texts: Why do spectrum analyzers generate X-Rays

texts:
Most, if not all, old HP spectrum analyzers say

  X-Rays generated in this intsr are sufficiently screened

Why do they generate x-rays at all. The HP 8565E I am looking at can only measure up to 50 GHz so I have trouble seeing why it would have such high frequencies in it.


texts: Link budget - Path-Loss in a Wlan Network

texts:
I am struggeling with the dB calculation on an wlan-network. An antenna has dBi but the pathloss in the air is dB with the formula 100 + 20 * log(km). Can I just mix dB, dBi and dBm?

Here is a sample I calculated (where i haven't a solution):
This is a connection between two buildings with 10km space between them. This means 120dB loss according to the formula on top. The antenna has a gain of 18.5 dBi and a cable between the antenna and AP has a loss of 1.5 dB.

This means a loss of 103 dB. Is 103 dB the correct dimension?

The allowed EIRP in Switzerland is 20dBm. This means ouput of the AP is 20dBm - 18.5 dBi + 1.5 dB = 3 dBi or 2 mW.

The signal level at the receiver is thereof 20 dB - 120 dB = -100 dBm or 1 / 10^10 mW.

Is this correct or am I missing something important?


texts: How to use the DC in a DC offset AC signal?

texts: Many recreational vehicles have two sets of electrical wiring, one for AC power and one for DC power.  Is there a way to combine those lines so the AC has a DC offset and the DC appliances just use the DC?


texts: Shift an analog signal by a certain voltage, keep the amplitude

texts:
A sensor outputs a dc voltage varying between precisely 1.00 volt and a max of 1.10 volt. The receiver operates between 0.00 volt and 0.10 volt.

How can I level shift the 1.00 to 1.10 dc voltage to 0.00 to 0.10 volts?


texts: Inter die vs Intra die process variation

texts:
Due to fabrication process, there will be variations, among wafers as well as among dies across a wafer.
My question is that what variations are significant between dies? And what variations are significant between wafers?

Thanks very much!


texts:
A big request for clearing this simple doubt.
For an application, I am using antenna arrays(say dipoles and array length is 11 elements). Now, this antenna array will have the beamforming vectors based on the users distance and angle which I calculate using triangulation. I have a few questions on this.

1st question:

Now, that I know user's distance from the antenna, and I know I need to cast my beam onto the user who is at a distance d, I need to adjust my weights of the antenna. The steering angle I give the input from triangulation and get it and the beam rotates in angle. Now, I want to reduce the amplitude of the beam. Can the user distance in meters from the base station be considered directly for the amplitude of the beam ? If not, how can we convert the user distance to the amplitude required for the beam to just cover the user(user should always be in the tip of the beam)

2nd question:

I am also thinking on power saving. I assume that every antenna element will be fed with a current "I". I would like to know the equations(if they exist) for the changes in array weights for a specific user using beamforming, I should be able to get a relation with reduced current values. Because, If the user is close to the base station, I will have a lessen the gain and I will need lesser current for each element for supporting that gain. Is this theory right ?

3rd question:

suppose for a case, weight for one of the antenna array element is 1 and and for another element is 0.5
so is this relation true ? I (w=1) = 2 x I(w=0.5)

Please help me out !


texts: Why do we go for a Low side / High Side Switch ? Why do I find more of Low side switches than High Side in Automobile electronics ?


texts: Very high frequency out of SPI pin in ATmega16A

texts:
I was trying to interface ATmega16A with ENC28J60, and I was facing problems with it, so I decided to physically look at the signals b/w the master µC and the Ethernet chip using an oscilloscope. But to my surprise I am getting a very high freq wave out of the SCK pin which is around 15MHz.
Now here are some debugging I have tried.
No problem with USBasp programmer because the UART code is working perfectly.
No problem with the circuit connection as the UART is working and I am able to display any text on my laptop perfectly.
No problem with the clock fed as I've used both external crystal, internal clock and both give me the same error.
No problem with the µC as I have changed it many times and all of them behave in the same way.  I'll upload the code that i am using to initilize and transmit using SPI.

Please give me your suggestion and possible debugging tips. Thanks in advance.

here is my SPI initialization function.

 void SPI_initialize()
 {
   //configure MOSI, SCK and SSbar as output pin and MISO as input pin.
  DDRB  = (1<<4)|(1<<5)|(1<<7);
  //Prescaler: Fosc/128, Enable Interrupts, I have changed these values to Fosc/2,4,64
  SPCR = (1<<SPE)|(1<<MSTR)|(1<<SPR0)|(1<<SPR1);
  SPSR = (0<<SPI2X);
  }


texts:
I'm trying to simulate the following circuit

taken from http://www.techlib.com/electronics/battery_chargers.html.
The circuit is supposed to charge 6V battery (shown as Zener diode in the circuit). According to the author, this circuit can charge a battery with a higher voltage than what the cell generates. The solar cell is simulated with a 3V battery and a resistor. The circuit is here https://www.circuitlab.com/circuit/859v6932b322/solar-charger/
I can see that the transistors are on, but the zener diode does not turn on meaning that its voltage does not reach 6V.

Any idea why this is not working? Any suggestions for alternatives/changes?


texts: STM32: no interrupt handler getting called

texts:
I am having problems with interrupt handlers on an STM32L052C8T microcontroller. Every program that I try to run hangs forever after an interrupt is fired. This holds for SysTick interrupts, other timer interrupts (TIM2), and EXTI interrupts (EXTI6). I haven't tried other types of interrupt.
I suspect that the program is getting trapped in an infinite loop within some system code that is meant to pick the correct interrupt handler. Unfortunately, my debugger lets me access this system code only as assembly.
For simplicity, I attach a very basic program that hangs after a SysTick interrupt. The exact point where the program starts hanging depends on the value of the SysTick->LOAD register. Small values of this register cause the program to hang within HAL_Init() itself, higher values within SystemClock_Config() or even further.
#include "main.h"

void SystemClock_Config(void);

int main(void)
{
  HAL_Init();

  SystemClock_Config();

  int count;
  while (1)
  {
      HAL_Delay(3000);
      count++;
  }
}

void SystemClock_Config(void)
{
  RCC_OscInitTypeDef RCC_OscInitStruct = {0};
  RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};

  __HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE1);

  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_MSI;
  RCC_OscInitStruct.MSIState = RCC_MSI_ON;
  RCC_OscInitStruct.MSICalibrationValue = 0;
  RCC_OscInitStruct.MSIClockRange = RCC_MSIRANGE_5;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;
  if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
  {
    Error_Handler();
  }

  RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
                              |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
  RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_MSI;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;
  RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;

  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0) != HAL_OK)
  {
    Error_Handler();
  }
}

void Error_Handler(void)
{
  __disable_irq();
  while (1)
  {
  }
}

#ifdef  USE_FULL_ASSERT
void assert_failed(uint8_t *file, uint32_t line)
{
}
#endif /* USE_FULL_ASSERT */

I am using STM32CubeIDE with default settings for the compiler, linker, and debugger. These same settings worked perfectly (i.e., no hanging) on a different microcontroller, STM32L051K8T.


texts: Measuring 230V AC current with low sample rate

texts:
I have a resistive load of order of 1kOhm, on a 230V AC circuit. The load's resistance varies a little over time - the current draw may float between some 0.2 - 0.25A, slowly (order of minutes).

I have an ADC connected to 1-wire bus of an SBC. Single sampling takes time of order of 1-10ms  but for technical reasons I can only obtain a few samples per second ((and preferably even less; not nearly enough to trace extrema of the AC sine wave in software).

I need to find the current amperage of the load - not very precisely, just within some 10% precision. Simplicity of the circuit is preferred over speed or accuracy. I'd also prefer to keep at least rudimentary pretense of safety of the circuit.

How can I approach designing a circuit to get that measurement - something that will convert the AC current draw to some ~0-5V voltage levels for the ADC, and smoothed out enough to get values closer to RMS, and not random momentary points on the sine?


texts: Problem in blocking and non-blocking - verilog

texts: I have this code and I am having a problem in the product output, any ideas? I've tried a lot and it doesn't work.


texts: applying nodal inspection technique to supernodes with dependent sources

texts:
I was about to apply nodal analysis via inspection (to make it faster) to the above circuit, yet as we can see, it has a dependent source. So listing the equations for node(1 and 2) supernode a:

$$v_1(\frac{1}{2} + \frac{1}{6}) + v_2(\frac{1}{4}) -v_3(\frac{1}{6}) = 0$$

$$v_2(\frac{1}{4}) + v_3(\frac{1}{3} + \frac{1}{6}) - v_1(\frac{1}{6}) = 0$$

$$v_1-v_2 = 10V$$

Yet, it yields incorrect results (I tried solving it yet get wrong results). Are there any restrictions to nodal analysis by inspection when it has supernodes with dependent sources?

PS: correct answer are: \$v_1 = 3.043V\$, \$v_2 = -6.956V\$ and \$v_3= 0.6522V\$

Revision 2: instead of doing it the traditional way (like writing KCL equations), we can solve it via inspection. Are u familiar to it: The Inspection Method for Nodal Analysis and Nodal Analysis?  I'm trying to apply solution by inspection here but it doesnt work the way it should be (notice my equation above).


texts:
Despite some basic knowledge in electronics, and maybe because of my non-english tongue, I don't understand the term "fractional-order circuit", that I've read on a paper. Could a specialist explains the meaning of this term, as well as the applications of this field ?

That seems to be an emergent theme in EE (or resurgent) ?

Also Stability Analysis of Fractional-Order Circuits


texts: 3-terminal capacitors as bypass capacitor

texts:
The bypass capacitors are used  for example to filter out noise at the power supply of an IC. Usually 2 or more capacitors are applied in parallel to cover wider range of frequencies.

However, I have learned about 3-terminal capacitors that have extremely low ESL and therefore cover much wider range of frequencies than usual by pass caps. As I see it, instead of several bypass capacitors one cold use single 3-terminal capacitor. However, since I had never seen the 3-terminal capacitors in such role, I assume there are pitfalls that I am not aware of. What are they?

And what the 3-terminal caps are used for then?


texts: Using 555 timer with soil moisture sensor

texts:
I am using an IRROMETER sensor for soil moisture measurement. This sensor requires AC excitation, so I found an interfacing module for it from online. This is the circuit recommended by them:

The circuit was easy to simulate and these were the results:

Currently I am trying to understand the exact working of the circuit, since this is similar to the astable vibrator I am trying to relate them.

From the general circuit diagram, we can conclude that R1, R2 & C form the wave shaping network.

The following are my questions:

Which of the resistances form R1 & R2 in the case of my soil moisture interfacing circuit? Basically I need those values to theoretically calculate the duty cycle & ON time and then compare them with my LTspice simulation.
What exactly is the difference between the OUTPUT pin & DISCHARGE pin, since I am seeing the same waveforms from both pins?

Is the direct feedback mode same as the Astable mode? why is it called direct feedback?
Why is the OUTPUT pin called totem pole?
5.Why is the duty cycle different in my simulations and the one I have observed on the CRO, when I have used the exact same values of R & C components?
Also why is it said that the current through the circuit is of AC type when we are providing a DC supply?

The brief working of the circuit is given here by the manufacturers. Ignore the voltage regulator part and refer the circuit of the simulation. Till now I have figured out that the 390 Ω, 150 kΩ & 0.1 uF and the sensor resistance form the wave shaping network, but I am still not able to understand which ones are R1 or R2?

The same circuit I built in my lab, and observed it's waveforms on the CRO, sorry the pics are not very clear.
I am also adding the data sheet of this 555 timer module.
https://www.emesystems.com/smx/documents/SMX_2018.pdf


texts: TB6612FNG DC Motor Driver Low Current Problem

texts:
I have a TB6612FNG pololu DC motor Driver (datasheet), and pololu 488:1 6V DC motor (motorPage). It is clearly stated that motor has 2.9A stall current at 6V and driver has 1.2 continuous current and 3.2A peak current. When i properly connect my system via an Arduino Uno, with two DC motor, I observed that driver supplies only 0.8A when one motor is on stall, and the rpm of the other motor decreases significantly. At stall, voltage of the motors decreases significantly.

When I separate one of the motors and directly  supply 6V, it sinks 1.6A at stall.

The power cabling of the system is such that, 6V from power supply connected to breadboard so that Arduino and motor driver is fed from here. Grounds are common. Logic 5V supply of the driver is taken from Arduino 5V pin. Which becomes 4.5V when I measure on the driver. It is okay for the driver.

1- Why the driver does not supply the voltage as stated in datasheet.

2- Why the motor does not sink 2.9A at 6V stall.


texts: "Efficiency" of Switching Power Supplies and Theoretical Energy Loss

texts: I have heard that switching power supplies that convert, say, 110 VAC to 12 VDC, are very efficient. I understand that the power transistor that is regulating voltage is either on or off and spends very little time in its linear range, thus it doesn't burn much of the energy. Also I understand the principles of converting AC to DC via a full wave bridge. After the AC voltage is rectified, however, given that the voltage drops from up to 110VDC to 12VDC that energy (above 12) has to go somewhere. If the electrons coming from the AC are merely regulated down to 12 then I don't understand what happens to the lost energy. It has to go somewhere. In a very efficient system I would think that a small amount of current at high energy going into the AC input should produce low energy with higher current according to the equations. So I should be able to get by with a smaller gauge wire going to the input (at high voltage) of my switching power supply while having to use a heavier gauge wire for the output (at lower voltage). My problem is that I can't see how reducing the amount of energy on the same electrons can't result in some sort of heat generation. Where does the energy go? Can someone please explain?


texts: Help Identifying Component from guitar amp

texts:
I'm attempting to troubleshoot an old guitar amp and this component appears to be blown out.

Can someone here help me identify this component?


texts: Confusions with common mode voltage in a single ended system

texts:
I have extreme confusion in figuring out common mode voltage related topics.
I would like to illustrate my understanding first:
Below opamp has two inputs V+ and V- as usual. And lets say the differential voltage is:

Vd(t) = (V+) - (V-) = sin(w*t)

And lets say there is  DC common mode voltage.
When we measure the voltage between V+ input and the system GND(could be earth) the oscilloscope shows this difference signal as: (V+) + Vcm. When we measure the voltage between V- input and the system GND(could be earth) the oscilloscope shows this difference as: (V-) + Vcm. So the above circuit can be modelled as below??:

Is the above model only valid when the - input is not system or earth grounded?

Now imagine we have a single ended system with a floating signal source like a battery powered transducer. At the differential amplifier end the GND of the transducer is wired to the system ground as below(you see - input of the opamp is earth grounded here):

In this case when we measure the voltage between V+ input and the system GND(could be earth) the oscilloscope shows this difference signal as: (V+) + Vcm. When we measure the voltage between V- input and the system GND(could be earth) the oscilloscope shows this difference as: 0V since - input is wired to GND/earth. So can the above system can be modelled as in below?

And in a book I read the following about this configuration:

Here is a paragraph from the book for this configuration:

What does that mean here? Is common mode offset error higher in this configuration than in differential signalling. Im completely lost.


texts:
I am working on a medical device application and would like to use a solenoid with a variable turn density such that the force \$F\$ on a metal piston within the solenoid cylinder is not constant but is proportional to the the overlap length \$l\$ between the piston and cylinder - effectively functioning as a spring with spring constant as a function of the current.
$$
F(l)=k(I)l
$$
My naive assumption is that I can make this work by using a wire turn density which is a function of the overlap \$n(l)\$, instead of the usual uniform turn density \$n=N/L\$, where \$N\$ is the total number turns and \$L\$ is the total length of the solenoid.  I made some progress using the Ampere derivation of the magnetic field on infinitesimal slices of the cylinder but couldn't figure out how to do the line integral. Any insights would be much appreciated.


texts: Altium - Change Color of Error Text in HUD

texts:
I had this set up on my PC a few weeks ago but lost it when I had to switch computers. I am trying to remember how to change the color of the Online DRC Errors shown in the HUD when hovering over the segments causing the error. I do not want to change the color of any of the other text. For example:

I want to change the text color of the "Clearance Constraint" entries (or any other DRC errors) to red so that it's easier to pick them out as errors. I know there's a way to color-code the HUD but I can't seem to remember how. I'm using Altium Designer 15.1.


texts: why reduced resistance and increased current result in an increased amount of heat

texts:
Would a heating element have a very high resistance, or a very low resistance? (All comments in this post are based around the fact that the voltage is the same for each situation) I would have thought that a higher resistance would have resulted in more heat loss, but I've been taught that the higer the current, the more energy is lost to heat. Therefore, a lower resistance would release more heat.

Which one is right? Thanks for any help.

it is difficult to visualize the fact that reduced resistance and increased current generated more heat . If somebody try to explain me without much math because I know what


texts: IV relation changing load resistor of a solar cell

texts:
Consider the configuration in picture, where a solar cell is kept at fixed distance from  a light source and the load resistance is changed among different values.

simulate this circuit – Schematic created using CircuitLab

What mathematical relation is there between current and voltage while Rv is changed?

Since the solar cell is at constant distance from source I expect constant open circuit voltage of the cell \$V_{op}\$, therefore it should be

$$IV=P_{load}=\frac{V_{op}^2}{(R_v+R_i)^2} R_v\tag{1}$$

But also, at the same time,  $$I=\frac{V}{R_v}\tag{2}$$

So will the current-voltage curve be the intersection of these two curves?

I found on many sites that the current voltage characteristic of a cell is a curve like the one in picture.

Is the blue curve what I would find also in the situation I described? That is, are the blue curve points given by the intersections of \$(1)\$ and \$(2)\$ (for different values of \$R_v\$)?

Or is the blue curve in picture given by different mathematical relations? If so, what is this relation?


texts: Why are my copper PCB solder pads oxidizing?

texts:
I work at a place that sells LED strip lights and we don't have an engineering team, so I am hoping that someone can help me figure out what is going on because I've tried everything and I haven't been able to figure out what is happening through experimenting or asking my vendors.
I want to start carrying these IP65 solderless strip light connectors and have tested them with ten different kinds of IP65 silicone sheath LED strips.  My initial tests went great and the connectors were able to successfully bite through the silicone and make contact with the solder pads.  Everything conducted electricity perfectly fine and after running it through the IP testing it was able to help the strip maintain its IP65 rating.  Then a few weeks ago I was testing the connectors with a new strip light from a different company and I saw that all of my solder pads had turned a blackish-green color where they had made contact with the connector:

The picture above is the back of the strip.  The connector has these teeth that are not copper (and I'm not sure what type of metal they are because the vendor is being weird about it) and the teeth sink down through the silicone sheath and into the solder pads:

I tried running a few experiments and used the same strips that have a different type of silicone sheath and that one doesn't appear to be oxidizing yet (but it's only been a few days) and I've also tried doing some with the original problem silicone sheathed strip with and without silicone sealant.  It looks like when I use the silicone sealant in conjunction with the original silicone sheathed strip it starts to oxidize:

But unfortunately the connectors aren't able to seal properly without the use of a silicone sealant. My early tests with my original ten strips used strips that had an LSE 3M backer applied before they put it into the silicone sheath.  As soon as I saw the oxidation on the new strips I went back and cut open some of my original strips with the 3M inside that I had used the same silicone sealant on to see if the oxidation had perhaps just been hidden by the 3M backer, but when I cut a few open, they were completely fine:

I have asked the strip manufacturer and the connector manufacturer and no one seems to know why this could be happening.  I'm basically a pencil pusher who knows just enough about electrical stuff to be dangerous, so I'm not sure if this is a chemical reaction from the silicone sealant mixed with the sheathing on the strip or if the 3M on my first batch of tests somehow helped the strip's solder pads to not make contact with the bottom sheathing or what.  Does anyone out there have any ideas as to what could be going on? I super appreciate the assist!  Thank you!


texts: Why is it ok to use polarized caps to remove DC offset from an audio input?

texts:
I've seen circuit diagrams that use a polarize electrolytic to remove DC offsets from an input audio signal.

The cap is polarized. Why is this ok?


texts:
I'm trying to provide a 3.3V source for my micro controller from a 5V power supply, however seem to be having issues with all the 3.3V regulators I've tried.
I'm currently trying to use an MT1117-3.3, datasheet here.
When I turn on my 5V supply, the output I get from the regulator is 4.1V and 4.5V if I remove the load.
I tried an L78L, which gives a similar result althoguh apparently this requires 5.3V to regulate.
I've also tried an LM2931A which also gives a similar result although it's input voltage requirement is less than 5v.
Would appreciate any suggestions on what might be the problem. Diagram below.


texts: How to extend relay working time without controlling signal

texts:
I have following electric schema which works on 230V AC.

I am using remote controlled relay(RCR) to start and stop the engine. The problem is that I am not sure about wireless signal quality and I afraid that it may end in the situation that engine has started but not stopped.

Because of that I have safety switch which is time relay(TR). Circut works like this:

TR has NC connectors which are giving current to RCR even when it's turned OFF.
When RCR receives swiich signal it gives controlling signal to TR and powers the engine.
Engine is running and TR is counting time to change NC connector to open.
When TR reaches the time it switches NC connector to open.
When NC connector is open three things happens:

engine stops working
RCR is turned OFF
TR is turned OFF

And here it is a problem. When TR is turned off NC connector returns to the state closed. Because of that RCR is back online. But the time it happens is so short that it's not able to return to it's default state which is ON, so the system is back in point 2 instead of 1.

My question is how can I extend the time of TR open state? Naturally it will mean that I need some sort of "UPS" on TR controlling line, but I need something cheap that will last for 1-2 seconds(maybe even less).
Should I use some sort of capacitor?

I am kind of new in this field and some terminology may not be correct or some asumptions may be wrong.

UPDATE

I found some relay which holds a state without power for some time. I have no idea how it is called but it works like this:

When it receives signal it changes connector states and when the signal is gone it holds the state for given time.
I've changed my circuit a bit to work with this and it looks like this now:

And works like this:

TR is giving power to RCR
When RCR is switched on  it gives power to engine and hold state relay( HSR)
HSR is controlling TR control signal.
When HSR receives signal it switches TR counter
When countdown is finished RCR is turned off.
HSR is no longer recieving signal, but it still holds state for desired time.
RCR returns to default state.
HSR countdown finishes and it returns to default state.
Whole circuit is in starting state.

This solution is much cheaper than adding additional 4 relays.

UPDATE 2

I have an another idea, but I am not sure if it will work. My time relay is 12÷264 V AC/DC. I am considering using AC/DC 230/12V transformer and some capacitors for holding state. I have two capacitors 470uF 200V but I am not sure if they are big enough.
Using transformer and capacitors would not require additional delayed timer.


texts:
I have a solar charger which has a battery of 3.7V 8.14WH which is rechargeable. The battery was rechargeable but died. The charger wasn't working with the battery inside it, so I removed the battery and it worked directly from solar to charging device. Can I replace the 3.7V 8.14WH battery with a rechargeable 9V battery? If I can't, what should I do?

Thanks.


texts:
How do I go about finding/calculating the specifications of an accelerometer that can measure vibrations upto 2kHz and deflections upto 2mm?

EDIT: After calculating and obtaining 16000g's worth of acceleration, I consulted my mentor and it seems like we might not experience 2mm of deflections at 2kHz. However, now the problem becomes how to estimate what deflections we will see at that frequency if we use PL 140 actuators from PI and place them on the panel?

https://www.piceramic.com/en/products/piezoceramic-actuators/bender-actuators/pl112-pl140-picma-bender-103000/


texts: Please explain in detail how to take an S21 measurement for an antenna?  I know what it is... but how do I physically connect the antenna to the VNA to take the measurement?  Thank you in advance!


texts: I have a water detection circuit that uses 3/4's of a 4066 (SW1-3) as a 3-level sensor and the 4th to power the coil of a 12v relay which will provide power to a water pump if the water level is at least at the minimum level. The sensor works and powers 3 LED's to visually indicate water level. However, the switch to the relay powers the coil which then stays on even after the sensor is unshorted. And, while the coil is attached, the current apparently bleeds over to SW2 so that the LED attached to that switch also comes on. The connection to the relay coil is: GND > Pin 11, Pin 10 > relay coil, relay coil > +12V. Pin 12 is the trigger for the switch. My guess is that I need to do something to bleed off the coil when there is no current applied but I have no idea what needs to be done there. Any suggestions would be greatfully appreciated. Thanks


texts:
I am analyzing the integrator circuit and I can't get from which equation can I get the frequency where there is the intersection with x axis - 1/C*R1 ?

Thanks!

source


texts: How can I connect a 24v-powered inductive proximity sensor to a 3D printer control board?

texts:
I am attempting to connect an inductive proximity sensor to my 3D printer. The sensor I'm using is a Zhongde PL-08N2 sensor, which is an NPN output NC (Normally Closed) sensor. As I understand it, this sensor has an open collector output, and I am powering it with 24v. When powered up, the sensor's indicator light is normally on, and turns off when metal is placed near the sensor (which I believe indicates normal, correct operation).

The board I am connecting this sensor to is an SKR 1.3 controller board, which operates at 3.3v (though the digital inputs are 5v tolerant) and has a 10K pullup on the board for all the endstop connectors:

Of course, I cannot allow the 24v from the sensor to be applied to the input pin, so I used a reverse-biased diode as described at the bottom of this page:

This did not, however, work for me. The board shows that the sensor is always triggered, whether or not any metal is near the sensor. I believe that may be because the setup in that link is an NPN output NO (Normally Open) sensor, and my sensor is NC.

When I have used this type of sensor before, I used a resistor divider to set the sensor output to an appropriate level, but in that case, there was no hardware pullup on the control board I used. Given that pullup, I do not know how to calculate an appropriate resistor divider for this sensor.

How can I connect this sensor to get the appropriate (3.3v/5v) logic output?


texts: Is it normal to have a rats-nest of VCC/GND traces under an IC?

texts:
I'm attempting to route a simple board, the first I've done in 15 years since I routed a 12V linear power supply in the equivalent of mspaint. This board consists mainly of an LPC2387, which is an LQFP100 IC that requires a variety of +3.3V and GND connections.

As I play around with routing the traces for this thing, it strikes me that even with only GND routed, the underside of the IC is it's own little rat's nest of traces. Using this strategy, I'm going to need a giant pile of vias under there just to power the IC.

Is this normal? Am I going about this all wrong?


texts: Simulation for a transmission loop using PowerWorld

texts:
I am now learning how to use PowerWorld Simulator. However, I faced some problems when I tried to enter the data given in the paper.

I want to simulate the following transmission loop:

First things first, you see the generator ratings? (\$x_0\$, \$x_2\$ and \$ x^o\$)? How can I implement these data into the simulator? I went through all the options, but I couldn't find anything:

As for the transmission line ratings, I see there are \$Z_0\$ and \$Z_1\$. What are they? And how can I enter these data into the program? There is only one place for one:

In any case, I need someone to simulate this program using the PowerWorld software and upload it.

(Note: all data should be in per-unit)

EDIT

Whenever I try to run this simulation, I get this message:

Any clue?


texts: Can I safely enclose battery-powered electronics in an antistatic bag to protect it from static electricity?

texts:
I am building an enclosure for a Beaglebone and external circuit that I want to be able to wear, and therefore want to be lightweight and somewhat comfortable. I power the Beaglebone using a battery pack that's about 5 volts.

Right now, I enclosed the Beaglebone and the external circuit within an antistatic bag. This is the first layer of protection. I enclosed the antistatic bag with a jersey fabric material. The jersey fabric material has Velcro attached to it and is attached to a Velcro belt.

Is the powered Beaglebone circuit safe within the antistatic bag? Antistatic bags are slightly conductive according to the Wikipedia article, so I am unsure if this a safe solution. If not, what is a good insulating material? Rubber?


texts: Horn disturbs controller and lcd on common power source

texts:
I have a 60V battery which feeds a PCB itself switching down the voltage to a 12V bus and then from 12V to a 5V bus using two consecutive TI TPS54560 switching regulators (5A max current). I have a MCU connected to a LCD powered by the 5V bus. The 12V bus power the front lights, back lights and a horn.

Everything works fine but when I power the horn, for some reason the screen becomes empty or displays random characters. However, the second I input an analog signal into the adc of the MCU then the screen starts displaying the correct data again. The horn is a 12V 1.5A 105dB standard universal horn. Here is a simplified diagram of the circuit:

simulate this circuit – Schematic created using CircuitLab

If you need more information or clarification do not hesitate!
Thank you for your help!


texts: On Eagle, I was told that one of my parts was a 10uF cap that was of the EIA3216 package. Can I know what this is? I tried to find such a part online but was unable to do so.


texts: SD card initialisation problem with Atmega32u4

texts:
I have had this issue for the last couple of days and I cannot solve it. There are many similar issues I've read through online but they have not really worked for me.

This project involves a PCB and doesn't use the Arduino type SD card breakout although it is Arduino based.

In the microcontroller schematic I have ticked in red marker the connections from the microcontroller to the SD card

I am using the original chip select pin SS (CS_1) for the SD card, and PB4 (CS_2) as the chip select for a CAN controller.

I am fairly sure the SPI interface is working OK because the CAN controller initialises (if I purposely use the wrong SS pin for CAN, it throws an error)

The SD card schematic is also attached. Basically CS_1 from the micro goes to HC4050, and this is level shifted (CS_µ) to the SD card reader. Similarly for MOSI and SCLK. I have not level shifted the MISO line because a schematic I found online earlier did not do so either (but I have forgotten which schematic it is now...) I did check the adafruit SD card breakout schematic and they don't appear to level shift MISO.

Both the SD card reader and the HC4050 receive 3.3V when tested with a multimeter. For further testing I borrowed an Arduino MICRO from a friend and hooked up an Arduino style SD card breakout, ran the same code and it worked fine.

I used an Arduino MICRO for testing because the microcontroller on the PCB has the same bootloader flashed through the Arduino IDE.

The thing to note is that the SD card breakout is not exactly the same implementation as the adafruit or mine as it uses an LVC125 Buffer and a bunch of resistors instead of the HC4050

It looks like this:
https://howtomechatronics.com/wp-content/uploads/2016/08/Arduino-SD-Card-Module.jpg

Code for initialising the SD card is as below, I am using the SD.h library.

//SETUP microSD CARD
  if ( SD.begin(  ) )
  {
    Serial.println( "SD card initialised" );
  }
  else
  {
    Serial.println( "Unable to initialise SD card - check connections" );
    errorState();
  }

After soldering some wires to check the SPI lines with a logic analyser, it appears the MOSI, SS, and CLK lines are working correctly, but MISO always stays high (never responds to the request sent through MOSI)

The only time I saw MISO going low is during flashing or power-up.

I also did a continuity test from each solder pad of the SD card reader/slot to the corresponding pin. I was expecting roughly 0 - 1 ohm but was surprised to see each pin had a resistance of 30 ohms to the respective solder pad. Is this normal?

I am not sure what is going on, any insight would be appreciated.


texts: Voltage Limitations of a header being used as a voltage selector

texts:
I have an application that takes a reference voltage. These voltages could be considered 'low voltage' as they range from 0 to 1000 V. Below is a reference schematic of what I'm trying to accomplish, demonstrating with two input voltages:

simulate this circuit – Schematic created using CircuitLab
The idea is that I use a selector to select a reference voltage that goes to my output. To accomplish this, I'm planning to use this male header along with a jumper to jump pins together. With the voltage rating being rated for 1000 volts in this case, and considering the voltages I am working with, would a header work here, or are there other more common methods of creating a selector?


texts: How are the prepreg & core selected for a 6 layer (1 oz each) and 93mil PCB thickness?

texts: I would appreciate your help.  How is defined the number of prepreg and Core dielectrics for a 6 layer (1 Oz each) and the total 93 mil tickness of the PCB?


texts: How can one battery provide multiple voltages

texts: A battery such as this is able to provide multiple different voltages based on user input. Given that the textbook battery provides a fixed voltage, how is this achieved? Are there multiple cells which are connected up together differently depending on the requested voltage or does it work in a different way?


texts:
I'm designing a board with a STM32F103CBT6 chip and I've been trying to figure out how USB works so I can have that extended out. Reading some specifications online has just left me with more questions. From another stack overflow question I got these 2 documents which I'll be referencing in my questions.

Fairchild Specifications
Semtech Specifications

Questions:

Can 2 USB devices talk to each other if both of them are designated as "Downstream" or "Upstream" devices? 2
Rpd and Rpu from 2, are they independent of of Vdd or will they change if your device is running off a different supply voltage?
If I'm understanding the Termination resistance correctly, one side of the system has to have 45ohms and the other side equally has to have 45ohms for a total series of 90ohms as specified in 1. What happens if a long cable is involved between the 2 systems and added more resistance? Would USB communication stop working?
How do I actually calculate Rs needed to add on the D lines? Are they specified somewhere in the STM32F103 manuals? I've been working from the hardware design guide, reference manual and datasheet for the chip but haven't seen anything on it.
The reference manual for my chip specifies it's USB2.0 full speed, which 2 says is 12Mbps communication, however the STM32Cubef1 setup program says 48Mhz is required for the USB clock, why the discrepancy between clock speed and data transmission?


texts: How to calculate neutral base width for an emitter-base junction with forward bias voltage

texts:
I am trying to find the neutral base width for an emitter-base junction with a forward bias of 0.75V and a base-collector junction reverse bias of 20V.
I am not sure how to factor in the forward bias voltage and the reverse bias voltage into my calculation. I know that the neutral base width is the base length minus the depleted parts but I am lost after that.
Please be as detailed as possible in your explanation, I am new to semiconductor physics.


texts: Is it ok to supply 24 volt from the power supply with output 24 v 10 Amps to sensor which current & Voltage consumption (max) is 12-30V 35mA

texts: Is it ok to supply 24 volts from the power supply with output 24 v 10 Amps to my sensor which voltage supply range+Vs is 12-30 V and current consumption (max) is 35mA, will current output from the power supply (10A) will destroy my sensor ??


texts: Does applying dc bias to a signal make it stronger?

texts:
I worked on a device that mimics a triode vacuum tube. But it doesn't use any vacuum, instead, it uses an electrolyte. I got several of them working, and I can make them switch, by making the "grid" positive.

You'll see, it has two wires, and a serpentine-shaped one, that's my grid. If a current runs between the two plain wires, another running between one of them and the grid (that is placed in the middle) can control the other. Just like in a normal triode vacuum tube.

I've reached current gain.

But I want it to amplify analog signals, rather than only switching digitally. So I hooked up everthing as it shows:

simulate this circuit – Schematic created using CircuitLab

The microphone and the battery attached to it are an Audio source.

By making the grid positive, I noticed that the signal sounds a bit louder.
But I think I'm applying DC bias. Because I put a LED in series with the speaker and it shined all the time, but still followed the signal.

And if you simplify the circuit, I'm just putting the battery in series.

So, First: Am I applying DC bias? and Second: Does the DC bias make the signal louder?

Anyway, I hope this is understandable. Thanks by now.


texts: WeMos D1 rebooting 2-5 seconds into driving stepper motor

texts:
I've set up a basic stepper motor rig with most commonly used components and L298n as a driver, WeMos D1 (ESP8266) as a controller: https://imgur.com/a/wHgOW

Programm is supposed to hit limit switch under the belt (works) and then move all the way to the top (reboots half way).

I've tried powering this up with a desktop power supply, and even powering stepper and WeMos with 2 separate batteries - same rebooting problem.

Any advice? Thank you.


texts:
I was searching the internet for a circuit to generate a pulse when its input is held  high, and I came across this circuit:

I tested it and it works like a charm.
What is the purpose of the last two transistors on the left? (Q3 and Q4)
I think they make a Darlington pair,  but what is its purpose here?
I tried the circuit without it and it works without a problem.
I am new to this so please help  me understand.


texts: circuit analysis with dependent voltage source

texts:
The question is:

The solution is as follows:

Everything is clear. I am only confused how he solved for "Loop 2:" in his solution. Below is my attempt kindly advise me of my mistake.

We know that  does not equal $$I_2\ne\frac{1}{2}*I_4$$, Because $$\frac{1}{2}*I_4$$ is a VOLTAGE and not a CURRENT. so, how are they equal?
This is my confusion.
The question and answer are from: FE Exam Review: Electrical and Computer Engineering 1st Edition by Myron E. Sveum Publisher : Professional Publications, Inc. ISBN-10 : 1591260698 ISBN-13 : 978-1591260691


texts: single zero in z-domain transfer function calculatio

texts:
I am designing a filter with two poles at DC and one zero at fs/10. For simplicity I choose fs=1; So my z-transfer function looks like: (z-z1)/(z-1)^2. Since z=exp(jwT)=cos(wT)+j*sin(wT). So if I want to place my zero at f=fs/10 then how I can calculate the value of z1?
Since it is a real value it doesnt have jsin(wT) then I cannot use simply cos(wT)=fs/10. Please help in understanding how the real zero is calculated.
I have attached the matlab pole zero response of the function which say that z=0.533 will give me a zero at f=0.1fs(My fs=1).

Regards


texts: How to use Millman's theorem to solve this question:find the voltage value

texts:
The question wants me to calculate the Vc

simulate this circuit – Schematic created using CircuitLab

And here is my thinking:

These arrows are the current flowing direction i think,and i think the V1 is 12V,and V6 is 2V. i want to use Millman's theorem to solve this problem

simulate this circuit

My formula are as below:

\$\frac{12-Va}{8}+\frac{Vb-Va}{5}=\frac{Va-2}{2}\$,that is, \$100+8Vb=33Va\$
\$Vc=5+Vb\$,\$Vd=15+Ve\$

unfortunately,i stuck here,does anyone know how to calculate the Vc value by using the Millman's theorem ??


texts: Altium Designer: Modify IC symbols in-sheet to increase space

texts:
I am using some schematic symbols for TI devices that I converted to Altium using the Ultra Librarian Software as "instructed" by TI.

However all of these symbols are too crammed, I already have trouble attaching the rudimentary decoupling capacitors to the pins.

I could of course change the symbol in the library, however this would be a very time consuming iterative process until it fits my schematic. Is is possible in Altium to "in-sheet" redesign the part symbol?

Example of crammed component:


texts:
I'm on the process of building a new version of my ebike electronic systems and I'm searching for a way to lower the voltage of the battery (13s = 54,6v fully charged) to 12v/5v for the accessories and various electronics.

I would like to keep my main microcontroller (which is a STM32 based board) powered at all time (with sleep modes) to be able to get GPS, GSM and battery monitoring running when necessary, and then switch (with mosfets/relays) the bigger loads if needed. Given that I would like to keep the thing connected all the time, because my battery box is screwed, I would like the quiescent current to be as minimal as possible, to avoid any unnecessary current consumption.

So i started to dig up in my boxes to excavate various DC to DC converter I have, and found 3 of them which I tested on my PSU at 54,6v input :

RCNUN E-Cart Fixed 12v, 10A : 15mA quiescent current
SUKUZU Fixed 12v, 10A : 8mA quiescent current
LM2596HV variable buck 3v-48v, 3A : 5mA quiescent current.

Given that my battery bank is around 15Ah, 5mA would not be really dramatic, you could still run the thing for more than 4 months. But I'm trying to find a more efficient way to do it. So I looked at Ti's website and found this little chip : TI LM46002

Which provides pretty impressively low quiescent current : less that 30µA.

But I was wondering if it would be the correct way to go and if you had simpler way to get a 12 or 5v out of 60v max battery bank.

I hope my question is clear and that it's not a repost, I searched on the forums, schematics and stackexchange, but I might have missed the perfect answer.


texts:
What does the line to line voltage mean?

For WYE connection is Vna line to line or Van?

How about Delta connection?


texts:
I'm not posting this on drone SE because I think this has more to do with electrical stuff than flying drones.

I've been flying my drone around a bit, and most of the time I screw on an antenna. The picture is always clear, or as clear as it normally is, and everything looks fine with the antenna. Then one day I realized that I hadn't even put on the antenna and the picture had been the exact same. I thought maybe I was just not remembering differently, but when I watched the video while removing/adding the antenna, the quality was still the same. This made me wonder,
Do screw on antennae actually do anything?


texts: Time response of LM317 used as current regulator?

texts:
My Vin=10VDC and my R1=1.25 ohm.

If I have a 'load' of 1 ohm, what is going to happen?

Initially, will the current be above 1A and settle down to 1A. Or will this actually limit the current to 1A. What is going to happen to the voltage through the circuit. My 'load' will have 1V drop across it, with 1.25V across R1, and ~3V drop across the LM317. Just based off these simple calculations, does that mean my Vin is really only going to be 5.25V?


texts: Measuring Energy (Watt-hour) from Microcontroller

texts:
I have microcontroller device (ESP32) that doing some process and the begin to sleep. This cycle is for 12 hours (00:00-12:00). And after that, begin full sleep for 12 hours (12:00-00:00). So my timing diagram will be like this:

and then i calculate average power drawn each day, like this:

P = V * I(average current each day) = 5V * 12.25mA = 61,25 mWatt

So, to calculate energy (watt-hour) consumed by my device is, i need to multiply it by 3600s, like this:

E = 0,06125 * 3600 = 220,5 watt-hour

Is this correct?


texts: Cheap PWM Charge controller not charging the battery

texts:
I recently got myself a CMG-2430 PWM charge controller(pretty cheap I know) and a 12v deep cycle battery. The problem is that the charge controller doesn't charge the battery when I connect the solar panel. ....I know that is a cheap solar charge controller but I really what to ask you guys about opinion because I might just have missed something simple. Here are all the informations about the solar panel, charge controller and battery and after that I will give some more info about the problem.

Solar panel
Pmax: 20.0 W
Ipmax: 1.20 A
Vpmax: 16.9 V
Isc: 1.24 A
Voc: 21.5 V

Battery
Voltage: 12 V
Capacity: 20 Ah
Initial current: less than 5 A

Solar Charge Controller  (CMG-2430)
Voltage: 12V/24V automatic
Current: 30

Now, when there is no sun (or the solar panel is disconnected) it show's the moon symbol and when I connect the solar panel it does change to the sun symbol but shows 0.00 A even in full sun, and when I check the current on the battery it does confirm that is not charging. Maybe you guys have an idea of what could possibly be wrong.

update:

I did find the problem....I finally opened the controller and guess what. ...it has a black spot and a burned moosfet near the solar input. ....thanks everyone anyway!


texts:
I recently purchased a 110VAC solenoid and wanted confirm the best way to power it (see link below):

https://www.amazon.com/gp/product/B00DQ1MEVS/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

The solenoid has a 12W power rating. Would I be alright if I powered it from a typical 120V wall outlet? Would the using a 120V power source for a 110V solenoid have any negative consequences? From what I have gathered, AC solenoids self-limit the amount of current they draw once they open. Is my thinking correct? I am only planning to open the solenoid for a short duration each use (<5 seconds).

I am sure this is a very basic question for someone with electronics experience, but I would certainly appreciate any responses to either direct me or put my mind at ease. Thank you for your time.


texts: Understanding function generator output when units are in dBm

texts:
I am using a function generator with output in units of dBm. It has an output impedance of 50 ohms. I am measuring this output on an oscilloscope, and am failing to understand the waveform's amplitude.
With the scope input impedance at 50 ohms, a 0 dBm signal has amplitude ~640mV. A 10 dBm signal has amplitude ~1.28mV.
With a scope input of 1M ohms, a 0 dBm signal has amplitude ~2.04V. A 10 dBm signal has amplitude ~4.08V.
I would expect at 1M ohm input impedance and with 0 dBm, to get an ~0.244 V amplitude, yet this is not the case.
Would someone be able to explain this behavior?


texts: Battery heating up instead of a coil in a simple heat circuit

texts: I am making a simple heat circuit using 9v battery and a coil made up of AWG 18-gauge copper wire (electrical engineering newbie working on a fun project). I followed these steps http://www.ehow.com/how_10022230_make-heat-circuit.html but what happens is battery heats up instead of a coil. Looks like battery is shorting. Can anyone suggest how can I troubleshoot the problem? I kept the circuit connected for about 2 minutes but after that coil didn't heat up at all but battery was noticeably hot!


texts:
I'm looking to build a board using a xilinx xc3s50a fpga and using a static ram chip of some kind. Perhaps something such as the GSI Tech GSI71116A.

My worry is about the data lines of the ram chip. If I make a mistake on my verilog I could easily do a read cycle from the chip while outputting data from the fpga. I don't imaging setting a '0' on the fpga and a '1' on the ram chip, or the reverse would end well...

So basically I'm looking for information on what would happen? Is it likely to damage either or both chips or are they protected against this kind of thing by limiting the current? If the answer is no, could I protect myself by adding a small resistor in each data line to limit the current? While that would probably work electrically, I'm not sure what effect that would have once it's working and I need to send data at up to 100Mhz.

So basically, do I need to protect myself here? Can I protect myself? Or do I simply need to be really careful with my verilog code not to enable output on both devices at the same time?


texts: Create circuit from current–voltage characteristic 2

texts: Why is there a need for a current source in an electric circuit? As we know without voltage there will be no current flow then why do we call it current source? Why we do not use voltage in place of current?


texts:
I see here (Battery University) and here (Electrical Engineering StackExchange) some claims that it is indeed possible to charge lithium ion batteries at -30°C if you do so at a 0.02C rate, but I don't see any hard evidence to support these claims. Like research papers, datasheets, whatever. Anyone know?

I'm developing an outdoor solar-powered product that will be charging all year 'round, even in the winter, even in colder climates. The 0.02C rate is acceptable to me but I don't want to proceed unless there is validation that I can indeed do this without either impacting battery life or causing a safety issue.


texts: Did I understand this diagram correctly? How do you put a load on a positive wire?

texts:
Sorry I mixed up the two diagrams, I thought both diagrams were using FETs on the right side.
I am trying to turn on a 5V separate power source with a 3.3V GPIO output.
I have two separate circuits, the 3.3V one is a deep sleep ESP-01 that's turning on a bigger microcontroller with its own battery/bunch of sensors.
So I'm doing the NPN to PNP switch approach.
I found the diagram on the right after someone suggested I use a high-side switch approach(I was using low side before and I was having weird power problems).
I also have IRF9640PBF MOSFETs if those are better.
As mentioned I don't understand how you put a load on a seemingly positively wire (right image below +12V). I'm assuming the LOAD would be my second circuit/larger microcontroller.
Thanks for any help
edit: I have the wrong diagram on the right, I updated it. I'm updating my MS paint circuit.
Going to try this, matches left-most diagram

That's not good, the step down converter started squealing haha.
You are failing doctor...

Well I gotta go through this some more, figure out what's going on.
This one the step down regulator is happy, however I can't tell if my electronic switch is not working or it's just literally not connected (MOSFET source). The IRZ44N needs a 4V gate threshold not sure if that's why, will try it with my power supply. I'll respond to this when I figure it out, seems like I gotta go back to the basics.


texts: Need guidance for building a electronic load using BJTs

texts:
I've been studying DC electronic loads and almost all of them used mosfet as main transistor, while researching I find out that mosfets that are designed to work in their linear region are expensive and also it's not easy paralleling them because their threshold voltage can vary and we need one op amp for each mosfet.
Long story short; I decided to use BJTs instead of mosfet, below circuit is the raw idea that I end up with:

simulate this circuit – Schematic created using CircuitLab
I haven't built this yet but on the simulator even when the load is not connected, the circuit is drawing some current from the source:

How can I compensate for that extra current or can I somehow null it out?


texts: Is a more expensive DAC guaranteed to be more efficient for audio applications?

texts:
I designed an audio circuit on a breadboard using a DAC with DIP packaging. The quality is ok except for a few artifacts I'm currently attributing to analog and digital power being too closely intertwined.

For the PCB I'm going to make, I'm deciding between 2 surface mount DACs of higher quality that appear to be similar in specs to each other but differ in price by a factor of 10. My question is what could cause the huge difference in price between the two seemingly similar devices?

The two devices have the following specs:

               MCP48FVB21    AD8300ARZ
num bits        12            12
num converters  1             1
Settling time   7.8us         14us
INL/DNL         1.5, 0.2      0.5, 0.5
Vdd             2.7-5.5V      2.7-5.5V
Architecture    R2R           R2R
Voltage buff    yes           yes
Comm rate       20MHz         25MHz
Latch pin       yes           yes
Size (mm)       3 x 5         5 x 6
Pins            10            10
Price           $1.38         $13.07


texts:
I have hooked up the following circuit:

Also, is there any possibility to create a link for the schematic? After posting it I realized it´s too small to be seen but I don´t know how to fix it.

simulate this circuit – Schematic created using CircuitLab

It´s a simple current source that charges C1 to reach a certain value and saturate OA1 positively to get around 3.7 Volts in its output.
Q2 and Q3 form kind of a flip-flop circuit, where the voltage V1 is the output, and it´s set on when V2 is High(3.7 V). Soon after, as a result, V1 will remain on regardless of the state of V2.

Done that, V1 ~ 4.9 V. It will  discharge C1 via Q4, and hold Q1´s collector close to 0. But that´s still not the problem.

The problem is:

When V1 ~ 4.9V , it´ll start charging C2, and the same thing should happen(now, set Vout ~ 3.7V), but the voltage across C2 reaches 1.56V and sometimes even 1.57V, though it can´t go over.
I tried replacing the op-amp and capacitors but nothing changed.
Additionally, when I disconnect V3 from Q6 collector, the circuit works in the expected way( the capacitor reaches 1.56v and latches on the op-amp to positive rail).

So from my first thought what might be causing a problem here is the trial to discharge C2 via Q8. But I don´t know why is that since V1 can easily discharge C1 by the same method.

simulate this circuit

Am I missing something?


texts:
Im trying to load 2 values in assembly under the tm4c1294ntpcd (Cortex M4) then add it with the next code

    .global main
        .text
main
        BL  LRut

LRut
        LDR r5,=2172428;
        LDR r6,=0x7CD32A58;
        ADD r0,r5,r6;
        STR r0,[r1];

END

But it keeps saying errors like Unknown Marker, Unexpected trailing operand(s), and Bad term expression on the LDR lines, isn't the syntaxis

LDR <Rd>, =<numeric constant>

Then what its wrong?


texts: How does this audio power amplifier circuit work?

texts:
How do I simulate an audio amplifier in Multisim?

I'm required to search for audio power amplifier circuit and explain how it works in details so I need to know the detailed process of this circuit and understand how does it work?
also I found this circuit from here SE


texts: Convert 5V to 3.3V without logic level converter

texts:
I've got a 2.2 SPI monitor (QVGA TFT monitor & SD Card), but I am using Arduino UNO board. All pins are 5V. How can I use a resistor to communicate between TFT, SD and UNO?

I have lots of different Ohm resistors, and have 3 Logic Level Converter (non bi-direction).

I try the LLC connect to TFT, but no luck, it just has the backlight ON, nothing I can see.

Thanks TJ, I had wired with this circuit, but the voltage seems not enough 3V. Am I something go wrong?

simulate this circuit – Schematic created using CircuitLab

Also, I have try to change R1 to 330 ohm & R2 to 680 ohm. Seems also cannot convert to 3V / 3.3V


texts:
I'm trying to decode a RS485 bus from an alarm system.  If I connect it to a computer on baud 3600 then I receive ASCII strings which match what is being shown on the alarm panel; however, when I look at the signalling from the microcontroller to the line driver, this is what I see:

The period between the two gray dotted lines is 2ms.  It looks more like manchester encoding to me, or otherwise there are too many bits and the pulse widths vary irregularly from what I can see.

Is anyone able to help me with what is going on?  It decodes ascii strings with a PC uart converter, but I'm trying to identify the characters that start and end the packets so I need to be able to read the trace but I am perhaps decoding it incorrectly?

I read it as 1001001001011011010010, which is more than 8 bits.  The widths of the smaller pulses are akin to 9600bps but I cannot understand why I am receiving usable ascii at 3600bps.


texts: How do I connect noise reduction capacitors for "stacked" TI REF102 chips?

texts:
The datasheet for TI's REF102 shows a method for "stacking" multiple ICs to obtain voltages in multiples of 10V. Two stacked REF102 ICs gives you 20V, 3 gives you 30, etc. I've tried hard to copy the schematic correctly below from the datasheet.

My question is about how the noise reduction capacitors (NR is pin 8 on the IC) should be connected, which the datasheet doesn't seem to mention - at least not in this stacked scenario. The connection for the "first" IC (the lowest one in the pic that's outputting 10V) seems obvious, so I just drew it in there. But what about the capacitors for the 2nd and 3rd ICs? Should those go to their own common (which is connected to V+ on the chip "below" it)? Or should they go to the common ground, just like the first chip?

simulate this circuit – Schematic created using CircuitLab


texts:
When I put my IR remote near any AM radio and push any button on the remote, I can hear a sound from the radio speaker (like beeping). This phenomenon is very weird for me because the radio has no IR receiver inside.

On the other hand, the frequency of the AM radio is more than 530 kHz but the frequency of the IR remote is usually only 30 to 38 kHz.

Furthermore, the human ear can't sense frequencies higher than 20 kHz but the frequency of the IR remote is more than 30 kHz.

So, I'm wondering why do AM radios react to IR remotes?


texts: Bad oscilloscope probe does not measure DC

texts:
I seem to have messed up my oscilloscope probe during PCB testing. Too high a voltage was applied and there was arcing between the probe and a pin on the PCB. The probe can still read square waves very well (using the compensation terminals on the oscilloscope and a 115V square wave on the PCB.) The problem arises when i try to read a DC voltage.
When trying to measure the switching on of a 115VDC output, I get a signal that rises up to 115V, then slowly comes back down to 0. (The DC source keeps on outputting 115V,1A so the output is definitely active).

Also, when measuring a 12VDC supply, i get the following sinusoidal waveform.
I have opened up the probe and the resistors and capacitors seem fine (no broken chips and no heat traces). I am looking to understand what is happening with the probe and repair it if possible.
The probe model is the RP3500A passive probe from RIGOL.
PS: I have measured the previous waveforms with another probe using the same oscilloscope channel and i get a clean switching on of 115VDC and a constant 12VDC.
Thank you!


texts: How can I power a 3.3v circuit with a 9V power supply and two AA batteries?

texts:
I have a circuit that runs on 3.3v. I want it to be able to operate on two AA batteries down to about 2.2v (or until batteries are dead), and also with a 9V power supply. When the power supply is plugged in, the batteries should be disconnected.

The power jack being used has a switching ability, and would work fine if both power sources were at the same voltage. But when battery power is active, the voltage must be boosted to 3.3v, and when the power supply is plugged in the voltage must be regulated down to 3.3v.

I've not been able to find a single chip that will accept 2-9v and regulate at a 3.3v output.

What other solutions are there? Minimal parts count and cost is certainly preferred.


texts:
When there is no channel length modulation there is infinite channel resistance according to relation :
rds = 1/lamda * Id..So does this mean that drain current is zero ?


texts: Why do drones use Li-Po instead of Li-Ion?

texts:
According to every source I've found the only advantage of Li-Po is their shape, but they are more expensive, have lower energy density and are more dangerous compared to Li-Ion.

Why do drones use Li-Po batteries instead of Li-Ion batteries for example 3s2p 18650 Li-Ion with 40A protection circuit.


texts: Can I use two identical bluetooth modules in the same area?

texts:
The modules I'm planning on using are the BlueSMiRF Silver Modem's shown here... http://www.sparkfun.com/products/10269.

I got one of them to work successfully but I want to make sure I can use two within the same area before I buy another one.


texts: SMPS Testing: Differential Probes or Common lead and best Grounding practice

texts:
I'm testing a Switch Mode Power Supply that is not outputting the required voltage. It's only two prong, hot and neutral, and I wanted to get clarification on the best way to approach measuring the hot and cold sides respectively with my oscilloscope. The usage of the circuit is to charge a +12V battery. Just so it's clear, I'm an instrument technician by trade so I'm familiar with the dangers of mains voltage, 120VAC in my case, but I'm a few years out of school so I'm rusty on the usage of my scope.

First question is this: Even with a two pronged mains input, is an isolation transformer still needed?

When probing the hot side of the transformer, if isolated, can I use the common lead on my probe or will I need a differential probe since there's no ground and the reference will be neutral mains or the negative output of the full wave bridge rectifier?

Lastly, in this instance would I be able to use the "Bat-" as my ground reference for the cold side with my common lead on my probe?

Thank you everyone for your time and please let me know if I wasn't clear enough about something.

This is the SMPS that I'm testing at the moment, which is used as a +12V battery charger: -


texts: Calculating wattage of electrical appliances

texts:
I need some help from you. I don't know how to calculate wattage of my refrigerator. It has a warmer part and cooler part. Below is its configuration.

Also, if you guys don't mind, please roughly explain me on calculation of wattage of various electrical appliances. Or please share some pdfs on this topic.
Thank you.


texts: Explanation of Expressions of the number required of independent equations to analise a circuit

texts:
The expressions
\$N-1=\# KCL \$
and
\$E-N+1=\# KVL \$
(where \$N\$=number of nodes; \$E\$=number of elements on the circuits) gives us the linear independent equations on a circuit.
But sometimes the expressions gives me, for example, 5, and I only have 3 unknowns. So, why is this wrong? What do the value of the expressions tell me? The independent equations I can write, or the independent equations I will need to analyze the circuit?
What about nodes? Are they the theoretically nodes or the practical nodes? I always consider on this expressions the theoretical nodes. I mean, it doesn't necessarily have to be a current divider, it can simply connects 2 elements of the circuit.
These equations aren't very accurate to me, and I would like you to help me figuring it out why.
Per example:

Here I have 8 nodes and 10 elements, so I got 7 independent KCL equations and 3 independent KVL equations, but I only want to know I,I1,I2,I3,I4,I5, so I just have 6 unknowns.
Why I have more equations that unknowns? How can I select the 7 KCL equations in order to don't get dependent equations?


texts:
I've wired up a 3x3 matrix as in the attached image. My understanding is that if I apply 3.3 volts to row C and connect column 1 to ground, the electricity should flow through the bottom-left LED (as in the top-right of the image), turning it on. What seems to be happening, though, is that the electricity bypasses the LED and flows directly to the ground, meaning no LEDs light up (as in the bottom part of the image). This makes sense to me since electricity usually follows the path of least resistance. But everything I am reading online seems to indicate that what I am trying should light up the LED. What am I missing here?

I should also note that I have a 100 ohm resistor at the beginning of each row.


texts:
When I have a datalogger and I want to sync a video-file to the recording, what would be an easy method? The logger and the camera both have an internal clock, but they may not be set exactly to the same time, so I cannot use those timestamps to sync the start, and during long recordings they may drift apart.

The solution seems to be to let the datalogger record an extra sync-signal, but what should this channel contain (no. of frames?) and how do I get this information from a regular camera?


texts:
A prototypical capacitor consists of two electrodes in parallel separated by a nonconducting dielectric material. What is the difference between a conventional capacitor and a supercapacitor?
It seems that conventional capacitors usually have solid dielectric materials, like polymer films, ceramics, or glass.  But is this always the case?  (I guess one possible exception is an electrolytic capacitor, such as an aluminum electrolytic capacitor.  But in that case, it seems that it is an electrode that may be in the liquid phase, and not necessarily the dielectric separating the electrodes.)
Supercapacitors are more technically known as electric double layer capacitors (EDLCs).  An electric double layer forms at the interface of the electrode and the dielectric.  It seems that in a supercapacitor, the dielectric is usually a liquid.  But is this always the case?
Can it be said that the difference between a conventional capacitor and a supercapacitor is that

a conventional capacitor has a solid dielectric, whereas
a supercapacitor has a liquid dielectric?

I would appreciate it if anyone could share an academic resource -- book or journal article -- that explicitly states the difference.
Incidentally, the journal article here (Olabi, Energy, 2021) states:

Due to solid dielectric between the electrodes, supercapacitors store energy by means of an electrolyte solution between two solid conductors.

I wonder if they made a typo in that sentence.


texts:
I have made a soil moisture sensor by taking two lines of Veroboard and soldering a wire to each line. The theory is that the resistance will change with the moisture - resistance dropping as the moisture rises.

However, with my new LCR meter, I am getting a difference of a whole megaohm depending on which range I use to measure it.

What result should I trust?

  Notes:
  Using a regular multimeter is not an option. My regular multimeter is very old and imprecise and I am a poor student who wants to finish this project before his significant other's birthday.


texts: Is it sensible to always use larger diameter conductors for carrying smaller signals?

texts:
This question as originally written sounds a little bit insane: it was originally asked to me by a colleague as a joke. I am an experimental NMR physicist. I frequently want to perform physical experiments which ultimately boil down to measuring small AC voltages (~µV) at about 100-300 MHz, and draw the smallest current possible. We do this with resonant cavities and impedance-matched (50 Ω) coaxial conductors. Because we sometimes want to blast our samples with a kW of RF, these conductors are often quite "beefy" -- 10 mm diameter coax with high quality N-type connectors and a low low insertion loss at the frequency of interest.

However, I think this question is of interest, for the reasons I'll outline below. The DC resistance of modern coax conductor assemblies is frequently measured in ~1 Ω/km, and can be neglected for the 2 m of cable I typically use. At 300 MHz, however, the cable has a skin depth given by

$$
\delta=\sqrt{{2\rho }\over{\omega\mu}}
$$

of about four microns. If one assumes that the centre of my coax a solid wire (and therefore neglects proximity effects), the total AC resistance is effectively

$$
R_\text{AC}\approx\frac{L\rho}{\pi D\delta},
$$

where D is the total diameter of the cable. For my system, this is about 0.2 Ω. However, holding everything else constant, this naïve approximation implies that your AC losses scale as 1/D, which would tend to imply that one would want conductors as large as possible.

However, the above discussion completely neglects noise. I understand that there are at least three main sources of noise I should consider: (1) thermal (Johnson-Nyquist) noise, induced in the conductor itself and in the matching capacitors in my network, (2) induced noise arising from RF radiation elsewhere in the universe, and (3) shot noise and 1/f noise arising from fundamental sources. I am not sure how the interaction of these three sources (and any I may have missed!) will change the conclusion reached above.

In particular, the expression for the expected Johnson noise voltage,

$$
v_n=\sqrt{4 k_B T R \Delta f},
$$

is essentially independent of the mass of the conductor, which I naïvely find rather odd -- one may expect that the larger thermal mass of a real material would provide more opportunity for (at least transiently) induced noise currents. Additionally, everything I work with is RF shielded, but I can't help but think that the shielding (and the rest of the room) will radiate as a black body at 300 K...and therefore emit some RF that it is otherwise designed to stop.

At some point, my gut feeling is that these noise processes would conspire to make any increase in the diameter of the conductor used pointless, or down right deleterious. Naïvely, I think that this has clearly got to be true, or labs would be filled with absolutely huge cables to be used with sensitive experiments. Am I right?

What is the optimum coaxial conductor diameter to use when carrying information consisting of a potential difference of some small magnitude v at an AC frequency f? Is everything so dominated by the limitations of the (GaAs FET) preamplifier that this question is entirely pointless?


texts: Three different schemes to amplify audio input, which one is correct?

texts:
I'm building an audio amplifier (prototype) with display and MCU (Arduino Nano), see photo below (not finished ;-) ).

On the display I want to show some VU-meters of the input but there are different implementations how to do this.

Some claim that you can connect the audio input directly to the pins of Arduino which I have tried but doesn't seems to work. Other claim it is not a good idea to do it that way because there is no circuit seperation or claim that it is impossible because the signal is AC and is too weak (like I just discover, just a few millivolts and Arduino can't measure that).

So I found a few solutions to amplify the signal with use of decoupling and a voltage divider. The voltage divider pull out 2.5V at maximum at a input voltage of 5. The arduino is able to measure this.

Question

The solutions I found are a little different so the question is, which one should I use? Why are they different? Which one is the best to use to show a VU-meter?

Found solutions

Resources

1. Arduino Audio Input http://duino4projects.com/audio-input-to-arduino/

2. http://www.georgegardner.info/electronics/class-d-avr.html

3. DTMF detection library http://forum.arduino.cc/index.php?topic=121540.0


texts: Help figuring out the interface on this bill validator?

texts:
I would like to interface this bill validator to a microcontroller (Arduino Mega). The website says it supports RS232,RS485,Optoisolated RS232 and USB interface.

The one I have is currently intefaced with a parking meter controller, with four wires. I figured two of these are power (+24V and GND). The other two wires are at between -5.0-5.3V and -8.1-8.3V. Any ideas which interfaces this could be?

Thank you.


texts: transformer primary/secondary resistance don't behave by rules for me

texts:
I've got an RLC meter which I can set so it's a fixed AC voltage amplitude source.
I'm using a planar coil of 25 turns and in theory, when a secondary resistance increases, so should the primary. But this is not what I observe.

When the coil primary coil is isolated, the resistance is just the resistance of the wire, the reactance is high, so the current flowing is comparatively small.

But when I add a second planar coil on top of it, it decreases reactance, because the current in the secondary is flowing in such a way to create a magnetic field that is in the opposite direction from the primary, which reduces total magnetic field, reducing the reactance felt by the primary, which is why the current increases.

This is all fine, but I don't understand what is happening with resistance. Because it increases. And if I look at equations, it says that increase in secondary resistance should create an increase of primary resistance. Now if I add a resistor in series with the secondary coil, the reactance increases (less current is flowing which makes sense), but the problem is that resistance felt by the primary actually decreases. So adding resistance to the secondary actually DECREASES primary resistance felt, not increase it.

But in induction heating if we increase the temperature of the load (effectively increasing resistance) the resistance felt by the primary also increases. So why do 2 different experiments give 2 different results?

EDIT: I've done some more testing and found out that the resistance of the primary actually increases if I add resistors to the secondary to about the same resistance that the primary had on it's own. Any more resistance, and the primary resistance starts to fall. It has something to do with the power transfer but I don't know exactly how. And I'd like to find out.


texts:
I have a question regarding Field Strength: I was told it is independent from the frequency, is that true? If so, why?

Moreover, I came accross this equation for converting the Field Strength  to EIRP, but I do not get where the 104.8 comes from:

$$
E\ [dB \mu V/m] = EIRP\ [dBm] - 20 \log_{10}(d\ [m]) + 104.8
$$


texts:
I have designed a circuit that uses the TI CC1310 microcontroller, and has a daughtboard that has the PIR sensor and amplification circuitry from the from the TIDA-00489

http://www.ti.com/tool/TIDA-00489

When I look at the output of the amplification circuitry of the amplified PIR signal seems to look sensible. I have a nice stable line that sits at Vcc/2, until I move near the PIR sensor, at which point it goes to either Vcc or GND. All as expected.

This testing was done with my circuit being powered by a CR123A battery, and sat on a grounded anti-static mat. If I remove the grounding from the mat, or move the PCB off of the matt, the signal becomes very noisy. Rather than a nice thin line on the scope, I see a thick line that has ~0.5V thickness.

Additionally, I have an LED on the PCB, and I flash it every 1 second. When this happens, I see a sharp drop in the output signal of my amplifier every 1 second, seemingly corresponding with when my LED comes on.

Can someone please explain the causes of these noise sources to me, and let me know how they can be remedied?


texts: colpitts oscillator does not start oscillating when I add internal resistance of choke inductor

texts:
Everything works fine if I do not add internal resistance to choke inductor in my simulations. I get 10 kHz oscillation, but when I add internal resistance to choke inductor, oscillation does not start. I am using 5 mH choke inductor with internal resistance of 50 ohms. I do not know internal resistance of this inductor as I did not prepare it yet. I will take an iron nail and wrap wire around it till I get 5mH inductance. This is my plan as I do not have such inductor available to me. When I set its internal resistance to 30 or 40 ohms, the circuit is working fine. However, when I exceed 50 ohms, it does not start working. As I do not know what resistance my home-made inductor will give me, I have to speculate every scenario. I also checked the circuit to see if it stays in forward active region and it does so with 50 ohms of collector resistor. I am very confused. Can you help me understand this and give me some advice to make this circuit function better? If I can I would totally get rid of that choke inductor, but I do not know how to.
BJT has 300 current gain value and 0.7 V V-BE turn on voltage. 30k resistor is the load.


texts: How can I drive a bridge with three states and two high-side switches?

texts:
I want to drive a configuration similar to the one presented in Figure 1 of A novel tri-state boost converter with fast dynamics, but use a MOSFET instead of the diode for efficiency.

I want to put two in bridge, but the exact circuit is not important. Key features are that each side will have 3 switches, of which 2 are high-sides switches. Each side has 3 states, with dead time between states. Diodes are not an option for efficiency reasons.

So the question is how I can drive a PWM with 3 states with dead time, something like this:

Bridge driver IC only have 2 or 4 switches with two states.
So probably separate high-side and low-side gate drivers will be required.
But that leaves the problem of dead time.
Are there any PWM IC or MCU with PWM that can handle dead time between three states?


texts:
I am trying to construct a display that is shaped like an eighth piece of a sphere.
The resulting device shall be self-sufficient and possibly portable, meaning projection onto matte octant won't do it. The screen should be capable of displaying photorealistic images at a high frame rate, so POV display won't suffice as well.
Primarily, I see two options here:

to curve light output from a regular “planar” display with a lens or anyhow else,
or to give needed curvature to the display matrix itself.

Having thought over the first approach, I foresee two main concerns to deal with. The first one is that homogenous pixel density will become heterogenous when light is bent in non-isomorphic manner (see figure).

That is, to make a plane into a sphere, we need to stretch periphery more than centre, therefore pixel density will be affected likewise so we get fewer pixels to corners. This could be partially mitigated through software, but the problem still remains.
The second problem is the lens itself. I am not confident enough on the right branch of optics or optical engineering to be able to determine which type of optical device and of what metrics should be used here.

The second mentioned approach with already curved matrix seems less complicating, although I do not know how to produce such displays, or how to order them; and I am not sure about image quality of such displays, should they exist.

Thank you for your interest. Any suggestion would be much appreciated.


texts: MOSFET gets unusually hot in a SEPIC converter

texts:
I have constructed a SEPIC converter which is to be used for maximum power point tracking (MPPT). For simplicity, I am currently just using the hill climbing algorithm with fixed duty cycle steps of 0.01. The MPPT algorithm is implemented in the MSP430F5529 micro-controller and the PWM signal from the MSP430 is fed to a simple driver circuit for the MOSFET. The PWM signal has an ON voltage of 3.3 Volts which is what the MSP430 naturally outputs.

The following is the schematic of the SEPIC and driver circuit.

The input is a solar panel with:

V_oc = 6V
V_mp = 5V
I_sc = 0.67A
I_mp = 0.6A

Thus, the nominal output power should be around 3 Watts. The output is simply a 22 ohm resistor.

The FQP30N06L power MOSFET is currently being used on the switch and it is being switched at 50kHz. Now comes the main issue and the reason I am posting this question - During operation at duty cycles at around 0.35-0.5, the MOSFET gets unusually hot - At least 70 degrees celcius in a room temperature environment. On the other hand, I did measure the waveform of both the gate voltage V_GS and the switch voltage V_DS as shown in the figures below.

I did notice that the beginning of the pulses of the switch voltage V_DS has some unusually high peaks but I am not sure what these are. Perhaps someone could also point out why these peaks occur.

So what could possibly cause the MOSFET to become so hot and hence cause my converter to be very inefficient?


texts: trying to simulate pspice but there "Invalid value Circuit has errors ... run aborted See output file for details Simulation aborted"


texts: Boost converter: doubts on signs voltages

texts:
Please, if you could explain me why on step-up (boost) converter the sign of the t-off voltage part is positive in the following equation:

Vd * tOn + (Vd - Vo) * tOff = 0

I thought that the difference between (Vd - Vo) is positive (otherwise the diode would be off) and this justifies the above equation but if (Vd - Vo) is positive, the current in the inductor during the tOff period would increase and not decrease.

Thank you in advance.

Source: https://en.wikipedia.org/wiki/Boost_converter
Book: Mohan, Ned; Undeland, Tore M.; Robbins, William P. (2003). Power Electronics. Hoboken: John Wiley & Sons, Inc. ISBN 978-0-471-42908-1.


texts: MOV failed due to lighting or OV on power line Feeder control

texts:
we have a filed failure of our product which is feeder controller as shown in below image. It installed in metal box. we have tested our feeder stand alone at 15KV surge and it compliance with 15KV. But we also added one external SPD to get more surge protection. last month customer reported approx. 35 feeder burnet out in line. we have checked all feeder and found MOV2, Fuse and L1 all are burn. and MOV1 was fine. customer reported lightening happed in that area usually.

But I guess if this is because if lightening than we have protection till 15KV.
Q1) it should protect my feeder from failure. Why is not protecting ?
Q2) If Surge was above 15KAV than it should fail SPD first rather than Feeder. Right?
I guess there can be a temporary over voltage condition on line due to that MOV 2 and fuse got burnet. my Feeder is sealed pack unit, even I single component failed we need to to RMA and replace the unit. Is there any solution externally I can add like Over voltage cut off device (OVCD), I search on internet but couldn't find any reliable OVCD. Please advise


texts: Controlling LED Bulb Dimmer via Microcontroller

texts:
I have several (Cree LED bulbs) that I would like to dim via microcontroller. According to Cree the bulbs are dimmable with compatible dimmers. A local hardware store here in Canada has one of the listed dimmers in a convenient form factor (Lutron TTCL-100LH-WH-C). The dimming control in the particular product is a slider. The goal is to try to spoof the slider signal so it can be controlled remotely via microcontroller.

Does anyone have an experience how the dial controls of LED dimmers interface with the control circuitry? I'm hoping that the slider acts like a potentiometer and outputs a linear voltage to the control circuitry. This would mean that I can easily drive it with PWM + low pass filter or external DAC.

Hoping to get some feedback before cutting into one these modules. Has anyone done a teardown on these devices? Thanks.


texts: How can we understand portable battery for mobile phones having 10000 mAh capacity, and 6200 mAh "nameplate capacity"?

texts:
In USA, I always see portable batteries for mobile phone stating they have 5000 mAh, 10000 mAh, or 13000 mAh, etc. (One of the popular one is Anker as on Amazon.com).  However, in Asia, I saw the batteries having a spec of 10000 mAh "battery capacity", but a "nameplate capacity" of 6200 mAh. Another battery was 10000 mAh but its "nameplate capacity" was 5100 mAh.

The word for "nameplate capacity" is "額定容量" and it seemed to mean "effective capacity". It seemed 10000 mAh is relative to 3.6V of the internal batteries in the charger, and the effective capacity is relative to 5V. (and if it is for QC 2.0 or 3.0 and 9V charging, then the mAh drops to close to about half).

How can we understand this? Does that mean batteries like Anker stating 10000 mAh is also nominal and it really has an effective capacity that is not stated?


texts: What is the total propagation delay of the ripple adder?

texts:
Assume 4 full adders are cascaded.

Propagation delay of XOR gate = 20 ns, AND gate = 15 ns and OR gate = 10 ns.

What is the total propagation delay of the ripple adder, if the output is stabilized ?

My try :

When 4 full adders are cascaded, then carry has to ripple upto the last adder.

After the output is stabilized, I can say total propagation delay = 3*45 + 40 = 175 ns.

My try is based on the assumption of below circuits.

Here, 1st XOR and 1st AND gate can be done parallely and 2nd XOR and 2nd AND gate can be done parallely.


texts:
I need to design a circuit that generates the voltage waveform shown in the Figure 1 when an input voltage is applied as shown in Figure 2. Figure 1 and Figure 2 are in the second link below. Only Opamps and RC circuits are available and LTspice IV must be used. I am sophomore at electrical engineering and I was trying during the last 8 hours but I just get closed as in the first link below that contains the .asc file that I worked on and that you can work. I will be glad if you help me to complete the circuit.
https://www.dropbox.com/s/tbs3i1e6ckk1c09/Draft10.asc

Sincerely
Thank you who participated by answering this question. The given information is really helpful. I designed the circuit as given in the link below. https://www.dropbox.com/s/gl48itw82hu4l4v/Yeni%20Microsoft%20Office%20Word%20Belgesi.docx However, this design is still include too much staff. Can anyone design a better one and share to us?


texts: How to identify a faulty peripheral before connecting to my Beaglebone microcontroller? Board damaged connecting to ADXL345

texts:
I was trying to connect ADXL345 via SPI interfacing to beaglebone black via a breadboard. The board was purchased a month back and was all good when connected to others like mpu6050.

I suspect the ADXL345 device was faulty, and possibly got shorted when i tried to connect it to the board, but i can't confirm on it. The pic of my ADXL345 if you see, has one of the chips at the bottom right corner above Y is slightly bent, so i suspect it is faulty.

My question:

1) Before connecting an external peripheral, how do i ensure it has no shorts? What apparatus or instruments i use to confirm that?

2) What should be the sequence of connection to beaglebone? Do i connect ground and Vcc at the end? Should i connect them when the board is turned off? Should ground connect before Vcc?

Kindly suggest - i have just ended up damaging a new board.


texts: what kind of submeter in terms of amperage should I get

texts: I need to install a submeter for a tenant who has 3 chillers (610 watts @ 220 volts) and some LED lights only.  I see some submeters that are rated 30 amps and 60 amps? What submeter size should I get?


texts:
I am facing annoying issues when converting 24V AC to 12 V DC. I want run 30 W LED and I have a limitation in input that I can only use 24V AC output of a transformer. I have the circuit as shown, but the problem is that the LED doesn't glow much, it is getting 12v but I am not sure about the current and R1 (as in figure) heats up very much.

Please help me reach my goal.


texts:
Assume I have a pulse train with frequency of F Hertz. A normal square wave has all odd harmonics. From Nyquist,  if I want to "Reconstruct" the waveform, sampling frequency Fs should be at least 2*(2k+1)*F for some large k.

What if I don't want to reconstuct the waveform and just want to able to detect Highs and Lows? UART receivers for example, sample at 8 or 16 times the frequency F.
Is that because they just want to detect High and Lows? They don't want to actually reconstruct the waveform, are just interested in certain points.


texts: High AC voltage on Touch Sensitive Switch

texts:
I recently got a 120V/240V On/Off Touch Switch kit (ZIJIA P12-L56).   They are a cheap way of adding Touch Lamp functionality to a standard lamp.  It works great and I immediately started poking around inside it. While doing this I noticed that when I used my multimeter to measure the voltage between the touch switch and ground it read at ~99.8VAC.

That voltage differential seemed very large to me and definitely something I should feel when I touch the switch.

Why don't I feel a shock from a relatively high voltage?

I don't have a full diagram of the circuit inside but the Switch lead comes directly off the center pin of a Mosfet.


texts:
I am currently going through the MIT 6.002 lecture videos to help prepare me for my upcoming electronics final, and I came across something that I didn't quite understand

https://youtu.be/WT-qzgaKeGI?list=PL9F74AFA03AA06A11&t=2402

url point to the video and the point in time I am confused about

More specifically:

So far I have been understanding the general idea of how the low/high/band pass (and band stop) filters work, and how they can be created. I understood where he got the part of the graph at low frequencies because the inductor becomes a short, the voltage goes across that and very little drops across the capacitor where Vout is being read. What confused me is the next part, where he says at high frequencies the capacitor is a short, which i understood, but to me that meant the voltage drop happens across the capacitor now, not the inductor, and so Vout gets the voltage drop and you have a high pass filter.

I know from other videos, other classes, and the end of the video that the filter is a band pass, but I am having trouble building that intuition, so I was wondering if anyone here can help explain to me what happens to cause that band pass behavior

I could look at the transfer function, which Im sure will get me the answer, but Im really hoping to build up my intuition about these so I can go on and understand more complicated circuits. Thank you for any help!

As a side note: The way the MIT lectures have been teaching me to look at the circuits, and the way I have been from other classes, is that you look at what happens at low frequencies (capacitors go to open, inductors go to short) and high frequencies (the opposite) and see what happens at your Vout (where you are measuring). So far, I have gotten all of the series examples right, but this one is throwing me off. Am I missing something? Also, I keep thinking that voltage across parallel components is the same, which makes me think the 0 at high frequencies makes sense, yet since the voltage is always across at least one path, I expect it to be a band stop with purely that logic... I know Im missing some key logic here!


texts: Frequency of operation of typical laptop's 5V switching regulator powering USB ports

texts: What lowest frequency should I expect from a modern laptop? I need to calculate a filter for powering some analog circuitry from USB.


texts: Are there common circuit stability issues at low current levels and/or recommended minimum values?

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I'm building a small semi-permanent solderable PCB circuit using a couple of mosfet inverters, plus some resistors for voltage division and pulling inputs/outputs high/low. The final location will be inside the cabin of an off-road vehicle in the general vicinity of a 20 kWh 48 V DC battery bank which shares a common ground with the vehicle's 12 V DC electrical system.
My 12V breadboard prototype functions well, and I'm keeping power consumption low, so my currents are often in the 300-500 uA range. The 48V version will get as low as 20 uA in some places.
Is there a lower limit on current where pcb parasitic capacitance, signal interference, or any other issues begin to play a role?
Do circuit designers often keep amperage at some nominal level to avoid these issues?
Do those values vary with environment, and if so, what would be good for automotive (assuming inside the vehicle, not in the engine compartment)?


texts: Voltage and Current Stability in a Voltage Divider

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simulate this circuit – Schematic created using CircuitLab
The voltage divider is used in many circuits such as biasing the base of a transistor, etc.
Why is the voltage in the circuit on the left considered more stable than in the circuit on the right, if the voltage and current in the load is the same in both circuits?
EDIT: I have edited the circuit to clarify
My question refers to ..., if the load consumption changes, its resistance will change
So why is the voltage on the load more stable with a voltage divider than without a voltage divider?
Thank you


texts: The decimal value 0.5 in IEEE single precision floating point representation?

texts: If I hadn't studied floating point from here my answer would be fraction bits of 000…000 and exponent value of −1 as shown below :  But in the link I attached above, they mention Denormalized value in which case my answer for this question would be fraction bits of 100…000 and exponent value of 0. I know I'm mixing something up, and the second answer is probably wrong. Can somebody please clarify why it can't be denormalised value?


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I have designed an MCU-based PWM dimmer for LED strips.

My circuit works fine but there is a problem: The MOSFET is unexpectedly hot (i.e. 65°C). So I scoped the drain voltage using an oscilloscope and I saw that the drain voltage was about 0.130V (as expected) when the MOSFET is on, but it is 9V --it should be 16V-- when the MOSFET is off. So I'm not sure but I think that this causes the MOSFET to heat up.

simulate this circuit – Schematic created using CircuitLab

Where is my fault? How can I solve this problem?

EDIT: Here are the waveform of VDS:


texts: How to understand the schematic symbol of this isolated, filtered BNC connector?

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I found some isolated panel-mount BNC connectors which have an integrated capacitor for RF chassis-bonding, e.g. this molex part 73100-0090.
The datasheet contains this simple schematic to illustrate the connection of the terminals:

Obviously, the capacitor connects between the shell and the grounded parts (posts and compression clip).
But how is the pin electrode (A) connected in this scheme?
Image and 3-d view available here:
Kind regards.