circuitry was a good idea so I googled "OR Gate circuit" and discovered three possibilities: a Diode OR Gate, a transistor OR Gate, and an OR Gate IC. If any of these is the best choice, which is it and why? If none is best, then what is? I would like to reduce costs if possible.


texts:
I`m currently building a dual slope ADC with discrete components. As expected, some errors were observed. I have calculated both the gain error and offset error variables.
Now that I know these variables, how can I apply the required compensation and is it better to implement it in software or hardware?


texts: converted cordless drill to corded drill - only works once

texts:
I have read several articles about converting cordless drill into corded drill.

I have an old Craftsman 10.8V NiCd battery. It comes with 2 batteries. One is completely dead and the other is 90% dead. I opened the battery, it is basically a bunch of NiCd cells connected in series. No circuits whatsoever. I decided to do away with the cells and convert it to corded.

I found a Switching Power Supply that outputs 12V/12.5Amp. I thought 12V is close enough and proceed to convert. But when I put it together, it didn't work. When I first press the trigger, the drill works great. But as soon as I release the trigger, it stops working. I have to unplug the AC and plug it back in only to repeat the cycle.

I read several similar posts but none reporting the same issue. I figured maybe it is because of the safety feature of the Switching Power Supply but I can't see why it fails only when I stop the drill. It is hard to find a P/S that gives out high current. I wonder if there is an explanation to the behavior and if there is a simple way to fix it?