texts:
I'm a beginner in electronics field . In hybrid and pi and T models we have a resistance called r0 or ro . What's the correct name ? Is it "r-zero" or "r-o  (15th alphabet letter)". Pls give references . Different people say different stuff !

Thanks ...


texts: Copying/imitating wireless garage opener radio signal

texts:
I aim to be able to copy my garage door opener onto another device, but for that to be doable I first have to be able to recreate the radio signal that is sent from the garage opener.

Is there any way to read the signal of a radio transmitter and be able to "store it" for later use? That is, reading the signal and implement it into my own software. So I recreate the signal from my Pi whenever I want to open the garage door.


texts: Power analysis after placement and routing of ASIC

texts: How can I procure the files stating the details of power consumption of the chip after PNR in SOC Cadence Encounter?


texts:
I am trying to generate short pulses as low as 31ns (on time) with a frequency of 10 Hz to 10 kHz.

Microcontroller: Atmel Xmega
Clock: 32 MHz
PWM timer: 16-bit

I am using PWM channels to generate the required pulse. I'm able to get 31ns pulse using compare channel OCnX. But   because of 16-bit timer I couldn't get the required frequency levels in few Hz.

Is there a way to solve these type of problems.


texts:
entity TestRun01 is
    Port ( Clk : in  STD_LOGIC;
           Din : in  STD_LOGIC;
           Dout : out  STD_LOGIC_vector(11 downto 0));
end TestRun01;

architecture Behavioral of TestRun01 is
    signal regr : std_logic_vector(11 downto 0) :="000000000010";
    signal reg  : std_logic;
begin
    process(Clk,reg)
    begin
        if falling_edge(CLK) then
            if Din ='1' then
                reg <='1';
            elsif  Din='0' then
                reg <='0';
            else
                reg <= reg;
            end if;
            regr(0)<=reg;
            regr<=regr(10 downto 0) & '0';
        end if;
    end process;

    Dout<=regr;
end Behavioral;

why only shift '0' to the shift register?

if I change the code from

regr(0)<=reg;
regr<=regr(10 downto 0) & '0';

to

regr<=regr(10 downto 0) & '0';
regr(0)<=reg;

the bench mark shows


texts:
Possible Duplicate:
  Interesting/Unusual/Old Electronics nomenclature

I've been getting into some minor board design work lately, and got confused a few times, because some of my colleagues were talking about "spinning" boards or getting things right on the first "spin" of a board.

Where did the term "spin" come from for fabricating / printing a circuit board?


texts: Schematic to wiring diagram check for 3 mic mixer circuit using TL081

texts:
Need a bit of community validation to see that mapping of the following circuit schematic:

to this hand-drawn wiring diagram seems correct, and there are no obvious mistakes:

Also, does having 2 (or 3 inputs) instead of the 4 shown in schematic impact the circuit characteristics in any way ?

Similarly, does having more than 4 inputs instead, impact this circuit characteristics in any way ?


texts:
I have made circuit that runs on USB. however, when i plugged into front panel of my pc or raspberry pi, it only gets around 3.3v, but when i plugged it into back of my pc, it gets 5v as intended. Shouldn't all USB output same voltage? I have tried both USB 3.0 and 2.0, and on back of my pc, 3.0 outputs 5V and 2.0 outputs 2v. the other ports outputs same 3v whichever 3.0 or 2.0
Edit: Rebooting solved the problem :(


texts: What will happen if I connect a resistor to a constant current LED driver?

texts:
What will happen if I connect a 120 Ohm resistor to the outputs of a constant current LED driver designed to provide 0.600mA (24 - 38 volts)?

According to Ohm's law this resistor will allow a current of ~0.300 mA to pass at 38 volts. Will the driver work fine under these conditions? Or will it try to reach its target (0.600mA), heat up and burn my house?


texts:
So I'm using CADENCE and I'm trying to learn layout.I'm using the AMS 0.35 um technology.
The question asks us to connect vdd (in layer MET2) to the bulk of a PMOS transistor. However I'm not sure if the answer is correct. It says that we should do MET2-VIA1-MET1-CONT-NPLUS-NTUB.
So MET2-VIA1-MET1-CONT seems right to me. MET1 and MET2 are the metal1 and metal2 layers and VIA1 is the layer that connects this 2. Then comes the contact layer CONT.
My problem is with the next step.
First of all I don't understand why not including the active layer DIFF after CONT. Doesn't it need to be included? Then shouldn't we do CONT-DIFF-PPLUS since we want to receive a P implant (it's a PMOS after all). Finally we connect it to the n-well (NTUB).
So we get: MET2-VIA1-MET1-CONT-DIFF-PPLUS-NTUB. Is this correct?


texts: N-MOSFET driver for P-MOSFET high side switch

texts:
I need to create a high side switch to drive a 2.5W resistive load, which must be referenced to ground. I'm planning to use a P-MOSFET as load switch. The problem is there I have an inconstant voltage source from a battery (from 4.2V to 2.5V) and my logic works at 3.3 V. I use a step-up/step-down converter to stabilize voltage at my microcontroller.
I therefore would like to use a N-MOSFET as a driver for the P-MOSFET to ensure that the P-MOSFET will always be closed and open whenever I need. I will drive the N MOSFET woth a PWM signal at 500 Hz.
Will this topology work?

simulate this circuit – Schematic created using CircuitLab


texts:
I have interfaced a HID bar-code scanner with LPC2468. It is sending data when i scan a bar-code, it sends a lot of bytes when i make a scan, how can i know out of these bytes which are the bytes corresponding to the scanned bar-code.

For eg:If i scan a bar-code having value 2M12264185 it send following data

 1: Input Report:
    2: Input Report: 0, 0, 0, 0, 0, 0, 0, 0,
    3: Input Report: 0, 0, 1F, 0, 0, 0, 0, 0,
    4: Input Report: 0, 0, 0, 0, 0, 0, 0, 0,
    5: Input Report: 2, 0, 0, 0, 0, 0, 0, 0,
    6: Input Report: 2, 0, 10, 0, 0, 0, 0, 0,
    7: Input Report: 2, 0, 0, 0, 0, 0, 0, 0,
    8: Input Report: 0, 0, 0, 0, 0, 0, 0, 0,
    9: Input Report: 0, 0, 1E, 0, 0, 0, 0, 0,
    10: Input Report: 0, 0, 0, 0, 0, 0, 0, 0,
    11: Input Report: 0, 0, 1F, 0, 0, 0, 0, 0,
    12: Input Report: 0, 0, 0, 0, 0, 0, 0, 0,
    13: Input Report: 0, 0, 1F, 0, 0, 0, 0, 0,
    14: Input Report: 0, 0, 0, 0, 0, 0, 0, 0,
    15: Input Report: 0, 0, 23, 0, 0, 0, 0, 0,
    16: Input Report: 0, 0, 0, 0, 0, 0, 0, 0,
    17: Input Report: 0, 0, 21, 0, 0, 0, 0, 0,
    18: Input Report: 0, 0, 0, 0, 0, 0, 0, 0,
    19: Input Report: 0, 0, 1E, 0, 0, 0, 0, 0,
    20: Input Report: 0, 0, 0, 0, 0, 0, 0, 0,
    21: Input Report: 0, 0, 25, 0, 0, 0, 0, 0,
    22: Input Report: 0, 0, 0, 0, 0, 0, 0, 0,
    23: Input Report: 0, 0, 22, 0, 0, 0, 0, 0,
    24: Input Report: 0, 0, 0, 0, 0, 0, 0, 0,
    25: Input Report: 0, 0, 28, 0, 0, 0, 0, 0,
    26: Input Report: 0, 0, 0, 0, 0, 0, 0, 0,

How to distinguish data bytes from other bytes.


texts:
I want to sample a voltage signal from mains. I found the following circuit but im not sure how it works. The circuit consists of precision amplifier and a buffer which I can't make sense of, the rest is okay. I've did a simulation using a voltage divider and a reference voltage IC but I also would like to understand this scheme and compare between the results. Please help understand this circuit.

Source:

http://www.ti.com/solution/power_quality_meter#

http://www.ti.com/lit/df/tidrfk9/tidrfk9.pdf


texts:
Load sensor required external module HX711 (ADC converter 24bit for weight) for ADC converter. This module is then connected to the controller.

If I have a controller with inbuilt 24bit ADC, then is it OK to interface load sensor directly with the controller's ADC pin?

Or is it compulsory to connect external ADC converter, or any specific application that HX711 compulsory connect?


texts:
I'm studying the typical circuit implementations of push pull regulator topology.
I have a question about it's off cycle. When the secondary get exited on the off cycle
there is a back EMF also exited on the primary too , since the transformer is symmetric
this is large as the primary current of the ON cycle.And because overall flux in the core is trying to depleted through the easiest path, so then there should be a huge current flown through that reverse diode ? Am I right here?

So the internal diode of the IRF44n would lead to flow massive amount of energy throug
it. Isn't it? And get the device fry, or reduce the overall efficiency of the SMPS module?

Is that mean a circuit like this is a complete flaw?


texts:
I have read somewhere:

"The advantage of using
relative mode over direct mode is that relative addressing is a code which is position-independent, i.e. it can
be loaded anywhere in memory without the need to adjust any addresses."

I can't understand this part. why we need to adjust addresses in direct mode but not in the relative mode.

and please give a brief explanation of this part:

"Also, relative addressing is
particularly useful in connection with jumps, because typical jumps are to
nearby instructions."


texts: Difference between DC-DC Switching "Controllers" and "Regulators" and "Converters" please?

texts:
I'm looking for a switching regulator for my design, and I head over to Digikey... Now I'm curious what the general difference is between these categories:

PMIC - Voltage Regulators - DC DC Switching Controllers
PMIC - Voltage Regulators - DC DC Switching Regulators

They both seem to contain very similar devices and I'm just not seeing the distinction.


texts: Why does voltage go in one direction and not both?

texts:
Hello I have this inverter circuit I made that is connected to a button when the button is on one led is on and the other is off and vice-versa.

simulate this circuit – Schematic created using CircuitLab

What should happen is that when the button is pressed voltage flow to one led AND to the transistor base, but it only goes to the transistor base. What am I doing wrong?

Thanks for the help everyone but I found a solution ill post it for people with the same problem in the future. I used a resistor calculator I found on the web and changed R3 to 150 ohms, removed R5 and added a 330 ohm resistor before D1. Thanks for the help anyway!


texts: Measuring conductance of the material used in fabricating Antenna

texts:
I have a composite polymer material with injected conductive particles inside it, making it a not-so-perfect conductor. I have also fabricated a simple dipole antenna using the wires made of the composite, and it is radiating at 2.4GHz without any problems. Checked with a network analyzer.

I have also tried to simulate it using CST microwave simulation software, but since the material is "home-made" and not defined in software material library, I have to define it by myself by specifying the conductance of the material and define it as a "Lossy metal".

For this, I tried to measure the DC resistance of the material and calculated conductance from it, which shows relatively high resistance and therefore low conductance. I also tried to simulate it with the values that I got from the measurement but there was no luck and it acted like a normal dielectric without any radiation.

The material looks resisting in DC but conducting as a 2.4GHz dipole antenna?

Am I doing something wrong? or forgot something? And what should I do to simulate accurately?


texts:
A MSP430F1232 is connected to a PL2303, i.e. URXD0/UTXD0 are connected to the PL2303 TX and RX. VCC and VSS also come from the PL2303 (over USB). In addition, a switch with a pull-up resistor and a LED with a resistor to ground are connected to P1.0 and P1.1.

The circuit and program are working as expected. However, the circuit is also working when VCC is not connected. The reason is a voltage of about 3.2V on the UART TX. When I also disconnect the TX connection, the MSP430 stops. Nevertheless, when the TX is connected, the MSP430 still works as intended and the serial interface also works.

How would one implement a switch to completely turn off the circuit / MSP430? My idea of using a switch between the PL2303 supply and the VCC pin is not sufficient.


texts: How do I make use of a scrapped CCD sensor from a scanner?

texts:
I obtained an old scanner with no power adapter. I wired it up to something with a compatible adapter, but apparently this particular scanner is very tied to it's power supply(even though it's suppose to be regular 12V DC). There were numerous reports online of it not working until they used an official power supply. I couldn't get the scanner to work at all in Windows and it'd display nothing but noise in Linux.

So, I stripped it apart. Inside, I found what is apparently a CCD sensor for the scanning functionality. This sensor has no kind of part number on it in any way. I looked at Wikipedia for some info about CCDs, and online. But, I never found any real documentation about how to make use of them. I'm imagining a very crude camera project. How could I get an image out of this thing with either an Arduino or FPGA?

Pictures: (click to enlarge)

Also, in the last picture, the 4 SMD chips are 74ACT04 hex inverters


texts: Why High Speed CAN messages with a recessive level in ACK slot from OBD II port on 2019 GM Chevy Cruze

texts:
I want to collect some CAN traffic from my car. I got two devices. One is Saleae Logic8. The other is Vector VN1630A. I think the CAN protocol is straightforward that we can listen the CAN traffic by connecting our device to CANH and CANL. So I connect the Saleae Logic8 to the pin 6 and 14 of OBD II port, which is HS-CANH and HS-CANL respectively. However, I got a CAN traffic which is repeatedly messages with a recessive level in ACK slot, as shown in the pics. The voltage showed in the pics is differential voltages by CANH minus CANL.

Let me clarify what the pic showed. The identifier showed which is '456' is decimal number, and its binary is '001 1100 1000', which is correct for the transmitted message. The red cross in the pic means the stuffed bit. Sorry for the confusion.

The same messages is repeatedly sent and seems like there is only one ECU on the bus. However, if I connect the professional CAN bus tool, Vector VN1630A, I can get the normal CAN traffic, many different messages. I then connect the Saleae device to my 2009 Mazda6 OBD pin 6 and 14, it also can detect normal CAN traffic.

Is there any difference in newer vehicles' OBD port? Or is there any request command I should sent firstly to get a stable, normal CAN traffic?
Thanks for your help!


texts: How to use LEM LAH 50-P current transducer

texts:
I have a school project that implements a digital electronics power converter. It will be a current controller. The power source is also voltage controlled using a commercial power converter. The voltage controller switches at about 20 KHz. The current drawn from the power source must be sampled.

Is the LEM LAH 50-P current transducer able to satisfy the requirements? It has a step response time of under 500 ns (2MHz). If the voltage controller is switching at 20 KHz, can the current be sampled at 40 KHz?

Is the following the correct mode of operation? :

Place the sensor in series with the power line (breaking the line by connecting one end to the in terminals and the other to the out terminals). Then connecting 12 to 15 V to the Uc terminals.

I would be mostly guessing after that. Can someone explain?


texts: HCMOS Oscillator pull up / down resistors

texts:
I am new in this forum, I will listen and thank all your support. My goal is to know how to design the oscillator output resistors to enhance / optimize clock signal performance.

I have been working with the ic oscillator QX333A10.00000B15M and a FPGA Microsemi A3P1000. The datasheet of the oscillator does not specify any recommended circuit, however I have found two interesting documents:

https://www.microsemi.com/document-portal/doc_view/130778-proasic3-e-starter-kit-user-s-guide

https://irp-cdn.multiscreensite.com/0c45c4a0/files/uploaded/Oscillator-Application-Notes.pdf

In the first document, page 33, there is a circuit that models the oscillator, with a voltage divider and a serial output resistor. In the second document, page 4-5, there is some explanation about how these resistors are used to avoid signal reflections, however I does not understand at all, as well as what values select for the resistors.

Thank you very much for your help,
Antonio Moreno.


texts: Frequency Hopping 900MHz -- Noise Floor Mitigation and Algorithim Design

texts:
I've built a few baremetal fixed frequency RF systems, and am working on a long range frequency hopping product using a ARM Cortex M3.  So we got some horsepower here!

I've got the the TX FCC Part 15.247 compliant hopping across 60 channels and using an extremely narrowband signal to hit our range requirements. Average message time is 190ms (~50ms pre-amble, 140ms sync word + packet).

Product market is USA, so everything is being done to be FCC compliant.

It's an odd system because the goal is to simply deliver one single packet and take advantage of the increased transmit limit.

If the system were more bursty, I would just start on Hopping Channel 1, and go through all 60.  But we have a very tight latency requirement.

We need the system to respond within 300ms of a transmit.  If we loop through all 60 channels, that takes nearly 10 seconds. If we change the bit rate, we won't hit our distance.

I've got the RX cycling ~800us per channel to an asynchronous scan of all 60 channel, taking an RSSI read, and than dwelling on the strongest channel.

On my desktop, I'm getting about 80% of the packets through.

I did some more digging, and it seems like I am getting a lot of ambient noise in the 900MHz range that trips up my detector.

I added an RSSI limit, and that improved the system to about 90% of the packets.

But this is simply on my desktop!  From my experience I know this system isn't going to go far, this narrowband signal blends into the noise floor quickly but somehow the receiver is so sensitive it goes quite far (800 meters +).

I have thought about averaging the noise floor which might help (take your pick simple moving average or something more microcontroller friendly [I'm more of an 8 bit guy, so I have to see if the M3 really needs an MCU friendly scheme).

System mechanical really are one unit is TX, and one is the RX.  So I haven't really digested a re-transmission scheme yet.  The latency timing probably wouldn't work from a user perspective either.

Has anyone tackled a frequency hopping scheme like this?  Any ideas how to mitigate the amount of 900MHz noise out there but still get our signal through?


texts:
I just came from the local library, it’s quite big, and most of it is made of an architectural design using mostly painted metal book shelves painted with some kind of anticorrosive paint along with glass floor all over the place, everything was fine and nice, until I started to get static electricity shocks around every single book shelf (yes the painted ones) in every floor almost all the time I took around 13 shocks in less than 20 min

As you can see most of the metal structure it’s joined by huge bolts (screws) so there is continuity all over the place (I checked) also there is a possibility to the metal structure to be joined to the structural studs of the building

I’m trying to find out how is it possible to "fix" something of this magnitude
As an antecedent I installed an antistatic mat in my own home lab, along with the nonexistent at the time grounding rod and wiring across all the home, I do know antistatic mats have a huge impedance that “slows” the flow of current to mains earth while it discharges the body slowly to protect electronics of voltage differences between the desk, user and electronics, being at the same potential, like in the following picture

My theory for the library is that the users being insulated of earth and by being walking around a glass floor, are generating  static electricity just by walking with their clothes on, the electrons find no way to discharge around the glass and as soon as they  touch any metal book shelve they get discharged, there’s a chance of the system being grounded to mains earth, but as I recall a door knob can shock you like this even by not being grounded so I’m not sure, and a bit confused now

I’m thinking on several ways to solve this

1)  The first idea that came to my mind was to to an arragement like an antistatic mat, add a 10MOhms power resistor to join the book shelves in several points to mains earth, this “might” slow the current flow of electrons and no shocks will be sensed, however my common sense tells me that the mat itsle fhas a high impedance unlike the book shelve, this might work to slow the flow across the resistor but it would make nothing for the user that will still get shocked due to the low resistance of the metal book shelves  and THEN it will be slowed down across the resistor

2)  Second I thought of painting the shelves but then I noticed they were already painted and the shock were happening even above the painting

3)  I thought about looking for the bounding point to mains earth and, leave the metal structure as a “floating circuit” with no connection to mains earth, but this might get complicated since as i said before the metal structure might be touching the internal building structure

And from all this possible solutions,  several questions arise,

a)   Can static shocks occur from grounded and ungrounded metals?
b)  How do you prevent getting zapped when everything around you is
metal and glass floors?
c)  What is the worst case scenario if I unbound the metal structure
from mains earth? (Not contacts, nor lighting rods, just make sure to
leave the metal book shelves ungrounded), will the user still get
shocked?


texts:
I have looked for a solution to my problem, but none of the answers I have found quite help me.

I am a beginner at electronics but have a general understanding of the physics behind electrical systems and circuits. I have a water pump that is powered from a 120VAC wall outlet, which will be used to move water in a makeshift fountain I am assembling. I want to power some 6VDC LEDs from the same plug to give it some lighting effects but I dont want to accidentally cut off the power to the small water pump. I have seen various posts about getting a transformer or capacitors to drive the LEDs but I cant quite get my head around how to implement any of these solutions. I know I can use batteries to drive the LEDs but if I have to plug the pump in anyway, I would prefer to power the entire fountain and LEDs from one plug.

Thanks in advance.


texts: DC motor as a generator as well as a motor in a car

texts: Not sure if this was asked before, but can I use a DC motor to power the front axle, but then use the same DC motor as a generator when the vehicle is braking. Can I have a link which helps choosing which DC motors is best as a generator


texts: How to make Eagle package with dual row surface mount tails?

texts:
I'm doing a project using the OMNETICS dual-row connectors (http://www.omnetics.com/neuro/pdffiles/A79025-001.pdf). I'm a bit lost about how to make the package for it in Eagle, as the connector has horizontal surface mount rails that's supposed to solder on both the top AND bottom of the board (straighten the solder pins so the two rows straddle a board).

Any help (or perhaps library for this part) is appreciated.


texts: Calculate the turn-off delay of an LED in parallel with a capacitor

texts:
I am trying to create a Custom turn off delay for an LED. For this I take an Capacitor in parallel to an LED

My Idea so far was:

I have the General Equation for an Capacitor. And the General Equation for Discharge. My U0=5V. The current is "controlled" by the LED. For the LED I assumed the Equation for an Diode Current. Now is the part where I assume, I did something Wrong. Because the Current Equation depends on the Voltage I inserted the Discharge Equation. Now I Put everything in the General Capacitor Equation. Because even WolframAlpha couldn't solve this Integral I assume I messed it up earlier. Can anyone help me?For this example -> I assume an Vf von 2V

//EDIT: Added Equation in Latex


texts: I need help deriving the cutoff frequency of a negative feedback amplifier

texts:
I have the question and answer below for deriving the closed-loop cutoff frequency of a feedback amplifier circuit. I can follow the working out all the way until the last 2 lines, where the writer rearranges \$A(f)\$ and then forms the cutoff equation, \$f_{cc}\$.
I think they've missed out a couple of steps in between, so could anyone explain how to get to those last couple of lines?

Going from \$A(f)=\frac{A_o}{1+j(\frac{f}{f_c})+A_o\beta}\$ to \$A(f)=\frac{A_o}{(1+\beta A_o)(1+j\frac{f}{(1+\beta A_o)f_c})}\$
Going from \$A(f)=\frac{A_o}{(1+\beta A_o)(1+j\frac{f}{(1+\beta A_o)f_c})}\$ to \$f_{cc}=(1+\beta A_o)f_c\$


texts: Custom Arduino powered board (CH340C) Serial Problem

texts:
I made this custom board that contains a complete arduino nano on it. I soldered every component with extreme care and already check all the connections and they all go according to the designed schematics. But i seem to have a problem with the serial communication between the computer and the board. Im almost certain the problem has to do with my CH340C IC, but i have already replaced it 3 times.

This is the problem:

I know the arduino is working because i burned the bootloader and uploaded some example sketches to it trough the ICSP pins.

So maybe i have a design flaw? If I do please let me know.


texts: Heating up water with electrical current

texts:
Is it possible that (isolated) wires carrying high current, such as 200A, passing through water will heat up that water like a boiler?

I have been told by someone that a fuse panel in a building had its bottom immersed in water and apparently this created a lot of heat and steam. Does this make any sense?

I know that inductive heating COULD possibly occur, but we are speaking 50Hz and no coils but straight wires. Usually one would expect that with frequencies in the kHz range. Resistor-type heating would probably not have occured either since wires in a fuse panel would be highly conductive.


texts:
I think this question is best asked on concrete-ish terms, so, here it goes.
Let's say we have 4 wires, all with common ground:
A) ≈9V-20V, varying.
B) ≈3V-6V, varying.
C) A low frequency analog signal (<1kHz), which can vary from 0 to A.
D) In here, I need to output the analog signal from wire C, but translated from range 0-A to range 0-B.
Point of the circuit being that it should self adjust to always translate the signal from range 0-A to range 0-B, even if A, B or both change.
I'm basically stuck, any pointer or a suggestion would be appreciated.


texts:
I want to be able to turn TFT screen on and off using MCU. Is it safe to put a FET on the ground line of TFT and drive it from MCU, by disconnecting and connecting ground from the screen? or should I use p-type feet on power line to switch it? I am not sure if it's a good idea to leave TFT internal electronic's floating.

EDIT: LCD TFT 2,4"240x320 Arduino shield, MCU is barebone Arduino(Atmega328P) and FET i planned to use is 2N7000.


texts: Can boost converter operate under these conditions?

texts:
I am wondering whether the boost converter is possible to operate with these conditions below or not:

All components or sources are ideal
Initial voltage across output capacitor is zero voltage.

Another question, if the voltage source and all components are ideal, then the driving current at the output can be infinite. Is that right?


texts:
Hey guys I'm currently designing a schematic for a super capacitor spot welder and I'm working on the control system for the MOSFETs.

I'm planning on using a gate driver instead of just resistors and zeners because of the very high burst current (couple hundred amps for 10 to a couple hundred milliseconds) and the heat the transition time would create.

Pretty much just having some trouble deciding what driver IC to use. I was using THIS filter to find some ICs and it helped, but there's still a lot of choices.

THIS was one of the first choices on there and it seemed like a good choice, but like I said idk.

I'm planning on just putting 4 MOSFETs in parallel and driving all their gates with the single channel of that IC.

Anyways if anyone has any advice on which IC to use that would be great.


texts: How to find mean length per turn (MLT) for magnetic design from ferrite cores datasheet?

texts:
Mean length per turn (MLT) is an important design parameter in Kg method of inductor design as described in the book "Fundamentals of Power Electronics" by Dr. Robert Erickson.

Where is the MLT mentioned in this datasheet for EE cores on page 21?

How is the formula derived in the screenshot from the book by T.Mclyman?

By Robert Erickson

By Mclyman


texts:
I've recently been searching for a simple, easy yet cheap way to reflow SMDs on a PCB board as I have never tried it before and always wanted to create a small and compact circuit. I then found a crowd funding campaign (whom I will not currently name because my point isn't to advertise) of a product where instead of a soldering oven, it was a hot plate. However in general, hot plates aren't the best for reflowing as the heating is uneven unlike this one where it claims to have an even heating surface (also because it's quite small).

If such product exists being a hot plate that evenly heats up the PCB, how would that be anyway advantageous over a soldering oven? One way I can think of is being able to re-shift the components if they move during the reflow. Any problems or disadvantages?

In addition, Is it safe to put components at 219 degrees Celsius when their max storage temperature is 150 degrees celsius? Looking at the reflow process, for 75 seconds, the oven or the PCB reach over the max (and the hot plate crowd funding product follows this exact same profile). And when looking for a PCB, what aspects should I be looking for to ensure it is reflow friendly? I'm guessing most PCBs are designed for this.


texts: I am searching for some current measuring ICs and found the ACS712, but what I can't figure out is how the seemingly small pins can handle the 20 A current since the trace width calculators say that I need a trace that is almost an inch thick to handle the same current.


texts:
I'm trying to write a linker script for my first firmware for STM32F103C8T6 microcontroller. I have an example script that works. What I'm trying to understand is why it works.

The linker script I have defines two memory locations:

MEMORY
{
    FLASH (rx) : ORIGIN = 0x08000000, LENGTH = 64K
    RAM (rwx)  : ORIGIN = 0x20000000, LENGTH = 32K
}

Official STM32 programming manual section 2.2 states that "Code" memory section starts with address 0x00000000. The next section is RAM, which is 0x20000000, just like stated in my linker script.

Where the FLASH origin value 0x08000000 comes from?


texts: In the following figure, we want to find V Thevenin. I tried combining the two 3v sources (3+3=6v due to their polarities) and applied voltage divider to find the voltage across the 150kOhm resistor which is Voc or Vthevenin, but it turned out to be 3.73 which is different than the professor's Voc. Is it because of the ground between the two voltage sources that doesn't allow us to unite them?


texts: Is there any simulation environment provided with TDC-GP1 counter frimwaire?

texts: hello everybody I want to simulate an electronic circuit, I used TDC-GP1 (Time to Digital Converter) I searched in Proteus and in Pspice Cadness but didn't find this part in library, is there any simulation environment provided with TDC-GP1 counter?


texts: Please check my board design before I waste money

texts:
TL;DR: Please make sure my schematic and board design won't blow up on me. GitHub Repo if you're feeling extra thorough.
Project overview
I am trying to create an Arduino based Bluetooth RGB led controller, but larger-scale than most. I'm planning on having 25 meters of (common-anode) 12v led strips, which means about 300 watts of lights. I'm using a scavenged Corsair CX430M for power, and as a housing for the Arduino.

I've already programmed the ESP32 brain and set up the circuit using a single RGB led with transistors instead of MOSFETs, and resistors between the emitter and ground. I don't know how closely that performance will translate to my PCB setup.
Main Schematic concerns
1: I've read that the 2 resistors before the MOSFETs will reduce accidental switching from trace capacitance or something. Regardless, If something is overkill or dangerously underkill, please let me know.
2: I've selected NCE3080KA MOSFETs. I think I can use just about any MOSFET, but if this one is wrong for some reason please let me know. Right now the PWM is set for a 5kHz, but I'm pretty sure I go much lower. GPIO voltage is 3.3.

sorry for the bad screenshot. I'm not sure what layers should be visible. The full board design is available here
Main PCB concerns
1: The PCB will be passing up to maybe 30 amps of current. To mitigate the issue, I added a stupid amount of vias to help sink heat and left the entire bottom solder mask-free, but I'm not sure if that's sufficient.
2: Manufacturability. Is something wrong with my design that just won't work, or can't be made for some reason?
**Edit 1: ** @WesleyLee pointed out that I switched the mosfet drain and source. Updated pictures to reflect changes.


texts: Does the arduino (ATMEGA328P) ADC really only sample periodically?

texts:
I have been experimenting with the Arduino's ADC, and I have noticed some bizarre behaviour.  I am wondering if it is normal, or if this is something specific (and bad) about the Atmel ATMEGA328P that the Uno is based around.
Basically, it would appear that the input value on the ADC is sampled at a lower rate than the ADC is actually returning values for:

In this image you can see the sampled input running at full speed connected to a simple pot.  As the pot is swept from full to minimum the input voltage drops.  As you can see the returned values from the ADC come in steps, where it returns the same (or similar) value for multiple calls to analogRead(), before then dropping down sharply.
What is actually going on here?  Is the ADC input running at a different speed to the data output?  Is the Arduino code reading the ADC wrong?
I have tried playing with the ADC pre-scaler, and no matter what I set it to (apart from 1:2 or 1:4, where it dies completely) it reads in steps like this.
Edit
It takes about 32 successive ADC reads for the steps to completely disappear.


texts: Relation between SPI, clock rate and data bits in microcontroller

texts:
I am working on a project which requires a UHF RFID Reader IC AS3993 having an 8 bit Reader MCU. And an externally connected LaunchPad (SimpleLink LAUNCHXL CC3200) for data transfer which works at 16 bit/32 bit.

But, the reader IC and external LaunchPad have different clock rates and different bit rates. Then I would like to know how can I ensure proper data transfer using SPI (Serial Peripheral Interface) between Launchpad and AS3993, despite having different clock rates and different bit rates.

Reference links:

LaunchPad CC3200 LAunchXL technical and related documents
AS3993 Block Diagram
AS3993 datasheet


texts:
I want to send a signal through the DC power lines used in railway compartments.

Can you please help me to do that, or provide some documents or links?


texts:
I'm taking an EE course where we have been studying transmission lines, among other things. I know that when I am driving an unmatched load, there will be a reflected wave.

My question is where exactly does this wave travel? Is it along the top or the bottom conductor? On the one hand, I thought current returns on the bottom conductor. Does this mean that the insulator on a coax cable, for instance, is the only thing protecting me from the AC voltage?
On the other hand, if both waves travel on the top conductor, how isn't there interference? Or is that what causes there to be a standing wave?


texts: Why the output voltage of this IC cannot reach higher?

texts:
I'm trying to design a remote control. But during the process of design, I found that the output voltage of IC TPS40057 of the switch can just reach to less than 6V. The simplified application diagram of this IC is in the following：
I don't know why it can't reach higher value. Can anybody answer me why?

For further reference, the datasheet is at http://www.ti.com/lit/ds/symlink/tps40057.pdf.

Any answer will be highly appreciated!


texts: Why are inverter modules extremely oversized in VFDs?

texts:
I was checking a faulty Schneider VFD (ATV312H037N4) which is rated for a nominal output current of 1.5 A. Turns out the rectifier bridge of the inverter module (FP10R12YT3) blew up and after reading the datasheet I was surprised to find out that the IGBTs are rated for a nominal current of 10 A and the rectifier diodes are rated for 1600 V and 25 A. After checking some other drives from different brands I noticed the same thing.

I get that oversizing of components is normal for this kind of application but this seems a little extreme. Why would they do this? What's keeping this VFD from running a much larger motor that's closer to the ratings of the inverter module?

All the heavy lifting is done by the module so I don't see the reason to why the VFD is rated so low.


texts: Why do some power transistors emit light?

texts:
I am specifically looking for an image I believe I have seen before so I can link it to a friend. It was a TO-3 packaged device with the metal cap removed, showing a power device emitting light as a side effect.

I seem to remember it being a BJT, maybe even one of the common variety (2n3055). Have any of you heard of this phenomenon? Can you explain why it occurs? If you can link to an image of this, I would be very grateful.

EDIT

This is one of the links I was looking for
https://lab.whitequark.org/notes/2014-06-14/transistor-as-a-light-source/


texts: Transform a sinusoidal wave into a square wave with op-amp

texts:
Ok guys, I can't understand a thing, how can I turn a sinusoidal wave into a square wave with an op-amp, for example watch this image:

If you pay attention, you can see in the bottom of the image a square signal that correspond to the sinusoidal signal,the square signal is 1 when the sin of the sine curve is growing up, and it 0 when the sin of the sinusoidal wave is decreasing, but how is possible do a thing like that with an op-amp?
For example a circuit that can do a thing like that is the comparator, that compare the voltage, Value of an instant[0] with the voltage value of the following instant, and if the current value is higher than the previous quantised value.
But for example let say that I have an op-amp, in the + gate, i put the signal, and in the - gate, I put the feedback of the op-amp, so for example if in the + gate I have 1v in the output of the op-amp i  find the Vcc, but if I put the Vcc of the - gate(With the feedback) I have on it -5V, and the op-amp will stop working.So how can I do a stuff like that with an op-amp?


texts:
Is there a ratio between the voltage and charge of a battery?

I mean, the voltage falls slowly while the charge is consumed? Or occurs a sudden drop of voltage when the charge is at the end?


texts: Microcontrollers with extreme high temperature range

texts:
I am looking for components which works at high temperature. Especially I am looking for microcontrollers which works at 180 °C to 200 °C.  I need to found microcontroller which works fine at extreme conditions. If the microcontroller have built in CAN interface then it would be really nice? or any other methods and microcontrollers that i can use for my project. The purpose microcontrollers is to get information from different sensors and perform some calibration.

I found one microcontroller from TEXAS which is SM320F28335-HT but the cost of that microcontroller is very expensive. Is there any microcontroller with low cost and works at high temperature.


texts: How can I convert 110V AC to 20V DC that pulls around 1.5 Amps without a transformer

texts: I have a DC fan motor that is currently being powered by voltage dropper in the form of a heating coil, and then bridge rectified. I want to separate the heating coil from the fan motor, but I'm not sure how to go about doing it. I know a transformer is one option, I'm looking for a smaller and less expensive solution.


texts: Maximum safe clock frequency of full adder circuit

texts: A full adder consists of 2 xor gates, 2 and and 1 or gate. The propagational delay of any of these logic gates is 8 ms. I have to find out the maximum safe clock frequency. As there are total 5 logic gates and 8 × 5 = 40 ms. f = 1 / t = 1 / 40 ms. Is it going to be the correct answer? Or am i making a mistake?


texts: How do we interpret frequency from fft command in matlab? When I apply fft to a sampled function(@ Fs) and I get peaks at some values in the fft array. How do I know what frequency in Hertz does it correspond to?


texts:
My project involves hooking up relays to individual plug points so I can control them with a microcontroller. Unfortunately, I am not sure how to approach splitting my mains 240V into 4 different inputs. All I can think now is to use a metal plate, solder the mains to the metal plate, and solder to the live connection of the 4 inputs to that plate. Then do the same for neutral and ground.

Is there a better approach?

(EDIT)

PS I have two possible methods. Can I know which is safer. (Drawn here at this link)

One way option 1 is to solder the main mains wire to a metal strip. Then solder the live wires of my extensions onto the strip. The relay will divide this wire to the extension (I am using an arduino all in one relay module http://dx.com/p/arduino-5v-relay-module-blue-black-121354).

Option 2 is just to use those mains wire caps to join up all the wires. I feel this is safer as I do not have to expose a metal strip inside my project box.

Ideas?


texts: A question about resonance and crystal radio?

texts:
This is a circuit of crystal radio transmitter. I've tested it, and it works properly. but I can't understand everything in this circuit...

L1 and C5 make resonance frequency, Would you tell me if they are series or parallel and why ?

C1 , R1 and C2 for filtering the Audio (input). Am I right ?

What is the function of C4 ?


texts: FPGA + SRAM - floating inputs of SRAM during configuration of FPGA

texts:
I'm connecting SRAM to FPGA (Spartan 6). During configuration and during periods when FPGA will be down (for example I would like to turn off FPGA when external flash will be programmed by uC) address lines of SRAM will not be driven, thus floating - which is bad I guess.

I came up with the idea to use a transistor to turn on / off SRAM. As I have uC on the board, I can connect base of transistor (ex. BC817) to uC and its collector to Vcc and emitter to VCCs of SRAM so I would be able to turn off SRAM when FPGA is down and when it is configured and runnign I can turn on transistor and thus SRAM.

Do you think it will be ok? Is it good idea?


texts:
I have solved  the above problem in two ways.And both the times I have a unique solution with the same number of gates.

According to my understanding of Essential Prime Implicants, This particular case does not contain any essential prime implicants, as two ways of solution is possible.Is my interpretation correct?

But is it possible to have a solution without EPI's?
Help is greatly appreciated.


texts:
As I understand it FPGAs are flexible "digital" circuits, that let you design and build and rebuild a digital circuit.

It might sound naive or silly but I was wondering if there are FPGAs or other "flexible" technologies that also make analog components available to the designer, like amplifiers, or A/D or D/A or transceivers or even more simple components?


texts: STM32F2: Makefile, linker script and start-up file combination without commercial IDE

texts:
I have been working with an STM32F2 (specifically, the STM32F217IGH6 on a development board) for about two months. By far my biggest problem had to do with the "setup", which includes makefile, linker script and start-up file.

In particular, I have been unable to properly set up my interrupt vector table and have interrupt handlers called. ST does provide examples tailored to commercial IDEs. Instead, I am using the free Yagarto recompilation of the GCC toolchain (and OpenOCD to load the image via JTAG).

Are there example projects for my board (or a close cousin of it) which contain the appropriate makefile, linker script and start-up file combination for non-commercial IDEs that are set up for interrupt handlers to be called?


texts: How are statements with uninitialized signals executed on very first EVENT?

texts:
In VHDL Dataflow modeling, all the statements are concurrent for each event.

For example, the event where B is first triggered leads to concurrent executions of statements 1, 3, and 6. But in statement 6 we don't have value for ABAR.

So, will execution proceed with an initial (default) value of ABAR (default to the leftmost value ('left) of its declared type), or what?

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;

entity DECODER2x4 is
port (A, B, ENABLE: in BIT;
     Z: out BIT_VECTOR(0 to 3));
end DECODER2x4;

architecture dec_dataflgw of DECODER2x4 is
signal ABAR, BBAR: BIT;
begin
Z(3) <= not (A and B and ENABLE); --  statement 1
Z(0) <= not (ABAR and BBAR and ENABLE); --  statement 2
BBAR <= not B; --  statement 3
Z(2) <= not (A and BBAR and ENABLE); --  statement 4
ABAR <= not A; --  statement 5
Z(1 ) <= not (ABAR and B and ENABLE); --  statement 6
end dec_dataflgw;

edit:
I have updated the code, have checked it, this one works.


texts:
I wanted to convert volts into dB SPL. Thankfully, I found this article

convert Volts into dB SPL

While trying to understand why he was adding the mic sensitivity along with 94 dB SPL, I found another article

Volts into dB SPL explained

In the first article, during the dB SPL calculation the reference Voltage used is the microphone reference voltage, 0.005012 V RMS (microphone sensitivity of -46dBV/Pa , this gives 0.005012 V RMS) , which I thought is correct and made sense.

However in the second article, he uses a relative voltage of 1V during the dB calculation. He should have used 0.0063096V (microphone sensitivity is -44 db which translates to 0.0063096 V/Pa.)

I still think the first article is right. Can someone clarify if which article is correct or if I've misunderstood something ? Thank you.


texts: Record and recognise IR Code independently from Protocol

texts:
I'm trying to build a device that is able to learn the code sent from an IR Remote when a button is pushed and that is able to subsequently recognize it when received. I need my device to be compatible with all TV Remotes, so that is able to save and recognize a code independently from the protocol used by the remote.

In my opinion, since I need to recognize only one sequence, the better choice is to analyse the raw signal without decoding it the protocol. In this way I don't need to program the uC to recognize different types of protocols and it will works with every remotes, and those that use uncommon protocols.

  My idea is this:

  When the device need to be "programmed" it starts to sample to IR
  Receiver output signal every X time until the signal return to idle.
  These samples are saved in the uC memory.

  When the device is normally working, if an event occurs (the receiver
  output goes low or high), the uC starts to sample the received signal
  and compare it to the reference signal, previously saved.

It this method good or is there a better way to do this?

If this is the better choice, what could be a good sample frequency (considering the difference between the protocols and that they works at different frequencies like 36 kHz and 38 kHz)?


texts: Pick transistor to drive a coil from Attiny85 with 2.5 (+/-500) kHz signal (with screenshots)

texts:
I have a small issue here.

I am trying to drive a coil from an AtTiny85. I am sending an output signal to a transistor and the transistor will then connect to a coil.

I know that I am sending the proper signal to the transistor, but this is not passing it properly to the coil. I am getting an output with noise and it is definitely not a square wave.

Am I missing a Diode? Did I pick a wrong transistor ? Do I have a wrong resistor value?

I am attaching the pictures of the circuit,data sheet and of the oscilloscope.

The transistor picked is an MMBT3904

The signal that is connected to the base is the 2.5 kHz signal coming from the ATtiny that passes trough the 1k resistor.

These are the properties of the transistor.

Do any of you have any ideas or suggestions?

I am adding the pictures of the oscilloscope

The code intends to change the frequency, and it is actually doing it, but not as intended.

I have also changed the BJT for a Mosfet, it did not work. I keep getting the same results.


texts: How can I know that 2 x-bee are paired before or not?

texts: I got 2 x-bee from my school lab, and I want to use it. These 2 x-bee are paired before or not, how can I check it? What should I do to know whether it is paired or not?


texts: Powering two red LEDs via USB port or USB battery pack

texts:
I want to power two red LEDs from a USB charger or USB battery pack.
I want both LEDs to light up at the same time from the same USB cable. Can anyone advise what resistor/s I need to fit in the chain and where, please?

Below are the two different types of LEDs I have available to use:

Red LED Ammo Through Hole, Broadcom HLMP-EG1T-Z20DD
Datasheet & sales page

2.4 V Red LED 5mm Through Hole, Broadcom HLMP-EG1G-Y10DD
Datasheet & sales page


texts: I think I am looking for a specific DC relay switch

texts:
I am looking for a switch not sure what kind though.

let me explain:

I have two sources one creating DC 12v, second one creating around 6v DC.

One source works for about 12 hours each day then stops
the other works about 12 hours each day then stops. The next day this is all repeated.

During each 24 hour day one of these DCv sources is running a load.

What I am looking for is a switch that will automatically open the circuit "cut the circuit" of the DC 12v source that is NOT supplying power at that time, and keep the circuit closed for the one that is supplying power to the load. Then in about 12 hours later when the other DC 12v is ready it automatically opens the circuit of the DC 12v source that is NOT supplying power and so on.

First Source "this source will fluctuate from 12V to 6V
Right now I am getting the below amps at around 5 and a half V
310.2 ma
0.012 amps

Second Source "this source is my backup when the first one looses power" This source "the second source" always has a steady 12V
01.41 ma
0.141 amps

Hope this makes sense.

In summary, when one DC 12v is running the load I want the other ones circuit cut and vise versa.


texts: How do I choose a motor to operate a rotary switching device?

texts:
I need to build a device that has a motor which operates a hefty rotary disconnect switch. The switch is spring loaded in the On and Off positions and I know the operating torque requirement of the switch. The switch has an Aux contact so I can read the position of the switch at any time. I also want to be able to operate the switch manually when the motor is turned off. The motor only has to turn 90 degress back and forth to turn the switch On or Off. I intend to use a Geneva Mechanism between the motor and the switch. I don't know what type of motor is most suited for this project.
Thank you for the comments. What I'm really asking is do I choose a stepper motor, a servo motor, a DC motor (brushless or not?), gearmotor? I haven't worked with motors much - I do mostly embedded PIC stuff - so I'm just trying to pick a path to go down for this design.


texts:
I want to ask you about the following figure, how can I design the values of the LC filter? I mean is there any procedure I can follow to design these values?
thank you in advance


texts: Replacing a custom serial port connector with a Micro-USB 2 plug

texts:
I currently have a very fragile solution to connect my embedded device to a PC's serial port.  This is mounted on the PCB: http://www.digikey.com/product-detail/en/DF13A-6P-1.25H(50)/H3384-ND/530681.  Its companion must be painstakingly attached to the wires of an existing serial cable, and placing any sort of strain-relieving product takes too much expertise.  The wires often break off.  Only five pins of the six are used.  I may be able to respin the board this connector must be on.

I'd like to replace it with a Micro-USB B receptacle so that I can cut open easily-obtainable Micro USB cables and mate them to a DB9 connector.  Is the 5th pin actually wired on most cables? I don't know much about the USB standard.  Does this seem like a decent idea?

EDIT: This port is factory accessible only.


texts: Why do some PCBs have exposed copper along the edge even when mounted in plastic enclosure?

texts:
I've already read about reasons for exposing copper at the perimeter of a PCB (i.e. Why do some PCBs have exposed plated perimeters?).
It seems that the main reason to completely expose the copper along the edge is to provide a seamless connection to ground when using shielding covers or shielding metal case soldered/attached to the PCB.
But I wonder why some PCBs have exposed copper (here on top copper layer near the perimeter, contrary to sideplating) even when they are mounted in a plastic enclosure like in the pictures below? (PCB of a Valve Steam Controller)


texts:
Referring to the XC8 user manual, DS50002053E, section 2.5.10.3 the following is stated:

  For 8-bit compilers, change any occurrence of the interrupt qualifier
  e.g., from:

  void interrupt low_priority myLoIsr (void)

  to the following:

  void __interrupt(low_priority) myLoIsr(void)

Here's a simple piece of code I wrote:

void __interrupt(high_priority) isr_high (void)
{
    // IFC
    if(INTCON3bits.INT2IF)
    {
        TMR0 = TMR1 = timerZero;    // Reset the IFA and IFB counts
        ++ifc;
        ifa = ifb = 0;
        LATEbits.LATE0 ^= 1;
        INTCON3bits.INT2IF = 0;
    }
}

And here is a piece of sample code that the XC8 manual offers in section 2.5.10.1:

__interrupt(low_priority) void getData (void){

    if(TMR0IE && TMR0IF) {
        TMR0IF = 0;
        ++tick_count;
    }
}

Unfortunately I cannot get the code to compile.  Here are some relevant compiler errors:

(908) exit status = 1
Minion.c:215: error: (285) no identifier in declaration
make2:  [build/default/production/Minion.p1] Error 1
make1: * [.build-conf] Error 2
Minion.c:215: error: (1275) only functions may be qualified "interrupt"
make: *** [.build-impl] Error 2
Minion.c:215: error: (372) "," expected
Minion.c:216: error: (314) ";" expected*

Now, the manual is a little bit ambiguous because the section example in 2.5.10.1 shows the interrupt function identifier 'void' immediately prior to the function name, where as section 2.5.10.3 shows the void identifier immediately prior to __interrupt.  However, I have tried it both ways with no joy.

Someone else asked the same question here, but it was never answered to the OPs satisfaction or mine.

If someone has worked out the proper syntax for this, I would appreciate a share! If nobody is able to answer I will go back to the method I know works, which is shown in section 5.9.1 of the manual.


texts: Methods for converting PWM to +/- 10v Signal

texts:
Suppose we have a PWM signal which controls the speed of a motor and a digital pin which specifies which direction a motor is travelling in, how can we convert these signals into 1 +/- 10V signal where <0 is reverse and >0 is forward travel.

I appreciate there will be several ways of implementing this, but it's be good to consider different methods


texts: Does higher resolution of LCD/LED display mean higher energy consumption for the very same matrix size

texts:
If two mobile devices being compared have exactly the same LCD/LED screen (matrix) size and exactly the same battery, will the one with higher resolution have higher battery consumption and thus will require to be charged more often?

For example -- two Kiano tablets:

Kiano Core 10.1, 10 inches, 8000 mAh, 800x1200 resolution,
Kiano Core 9.7, 10 inches, 8000 mAh, 1536x2048 resolution.

Two devices, the same screen size and battery, resolution nearly twice . Which one should consume battery faster (in any), if both are used in the same way?

Which assumption is more correct:

Second device will consume battery faster, because it has much more pixels to power.
Battery consumption in case of both devices will be quite similar. Second has much more pixels, but since overall screen are a is the same, they're much smaller and therfore will use less energy to power.

I'm a beginner and layman (if not -- ignorant) in this area, so I'm much more convinced to the first assumption. But then, the fact that hardware producer decided to equip both devices with  the same battery, though different resolution, that would support second assumption.

Forgive me for asking in a wrong place (if so). But it is really hard to determine, where questions about mobile devices hardware should be asked on Stack Exchange network. I've seen this, this and this -- non of the answer says, where to ask such question. Both SuperUser and this site FAQ and both says that a question asked in an incorrect place, if it covers: "electronic devices, media players, cell phones or smart phones, except insofar as they interface with your computer". Bot non if these two sites expains, where such questions should be asked.


texts: Repairing broken trace on commercial board

texts:
A friend has a USB flash drive on which the SMD USB connector broke off.  When it broke, it pulled the pad traces off the board with the solder.  We are trying to think of a way to reconnect the traces long enough to recover the data on the drive.  We thought of filling the gaps in the coating where the pads were with solder, but one of them has an indentation that I am afraid would make solder flow onto a nearly adjacent component.

Any ideas for making a temporary connection?


texts: Looking for a component that turns like a potentiometer but produces switching signals

texts:
I have a preamp kit, it comes with 2 SMD buttons for volume up/down but I'd like to replace them with a turnable knob. Both the buttons share the same input, just the output goes on different legs of the main chip.

The component I'm looking for would have to have at least 3 pins and produce a series of switching between a common pin and one of the other 2 pins depending on which direction I turn. Pretty sure they exist, what are they called?


texts: Consequences of not following reflow profile

texts:
I found many questions about how to perform reflow soldering, but my main concern is

What are the consequences of not following the recommended reflow profile.
Would there be any risk going the approach I plan to take.

So, I have a board about 9 inch^2 and a hot air gun and Kester solder paste. When doing my first assembly I noticed that if I got the lead partially melted and then slightly cooled down, it is more difficult to re-melt it again. Also, it takes a long time to heat the  board with the hot air gun. I did not want to use oven, being afraid that I might overheat the components, whereas using a hot air gun would let me control local heating just to the melting temperature, simply by observing it. What I plan to do is to get a cheap oven at the store and preheat the board to say 180-200C. Then, use the hot air gun to finish the job.

I realize that the peak temperature must not exceed the maximum allowable temperature for components. I can easily ensure that. But how about the profile curve? The heating rates?

Regardless, whether using only the air gun, only the oven, or the combination of the two, I will definitely not be able to perform the task within 250 seconds as suggested by the profile. Neither, I will be able staying close to the suggested profile. So, again, what are my risks on not following the profile and is it worth combining the two techniques, or use exclusively one?


texts:
for some reason my DMA only seems to update ADC values once. I've set it up so that the callback function simply raises a flag everytime the DMA converts the ADCs, this flag only seems to go off once. I tried going through the example and I cannot pinpoint what I'm doing wrong. Hopefully someone can help.

void SysTimer(void) {
  ..
  PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_LPUART1|RCC_PERIPHCLK_USB|RCC_PERIPHCLK_ADC;
  PeriphClkInit.Lpuart1ClockSelection = RCC_LPUART1CLKSOURCE_PCLK1;
  PeriphClkInit.AdcClockSelection = RCC_ADCCLKSOURCE_SYSCLK;
  PeriphClkInit.UsbClockSelection = RCC_USBCLKSOURCE_HSI48;
  HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit);
}

void MX_ADC_Init(void) {
  ADC_ChannelConfTypeDef sConfig;

  //If I try to De-Init here first, I get an error

  hadc1.Instance = ADC1;
  hadc1.Init.ClockPrescaler = ADC_CLOCK_ASYNC_DIV1;
  hadc1.Init.Resolution = ADC_RESOLUTION_12B;
  hadc1.Init.DataAlign = ADC_DATAALIGN_RIGHT;
  hadc1.Init.ScanConvMode = ADC_SCAN_DISABLE;
  hadc1.Init.EOCSelection = ADC_EOC_SINGLE_CONV;
  hadc1.Init.LowPowerAutoWait = DISABLE;
  hadc1.Init.ContinuousConvMode = ENABLE;
  hadc1.Init.NbrOfConversion = 1;
  hadc1.Init.DiscontinuousConvMode = DISABLE;
  hadc1.Init.ExternalTrigConv = ADC_SOFTWARE_START;
  hadc1.Init.ExternalTrigConvEdge = ADC_EXTERNALTRIGCONVEDGE_NONE;
  hadc1.Init.DMAContinuousRequests = ENABLE;
  hadc1.Init.Overrun = ADC_OVR_DATA_OVERWRITTEN;
  hadc1.Init.OversamplingMode = DISABLE;
  if ( HAL_ADC_Init(&hadc1) != HAL_OK ) {
    errHandle(2);
  }

  sConfig.Channel = ADC_CHANNEL_TEMPSENSOR;
  sConfig.Rank = ADC_REGULAR_RANK_1;
  sConfig.SamplingTime = ADC_SAMPLETIME_640CYCLES_5;
  sConfig.SingleDiff = ADC_SINGLE_ENDED;
  sConfig.OffsetNumber = ADC_OFFSET_NONE;
  sConfig.Offset = 0;
  if ( HAL_ADC_ConfigChannel(&hadc1, &sConfig) ) {
    errHandle(3);
  }
}

void MX_DMA_Init(void) {
  __HAL_RCC_DMA1_CLK_ENABLE();
  HAL_NVIC_SetPriority(DMA1_Channel1_IRQn, 0, 0);
  HAL_NVIC_EnableIRQ(DMA1_Channel1_IRQn);
}

void HAL_ADC_ConvCpltCallback(ADC_HandleTypeDef* hadc) {
  adc_detect = 1;
}

ADC_HandleTypeDef hadc1;
DMA_HandleTypeDef hdma_adc1;

int main(void) {
  MX_ADC_Init();
  MX_DMA_Init();

  uint32_t adc[32];
  HAL_ADC_Start_DMA(&hadc1, (uint32_t *)adc, 32);

  while (1) {
    if ( adc_detect ) {
      adc_detect = 0;
    }

  HAL_GPIO_TogglePin(LD3_GPIO_Port, LD3_Pin);
  HAL_Delay(500);
  }
}

Edit (Solution): You need to init DMA before ADC because the HAL_ADC_Init file calls the HAL_ADC_MspInit, which configures your DMA. As such, you need to initialize your DMA channels before that.


texts: Measuring length of two wires inside copper with a TDR

texts:
I have a cable as in the drawing.
The black parts are insulators and the brown parts are copper, so there is a big copper cable and inside are two smaller copper cables.
When the big copper cable is tied to ground I can use a time domain reflectometer (TDR) on the smaller cables to determine the length of the cable.
What happens if the big copper cable is in use with a current running through it that is 1000 times bigger than the current running through the two smaller copper cables? Will I still be able to determine the length with a TDR?
I think there shouldn't be a capacitance between the two smaller copper cables - but how am I then able to measure with it a TDR?


texts:
I am genuinely sorry for posting such a basic, basic, basic question.

Moving to Thailand (220V) from Japan (100V). You cannot buy an extension cord in Thailand that is flush to the wall. Here in Japan, there are lots of angled extension cords from reputable companies that are flush. Most of these Japanese cords are rated at "1500W". If the only purpose is to connect a single 45W computer power adapter and nothing else, is it safe to use a "100V" Japanese extension cord without an intermediate step down transformer?

I have a basic understanding of electrical theory, which means I am fully qualified to burn my apartment building down to the ground. But I feel my neighbours would appreciate an informed opinion.


texts: how phase frequency matches in reverse power flow situation

texts:
I have a question regarding smart energy systems. Consider a reverse power flow (where the power flows from household to grid) situation, A household has a solar installation and the energy obtained is given to the grid. So the power from solar has one phase and the grid has the other. How the phase frequency of the AC power from household gets matched with the grid's phase frequency! Do they use any relays or something

Thanks in advance.


texts: Is there a pin header with 3mm pitch similar to the 0.1" pitch headers?

texts:
Is there a standard pin header with a 3mm pitch that is similar to the common 0.1" pitch pin headers (shown in photo below)? I'm not even sure what the correct name for these are. What is the best way to search for a part like this on Mouser or Digikey? My searches keep coming up with weird shrouded plastic housing things.
Thanks!

The part I was interested in connecting to is similar to this, with half-holes along the edges:


texts: What is the application of 1.2v ,60Ah NiCd(pocket type) battery now. Is it still in use in substations?


texts: calculate Amp Hours when voltage is given

texts:
I'm trying to wrap my head around how exactly Amp Hours work.
I have been trying to figure out this question for a while now, but can't seem to find the information that I need.

This is the circuit, and the information given is that the battery has 20AH capacity, and has a constant voltage 11.5 V. The question is to calculate how long it would take the battery to fully charge from being completely discharged.

What exactly is Amp Hours, and what is the formula to calculate it? I have noticed on many web pages that this is being calculated when the current of the circuit is given, but nothing about what to do when the voltage is given.

Edit: I know I can calculate the current in the circuit using ohms law, but I don't know what to do to calculate the time it takes to calculate how long it will take to charge to full.


texts: Is this a suitable Voltage Regulator to replace an old circuit on my board and is my logic correct?

texts:
I have 4 of these 2n3904 transistor setups on my board:

A1 -- requires 5v on these 2 connected pins to be enabled.
I control this by driving r2 high at 3.3v which should allow 5v to flow through the collector.
I am considering this alternative approach of using a sn74lv1t34dbvr
.
It appears I could drive this as follows where the ESP32 is the microcontroller I want to control power to the FSTD chip, via the SN74 regulator chip I have added to the circuit:

simulate this circuit – Schematic created using CircuitLab
Does this make sense? Is this correct? Would you recommend this approach rather than my original idea of using the transistor?


texts:
I know there are many questions floating about "howwant to drive a LED" going around (and many many good answers), but please bear with me.

The concern is how to make sure that my LED's don't have any sort of flickering, not even "micro-flickering" that's undetected by the human eye, as that can have health effects on both humans and plants (here are a couple of anlisys: https://www.digikey.com/en/articles/techzone/2012/jul/characterizing-and-minimizing-led-flicker-in-lighting-applications, https://www.azom.com/article.aspx?ArticleID=12161).

As I understand, LED micro-flicker may come from 3 sources:

Noise carried over from the AC line
Noise carried over from up-regulation of the AC frequency (present even in most high-frequency switching power supplies)
Flicker introduced by PWM for dimming

Here is my current prototype which should eat up about 72W if my math is right. I'm calculating the "ideal" Vf for each LED based on meassurements for the min and max Vf and max If, procuring the voltage never causes the current to exceed 76% of the max If. All the data of the components in link is according to reality.

I'm using the 12v rail of a PC PSU, because I thought "hey, this thing's used for powering micro-processors, it's gotta get rid of 1 and 2, right?" (though I haven't assertained that with an oscilloscope yet).

I'm guessing eventually I'll use a commercial 12v switching power (unless I realize that they all have problem number 2).

As for why I care about problem number 3, well, I'd very much like the lamps to be dimmable, quite possible controlling the diming from a micro-controller which (I hope) would be able to take the LEDs from fully-off (ie, just below the Vf) to fully-on (zero resistance, besides what I've put before each series).

Are there better ways to get a stable noise-free powerline? or to regulate the current programmatically without using a PWM?

Q: What is an efficient and cost-effective way to drive and regulate brightness for high-power LEDs ensuring a light output that's free of micro-flicker and as free of noise as possible?


texts:
I'm looking at a picture of an RF PCB meant to operate at a few GHz, and I'm having trouble understanding exactly what this is:

Obviously there are some transmission lines, and something that looks like a couple of radial stubs.
What are the little silver bits along the transmission lines, and in an arc around the radial stubs?  Are they vias, plated slots, or just bits of isolated copper? (At least some of it is not round.)  What function do they serve?
Also, what type of transmission line is this: microstrip, coplanar waveguide or SIW?
Note: It may be a bit hard to tell but most of the picture doesn't have copper on the top layer; the very bottom is a solid copper fill with soldermask, but the darker blue is apparently just substrate, and the silver parts are copper plated with something.  Sorry, I don't have a better picture, and I've never seen anything like this.
EDIT After @Dan Mills explained that this is chicken dots, I realize I have seen these before - there are usually a lot fewer and bigger of them, for example:

These look really useful for hand tuning.  Yay new thing learned :)


texts: I was reading an article over latches and suddenly a line struck me which says "D latches are also known as Transparent latches.". Anyone who can explain me why D latches are known as transparent latches. Thanks in advance.


texts: While I was trying to desolder a 6-pin header, the plastic holding the headers together melted. Now, that is fine, because I can pull out the individual pins that way, my question is, will the plastic melt onto the PCB, making it unusable because I won't be able to put new headers on?


texts: Can you use a gerber file and a pcb printer to make a stencil?

texts:
I need to solder a tiny 3mm by 5mm SMD. Thank fully my school has a reflow oven that can do the actual soldering part but I still need to acuratley get the solder paste on there. SO I was thinking of making a stencil.
We also have a laser cutting machine but it can't cut through metal and using other things like plastic, results in the "threads" between the pads being so thin that they break. (BTW is there anohter material like kapton film that could be cut super think and not break?)
So I was thinking if there is a way to manipulate a gerber file so that a PCB maching will cut out holes straight through the area where the pads should be.

For example, using the picture for reference, create a gerber file that tells the pcb machine to cut holes where the red pads are in the picture, not the red dots btw.


texts: RS485 Rx signal connected with two drivers

texts: I wonder why is RS485_Rx is connected with two line drivers while RS485_Tx is connected with only one line driver. Is this some mistake in the schematics or is it some standard circuit for RS485?


texts:
I've had a MSP430 for a very long time, but only recently got interested in it.

The chip in my MSP430 is a MSP430G2231, which according to http://energia.nu/Guide_MSP430LaunchPad.html I should be able to use with Energia.

But it doesn't show up in the board list, and when I try to compile the blink sample I get this error.

  Energia: 1.6.10E18 (Windows 10), Board: "MSP-EXP430G2553LP"

  :0:12: warning: missing whitespace after the macro name
  [enabled by default]

  Sketch uses 760 bytes (4%) of program storage space. Maximum is 16,384
  bytes. Global variables use 20 bytes (3%) of dynamic memory, leaving
  492 bytes for local variables. Maximum is 512 bytes. MSPDebug version
  0.22 - debugging tool for MSP430 MCUs Copyright (C) 2009-2013 Daniel Beer  This is free software; see the source for
  copying conditions.  There is NO warranty; not even for
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

  usbutil: unable to find a device matching 0451:f432 An error occurred
  while uploading the sketch

  This report would have more information with "Show verbose output
  during compilation" option enabled in File -> Preferences.

Not sure what I'm missing...

Device info:

New details:
Contacted the developer, and they sent me this:

  Please see the work-around for this in this thread:
  http://forum.43oh.com/topic/9848-energia-1610r18-windows-7-launchpad-msp430g2553-dont-load-sketch/?p=74156

  Will be fixed in the next core release.

Which has a work around to get this fixed:

copy \hardware\tools\DSLite\DebugServer\drivers\MSP430.dll to \hardware\tools\msp430\bin\
edit \hardware\energia\msp430\boards.txt an change the 2 occurrences of rf2500 with tilib
restart energia and you should be able to upload to the MSP-EXP430G2 with MSP430G2553.

Now I'm getting this error:

  MSP430_GetNumberOfUsbIfs
  MSP430_GetNameOfUsbIf
  Found FET: HID0016:COM5
  MSP430_Initialize: HID0016:COM5
  Firmware version is 20409001
  MSP430_VCC: 3000 mV
  MSP430_OpenDevice
  MSP430_GetFoundDevice
  Device: F20x2_G2x2x_G2x3x (id = 0x0035)
  2 breakpoints available
  MSP430_EEM_Init
  Chip ID data: f2 01 02
  Erasing...
  Programming...
  Writing  842 bytes at c000...
  tilib: MSP430_Memory: Could not write device memory (error = 7)
  MSP430_Run
  ihex: error on line 55
  tilib: MSP430_Run: Could not run device (to breakpoint) (error = 17)
  MSP430_Close
  the selected serial port MSP430_Close  does not exist or
  your board is not connected


texts: Simple analog circuit to simulate acceleration and braking behaviour in scale models

texts:
Background
Scale-model road systems such as Faller https://www.faller.de utilise vehicles that follow a ferromagnetic wire embedded in the road surface. The vehicles operate at full speed and continue until the on-board rechargeable battery runs out. There is limited remote control. At strategic places an electromagnet under the track can operate an on/off sensor in the vehicle.

Problem
This on/off behaviour - for example at a bus stop or road junction brings the vehicle to an abrupt and very unrealistic stop. The wheels are driven via a worm (screw) gear so the wheels lock when the motor stops.
Video showing abrupt stop and start https://youtu.be/emejjaj3c6E?t=411

Question
More complex and expensive digital systems are commercially available that simulate realistic acceleration and braking behaviour. Nevertheless, can I make a simple analog circuit to simulate inertia in these tiny vehicles?

My naive solution
I would like to put a capacitor in series with a resistor across the motor terminals. When battery power is switched off, the capacitor continues to power the motor until it is discharged. Likewise, on switching on the current, the motor starts slowly whilst the capacitor is charging. The component values can be adjusted to give realistic artificial inertia according to the size of the vehicle, e.g. Lorries will take longer to stop than cars.

Envisaged problems
Components have to be small (tiny) to fit on an HO (1:87) scale model. I think that I will need a huge capacitor to power the motor as it discharges. Is my idea sound - even in principle - or there another simple solution?

NOTE
These vehicles are only required to go in a forward direction - no reversing needed.

Many thanks.

P.S.
I'm thinking that by using a power transistor (op amp?) to detect the on/off switch, I could reduce the size of the capacitor and raise the value of the resistor by applying them to the input of the op amp. Haven't thought this through yet.

EDIT
Technical specs found so far:-

(a) I measured resistance across the motor terminals - 1 ohm

(b) The battery is a Varta V 150 H; Rechargeable Ni-MH Button; 1.2 V

(c) I was able to measure the current - 28 mA

(d) I found a circuit diagram (unofficial) http://simgw.cosmos.ehime-u.ac.jp/~shimizu/fallercar1/carsys032.jpg

EDIT
Electromagnets are mounted under the track at strategic points where a stop may be required, The vehicle is steered by a permanent magnet that follows the under-track passive ferromagnetic wire. There is a reed switch inside the vehicle that detects the on-or-off-ness of the electromagnet and disconnects the battery from the motor accordingly.


texts: Resistor on outgoing signal lines - the logic behind it

texts:
I've been reading a lot and also been advised to place a series resistor (order of 33 - 45 ohms) on outgoing signal lines. Also called a termination resistor I believe.
Example on this topic: Series resistor on digital signal lines
I'm wondering, what is the electrical aspect (theory) behind the resistor making the edges less 'peaky'. And also, it has been mentioned it is important to place the resistor as close as possible to the driver of the signal. What will change, and why, if it will, for instance, be placed more on the receiving side? (in case of a PCB that has no resistor on the driving side, will adding one on the receiving side make any difference?).
I could have responded to those topics but I thought a new topic for this particular discussion would fit better.


texts: Composition of sticky gel in Film Capacitors

texts:
Bit of a long shot here, maybe someone knows what the sticky clear gel might be inside common dual film can capacitors (motor run). I'm specifically looking for an MSDS.

This particular one was about the size of a soda can (dual 5uF/40uF 440VAC).

It is definitely not silicone grease- far more sticky and stringy (like hot glue when it is liquid) and has a slight odor. The closest thing we've seen is icky-pick used in telecom equipment. I have asked the manufacturer (American Radionics) but no answer as of yet.


texts: How to create complex copper shapes in Eagle

texts:
I'm new to eagle but for a project I need to create a pcb with a complex arrangement of exposed copper contacts.  The board is going to be used as a simple touch sensor made up of concentric and radial slices with each slice connecting to a separate pin (a sort of chopped up bulls-eye pattern).  We're making the board on an LPKF pcb router which takes in a gerber file generated from a cam file it provides for eagle.

Whats the easiest way to "draw" these kinds of shapes into a copper layer?
Thanks!


texts: Why are battery monitor ICs such as STC3115 (datasheet) called a gas gauge? This name seems pretty illogical and I was wondering the reasoning/story behind it.


texts: Are there blank prototype PCBs with staggered edges for a DB25 connector?

texts: Are there blank prototype PCB boards I can buy that will accept a solderable DB25 with its staggered pins?


texts:
I'm trying to hook up my 3 wire PT100 RTD probe to an Arduino, but end up out of my depth when it comes to the whole op amp circuit design. I have stolen the 1mA current source and wire compensation design from Precision Temperature Sensing with RTD Circuits, but as my RTD is good for -50 to 200C, the final stage isn't directly transferable.

Looking at a PT100 resistance table, at -50C resistance at the probe is 80.31Ohm and at 200C 175.81Ohm. With the 1mA excitation current that should give a voltage from 80.3 to 175.8mV as far as I can tell. Ideally I want to amplify and bias that signal so it roughly fits the 0 to 2.5V range the ADC is measuring, but I'm not sure how to do that. Another question I have is whether I want a low pass filter like in the application note, guessing it depends on the noise, particularly from the power supply (and AVR?). Note I don't have a -5V supply available, so it'll have to be a single source amplifier.


texts: My prototype is done, how to go to the next stage?

texts:
I have a background in software and for a while now I'm building prototypes with open source hardware.

I came to a point that I would like to produce one piece of hardware ie 'a device' from my prototype.

How do I do this? Where do I start?


texts:
I have a flyback transformer.  It has 2 outputs. I'm going to use one of them on a flyback converter.
Should I leave the second output of the transformer unconnected or connect a load to it?


texts:
I am trying to make a wireless door opener by adding a small Arduino with a relay switch into our home phone. Unfortunately, that home phone operates without a power source, it has wires for audio and for the door opener coil only.

The idea is: Since the door coil will not trigger with a small current, I could draw some power out of the coil circuit. I found that the coil operates on AC between 8 und 200 Volts.

The Arduino operates at 5V DC.

As a beginner in electronics,  I am unsure how to to this safely, while protecting the Arduino. Can you point me into the right direction?


texts: How does an optical mouse detect movement?


texts: How to make a sawtooth waveform look less like a staircase (DAC)?

texts: I am making a 4-bit digital-analogue converter using an adder circuit with four inputs. Each input is a square wave of a specific frequency. The output of the DAC is meant to be a sawtooth waveform but instead looks very jagged like a staircase. How could I make it look more like a straight line without changing the frequency of the square waves?


texts:
I'm using a high-frequency (1024PPR) RS-422 encoder, connected to a differential line receiver, and in turn, a quadrature encoder interface.

Initial tests were conducted with a low-PPR hand turned knob, where I could visually verify that the pulses were being counted correctly.

With a high-frequency encoder, how would I go about determining whether the counts are accurate? I should point out that the QEI is guaranteed to work at extremely high frequencies, so really what I want to be checking is whether the RS-422 receiver is correctly interpreting/outputting pulses, etc.


texts: ST-LINK Version 2 on Arch Linux not working

texts:
IMAGE LINK: https://ibb.co/yfFvwQP

I am using Arch Linux as my main os. I have just started embedded dev and am setting up my env.

I am having an error connecting to my St Link V2 debugger as shown in the snapshot I included. I used Stm32CubeMx to generate the code and Atollic as my IDE. I can build the project fine, but when trying to connect and debug I get a message that no device target is found which leads me to think I am missing some drivers/libs. I am unsure how to proceed as this is my first time setting these things up..

The st link USB has a red light that then goes to blue/purple; all the wires are hooked up properly - the board has a solid red light and flashing green light the CPU is the STM32F103C8T6

ERROR MESSAGE FROM ATTOLIC

STMicroelectronics ST-LINK GDB server. Version 5.1.0
Copyright (c) 2018, STMicroelectronics. All rights reserved.

Starting server with the following options:
        Persistent Mode            : Disabled
        Logging Level              : 1
        Listen Port Number         : 61234
        Status Refresh Delay       : 15s
        Verbose Mode               : Disabled
        SWD Debug                  : Enabled

Target no device found

Error in initializing ST-LINK device.
Reason: No device found on target.


texts: how to design an inductor in Tanner L-edit and extract the designed layout in L-edit to S-edit?

texts:
hello i am trying to design an inductor in L-edit.
i thought to use metal1 layer and make a squares in it for example 5 squares while there is a free hole in the center of them. actually i don't understand how it is an inductor.

second question is : when i am done with it and i use Tools-> extract and it makes T-spice code, how do i take it or the layout and use it in S-edit scheme.

i didn't find a good tutorial for that.

this is a tutorial (page 51 in the pdf), but it is not clear at all:
http://www.scribd.com/doc/72550091/29/Layout-of-Inductors

what i want to do in general is a BPF around 3GHZ.

thank


texts: Phase shift of voltage across capacitor in series RC

texts:
Here's a simple RC circuit from an AC analysis book:

simulate this circuit – Schematic created using CircuitLab

I'm trying to determine the phase shift produced by C1 relative to that of V1 given only frequency and impedance. In the book it says that the answer is -25 degrees. Does the negative sign mean that the current lags the source voltage, contrary to the fact that capacitances cause a leading phase shift?

EDIT: Or, does the negative sign signify that it's referring to the actual phase shift minus 90 degrees? Using the tangent relationship between the capacitive reactance and resistance, I keep getting 65 degrees for an answer.


texts: Post-synthesis simulation: Loading a custom standard cell library to a verilog compiler

texts:
I have a synthesized (gate level) netlist, and the cells that were provided to the synthesizer are part of a standard cell library I characterized on my own, out of transistor-level (post-layout) spice netlists.
How do I go about performing a post-synthesis simulation?
I have a .lib file, .lef file and the synthesized (gate-level) netlist.
Thanks in advance


texts: Arduino sketch not running startup method

texts:
I am trying to use the WiFly shield ( http://www.sparkfun.com/commerce/product_info.php?products_id=9367) with Aduino Mega board.

I am making modifications to the built in examples that ship with the WiFly. I have modified the sketch to make an http request to my personal server.

When I run the sketch through the USB port attached to my laptop, everything works fine. I can see the requests arriving at my remote machine.

When I try to run the board independently using batteries, I run into issues. Basically, the code in the "setup()" doesn't seem to be running. If I do a reset on the board by pressing and holding the push button on the Arduino Mega board, it also works fine. This proves that there is no error in the Sketch or back end server and that the hardware is also not broken.

So basically, when I start up the board via the first start up from a battery power source, it doesn't work. But subsequently resetting of the board using the power button on the mega seems to work.

Does anyone know why this is caused and how I can start running my sketch as soon as the battery pack is turned on (rather than having to do a subsequent reset?)

I had a look at the Arduino trouble shooting guide here http://arduino.cc/en/Guide/Troubleshooting2 and tried connecting the RX pin to the TX pin as well as connecting the Rx pin to GND via a 10k resistor. This doesn't help either.

Edit

I am running the sample WiFly sketch provided by Sparkfun from here. I changed the URL in the sketch from google.com to myserver.com and it works fine when running via USB connection to the laptop or after a reset. I have since added a 2000ms delay as suggested in the answer by kmort and that seems to work fine now. So it would seem there are "settling down issues" with the shield.


texts: RFID system for insect tracking - range of reading

texts:
I am planning on conducting an insect-tracking experiment in the field. We are going to have square enclosures (15m x 15m), where our insects can move around freely, but will not leave the enclosure. We want to track each individual (around 50 individuals per enclosure) throughout the summer season. I was considering PIT (Passive Integrated Transponder) tags glued on individuals, as it has been previously successfully applied to small size insects; however the reading range is way too short for our experiment (0.5 meters). I understand (hopefully correctly) that the same problem applies to passive RFID systems: impressively small tags, but range of readers too weak.

What would be your suggestion to achieve this reading range (15m x 15m), without making any sacrifice from the small-size of the tags?

For my experiment, the optimum size of tags would be smaller than 1 cm.

I apologize in advance for my lack of electrical engineering knowledge - it would have been a more informative question if I knew exactly what I'm dealing with and used the right jargon.


texts:
Gff is chosen so that it completely cancels the disturbance (Gff = -Gv/P) and Lp < Lv. Is it easier to control if Tp < Tv or Tp > Tv. I am a little bit lost on how to begin here? Should I look at the gains? Formulate the transfer function from v to y?
Edit: I realized I did not state that I can formulate the transfer function Gff(s):
\$ Gff(s) = -\frac{k_v(1+sT_p)}{k_p(1+sT_v)}e^{-s(L_v-L_p)}\$
I just do not know how this helps me answering "Which is easier to control?".


texts: Multi-channel data transmission system for Pixhawk autopilot

texts:
I hope to connect multiple Pixhawk autopilots to one PC, to establish a simulation system. In case you are unfamiliar with Pixhawk autopilot, here is a brief introduction:

  Pixhawk autopilot is an STM32F4 based controller for unmanned aerial vehicles. It is equipped with interfaces including UART, CAN, SPI, I²C, et al.

Now I have up to 50 Pixhawks, and I want to connect them with one PC. The data transmission between Pixhawk and PC needs to satisfy:

Each Pixhawk sending data @6.4 kbit/s and receiving data @25.6 kbit/s, at least.
The PC needs to distinguish who the sender is, i.e. to distinguish which Pixhawk sent a certain datagram.

Since the add-on development of Pixhawk is hard, I am not going to use the CAN or I²C interface of the Pixhawk. My plan is, to add another chip or board between a Pixhawk and PC, just like:

So, my question is:

What chip should I choose to finish this task?
Is the UART communication between Pixhawk and the chip okay?
What kind of bus should I choose?


texts: How to make a home intercom system with two corded phones powered by house current

texts:
I have an old cottage with a boat hoist at the end of a dock. The electrical power to the dock and hoist is controlled by a switch in the house.  Sometimes this switch is forgotten when taking the boat out, or is mistakenly turned off by someone who stayed behind while the boat is out making it impossible to lift the boat upon return. Rough waves from passing cargo ships can beat my boat to pieces in the slip if I don't lift it in time. Since cell service is not so great where we are what I would like to do is to place a phone (in a weather proof box of course) at the dock and another in the house.  Essentially making a sort of Ringdown phone.  I have found diagrams where this is done with a 9v battery; however, since my experience in the Marines has proven that batteries are always dead when you need them most and the house current is never shut off I'd like to wire in power there which both phones would operate from. Also these diagrams I've found don't allow for any kind of ringer or buzzer, that is imperative to get someone's attention ideally by just picking up the handset and the ringing or buzzing ceases when both are "off hook". The house and hoist are a little less than about 200 feet apart.   Cutting, crimping, and soldering I can do; it's not blowing it all up or starting a fire where I have problems; Marine.

Side note: The house has an existing phone line left over from when it was a year-round house which is not used anymore; it's still hooked up but can't make or receive calls. Could I just patch in an extension and run the line to the dock?  Would that be easier? How would I make the phone ring?

Thanks.


texts:
This is my first time asking a question here, so please be gentle?
I understand the theory of how mosfets work, but I'm having a lot of trouble deciphering all of the data sheet terms, to pick the right one.

I will be using an attiny85 to drive the mosfet. I have 3.3 volts with a maximum current of 4mA, to drive the gate. The circuit that I'm trying to switch on has a maximum of 24vdc, and a max current of 30mA.

My project will be positioned outdoors, so ambient temperatures will most likely range from freezing cold to 110 degrees Fahrenheit.

Any suggestions as far as Rds On (Max) @ Id, Vgs, or Vgs(th) (Max) @ Id, or Gate Charge (Qg) (Max) @ Vgs ranges?


texts: What is the source of reactive power generated by the alternator?

texts:
We know an alternator or in general any source of energy does not generate energy but converts one type of energy into some other usable form.

An electric generator produces both real and reactive power. The source of the real power is super heated steam, diesel engine or running water.

But what is the back source of the reactive power generated by the alternator, say if operating alone without any compensation devices.


texts: Equivalent input admittance problem - how to confirm with LT-spice

texts:
I had the following problem.

Consider this circuit:

Okay, so I think I solved the problem correctly (?) I start with creating equivalent impedances of the outer components.
\$ Z_1 = \frac{5 \Omega \cdot \frac{1}{j \cdot 220\text{nF} \cdot180\text{kHz}\cdot 2\pi}}{5\Omega+\frac{1}{j \cdot220\text{nF}\cdot180\text{kHz}\cdot 2\pi}}\$
\$Z_2=2\cdot(\frac{1}{j \cdot 750\text{nF} \cdot180\text{kHz}\cdot 2\pi})\$
\$Z_3=\frac{Z_1 \cdot Z_2}{Z_1+Z_2}\$
Now, the two inductors and \$Z_3\$ are in series.
\$Z_4=2\cdot(j\cdot 5\mbox{uH} \cdot 180 \mbox{kHz} \cdot2\pi)+Z_3\$
At last the 47nF capacitor is in parallel with \$Z_4\$.
\$Z_5 = \frac{\frac{1}{j \cdot 47 \text{nF}\cdot180 \text{kHz} \cdot 2\pi}\cdot Z_4}{{\frac{1}{j \cdot 47 \text{nF}\cdot180 \text{kHz} \cdot 2\pi} + Z_4}} = 1.822 \Omega + 21.0117j \Omega\$
\$Y=1/Z=4.0969 \text{mS} - 47.237j \text{mS}\$
So the conductance is 4.0969mS and the susceptance is - 47.237mS.
I really want to double check this, and I don't know how to do it in Lt-spice. Can anyone help me with this, or maybe confirm that my answer is correct?


texts: Can high voltage power lines EM provide power for drones?

texts:
How is the EM field that surrounds high voltage power converted to produce a current through a wire? How much electricity can be produced without coming in contact with the wire?

Could the EM field be used for a guide to travel along by sensing the field strength? Could a drone battery stay in float mode while traveling along a power line?

The drones would act essentially like a transformer loop connected to the transmission line (which can also be seen as a transformer loop) through electromagnetic induction.

Florescent lights powered by EM field.

http://www.scienceprog.com/the-bright-field-with-thousands-of-fluorescent-lights/


texts: How to highlight net when selecting a net in the PCB Panel?

texts:
When I am in the 2D PCB mode in Altium, I want to be able to select a net from the Net Classes, so that Altium will show that net highlighted.

How to achieve that ? (holding shift and hovering over traces is not what I want, I want to select the desired net in the PCB panel so that Altium highlights the traces)

When I select a net, Altium zooms it only in.


texts: Can I create a verilog file to both simulate and synthesize?

texts: Recently I was reading a Verilog study book. I finally realized that a Verilog file may not be synthesizable, because some Verilog statements are for simulation use only. But I'm too lazy to make one file to create a module and another to simulate it. Can I mix both up in the same file, and if so, how?


texts: Wifi - How does channel difference between transmitter and receiver affect the signal/data?

texts: When scanning a channel for wireless signals it is of course possible to pick up signals from surrounding channels. What I'm curious about (and forgive my n00b-ish-ness regarding the physics behind how signals are received/interpreted) is does picking up a signal from an adjacent channel affect any parts of the signal or data, such as the received signal strength measurement?


texts:
I have a question that I'm not really sure how to ask, so here goes:

So I know there's such a thing as a power conducting slip ring motor, which I assume allows the passthrough of power through the motor to power additional devices. I'm looking to see if there's such a thing as a power conducting stepper motor, or some way to hack such a thing into life.

My project requires the use of 3 motors in total - two stepper motors and one regular motor. I have to use the stepper motors (I think) because I require precise control over the angles for each, and the angles have to be able to traverse 360 degrees (not necessarily more than that, but having a little give in either direction would be good).

The motors will be connected in parallel, and are set up like the following:

(power source) ===> (motor 1) ===> (motor 2) ===> (motor 3)

The device itself will work very similar to this (animated GIF):
http://giant.gfycat.com/ClearcutMajesticCirriped.gif

Where the first motor rotates over one axis and the second motor rotates perpendicularly. Each of those two motors require precise angular control, and again would need to go at least 360 degrees (as quickly and precisely as possible) but not necessarily more than that. Motor 3 does not, as in the gif it just spins relentlessly.

I'm new to motors.