texts: Signal speed through different materials

texts:
I've been tolled that signals are carried by electromagnetic waves caused by oscillating charges, and that this action occurs in a manner similar to how billiard balls interact with one another.

I'm wondering if its also similar to how sound waves travel through air. Taking this another step further, sound waves travel faster in dense cold air. Do electromagnetic signals travel faster through conducting wire than through air. Since I imagine the charged particles involved would be spaced more closely.


texts:
Please see images of question and solution. Please see my working out using the small-signal model

I'm really confused about how they went about solving the input impedance of this circuit? Did they use DC biasing or the small-signal model to work out the input impedance?


texts: I'm making a modest Tesla coil powered by an automobile ignition coil. All the instructables online say that I must also protect my home's 120 volt AC mains with an RF line filter. Trouble is, no one says what current or voltage rating these filters should be. So far, my guess is that a 120 volt, 10 amp AC filter should be acceptable. Can anyone confirm this?


texts: Teensy 3.0 Problems with moderate range (~40m) OneWire Signals

texts:
I'm using a Teensy 3.0 (with its 3V TTL signaling) to try and communicate with some Dallas DS18B20 temperature probes.

I'm not using parasitic power because I've heard a separate power line allows for more reliable longer connections. I'm powering this using the 5V Vin pin of my Teensy:

Communication is done using one of the 3V TTL pins (pin 14) with a 4.7k ohm pullup resistor to 5V (more on this below).

Using the standard OneWire example sketch in the Arduino IDE enables me to receive perfect temperature measurements with a short (d = 5m) cable, even with several temperature probes on the line. But when using a d = ~40m cable, the signal seems to drop out and no communication can be had (address detection fails, and even when hard-coding the device addresses into the code, the resulting read bits are all zeros (or the CRC check fails)).

I originally thought it was a cable that had too much capacitance (as I read about in some other threads) so I tried replacing it with an equally long cat5e ethernet cable (using solid orange, blue, and brown for the 5V, signal, and GND respectively) with a RJ45 tester to know that the cable is good. This had the same results as my previous cabling attempt.

So my question is: does anyone have any troubleshooting steps to try? I don't have an oscilloscope or logic analyzer unfortunately, and I've tried naively watching the signal voltages using my multimeter without much success.

One puzzling part about the whole thing is: If I'm powering the Dallas probes with 5V, and I have a 5V pullup to a 3V TTL pin on the Teensy, then how is this setup working at all? Perhaps the Teensy is able to pull the line down to ground successfully even though it is 3V ttl?

I tried powering the probes with 3.3V pin (2 pins under Vin), and connecting the pullup resistor to that, but then even the short length of cabling didn't work.

I've also tried using another 4.7k resistor in parallel with the pullup resistor to get it closer to 2k (which I've heard is good for longer runs), but this didn't have any effect.

Thanks for any help/suggestions/comments!

* UPDATE *

I have added a (possibly the world's worst) circuit diagram to make the situation more understandable. Sorry for not doing this from the beginning.

Also, one good resource that I have looked over is this application note which recommends Cat5e cable and mentions networks up to several hundred meters in length.


texts:
I'm trying to use USART in my program on STM32F205VC, but instead of sending my data I get some weird chars in PuTTY. I've used a Saleae Logical Analyzer and the result looks like this:

This is my full app code:

#include <stm32f2xx_gpio.h>
#include <stm32f2xx_rcc.h>
#include <stm32f2xx_usart.h>

#define USART_PORT GPIOB

#define USART_TX_PIN GPIO_Pin_6
#define USART_TX_PIN_SOURCE GPIO_PinSource6

#define USART_RX_PIN GPIO_Pin_7
#define USART_RX_PIN_SOURCE GPIO_PinSource7

void SetupLED(GPIO_TypeDef* port, uint32_t pin)
{
    GPIO_InitTypeDef GPIO_InitStructure;

    GPIO_InitStructure.GPIO_Pin = pin;

    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT;
    GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;

    GPIO_Init(port, &GPIO_InitStructure);
}

void SetupUSART()
{
    USART_InitTypeDef usartConfig;

    usartConfig.USART_BaudRate = 9600;
    usartConfig.USART_WordLength = USART_WordLength_8b;
    usartConfig.USART_StopBits = USART_StopBits_1;
    usartConfig.USART_Parity = USART_Parity_No;
    usartConfig.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
    usartConfig.USART_HardwareFlowControl = USART_HardwareFlowControl_None;

    USART_Cmd(USART1, ENABLE);
    USART_Init(USART1, &usartConfig);

    GPIO_InitTypeDef gpioConfig;

    gpioConfig.GPIO_Mode = GPIO_Mode_AF;
    gpioConfig.GPIO_Pin = USART_TX_PIN;
    gpioConfig.GPIO_Speed = GPIO_Speed_100MHz;
    GPIO_Init(USART_PORT, &gpioConfig);
    GPIO_PinAFConfig(USART_PORT, USART_TX_PIN_SOURCE, GPIO_AF_USART1);

    gpioConfig.GPIO_Mode = GPIO_Mode_AF;
    gpioConfig.GPIO_Pin = USART_RX_PIN;
    GPIO_Init(USART_PORT, &gpioConfig);
    GPIO_PinAFConfig(USART_PORT, USART_RX_PIN_SOURCE, GPIO_AF_USART1);
}

void USART_SendByteSync(USART_TypeDef *USARTx, char byte)
{
    while (USART_GetFlagStatus(USARTx, USART_FLAG_TXE) == RESET) { }
    USART_SendData(USARTx, byte);
    while (USART_GetFlagStatus(USARTx, USART_FLAG_TC) == RESET) { }
}

void StartClocks()
{
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA | RCC_AHB1Periph_GPIOB, ENABLE);
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);
}

int main()
{
    StartClocks();
    SetupUSART();

    SetupLED(GPIOA, GPIO_Pin_1 | GPIO_Pin_2 | GPIO_Pin_3);
    GPIO_SetBits(GPIOA, GPIO_Pin_1 | GPIO_Pin_3);

    while (true)
    {
        USART_SendByteSync(USART1, 'e');
        for (int i = 0; i < 1000000; i++)
            asm("nop");
    }
}


texts:
Below is a pi model schematic of a cascaded amplifier. The goal is to find the gain with Rp as load.

So the gain would be:
\$ A = \frac{V_{out}}{V_{in}}\$. So i set out to find \$V_{out}\$ in terms of \$V_{in}\$ as  \$V_{out}=i_{Rp}R_p=\frac{300}{500}\beta i_{b2}R_p \$

I believe the answer is very simple, but I can't seem to express \$i_{b2}\$ in terms of \$i_{b1}\$ and thus \$V_{in}\$ because of the current \$i_1\$.


texts: Nominal voltage of a battery with or without ESR?

texts: I am reading a calculation document which has calculated nominal voltage at MPV(50%) with the open circuit voltage from the datasheet, but from what I have read so far on different forums its the voltage which we should observe for most of the use of the battery at the terminals which means that the nominal voltage also includes the drop across the internal resistance and not just an OCV, is my assumption correct ?


texts: Trying to determine battery size with a TI BQ25504

texts:
Currently I am trying to design a low power tracker in order to track cattle. I would like to implement a solar panel to keep the circuit powered. Through my research I found the Texas Instruments BQ25504 that can monitor and store the collected energy. The issue I am having is what to use for a battery. In the data sheet it gives an equation for the equivalent capacitance of the battery needed: A storage element
with 100 uF equivalent capacitance is required to filter the pulse currents of the PFM switching charger Ceq = 100uF = 2 x mAHr(Bat) x 3600 s/Hr / V(Bat)  After simplifying the equation I got:  (1F/72,000) = (X Amp Seconds)/V(Bat) So to me this says in order to have a voltage of 4.2V I would need a .085mA battery. To me that seems off in some way but I don't know if it was my math or does this BQ25504 indeed only allow very small batteries?


texts: Calculating the frequency of CPM signal in System Generator

texts:
I have a circuit which has been designed by System Generator to be implemented on FPGA. The circuit's output is a CPM (Continuous Phase Modulation) signal in which it is apparent that its instantaneous frequency is changeable. I should transmit the data via UART and RS232 to see it on a computer.

However, it has the problem that, in high frequencies, the Nyquist criterion has been violated and hence in high frequency I have not a nice sinusoidal signal. I think that for resolving this issue I should relate the start of UART to the frequency of output signal. Now I wonder:

How should I measure the instantaneous frequency of CPM signal?
In other words, how should I measure it in System Generator?


texts:
This is probably an elementary question, but I wanted to be sure.

I have a system that reads instantaneous watts values, and stores them as "events", with a power value and a time value.

According to the answer here (Should I multiply by time to determine Watt-hours?) it's simply an "take an average of the power readings, then multiply by time" to get it. That's the crude version, then calculus is mentioned.

Unfortunately, most of my calc has left me behind, and I'm not sure what type of integration to do over a set of points that doesn't really have any rhyme or reason (ie, f(x) is not just x^2, it's kind of all over the place).

Is the integration version that much more accurate? If I were trying to calculate the kWh over time for my house, and match it as close as possible to what the power company bills me for at the end of the month, what would be best? Is the average * time good enough?

FWIW, I'm in python, and looking at http://docs.scipy.org/doc/scipy/reference/tutorial/integrate.html . I'm assuming (again, calc was quite a while ago) that I'd use the trapz version, since the others appear to need a function, and trapz (and simps?) appear to work on sample-style data.

Thanks very much for any help!


texts: Can I use a TVS diode to remove spikes in SMPS?

texts:
I have an almost working Half-Bridge SMPS that has some ringing in the output like this (not the real output, just and image I found):

I have eliminated almost all the oscillation using a snubber network on the secondary side (C=2.2nF and R=15 Ohm). The problem is that this spikes are still there and this is translated to the rectified output. If I increase the value of the capacitor in the snubber this spikes gets lower but the dissipated power in the resistor increases a lot (a 3W resistor just burns instantly with a 10nF capacitor).

The square wave has a max value of about 50V and this spikes are about 90V. I though in adding a TVS diode in series to the capacitor and the resistor in the snubber network with a breakdown voltage of around 50V to remove this spikes. Is this feasible? Or would it be better to just add a bigger capacitor value with a bigger resistor?

EDIT:

This is the output stage:

D6 is a MUR3060, R15 is 3W metalfin, C17 and C18 are low ESR capacitors.

edit: I'm probing with this:

edit: My circuit is a half-bridge SMPS like this:


texts: How do you represent a SOP in terms of NAND?

texts:
Is there a specific technique to convert SOPs to NAND.

I have the following expression:

A'BC + ABC'

And would like to represent it using only NAND gates.

A'BC=(((AB')')'C')'

ABC'=(((A'B')')'C')'

But now, how can you represent the or part using NAND gate?


texts: FIR Filter delay calculation for cascaded filters

texts:
I have created a simulink model which had two filters implemented with an FIR block cascaded in series.
The first filter in my case is a moving average filter and the second one a Gaussian filter(being a special case of an FIR filter), which would obviously generate a delay ,Now my confusion is for the amount of delay it will produce.  For symmetric coefficients for a single FIR  filter it is (number of co-effcients)/2 but for a cascaded form would it be the (number of coeffcients of filter1 + number of coeffcients of filter2) /2 or (number of coeffcients)/2 +1 as there is one sample delay between both the filters assuming that the number of coefficients of both the filters are the same


texts: Circuit to supply power to USB during car brownout

texts:
I have a USB car charger plugged in the accessory port of my car and I also have a simple bluetooth USB to aux adapter plugged into it. As I start the car, the power drops to the accessory port and the adapter's bluetooth connection disconnects from my phone. It's annoying having to wait for it to reconnect and start my music every time, plus its illegal to operate a phone here in the UK.

I want to know if I could create a simple circuit to hold enough power to keep the adapter running while the power drops. I think the power drop lasts roughly 5-10 seconds and the bluetooth adapter is only 5v 0.1a. Could a capacitor help in this situation?


texts:
I'm trying to figure out the voltage and current (and subsequently power) of the resistor R2 in this circuit:

simulate this circuit – Schematic created using CircuitLab

The circuit is in resonance and the inductors are lined with a coupling coefficient of 0,9.

From my understanding of mutual inductance I get the following KVL equations:
$$ -V_{in} R_1 I_1 + (j\omega L -j\omega L)I_1 + j\omega kLnI_2 = 0 $$
$$ R_2 I_1 + j\omega L n^2 I_2 + j\omega kLnI_1 = 0 $$

Solving for I2 I get:
$$ I_2 = \frac{-j\omega kLn V_{in}}{R_2 + \frac{\omega^2k^2L^2n^2}{R_1} + j\omega Ln^2 } $$

However when I compare this to simulations in LTspice (with a timestep of 0.1ns) it differs quite a lot (with around 10% if not more), so I am very unsure if this is correct.
I have taken the absolute value of I2 as the amplitude of the wave.
Does anyone know what is wrong here? Or are simulation programs not exact? :S


texts: 555 trigger amplitude slightly too large to trigger

texts:
I have the following circuit which is designed to take a longer pulse (on the order of miliseconds) from a microcontroller (source v3 below) and use two 555 timers in cascade to output two consecutive smaller width pulses (ranging from 0.5us to 10us and individually adjustable through a pot [not shown in the schematic below]). These two consecutive pulses are triggered from this longer pulse. The output pulse from the second 555 timer should follow after, when the output from the first timer goes low. I've used RC differentiators between the first BJT inverter and between the two 555 timers to avoid multiple triggering of the timers.

The simulated circuit below shows from top to bottom the input pulse, the output after the BJT inverter, the output after the first edge detector (555 trigger input number 1), the output of the first 555 timer, the output after the second edge detector (555 trigger input 2) and the second 555 timer output.

I've built this circuit and the output of the first 555 timer produces a satisfactory pulse however the input to the trigger of the second 555 timer with edge detection reaches a value just short of the 1/3VCC value required to trigger the second timer. In simulation it dips below this 1/3VCC value and the second 555 timer triggers correctly however in practice this does not happen as shown in the oscilliscope reading below. The lowest value it reaches is 2V.
Oscilliscope measurement at the input to the second 555 timer. (node titled in1 in the schematic above)

I have tried adjusting C4 and R9 (edge detector time constant) to get this value lower but it affects only the discharge rate rather than the amplitude. Connecting the top of the second edge detector to a lower voltage such as 3v rather than 5v results in a lower trigger value however I don't want to use a seperate lower source to solve this. I'm looking for a simple way to drop this trigger voltage by 500mV or so, so that the second timer will trigger.
edit

I'm actually using an NE556 IC instead of two NE555s.
The outputs of the 555 timers go into unity gain buffers with an op-amp.


texts:
I want to send data, C# to PIC by using USB (UsbLibrary.dll).
I am using below codes for sending data;

private void button1_Click(object sender, EventArgs e)
        {
            byte[] my_buffer = new byte[64];
            my_buffer[1] = (byte)0x01;
            usbHidPort1.SpecifiedDevice.SendData(my_buffer);
        }

But I got error as usbHidPort1.SpecifiedDevice value is null (which means that Connected PIC Device is not identified by C#) although vendor and product id coded same in C# and CCS C (PIC). How can send data C# to PIC by using UsbLibrary?


texts:
(using KiCad 4.05 at the moment)

I’ve been following video and blog instructions on how to create a PCB.

Everything has been straightforward (have used EAGLE a bit many years ago) up until ‘add filled zones.’

I’ve also performed ‘DRC control,’ to no avail.

It seems when i select ‘no net,’ it does color the bounded area.

Help would be much appreciated. Thanks

(unlike what’s selected in the image, I chose GND, if it is relevant)


texts: import PCB components into KiCAD which are sold in the electronics industry

texts: When drawing a schematic in Eeschema Editor in KiCAD, there is a button to "Run CvPcb to associate components and footprints", so a schematic symbol on the *.sch file can be associated to a physical component to generate the Netlist and be soldered on the PCB when manufacturered.  The component list in this library is kind of small relative to the number of components available for sale online.  Is it possible to import components into KiCAD that users of the program have already created, so you don't have to build them from scratch using the Editor?  Where can I find them, and how do I import them?  I've only been using KiCAD for a week, because I learned it in Ham Radio Club.  So I've never drawn a schematic before this week.


texts:
Scenario:

I've disassembled this USB camera and I had to cut a wire. I'd like a small male / female connector pair to put it back together.

Frayed wire (right) is connected to the black plug (right/bottom) in the second photo. I would like to know the name of this male + female / polarized connector. This connects to a USB 3 plug.
White plug (left) is connected to the white plug (left/top) in the second photo. I don't need to replace this but I would still like to know what it's called. This connects to a servo motor.

Extra:

On the frayed wire it's using a two row (2x3) connector but there are only 5 wires. I assume the 6th wire is the protective wrap around the outside of the wires?


texts: Can we get more current by reducing voltage on a power supply?

texts:
This is very basic question but I seem can't find the answer. All out there is theory, but no practical explanation about this.

Assume I have a 10V 2A power supply. So in theory it outputs power of 20 watts. Now if I reduce the voltage to 5V with a 5A capable buck converter, can it output the same 20 watts? If so, 5V will use 4A to achieve that.

In general, can we increase the current by reducing the voltage in a power supply?


texts: Resistor for high power but low energy (pulsed operation)

texts:
I need to make a pi attenuator which must support voltages of about 100 V and 20A but only on a pulse of 250ns.

But I do not know what resistor to use because it creates a power of about 2kW but only 500uJ.

All the power resistors that I see are sized according to the power and not the energy so I do not know how to choose.


texts:
I am using attiny85 to control 4 motors that work all togather at the same time.
Will that hurt the attiny85 controller or is it ok. Because I think that the 4 motors will draw high power through the attiny85 and that may affect it.
So should I use relay at this situation?


texts: Multiple (independent) circuits on the same PCB in Multisim/Ultiboard

texts:
I have designed and simulated a few circuits on Multisim. Usually, I order a PCB for the layout of each circuit independently. However, it is cost-effective to put multiple circuits on the same board (the cost of an additional circuit on the same board is less than the cost of a new board with the additional circuit).

How does one put together multiple independent layouts from different circuits on the same PCB in Ultiboard? Several issues arise if one simply draws all the circuits in one schematic and puts them together on the same board -- for example ground and power planes get shared, and I do not want this.


texts: Best way to isolate RF Coupling (2,4 GHz - 2,5 GHz)

texts:
I bought an ADF4350 PLL board from china. On the board there are 10 pins (programming and supply) which are connected to my BLE board (with an integrated antenna).

Im observing following problem:

When the PLL board is connected and output a signal (let's say 2.48 GHz, and not to the BLE board), my BLE board has a much worse sensitivity at this frequency. The 10 pins on the PLL board are connected over a ribbon cable with the BLE Board. When I put the cable on a ferrite ( unfortunatly I don't know what kind of ferrite it is) the sensitivity gets better but still not as good as without the connection to the PLL board.

Now my question:

Are there any types of ferrites which will have a high enough impedance at this frequency range to prevent this?

Or is there a better possibility to fix this?

Best regards


texts: How to automotive/boat devices limit voltage to 12 volts?

texts:
I live on a boat and get all my electricity from 12 volt battery arrays.  The batteries are charged using either 1) alternator on the diesel engine or 2) charger/ inverter powered from shore power at a dock or a portable generator.  Yeah, some 120v power while on a dock or running the generator but not usually.

Most everything onboard is powered 12 volt DC, but in reality it's actually fluctuating from 12.4v to 14.6v. So how do electronics like chart plotters, SSB radio, am/fm car radio tolerate these changes?  Obviously they do it, and hopefully efficiently.

Is there a simple device to do this?

So far all I could find is " consider a simple PWM driver with mosfets controlled by a microcontroller, and figure out the correct pwm voltage correction empirically and be done with it. " which sounds interesting but doesn't do it for me.


texts: I'm planning to make a micro/nano quadcopter and I've bought all major components so far. The only thing that I can't figure out are motor drivers. I was planning to use some kind of transistor to do that for me (motors are 3.7V @ 1.5A marked). So I was wondering if that is a good idea? No commercial drivers can fit since it needs to be lightweight and I have 4 motors that need to be driven separately.


texts: Why are red LEDs so dim & how do I make them brighter?

texts:
Background
I am an electronics novice/hobbyist who is recently using an Arduino connected to a breadboard to prototype a set of navigation lights for a remote controlled hexacopter that I am building.
Similar to nav lights on airplanes, I have four strobing white lights that go on the tips of the back four rotor arms, and this alternates with strobing orange lights (beacon) on the top center and bottom center of the craft.  This is all fine.
In addition to the strobing lights, I have two solid green lights to go on the two right rear rotor arm tips, and two solid red LED lights to go on the left rear rotor arm tips.  All of this is fine too, but the red LEDs are really dim.
Question
No mater if I run the red LEDs through a battery or the Arduino, with a resistor or without and no matter the brand or MCD rating of the LED, they are always more dim than their counterparts of other colors.  How do I brighten the darn red LEDs?
Update
Here are the specs for the LEDs.  I got them off of eBay from a Chinese manufacturer.  There is not a brand name, but all are from the same source:
Emitted color: red, blue, green, yellow, white
20pcs for one color
Size: 5mm
Forward voltage: 1.9 - 3.6V DC
Luminous intensity: 500-20000 mcd


texts: What is the role of shunt in a Power Meter?

texts:
I just got a PZEM-051 Power meter and I can see that in order to measure the power, one needs a shunt. At least that's what I can see from different YouTube videos and I was wondering why would I need one? By looking at the scheme on the back of the meter, I can see that it has a shunt integrated (please see picture).

Do I understand the scheme wrong? What would be the role of the shunt and do I need one to read the power and the voltage from a power supply and a small pump?


texts: Arduino Pro Mini newbie question power supply

texts:
I am extremely fresh with this stuff (just started tinkering with my first project last week and fried one Arduino already)

Question 1:

I am basically supplying power to the Arduino from the back of my car's rear view mirror. The car's rear view mirror has 12v + ground out. I hooked that up to the Arduino RAW + GND and it fried right away! Reading the docs and MANY other posts before trying this, the RAW pin can take up to 12V and uses the built-in 5V regulator. Apparently, not in my case! What did I do wrong?

Question 2

I basically need to power 2 servos and trying to not splice any wires. If I use the car's back view mirror to a 5v regulator then to the Arduino, can I hook up to the RAW still and use the other two VCC pins to supply power to 2 servos? I know the bottom VCC in the picture below does power out, but not sure about the VCC on the right if it outputs power too or is just an intake to power the Arduino itself.

If I have regulated 12v to 5v source, can I still connect that to RAW?


texts:
I need to expand Arduino Uno output.
After some search I have identified 74HC595 to extend my Digital output and TLC5940 for analog output.

I'have also found how to connect them separately to Arduino Uno:

This two setups share some pins, I've seen in this thread that other people use them together but I'm not sure how to connect them to my Arduino. Can you give me a hint?

Libraries are also compatible?


texts: Can I read a Load Cell value from Electric Imp?

texts:
I would like to connect a Load Cell to an Electric Imp and read the weight's value.

I have found quite a few of tutorials where a temperature sensor is attached to the Electric Imp (see: https://www.youtube.com/watch?v=_Z6UdGik3z0) but for some reason when I see examples with Load Cell it seems that I have to use:

A load cell
A load cell amplifier (for example: XH711 - Sparkfun - Load Cell Amplifier)
A board (for example: Arduino mini pro - Sparkfun - Arduino Pro Mini)

My question is, can I just connect a load cell (or maybe a load cell amplifier) directly to the Electric Imp and read the value from there?


texts: Type K thermocouple durability in semimolten plastic

texts:
I want to measure the temperature of a semi-molten piece of plastic, but for my final application I don't want to have to touch the thermocouple.  This means it will more than likely end up in the hot plastic and will be stuck there once cooled.  I will heat the plastic again to remove the thermocouple.

Will a type K glass braided thermocouple withstand any necessary scraping of plastic off of it after I remove it and still provide accurate results?  I'm not very familiar with the sensitivity of the tips.


texts: Error in powergui block in Simulink involving vector dimensions.

texts:
I am designing a DC machine in Simscape, but when I try to run the simulation there is this weird error:

"Error in port widths or dimensions. Input port 2 of 'simulacaodcmono/powergui/EquivalentModel1/State-Space' is a one dimensional vector with 2 elements."

It's something internal to the powergui block, but that is how far as I could get... I am using Matlab 2013a. My friend tested the same file with a newer version of Matlab and got an error related to the Demux block.

This is my system:


texts:
I am working on a hobby project which will have a eTape Liquid Level sensor connected to an Arduino controller. Since it is highly inconvenient to attach the sensor directly to the board, I'm trying to find the best way to connect it via an extension wire. So far, I've been considering the 4-pin JST SM Receptacle Cable. The sensor comes with a small connector . What would be the best (i.e. clean and safe) way to attach this connector to the wire and have all wires isolated?

Alternatively, is there a better way to indirectly attach such sensors to a board?


texts: What is the significance of FO4 inverters in CMOS static circuits?

texts:
With regards to the image above, I wanted to know what is the importance of Fan Out of 4 (FO4) for optimum design and what improvements does it incur over designs that are either higher or lower than fan out of 4?

Also, with respect to the picture, what are the issues seen in circuits 1 ,2 and 4 as compared to circuit 3 with N=3, F=4, TP=15?

N = number of stages
F = fan out
TP = propagation delay


texts:
I've been making some research on DC motor drivers and I noticed that most medium power boards don't use inductors, but boards that can provide high current do, like this one:

https://www.cytron.io/p-60amp-7v-45v-smartdrive-dc-motor-driver-2-channels

What is the inductor used for in motor drivers?


texts: Help with identifying a transfer function - with neuroscience application

texts:
This is a question for you electrical network engineers. The problem has arisen in a neuroscience study I am working on, but I hope to be able to glean some insight from other domains that deal with electrical systems and control networks. The brain is an electrical system after all, so I figure it should be governed by similar processes to large-scale electrical closed loops systems (like power grids for example).

I have devised a transfer function, which I am using to investigate human brain networks. We have recorded electrical signals from region A in the brain and mapped them, via this transfer function, to region B.

The transfer function works as follows.

Take a recorded time series x which describes the time evolution of
some brain process.
Apply Fourier transform to get X
Apply a constant phase shift to all components of X to give Y, taking
care of the symmetry in the frequency domain (e.g. this could be a 90
deg phase shift).
Apply the inverse Fourier transform to Y to retrieve the time-shifted
signal y

The upshot of this is that lower frequencies are shifted in time MORE than higher frequencies. This appears to fit our brain data very well - which is something of a mystery. We don't actually understand why this works so well, so finding analogous systems in engineering would be a great help.

Therefore, my question is whether any of you can identify the type of transfer function we are using here. Does it have a proper name in engineering, is there a theoretical basis for it? The best I have come up with is that it is a minimum phase transfer function, but I don't yet understand how that might apply to a close loop system.

Even if someone could point me to the relevant textbook, that would also be very helpful.


texts:
I am currently looking at the datasheet of a LED and have snipped out the passage of interest.

The question is how do I find out the intensity I can reach at a specific temperature/current by using the these curves?

Assuming I have an high ambient temperature of let´say 80°C, the current derating curve (current versus Temperature) would tell that I can´t drive the LED with more than approximately 8mA.

Looking at the Intensity versus current, I can see that at 8mA, I can expect about 0.4 of relative Intensity. Fine so far.

Now what about the relative intensity via temperature curve? Do I have to consider the effect described in this curve separately to the derating done so far? Means at 80°C, I only have 0.5 of relative intensity, so I had 0.4 before, so combining would lead to 0.4*0.5 = 0.2 of relative intensity at 80°C and 8mA.

That seems really low. Is the interpretation I have described correct or did I considere some effect(s) twice?


texts: PIR sensor triggering randomly when connected to an esp8266

texts:
I've several of PIR sensor modules (HC-SR501) which are designed for a 5v input. However, I need it to run on a 3.3V system only. To achieve this, I removed the diode which is in series with the input power and a 7133 LDO. I then connected the output of the 7133 directly to the VIN pin.
As far as I understand, due removing this, there is no filtering of the input power. Which results in weird behavior, like triggering randomly all the time. This might be the ESP8266 which is generating noise when having the radio module active.
What would be a good way to remove this noise from the VIN of the PIR module? I tried placing a 0.1uf and 10uf ceramic capacitor close to the input pins, which didn't result in better behavior.
This is the circuit of the PIR module:

-- edit
I did read this on the product page:

"The module does not take the load to work properly, connected to the load after the work of chaos, one reason is because the power capacity is very small load power consumption, load caused by voltage fluctuations caused by the module malfunction, the other reason is the load The power will have interference in the work, such as relays or electromagnets and another inductive load will produce a reverse electromotive force, 315M emission plate will have electromagnetic radiation and other work will affect the module. The solution is as follows: A, the power part of the inductor filter. B, using the load and the module using different voltage methods, such as: load using 24V operating voltage, the module uses 12V operating voltage, during which the use of three-terminal regulator isolation. C: Use a larger capacity power supply."

What kinds of inductor would help?


texts: Why is transformer coupling used in a simple slope detector? Can't the FM signal be applied directly in parallel to a tuned circuit?

texts:
This is what I mean by simple slope detector:

Why can't it be like:


texts: For a vehicle, what is the most efficient way to store energy from various inputs?

texts:
Background
For the past few years I have wanted to make some sort of recreational vehicle that runs on multiple-source renewable energy.  For example, a kayak with a trolling motor that gets its electricity from pedal power and solar power.
I am no electrical engineer, but I imagine that one would need some configuration that converts the generated input from the pedals and solar panels to a correct voltage that can be accepted by a common battery that in turn runs the electric trolling motor.
Recently, however, I have read about fuel cells and I am wondering if it wouldn't be a more simple design to power the trolling motor with fuel cells and then use the solar and pedal energy to make the hydrogen from water.  It seems to me that this would avoid the need to convert the electricity coming from pedals and solar cells to any common factor.
Question
What is the most efficient way (in terms of cost, complexity and safety) to collect and store energy from multiple inputs for a recreational vehicle?
Please don't be limited to the above example electrical inputs.  For example, when the kayak is stationary, a raft with a solar collector and stirling engine could be deployed which takes advantage of the difference in temperature of the cold water beneath and the heated water above to provide a third source of electrical input.
Deploying a propeller like the one at this link could also be used as a sail/turbine.
Open Source
Once designed, this entire project will be open source.  Please let me know if you would like to be a part of that.


texts:
I'm trying to make a design where the user can run his/her finger directly over a series of 10 LEDs (covered with 1 mm glass), and the LEDs should glow on/off based on the finger's position.

I wish to use capacitive touch (like on a phone, where the touchscreen is directly above the LCD) to accomplish sensing of the user's finger.

I am familiar with making copper pads on a standard PCB to make a capacitive touch sensor, but if this opaque PCB goes on top of the LEDs, then their light would be obscured.

Is there some alternative strategy I can try in order to let the LED light come through and still allow capacitive touch sensing of the user's finger directly above the LEDs?

EDIT: Perhaps below design should work? (incorporating reverse-mount LED suggestion of user @Some Hardware Guy)

Green = PCB; Brown = Copper pads (for capacitive-sense), and Yellow = Reverse-mounted LEDs


texts: Can you run wires to an inductive heating coil or will that be a bad idea and why?

texts: I have an inductive heating circuit that runs at around 5A at 24V (I'm estimating here).  Is it possible to place the inductive heating coil a distance away from the circuit and connect the circuit to the coil via very high-current copper wires, or will intermediate objects made of metal that are close to the wires also inductively heat up?


texts:
Context:
I've built a robotic arm using servo motors, and have been having an issue with powering my servos.  The servos are all rated for 3A/6V, and I've been powering it with a modified computer power supply that is capable of outputting 17A at 5.2V. For the most part, the arm works beautifully with this power supply, and the lower voltage doesn't seem to affect its performance, except in the special case I will note below.

Problem:
When the arm is at full extension, and the servos are really exerting themselves, they sometimes make very quick movements, which causes them to draw more current than their 3A rating.  In essence, there are current spikes, and these spikes are tripping a switch in my power supply, which shuts it off.

Idea for Solution:
To correct this problem, I'd like to keep the same power supply, but introduce a capacitor bank that can provide a charge/current reservoir to the servos in case they need an extra boost.  I'm not sure if this is a good idea, or if there is anything I need to consider before pursuing this option.  If anyone has any advice or helpful resources, I would be very appreciative.

Thank you!


texts: I didn't jump on Netduino when I should have now it looks like they are in a very limited supply. Does any one know if there is going to be any more manufactured or possibly the beta Netduino?


texts:
I was watching one of Razavi's videos

https://youtu.be/pK2elUcXWzs?list=PLiDoPUX9nLkIw9EnIv_3K19wlcyJ6msYd&t=2309
Skip to 38:30

He did this:

He justified this approximation by saying that gm1ro1 and gm1ro2 >> 1. But how does that get rid of the extra +ro1 at the end?? Why is it not there in the end?


texts: Node voltages in the first-order op-amp circuit

texts:
Here is a first-order op-amp circuit:

I have to find V0 given that V(0) = 4 V (i.e. the capacitor is charged). If the capacitor is charged, then the voltage at the node 1 is V1 = 4V and KCL must look something like this:
$$
    \frac{0 - V_1}{R_1} = C\frac{dV}{dT} + \frac{V_1 - V_0}{R_f}
$$
However, the solution postulates that since the node 2 has a zero voltage, then V1 = 0. It seems that there is some contradiction. Does the voltage on the capacitor influences the voltage of the node 1 or not? I have studied op-amp theory, however, I feel perplexed because university curriculum and textbooks takes onto consideration only two cases: either the voltage source is between the ground and the inverting input or it is between the ground and the non-inverting input. This is the first time when I see such a circuit that's why I have posted this question.


texts:
My understanding is that unused outlets do not consume electricity, but I came across a company which sells outlet covers saying:

  Saves energy by helping reduce drafts through vacant receptacle
  outlets

I can't believe they are referring to "air drafts" as this seems such a ludicrous explanation (the outlet holes are so small and they are wired which makes the volume of air going through neglectable) that I'm wondering whether they are referring to electrical drafts which I wouldn't be aware of, hence why I'm seeking confirmation.

Do unused outlets consume electricity?


texts: Why should small capacitors be placed far away from the 'output' pin on a medium-sized LDO?

texts:
Reading the datasheet for an AZ1117E adjustable LDO voltage regulator capable of supplying 1A, I noticed the following recommendation, which I don't understand:

  "Close to the OUTPUT pin, it is not recommended to use a capacitor
  smaller than 0.68μF in parallel with output capacitor. When the output
  capacitor parallels 0.1μF capacitor, the 0.1μF capacitor must be away
  from the OUTPUT pin, the distance is no less than 5mm."

What is the reasoning behind that recommendation? Are they concerned about inrush current through a small ceramic capacitor with very low ESR or something like that? I can see why larger 1μF+ capacitors are needed on the input/output, but I don't get why smaller ones should be kept far away from the part.

I'm not sure if the current draw is actually relevant to this question or I'm simply unobservant, but I haven't noticed similar recommendations in other voltage regulators' datasheets.

Thanks!


texts:
What represents this formula in terms of an RLC series circuit that forms a resonator? It is called figure of merit and it is defined like this:

M = 1/ w*C1*R1

where w = 2*pi*f


texts: help figuring out how to replace/repair this component

texts:
The micro-USB jack in this board is broken and I was trying to figure out how to replace this entire thing. The micro-USB is for power/charging and the bigger USB has unknown functionality that we've never used.

As far as I can tell, this takes power from the micro-USB into a ribbon cable that plugs into the actual mainboard. plus whatever the USB-A does (output ?).

My goal is just to replace the power supply. However, it is impossibly hard to google and find any off-the-shelf component like this.

Anyone have any suggestions ? I am fine with wiring up a completely different USB power jack to this or the mainboard.


texts: How does using negative feedback in biasing stabilize the beta of a BJT?

texts:
As far as I know the only reason beta is not reliable because it is temperature dependent.

I have seen some diagrams about biasing to obtain stable beta. I read the negative feedback provides this but by looking at these biasing circuits I don understand how it happens logically.


texts:
I'm currently working on device that uses always-on 3D accelerometer(using scale +-2g) and 3D gyroscope(using scale +-250g) -sensor.

I can read every possible vector (X,Y,Z) and their acceleration (g's) and angular rate (dps) and also the angle where the device currently is. But my problem is that when the device is on tilt (0g when no tilt) the acceleration is between (downward) 0g->-1g or between (upwards) 0g-> 1g depending on what angle the device currently is. Below is picture that hopefully clears the idea.

The device will located in a car and should measure acceleration when car is slowing down (brake) . However if the device is already on tilt the accelerometer will measure some acceleration that tilt causes which makes it hard to tell if the device has truly some acceleration or is it just the tilt that causing the acceleration.

X and Y -Axis produce 0g and the Z axis is 1g when device has no tilt and is on flat surface. The tilt causes the reading of X axis to go towards 1g if tilting is towards up and to -1g when downwards. The +-1g is reached when the device is on 90* degree from original position

I have been thinking my head off how to eliminate that acceleration that tilt causes and only measure the real acceleration of the device but just can't think way out from this problem with the following data that i can produce.

Basically i think that if i could only measure the X axis acceleration (picture) even if the sensor is in tilt like in picture.

Hopefully this message isn't too hard too understand because of my english skills and the way I'm trying to explain my problem.


texts: Why wont Micro USB Hub work with UVC Receiver?

texts:
I want to charge my phone and be able to receive wireless signal via a UVC Receiver. So I ordered a Micro USB Hub Adapter that supports OTG and charging. Well, I tested the hub adapter today, but the UVC receiver does not detect my transmitter when it's plugged in to the adapter.

This is the hub adapter i ordered: Micro USB HUB Adaptor with Power, TUSITA 3-Port Charging OTG Host Cable Cord Adapter

And this is the UVC Receiver: FPV Receiver, EACHINE ROTG01 UVC OTG 5.8G 150CH Full Channel FPV Receiver for Android Mobile Phone Tablet Smartphone

When the UVC Receiver is plugged directly into the phone via the Micro USB port, the app I use to stream my camera feed reads "USB_DEVICE_ATTACHED" and then I can select the USB Web Camera to stream the feed. However, I don't see that message when plugged in through the hub. The First Person View (FPV) app I am using is called Go FPV.

Should a Micro USB Hub Adapter be able to support a UVC Receiver ? If so, it is a bug inside the Go FPV app? Your thoughts are appreciated.


texts: Controlling a Link Sprite camera through an AVR - how to get the data to a PC?

texts:
I have a Link Sprite camera through which I intend to take image captures and store them into an EEPROM. Later, I want to extract the data from the EEPROM and display the image on a PC. What are my options here?

I imagine UART is required to transmit the data to the PC, but what measures need to be taken on a PC to correctly extract this information? Are there any programs that allow you to send and save arbitrary bytes of data sent over USB?

I have purchased a UART to USB serial converter for this purpose, but am a but lost on where to begin with the associated computer program.


texts: Daisy-chain SPI modules current consideration

texts:
I'm using an Arduino due (3.3V) to drive some daisy-chained SPI DAC's (mcp4822).
I use only three cables a MOSI, SCK, and CS (chip select).
I'm using just one SPI channel and I select the active module with the CS signal.

The pins of Arduino are capable to deliver "3 mA or 15 mA, depending on the pin, or receive (sink) a current of 6 mA or 9 mA, depending on the pin".
Maximum current consumption for all pins connected to the micro-controller 150mA.

The MCP4822 "absolute maximum rating"
Current at Input Pins ±2mA
Current at Supply Pins ±50mA
Current at Output Pins ±25mA

Input-current: 415 (typical) 750 (maximum) μA

So my question is when daisy chaining modules does the current draw raises and if I connect around 6 modules will it damage the pins (I mean the MOSI and the SCK pins )?

Are the SPI pins of Arduino Due connected directly to the microprocessor, or is it a peripheral?

If that is the case should I use a resistor to limit the current?

And one last: if 6 modules would work ok, can I expect the same when connecting 15 or 30 modules (I mean in this fashion i.e. a MOSI and SCK that is connected serially to all modules and only different CS connections to each one).


texts: Does USB-C Alternate Mode require the Billboard Device to be always connected?

texts:
I'm working on a device design that operates in USB-C alternate mode as a displayport dongle.  As such it requires a USB 2.0 billboard device to be present to negotiate with the host and enter alt mode.

This might be a silly question but if after the device enters alt mode, I want to turn the USB 2.0 connection over to another device (using a USB Mux), can I disconnect the billboard and then point to my other USB device without losing Alt Mode function?  Or will alt mode cease function when the Billboard is disconnected?

In the USB-C Spec from August 2019, the following is stated

E.4.3 Operational Summary:

Host stays in USB DisplayPort Dock mode until

a. Explicitly exited by and Exit Mode VDM.

b. System physically disconnected from the USB DisplayPort Dock

c. Hard Reset on USB PD

d. VBus is removed

Would (b) count as physical device removal?  Or is it referring to the USB-C connection and not the USB 2.0 Billboard Interface?

Thanks for the help!


texts: Switching a Kettle On/Off using a arduino

texts:
First of I have no experience with electronics so I am not sure what I should be searching for to get this done.

All I have with me at the moment is a arduino and a few connectors and LED's. Is it possible to switch the kettle on/off using just these basics (i.e. I dont want to buy more stuff for now).

The kettle is the most basic kind , i.e. the ones that plug into a wall outlet and have a single switch to turn it on or off. Let me know if you need more info.


texts:
Since I've always did electronics through my Arduino and I feel I'm pretty much a beginner, I've never used a voltage regulator before. I want to create this circuit, but I want to hide it in my printer so I want it to work without a battery.

http://hacknmod.com/hack/beginner-spy-tutorial-your-first-diy-mini-fm-bug-transmitter/

I am planning to put a 3 V voltage regulator on it, but I wonder how hot a voltage regulator can get if the maximum voltage is used. And should I be worried about the heat, as in should a try to cool it?


texts: What will happen when the supply and ground are connected for a CPU fan with PWM but the PWM wire is not connected? Will the fan run at its full speed?


texts: Under-voltage lockout programming on Delta D12F200 DC/DC converter

texts:
I recently decided on the Delta D12F200 DC/DC converter for my current project (datasheet: https://www.mouser.com/datasheet/2/632/DS_D12F200-1141659.pdf). My project will be powered by lithium ion batteries, so having a built-in programmable under-voltage lockout will be a big benefit. However, I am having a bit of trouble understanding the formula for programming the under-voltage lockout. The datasheet describes it with the following formula:

What I am failing to understand is where I get "Ven", as this is not described anywhere else in the data sheet. My best guess is that I should read that part of the formula as 14 * "minimum allowable voltage" + 3.8. I am hoping someone with experience on the D12F200 or similar DC/DC converters can help me out here.

I am also a bit confused on how pulling the enable pin low with a certain resistor value changes the lockout. The enable pin will be driven above 1.6 volts to turn the converter on and according to the data sheet, turns off when pulled below 600mv. I also thought of using a zener diode (and possibly a voltage divider as necessary) to control the enable pin state, but I don't want to mess up the programmable lockout due to lack of understanding. I am pretty space limited for this circuit, so I can't use anything more than a handful of components to prevent the battery voltage from dropping below ~8.5-9v under load (3s battery lithium ion pack).


texts:
I have two signal lines, both will be running at the same time on a PCB. RGB lines running at 75 ohms impedance -0.3-+0.7v (1v). (Standard video lines). Currently both lines are active/running/receiving a signal at the same time. Lets just use two lines Red and Green for simplicity. I'm looking for a switch/or method where when Red is active, Green is disconnected. I know this is a very simple question, but I was thinking of using logic gates, but 0.7v is considered low so that wouldn't work. And from my limited knowledge I know that basic transistors only turn on at 0.6v so that wouldn't work either.

If Red is active, Green needs to be disabled. I am not using a cable. It's a PCB design. Switching needs to be done on the PCB circuit


texts:
I encountered this problem in one of my books where the problem asked to find the power loss in the core of an induction motor. I worked through the problem and I found the current as in the picture, but it came to my notice that if I find the power across this load and then find the current that passes through the resistor of interest and finally multiply current by voltage the resulted power would be a complex number. But my intuition tells me that this is a big NO. As it is known that resistors cannot store energy, therefore, a complex power doesn't make much sense.

Now, I found in similar problems that people multiply the magnitude of the phasor of each component to find power across the resistor and they simply ignore the phase angle as if it has zero phase degree. But, I am unable to understand why they just assume that a phase does not exist.

Can someone explain it to me in depth?


texts:
I need to generate a square wave / clock with configurable frequency between say 60 to 500Hz.
There are not stringent requirements on the frequency stability.
I need to be able to modulate this frequency at run time periodically (say once every few seconds) using an external uC using either GPIO or I2C.
I have looked at programmable oscillators and programmable alarm ICs and have yet to find any that can do what I want. I am OK with having a roll your own type of circuit for this as long as it's not super complicated.
The purpose of this is to provide timing control to some external power FETs which will switch a regulated DC voltage on and off. I don't want this switching to be halted if the software running on the uC dies for some reason. So I want an external IC to control the switching.
Can you recommend a circuit that can meet my needs?


texts:
If a device has two ground pins. Using the normal open and short test will not tell if one ground pin is open and the other is good. How to detect this kind of situation?

Thanks.


texts: how to understand unparalleled transmission line?

texts:
in a normal transmission line example, shown as case-1 in below picture, the signal path and return path are parallel to each other, let's say it takes 1ns for the signal propagate from left side to right side.
however, for case-2, the two paths are not in parallel to each other, then how long does it take for the signal to propagate from one end to another? Is it still 1ns? does the current in signal and return path reaches to the end at the same time?
Thanks for your answer.


texts:
I've two step motors with 12V-0.4A each, A4988 as stepper motor driver and CNC shield on Arduino. As I know I should use at least 2x voltage for stepper motors and I would like to know, if I use 24V-4.5A power supply, can it lead to any problem with these devices?

Or should I use something equal to needed current? (2*0.4A + cnc shield etc. let's say 1A for example...)


texts: Are there any benefits to amplify the signal for this case?

texts:
A force transducer together with its amplifier designed for a full scale load such that it has -5V to +5V range as output. But it is only used with loads outputting -200mV to +200mV. A data acquisition ADC is sampling the output voltages.

The ADC input range is -10 to +10V and its resolution is 16 bit.

Are there any benefits to amplify the transducer output in this case? Could you give me a practical example.

(I guess SNR will not improve because noise will be amplified as well)


texts:
While solving these problems I'm confused about sign conventions of output voltages of IDEAL Diodes. Actually I can't get between which nodes the V is to be taken? Is it between +5 and -V? I solve them like this

a) V = +5 (Between +5 and 0) since diode is conducting.

but answer is -5V?  Can any one explain a bit?


texts: What is the main reason why solar inverters fail?

texts: As I understand electrolytic capacitors fail eventually after some years of use. Is there something else that breaks down too? Because changing inverter just because its capacitors are gone is really stupid and expensive.


texts:
I have come across this article:
https://www.powerelectronics.com/power-management/step-down-dc-dc-converter-eliminates-ferrite-cores-50khz-enabling-power-supply-chip

That describes the Cuk DC/DC converter using new GaN FETs as the best in class efficiency with tiny inductors.

Has anyone done this in simulation?
What controller can be used for regulating this topology?


texts: why there are two capacitors in half H-bridge motor driver circuit?

texts:
I am confused with this and the image shown below given about half H-bridge circuits!

Why are there are two capacitors connected if DC gets blocked?(roughly, I am assuming that, to prevent short from Vcc to ground.) Please Help me to understand this!

EDIT: Consider a dc motor instead of L1


texts: Finding the negative feedback loop in the amplifier circuit

texts:
Today I was learning about the negative feedback in the amplifier circuits and some quick ways of discovering whether a negative or a positive feedback exist in the circuit by finding a feedback loop and counting the number of pi-s (phase changes) that exist in that loop.

If we look at the general scheme of feedback in a system we can see that the loop of feedback goes from Output->B->+->A->Output and the total phase change is 0 meaning it's a positive feedback.

Going to the actual circuit in question here is an example from class

simulate this circuit – Schematic created using CircuitLab

Clearly, there is feedback in the circuit. I know in advance that phase shift of a bjt transistor are: BE=0, BC=pi, EC=0.

Now i need to determine the loop and count the number of pi-s that exist inside the loop to determine which feedback it is. To me a logical way of determining this was going from Vout to the input and back and i did it like this:

LOOP: Vout -> BJT 2 CE (0) -> R5 (0) -> BJT 1 BC (pi) -> BJT 2 BC (pi) -> Vout which makes the total equal 2pi which would make it a positive feedback.

This is however not the way they showed the loop in class as the went like this:

LOOP: BJT 2 C -> R5 (0) -> BJT 1 BC (pi) -> BJT 2 BE (0) -> BJT 2 C and the result is pi which makes it a positive feedback.

  Why is my way of finding a loop wrong and theirs right? Isn't the loop always from Vout to Vin or is there something I'm not understanding here?

I'm primarily in understanding this method rather than calculating and figuring out the sign.


texts: Replace potentiometer for Kemo M012 Power Control

texts:
The potentiometer of my (Kemo M012 Power Control) is mechanically broken and I would like to replace it.

However, I am unsure whether the replacement needs to meet any specific characteristics or if any off-the-shelf potentiometer (with the same maximum resistance) should suffice.

Is there actually any load going through the potentiometer ?


texts: Capacitor problem using an NMOS inverter with depletion load

texts:
When Vin is low the enhancement type NMOS is off. That means the drain current of both transistor is zero, isn't it?

If it is, then how will the parasitic capacitor charge? I'm not understanding! And if it charges, how much will the maximum capacitor voltage be?


texts: Linear regulator with remote load sensing and voltage tracking

texts:
I am trying to design a linear regulator with following requirements:

(R1) Output current range: 0 to 1 A.
(R2) Output voltage range: 0.9 to 1.5 V.
(R3) Output voltage range is to be swept in 10-20 mV steps. I think it would be easier if the output voltage is set by an externally applied voltage reference. I do not see how to achieve this using regulators with an internal fixed reference with output voltage typically set by a resistor divider. It should be possible using a digital potentiometer IC. However I would prefer to keep it simple and avoid using a microcontroller to program the digital potentiometer.
(R4) True remote load sensing (Kelvin sensing). Kelvin sensing is needed because there is a current sense resistor of 50 or 100 mohm in series with the regulator output. Connecting traces and wires are expected to contribute 10 to 20 mohm.
(R5) The required accuracy/precision of the output voltage at the load is < 15 mV (or 1%).

The regulator is part of a custom/dedicated test bench.
The regulator and the load (device under test) are on separate boards. The distance from regulator to load is approximately 30 cm.
The source voltage for the regulator circuit is provided by bench power supplies. They deliver 0-8 V and 0-5 A. It is not an issue to use 2 or 3 of them if needed. However using bench power supplies to power the DUT would need too many PSUs and is not an option.
The load (DUT) draws a quasi constant current. I am not expecting large load transients. I plan to put large decoupling capacitors on the DUT board nevertheless to avoid stability issues.
The device under test is an IC with over 20 similar power rails. All the DUT supply rails are to be powered at the same voltage. Current must be measured separately for each supply rail. Thus I plan to duplicate the regulator circuit multiple times on the same board. I would like the design to be as simple and compact as possible and therefore I would prefer a solution based on an integrated circuit. However I would consider other options such as implementing a linear regulator from an op amp and a discrete pass element if no regulator IC fits my requirements.
How can I design a circuit that would provide both remote load sensing and voltage tracking?


texts:
I'd like to experiment programming the mbed's LPC1768 dev board (https://os.mbed.com/platforms/mbed-LPC1768/) using ISP with FlashMagic.

Is this possible without requiring physical modification of the board?


texts: DC-DC Boost Converter \w Inrush Current Protection - Voltage

texts:
I wanted to dive in Power Electronics and create a 24V DC-DC Boost Converter that would run from 2.5 to 5 V power supply. 80% efficiency was assumed, and 30 kHz frequency chosen for the PWM.
Initial Parameters

Duty Cycle
Assuming the forward voltage drop of a diode was 0.5, duty cycle was calculated in the following manner.

Inductor & Capacitor
I only had 220μH inductor & 100μF capacitor around, so those two have been chosen for the circuit.

Circuit
Here is the DC-DC Boost Converter circuit with the inrush current protection.

PWM signal is generated by PIC10F200, and PWR is 2.5 - 5 volts.
Problem
I have made the circuit on a perfboard, and it is working perfectly. However, the output voltage is much higher than expected, around 75 volts, and has fried my regulator as I have omitted the Zener regulation.
Were my calculations wrong, should the PWM be tweaked?


texts:
I have a capacitor for which I would like to get the output impedance as a function of the frequency. I would like to get something like this:

For this I have a spectrum analyzer with an output which allows me to set an input voltage on the capacitor at different frequencies:
Here is the equivalent schematic:

simulate this circuit – Schematic created using CircuitLab
Well there is something that I do not understand to obtain Zc:
Suppose I did not connect the capacitor, there is just a voltage divider. So I shoud see Vout = Vin/2, ie -3dB. I have actually 0 dB, so it seems to measure the output volage after the 50R resistor. Nevertheless if that is the case, Vin is always equal to Vout. How does that works? Then I could deduce the transfer function Vin/Vout, get the gain and obtain at least the magnitude of Zc as I would have no information about the phase.


texts:
I have the following problem:

Consider the ciruit and problems below.

The head of the voltage arrow denotes the \$-\$-pole of the voltage drop.

Okay, for the first problem I just used the simple formula for DC-gain for an op-amp modelled like this. I arrived at:
\$A_v = \frac{R_2}{R_1}=\frac{220 \text{k} \Omega}{51 \text{k} \Omega}=-4.31 \frac{V}{V}\$
But for problem 4.2, I'm not sure what I'm supposed to do. If it asked for the time constant for the capacitor in the circuit I might be able to figure out an answer. But they are asking for the time constant for the pole/zero for the filter.
Does a pole/zero have a pole? And if so, how do you the time constant.
I hope someone can help me with this.


texts:
What exactly is offset of the amplifier? How do I measure it?

In my measure lecture, lecturer told me to measure the same voltage in right polarity and opposite polarity. It should be enough to compute offset, but I can't find how to do that.

I know the amplifier has gain \$100\$. And it's noninverting. Values were \$138\ mV\$ with right polarity and \$-152\ mV\$ in the opposite.

I've read, that ideal amplifier has zero Offset when input voltages are equal. So is it possible to say, that offset is the value of the amplifier, when inputs are equal? Than the offset in my case could be \$\frac{|138-152|}{2}\$?

If the scheme is somehow important:


texts: Dividing the rotor circuit by slip in induction motor

texts: In this article equation (3), just after figure 5, they divided everything in the equation for current by slip. I understand that current remains the same when doing this, but voltage and power would change by dividing everything by slip. Why do they do this and how is it equivalent when analyzing a circuit?


texts: Switching Power Supply Chirping, How to Fix?

texts: I have a Dedicated Micros UP07223010 power supply that gives out a chirping noise. A voltmeter attached to the terminals shows a swing for each chirp. A few days ago, my HP laptop power supply developed the same chirping problem and had to be replaced. So I assume it is quite common. Here is a picture of the interior. The three bigger capacitors near the center with gold marking (3300 uF, 16V) look to be a bit bloated. Could they be the problem?


texts:
I have the following setup:

Very small PCB - 25mm in diameter that hosts chip antenna;
I feed directly into antenna matching network with about 7.5cm coax via ufl connector;
There are no other components on the board as I'm testing antenna only.

I use miniVNA Tiny to get some meaningful vision into the quality of RF that was proposed by the vendor. I calibrated it at the end of coax, so that I basically measure the antenna only.
Scanning the entire supported range from 1MHz through 3GHz produces the following results:

Which looks too good to be true. The frequencies I'm interested in are around 900MHz, 1.5GHz, 2.5Ghz, ie LoRaWAN, GPS and WiFi, and it looks like all good.
I really would like to play the devil's advocate to make ensure this is nothing wrong with my setup and I'm reading the right values.
What concerns me is that no matter how I try to confuse the antenna either with a metal object nearby or anything similar, fundamentally the outcome is similar in terms of values/diagram.
Update
A nice link that has lots of goodies at the bottom https://www.nonstopsystems.com/radio/frank_radio_coax-sw.htm


texts: How to use a sprinkler valve in multiple zones?

texts:
I am currently setting up an outside irrigation system.  When I built the system, I thought the irrigation controller would allow me to power multiple zones at the same time, and that each valve -  could be plugged in and used as a zone.  Unfortunately, that’s not how it works — only one zone is powered at a time, and multiple valves can be wired to a single zone.

My problem is: when you wire a valve to be in two zones, the current back feeds and turns on incorrect valves in another zone.

I did some research (How to keep voltage when using two diodes to run two irrigation stations?) and found that if I use a full rectifier and diode on the hot wire to each valve, I can accomplish what I want.  I diagrammed out the idea that I think will work, but I’m concerned about how the circuit will work when going through the rectifier from the common line — it looks like it will still power valves that I don’t want to power.

My question is: how can I prevent the common wire from sending current to the undesired valves from the rectifier?  (Not pictured in diagram)

Other notes: The controller uses a common wire (shared to all valves), and a hot wire (24VAC@1a) individually to each zone.


texts: Identification of line code from amplitude, phase and PSD plots

texts:
I recorded some transmitted data using the Noo-Elec RTL2832 software-defined radio. The data is transmitted at a carrier frequency of 1.3GHz and sampled at 2.4MHz. The transmitted data is a set of line codes, each linecode starts with an ASCII space and is followed by 21 ASCII characters with short spaces between linecodes. I imported the raw 8 bit IQ data into python and split up each burst of data into seperate arrays to begin classifying each linecode individually. The IQ samples are converted to complex samples \$I +jQ\$ for ease of use. These complex samples are stored in a single column python list data type. The first plot shows the real component of the line code plotted against time, the second shows the phase plotted against time (I have applied an unwrapping algorithm to it) and the last is the power spectral density against frequency. I'm having trouble identifying the following two line codes:

How can I use this data to make an informed decision about what these line codes are?


texts: Force the state of floating digital input to particular level

texts:
Given: a microcontroller in QFP package. A pin is configured as digital input, no pullups/pulldowns. The physical pin is not connected to anything else, besides the pad on PCB.

Is there a way to force the state of the digital input (high/low) without physically touching the pin? Electrostatic field? Heating the IC to increase leakage current in clamping diodes?

To those wondering why: suppose you are working on a complex system. In the previous HW revision, there was a button + pullup/pulldown resistor. The button and resistor was removed in the next hardware revision. The firmware team did not remove the code which was processing the input, just initialized the system to desired state. Since the software still reacted on long button press (not just rising/falling edge) and did not have sufficient logging, this led to very hard to debug issues down the road (requiring multiple man-weeks of debugging to find the root cause).

What I'm looking for is a relatively quick test to see if there is no software reaction to "supposedly unused" input pins changing state. Auditing the full software running on the MCU is non-trivial task (>1M LOC).


texts: Severe ringing when high side MOSFET in half bridge circuit switches on

texts:
I have designed a PCB (intended as a prototyping building block) that has a IR2113 high and low side gate driver driving two IRF3205 (55V, 8mΩ, 110A) power MOSFETs in half-bridge configuration:

Picture of the physical setup

Upon testing the circuit with a load I found out that while the low side switches quite cleanly there is a lot of ringing at the output of the half-bridge (X1-2) every time the high side switches on. Playing around with the input waveform dead time setting and even removing the load (an inductor with a power resistor in series simulating a synchronous buck converter connected from X1-2 to X1-3) did not reduce this ringing. The measurements below were taken with no load connected (nothing at X1-2 except for the oscilloscope probe).

Apparently the parasitic inductances and capacitances are enough to cause that, but I cannot figure out why the low side works as well as it does. To me both gate drive waveforms look clean enough, with the voltages transitioning the treshold voltage of the MOSFETs reasonably fast. No shoot trough is present when switching. What are the possible causes of the problem, and what measures can I take to reduce the symptoms?

I am aware that there are many very similar questions here and on other sites, but I found the posted answers unhelpful for my particular problem.

Edit

While there was a 2200uF electrolytic capacitor at the input (X1-1 to X1-3) to supress transients and noise, it clearly failed to supress any high frequencies. Adding a 100nF capacitor (as suggested in the answer by Andy aka) in parallel with the electrolytic one reduced the ringing at the output (X1-2 to ground) by half and ringing at the supply (X1-1 to ground) by a factor of 10.


texts: Does anyone know how the low tone control of the Boss Metalzone works?

texts:
https://electricdruid.net/boss-mt-2-metal-zone-pedal-analysis/

https://sound-au.com/articles/gyrator-filters.htm#s9

I have been using these websites to try and work out how the eq works, but I've had a bit of a problem when it comes to the gyrator used for the low tone control. I can't quite seem to work out the relationship between the frequency response and the components.


texts: Connecting a ring terminal to a smaller stud

texts:
This 12V DC breaker panel is meant to carry up to 100A, but provides a fairly small stud for terminal connection.  The product documentation doesn't appear to indicate the stud size; it was measured with a caliper at 3/16" (#10).  The product manual itself recommends use of 2 AWG wire, for which ring terminals/lugs smaller than 1/4" do not appear to be manufactured.

Is it generally safe to use a 1/4" ring terminal on a 3/16" stud?  Are there any special considerations?  If I were to add a flat washer to stabilize the connection, how would I know what material it should be made from?


texts: Electricity not conducted by copper wire

texts:
Im am quite stunned as to what might be wrong.
electronics beginner

I bought today some copper wire, 20SWG /0.9MM from maplin (UK), for a project I am working on.

There is no power going through the wire. I got positive and negative of 9V battery going to breadboard, then two pieces of copper wire one in + one in -. No voltage on the multimeter. Exact same setup with jumper wires work.. Copper wires are inserted fully into the breadboard... What am I missing ?

p.s Label says: 250g EN COPPER 20 SWG 0.9MM


texts:
I bought a RGB LED strip (analog) and it has one 12 volt and three ground pins that is pwm controlled (I assume) to dim them.
I also want to add a 12 volt white strip that turns off when the RBG turns off.
Sadly turning the controller off does not switch off the 12 volt but disables the ground pins.
So what can I do to make the white toggle with the RGB without dimming with the colored grounds?

I want the white to turn on when any of the RGB is on, and the white to turn off when all the RGB is off.

My thought is to have some kind of logic OR that essentially detects if any of the three wires have ground then also give ground to the white strip.
But I'm not good enough with logic gates, never actually used them only seen them in school about 25 years ago...
I can get both 12 volt and ground before the controller/driver.


texts: 12Vdc 5A Power supply electricity consumption

texts: i am using a 12Vdc 5Amp regulated power supply to power some Led lights.The total consumption is 2Amp. I need to understand if the power supply consumes less electricity(230Vac) if i do not use all 5Amps available or is the 230Vac usage the same? Thank you.


texts: Calculate number of states in edge triggered flip flops

texts:
Consider the sequential circuit shown in the figure, where both flip-flops used are positive edge-triggered D flip-flops.

simulate this circuit – Schematic created using CircuitLab

The number of states in the state transition diagram of this circuit that have a transition back to the same state on some value of “in” is _.

My question is how can we calculate a number of states in above diagram. Is there any formulae for that or any logic to calculate?


texts:
I'm an Electrical Engineering student still new to power systems. I'm working on a project that uses a 24V and 200Ah battery bank made up of 4 AGM lead acid batteries. The batteries are supplying four brushed DC motors, the motor drivers, various sensors, and two Arduino Megas. Maximum continuous current draw from the system will be about 80A total. I need a safe way to create a battery disconnect for the system that is controlled by a large push button that is remote from the battery bank.

I've been looking at contacts and relays as well as a key actuator disconnect switch like one on McMaster-Carr (item # 7110K42). It is rated for 100A at 12VDC. I should mention that the product is on a tight budget which is why this is an option as opposed to a contactor.

I am wondering if it is possible to use two of the key actuator switches, since the battery bank is composed of four 100Ah 12V batteries, and an actuator switch could be placed somewhere in the battery bank that could disconnect power to the whole system safely.

I am worried about the specific placement and also potential arcing during switching. I'm getting buried in research and am just hoping for a little input or guidance on which direction to continue research and tips on how to proceed.

Much thanks.


texts: Simple delay functions for TI Launchpad?

texts:
In Atmel Microcontrollers, there are simple delay functions such as __delay_ms() and __delay_us() found in utils\delay.h.

I am using a Tiva™ C Series TM4C1294 development board, with a TM4C1294NCPDT microcontroller. However, I can't find any libraries to do similar delay functions.

Will I have to write my own delay function? I know it's not that hard, but I'd rather use an existing library if there is is one.


texts: A 810nm led has a 350mW/sr rating. How do you convert to mW/cm2?

texts:
This led:
https://www.digikey.com/en/products/detail/vishay-semiconductor-opto-division/VSMY98145DS/7041914
Has a 350mW/sr rating.

How do I convert this to irradiance in mW/cm2?
Can you achieve a lower irradiance by lessening the input amperage or voltage?


texts: How to calculate gate charge time for a mosfet?

texts:
I am designing the circuit shown above using mosfet NDS355AN. MCU is 5 V.
However, I have become stuck as I am unsure of how to calculate the gate charge time of the mosfet. Hence what is the formula to calculate the charge time for the gate of the mosfet?

Is it just essentially tau = RC = 1500 * Ciss?

Note LED contains resistor inside (is a very large all in one)


texts:
I have a circuit with resistors, capacitors and inductances. I need to plot the output impedance of this circuit for different values of two components in this network. Do you know a program (either freeware or matlab) which I can use to do this?

Thanks in advance.


texts: AC Analysis of emitter circuit, why can I ignore resistance R1 but not Rc?

texts:
I am trying to calculate the small signal voltage gain of this circuit but I am having a problem comprehending the last step.

I rewrote the circuit like this

But the solution says this:

Which would equal to Ua/Ue = -(ßiBRc)/(rBE+RE(1+ß)) which is nearly -Rc/RE

Why can I ignore the R1||R2 resistance but not the Rc resistance ?


texts: Microcontrollers, FPGAs, ASIC (Application-specific integrated circuit) all are used for similar type of applications (at different levels). I know about microcontrollers and FPGAs. But what is an ASIC really? I have a hard time understanding why we have all off these very similar technologies.


texts:
I'm looking at existing circuits and trying to understand them so I can design my own. Also to improve my electronics knowledge, for some reason MOSFETs have never quite sunk in for me.
I came across the circuit for this board (the files from here (Rev D)) which the company are gracious enough to share.
Please educate me if I am wrong but is this MOSFET upside down? I know it is a PMOS as the arrow from the gate is facing outwards, and that the arrow/diode connects to the source so the source is at the bottom and the drain is connected to VBAT.
My thinking of their intention is for the 100k R to be a pull-down and that when VBUS is not present, the gate is pulled low, switching on the MOSFET and connecting the VBAT to the LDO.
When the VBUS voltage is present, the gate would be pulled high, turning off the MOSFET, disconnecting VBAT from the circuit so it can be charged.
However for that to be true I believe the PMOS source should be connected to VBAT and the drain should be connected to the load - the LDO? This would also result in the body diode facing upwards, conducting towards Vdd as it usually does.
As a bonus question, when VBUS is connected wouldn't it be wasteful constantly dropping a voltage across the 100k resistor (the left one)?


texts: Is this the proper way I'm calculating RMS?

texts: I'm trying to calculate RMS value of the given graph. Am I doing this right?


texts:
What are pros and cons using Wiznet W5100 or Microchip EncX24J600?

It's a bit complicated to explain.

My question is about the performance of Microchip TCP stack vs Wiznet TCP/IP core on the chip. Also about the costs ($$).

For example:
With Wiznet, the microcontroller will have less processing, thereby freeing the microcontroller to do other tasks. But I think that this will depend of which layer you are working.

With Microchip TCP stack maybe I have limitations on the peripherals that I can control. Maybe I'll have to use a second microcontroller.

So, I hope I've explained better now for you to help me in the best choice.


texts: How to estimate active-power transmission capacity based on voltage levels and line lengths

texts:
I know voltage levels and line lengths of high-voltage transmission lines and I am looking for a rough estimation of the maximum active-power transmission capacity during normal operation. By normal operation I mean power levels that can be sustained over long durations. I understand that many factors are impacting this and that a 1-to-1 map from voltage to active power level is hard to give. But I am looking for rough estimations only, and I am happy with any upper-bound, lower-bound, or range estimations.

An example would be: out of my window, I can see a transmission line and all I know about it is that it's a single-circuit 220 kV line. In which range will the active power capacity of this line be?


texts: How can 24 V (two 12 V batteries) x 100 A power a 5 kVA (or 4000 W) inverter?

texts: I am a beginner at this. I know that energy cannot be created nor destroyed. I know you can't use 3 kVA inverter to run a 5 kVA dynamo (assuming I want it that way). Why then is 2400 W (12 V x 2 x 100 A) able to power some 5 kVA (4000 W with 0.8 power factor) inverters? Is there anything I don't understand?


texts: Pressure/force map (0-5kg) via sensor grid

texts:
I have a surface 40x36 cm. I would like to recognize the shape and weight of specific objects on that surface. Here is the "big picture".

The first idea was to use touchscreen overlay (infrared or something like that) + single weight sensor but I need to recognize shapes (and not single points) so that's not going to work.
Second idea was to use something like MTmini but I don't have that much space below my surface - eventually I have 5 cm at max.
Third idea (current one) is to use pressure map with 20x20 (or something similar, not aware of sensitivity of the sensors and possibility to extract shape from it) sensor grid. Something like foot mapping sensor in this question.

So the idea is that I have blank surface and if I put rectangular object which weights 1kg I can recognize where it is exactly on the surface, what is it's shape and weight.

Blue overlays are common sizes of objects that will be on that surface.
Weight of single object will range from 0 kg to about 5 kg - I need at least 20-50 g precision 0 kg to max. 3 kg (usually around 500 g) - I need at least 50 g precision. Anything larger than 250g will sit on multiple sensors so I think that 0-1kg range per sensor is max (precision 50g - 5%) or better yet 0-500g per sensor with 50g precision is 10%.

My question is, what type of sensors to use (I though about piezoelectric ones?), how/where can I check their "sensitivity"/accuracy and where can I get them (cost)?
Also if you have some experience, how dense should be my grid? 10x10? 20x20? 40x40? Probably all multiplexed.

Probably I would connect it all to RaspberryPi (or Arduino?) for calculations and analysis.


texts: Most efficient way to convert 6 V to 5.5 V

texts:
My goal is to design a USB charger for my phone/tablet when I don't have access to the power grid.  I've used a LM317 with a 12 V, 5 A·h SLA battery but it does not provide enough capacity due to the power dissipation of LM317:

$$(12~\mathrm{V} - 5.5~\mathrm{V}) \times 700~\mathrm{mA} = 4.55~\mathrm{W} \approx 5~\mathrm{W}$$

The LM317 burns about 5 W as heat.

I need to convert 6 V from my battery to around 5.5–5.6 V (AC USB charger voltage at 500 mA load) to charge more efficiently and decrease battery weight (half the cells, half the weight).

I've tried designing a op-amp regulator with a MOSFET but the VGS threshold is just too high for the op-amp to turn it on—it takes a VCC of about 8 V which starts to increase my heat losses to unacceptable levels.


texts: Home project about detecting harmful gases

texts:
I am designing a PCB for detecting harmful gases (below is the schematic in Eagle). I have used MQ7 and MQ135 sensors, and the ESP32 WROOM32D MCU.

For the power supply, I have used HLK-PM03 since I'll be using 240 VAC and the HLK-PM03 will convert 240 V to 3.3 V.

My questions are:

I need to convert 3.3 V to 5 V since the sensors need 5 V. So for that, can I use MCP1640 boost converter? Since my design is AC to AC and this booster is DC to DC, is it good to use? If not, what is any recommendation for the booster? (I need to make my PCB small, so I am looking for an IC.)
The MQ135 can detect multiple gases, so how will I know which gases this sensor has detected?
For the MCU part of the design, if any modifications are required or something is wrong, please let me know about it.


texts: What is the simplest way to interact with an I2C peripheral?

texts: I have an I2C peripheral that I need to interact with using a Windows 7 PC. The interaction could be through a terminal emulator, or any program that can produce a real-time log that I can process using a scripting language. Based on your experience, what is the least painful way to achieve this?


texts: what are these two fm antenna connectors? How can I join them?

texts:
One of these connectors is the type that plugs into my receiver's FM antenna input, and the other is an aftermarket FM antenna output connector.  I think the one with threads is called "type F" but my searches are coming up with a lot of garbage, hence I'm not sure.  The other one I'm not getting even a poor answer.

Is this ANT-108?  I have my doubts.  The back of the receiver is, of course, the mating connector, and that's what I really need to join up with, not this thing.  But I can't easily
get a picture of the back of the receiver, sorry.

I believe this is "type F".
I want to join the bottom (type F) connector to the mate of the top connector.  Should I consider getting the mates to these two connectors and hacking up my own bit of wire between the two cables?  Or can you tell that this aftermarket antenna just isn't supposed to be connected to this kind of receiver?


texts: Why isn't Voltage considered in mAh ratings?

texts: The capacity of a battery is measured in mAh, for example a 1000mAh battery can provide 1A for 1 hour. Why is voltage not considered in this equation? 1A at 5V draws twice as much power (P = V*I) as 1A at 2.5V, which would surely drain the battery twice as quickly? The only reason I could think is the mAh is calculated on the output voltage of the battery in which case how can we compare batteries using mAh ratings?


texts: In Common Emitter Amplifier Circuit ,Emitter Capacitor effect

texts: I was wondering about the Effect of Emitter Capacitor in Common Emitter Amplifier? It is Suggested that Putting the Bypass Capacitor the output voltage gain is increased but how? As we want more output voltage? I feel The Effect of Capacitor is to reduce the Resistance. Decreasing the resistance ,does it increase the voltage?


texts: ADC readings problem: built in vs external ADC unit

texts:
Why am I getting these (mostly) good readings with the built in ADC of the Arduino Uno (10 bits resolution):

and these scattered values (same analog sensor used) with the external LTC1418 ADC (14 bits resolution of which the last 2 bits were dropped) ?

For what is worth, the sensor is an G-NSDOG1-006
Also I once had this anomalous outcome from the built in ADC:

I am using the external ADC as shown in "Figure 24. Internal Conversion Clock Selected. Data Transferred After Conversion Using an External SCLK." at page 25 of the spreadsheet above. All of the readings were taken at every 0.5 seconds.

The electrical schematic is what they recommend in the same document:

The LTC1418 chip is soldered to a SSOP-to-DIP adapter PCB which is inserted into a solderless  breadboard.

My final goal is to stabilize the external ADC unit (the LTC1418 chip)'s output.

Thanks!

edit1

In response to @Brian Drummond

Good thinking!

For the supposedly stable 3v3 output from the arduino and USB power
the jitter stays within 11 units.
For the supposedly stable 3v3 output from the arduino and battery
power the jitter stays within 6 units.
For the GND and USB power the jitter stays within 5 units.
For the GND and battery power the jitter stays within 5 units.


texts: Should I add Capacitance on Switched High Side

texts:
Following from this question, which remains open... if I've got a microcontroller switching the high-side power to a sub-system, using a circuit like this:

... should I add bulk and/or decoupling capacitance on the SENSOR_5V net? I do have bulk and decoupling capacitance on the +5V net. In the broader context of this circuit, SENSOR_5V basically just goes to a connector pin, which supplies power to a separate board through a short cable.

So, now I'm wondering (in light of the referenced prior question) whether it would be a help or a hindrance to add say a 10uF ceramic and a 100nF ceramic to the SENSOR_5V net? Or maybe even a 100uF tantalum perhaps? What do you think?


texts: Voltage controlling a SMPS via a potentiometer by Arduino

texts: I have started a new project. The idea is that in a SMPS we will have the potentiometer at the back so that when we vary the pot the output voltage will change. We are currently doing it manually, but my idea is to have the pot controlled with an Arduino. How can it be made? Please help me I am running out of time.


texts:
Recently, i see such a circuit in a board schematic, but can't figure out how it works, why the first Op Amp has positive feedback ????

Thanks.

Question, again, now i complete the circuit with part number and values, just as below.

By simulation with  PSpice, i know the "AC coupled" negative input of the comparator is to synchronize the oscillation frequency of the generator. But it seems there is one 'working window', if the pulse rate is two high, the output wave form will be oscillation on the amplitude.

I want to know if this a 'classic' or a widely used technique. And i want to know if there are some accurate mathematical method to predicated the behavior, particularly the synchronizable frequency range.

Thanks.


texts:
This is one of those beginner questions, so sorry about that.

I'm trying to add wireless chip to my current PCB, but there are no more available UARTs on STM32F103. There is one UART (RX,TX) pins "reserved" for on-chip debugger/programmer.

So my question is: Can I share this UART between the Wifi controller and programmer?

Like disconnect the wifi when I run programmer, and otherwise?

Or can those devices run in the same time?

If so, What it would also take from the software standpoint?

Thank you


texts: What does the power rating of a BLDC motor specify?

texts:
If a BLDC motor has a power rating of say, 500W.
Is this a measure of its power consumption at specifically full speed?


texts: How to plot I vs V for multiple circuits in one graph? (NgSpice)

texts: I have to see the I-V characteristics for five different LED model files. I'm using ngspice and I want to plot all five I-V characteristics in the same graph. What do you think I should do?


texts:
Suppose you have this circuit diagram,
I do not understand my professor's lecture. My professor said that AB equal 10 is restricted as when it is changed to 01, it would cause q to be either 1 or 0 depending on the delay of the circuit elements. Could you clarify how such thing happen. After consulting the textbook, this is what it says:

  "AB = 01 is a hold input combination,  AB = 00 and 10 are reset input combinations, and  AB = 11 is a set input combination.   This is reset dominant latch where S =  A  and R = B'.    P  = Q' + B'.   In each stable state P  = Q' even for the input combination AB = 10 (SR = 11) so P  is usable as  Q'.
  Allowing the input combination  AB = 10 (SR = 11) would result in unreliable operation if both  A  and B could change at the same time, i.e., change to  AB = 01 (SR = 00), because the latch could end up in either state  0  or  1  depending  upon  the  delays  in  the  circuit."


texts: Is there a limit of how many times I can hit a TVS diode with an overvoltage?

texts:
I have a system that is powered by 2 batteries that are OR'd together through 2 diodes. They are powering up a speed controller that drives a motor.

Right now, when my motor brakes, I am getting an overvoltage on the input of the speed controller. Normally, my battery will absorb the overvoltage and everything would be great, however, since I started Oring the batteries the path back to batteries is blocked by the diode and I am seeing an overvoltage of 30V on a 50V system so 80V total.

simulate this circuit – Schematic created using CircuitLab

The only thing I can think of is to get a TVS diode and size it correctly to stop any overvoltage, however, the event can happen multiple times at a fast rate. I have not measured it yet, but I suspect that it can happen up to 20Hz. Will a TVS diode be sufficient here? Is there a recovery period for a TVS diode is I guess what I am asking.

The other issue is my system power supplies that are connected on the same node as the motor controller can not handle more than 60V, and I couldn't find a TVS diode that has a working voltage of 50V but a voltage breakdown of anything lower than 60V.


texts: LEDs only light up when my fingers are near arbitrary parts of the circuit

texts:
I am currently trying to build a 4-bit adder and I've run into an odd problem.
The LEDs only seem to light up if my fingers are near, seemingly arbitrary, parts of the circuit. I have only connected two bits so far. The circuit seems to work as intended, I also tested it on TinkerCad.
0+1 returns 01 a.k.a 1 in decimal
1+0 returns 01 a.k.a 1 in decimal
1+1  returns  10 a.k.a 2 in decimal
I just don't get why the LEDs are behaving oddly.
Look at the TinkerCAD sketch for the circuit, my build irl is basically identical with the only difference being I've rotated the dip-switches 180 degrees so the numbers of the dip-switch are facing upwards. I have also logically so connected the dip switches to low (negative) instead of the high (positive) you see on the TinkerCAD sketch.

Irl mine would be:

I am running it on 5 volt. The resistors are 1kOhm resistors.
XOR gates are of the model 74HC86N
AND gates are of the model 74HC08
OR gates are of the model 74HC32
See video for clarification video.


texts:
I am using a PID Neural Network (PIDNN) algorithm to control a multi-zoned temperature hardware. The aim of the algorithm is to minimize the error with the Backpropagation rule and weights updating.

The device is commanded by B&R X20CP1484 CPU.

Unfortunately, the device has a very large inertia (SetTemperature 60°, ActualTemperature can reach 72°). Stabilizing the system requires a very long time, but always with few degrees above and below. PS: This is the case when controlling only one zone (the model has 4 zones, let alone controlling the 4 zones).

I thought about decoupling, and added all necessary equations. Still, the system has a very large inertia, heating is unstoppable. I am using a PWM too, so when the sensor value is equal to set value, duty is 0. Then temperature keeps rising even when the heater is off.

The question is: Are the PID parameters wrong? Is there a problem with the PWM period?

The same model was controlled before with GPC and had perfect results.

Device is using 4 SSR, the 4 sensors are few CMs close to the thermocouple.

Any suggestions? Thanks in advance.


texts: Aluminum Electrolytic Capacitor Venting Creating Condensation in Enclosure

texts:
Has anyone ever come across significant condensation on electrical components inside an enclosure due to venting of aluminum electrolytic capacitors ? My 560uf 400V Chang capacitors (believed to be aluminum elec.) have vented, and there is significant water condensation in my enclosure. I suspect the venting was caused by water ingress (< IP55) which shorted the capacitors, but I want to make sure that the venting discharge isn't the cause of the water condensation.

As anyone else experienced something similar ?


texts:
I am building a voltage regulator with the LM22678-5.

I used TI WE-Bench designer to get the component values needed for the regulator:

The regulator outputs 5V when there is no load however it drops to around 2-3V when a load is connected. Ceramic Capacitors were used for Cin, Cinx and Cbst. Cout is an electrolytic capacitor (35SVPF120M). Below is the PCB layout I used.

Note: Although the PCB has the enable pin tied to VIn I just don't connect that pin to the IC and leave it floating as per the datasheet.

This is the output on my DSO:

Does anyone know what I am doing wrong?


texts: How does this USART level shifter circuit work?

texts:
I'd like to ask how this circuit works:

I understand how it works in principle, but not technically. It's a USART voltage level shifter. It's supposed to divide 5V to 3.3V by a resistor divider, in the direction from microcontroller (on the left ATMEGA328), to RFmodule which works with 3.3V. But in opposite direction, a transistor has been used which I do not understand. Arrow above R8 resistor indicates 5V.


texts:
In a LED (light emitting diode,) a forward bias allows electrons to fill the vacancies in the p-type region, recombining with holes to emit a certain frequency of light.

After a set amount of recombination occurs, I visualize that all of the recombined electrons are at a lower energy, and other electrons that are getting pushed by the voltage difference flow directly towards the other end of the diode into a wire.

Do these electrons actually push out recombined electrons, and recombine with the created hole again? Isn't a lot of energy lost when achieving the activation energy of an electron (removing it from the valence band,) reducing the length of emitted wavelength?

Thank you for clearing up my confusion about electric current.


texts: What is the purpose of a relay between a switch and motor?

texts:
I was disassembling a belt disc sander today and noticed that there was a rather large relay between the switch and the motor. The relay consists mostly of a large copper coil. The motor doesn't have a capacitor and neither does the switch assembly. There are three wires coming out of the motor: red, white and black. All of the wires are of the same size about 14AWG.

When I tried wiring the motor without the relay, I couldn't get it to start without turning the shaft by hand. This would mean that the relay was acting as a starter. I am perplexed because I was under the impression that the only way to start a motor was either by hand or a start capacitor.

Can a relay be used to start a motor, if so, how?