texts:
I am currently working with machines and when I try to understand their principles in-depth, specifically in machines, I got to know that EMF is induced because of any of the two reasons:

1) Time-varying magnetic field.

2) Spacial changes in the magnetic field.

It is said in sources I referred that in transformers the induced EMF is due to the time-varying magnetic field and in generator or motor, it is due to spacial variation in the magnetic field.

I did not get why in generators or motor the field is spatially varying. The magnetic field there also varies with respect to time because of sinusoidal current flowing through them?


texts:
There are a ton of electronics retailers and suppliers on the internet, all selling components at (essentially) retail prices. But when big companies need to use digital components (batteries, cameras, motors, etc.) in their products, they certainly aren't going to, say, Adafruit and paying $40 per TTL serial camera.

I have a hobby project (involving swarm robotics) that will require me to build hundreds of little tiny independent electronic devices. Each device will be its own "SoC" (system on a chip) and will be complete with its own power source and TTL serial camera. I'm wondering what big electronics manufacturers do when they are designing some new product to sell in stores: where do they go for bulk rate componentry?

As a simple example: when Tyco makes a new RC helicopter toy to sell, I'm sure they don't buy the individual parts from online retailers like JAMECO and pay retail prices. So what do they do? Where do they go? What kinds of "bulk deals" are available to them?


texts:
I am asked to design a 4-bit signed multiplier using only combinational circuits. Verilog code.

I have designed a 4 bit multipler:

The Half adder module

module HA(sout,cout,a,b);   //for Half adder mux
 output sout,cout;
 input a,b;
 assign sout=a^b;
 assign cout=(a&b);
endmodule

The Full adder module

module FA(sout,cout,a,b,cin);   // for full adder mux
 output sout,cout;
 input a,b,cin;
 assign sout=(a^b^cin);
 assign cout=((a&b)|(a&cin)|(b&cin));
endmodule

The multiply module

module multiply4bits(product,inp1,inp2);
 output [7:0]product;
 input [3:0]inp1;
 input [3:0]inp2;
 assign product[0]=(inp1[0]&inp2[0]);

 wire x1,x2,x3,x4,x5,x6,x7,x8,x9,x10,x11,x12,x13,x14,x15,x16,x17; //wire range started from [1:17]

 HA HA1(product[1],x1,(inp1[1]&inp2[0]),(inp1[0]&inp2[1]));
 FA FA1(x2,x3,inp1[1]&inp2[1],(inp1[0]&inp2[2]),x1);
 FA FA2(x4,x5,(inp1[1]&inp2[2]),(inp1[0]&inp2[3]),x3);
 HA HA2(x6,x7,(inp1[1]&inp2[3]),x5);
 HA HA3(product[2],x15,x2,(inp1[2]&inp2[0]));
 FA FA5(x14,x16,x4,(inp1[2]&inp2[1]),x15);
 FA FA4(x13,x17,x6,(inp1[2]&inp2[2]),x16);
 FA FA3(x9,x8,x7,(inp1[2]&inp2[3]),x17);
 HA HA4(product[3],x12,x14,(inp1[3]&inp2[0]));
 FA FA8(product[4],x11,x13,(inp1[3]&inp2[1]),x12);
 FA FA7(product[5],x10,x9,(inp1[3]&inp2[2]),x11);
 FA FA6(product[6],product[7],x8,(inp1[3]&inp2[3]),x10);
endmodule

I think that is right, but now I need to extend it and add 2's complement at the end?


texts: How does Ohm's law extend to Z if Z is complex?

texts:
We know that impedance, Z, is complex.

I'm told that $$V = IZ$$ But that rearranges to $$Z = \frac{V}I$$

But both voltage and current are real numbers, so how can a real number divided by another real number give a complex number? What have I done wrong?


texts: What does "\$\cos(2t)u(t)\$" stand for in this context?

texts: The question in the above diagram asks for "steady state current to \$\cos(2t)u(t)\$" of the network. I'm not sure what \$\cos(2t)u(t)\$ is, in this context. Is it the transfer function? Or something else?


texts: How to avoid false detection when using IR object detection circuit?

texts:
I have a circuit to demodulate 2KHz Infrared pulsed light which is generated by 555 timer IC and its output drives an IR transmitter circuit, which is received by IR receiver located 10 cm apart which amplify the signal with a transistor and then the output signal from it goes to missing pulse detector circuit based on 555 IC. Because I need a high pulse when an object block the IR light path between transmitter and receiver, I have used Schmitt trigger Hex inverter to invert the signal after the missing pulse detector circuit. Please see the attached schematic.

This circuit works well except on the power on and power off conditions, where there are unwanted pulses on both the instances without any object blocking the iR light path. I am trying to find a way to avoid or remove those pulses without losing out the circuit above-mentioned ability. I have tried LM393 based comparator but it didn't help. I also tried RC filter to replace 555 missing pulse circuit but it only detect bigger object and does not solve the problem.
The unwanted pulses on power on and power off looks like as in screenshot below.

The zoom in of power on unwanted pulse is,
And the power off unwanted pulses in zoom in looks like,

What modification can I do to avoid these unwanted pulses? Or should I try a different circuit altogether?


texts: Is it possible to transmit half-wave signals repetitively, like repetitive "north" magnetic fields like going from 0-1 Gauss "north" and repeat however many times per second without going 0-north-0-south like a full-wave signal?


texts: Why is my 74HC04 not inverting my input?

texts:
My Situation
I have this:
https://www.tinkercad.com/things/gUv4whDvcO3-fabulous-crift/editel?tenant=circuits
Or if that fails:
Schema (I think this is right, I have not used schemas much before as I have only recently started my journey into electronics (Well, a couple of months ago, but I started with the basics then)):

simulate this circuit – Schematic created using CircuitLab
My Question
When the first dip switch is off, the output of the hex inverter is high - correct
When the first dip switch is on, the output of the hex inverter is also high - ???
Where have I gone wrong? I have checked with the multi-meter and the input is 5V or 0V, however it always gives my 4.64V of output power, regardless of the input. This means that my LED is always on! I have no clue on what is wrong here...
Thanks for the help


texts:
We have a lab that wants us to simulate an RC and RL circuit, and then a CR and LR circuit (series). From reading it is my understanding that reversing order of components results in reversing the action (ie frequency selection curve). In other words

LR=RC
CR=RL

Why is this?


texts: Are the headset microphone signals travel unbalanced way and how do they reject noise?

texts:
Below shows a dynamic microphone equivalent circuit:

As you see above, the microphone output is first converted to balanced circuit via the transformer. The signal then travels along the cable until the preamplifier. It seems the signal is splitted to bipolar by the transformer.
Here is another example.

But how about in headset microphones such as this one? I guess they are also dynamic mic type. But obviously there is no transformer or another circuit after the headset mic. Does that mean the headset mics are single ended unbalanced transmission? By transmission I mean the cable from the headset mic to the TRRS jack which goes into the smartphone audio port.


texts: Can't write anything on QUADSPI data register (QUADSPI_DR)-stm32l452

texts:
I am using stm32l452 and toshiba 4Gbit flash ic, and I am trying to write and read data from flash via quadspi. I achieved reading flash and manufacturar id from flash(with commands, not with using data register) but I am unable to write anything on data register. I am monitoring it on system viewer window while trying to write something on register and it just gets nothing. Stays at 0x00000000 all the time. Does anyone have any idea about what is wrong?

I am sharing the code part where I programmed qspi.

uint32_t QSPI_init(void)
{
uint32_t dummy=0;
uint32_t rx=0;

SET_BIT(RCC->AHB3ENR, RCC_AHB3ENR_QSPIEN); //QSPI clock signal

QUADSPI->CR &= ~(QUADSPI_CR_EN);    //  qspi disable

RCC->AHB3RSTR |= RCC_AHB3RSTR_QSPIRST; //force reset

RCC->AHB3RSTR &= ~(RCC_AHB3RSTR_QSPIRST); //force release

QUADSPI->CR |= (QUADSPI_CR_EN);   //  qspi enable

dummy = QUADSPI->DR;

QUADSPI->FCR |= 0x1F;   //flag clear register

QUADSPI->CR |= 0x01000310; // FCLK = FAHB/2 // 1/2 cycle shift // 4 BYTE TRESHOLD

QUADSPI->DCR |= 0x00000101; // CSHT ve CKMODE // nCS stays high for at least 2 cycles between Flash memory commands // CLK must stay high while nCS is high

QUADSPI->DCR |= (0x1C << 16); // memory size

QUADSPI->DLR |= 0x02; // 4 bytes are to be transferred

QUADSPI->CCR |= 0b00000001000000000000000110011111; //read-id   // WRITE MODE

//while(QUADSPI->SR & 0x20); /* Wait for busy flag to be cleared */

QUADSPI->DR |= 0xA0A0A0A0;  // DATA TO SEND

while(QUADSPI->SR & 0x20); /* Wait for busy flag to be cleared */

dummy = QUADSPI->DR;  //READ REGISTER
rx = QUADSPI->DR;

return rx;

}


texts: Calculate closed loop gain with Oscilloscope measurements

texts:
Using these reading from Agilent MSO-X2012a oscilloscope:

from this circuit:

How do you calculate the close loop gain using these measurements. I already calculated by hand and got Av = 11V.


texts: Explanation of ethernet transformer signals RDCT, TDCT, RXCT, TXCT

texts:
I have seen in a schematic that the RXCT and TXCT are connected to Ground but actually there is no connected no ground to the PCB:

Can anyone explain to me what do these signals mean and if it is a bug and there is no ground, should they be connected to GND?


texts:
I have designed a board that is acting weird when you touch the touch screen, turn on and off relays, and even if you touch any wire specify ground(on jacket of wire). I want to know how can I determine this is due to ground loop or not.
Below image show how power supply shift up (or ground) and down wile touch the screen.

you can see even better on my amplifier output which is only transimpedance amplifier with gain 1M.

This is only two layer board with ground plan on both top and bottom, as you can see on below image.
Please let me know if you need more information.


texts:
I have two identical devices, the Megger MIT525 5 kV Diagnostic Insulation Resistance Tester. One of them present this behavior:

When it is charging connected to the electric network, the device turn on and work, even charge the battery. However when it is unpluged from the network the battery is unable to turn on the equip.

I already interchanged the battery between the devices.

Looking the card I noted this SMT capacitors and I want to know if they are damaged, maybe it could be the cause of the problem.

In the device with the problem:

In the another card they are diferents:

I don't have experience in mounting surface. So I want to know if this is an indicator.

How to do I tell if ceramic capacitors are damaged?

Note: If somebody have the technical manual of this device or know how i can get it could be very useful.


texts: Astable 555 timing circuit (0.5 Hz and 50% duty cycle)

texts:
I am trying to build a timing circuit to generate a 0.5 Hz 50% duty cycle signal. In other words 1 second on, 1 second off, and so on...

I have searched a few places and found the following instructions but that did not work. http://electronicsclub.info/555timer.htm#dutycycle.

Any ideas?


texts: Trying to find out the voltage threshold for input of a GPIO pin in an FPGA development board

texts:
I need to use a camera module along with De1-SoC development board. Camera requires 3.3V to work and it provides outputs with a 2.5V output pin.

I am trying to find what is the range of voltages that the FPGA will detect. I can not find that information easily anywhere in the specifications or any datasheets. This is the only official help I have found in the DE1-SoC User Manual. If the detection range for '0' is 0V-1.5V, and for '1' is 2.2V-5V I should be able to just plug the camera straight to the FPGA. Otherwise I would need to add additional voltage shifters.

If someone could point me to where I can find information regarding the official input detection characteristics I would be very grateful.

This is the link to the De1-Soc manual, and this is cyclone V manual from which I am too trying to fish out that information.


texts: Wire connectors for Back of Push to Exit Button

texts:
The connection terminals on the back of these Request to Exit buttons seem to resemble what I can guess is a "compression lugs".  Not really sure what they are called and I'm not familiar with general strategy to connect wires to these types of terminals.

Without knowing the precise size, what is the type of connector one would crimp to end of a wire to securely connect to these type of lugs?

Product:
https://www.visionistech.com/en/product/exit-button-vis-7000/


texts: Getting error while opeing ".cfg" file with the XGCONF tool

texts:
I got some strange errors in ccs.

I'm using a cc2640r2f IC and downloaded there simple_periphal_oad_on_chip from resource explorer. Whenever I open the .cfg file with the XGCONF tool I get an error As:

  Description    Resource    Path    Location    Type Can't find import file: 'common/cc26xx/kernel/cc2640/config/cc2640_r2_csdk.cfg'.

Of course I checked the location and the "cc2640_r2_csdk.cfg" is at the location it says it is not.

If I choose a different tool to open the cfg file like xdc script editor then no errors are displayed.

My first question what exactly is the XGCONF doing differently than the xdc script editor when it opens the cfg file?
What are some starting points to do to find out what is causing this?


texts: Why do I need to use a power amplifier after using a voltage amplifier?

texts:
For example speaker systems usually use a small-signal voltage amplifier followed by a power amplifier.

However, couldn't I use a single voltage amplifier which gives me the desired voltage to drive the load, why is there the need to have two separate amplifiers? And also why is it called a power amplifier as opposed to just a voltage/current amplifier?


texts: What's an easy way to supply power to a breadboard without using batteries?

texts: There are a number of kits available (for example sparkfun's Breadboard Power Supply USB - 5V/3.3V and Breadboard Power Supply 5V/3.3V or Adafruit's Adjustable breadboard power supply kit -  v1.0) but these all come as kits. What is a common and easy of-the-shelf way for a beginner to supply DC power to a breadboard without using batteries?


texts: Does the antenna length differ between transmitter and receiver?

texts:
I bought this 433Mhz transmitter/receiver that has two different antennas included. I managed to solder the receiver antenna to the transmitter. Is this a problem?

Shouldn't they have the same length since they work on the same frequency?

Edit:
I found the technical difference between the antennas:

Transmitter: external antenna: 25cm ordinary multi-core or single-core line
Receiver: External antenna: 32CM single core wire, wound into a spiral.

Edit 2:
I contacted the seller and got the following reply (I calculated the lengths)


texts: Intercept SPI of RC helicopter controller

texts:
I've got this radio communication with an RC helicopter. I found that the RX on the heli is using an AVR MCU and a CYRF6989 2.4Ghz chip to communicate with the controller of the heli and translates it to drive the servos and motors.
The MCU and the CYRF chip communicate by SPI. I want to intercept and interpret the signal so I soldered some wires on it. I am able to read the signal (either MOSI or MISO) using an Arduino prototype board. But I am having trouble understanding/interpreting the datastream. So I need a different approach than reading only MOSI OR MISO.

My current situation is that the Arduino is the slave, and it will either read the MOSI or MISO signal, but I can't figure out how I would go about reading the whole 'conversation', so both the MOSI and MISO signal. The only thing I can come up with is to connect MOSI and MISO to 1 wire using a diode (so the MCU and CYRF chip on the RX board aren't getting mixed signals) and read the data flowing over that one wire with the arduino board (using the SPI pins of the Atmega 328P). So MOSI and MISO come in over the same wire, which shouldn't be a problem really, as MOSI and MISO will never occur simultaneously. But the problem with that approach is that I do not have an indication of the origin (MOSI or MISO?) of the signal. It would be the easiest to have to SPI buses on the MCU, but thats against principles of SPI and AtMega2560 doesn't have so either.

Basicly my question is, what is a good approach to intercept the SPI conversation, so I am more able to interpret its meaning?


texts: Meaning of symbol with three peaks and numerical value on PSU?

texts:
Any idea of the symbol marked in red in the picture below?

This is on a power supply of an "electric height adjustable desk frame".

Is this "use below or equal 2000m altitude" due to smaller dielectric strength of air at higher altitudes, as explained in How does altitude affect AC-DC power supplies?

Any recommended website to look for such symbols?

Thank you


texts: tone() and reading data from serial are colliding

texts:
In my sketch main loop I used SoftwareSerial in order to read data from gps.

void loop()
{
  while (nss.available())
  {
    if (gps.encode(nss.read()))
    {
     ...

Also I have timer ISR, which is called every second or so, where I engage buzzer

ISR(TIMER1_COMPA_vect)
{
  tone(8, 1000, 200);
  // digitalWrite(9, 1); delay(200); digitalWrite(9, 0);

}

The problem is, when I hear the tone and at the same time there is an incoming gps data, the tone is corrupted. When data is finished the tone is clear. So somehow serial input and tone are interfering with each other.

Even without the code, that is reading data (nss.available() and nss.read()), if I just comment out nss.begin(57600); then the problem is solved.

How can I solve this?


texts: From how wide a range of angles can a grid of dipole antennas efficiently receive a power beam?

texts:
This paper on solar power satellite concepts makes brief reference to the ground receiver receiving an elliptical beam due to the angle it is at to the transmitter (2nd paragraph). The angle isn't that steep, some 35 degrees, and it would always receive from the same direction, so the dipole antennas could be spaced ideally.

In looking at power beaming in a similar fashion for the Moon*, the solar power satellites would move relative to the ground station, and so it would have to be able to efficiently receive power from a range of angles when the satellite was in range, and the angle would continuously change. Over what range of angles can a large grid of dipole antennas covering the ground be efficient this way?

* I'd appreciate not getting into whether space solar power is a good idea. This is for a work of hard science fiction, I'm just trying to draft the system correctly.


texts: Approval before I modify the form factor of an ATX PSU

texts:
I want to use an ATX PSU with my home build 3d printer but there is not enough space to fit it because of the height. Initially while designing the printer I planned to use an LED strip PSU. Now I realized when I opened the ATX PSU that there is enough free space after the fan mounted at the top is removed. I am planning to replace the big fan with two small ones mounted at the sides and then cut and refold the metal casing to the height just enough for the internal components.

I am making a big mistake?
what safety issues should I be worried about?


texts:
I wish to solder this type of HDMI connector (Datasheet) to matching pads on a PCB:

So half the pins are protruding out into the clear, and that row is easy to solder.

But just behind that row, as you can see, the 2nd parallel row with the other half of the pins are located inaccessibly underneath the body of the connector.

How can I do this soldering job?

Using a soldering iron, I wouldn't be able to reach there obviously.
Would this require using a hot air gun to apply heat from the underside of the board?
Or if I have to use an oven, can I apply solder paste and place the connector as-is on top of the pads? (The connector doesn't have any special thermal-protective tape.)


texts:
Diode voltage changes with temperature according to the Shockley diode equation.

I understand this , but what I don't understand is why diodes have a negative temperature coefficient (why voltage decreases with temperature.)

The temperature (T) is in the numerator of the equation so it should increase.


texts: Determining conductance / capacitance and inductance per unit length

texts:
How do you determine conductance / capacitance and inductance per unit for a cable experimentally?
Is there a way to determine them with only a oscilloscope and a pulse generator?


texts:
For the longest time I have been instructed to put on 100nF decoupling capacitors between the VCC and GND pins whenever I lay out a board involving an MCU. I could not find the exact reason as to why they are needed. However, after some research online I did find a few reasons for their use. Below I explain the main reason, as I understand it, why decoupling capacitors are needed. I would like some feedback and would also like to know if this explaination is satisfactory or not.

Consider a pin of an MCU which has a single LED connected to it through a resistor. Lets say that the pin toggles from low to high, that is it turns the LED on. Now with the LED on, it will draw current which the MCU will have to provide. In return, the MCU draws more current (i.e power) from the power supply i.e. its VCC and GND pins. However, a sudden current draw by the power pins causes a voltage drop across the resistance of the power traces. Since the power supply is slow as compared to the microcontroller, it senses the drop in voltage after a little time and then changes the voltage back to its constant value again ( since it is to behave as a constant voltage source). That is where the decoupling capacitors come in. Whenever the MCU draws in a current pulse, the capacitor makes sure that the voltage across the power pins remain essentially constant till the power supply voltage stabilizes again.

That is all I have understood. Now I do not know how to calculate the exact value of the decoupling capacitor but have been told that 100nF or any value in that neighbourhood is pretty safe to use.

I am waiting for your comments.


texts: Speaker wired in parallel & connecting to stereo amplifier

texts:
I just bought two 2-way in-ceiling speakers (Yamaha NS-IC800). Each of them is rated at 8 ohms. I wired them in parallel (so it's 4 ohms in total):

The amplifier I will be using is Nobsound NS-20G which supports 4-8 ohms:

However, here comes the confusion. Since I only have a set of wire (1 red 1 black) due to parallel wiring, am I supposed to wire both of them to just the right channel or to just the left channel, or am I supposed to wire 1 red to right channel and 1 black to left channel?
The latter seems to be sensible given that I need stereo audio (not mono.)
However, I then discovered that doing this means that it's bridged and hence it is mono.
Not to mention the issue with the increased watts due to bridging (the amplifier has 100W x2 ratings) while the speaker only need 50W RMS per side so this setting could potentially damage the speaker.
I must have gotten or understood something wrong here.


texts: Can you recommend a good schematic or module of a Bluetooth + Wi-Fi combo?

texts:
I have found couple Bluetooth+Wi-Fi modules, but they are in the $20-$40 range - which is, for my opinion, too expensive. I am interested in seeing/reviewing a finished (as in proved to work without problems) schematic of a combo of bluetooth and Wi-Fi modules.

Even if it is not a combo, then two separate schematics - which can be safely integrated. Also, if I would to have them both on one PCB, can I use a single PCB trace antenna? (only one is on at a time).

Lastly, what would you recommend - trace PCB antenna? or chip antenna?

Thanks


texts: Power efficiency on mini hydro generation

texts:
Here is the generator I intend to use on my project which I obtained from this site.

(source: seeedstudio.com)
Could you help me to get a tip/direction on how to start the calculation for this. I search some (might be wrong), I would need to calculate/measure the head and flow. but I don't have the flow. also the device's efficiency isn't also listed on its parameters.
This is the description of this generator given by the seller:

Unique hydropower separation technology, the unique dual clutch, magnetic circuit coupling volume is only about 4/5 of the normal micro hydroelectric generator, the output power to ordinary hydroelectric generator 2-3 times.

High efficiency, long life of waterway design and low flow loss, low water pressure (0.5 KG), load short circuiting, also can start smoothly

The specifications supplied by the seller are shown below but these do not match those given for apparently similar units sold by other sources. I bought the unit from a local seller due to difficulties with importing them in my situation.
Maximum working pressure: 1.75MPa
Working pressure: 0-1.75Mpa
Test pressure: 1.2MPa
Temperature range:-0-120 degrees Celsius
Flow range: 1.5-20L/min (press 0.05-0.2MPa)
Maximum output voltage: 5v VDC
Maximum water flow rate: 10L/min
Shell material: nylon
Weight:200g
Sold by
Thank you so much for the help.


texts: What is the best type of magnifier to use for general electronics duties?

texts:
I am looking for a magnifier tool for an electronics workbench and was wondering what sort of product would be best.

The device must be an all-rounder capable of doing some SMT as well as through hole stuff.

I reckon that something like this would be about right, its a 1.75x 7' ring 28w magnifying lamp.  Is this going to be a usefull addition to the bench?


texts: Improve a simple “magnetic alarm” with a timer, to extend the ringing time

texts:
I've bought this simple "alarm" for a door:

Which is internally provided with a reed switch; inspecting the internal circuit using a multimeter, I figured out that when the magnet is placed near to the alarm, the reed switch is N/C; when the magnet is away from the alarm, the reed switch is N/O and this will trigger the alarm, however, when the door is closed again, and so the magnet will be placed again near to the reed switch, the internal buzzer of the alarm will stop to ringing. I'd like to extend the ringing time of the buzzer: So I had two ideas:
The first one, simple and dirt,  is to connect a very big capacitor (or a batch of capacitors) in parallel with the batteries of the alarm. The second idea is to replace the reed switch with a cyclic timer, here the schematic/wiring:

This seems a better idea, except for the fact that the timer will get the power supply (12 V) from a wall wart; so, in the case of a power failure in the house, the alarm will be unable to work (however the alarm itself is feed with a battery pack for a total of 4,5 volt); I could use, instead, the N/O contacts of the timer, but in this way, in the case of a power failure, the alarm will start to continuously ringing.

I would avoid an external and huge battery, mainly for a maintenance reason (charge and discharge).

Maybe could I act on the buzzer? Eg replace the onboard buzzer with another buzzer that would be able, by default, to ring for a certain time, maybe with a simple 9 volt battery..

So: can someone suggest me a failure proof solution?
Many thanks.


texts: 3KW SR motor gate driver and simulation questions

texts:
I'm designing power electronics for 3-phase 3KW SR motor by using power MOSFETS of rating 600V. To drive the gates of these MOSFETS, I'm using IR2183 gate drivers, one per each phase.

The DC voltage at the drain of MOSFET is directly from the DC capacitor link which supplies 300VDC.

Although the gate drivers should be in closed loop control system, for simulation purposes I’m using voltage sources for input pulses.

I have provided the circuit diagram and simulation results below. My question is, is this how the output current of an each phase looks like? And do I have to make any more changes to the circuit with higher inductance values (considering motor's inductance would be high)?

I would highly appreciate any suggestions provided.

Thanks in advance.


texts: Interfacing 5V to 3.3V for Xilinx Spartan 6 FPGA and vice versa

texts:
I am referring to high speed design with Spartan 6 FPGA.
My query is, in design I am having 5V compliant devices (ADC,FIFO memory) and want to interface with 3.3V FPGA spartan 6.

If I opt for simple resistor,diode termination... Is it good option considering sampling rate of ADC 400kHz.

I want to consider all aspects such as power consumption,speed etc in case for Resistor-Diode termination or even for level translator. Please someone help for my understanding.

Attached App Note Link: 5V Tolerance Techniques for CoolRunner-II Devices.
https://www.xilinx.com/support/documentation/application_notes/xapp429.pdf


texts: What is this electronics symbol (four triangles?)

texts:
The below image is from a service manual for a mobile radio. Note the small symbols that appear to be four triangles, point to point. I've searched far and wide and cannot identify that symbol. I have a nagging feeling that I've seen something like it in hydraulics, but never in an electronics diagram. I know that my radio doesn't have a bunch of stars of David printed inside it, so what could this symbol be?

Some of them have a line through the middle, others don't. Compare for example the ones near the labels "mic int" and "mic ext". Does this represent something, or is it a typo?


texts: Resistance and power requirements for a current-limiting resistor

texts:
I'm making my electronics project.

I need answer please
I need an resistor
I just need to clarify and validate.
Given

\$V_s\$-15 V
\$V_{LED}\$-3.5 V
\$I_{LED}\$ - 25 mA

I did:

R= \$\frac{V_s - V_{led} }{I_{led}}\$

= \$\frac{11.5 V}{25mA}\$
 = \$\frac{11.5 V}{0.025 A}\$
 = \$460 \Omega\$

And a power of 0.2875W, but I bought 470 \$\Omega\$ with 1 W

What will happen to my project?
Fail or burn the LEDs?


texts:
I'm trying to understand how non-blocking statements interact with certain procedural statements in Verilog.
If I have the following block of code inside a module
input clk;
.
.
.
parameter divider = 12;
reg [3:0] clk_counter = 0;
.
.
.
always @(posedge clk)
begin
    clk_counter <= clk_counter + 1;
    if(clk_counter == divider)
       clk_counter <= 0;
end

I understand that hardware description languages are not like procedural languages, and therefore it is a good idea to get out of the habit of thinking about them as if they were, but atm I am just trying to wrap my head around some of Verilog's behavioral constructs to make programming in it easier. With that said, here's my question
Will Verilog evaluate the right side of clk_counter <= clk_counter + 1; and then enter the if(clk_counter == divider) loop and use clk_counter's old original value (i.e., not clk_counter + 1) to evaluate the conditional statement?
Edit: My extraordinarily underdeveloped understanding of Verilog is showing. As was pointed out, the compiler isn't going to actually evaluate the conditional. I am aware of this. What I meant in asking my question was: can I assume that Verilog will build a circuit that will behaviorally mimic what we would consider to be an evaluation of the righthand side of clk_counter <= clk_counter + 1; and use ```clk_counter``'s old value (i.e., that stored in the flip flop) when evaluating the conditional. I am not experienced enough with the language to imagine what this circuit might look like because I am still working out in my mind how Verilog's behavioral constructs interact with each other.


texts: Use TVS and zener diode on the same circuit

texts:
In order to protect against ESD and overvoltage at a charger input, I would like to know if it is recommended to use TVS and Zener on the same circuit, if so, what would be the configuration?
The intention is to meet the requirement of IEC 61000-4-2, but also to protect the system if an unsuspecting person connects a charger of 12V or more, instead of 5V.
The Reverse Standoff Voltage of the chosen TVS is VRWM = 5V, and the Clamp Voltage for the TLP 16A graph is Vc = 11V.


texts: Can I replace a SMD capacitor with a wire

texts: I have a cheap device, which has blown one of its SMD capacitors (no markings) and I was just wondering that what will happen if i remove the cap and put just a jumper wire to its place?


texts: Trouble understanding OEM HP Sensor CB781-80006 circuit

texts:
I am having trouble understanding an OEM HP Sensor CB781-80006 circuit, I'm a beginner in electronics. Does anyone know to tell me what are the values ( VCC, GND, and outputs ) this sensor was removed from the old printer hp I want to use 3v in the input I will connect it with raspberry pi
Thank you


texts: Does the electric field travel mostly on the surface of the copper in a standard circuit?

texts: I just learned the thing that travels at the speed of light when you flick on the light switch in your home is the electric field. The electrons travel through the wire about a snails pace BUT since the entire wire is chuck full of electrons the EMF force or voltage is felt at the speed of light as soon as the electric field hits the electrons and they begin their snail pace drift venture .  I read somewhere that the electricity flows mostly on the copper surface. Are they talking about the electric field or the drift that is mostly on the surface?  I assume since the larger the wire the greater the EMF that can be forced through that they mean the electric field.    Since it is not possible to have an electric field with out a magnetic field is a radio wave being sent out each time an electric circuit is turned on and if so WHY DOES IT NOT transmit continuously ? Very puzzling to me. Thank you


texts: Restarting ESP8266 NodeMCU in DeepSleep with a signal from HM10 BLE

texts:
I'm building a simple project in which I put the ESP8266 NodeMCU board in DeepSleep mode, so I can save some battery since it's powered with 4 AA batteries.
What's the problem?
I don't want my ESP to wakeup in every x seconds, I want it to only wake up when the HM10 receives a signal.
I had a HC-05 bluetooth module before, in which I connected the TX to the RST pin of the ESP8266 to force it to restart and that was working fine, but once again due to power saving I decided to switch from de HC-05 to the HM10.
So the wires between the HM10/HC-05 and the ESP8266 NodeMCU are the following:
HM10/HC-05 - ESP8266 NodeMCU

VCC - 3.3V
GND - GND
TX - RST/EN

I did some tests and I got the following results when the ESP8266 is in DeepSleep:

HC-05 TX connected to RST pin: OK (esp8266 restarted)
HC-05 TX connected to EN pin: Nothing happens
HM10 TX connected to RST pin: Nothing happens
HM10 TX connected to EN pin: Nothing happens

And when the ESP8266 is just running without DeepSleep:

HC-05 TX connected to RST pin: OK (esp8266 restarted)
HC-05 TX connected to EN pin: OK (esp8266 restarted)
HM10 TX connected to RST pin: Nothing happens
HM10 TX connected to EN pin: OK (esp8266 restarted)

So I find this behavior a little bit weird. Is there any simple explanation for this?
Conclusion: I just need my HM10 BLE to be able to restart the ESP8266 when it is in DeepSleep mode.
My HM10 BLE is this one: https://www.amazon.es/gp/product/B07NJ1881X/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1


texts:
I am currently working on a simple AC Mains Indicator and would love to have a blown fuse indicator on my primary circuit.

After some searching on google, I came accross this circuit:

http://electronicsforu.com/electronics-projects/blown-fuse-indicator

What I'd like to know is what kinds of LED (the red and green ones) should I use here? Can I use the typical 5mm LED lamps?


texts: What is a good way to reinforce wire soldered to solder lugs?

texts:
I have a number of different switches, all with solder lugs more or less similar to this:

I have soldered some stranded wire to it, using a method I found in a video where the stranded wire is stripped, the exposed strands twisted and soldered together, then put through the hole in the lug and soldered to the lug. The electrical connection works great, but I worry about the mechanical stress on the connection. Here is a picture of the soldering job itself:

I can easily bend the wire 90 degrees from the contact point if I wanted to, which doesn't give me much confidence in the mechanical strength of the connection. Is this a job that shrink wrap/electrical tape could fix? Or should I be soldering this differently?


texts: EMC shielded box with transparent window?

texts: Is there such a thing? I would like to put my board in a box to isolate it from radiated emissions externally and also limit emissions from the board to the outside. I would also like a transparent window. Is this possible? [Thinking conductive coating, fine mesh etc]


texts: I have connected my relay with a nodeMCU so that when I give commands to relay through nodeMCU the led connected to relay gets powered up. But after proper connection also it doesn't power up.


texts: Simulate capacitive touch sensitivity and noise immunity

texts:
Due to covid, we are limited in the time we can tune our touch designs before EMC tests.
The device we are using has a PC based analyzer that is connected to the device over a serial protocol. Normally we use this analyzer when tuning for sensitivity and noise, but we are now forced to use simulation software as much as possible.
Is it possible to emulate a physical device by sending capacitance values from our simulation software to the analyzer and then tune the device based on this data?
The simulator we are using is COMSOL, and we are using Microchip touch devices.


texts: Using a compartator to make an LED light up. How do I make the LED light up?

texts:
This is my circuit that lights up an LED for less than 4 seconds of volts using 4V. How do I make the LED light up? I thought the output of the comparator was the comparators supply voltage, and that current would go through the 330 ohm resistor R5, and then the LED.

1) is what I tried

2) is something I saw, tried, and it didn't work.


texts: Is it standard for a VSD to pull its power from the controlling PLC? Is this the better solution?

texts:
We have an industrial floor that is opened and closed by a variable speed drive motor. This is controlled by a PLC device. Recently we had to do maintenance on the VSD. The serviceman incorrectly diagnosed that the VSD wasn't working because the battery had died. We had the VSD serviced and its all working again. The problem was with the VSD. However we determined it wasn't the battery since it was drawing power from the PLC.

I'm interested to know if it is common for this type of configuration? Should the serviceman (he was employeed due to claimed extensive knowledge of such systems) have known about this?

sorry I can't provide the hardware details of the VSD/PLC don't have these handy.
I will try and get the specific config details this weekend.


texts:
I'm new in the forum so sorry if my question was already previously asked. I tried to use the search function but I was not happy with the answer I got. So I have fun doing the light designer sometimes. I often see LED lights that are for instance 18x15 (270W). However when tested, the actual current consumption turns out to be less than that (about 200W usually). I've never been able to figure out why. Thanks guys and have a good day.
Leo


texts: Mathematical proof that RMS voltage times RMS current gives mean power

texts:
I know this is true because I read it in a reputable source. I also understand intuitively that power is proportional to the square of voltage or current for a resistive load, and that the "S" in RMS is for "square". I am seeking a hard mathematical proof.

Let \$I_i\$ denote the current at instant \$i\$, and likewise \$V_i\$ denotes the voltage at that instant. If we can measure voltage and current at all the instants, and there are \$n\$ instants, then mean apparent power is:

$$ P = \frac{1}{n} \sum_{i=i}^n I_i V_i $$

What is an elegant mathematical proof that

$$ P = I_{RMS} V_{RMS} $$

achieves the same result for resistive loads?


texts: Seeking  replacement for TA7279AP dual full H-bridge

texts:
I am searching for a dual full  H-bridge chip with separate load voltage inputs for each bridge and high impedance state for outputs when idle. The TA7279AP is perfect but is being phased out.
The closest component I have been able to find is SemeLab IP3M10, but it does not have a state with both outputs at high impedance.

Requirements are 8 to 24 volts, and each bridge able to handle up to 100mA. TTL control logic.
Thanks in advance for suggestions about possible replacement components.


texts:
This question is in the context of using verilog/systemverilog for synthesizable RTL.

I have some vector signals that are going across module boundaries that are currently defined as inout ports.
The reason they are inout ports is that some of the vector indices are assigned in some places within the hierarchy, while others are assigned elsewhere.
However, it is hugely beneficial to be able to consider these as one large shared bus that can route to many locations.

The problem is that I am using these inout ports in synthesized RTL and some of the backend tools have issues with these inouts when it comes to low-power synthesis and logical equivalency checking.

There is really only one driver ever to these signals, so they are never really needed to be inout.  The problem is just that some indices would be ideally marked as input, while others are marked as output.

In the past a solution has been to use sparse vectors, one for each hierarchical location that could be assigning one of these indices.  Then, they are all combined, using generate blocks and location masks to determine how to map each of the possible drivers to the final signal.

This approach ends up being a lot of overhead and requires doing some level of masking/mapping at each hierarchical location, and all of this is only to avoid having singly-driven ports defined as inout direction.

Since my backend tool flow requires not using inout ports in this scenario, does someone have another approach that may be more coding efficient?

Here is some sample code to illustrate (untested):

My ideal code is as follows:

module driver0(inout [1:0] sig);
    assign sig[0] = 'b1;  // drive with some real value
endmodule

module driver1(inout [1:0] sig);
    assign sig[1] = 'b1;  // drive with some real value
endmodule

module top();
    wire sig[1:0];
    driver0 u0(.sig(sig));
    driver1 u1(.sig(sig));
endmodule

No bits of the sig vector are multi-driven, they are just driven in different modules.

My non-inout solution is follows:

module driver0(output [1:0] sig);
    assign sig[0] = 'b1;  // drive with some real value
    assign sig[1] = 'b0;  // clear unused indices
endmodule

module driver1(output [1:0] sig);
    assign sig[1] = 'b1;  // drive with some real value
    assign sig[0] = 'b0;  // clear unused indices
endmodule

module top();
    wire [1:0] sig, sig0, sig1;
    driver0 u0(.sig(sig0));
    driver1 u1(.sig(sig1));

    assign sig = sig0 | sig1;
endmodule

It requires having a temporary sparse vector for each possible driver and then combining them.
This was just an example with a 2-bit vector and two drivers.
You can imagine that it takes quite a bit more effort and wasted code when the vector is large, as it requires looping over each index and then having some mechanism for determining which bits are driven in each hierarchical level.


texts:
I'm using an Airwave 663 module. It's a 5.8GHz FM video + stereo audio transmitter module. Here is the datasheet: http://www.airwave.com.tw/specification/RF%20modules/AWM663TX.pdf

It is apparent that the module requires a 470uF 16V capacitor on the BYPASS pin. Compared to the other components on my board, this is absolutely massive. But I can't find any specification anywhere about what this capacitor does and whether or not this capacitor can be made smaller.

If anyone here has dealt with similar modules, what was your expereience?


texts: Calculating SD card size from C_SIZE in CSR

texts:
I'm guessing I'm just reading something incorrectly here, but I can't make this add up.  From the SD card spec, section 5.3.3 tells us how to calculate card size (C_SIZE) from the data in CSR (CMD9 response):

So first, my "32GB" card gives this value as 0xE9E5 = 59877.  Okay, so then my card is
59877 * 512 * 1024 = 31393316864 bytes

if KBytes means 1024 bytes... does it?  But more confusing for me, the first minimum value given, "minimum user area size of SDHC Card is 4,211,712 sectors."  Just below that in the spec, it says that a sector is 64KBytes, so then the minimum for an SDHC card is
4211712 * 64 * 1024 = 276018757632 bytes

or... 257GB???  That is clearly incorrect.  So where am I going wrong?
EDIT I found an answer to my question about the definition of KByte in this spec: section 5.7.2.4 has a bit map graphic that states that 32KBytes is (64 * 512 bytes).  So KByte is what I would imagine it would mean, even though the marketing speak that has cluttered up the storage world made me question this.


texts: What do people use to hold an object in place while being worked on?

texts: I would like to know what people usually do when trying to solder wires together, and hold small things in place while you fasten them together, etc.  I can picture one or more vices attached to a swivel such that I can hold something in place at any orientation, perhaps with an array of alligator clips attached to stiff wires to hold things in place.  Does anything like this exist?  And if not, what do people usually do to hold two things together while busying your hands with wielding a tool?  (considering us poor humans have but two hands.)


texts:
I've been looking deeper into the idea of performing feedback analysis for MOSFET differential pair configurations. This particular amplifier circuit has been giving me some trouble, where I am looking to find the closed-loop gain \$(v_{o}/v_{s}) \$:

The circuit states that the transconductances of the MOSFETs in the pair are equal but the transconductance of the 3rd MOSFET is not \$(g_{M1}=g_{M2}\ne\ g_{M3}) \$. Output resistances of the transistors are also taken to be infinity.
If we continue under the assumption that \$R_1=R_2\$ and perform our standard \$A\beta\$ feedback analysis, I arrive at the following equations:
$$A=-g_{M3}R_{eq}g_{M1}R_{1},\space\ \beta=\frac{R_5}{R_5+R_4}$$
where \$R_{eq}=(R_{22}||R_3)=((R_4+R_5)||R_3)\$ with the final closed-loop gain expression being of the form:
$$\left( \frac{v_o}{v_s} \right)=\frac{A}{1+A\beta}$$
Here is my issue. I do not see how the gain can be solved for unless \$R_1\$ is taken to be equal to \$R_2\$. This assumption allows us to convert the differential pair into a half circuit and makes solving the \$A\$ circuit relatively straightforward.
Is this a legitimate assumption though, or can the circuit be solved assuming \$R_1\ne R_2\$?


texts: How to implement different encodings for subsets some enumeration in VHDL?

texts:
When trying to decode/encode a large number of distinct 'things' in VHDL, I stumbled across the following technique, which I find quite intriguing:

TYPE things IS (A, B, C, D, E, F, G, H); -- requires 3 bit
SIGNAL encoded : std_ulogic_vector(2 downto 0) := "100";
SIGNAL decoded : things;
decoded <= things'VAL(to_integer(unsigned(encoded))); -- results in "E"
-- This is how encoding would work:
--encoded <= std_ulogic_vector(to_unsigned(decoded'POS(decoded)));

Now what if I want to encode/decode a subset of things like (A, B, E, F) with 2 bit? VHDL has the notion of subtypes. However, as far as I know, subtypes must be specified by a single range attribute and can not have 'holes'. Note that I can't simply change the order of the elements because the order is fixed and because there are different subsets with different 'holes' so eliminating all of them would be impossible anyways.

TYPE subthings IS things RANGE A TO D;                   -- works
--TYPE subthings2 IS things RANGE A TO B + RANGE E TO F; -- would be cool
TYPE some_things is (A, B, E, F);                        -- not a subtype

SIGNAL a : things;
SIGNAL b : some_things;
SIGNAL some_things_encoded : std_ulogic_vector(1 downto 0);

b <= some_things'VAL(to_integer(unsigned(some_things_encoded)));
a <= b;  -- Doesn't work although the literals are a subset.

Now the easiest way to convert from some_things to things would be to write a silly looking conversion function and use that to do the assignment:

FUNCTION to_things(x : some_things) RETURN things IS
BEGIN
    CASE x IS
        WHEN A => return A;
        WHEN B => return B;
        WHEN E => return E;
        WHEN F => return F;
    end case;
end;

a <= to_things(b);

Now this works, but it gets a bit tedious and verbose with a large number ob subsets and a large number of items. I'm not really into writing 20 functions consisting only of 32 nearly identical lines.

So I'm wondering if there is any more elegant and synthesizable way to do this, preferably without VHDL 2008, due to the poor tool support. Would something along the lines of the following work?

FUNCTION to_things(x : some_things) RETURN things IS
BEGIN
    RETURN things'VALUE(some_things'IMAGE(x))
end;


texts:
I'm looking for some insight into how something like multisim actually works. If I understand correctly it has spice under the hood but how does it actually analyze the circuits?

Is there some numerical method it's using or is it performing nodal/mesh analysis on the circuit at run time?

Any info would be great at this point, I just need somewhere to start looking for how it actually works under the hood.


texts:
In the datasheet of the dsPIC33FJ128GP802 it is said that the SNR of the 16 bit audio DAC module is 61 dB. What does this mean? How much RMS white noise voltage should I hope to see?

I know the SNR is the ratio of the "signal I want" and the noise. Which signal is used as "the signal I want" when the manufacturer specifies that 61 dB value? Is it a sinusoidal signal of maximum peak-to-peak voltage?


texts: transformer - can it also be connected to 24v ac

texts: if the a transformer can lower the voltage from 230 to 12v ac @ certain amount of current, given the same transformer can you give it say 24vac and still get a proportional output on the secondary?


texts:
I built a 5x8 LED array using 10mm white (3.3v) LED and 270 ohm 1/2W resistors and a 24v input power (24v 1A AC/DC adapter non-transformer).
Now resistors are very hot (Thermometer shows 56ºc).
How can I fix this? Does changing resistors with 1W versions solve it?
Here is the schematic:

Thanks


texts: Make 'smart' USB Dedicated Charging Port

texts:
I would like to create a circuit that is able to charge any USB connected device from my 5V rail with 1A current limit. There are many different USB devices, asking different kinds of currents, so:

1) I planned doing it with a dedicated chip, that handles all the enumarations and sets current limits that I can provide.

BUT I feel it's an overkill, as I want to set my current limit to 1A (So any device could get only 1A max). And this probably asks a lot of firmware.
This is the schematic I initially planned to use:

2) Then there are wall-chargers which seems to power anything quite nicely wihout any 'smartness' - also acting as DCP.

Question was - Couldn't I just short the D+ D- pins, basically act as a dedicated charging port ? Without the chip?
Because as I've read, devices set their modes very differently on D+/- pins so there's no One way of defining it. Which was assured to be true. Probably any device I plug in with USB cable, might ask more than I can supply (since it's acting like a wall adapter) and could destroy my board.

SOLUTION_1:
So Shorting D+/- is an option (not 100% universal). This is also visible on some of the teardowned AC/DC USB wall adapters seen here. Some have resistor dividers, some seem to have other magic going on (depening on manuf. I guess).
All cheap 'travel' adapters seem to have D+/- shorted.

The drawback is that I have to physically limit the current if any device wants to get >1A and that can be troublesome on the design side (heating of protection components, added current consumption, possible physical faults which renders the port useless).

SOLUTION_2
Suggested also here in the answers, was to use a dedicated DCP chip (such as TPS2514x) which can communicate my 1A current limit and act as a DCP (I would still have a resettable fuse on the VUSB line though). See also here

That way I think, I get more control over the current I allow the device to take. (a bit more expensive, but much safer).

Thanks for the info, I believe I've reached my verdict for using solution 2 in my case (wouldn't want to destroy any phones or my own board).


texts: using a 9 volt AC 25 va power supply in lieu of a 9 volt AC 2000 milliamp power supply

texts: I have a Line 6 Pod 2 modeling box that needs a 9 volt AC 2000 milliamp power supply. All I can find is a 9 volt AC 25 voltage amp power supply can I use that instead?


texts: How to implement a current controlled voltage source, or a comparator that trips once a certain current is reached?

texts: I have current flowing through a CCVS, once 10A is reached, the CCVS puts out 10V, which takes a comparator's output high. The current that goes through the CCVS continuous to the load. Is there a way to implement this without an ideal CCVS?


texts:
Our team is planning to make a HAB (High Altitude Ballon) project for our university. We are planning to use XBee pro 868 RF modules (we are in Europe so we can not use 900 MHz band). We have to communicate to the base station from the payload from 20-30 km distance. My question is, what kind of antennas will we need to use? The Xbee data-sheet says that with high gain antennas the module can communicate up to 40 km with clear LOS (line of sight). If we put high gain antennas like YAGI types on the base station, do we still need to attach high gain antennas or are dipole antennas enough for the payload ?

Note : I know that at some distance the connection will be lost and we have to move our base station according to last GPS data to find payload location landing area. But we are trying to do best as we can to extend communication duration before we lose the connection.

Module specifications:


texts: Is analog SPDT IC switch same as mechanical relay?

texts:
I am working on a project which require to trigger a SPDT switch using a button to pass a small signal voltage across (~3.3V).

reference circuit image below

The requirement is:

signal must still pass through (pass through NC) even when relay/switch power is
off (like what a normal mechanical relay would react)

Due to the small voltage, try to make it small & saving cost, I wish to avoid using mechanical relay. I found a SPDT analog switch TS5A3157 by Texas Instruments

My question is, will this IC work & pass signal to NC node when VDD is 0V (battery died). Or is there any alternative solution to do this?


texts: Low weight split core transformer on 11kVA transmission line

texts:
I've seen transmission line energy harvester's that utilise a split core transformer. Here is an example.

However, I fail to see how this is possible when a transformer cores which are small enough in size and weight go up to around 1kVa.

If I am correct an 11kV overhead transmissions line carries a current of around 100A. This gives a power rating needed for the  transformer to be at least 1100kVA. This well exceeds the limit.

Is my logic correct or am I missing something in this equation?


texts:
I am designing a PSU capable of producing 5 watts @ 5V 1A. The design will power about 12 RGB LEDs (totaling about 400mA @ 5V) and a audio class D 1.4 W amp. Space is no issue but efficiency and cost at low quantities is!

Note: I built a flyback design where space and size were a huge issue and the transformer worked about to be a very difficult problem to surpass. I ended up going with a $16 transformer... So this time around I started with a different approach after looking at transformers that are 9$ and take 120VAC to 10VAC @ 1.3A... So here where I started:

A plain and simple design

Vout into a linear regulator and done... only the efficiency will be horrible burning between 1 to 3.3 watts in heat

Vout into a DC-DC buck converter? My thoughts are that if Vout stays well above the minimum voltage of the buck then it should function even with the large ripples.

Questions:

I have read a lot that flyback is the way to go in my situation but the difference between a $16 and $9 for a transformer at a qty. of 1 is huge to me. Most of the flyback designs call for a custom transformer and this is just not feasible to me. I know I am not in the norm as I plan to build between 10 to 100 of these but, am I justified in my thinking or just ill informed on this design process?
Is it ok/safe to feed the Vout ranging from 7V to 13.5V @ 120Hz into the buck converter?

Vout while drawing a mean of 1A


texts:
I am completely new to the electronics game, so please excuse any layman's terms.

I'm trying to repair an LG IPS234V monitor that has recently started glitching. Once any video input is attached, but only after about 30-60s, the screen will flash up bright lines every 3s.

I've replaced faulty capacitors in a plasma TV and older LCD screen and guessed it might be the same thing, so I opened up the monitor and can hear similar clicking noises to those previous cases.

The only thing is, the part of the board where I can hear the clicking has none of the bigger electrolytic capacitors I'm familiar with.

There is a disc shaped component, labelled with an overlined 100, that has a small hole in it's side and looks as though it may have leaked - is this just a smaller version of the electrolytic capacitors? If not, what type of component is it?

Everywhere I've read has said to use a ESR meter to test a capacitor in board, but is there any way to test it with a bog standard multimeter?


texts: Does MPLAB X have a call-graph analysis tool?

texts:
I'd like to start understanding how deep my microcontroller's stack goes (even if it's only an estimation).

How can I do this using MPLAB X?


texts: How to protect electronics from static electricity during shipping

texts:
I have some electronics (EDIT: electronics are in enclosures, but with lots of wires coming out of the enclosures; the electronics are a part of a prototype) with ESD sensitive components I need to ship overseas (air freight). I'm using pick-foam (soft black foam) to create a form-fitting mold for the electronics. The shipping container is made from polypropylene. When I press the pick-foam into the polypropylene container, I can feel static building up. That means that jostling during the flight will generate static between the foam and the container.
Also, before the electronics are put into the pick-foam, they will be put into silvery ESD bags.
My questions are:

Will putting the electronics in ESD bags be enough protection from static or static discharges?
Is there something I can do to the shipping container to reduce static build-up? For example, can I coat the inside of the container with something?

2a. (EDIT: I just learned they make pink anti-static pick-foam. I can switch to this, but is it worth the switch if my electronics are already in ESD bags?)

If a customs official opens the ESD bags, how much static damage could they cause? Do you have a suggestion on reducing damage if they open the ESD bags?


texts:
This is a board out of a Super Nintendo game cartridge. It appears to have damage from a few of the leads, and this game definitely doesn't work when tested. The game is very rare and worth my time and extra $$ to fix. Is there a way to fix these pin issues?

Thx Stack community!
-Dave


texts: What happens if we reverse the configuration of diode in window comparator? Will it remain a window comparator?


texts:
I am interested in using one of these cheap stepper motors for one of my projects, but need a step angle of ~2°. I came across the 28BYJ-48 and noticed that it has a "stride angle" of 5.625°/64. What exactly does this mean? I doubt it will give me the 2° accuracy which I desire, so maybe I could use a gear system to reduce that step angle further.

But in general, what is that stride angle referring to?


texts:
I am trying to detect line voltage (230V AC, if the supply is ON/OFF) by a microcontroller with the help of an AC optocoupler. The optocouplers I have evaluated are PC814, H11AA1 and SFH620A-3, out of which I found SFH620A-3 to be more efficient (must be due to the better CTR). I had connected a series resistance of 440K (1/4W) and everything seems to be fine i.e the microcontroller is able to sense when there is line and otherwise. While testing my circuit at various input voltages I found that the opto will start giving fluctuating output when my voltage is 145V. I calculated the voltage and found that for 145V AC and a series resistance of 440K, the current is just 0.33mA which may to be insufficient to turn on the opto. Now I could reduce the resistance, however the heat dissipated would be more (which I don't want). I am also not able to use a x-capacitor or use a transformer due to size constraints. Due to all these factors, someone suggested me to find another opto which works at very low current. Hence I started searching for it and found  one i.e SFH628A-3, however I am not good in understanding their datasheet and need help to see if it fits.

Sorry for the long story, I am still learning.


texts: How can I see if this circuit would work on a breadboard?

texts: I have drawn a circuit but I am not sure how I can make it work if I will have to build it on a breadboard. Is there any breadboard simulator type of thing?


texts:
I picked up something called a quartz antenna at a surplus store for $2.75 so I could tear it apart. This is what I found:

There were two small cardboard boxes filled with loose quartz crystals inside, with no electrical connection to anything. There was a small screw at one end of the device, presumably to connect it to an antenna. I've taken E-Mag, and the only thing I can possibly think of that this does is change the permeability or permittivity of the space around the metal thing inside. Is this device basically "healing crystals" for RF or is there some principal it's using that I don't know about?


texts:
So I'm building a life-sized battle damaged terminator with a 3.7v 240 mA spy cam in the human eye, and a red 1.8V LED in the exoskeleton exposed eye. When the camera is powered by a 3.7V 340 mA power supply, I want the LED to also be powered but want to make sure I don't overheat or under-power anything. I'm guessing at a parallel(?) circuit like the below:

Am I on the right path here or do I also need to up the power supply to account for the 1.8V LED? I understand I only need a 95 ohm resistor but all I have are 100, 220, 330+.

Update: So I found the actual LED Datasheet:

Does this mean the LED is actually 2 Vf and 20 mA?

This is my first project and only have worked on basic automotive electronics so my apologies for my ignorance in advance and thank you for taking the time!

UPDATE:
So, turns out the "3.7V" power supplies were actually reading 8V+, so I swapped them out for a standard 5V .5A USB Charging brick, which worked on the camera alone before. Trouble is, with the LED, the Camera would not work, so I tried a 5V 1.0A charger, same problem. So I tried a 5V 2.1A charger and it worked! Trouble is, now the camera overheats. (registering over 40C). So with the revised diagram below, can anyone tell me how I should be able to safely power the camera and LED without overheating the camera while using a basic USB charger?


texts:
I have a doubt about how to connect the following device (a RF power meter, AD8318) to the external circuitry. Let's consider the device:

There is the input RF coaxial cable, the power supply terminals (VCC and GND) and the output port. Regarding this last one, you may see that there are two terminals: the square terminal (which is GND) and the circular terminal (which is the signal output pin).
I have built the following stage of this circuit and I have connected its input pins between the circular terminal and GND of power supply terminals.
So my question is: is the GND of power supply the same GND of output port? Obviously they are short - circuited (so a multimeter will see a short circuit), so at low frequencies I would use them indifferently. But since this device works quite high input frequencies (1 - 8000 MHz), I was asking if there may be some problems, since at those frequencies also a little short circuit behaves like a transmission line.
So, can I avoid to use the square output terminal and take the output signal between GND of power supply terminals and the circular output terminal?


texts:
Assume a 2-bit midrise quantizer with (voltage,codeword) pairs (-3,0),(-1,1),(1,2),(3,3) where step size delta is clearly 2V. Now, calculating PSQNR using the intervals, we have 20log_10(V_peak/qnoise_peak) so Vmax = 3V or 1.5delta.  Of course quantization peak error is delta/2 so I should have 1.5delta/(delta/2)=3 in the log.

Here's the problem: textbooks and almost every tutorial I saw take 2^qbits=2^2=4 inside the log function.  I feel like the number of levels(4) gets confused with the number of intervals(3).  I'm pretty sure I'm the mistaken one, can you explain me how?


texts: Proof of the superposition theorem in linear circuit analysis

texts:
I couldn't find a proof of the superposition theorem from circuit analysis anywhere online. I thought it might be helpful to ask and provide my proposed proof as an answer to gather feedback and improvements.
The superposition theorem I am referring to is the one that says if you only have "linear circuit elements", then the solution to the overall circuit, in the case of DC circuits at least, is the sum of solutions you obtain to variant circuits where only one source is left on (voltage sources become short circuits while current sources become open circuits).


texts: I know you can smooth DC with a capacitor but what if you have an unstable mains AC voltage (here in the UK that's 240V 50Hz)? Are there components that can be used or products one can make/buy for the same sort of end goal, a more constant supply?


texts: Digital Architecture Design Question: Fast way to perform a floating point exponential operation

texts:
does anyone knows how is the fast way to perform a floating point exponential operation? (like this y = 2.71^(3.45))
Thank you to all posible links to references or articles.

EDIT:

I am pondering several possibilities:

Doing by System Generator (I am using the 9.2.01 version)

Using some Free Xilinx IP

Using some open libraries like:

VHDL.org
OptNgn

Using an open-source ALU


texts:
I would like to buy this IP68 plastic enclossure below for my electronic project:
https://www.chinaenclosure.com/products/102-70-52mm-ip68-waterproof-plastic-enclosures-for-electronics-from-china-manufacturer-AK10514.html

Inside this enclossure, i plan to put an RF antenna connected with my PCB.

I would like to know if my  antenna gain would not be affected, even when the antenna where be inside this enclossure, and if i will still have a good RF 433mhz signal

Thanks a lot.. ( and sorry for my poor english)


texts: What is the correct way to bias a floating instrumentation amplifier?

texts:
Im designing a voltage measurement circuit that needs to measure differential signals in the order of mV in the presence of high voltage common mode noise.
Im using a isolated DC/DC converter that is connected to mains earth by a 1nF capacitor. Im planning to measure the differential voltage with an instrumentation amplifier and an ADC.
I only have a unipolar 3.3V supply to power the amplifier and Im aware that I have to bias the inputs to a suitable common mode voltage.
I have tried the following circuit but the voltage in VDIF+ and VIDF- with respect to my floating ground is to high for the differential amplifier. Reducing R1 and R2 is not an option because I need a high impedance input
What is the correct way to bias the instrumentation amplifier?


texts:
I am using the MCP601 for rectification of small AC signals. I got it working.

simulate this circuit – Schematic created using CircuitLab

however at high frequencies (20kHz) weird behavior starts to surface such as this.

I understand is has something to do with the chip spending too long in saturation and can't catch up. I also heard that you can get a faster OP AMP in terms of slew rate and it would fix the problem as well.

But shouldn't this OP AMP Already be suitable as the Slew rate equation is \$2*\pi*F\$

if we do the math

\$SR = 2*\pi * 20kHz\$

\$SR = 0.1256V/uS\$ the op amp is stated for 2.3V/uS ?

Can anyone explain to me why is this is happening with this op amp? and why isnt the current slew rate satisfactory enough for this current application.


texts: 555 timer to control a servo with 2 variable positions

texts:
If possible, I'd like a circuit with a 555 timer, 2 potentiometers and I want to control the circuit with 1 digital input (5V / 0V).
With the 2 potentiometers, I want to fine tune two fixed positions. With a digital input line (coming from an CMOS NAND gate) I want to steer the motor to one of these two positions.
Is such a circuit even possible with a 555 timer?
And if so, how would it look like?
__________________________________
Background:
I know that a uController is cheaper and better.
I can program attiny chips, but the people for who I am developing for cannot.
They can solder a circuit, and that's it. That is why I am also "researching" an analog solution.


texts:
What is the meaning of Input Hysteresis in the context of a RS485 transceiver?

Thanks


texts:
I am having troubles understanding how the following circuit works. It is from the AoE book 3rd ed. p. 196 Fig. 3.99C.

I added the resistor in red myself as I assume it was missing from the schematic (maybe I am wrong).
Here what authors tell about the circuit.

This circuit is a bit tricky, because you have to juggle several time
constants appropriately*. But the basic concept is simple, and
elegant: charge a capacitor from the inverted output of the
flip-flop’s control input, then momentarily connect the charged
capacitor to the control input to make it toggle.

*The capacitor’s charging time to the new state τC=R1C1 should be ∼100 ms to allow for
switch bounce; R3C1 should be much shorter, and the discharge time
constant of output transistor’s gate capacitance (R3 +R4)Cg should be
faster still. Here we chose 100 ms, 2 ms, and ∼0.4ms, respectively.

Could anyone please explain in step-by-step manner, starting from the OFF state, then 1st button press, then 2nd and return into OFF state again? (With all the voltages and names of the components).
Thanks in advance.


texts: Coded OFDM, interleaving, sensitivity, and narrow band interference

texts:
Coding (which is a controlled redundancy) and interleaving across sub-carriers protects OFDM signals from a narrow band interferer (CW) that could destroy one subcarrrier. It provides a kind of frequency diversity

Suppose we have an AWGN channel , a coded OFDM signal with a  certain modulation and coding scheme at a low coding rate and a certain corresponding sensitivity.

Suppose now that this signal is hit with a strong inband CW destroying one subcarrier, would the protection provided by coding and interleaving allow reception of this signal at the same sensitivity level when it was exposed to AWGN only?


texts: Wide Voltage Automotive Status To Microcontroller Input

texts:
I need to monitor the status of a wire in an automotive application that can have 10-40VDC on it at any time. What is a good approach to limit the voltage to a microcontroller input across such a wide range? I plan to use a 10nF cap and TVS for ESD and other transients but I'm not sure the best approach to limit the expected voltage. If I can reliably detect 10V, 40V may burn up the input resistors (or resistor and zener?) or I can limit for 40V and not sense 10V.

The signal is a simple on off status line that I'm tapping into. It won't be carrying any data or change state very often. I will be sampling it occasionally in the micro to determine if it's high (1V to 40V) or low (GND to under 1V).

Thanks.

Edited to add that my microcontroller will be running at 3.3V and a logic low needs to be under 1V. Any solution I use must include a low value cap between the input and GND and either diode clamps to Vdd and GND or a Transil.


texts:
Specifically, an STM32F051 has some limitations on pins also used for the 32 kHz "LSE":

  PC13, PC14 and PC15 are supplied through the power switch. Since the switch only sinks a limited amount of current  (3 mA), the use of
  GPIOs PC13 to PC15 in output mode is limited:

  The speed should not exceed 2 MHz with a maximum load of 30 pF.
  These GPIOs must not be used as current sources (e.g. to drive an LED).

  After the first RTC domain power-up, PC13, PC14 and PC15 operate as GPIOs. Their function then depends on the content of the RTC
  registers which are not reset by the main reset. For details on how to
  manage these GPIOs, refer to the RTC domain and RTC register
  descriptions in the reference manual.

This seems to mean that these pins can only sink a combined 3 mA, so they must be configured as open drain only, not as push-pull?

The reference manual says

  When PC13 is not used as RTC alternate function, it can be forced in
  output push-pull mode by setting the PC13MODE bit in the RTC_TAFCR.
  The output data value is then given by the PC13VALUE bit. In this
  case, PC13 output push-pull state and data are preserved in Standby
  mode. The output mechanism follows the priority order shown in Table
  80. When PC14 and PC15 are not used as LSE oscillator, they can be forced in output push-pull mode by setting the PC14MODE and PC15MODE
  bits in the RTC_TAFCR register respectively. The output data values
  are then given by PC14VALUE and PC15VALUE. In this case, the PC14 and
  PC15 output push-pull states and data values are preserved in Standby
  mode. The output mechanism follows the priority order shown in Table
  81 and Table 82.

The tables then show that with the respective bits set to zero the pin is a "Standard GPIO".

RTC_TAFCR then probably should be reset manually (before?) trying to configure it as GPIO output?

What are the implications for using it as an output, e.g. with an external mosfet - does this then have to be a p-channel with a pull-up resistor on its gate? As an input it could be used regularly, except that it's not five-volt tolerant?


texts:
I am new to field of charger designing but I have to complete one project of battery charger for 48 V 20 Ah Lithium-ion battery having 5 A max charging current.

The previous person had done work of designing PFC boost converter which is giving 400 VDC now I have to design the next circuitry but i do not know even fundamentals of charging like cc, cv charging modes and how to obtain them, how internal resistance plays role in current designing. So which books or links I should refer to start the research.


texts: What is equivalent Resistor different Resistors put them in series or in parallel if they have a different wattage and different resistance?

texts:
What is equivalent Resistor of two this different Resistor put them in series or in parallel if they have a different wattage and different resistance?
In practice somtimes we have a resistor with  \$\frac{1}{4}\$watt ,  \$\frac{1}{2}\$watt,  \$1\$watt or etc...
But let`s say that wattage of resistor is  \$\frac{3}{4}\$watt or \$\frac{3}{5}\$watt, or etc...

So what is the equivalent Resistor of two this "\$w_1\$ watt \$r_1\$ resistance" and "\$w_2\$ watt \$r_2\$ resistance" resistor put them in series or in parallel?

We know that if they have the same wattage \$w\$ watt and \$r_1\$, \$r_2\$ resistance then the equivalent Resistor might be:

1) in Series \$w\$ watt \$r_1\$ + \$r_2\$ resistance
2) in parallel \$2w\$ watt \$\frac{1}{r_1}\$ + \$\frac{1}{r_2}\$  resistance

But what about my question?


texts: Tesla spark gap causing touch lamps to turn on

texts: I have a mini DIY Mini Tesla Coil Kit 15W Mini Music Tesla Coil Plasma Speaker and have noticed when I play various "complex" signals using it, it causes my capacitive touch lighting on the entertainment system in the living room to turn on (which is about 30 feet away).  Is there anyway to prevent this or at least figure out the correct signal to turn it off if my coil turns it on.  I did do a search but all I found was short explanations not how to figure out the correct signals that will turn it on or off. http://www.arrl.org/touch-lamp


texts: Positive and negative feedback in opamp in same circuit

texts:
In our class we encountered several opamp circuits, for example, Non-inverting integrator:

simulate this circuit – Schematic created using CircuitLab

or we can consider the sallen-key type high pass filter:

simulate this circuit

Question: In such circuits, are these considered as positive feedback or negative feedback, that is, can we say the input terminals of opamp can be virtual grounded or not?

Question: Also what is the use of this kind of positive feedback?

My intuition is that it depends on capacitor time constant, for large time constant the negative feedback will dominate. But for small time constant, the capacitor will get quickly charged and discharged, so positive feedback will dominate.


texts: Smart ways to detect a button (less power consuming)

texts:
During a meeting for a particular project I was asked to think about the way to detect a push on a button with a MCU. The detection should consume as little power as possible. At the first glance, I thought the typical circuit with a pull-up or a pull-down :

simulate this circuit – Schematic created using CircuitLab

I don't account for some anti-bounce features here, as that is beyond this question's scope. In either case, when the button is pushed, the total current value that flows depends on the resistor value. To minimize it (the current), I could increase the resistor value but not so much since, if I am right, it also depends on the input pin leakage value. Plus, a large resistor would recover slowly.

My question is the following one : what are the smart ways to detect a button pressed that doesn't consume power (typically for a high power consuming application)? Are there any methods that are barely power-consuming when the button is pressed?


texts:
I want to connect a RFID-RC522 with pic16F628A microcontroller. The only tutorials I could find are those that have RFID-RC522 connected with arduino. The reason why I want to use RFID-RC522, is because I already had it laying around my house, for arduino projects.
The only thing I want it to do is to make it turn on a LED the first time the tag is scanned and turn it of the second time the tag is scanned. Can someone give me a link or instruction on how to do this. Thanks in advance.


texts: Troubleshooting an ATMega328p clock setting

texts:
I am trying to run my ATMega at 16MHz using this crystal

I set the lfuse bit to F7 (see here)

The command I used to set the lfuse bit was

C:\>avrdude -p m328p -P lpt1 -c stk200 -U lfuse:w:0xf7:m

avrdude: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.02s

avrdude: Device signature = 0x1e950f
avrdude: reading input file "0xf7"
avrdude: writing lfuse (1 bytes):

Writing | ################################################## | 100% 0.00s

avrdude: 1 bytes of lfuse written
avrdude: verifying lfuse memory against 0xf7:
avrdude: load data lfuse data from input file 0xf7:
avrdude: input file 0xf7 contains 1 bytes
avrdude: reading on-chip lfuse data:

Reading | ################################################## | 100% 0.00s

avrdude: verifying ...
avrdude: 1 bytes of lfuse verified

avrdude: safemode: Fuses OK

avrdude done.  Thank you.

I had code on the chip that was blinking a LED once every second.  After I set the lfuse bit it stopped.

I tried to read the lfuse bit via

C:\Documents and Settings\admin>avrdude -p m328p -P lpt1 -c stk200 -U lfuse:r:-:
h -U hfuse:r:-:h

avrdude: AVR device not responding
avrdude: initialization failed, rc=-1
         Double check connections and try again, or use -F to override
         this check.

avrdude done.  Thank you.

I believe I have the crystal setup correctly on pins 9 (TOSC1) & 10 (TOSC2).  I am using 22 pF caps.

I am seeing 5V on pin 10 and 0V on pin 9

What steps can I take to troubleshoot this?


texts:
I worked with a digital oscilloscope which could automatically save data on a pendrive, but when I checked the data, I found it in different form. In excel sheet are given two things named "timebase" and "voltbase". I think I need to use these two things to convert data to correct form. Can anyone help me how should I use these two things?

I used following oscilloscope:


texts:
This is probably the best article for a beginner about impedance with respect to headphones.

I haven't managed to find an explanation of why the impedance of headphones is just a single, real number (like 250 Ohm). I thought impedance is a complex number, so it should have real (resistance) and imaginary (reactance) part. Maybe the imaginary part is just zero. All I know is that impedance varies with frequency.


texts:
I have a SIM card reader connected to an ARM, and I'm trying to get the SIM to send an Answer To Reset (ATR) and to get the reader to capture it.

As I understand, an ATR is sent after an "electrical reset" by the card to the reader. Now in my design, VDD to connected to 3.3V so I cannot use that pin to make the electrical reset. The only other pin I see can that be used for that purpose is the STOP pin. However, the datasheet specifies that the STOP was not designed for the electrical reset:

  With the STOP pin a low current shutdown mode can be activated making
  the battery life longer

How should I make an electrical reset to the pin to get an ATR?


texts: Colpitts Osc. in ngspice: type of analysis and "singular matrix"?

texts:
I'm new to simulating circuits in spice (in this case, in the ngspice implementation in KiCad's nightly builds) and trying to build a simple Colpitts oscillator:

I'd simply like to "power" the thing using V1 and get a plot over time of the voltage at Vout -- seems like this should be pretty simple, but I can't seem to get it to work.

First of all, what type of analysis should I use? I had assumed an AC analysis but maybe I'm wrong. I've been using 1,000,000 points between 750Hz and 1250Hz (the given cap and inductor values should produce a frequency of 1MHz.) Trying to probe Vout, the simulator tells me "Error: vector frequency not found!"

Second, no matter the analysis I run I get a message, "Warning: singular matrix:  check nodes net-_c2-pad2_ and net-_c2-pad2_". As far as I can tell C2 is connected correctly and it certainly isn't connected to itself. I suspect this is some quirk of how spice reports errors but searching the web has got me nowhere.

Can someone provide a hint?


texts: How to reduce voltage without using Transformer?

texts:
Is there any way to reduce voltage without using transformer? I have a supply of 24 volts AC @ 1500mA (1.5A) and I want to convert it into 6 volts @ 500mA. Because I have to supply the 6 volts to the 7" compact LCD screen via rectifier. Since, there is no enough space available in the LCD housing to use transformer and I think transformer may also cause screen to damage due to its magnetic fields.

Schematic will be highly appreciated.


texts: Voltage drop when measuring battery capacity

texts:
I'm trying to build a battery capacity tester for Li-ion batteries.
I made this schematic using Arduino:

While bush button is not triggered arduino only shows battery voltage on Serial & when button is triggered it turns on the MOSFET and starts the test.
My problem is while MOSFET is off the battery voltage that arduino reads is battery's 100% voltage (e.g. 3.97v)
But when MOSFET turns on the battery voltage drops to a lower value (e.g. 3.21v for that initial 3.97v) !
And when the test is finished (arduino reads 2.7v) and it turns off the MOSFET that dropped voltage comes back! and 2.7v becomes 3.5 !!
for different amount of load resistor this drop is different (larger resistor ,less drop!)

Why this happens? am I doing something wrong?


texts: How can I size the current ripple of a DC-DC converter for lithium batteries

texts: I am designing a bidirectional DC-DC converter to charge and discharge batteries on a DC bus. The power of this converter is 50 kW and the average current in the inductor (the same as that on the battery) is 125 A. By designing the converter for a 20% current ripple I will have iL_min = 112.5 A and iL_max = 137.5 A. The frequency switch is 25kH. I wonder if this ripple of 25 A current is harmful to the battery bank.


texts: Any improvements you can suggest, to these two 555 circuits?

texts:
This is a continuation of my original question that got put on hold...
Any IC, to control a LED with a single push-button (ON,OFF,FLASH)

I have come up with two solutions that work for me:

a push button ON/OFF,
and a push button ON/OFF Blinker.

Can anyone suggest any improvement to these [two 555 circuits]

v2 here

Managed to remove the 555 for the ON/OFF functionality.


texts: N channel depletion FET vs P channel enhancement Operation

texts: As the title implies I am confused about the electrical characteristics of N channel depletion FETs vs P channel enhancement mode fets. Won't both of these devices act similarly as they both have negative threshold voltages? Thanks!


texts:
This is probably a dumb question but I'm not sure what voltage is on this specific node. Also ignore values, they are random.

Is it considered 0V or +V3?

Then would the voltage drop of R1 be V2 or V2 - V3?

Thanks!

EDIT: FULL PROBLEM
The op amp used in an inverting amplifier exhibits a finite input impedance Rin. Model the op amp shown in Fig.844 ... other questions.

This is the model given:

This is the model in the answer solutions they used:
also Vx = V1 - V2

My problem is understanding how they combined the inverting amplifier config with this model.  Can someone step through how they did this?

I assumed that when they combined a noninverting op amp model with the model given, the v- input would be grounded, however I was wrong I guess.  Other than that I think I figured it out.


texts:
I have a question about an circuit idea. I have one touch button (TTP223) to control switch on and off a Raspberry. Raspberry switchs on connecting one pin to gnd. How could i transform this on a hold on pulse to switch on it? I though about a IC 555 but i think is not the solution because is not a delay that I want but a hold on pulse (2 seconds, 3 seconds...).
EDIT 2: I want this: If I keep pressed the button 3 seconds, Switch on the raspberry (create that 0 signal (gnd)).
Thank you so much!


texts: How am I limited (or not limited) by using ATMega32u4 instead of ATMega328 with my Arduino? I want my sketch to perform a simple "echo" of a code it receives, does ATMega32u4 allow me to do this?


texts:
I have been trying to solve this problem for months now. I work as an Electrical Engineer in a tunnel project, we will use TBM machine to drill the underground station.

We have two tanks in TBM for grout purpose, which is Tank A and Tank B. Recently, we just realized that we actually have 2 tanks for component A (because we bought new machine from supplier, compared to the old machine that we used from previous project), making it altogether 3 tanks for grout.

The control system that we have in grout plant is to fill in the tanks if they got empty. Right now, the existing control only for one tank of comp A and comp B tank. The focus of the problem here is for comp A because it has two tanks now.

The tanks got level sensors each, for which the level sensor will send signal to PLC, and it will determine whether the valve for each tank should be opened or close. When the tank achieve both level sensor LOW and valve OPEN (I implement the AND logic here), the pump will run.

We do not intend to modify any coding in PLC since it was done by a subcontractor. What we can do is only mechanical modifications, where my boss gave an idea to use a simple relay. He asked me to crack down on how to implement it, maybe using 4 poles relay, but until now I still can't figure it out.

I was trying to implement the simple basic start and stop pushbutton circuit, where I try to manipulate the start and stop pushbutton by changing it to high and low signal from the level sensor, but the problem on how to connect them to PLC still cannot be solved, since we need to integrate two signals from two level sensors into one slot of PLC, and from one slot of output PLC to command either two valves to open.

How can I actually modify the control circuit of these two tanks?
enter image description here


texts: Strange problem with JY-MCU (HC-06) Bluetooth module

texts:
Short explanation: data sent over the bluetooth serial does not arrive correctly to the Arduino.

Yesterday I connected a JY-MCU bluetooth module to my Arduino UNO R3 to test it. I connected the TXD and RXD pins to Arduino pins 10 and 11 respectively and used SoftSerial to communicate. I first tried some AT commands that I found online. After AT returned OK, I ran the code found here and got this output:

Starting config
OK
OKlinvorV1.6

OK57600
Done!

So the name and pin changed failed, but I (supposedly) changed the baud rate successfully. However, any further attempt to run any AT command failed (no output), even when I set the new baud rate (57600) in the soft modem. I then tried to pair it with my PC and used the following code to test:

#include <SoftwareSerial.h>

SoftwareSerial mySerial(10, 11);

void setup() {
  Serial.begin(9600);
  mySerial.begin(57600);
  delay(1000);
}

void waitForResponse() {
    if (mySerial.available()) {
      while (mySerial.available()) {
        int a = mySerial.read();
        Serial.println(a);
      }
      Serial.write("\n");
    }
}

void loop() {
  waitForResponse();
  delay(2000);
}

In short, I wait for the module to receive something and then print the value of every byte. What's strange is that the data I send (using cutecom on the PC) is simply not correct - for example, sending the letter A (either lowercase or uppercase) outputs the number 161. However, sending two letters A outputs the numbers 161 and 176 despite the fact they are the same letter. I have very little experience with serial communication, but this looks like the baud rate is not correct. However, if this is the case, I don't know how to change the baud rate back to 9600 since I can no longer send AT commands to the module.

Any help on how to get the module to work properly or at least an explanation on what is happening here is more than appreciated.


texts:
I have 3 dummy strain gauges suffering no strain (all 120 ohms, G.F=2.1) and the fourth (same characteristics) is meant to pick up torque at 45 degrees on a rod. It has been verified on an external system that a reading can be obtained from this- around 300 microstrains are read on an external system with 3 120 ohm resistors. The circuit I have is mounted on an arduino (breadboard) and amplified by INA125P. Is there any reason that I would not be getting anything when i wire my previously described arrangement?
Here's a picture of the entire circuit, the makeshift wheatstone with resistors is to the top left of the breadboard.

Note that this wheatstone bridge is not giving any signal whatsoever regardless of gain (I've tried measuring with gain resistances varying from 10 to 1000 ohms in evenly spaced steps, nothing is read. This leads me to believe that the problem is in the wheatstone bridge and no other part of the circuit):

I further dissembled a full bridge and replaced one strain gauge with the one on the rod in the picture. This bridge worked on my circuit; but the strain gauge on the rod still shows no signal.


texts: Building a "Photo Booth" without the booth?

texts:
I am a web developer, and I've always liked the idea of creating PHYSICAL hardware things.

I have a hobby which is I take a picture of myself everyday, I've been doing it for about three years now. Recently the site I use shutdown, and I've been taking pictures on my local computer. I'm not crazy about sharing them with the world, It was just simple.

So I have an idea to help make my life easier.

My master plan would be to setup a small linux computer with a couple of peripherals and hang it on a wall, when I want to take a picture I press a button (like the staples easy button) and it snaps a shot and uploads it to the web.

Raspberry pi
Wifi Interface
Linux Compatible HD webcam
Button Interface
SD card storage

The system would need to be listening for the button press and run software (shell script) when its pressed. The following is a list of things the shell script would do.

delay the picture from being taken for ~3 seconds
take a picture and save it on SD card / local storage
run POST request to server somewhere
server saves picture

More elaborate and unnecessary yet cool features would be

sound camera click
flash

I guess my question to the community is, is this possible? Is raspberry pi right for this? I would like to ssh into it from my pc somehow rather then attaching a keyboard and screen. I'm looking for general feedback and comments. Point me in the right direction.

User @JYelton suggested I point out obstacles.

Linux Camera Driver Support
Getting the "Button" to connect and fire events
Hardware choice : Raspberry pi?
Something I may be overlooking?


texts:
I could swear that it was working for a while. I got back to my desk, tried it again, and it's no longer working. Could I have fried the NO pins on both sides? This is a DPDT relay. Everything works normally on the NC pins. I have never applied more than 5V. I do hear the relay click when I apply 5V to the coil. But when I measure voltage on the NO pins, I get 0V. Has anyone else seen this? I have two of these relays and I can't seem to get voltage on the NO pins with either relay. I should clarify that I'm expecting the same 5V power source to power both the coil and the common pins. If the NC pins work then I don't see why the NO pins shouldn't. In both cases the 5V is shared between the coil and any load attached to the NC/NO pins. I did try driving the entire circuit off a 9V power supply, but that did not change the results (and that does contradict my earlier statement that I've never applied more than 5V to this relay). My circuit is based on Charles Platt's "Make: Electronics", p. 59.

Here's the link to the relay product page.

http://www.omron.com/ecb/products/pry/111/g5v_2.html

Schematic I am trying to implement1


texts: I built a circuit which I strapped one electrode to the bottom of my shoe, and the other to my leg. This circuit consists of a high voltage DC supply in my pocket driven by a 555 timer. When it works, I am able to make static sparks to objects with a capacitance to ground and huge sparks from my finger to grounded objects. The issue is that I have to keep replacing the 555 timer because high voltage must be getting back into it. What is the best way to protect the timer from high voltage and is that likely the cause? The whole circuit is powered by 9vdc.


texts: What are the advantages of an ESC over a PWM?

texts:
I'm building an octocopter, and can't quite understand what an ESC (electronic speed controller) is used for. A brushless outrunner motor has three cables. Is there one common ground, one power supply (DC) and one cable to communicate with the ESC?

Does the ESC simply use the information gathered from the motor to decide when to turn the power on to get the maximum effect out of the motor? So the ESC is simply a PWM which synchronizes the pulses with the motor?

The ESC also has some extra features like turning down the power when the voltage is below a threshold, and using low resistance to brake the motor. If you don't need these features, is using a PWM just as good as an ESC?


texts: I'm currently trying to configure a device that I can connect via Bluetooth to my cell phone. I want the device Bluetooth range about  15 feet. How do I control a Bluetooth range?


texts:
I am using stm32f303k8t6 nucleo board and Keil V5 IDE.
I want to measure temperature with DS18S20 sensor over one wire interface.
I have downloaded the HAL library from https://github.com/nimaltd/ds18b20.

But how do i add these library to my project in Keil. Can some one help.

My project window looks like this

And the files inside the GitHub library looks like this.

Please tell let me know what is the proper way to add these files to my project.

I have added a group to my project->Sensor->add existing files->what next??

I have removed the .h files, text files and licences from the Sensor folder and followed what you have suggested.

I have done the same as above once again and it seems like added the c files to my project successfully.

But it couldn't find some other header file related to the library**(#include "gpio.h" , #include "cmsis_os.h")**. Is it the error in the library file or project setup error.?


texts:
I've recently bought a HC05 Bluetooth module, of which I hoped to use the general purpose input-output pins. The HC05 has loads of them, but I haven't found anywhere a single description on how to use them, except when in AT mode, which, as far as I understand (I may be wrong) can only be used when the device is not bluetooth paired (i.e. it's just wired to the PC).

So, if they can't be queried or changed remotely, what are they for? How else could I broadcast the value of a pin through bluetooth without a whole Arduino?


texts: Why is the AC coupling capacitor always 0.1uF or 0.01uF in high speed transceivers?

texts:
As I know, high speed transceivers always use a 0.1uF or 0.01uF capacitor for AC-coupling.

Tx--->capacity------------------->Rx
                |
                end resistor

Capacitor and end resistor are a high-pass filter.

If end resistor is 50 ohm.

I calculate bandwidth with
$$
f = \frac{1}{2 \pi R  C}
$$
if \$C = 0.1\mathrm{\mu F}\$, then \$f = 31.847\mathrm{k Hz}\$

if \$C = 0.01\mathrm{\mu F}\$, then \$f = 318.47\mathrm{k Hz}\$

But I always see 0.1uF and 0.01uF both used in the 1GHz, even 10GHz circuit.

As I calculated above, bandwidth should not enough.

I'm confused.


texts: How are induction motors designed to minimize cogging and crawling?

texts: Why does the induction motor performance phenomena known as "cogging" and "crawling" occur and how can motors can be designed to minimize them?