texts: How to open a LTspice encrypted .mod file in LTspice XVII?

texts:
i want to use a capacitor model in LTspice XVII.
On the TDK webpage are a lot of models of their capacitors.

I chose the DC bias model (LTspice) of the C3216 commercial grade (up to 50V) C3216X5R1V226M160AC capacitor.
After downloading the .rar file i extracted all models in my \LTspice\lib\sum\TDK\C3216 directory.

The .mod file is encrypted for LTspice.
So i will not be able to read all specs of their capacitor, but i can use it as 'black box' model at least.
The problem is that my LTspice is not able to open the .mod file.

I don't know why!
The first line of the .mod file says:

* LTspice Encrypted File
* This encrypted file has been supplied by a 3rd
* party vendor that does not wish to publicize
* the technology used to implement this library.
* Permission is granted to use this file for
* simulations but not to reverse engineer its
* contents.

In the file C3216X5R1V226M160AC.asy i found the line:

SYMATTR ModelFile C3216X5R1V226M160AC_b_LTspice.mod

So it should find the .mod file...

I am using LTspiceXVII on win10 x64.


texts: Extremely high current in super simple SMPS Flyback

texts:
I'm building an SMPS in flyback topology. In order to do it, I use UC3845CB IC. In first step, I wanted to see if it even works at all with pulse transformer that I bought, made especially for flyback pulse power supply.
Below is the schematic for circuit that I've built. It is supplied from bench power supply with two outputs (+10V from output A and +20V from output B) connected via ground.

I connected all pins responsible for current and voltage control to ground in order to get simplest possible configuration.

When I turn only the +10V output, there is quite little current flow (0.01A).

But as soon as I turn on +20V, current on output A (not B!) rises dramatically (up to 3A), while current on output B is much lower (something like 0.3A). Strange thing is that IC does not heat up at all! And it is not burned either - when I turn off B output, I get 0.01A again on output A, and waveform on MOSFET gate is correct (50% PWM with 17kHz).

When I measure voltage on C2, it shows around 300V.

Also, when I turn ON only output B, there is no current flowing in the circuit.

Ratio of winding on the transformer is 56:14.

I'm totally confused, but again, I'm a total newbie regarding pulse power supplies. Anyone got a slightest idea what is going on?!

Edit:
I changed the picture to better illustrate what is going on


texts:
https://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-004-computation-structures-spring-2017/c12/c12s3/procedures_answers.pdf
I don't understand how the linkage pointer can be the same value for multiple iterations in problem 2. Shouldn't the BR(f,LP) instruction change the LP value?
Here is the doc for the ISA: https://computationstructures.org/notes/pdfs/beta.pdf


texts: How does pulse width modulation use ground

texts:
I have a big missunderstanding about how pwm (ground) works. Does input and output of a PWM (including step-down dc2dc) share the same ground ? If so how can i have an input in 12V 50% duty cycle (6V output) that use like 1Amp . Then 6V * 1A = 6W but the 12V input will use 0.5 Amp to have same power .

How can there be common ground if on output i have 1A and input 0.5 Amp. I tried to search google to better understand ground in PWM but everywhere i look it talks about duty cycle and stuff like that.

Can someone make me understand GROUND use in PWM ? (+including step-down regulators that use PWM i think).

Thank you very much.


texts: Practices for using a scope, scope probe and termination resistor for a proper measurement setup

texts:
In a setup, assuming a function generator has 50 Ohm output impedance and a coaxial cable has 50 Ohm characteristic impedance. Therefore to prevent reflection of a signal a 50 Ohm termination is used. But for many people I know they dont use 50 Ohm termination for basic use(non RF)
 and they also use 1X probe with scope's 1X setting.

And if we use a 50 Ohm termination then our signal's amplitude halves. How is this problem compensated? By setting the scope to 2X? How about the probe? 1X or 10X?

What is the proper probe/scope and termination resistor setup depending on the signal frequency? Can we roughly make a category? I want to learn the proper measuring technique with scope and probe depending on the waveform and frequency. Since these are based on experience I cant find a compact info about it.


texts:
I am trying to study the operation of a single plate Induction Hob.

I wanted to use an oscilloscope to measure some of the low voltage digital signals on the microcontroller inside. So I attached the ground lead of the 'scope to a pin labelled 'GND'.

But when I powered up the hob, the fuse inside exploded. I guessed that this is because the GND line is actually bouncing up and down with the AC supply.
Is it possible to use a 'scope to measure signals inside a mains device like this without something exploding or risking damage to the oscilloscope?

I don't have a schematic for this appliance, but it's likely to be pretty similar to most other induction cookers, like this one:

In the top left you can see the AC come in, then there's a bridge rectifier with the negative terminal defined as ground.


texts: The difference in connecting the FB LM2596 before or after the output capacitor

texts:
There is a step-down converter (12V / 5V) based on the LM2596. It has a voltage regulation function based on a tuning resistor.

There should be feedback at the controller output (FB line)

In my example, the feedback line is connected to the output of the inductor.

After the inductor, an output capacitor is connected.

Question:

Is there a difference in connecting FeedBack before or after the output capacitor?

Thank you!


texts: How to use Recom's R-785-0.5 switching DC-DC converters properly?

texts:
For my "prolonging life of old batteries" project I decided to try a switching DC-DC converter. I've got a couple of Recom's R-7805s (datasheet: http://www.recom-international.com/pdf/Innoline/R-78xx-0.5.pdf ), which are capable of 5V at 500mA output. It is choosen over linear regulator, because I want to lose less energy to heat.

However, when connecting 8 old AAA batteries (about 8.6 V) in series to Vin, the converter works fine only with approx. > 100 ohm loads (50 mA current output), and already 50 ohm causes oscillations (I have tried 100, 50 and 10 ohms), because input voltage drops below the minimum. (I am not using blocking diode on the output, if this matters.)

The question is, how can I deduce transfer characteristics of the converter from the datasheet, needed for further circuit analysis? Is my approach somehow flowed, and if not, am I better off with getting values empirically instead of trying to make calculations first?

My current understanding is that at this rate I will need to connect 40 batteries to get at least 250mA, which means I need to add a second converter, because this one is max 34V.

A subquestion I have is how to combine two converters in parallel. My guess is I need blocking diodes to prevent current going back into R-7805. Any hint on this is also welcome.

I have already asked about a different strategy, but I want to try step down approach first, because I need relatively high current.

Also, I do not have a good understanding of internal resistance of old batteries yet. I made some experiments, which showed about 20% of the nominal energy can be had from 1.3V used AA battery (about 500mAh), however, the current should not be too high, certainly not 250 mA. As I am concerned with efficient power transfer, textbooks are recommending matching impedances. I can make more experiments to have some idea of the battery internal resistance, but I'd liked to see if I can get the converter's input/transfer characteristics from specs, regarding input resistance given the 5 V, 250 mA (ideally 5 V 500 mA) DC load.

UPDATE:  Some measurements:

1M (scope's input): 7.8 V input, 5 V output
1k load: 7.4 V input, 5 V output
100 ohm load: 6 V input, 5 V output
47 ohm load: oscillating, hard to measure.

After heavy load, input drops to 7.4-7.6 V and need some time to recover.


texts: I have 4 on/off motors running individually (call them M1, M2, M3, M4) and 4 ping sensors (call them X1, X2, X3, X4) with a board placed in front of the motors and sensors.  As the motors move forward towards the board, I want to keep them all within say 2 inches of each other, so as one motor gets more than 2 inches ahead, I want to turn it off until it's back to within half an inch of the other motors.  Currently, I am looping through all 4 motors, seeing which is the slowest and seeing if the others are ahead by more than 2" and shut the ones that are off, however, I feel like there is a better way to do this since if the "slow motor" changes quickly, it can effect the error calculations, but I'm not sure where to start.  Can anyone give me a better way to solve this loop?


texts: Oops! N-channel Mosfet on sinking output

texts:
I have designed a simple circuit to drive LEDs using a MAX6964 I2C LED driver/GPO chip.  Unfortunately, I somehow missed missed that the outputs are open-drain current-sinking outputs. This is not working because my circuit uses an N-channel mosfet in a low side configuration. From my research on this site, I found a few articles on N-channel and P-channel mosfets but none seem to address my specific question.

From my readings on this site, the N-channel gate needs a positive voltage to switch it.  Again, unfortunately the output of my Max6964 is a current sink not a current source.  I have already made some pc boards with the design that includes surface mount parts. I am trying to "salvage" these pcbs with the smallest possible change of components and/or trace cutting & rewiring.  Here are my thoughts:

Simply replace the the N-channel mosfet with a P-channel mosfet. Is that correct?  My hunch is this will not work.
Leave in the N-channel mosfet and add a pull up resistor (value?) between the gate and the supply (VAA) work? This would invert the logic for turn on the LED but I can live with that.
Since the Max6964 can sink 50mA on each port, remove the N-channel mosfet, jumper the gates to the sources, and increase the value of resistor R6 to some higher value (~100 ohms) to limit the current.  I am trying to maximize the intensity of the LEDs so I am not sure this option is the best.

Here is my circuit:

Here is the simplified Max6964 output port from the data sheet:

[![Max6964 simplified output port][2]][2]

Thanks a bunch in advance for any feedback!

[IMPORTANT EDIT] VAA is +5V PWM signal. So although I liked the pull up idea, I don't think it will work.

[EDIT 2016-04-20 proposed:]


texts: Can i run several links through single pcie x8 connector?

texts: I want to use PCIe with four to eight remote devices, and preferably to avoid PCIe switch. In PCIe connector i can see enough lanes for that, but i definitely don't want to use eight separate cards for that. So one way is to put there a switch, but actually maybe i could just connect to the lanes separately?


texts: Why would a power supply unit with insulating case and galvanic separation need a grounded power cord?

texts:
Recently I witnessed an external IBM laptor power supply that looked like a usual switched-mode power brick (rather small and lightweight for it more than 50 watts power) in plastic case but had a three-wires cable (phase+neutral+ground) between itself and the mains.

Seeing a three-wires cable used with a plastic case switched-mode supply is rather uncommon. Usually either the case is of metal and the cable is with three wires, or the case if of plastic and the cable is with two wires.

Looks like switched-mode power supplies do have galvanic separation. Also the unit had insulating plastic case, so it's impossible that a mains phase wire induces voltage onto the outer surface of the case should there be any kind of short.

What's the reason for a grounded cable in a switched mode power supply with an insulated plastic case?


texts: How to set up load sensor in a full bridge with amplifier?

texts:
I I'm somewhat new to electronics so forgive me for what I don't know.  I'm learning as I go along here.

The overall project is I'm  trying to make a scale connected to an arduino board that will drive a servo.  We have two cats, one who can self feed fine and the other eats all the food.  I want to make a food dish where the lid opens only when the cat is standing on the scale and is within a certain weight range.

I got a used bathroom scale and I am trying to use that for my load cells.  It's the kind with 4 load cells, one in each corner, that each only have three wires and if I understand they are a quarter of the full bridge each.

I've been following a bunch of tutorials to try and figure this out as one one seems to have the complete set up for the scale parts I have.  I started out with this tutorial from Nerd Kit but they use a different type of load sensor, where it's a single load sensor with 4 wires.  As well I'm not particularly sure on the voltage of the capacitor they use or how they really implemented it.  I did buy the voltage amplifier they are using, the AD620.
http://www.nerdkits.com/videos/weighscale/

So hunting around I found a couple tutorials for how to wire up the four load cells into one full bridge, but I have no idea if either even work and I'm not sure how to check.
I have this one here where the guy makes a litter box that tweets him whenever his cats go to the bathroom, so I would assume this is basically the setup I am looking for.  But I can't figure out how to measure the output of it with my multimeter, with or without the amplifier.  I can't ever seem to get a voltage change.

http://www.scottcutler.net/catpoop/catpoop.html

The other is a post from on here, but I am less sure about their setup because I can't tell if they ever got it working.  But I have tried both setups.

Arduino Leonardo + 3 wire Load Cells + INA125P – Analog Signal Bounce / Noise

So first I need to make sure that is actually the way to wire it up  And then I need to know how to correctly amplify it.  I don't quite follow the resistor setup or what exactly that is doing despite trying to read the chip manuals.

I also went and got the LM324 Amplifier while trying to follow this tutorial to see if I had any more luck with the amplifier part.

Anyway, can somebody give me some guidance here?  First is there some way to test my load cells on their own to see if I am getting a change with my multimeter and power applied to it?

Second if my load cell is correct how do I need to wire it up with either of those amplifiers to get an amplified signal out?  Wiring diagrams and drawings would be very helpful at the moment.  Or even better yet a high res picture of some similar set up on a bread board so I can see what part is what.

Thanks in advance to anybody who can help me out some here.


texts: ltspice initial conditions and DC operating point

texts:
Another problem on Lt spice. I would like to know if I use the options uic in transient analysis but I don't specify the .IC (the initials conditions), what IC will use Lt spice for the resolution?

I did that and it ran but I was not able to see a file with DC point information.

Another question? why will a simulation fail to find the dc operating point?


texts: Harmonics modelling in electrical machines

texts:
I am currently working with a permanent magnet synchronous machine and I am trying  to model the harmonics caused by magnetic saturation, dead time, and non linearities of the frequency inverter.

It is known that for a three phase machine, these harmonics have order 1, 5, 7,... (The fifth harmonic is negative sequence and the seventh is positive sequence). Since I already have a Simulink model of the machine, I intend to use the superposition principle to add the harmonics to my current model.

My question is : what is the correct way to model these harmonics? I've checked the literature, and there are some authors that use:

$$
\left\{
     \begin{array}{ll}
            I_a(t) = I_1\cos{(\omega t + \theta_1)} + I_5\cos{(5\omega t + \theta_5)} + I_7\cos{(7\omega t + \theta_7)} \\
            I_b(t) = I_1\cos{(\omega t - \frac{2\pi}{3} + \theta_1)} + I_5\cos{(5\omega t + \frac{2\pi}{3} + \theta_5)} + I_7\cos{(7\omega t - \frac{2\pi}{3} + \theta_7)}  \\
           I_c(t) = I_1\cos{(\omega t + \frac{2\pi}{3} + \theta_1)} + I_5\cos{(5\omega t - \frac{2\pi}{3} + \theta_5)} + I_7\cos{(7\omega t + \frac{2\pi}{3} + \theta_7)}
        \end{array}
    \right.
$$

And others use:

$$
\left\{
     \begin{array}{ll}
            I_a(t) = I_1\cos{(\omega t + \theta_1)} + I_5\cos{(5\omega t + \theta_5)} + I_7\cos{(7\omega t + \theta_7)} \\
            I_b(t) = I_1\cos{(\omega t - \frac{2\pi}{3} + \theta_1)} + I_5\cos{(5\omega t + {\color{red} 5}\frac{2\pi}{3} + \theta_5)} + I_7\cos{(7\omega t - {\color{red} 7}\frac{2\pi}{3} + \theta_7)}  \\
           I_c(t) = I_1\cos{(\omega t + \frac{2\pi}{3} + \theta_1)} + I_5\cos{(5\omega t - {\color{red} 5}\frac{2\pi}{3} + \theta_5)} + I_7\cos{(7\omega t + {\color{red} 7}\frac{2\pi}{3} + \theta_7)}
        \end{array}
    \right.
$$

And others include these harmonics in the voltage.

What is the reason behind multiplying or not the phase displacement (\$2\pi/3\$) by \$n\$ (the harmonics order)?


texts:
Does inductance vary over frequency in passive components.
Consider a Coax cable for example, does the inductance value change as a function of frequency, lets say from 5GHz to 100GHz, does the inductance value ever change?

*My understanding is no, inductor values and capacitor values are not a function of frequency but are a function of their physical character.


texts: Stepper Motor wind turbine AC to DC - what diodes / or rectifier to use?

texts:
I'm building a small wind turbine from this tutorial. It uses Nema 17 stepper motor as the generator.

We need to convert the AC of the motor to DC. The setup is said to be able to produce up to 30V and 1 amp in high wind speeds.

I have 3 questions:

If we were to make our own rectifier from 4 diodes, what size/spec diodes would we use? It says in the comments they used schottky diodes here but I don't know what size they used or what would make sense in this application.
If we were to just use a rectifier, what should we use?
Is there any electrocution danger in this voltage / amps (30v/1 amp) that I need to be aware of? What level of amperage is dangerous?

Thank you!


texts: What is the name the IC package which is SMD version of DIP in the same dimensions?

texts: There is an optocoupler which comes in DIP package. But it also has an SMD version of the DIP package. This SMD package is not SOIC, because its pin pitch size is 100mil instead of 50mil. What is the standard name of this package type?


texts: What's the error in this simulated amplifier circuit?

texts:
I have attempted to simulate (using Circuit Simulator) an IC amplifier circuit (the LM386-3) based on the schematic reference manual. Here is the schematic:

and here is my simulated version:

On the bottom left is the +-400mV input voltage (the 40Hz AC source on the left). In the bottom middle is the output voltage (measured at the output point on the right-hand side). As you can see, the output is not exactly what you might expect from an amplifier. The only difference I can see from the reference diagram is the capacitor and resistor at the two gain terminals but I get a similar output if I remove them. What could be causing the strange stepped output that I am seeing?

You can run the simulation here: http://goo.gl/HNkOfp


texts:
I've made a cooler box for a DSLR to keep it cool while doing long exposure astophotography. It uses 2x 12706 12V 5.8A peltiers which are water cooled.
Peltier spec on amazon says
VMAX 15V
IMAX 6A
QMAX 72W.

The box works really well and I'm able to cool 25 Degrees Celsius below ambient temperature in 15 minutes but I'm seeing something strange.....
When I power the peltiers on, the Voltage drops to around 6-7V drawing around 4A.
I am using an 800w ATX PSU with a 5-60V DC input 20A PWM speed controller to control the temperature. The label on the PSU states a total load of 125A/648W on the 12V rail.

I think I understand from some other reading on here that if the psu cannot deliver enough current it drops the voltage. I'm sure that's a very simplistic way of looking at it but if that is the case. Why am I getting a drop in voltage when the PSU clearly is capable of delivering enough current? Am I missing something obvious?

With nothing connected to the PSU it is giving me 12.2V. With only one peltier connected I get a drop to around 9V.

I have tried connecting one and both of the peltiers directly to the PSU without the PWM controller and get the same readings.
Anyone any ideas please ?


texts: Confusing regarding measuring barrier potential of a pn junction using a voltmeter

texts:
I have been trying to understand why we can't measure the Barrier potential existing in an unbiased pn diode but on seeing the answers I am quite confused.
There seems to be two answers to this question.

1.https://electronics.stackexchange.com/a/256995/56684
Here it says that Schottky effect takes place leading to cancelling of the voltages . This explanation is acceptable to me.

2.https://physics.stackexchange.com/a/86860/62308
Here it is explained by difference in fermi level which also seems reasonable.

Which one of them is the correct explanation?


texts: I need to read a high level logic level betwwen 0 to 30 volts on a microcontroller input, is this is correct, thank you


texts: UPDATE - How to prevent overheating of my ebike system?

texts:
I have a Li-ion battery pack 18650 cells with a BMS, 10 in series by 7 parallel. The pack I bought was defective from day one and had a 7 cell row that got hot when charging now I just repaired the defective row. Now a new problem occurred with overheating everything else. Since one row was defective I never had any problems with overheating but my BMS let me charge the pack anyways till one day it would not charge the pack anymore.
The motor is rated for 36 volts. 350 watts.
The controller I bought has an auto voltage mode 36v or 48v so I wonder if that had something to do with putting too much juice into my motor but not sure.
My ebike controller, wires, and motor overheat when climbing uphill then shuts down, this occurs when the pack is mostly fully charged.
[UPDATE]
Disproven: ( When the pack goes down to exactly 36 volt from discharging I get no overheating goes up hill as it should. When charged the pack reaches 40.2 volts and it heats up with that much voltage.) @35.3 volts it still overheats.
So now I'm trying to find a way to reduce the voltage when the voltage is over 36v. Any suggestions on preventing overheating?


texts:
I’m working on a project were I need to power to some 24V 4-20mA sensors, a 3.3V ESP32 and a 5V SIM808 module.
To accomplish this I’m using a step-down buck converter to reduce a 12V electrolytic battery to 5V and with an LM1117-3.3 feed the ESP32, then I use a step-up buck converter to feed the 4-20mA sensor.
My issue is feeding the 5V SIM808. I tried hooking it up just in the input of the LM1117 but the issue is that when the battery discharges a bit the 5V drops and the module turns off. I thought on adding a LM1117-5.0 that allows an input from 5-12V but since this is battery powered I wanted to see if there is a more energy efficient way.
Any help would be appreciated.
Thanks!


texts:
Trying to determine the transfer function for this Op Amp circuit using the rules that \$V-=V+\$ and that no current flows into the Op amp. I think that \$Vout=IR2\$ and determined the trasnfer function to be

\$TF=(1-R2^2/(Zc+Zr2))/(Zc+Zr2)\$, where \$Zc\$ is impedance of capacitor and \$Zri\$ is the impedance of the respective resistor. This was found using the voltage divider across \$V-\$ to then determine the current

I have been informed that this is incorrect and am unsure where I have gone wrong. Any help is appreciate


texts:
I am thinking to connect PCIe devices to my FPGA board via FMC connector (using a PCIe to FMC adapter).

Will I get full PCIe bandwidth for those devices on the FMC connector?
Not considering FPGA resources right now.


texts: Manually test computer Ethernet port with a multimeter

texts:
I have updated the drivers for the ethernet port an a laptop at home, yet it is only letting 10 mbps through for every cable that is connected, even though Speed/Duplex was set to Dual 1 Gb. I now suspect that the port may have dead pins, so I wanted to see if I can test the pins. If possible, I would like to test with equipment that I already have, such as a multimeter. How can I go about testing this?

Edit:
I should quickly mention that all cables were tested and were working fine with other laptops

Edit 2:
The Ethernet device I have on the laptop is the Realtek GBE Family
Doing some more extensive checks, the Realtek Ethernet Diagnostic utility reports that each pair has a "normal" connection when a cable is plugged in, however pair 4-5 reports "short" when no cable is plugged in, while the other 3 pairs report that they are "open". Manual continuity testing shows that each pair does have continuity between the two pins of each.

@jstola The cables that I have been working with were observed to have download speeds greater than 20 mpbs on various alternate devices. I also attempted to connect the laptop directly to the router with another cable (which was labeled cat 5e and worked the right speed on another device) and there was no such luck there.

No matter what setting Speed & Duplex is set to, it seems to fall back to 10 Mbps (as reported in link speed - under the networking tab in Task Manager)


texts:
I have connected my AVR USART to file stream so as to make it easy to send formatted strings on ATmega8

From the AVR, I can send(TX) just fine. However, I am not receiving anything. Can't put my hand on it but it looks like I'm overlooking something very basic.

uart.c

#define FOSC 8000000
#define BAUD_RATE 38400
#define UBRR_VALUE (uint16_t)(FOSC/16/BAUD_RATE-1)

#include "uart.h"

FILE uart0_str = FDEV_SETUP_STREAM(UARTSendByte, UARTReceiveByte, _FDEV_SETUP_RW);

void UART_INIT(void)
{
    UBRRH = (uint8_t)(UBRR_VALUE>>8); //set UBRR register
    UBRRL = (uint8_t)UBRR_VALUE;
    UCSRC = (1<<URSEL) | (1<<UCSZ1) | (1<<UCSZ0) | (1<<USBS);//set frame format: asynchronous,8data,2 stop,no parity
    UCSRB = (1<<TXEN) | (1<<RXEN) ;
    _delay_ms(10);

    stdin=&uart0_str;
    stdout=&uart0_str;
}

void UART_WRITE_STRING(char* str)
{
    printf("%s",str);

}

int UARTSendByte(char u8data, FILE *stream)
{
    if(u8data=='\n')
    {
        UARTSendByte('\r',stream);
    }
    while(!(UCSRA&(1<<UDRE))){};
    UDR = u8data;
    return 0;
}

int UARTReceiveByte(FILE *stream)
{
    printf("hello1\r");
    UART_WRITE_STRING("hello1\r");
    uint8_t data;
    // Wait for byte to be received
    while(!(UCSRA&(1<<RXC))){};
    data=UDR;
    //echo input data
    UARTSendByte(data,stream);
    // Return received data
    return data;
}

main.c

#include "uart.h"
#include "twi.h"
#include "ds1307.h"

void bootCode(void);

int main (void)
{
    DDRC = 0x01; //set PC0 as output
    PORTC = 0x01; //turn on PC0
    DDRD = 0x02; //PD0 = RXD = INPUT,PD1 = TXD = OUTPUT

    UART_INIT(); //initialize UART
    TWI_INIT(); //initialize TWI

    UART_WRITE_STRING("ANKIT.*****@GMAIL.COM\r");
    UART_WRITE_STRING("JUNE 16, 2014\r");
    UART_WRITE_STRING("####################################\r\r\r\r");

    while(1)
    {

    };
}

When I run this, I get the printed strings, but there is no response whatsoever to the text I input.

when I send the text, ideally it should be echoed back on the terminal + I should also get the "hello1" strings hard-coded in the UARTReceiveByte function

UPDATE

While looking at my code I had another thought.

Since I am binding my USART input and output to the standard file streams => if in order to TX from AVR I need to use "printf". By the same logic, the data entered from my PC terminal will not be valid unless there is a "scanf" call in my code.

So as a test, I added a line in my main.c before the infinite loop

unit8_t d;
scanf("%c",&d);

Now when I enter something at the terminal i do get "hello1" 2 times printed on the terminal (as coded in the UARTReceiveByte function).

As a side question, while I am using FILE streams, can I also use USART interrupts?


texts: Could somebody clarify the phase angle and gain of this transfer function?

texts:
Suppose a circuit with a transfer function of the form \$A(\omega)=\displaystyle\frac{A_0}{1-\frac{j\omega}{\omega_0}}\$ has \$A_0=-10\; V/V\$ and \$\omega_0=100\;rad/sec.\$
We were asked for the gain when \$\omega = \omega_0\$.
My formula for the gain is:
$$ A_{v},dB = 20\log\left|\frac{A_{0}}{ \sqrt{1+(-\frac{ω}{w_{0}})^2}}\right| $$
Hence, at \$\omega = \omega_0\$, the gain should be 16.98dB since
$$ A_{v},dB = 20\log\left|\frac{-10}{ \sqrt{2}}\right| $$
Is that right?
Then next we have to determine the phase at:

\$\omega = \omega_0\$
\$\omega = 1\$;  \$\omega_0=100\; rad/s\$
\$\omega = 100,000\$;  \$\omega_0=100\; rad/s\$

My solution:
$$ phase = \tan^{-1}\left(\frac{\omega}{\omega_{0}}\right)$$
So number 1 would have been 45, number 2 is approximately 0, then number 3 should be 90.
I wasn't able to confirm the other numbers but number 3's  answer is 270. Why is that? So that means the right phase angle is -90?


texts:
I have two stepper motors in parallel on my 3d printer Z axis.
The type of motor is Wantal 2,5A 1,8 deg/step and they are both driven by a Polou driver type A4988.

Since I suspected that the Z axis was loosing steps during printing, I swapped the driver around with the X axis where, while printing, it is much easier to see if steps are loosen, simply looking at the result of the printing while progressing.

I detected that the driver on the X axis (ex Z) was the problem because visibly losses steps (the printing was moving away from the original position).
Now that I have found out that the problem is the driver I also experienced that the one from X now on Z has been damaged.
I think I have a problem on one of the motors on the Z that damage the driver.

How do I check such motors to make sure they are fine without incurring the risk to damage additional drivers?


texts: Velocity showing in GPS-Navigation Systems

texts: How exact is the velocity that is showing in a GPS Navigation System like Navigon or TomTom?


texts: USB data cable that doubles up as a USB storage device

texts:
Is it possible to create an USB to micro USB (or lightning) cable that has storage built into it?

So if it's plugged into a computer with no phone, the computer recognizes it as a regular USB storage device. If it's plugged into a computer with a phone attached, it only acts as a regular USB data cable.

If is possible, is it difficult to do?


texts: How to send data from external device to OS with rs232 and fake it as a mouse

texts: I have a project that i need to send some data with an RS232 to USB cable from external Msp430 launchpad to the computer and fake it as a mouse. Is this possible without learning USB protocols of the mouse?


texts: Two linear regulators from a single buck converter

texts:
I have a switching regulator giving 12V and 5 amperes maximum current,and I have a CW7805 linear regulator IC (5v 1.5A ) at its output. The problem is due to my circuit taking almost 1 amp of current, the power dissipation is almost 7 watts. Even the 2.1x2.5 cm heatsink gets hot.
I cannot lower the switching voltage as I need to drive led strips from the 12 volts.  What are my choices? Can I join the outputs of the two CW7805 ICs and connect them in parallel, or should I just connect both the grounds and power components seperately to share the current between them,
or should I add a 9V linear regulator in between the two so that dissipation is less?
Another thing I wanted to add is that the switching regulator is being powered from a switch mode powersupply, so I imagine adding a third switching regulator (instead of the linear regulator) would probably give some crazy effect on the outputs.


texts: Why are you supposed to wind an electromagnet only one way?

texts:
As I have been researching winding electromagnets, one of the suggestions that came up was to only wind the magnet in one direction - not just as in always spinning the rod one direction, but as in winding down the rod, then to wind the second coil by running the wire back up the coil parallel to the rod and then taping over and winding back down in the same direction (as described here). I'm reasonably sure that this is not just my misreading since my physics teacher also remembered a similar instruction for building strong electromagnets.

Why is this? I can't think of any explanation since it seems to me that as long as the rod is not rotated in the opposite direction while winding, the electricity will be flowing in approximately the same direction around the rod, therefore generating aligned magnetic fields.


texts: Noncoherant demodulation of minimum-shift-keying (MSK) signal

texts:
The book "Digital Modulation Techniques" by Fuqin Xiong writes:

Since MSK is a type of FSK, it can be demodulated noncoherently with
about 1 dB asymptotic loss in power efficiency.  The demodulated
sequence is \$\{d_k\} \$, which can be converted back to the original
data \$ \{a_k \} \$ by the decoding rule \$ a_k = d_k \oplus d_{k+1}\$.

Can someone share some insight on why this technique works? Does it apply
to any noncoherent FSK demodulator?


texts: Bug in Keil ARM compiler with interrupt handlers and C++?

texts:
I have a problem with writing interrupt handlers in Keil ARM compiler for LPC1114. When I write program in C++ and specify --cpp compiler option all code from interrupt handlers disappears, it is replaced with infinite loop. I wrote simple program that illustrates my trouble.

#include "LPC11xx.h"           // LPC11xx definitions
#define SYSTICK_DELAY 120000   // for 10 ms systick @ 12MHz osc

void SysTick_Handler(void)
{
  __NOP();
}

int main (void)
{
  SystemInit();                   // from system_LPC11xx.c
  SysTick_Config(SYSTICK_DELAY);  // from core_cm0.h
  // Loop forever
  while (1) __NOP();
}

When trying to compile this code with --cpp compiler option I get infinite loop in disasm:

SysTick_Handler PROC
            EXPORT  SysTick_Handler           [WEAK]
            B       .
            ENDP

This is the place where __NOP() from above program must be. And it is there when I'm compiling code with --c99 compiler option or without additional options. Keil MDK version is 4.12. Can anyone tell me is there any solution or workaround ?


texts:
Sorry about the novice question.

At the moment I am using an op-amp (http://www.ti.com/lit/ds/symlink/lm224-n.pdf) to boost my analog load gauge sensor output.

The op-amp takes two inputs and gives one output.

If I wanted to remove the op-amp from my circuit, my sensor still has two outputs (-, +) but the next component (an ADC) in my circuit only has one input.

Is it possible to remove the op-amp and somehow connect my two wire sensor straight to my one wire ADC?
(involving zero new components if it can be helped)

Edit:

I was using two different load gauge, both with four wires, like this:

1) http://www.cnloadcell.com/uploads/20167365/r201612261601227200949.pdf

2 ) https://images-na.ssl-images-amazon.com/images/I/61EL9dNvYlL.SL1200.jpg
 https://www.amazon.co.uk/gp/product/B01CBGHCD8
 (sorry no datasheet)

And this is the ADC:
 https://www.mouser.co.uk/ds/2/405/ads1015-438945.pdf

Yes this ADC does have differential input (2 pins) but this would mean I could only attach two sensors per board but I'd like to have four per board.

The load gauge sensor and the ADC are both powered and grounded by a Raspberry Pi.


texts: ESP8266 controlling RC car. Voltage drop, ESP shuts down when I increase motor speed

texts:
I am preparing remotely controlled RC car using Android phone and ESP in TCP client/server configuration. I power it using 4x AA 1.2V batteries (2500mAh). The problem occurs when I try to accelerate with more power (max PWM on L293D). ESP-12's LED dims till it shuts down. When I use small PWM rate, I get only dimming, but car works ok.

Some more info:

When in idle state - with smartphone connected, ESP has 3.15V. Moving servo lowers it to 3.14, but when I start moving motor with bigger PWM there is a drop even to 2.3V.
My motor takes even about 1.4A when it is connected directly to my 4 batteries (5.3V). When using L293D motor has about 0.45A,
I am aware that L293D is only capable of giving me 600mA on one channel, but thats why I used bridged configuration (not a big improvement, but it is a little better). But this small output current makes me even more sure, that L293D is quite 'weak' and should not take all energy thats in the circuit.

Here's what I've already tried:

Adding capacitors between Vcc & GND of ESP, to give it some energy in 'hard times' - it has really small impact.
Using not bridged cofiguration of LD293 in the case if L293 drains 2x more current or is somehow 'overpowered' (this configuration provided below is bridged - I connect inputs and outputs of 2 channels together - as far as I know it is ok)
Getting rid of voltage regulator - I connected ESP directly to 3 of 4 of my accumulators (3,90V without a diode, 3,71V with a diode). The same dimming.

Please advise. Maybe I lack some capacitors or protection from noises? I thought about ordering L298, but considering that probably I have to small power efficiency, ordering IC that has bigger output current is not really reasonable.


texts: What do these two PNP transistors do in this power circuit?

texts:
I am a beginner in circuit design and I have been trying to understand the purpose of the Q2A and Q2B transistors in the above power circuit.
Here is what I am able to understand so far.

There are two power sources, +5V and +5V_USB.
When +5V is present, the Q2B turns on which turns of the P-Channel Q1 and vice versa
This makes sure that only one source is available at the same time?


texts: High side current sensing using differential amplifier

texts:
I would like to measure current making use of a shunt. Since the solution needs to be scalable I wanted to have a circuit that would be easily adjustable to various current ranges, and therefor opted to make use of a differential amplifier. It's also necesarry to measure on the high side, since there are a lot of components connected to common groud, which I dont want to disturb.

For my first test I wanted to measure currents up to 30Amps, neatly scaled to my 8bit 0-3v ADC(Not the best resolution, but plenty for my application)

I did some online searching, and came across this simple circuit a lot. I calculated the resistor values to get a gain of 40, so the 75mV voltage drop at 30 amps through the shunt would get me 3V at the output of the op-amp.

However when I want to measure current on the high side of my circuit, I dont get the values I expect. When I put it at the low side it does work however. I'm in the dark on what's wrong with this circuit.


texts: How can I collect data from a hydrophone?

texts:
I want to collect data from a hydrophone over a period of days or weeks. A desired typical collection period would be 30 days.

Hydrophones are a piezo-electric transducer that output millivolts (thousandths of a volt). A response from a hydrophone might vary from 0.001 Volt to 0.099 Volt, for example. The needed sampling rate is about 10 kHz. I want to avoid doing anything that would distort the signal. Signal purity is very important. I want to attach the recording mechanism right to the hydrophone in a water-tight box. I can make the housing, but I do not know how to record the data, or what could be used to record and digitize such a low voltage signal.

In general, the goal is to to collect and digitize the low voltage signal as purely as possible, minimizing any noise or distortion. Non-linearity in the hydrophone output is not an issue because I have calibration curves for the hydrophone that describe its frequency response in great detail. So, the data can be adjusted after the fact to equalize for the variations in sensor sensitivity.

The signals of interest are primarily between 30 Hz and 500 Hz. Signals between 500 Hz and 6000 Hz are interesting, but are of secondary importance, so if the system design would benefit significantly by ignoring them, then that is ok.

Cost for components I am hoping for would be less than $1500 (not including the hydrophone, battery and other stuff). In other words, the budget just for signal processing components and data storage would be $1500.


texts:
I'm an Electrical Engineering student and I'm studying the hardware description language known as VHDL.
I searched for it on Google looking for an IDE (I'm on a mac), but this language seems pretty dead.

So here is my question: in my future job as an electrical engineer will VHDL be useful to me? Are you using it?

UPDATE: Thank you everyone for the answers, I was clearly wrong with my first impression.


texts: Need help repairing adjustable DC power supply stuck on 48V

texts:
I have a cheap benchtop dual-output adjustable DC power supply. One of the outputs is working alright, the other one "burned out" when it was left loaded somewhere near 80% of its maximum for 24 hours.

After opening it up and taking a look, I found a few burned power resistors (0.5Ω rated for 5W) plus some resistors which were surprisingly still functional (though burned beyond recognition) sandwiched between/around them, all of which I replaced:

Before:

After (with 3 resistors in parallel to give me an equivalent circuit until the replacement power resistor arrives - they haven't burned out in testing, so I'm good for now):

When these power resistors went out, they took a few more resistors nearer to the middle of the board out with them, and I replaced those as well. Powering up the board burned the regular resistors in the middle again, so I replaced them once more and tested all the other components on the board:

Luckily for me, there are two identical halves of the device, and I was able to quickly compare resistance across components leads (disconnecting some where I wasn't sure, but not all of them) and don't seem to have any remaining bad components. None of the capacitors are visibly damaged and their basic functionality checks out (though I'm unable to test their compliance to their rated capacitance as at 470uF they are out of my DMM's range and I don't have an ESR). The diodes seem to check out (though I'm having trouble positively testing some of the high-voltage protection diodes). The rectifiers have tested OK, and none of the transistors are shorted out so far as I can tell.

Crucially, I'm not sure what failed components would result in this behavior. The power supply is actually advertised as being 0-30V (and 0-5A), the 48V it's giving out now are well out of spec.

The problem is much complicated by the fact that the PCB design is an absolute mess. A number of traces appear to have been (by comparison to the other, functioning board) purposely joined together via globs of solder. The solder obviously reflowed around the burned power resistors and possibly in a few other places, but tracing it as best as I could and comparing it to the other board, it seems that everything is fine (and the burned traces are still functional).

The unit is still stuck at 48 volts no matter how I adjust the pots (and I tested them, just in case it was ironically just a control problem after everything I did and tested - I also disconnected the control and output boards entirely to no effect), and I'm not sure what else to try. I'm not very well-versed in analog, though I've tried isolating the problem as much as I could only to always end up disproving my hypotheses.

Here's the board now:

The unit itself:

I found a few schematics online for similar Chinese units, but I haven't been able to find any that match one-for-one my unit.

EDIT

The power transistors up close:


texts:
Does the AM26C32 leave outputs floating, by which I mean, when "off", is the output pulled to GND, or would I need to provide a pull-up/down resistor?

Where in the datasheet would this info be specified?


texts: I have been testing a couple of BFY50 transistors that I salvaged using my multimeter. One of them reports an hFE of ~109 (this looks consistent with the data sheet value of 112). The multimeter reports a value of ~470 for the other. Is this an indication that the transistor is damaged?


texts: I've been thinking about the skin effect and that got me thinking: When high frequency current goes through a superconductor, does it still radiate off like it would with copper?


texts: Transformer secondary wired to primary and secondary of second transformer

texts:
simulate this circuit – Schematic created using CircuitLab

I see something like this for ethernet, and it confuses me. What is it for? What does it do? Could I remove that from the schematic?


texts: Function of Specific Capacitor in Audio Amplifier's Negative Feedback

texts:
The audio amplifier that I am referring to here consists of three stages. Among others, the amplifier also includes negative feedback (NFB) that is made of two passive resistors.

From the base of TR3 to ground, there is a NFB's resistor connected in series with capacitor C2 (referring to red square). What is the function of that capacitor in such circuit?

I know that this RC circuit in series represents a filter and limits the amplifier's gain bandwidth at lower frequencies. It obviously represents some kind of barrier to an audio amplifier. So, why wouldn't I just short it to ground? This would be most probably seen as improved amplifier's gain bandwidth.

Why did the first creators of such circuit topology put it there? With what purpose?

I don't see any, unless shorting that capacitor to ground and leaving only the resistor RF2 represents another biasing source for TR3's base, whereas RF1 is already biasing source for TR3's base. So, that would probably have some other effect.


texts: Problem designing a beacon light circuit

texts: I am designing a beacon light base on this multivibrator circuit. It should give out a burst of very bright light to a 1W led in about 100ms for every few seconds. I have tested this circuit in a breadboard. it worked fine, but I also wanted to add a LDR to it, so that it only operates in the dark. This was the part that I was having trouble with the breadboard. So I tested the circuit in Tina-Ti simulator, and the transient also gave me weird results. I have no idea what went wrong. is there any faults in this circuit? and where should I put this LDR? I have tried putting it in between base of T2 and ground, and it worked for a while. But it totally stopped oscillating when I shine a flashlight on the LDR.


texts: Weakest link in lifetime of electronic circuits

texts:
I'm working on a product, a single-board computer with an expected lifetime of 10-15 years, and I'm trying to identify the correct components to focus on for this. So far electrolytic capacitors appear to be the weakest and most obvious link, but I'm finding it hard to estimate how well switch-mode converters (ICs) will survive at elevated temperatures for example. At the maximum ambient temperature I'm seeing some of the ICs approaching their maximum operating temperature. Can I possibly assume that while the ICs are within specifications they'll likely function well for years to come on average?

Should I hence focus solely on specifying the electrolytic capacitors for this lifetime and maximum expected temperatures and assume the ICs and resistors will be of little concern?

The product has been designed with low self heating in mind, low-power DDR3 memories, synchronous step-down converters, and omission of all linear regulators. The board itself however is enclosed in a 100% waterproof metal enclosure (HMI) which can not contain air vents or complex dissipating surfaces for cleaning reasons. Hence in extreme cases with ambient temperatures of 40 degrees celcius it gets hot inside the enclosure and parts need to withstand elevated temperatures.


texts: Splitting power to two devices (Raspberry Pi & LED Matrix)

texts:
I am working on a small project involving a Raspberry Pi and an LED matrix.
Both devices are rated for 5V but requiring different current (approximately 2A for the Pi and 4A for the LED matrix).
Basically I am following this tutorial: https://www.youtube.com/watch?v=g7Zrnr4kGw8&t=186s
except that I only have one LED panel, whereas he has two.
I would like to only have one power supply for both devices.
Could this be achieved by simply splitting the output from a 5V 6A power supply, say, to both devices?
Assuming that I have enough current for both devices, are there any other issues that could arise from connecting the devices like this?

simulate this circuit – Schematic created using CircuitLab
Apologies for the poor schematic.
Many thanks,


texts: What is the output voltage of this diode circuit?

texts:
Given the following ideal diode circuit:

I would like to find the output voltage measured on the wires on the right. The ac source Vs on the left is given as:

$$Vs=8\sin{wt}$$

Here is  my attempt at a solution:

Let's suppose that the diode is on, so it represents a short circuit and the voltage measured on the wires is 2Volts. In this case the current of the loop (clockwise direction) is given by:

$$I=\frac{V_s-2}{1000}$$ Knowing that the current can't flow from the cathode to the anode, this equation is valid only if Vs is greater than 2. Otherwise, the output voltage is equal to Vs since the diode represents an open circuit.

In total:

$$V_{out}=2, Vs>2$$
$$V_{out}=Vs, Vs<2$$

Since I haven't touched on these problems for a while, I'm not so sure about the result as well as my approach to the problem. Is my solution correct? Is my approach with the current equation good for such problems?


texts: Arduino + relays + multiple magnetic locks

texts:
I'm new here.

I saw some examples on how to connect an Arduino to a relay to switch on a magnetic lock.

What if I have 30 magnetic locks. Does it mean that I need to have 30 relays as well? If I need 30 relays, will I have sufficient GPIO port on the Arduino connect the 30 relays? Any samples to refer to?


texts: Why Led lights with 3 AA batteries and not in pairs?

texts:
Im trying to purchase some lamp powered by batteries, I want to use the typical 2100 mAh AA rechargeable 1.2V batteries to avoid purchasing tons and tons of one use AA simple batteries.

I already have an old lantern working with 4 AA 1.2V batteries, not led, I can use a 4 pack rechargeable batteries, but it seems that it consumes the power even if its not turned on, so I decided to get some new led wall lantern or something like those closet lights on amazon.

But there seems not to be any of those lights out there powered by a pair number of AA batteries (2 or 4 batteries), every light is 3 AA, 6 AA, and more and more 3 AA powered.

Why always are 3? I can't use rechargeable batteries on that because when I can't recharge 3 at same time, and if I try to recharge those 3 used batteries with a 4th already charged battery, then it does not charge properly.

IS the "industry" doing this only to force people to buy tons of simple AA batteries or is there any specific electronics issue with pair powered batteries on leds?


texts:
I'm trying to do home automation using android app and arduino teleduino.

Basically, I'll be doing lights and power plugs.

I still cant post images so here' the link to the diagram I saw and will be using.

light bulbs OK, but when it comes to the plugs, having appliances connected to them and suddenly switching it on will just destroy my things ruining my power supplies.

How am I to do this safely for my appliance?  Please help me with a diagram and samples.


texts: What is this four-legged part from under an inkjet printer head?

texts:
I've disassembled the print head of an old dried-out printer (EPSON Stylus Photo R300) and found a very small part under it, next to the surface with the nozzles. It's 4 mm long, 3 mm wide and 2.5 mm tall. Here's how it looks from its top (the side farther from the PCB):

And here's how it looks from the bottom (the side adjacent to the PCB):

In the actual print head it was mounted at the bottom, as if "looking" at the paper. This part seems to look like a pair of IR receivers/transmitters, but the two appear very similar, and I'm not sure why the printer would try to "look" at the paper.

It's definitely not an optical encoder commonly used to track head position, since that one I've already found and identified, and the part in question was quite far from the striped tape.

So what is this device, and what is its role under the print head?

EDIT in response to the answer: I've tried supplying some power to the device, and indeed one of them appears to be IR LED:


texts:
I want to control an industrial motor rate valve that accepts a 4-20mA input.
I want to use an Arduino Uno as the controller of such a device but I do not know how to generate such a signal from an Arduino.
I have done some research and found out that there is no definite way to do this. Instead, some analogue circuitry must be designed.
Can anyone help me get started with this? Thank you so much.


texts: Precision Power Supply / Elektor, December, 1982

texts:
Since this PSU was published by Elektor I assume that some of you might heard or read about this project.

http://www.retro.co.za/zs1ke/projects/PrecisionPowerSupply/PrecisionPSU-Elektor-Dec-1982.pdf

This PSU is capable of delivering from 0-33V at 3A. Its voltage is stabilized, can be regulated and has current limiting control + short-circuit protection.

This is also my final school project. I made two of these PSU's in one housing.
First one works perfectly fine. But second one causes a problem on the output that couldn't been solved yet.

Me and my mentor (professor) did all kinds of measuring on the not-working PSU - measuring connections, short circuit possibilities, voltage measurement on specified components and with oscilloscope too.

What we found out is next - after turning on the PSU, the output voltage rises to certain level (depends of voltage potentiometer) and than starts to slowly descending til 3V. Then the voltage changes slowly from 3V-5V. When we measured the Op-amps and LM723, on certain pins there was voltage also slowly changing.
And if I connect load on the output the voltage slowly descends till 0V (everything seems like there should be a capacitor making these problems)

I changed Op-amp, LM723 and a few capacitors (every of them but smoothing capacitor - my professor said that it wouldn't be making such problems).

*Capacitors are older ones (but not used yet), all other components are new (smoothing capacitor too - the big one).

I also invested a lot of money and time into it and I don't want to end like this (with only half of it working - I made two in one with separated transformer stages so I can get negative voltage from +33V to -33V).

I hope someone has any ideas or has worked on similar project so I can solve my problem (which stayed unsolved till now).

All of these measurements were measured to the common GND of circuit in that part of circuit (stabilizer stage).
This stage has a transformer source of 10V/0/10V (TR1). TR2 is power stage of 26V.

NOT-WORKING PCB

C1= 10,7V (it should be more(Uin times square root of two))

C2= 10,7V (-||-)

C3= fluctuates around 9V

C4(IC1/pin 13)= fluctuates around 10V

C5= fluctuates around 9V

C6(R7)= fluctuates around 5V

C7(IC2/pin 6)= fluctuates around 8V

C8(R14)= fluctuates around 8V

C9= fluctuates around 8V

C10(*to GND of power stage)=  35,5V

C11(R23)= fluctuates around 9V

IC1(stabilizer):

1= 0V

2= 9,6V-9,8V

3= same

4= same

5= same

6= same

7= 8,8V-9V

8= 0V

9= 4,7V-4,8V

10= 9,6V-9,8V

11= 10,7V

12= same

13= 10,6V-10,8V

14= 0V

IC2(op-amp):

1= 10,8V

2= 7,2V-7,5V

3= 5,3V-6V

4= 10,8V

5= same

6= 7V-9V

7= 10,6V-10,8V

8= 0V

IC3(op-amp):

1= 10,8V

2= 8,8V-9V

3= same

4= 10,8V

5= same

6= 10,3V

7= 10,8V

8= 0V

WORKING PCB

C1= 13V

C2= 13V

C3= 7,2V

C4(IC1/pin 13)=7,3V

C5= 7,3V

C6(R7)= 35V

C7(IC2/pin 6)= 12,5V

C8(R14)= 0,15V

C9= 0,15V

C10(*to GND of power stage)=  35,5V

C11(R23)= 0,15V

IC1(stabilizer):

1= 0V

2= 7,3V

3= same

4= same

5= same

6= same

7= 0V

8= 0V

9= 1,2V

10= 7,3V

11= 13V

12= same

13= 8,6V

14= 0V

IC2(op-amp):

1= 13,1V

2= 0,04V

3= 0,43V

4= 13,3V

5= 13,1V

6= 12,5V

7= 13,1V

8= 0V

IC3(op-amp):

1= 0V

2= 0,15V

3= 0,5V

4= 13,1V

5= same

6= 12,4V

7= 13,1V

8= 0V


texts:
I am developing an audio device that will have a mono audio output. I currently use the PCM5102A stereo DAC in my prototype as it is easy to find as a separate module. But it does have a stereo output, which means I have one extra, unused channel. What is the best way to solve this problem?

Use only one channel from a stereo DAC
Combine two channels into one. How?
Switch to a different DAC.


texts: Keil Error: Not a genuine ST Device! Abort connection

texts:
I am using ST-link V2 for programming/ debugging my STM32F103C8t MCU using Keil.
So the problem is that when I try to program the STM32 controller it shows a popup error Not a genuine ST Device! Abort connection
And Keil is not programming the controller. So I have tried different software.
STM32 Cube programmer is detecting my controller successfully with the same ST-link and also have successfully uploaded the compiled hex file from the Keil using STM32 cube programmer and it's working.
Also, I have tried it with ST-Link utility and it also detects successfully and also uploaded the program perfectly. So I think my ST-link V2 and controller are working fine.
But there is some setting I am missing in Keil so after a lot of searching in different forms I have tried the following things that did not help.

Have changed debug setting for connect with pre reset option.

Have tried different frequencies and right now I am low to 10Mhz.

Adding my Keil debugger setting snap if help to figure out what's going on. I am able to program my controller with different software but not with Keil. Any help will be appreciable as it's making me mad each time compiling code in Keil and for testing going to different software for uploading and the main thing I have to trick the Keil for false uploading to get inside debugging mode.
Thank you in advance for your help.


texts: How can I protect a picoammeter or a picoscope in HVDC measurements?

texts:
I'm trying to measure the leakage current along an insulator energize with HVDC (the effect of space charges is been considered).

Can I connect a picoammeter to the ground electrode? If yes, please how do I protect the picoammeter so as not to damage it?

Or

Can I connect a voltage divider (with 5kohms and 50ohms connected in series) at the ground electrode, measure the voltage across the 50ohms with a picoscope and from there I can use V=IR to get my current? If yes, please how do I protect the picoscope from getting damaged?


texts: Atmega32u - Ground in bus powered configuration

texts: The Datasheet provies an example configuration for when the device is powered from the bus, and shows the bus Vss connected to UGND on the avr micro, but shows a connection to earth/ground on the other GND pins. Where is this ground coming from/connected to? The usb shield connection? Tied to bus' Vss?


texts: Forgot to put a via near bypass capacitor, and now the boards have been fab'd - what can I do?

texts:
I goofed and didn't notice this until the board was already fab'd and assembled. The board is an RF amplifier; the portion I have pictured is a part of the DC control pat (so no RF is nearby but we're talking 100MHz-1GHz so it's surely floating everywhere). See the possibly disastrous screenshot marked by 'missing a via here'. (The fab removed by hand the huge trace to nowhere, before anyone asks). I really need to be more careful with altium's polygon pours...

I'm really kicking myself right now about this stupid error, it's a 20 board run and money is really tight; I'm in academia, so these boards are not getting remade. The problem is C18 is a 100nF bypass cap for a high speed op-amp. It seems to me that without a via to the ground plane, theres only that ultra tiny slice of the pour connecting it to a via 'very far' away. I might be wrong, but from everything I've read, the cap might as well not even be there because the inductance will be so large. I don't have the boards back yet, so the fab might even have eliminated that small trace entirely! It's only a few mils thick.

Maybe I'm being overly worried, as I don't yet know if this will cause issues. But is there anything I can do 'by hand' to improve the decoupling? Would soldering a small wire to ground be effective? I guess my main concern is oscillation with RF signal floating around everywhere; the op amp I'm decoupling is the LME49990, and I've seen this thing oscillate when bypass caps arent placed right.


texts: Find the total gain from the following Signal Flow Graph

texts: The signal flow graph for a system is given in the figure. Find resultant gain.


texts:
I'm trying to understand how to derive the BEP for 8PSK by geometrically looking at the decision regions.

Say I have this 8PSK signal set and the corresponding decision boundaries.

I assume that '000' is sent, and I want to calculate the BEP. So I have

$$P_b(e) = \frac{1}{3}(1 \times R_1 + 1 \times R_2 + 2 \times R_3 + 1 \times R_4 + 2 \times R_5 + 2 \times R_6 + 3 \times R_7)$$

Since \$R_1 = R_4\$, \$R_3 = R_5\$ and \$R_2 = R_7\$ by symmetry, the above can be simplified to

$$P_b(e) = \frac{2}{3}(R_1 + 2R_2 + 2R_3 + R_6)$$

Then we have

$$R_1 + R_2 + R_3 + R_6 = P\Big(n > d_1sin\frac{\pi}{8}\Big)\tag{1}$$

and

$$R_2 + R_3 = P\Big(n_0 > d_1sin\frac{3\pi}{8}\Big) \times P\Big(n_1 < d_1sin\frac{\pi}{8}\Big)\tag{2}$$

I'm having a hard time visualizing and understanding how \$(1)\$ and \$(2)\$ are obtained.

I understand that \$n\$ is the noise vector, and \$n_0\$ and \$n_1\$ are the horizontal and vertical components of the noise vector, and we are trying to find out how far \$n\$ or \$n_0\$ and \$n_1\$ will go to "push" the signal into the wrong decision region.

I've seen the following from this website, and it seems to explain \$(1)\$, that is, the noise vector \$n\$ "pushes" the signal past the decision line (DL) into the wrong decision regions \$R_1 + R_2 + R_3 + R_6\$.

But what about \$(2)\$? I don't know why we have \$sin\frac{3\pi}{8}\$ and \$sin\frac{\pi}{8}\$.

Also, is the noise vector always perpendicular to the decision boundaries?


texts: lighting halogen 110VAC transformers to 12 VAC, 150W

texts:
I have lighting fixture that has two lighting halogen transformers 110VAC, 60Hz
to 12VAC and 150W each in something like circular box. Their inputs are connected in parallel.

Their outputs are 12VAC, and they are not interconnected, each has its own load of several halogen bulbs.

They are connected in parallel configuration on primary sides. I am planing to take it to Europe and I will have there 220VAC input, 50Hz.
May I connect these transformers in serial configuration, so then having 220VAC across both transformers in serial connection on primary side, I will have each transformers exposed to 110VAC,  am I right. I know although they are the same type, they are not identical. I know that with 50Hz the transformers will not have enough core for that frequency, so possible some humming noise, right?

Then leave secondary side as is, I think I will be fine.
What you think if any problem with that configuration?

Regards,
Safet


texts: How is it possible that the reverse transfer capacitance of this FET is so low?

texts:
A FET has parasitic capacitance, which can be modeled as a capacitor between each of its terminals (gate, drain and source), which I refer to as Cgd, Cgs and Cds, as shown in the image below.

FET manufacturers list other capacitances in their datasheets, which are refered to as input capacitance Ciss, output capacitance Coss and reverse transfer (or Miller) capacitance Crss.
As far as I know, these capacitances are measured as follows:

Ciss is measured by shorting drain and source, so it really is the parallel capacitances Cgd and Cgs, hence: Ciss = Cgd + Cgs
Coss is measured by shorting gate and source, thus it is Coss = Cgd + Cds
Crss is measured between gate and drain (without shorting anything), therefore it is Cgd plus the series capacitance of Cgs and Cds:
Crss = Cgd + 1 / (1/Cgs + 1/Cds)

However, when I take a look at the datasheet of an AO3162, there is something strange: this device has typical values of Ciss = 4.2 pF, Coss = 0.45 pF and Crss = 0.05 pF.

Cgd must be very small, so I approximate Cgs = Ciss and Cds = Coss. However, the series capacitance of these is 0.41 pF, much larger than the measured value for Crss. How is this possible?


texts: Is there a way of measuring components in circuit?

texts:
I have some old circuit boards full of SMD components that I would like to reuse in my projects. Before going through the trouble of removing any from their old circuits, I would like to know if they are of any value to me by measuring their resistances and capacitances for example. But simply using a multimeter and probing the terminals of one component like a resistor would give the parallel resistance between all paths from one terminal of the resistor to another, not just the resistance of the one component across which I have connected my multimeter.

Is there any way to measure single components without removing them from their circuit boards?


texts:
I have seen conflicting sources about ground plane design.

I have been told at my work many times, just slap a single massive ground plane in and that works well enough, we don't deal with anything that high frequency anyway.

Yet, I look at SMPS datasheets using clocks in the MHz range and they all show intricate designs for ground layout.

My question is, where do you draw the line between using a single plane in vs designing the ground planes? For example, when frequency is above a certain threshold, or a certain amount of sensitivity is needed, or a specific amount of power being dumped to ground?

And typically what sort of benefits does split ground give you over a single? Less noise? more stable?


texts: Spurious Ouputs from Nexperia 74HC154 4 to 16 Decoder/Demultiplexer

texts:
Problem:
Driving 74HC154 Decode with Atmega328 using Arduino software.
Decoder Outputs Y0 – Y10 (pins 1 – 11) seem to be picking up signals from each other.
The outputs are not random noise.  Changing which output pins are being turned on changes which output pins have the spurious output signal.  This is occurring with the 74HC154 outputs not connected to a circuit and also when connected to an LED array.   Since 74HC154 is being used to turn PNP transistors on and off, the spurious signals are incorrectly turning on PNP transistors.

Test Setup:
Breadboard with Atmega328 running Arduino software.

Nexperia 74HC154 Pinout and 74HC154 Truth Table

Example 1:
Arduino Code:

//Inputs into 74HC154 pins 20-23

int InputA0 = 4;

int InputA1 = 5;

int InputA2 = 2;

int InputA3 = 3;

void setup()

{

pinMode(InputA0, OUTPUT);

pinMode(InputA1, OUTPUT);

pinMode(InputA2, OUTPUT);

pinMode(InputA3, OUTPUT);

}

void loop()

{

//Output Y0

digitalWrite(InputA0, LOW);

digitalWrite(InputA1, LOW);

digitalWrite(InputA2, LOW);

digitalWrite(InputA3, LOW);

delay(1);

//Output Y7

digitalWrite(InputA0, HIGH);

digitalWrite(InputA1, HIGH);

digitalWrite(InputA2, HIGH);

digitalWrite(InputA3, LOW);

delay(1);

}

Outputs Y0 and Y7 look great.  Output Y6 should be off, but has 5 volt short  spikes/bursts.  These spikes seem to line up with Y0 and Y7 transitions from High to Low. Same with Y3 and Y4 - Spikes..why?

Outputs Y2 and Y5 are off as they should be with no spikes.

Outputs with spikes: Y1, Y3, Y4, Y6,
Outputs without spikes: Y2, Y5, Y8, Y9, Y10

Now the interesting part:

Example 2:

Turn off Y0 and turn on  only Y1 and Y7

//Output Y1

digitalWrite(InputA0, HIGH);

digitalWrite(InputA1, LOW);

digitalWrite(InputA2, LOW);

digitalWrite(InputA3, LOW);

delay(1);

//Output Y7

digitalWrite(InputA0, HIGH);

digitalWrite(InputA1, HIGH);

digitalWrite(InputA2, HIGH);

digitalWrite(InputA3, LOW);

delay(1);

Spikes now on: Y3, Y5

No spikes on: Y0, Y2, Y4, Y6, Y8, Y9, Y10

So Y3 kept the spikes, and spikes went away on Y4 and Y6.
Y5 which had no spikes, now has spikes.

Finally, this one may have a clue in it.

Example 3:

Turn on only Y4, Y7 and Y8

//Output Y4

digitalWrite(InputA0, LOW);

digitalWrite(InputA1, LOW);

digitalWrite(InputA2, HIGH);

digitalWrite(InputA3, LOW);

delay(1);

//Output Y7

digitalWrite(InputA0, HIGH);

digitalWrite(InputA1, HIGH);

digitalWrite(InputA2, HIGH);

digitalWrite(InputA3, LOW);

delay(1);

//Output Y8

digitalWrite(InputA0, LOW);

digitalWrite(InputA1, LOW);

digitalWrite(InputA2, LOW);

digitalWrite(InputA3, HIGH);

delay(1);

The clue is that spikes appear in Y4 only when BOTH Y7 and Y8 are also on.

Y4 does not have spikes if only Y7 OR Y8 are on:

Spikes appear to be related to internal switching within 74HC154.

Question:  Are these spikes internal to the chip?  Is there any way to eliminate them?

Is this an issue with the Nexperia 74HC154?


texts: Mixing two signals without affecting output bias point?

texts:
I want to mix together two signals. The signals have a DC bias but i'm only interested in the AC portion. Capacitors C1 and C2 are used to strip out the DC from the input. Potentiometers R1 and R2 can be used to attenuate the signals independently. OpAmp U1 then combines the signals as an inverting summer. The OpAmp has a bias at half battery voltage so that it can produce AC with a single rail supply. The DC bias of the OpAmp is stripped out with C3. The input signal is between 100Hz and 40kHz.

The problem i'm having is that the potentiometers affect the DC bias of the OpAmp.

How can I modify this circuit so that the potentiometers don't affect the bias point of the OpAmp?

My best guess is to place capacitors between the potentiometers and the summing resistors.

simulate this circuit – Schematic created using CircuitLab


texts: RnD on an EEG, Help required, what op-amp?

texts:
this is my first post, and I need some help/advice finding the right integrated circuits.
I'll start by describing the project background a bit. I've received a fellowship to develop an open source electroencephalograph, the finished hardware will provide a platform for people to develop various creative and therapeutic uses for an EEG system i.e music controllers, game controllers or brain training programs.
I want to use an Atmel MCU for the analogue to digital conversion, I'd like it to connect to a computer via USB and I'd also like the unit to be powered by the USB connection.
I need help finding a suitable op-amp IC to amplify the signals from the electrodes prior to the MCU. The finished device will be 16 channels, so I'd like to find an IC with multiple op-amps. The electrical activity picked up by the electrodes will be in the region of 200mV and less, so I'll need a lot of gain.
Is it possible to adjust the gain of an op-amp circuit with an MCU by using a digital resistor program? It would be nice if the hardware could be reprogrammed to work with various audio and sensor inputs.
Any help or advice would be fantastic.

Jim.


texts: Does DC DC switching converter needs pot readjusting on input voltage change?

texts:
I have adjusted my LM2596 regulator to 5V output with 16V input. I'm about to change the input to 25V. Will my 5v output stay the same or do I need to adjust the pot again ?

I can't easily test myself because my circuit would need unsolder and resolder to check and tweak.

Thanks


texts:
I am building a RPM measurement unit using 8051 micro controller. I want to measure RPM of AC motor. I have connected proximity sensor to get the pulse for each turn.

I have connected the proximity sensor output to the counter of micro controller. And I am calculating the 1 sec delay using Timer.

For each second I am calculating the RPM = pulse count[counter value] * 60.

Ex: If pulse count = 16, I am getting RPM = 960 r/m
If Pulse count = 17, RPM = 1020 r/m.

Here I am getting difference of 60 r/m.

Using the above method, I can't measure RPM of 1000 r/m. Since pulse count * 60 will not be 1000 at any given point of time.

Please advise me how I can measure RPM in precision manner.

Thanks
Umesh


texts: How to protect Li-Ion battery from a defibrillator pulse

texts: I'm working on a design where the rechargeable Li-Ion battery is placed closely (attached with a magnetic connector) to a body-worn contact. The concern is that in an event of a defibrillation, the voltage could arc to the battery contacts on the connector and cause an issue. One of the ways to ensure this doesn't happen is with an air gap of 4mm or more (for 4000V). However, since this device is intended to be small, a 4mm gap is a huge hit so I am looking for an alternative solutions. The device doesn't have to survive the pulse, just has to prevent the battery from getting damaged / exploding. I've thought about using PTC fuse to limit the current to the battery along with some ESD diodes but am not entirely happy with that solution. If you've dealt with something similar or have a better approach, I would love to hear it. Thanks!


texts: Can a power board impact watt meter readings

texts:
I've just measured two different but conflicting readings using an off the shelf watt meter. My quandary is that these measurements conflict and seem untrustworthy.

My question is: whether measuring from a power board or the wall plug matters or if there is something else at play here that I've missed?

Setup:

Reader: Arlec Electrical Meter (PC222)
Power Board: HPM 12 Socket with surge protection and indicator light
Device 1 & 2 & 3 Connected to power board. Power board connected to wall plug.

Notes: Device 2 runs under seemingly constant load/utilization for both readings.

Method:

1st Reading:
820W measured at power board plug from Device 2. ~247V. PF of 97%

2nd Reading:
220W measured at wall plug of power board with Devices 1&3 on and consuming.

3nd Reading:
630W measured at wall plug of power board with all devices consuming. ~247V. PF of 87%

Edit: These devices are electronic and 2 have computer PSU's.


texts:
I am using LPC1769 and it's port pins as below image.

DB0 to DB15: Port pins of LPC1769 used as data pins for LCD

Control Signals for LCD:

C/D :        Register Select Command or Data

/WR :        Write

/RE :        Read

LCD_OE:      Chip Select

LCD_R:       LCD Reset

Since I have used different port/data pins (ie from port 0,1,2 and 4), does it cause any problem in functionality of LCD?

Thank you in advance.


texts: Does the impedance of RLC circuit change with time ?I think that it changes because in the beginning ,the opposition of the inductor is maximum then it begins to decrease as di\dt decreases and vice versa for the capacitor.one more reason , i also think since we represent impedance by a phasor then i think it should be changing with time , isnot it ?


texts:
I am designing a board where the datasheet suggests a power up sequence. Basically, the VDD_PLL should be turned on first, after 100us, the VAA should be turned on, followed by the internal supply and then the VDD_IO. Current I am using the AMS1117 as my voltage regulator. I know I would have to chnage this to some other power up sequencing IC if i need to meet these requirements. My question is what happens if I dont meet the power up sequence? Is it merely a safet mechanism or will the board not work. Can I ignore the specfications in the datasheet?

The chip is http://www.onsemi.com/pub_link/Collateral/AR0330CM-D.PDF


texts: Why aren't magnetic substrates so used for RF printed circuits?

texts:
I've recently started working in microwave field, so I don't have  big knowledge except for basic theory.
What I've noticed is that, in rf and microwaves printed circuits (for instance for microstrip lines, patch antennas etc) the substrate material is generally a non - magnetic material (relative permeability about equal to 1).
This tendency has become so standard that most of people (and even substrates datasheets) never mention the relative permeability, since it's known to be 1.
Here and Here you may find a list of typical substrates materials, which are all characterized by non-magnetic properties, and which are choosen mainly because of their loss tangent (dissipation) and dielectric constant.
So, my question is: why not using materials with relative permeability greater than 1?
High electric permittivity materials are used when we need to:

Increase the capacitance between two metal objects;

Decrease the wavelength (for a fixed source frequence). This allows to make the structure (patch antenna, microstrip line etc) seem bigger with respect to the wavelength, and so its size may be reduced. This allows to minimize devices sizes at the cost of higher parasitic effects.

Well, even choosing a material with high magnetic permeability can reduce the wavelength and provide the advantage 2), since:

The role of magnetic permeability on reducing the wavelength is exactly the same of electric permittivity. No difference. But why magnetic materials are rarely used?


texts:
I'd like to connect my landline tellephone to my computer's soudcard, and I was about to do this when somebody warned me that the voltages are all wrong and that I will blow my soundcard.

To what voltages must I change the line, and how do I do that?

Also, the telephone line has two wires. How to I split them into input & output for my soundcards's ports?


texts: Difference of inductor rated current based on "Inductance change" vs based "Temperature rise"?

texts:
I'm looking into an inductor datasheet(page 59) and I'm having a bit of trouble understanding the difference between the ratings.

My interpretation is as follows:

1 - Rated Current based on Inductance Change is:
How much current you can put through the inductor till its inductance goes 30% off the original rating.

2 - If you "dont care" about inductance, the Rated Current based on Temperature Rise is the absolute maximum current the inductor can take before thermal failure.

Is that it? Am I missing something?


texts: Advantages and disadvantages of using igbt module with integrated rectifier bridge

texts:
What would be the main problems of using an igbt module with a rectifier bridge in an ac-ac converter project?
Noise? Temperature?
Does separating the rectifier bridge from the full bridge really alleviate the problems caused?


texts: I've got this picture under my microscope for an old Samsung Galaxy Ace mobile phone, I'd like to know what are the different pixels in the rows with a separation in the subpixels? And how are they different from the regular ones in the adjacent rows? I've tried searching for the exact circuit implementation of mobile phone touch screens but sadly didn't reach an answer.


texts:
As someone with only a basic understanding of electrical things, please bear with me.

I'm trying to convert the lighting circuit on a vintage  motorcycle from 6v AC to 12v DC (so I can use LED headlights etc.)

On this particular model, a magneto rotates around fixed coils. Originally 1 coil was designed to produce 6v and around 40 watts AC.

I have added another identical coil, wired them in parallel and connected them to a 6v to 12v DC regulator/rectifier (specifically designed for 6v to 12v DC motorcycle conversions - I'm sorry I don't have the specs for this unit).

When all wired up and the engine was running I measured around 3v from the regulator. When the RPM was increased this dropped to around 2v (I would have expected it to rise!)

Should I be wiring the coils on series? Or will this make no difference? I'm confused. There is no earth leakage. I understand that there will be some loss from the rectifier.

Also, what does it mean if something runs 'AC/DC simultaneously.'?

Perhaps not your regular type of question on here but any help or advice would be enormously appreciated!


texts: Is the value of XTAL load capacitors for ATmega328p @ 16MHz critical?

texts:
I'm going to try to assemble an MCU-based circuit using an ATmega328P-PU (Arduino UNO stripped down to essential parts as in this tutorial).

I've skimmed over a lot of posts on EE.SE about load capacitors for clock generator XTALs and they seem mostly focused about understanding their function or selecting the right capacitance value, but little is said about tolerance or other capacitor parameters, besides this answer by Russel McMahon, which points out some caveats.

Given that for this application 18÷22 pF ceramic caps are advised (see link above), are those specs sufficient (besides of course working voltage – I suppose 50V caps are more than enough), i.e. can I choose any 22pF-50V cap and that's all? Is the choice critical with respect with other cap parameters (tolerance, leakage, etc.)? In particular are multilayer ceramic caps suitable (I've seen some online shops stress the difference between single-layer and multilayer, so I wonder if it is significant for this application)?

EDIT

By critical I mean that the clock generator may not oscillate or that it will have erratic behavior or that general operation of the circuit is impeded. I'm not interested in high frequency accuracy as far as the internal circuitry works reliably (for example, "critical" would be if the UART cannot communicate with an Arduino board because the clock frequency is too different). The purpose is to burn the firmware using the Arduino IDE and libraries as they are (using an Arduino board as in-circuit programmer), without customising them and coping with different clock frequency.


texts: How Can I Get a Stable Triangle Wave With Adjustable Frequency

texts:
I am trying to make a wave generator. It will have switch modes for frequency between 1.6kHz to 1.6Hz with x10 increments. Everything is set except the triangle wave. I use a wien birdge oscillator to create a clean sine wave, then integrate it to get a square and filter it to get a triangle wave.

when switch is at position one, oscillator (using 1nF capacitors) is generating a sine wave with frequency of 1.6KHz, everything works perfect except that little plateau on the triangle wave

When I switch to second position (which switches oscillator to 10nF capacitors) I get a trimmed triangle wave

I obtain the triangle wave by filtering the square wave with a low pass filter than amplifying it with an opAmp.

Amplified sine wave passes through the R13 then gets integrated.
Integrated sine wave(square wave) passes through R14, gets filtered and becomes a triangle wave. Then gets amplified. I tried using another integrator circuit to obtain the triangle wave but it doesnt work. I believe I need some kind of auto gain, so the gain of opAmp will adjust itself after I change frequency in a way that it will not create a huge triangle wave which gets trimmed. I thought using back to back diodes like in the oscillator but couldnt make it work. I thought about removing last amplifier but then the output becomes very low.


texts: Feasibility of recovering radio transmission carrier frequency

texts:
Assuming you have an FM Radio transmission at 94.4MHz where the carrier frequency is generated by a rather accurate source (lets assume allan deviation \$10^{-12}\$), is it feasible to recover a sine wave at 94.4MHz (or even at 10MHz because thats standard for everyone) with a reasonable deviation without using an oscillator that is disciplined by it?

What would be a realistic deviation that we could achieve and what basic building blocks do we need?


texts: A question about the working principle of a frequency to voltage converter

texts:
This is a question about the big picture of a frequency to voltage converter.
For example when I use this Phoenix Contact MINI MCR-2-F-UI(-PT) f/V converter module with the settings to map a input frequency range 1Hz to 1kHz or 10Hz to 1kHz or 10Hz to 250Hz to 0-10V voltage output I observe better response at output when the input freq.  range is smaller. It means better resolution I guess.

Since I dont know the inner mechanisms of the converter Im wondering why it is like that. Is there a way to grasp the idea how this converter works and why it has a better resolution when the input freq. range range is lowered?

Finally can we say the same behaviour for an IC like LM2907?

Im wondering the general working principle so this make one understand why input range and output resolution is related.


texts:
I have a photodiode amplifier that responds to a pulse of light like this:

or like this:

depending on how I change the feedback capacitor.

Every transimpedance stability article I have read online talks about the noise gain and how the input capacitance adds a zero to the noise gain response which can make the amplifier oscillate due to a noise voltage which always present. The noise voltage never has a step response which could give me the results I am getting. It would just always be ringing.

My circuit is not oscillating! The transimpedance response is just underdamped. How do I analyze the transimpedance response? I'd like to have magnitude and phase plots of the transimpedance response so I could find the phase margin and tune the circuit to make it bigger.

Thanks!


texts:
I am running a simple picoblaze code where I am using two addresses and sending a high strobe on both the addresses, the assembly code has no loop, so technically my code should run ONLY once but the high signal on the addresses that I am using is coming continuously. I used an oscilloscope to check the output. I am posting the Glue Logic and the pico code. I am using a Spartan3 Xc3s1000-4fg456 fpga board.

Anyone here has any idea what I am doing wrong here? Here is the pico code

;**************************************************************************************
; OUT Port definition
;**************************************************************************************
CONSTANT sx1,           16
CONSTANT sx2,           20
;**************************************************************************************
; Special Register usage
;***********************************************************************************
NAMEREG SE,     TEMP1
NAMEREG SD,     TEMP2

OUTPUT  TEMP1,      sx1
OUTPUT  TEMP2,      sx2

And the vhdl code for the glue logic is

 library IEEE;
 use IEEE.STD_LOGIC_1164.ALL;
 use IEEE.NUMERIC_STD.ALL;

entity Glue_Logic is
PORT    (
        CLK         :IN         STD_LOGIC;
        RESET       :IN         STD_LOGIC;
        DATA_IN_P   :IN         STD_LOGIC_VECTOR(7 DOWNTO 0);
        PORT_ADDR   :IN         STD_LOGIC_VECTOR(7 DOWNTO 0);

        PORT_OUT1   :OUT        STD_LOGIC_VECTOR(7 DOWNTO 0);
        PORT_OUT2   :OUT        STD_LOGIC_VECTOR(7 DOWNTO 0)
        );
end Glue_Logic;

architecture Behavioral of Glue_Logic is

signal port_out1_s          :STD_LOGIC_VECTOR   (7 downto 0);
signal port_out2_s          :STD_LOGIC_VECTOR   (7 downto 0);

begin

                            PORT_OUT1   <= port_out1_s;
                            PORT_OUT2   <= port_out2_s;

process(reset, clk)

begin
    if (reset = '1') then
        port_out1_s                 <= (others => '0');
        port_out2_s                 <= (others => '0');

    elsif (clk'event and clk = '1') then

        case (port_addr) is

            when x"16"          =>

                port_out2_s             <=      x"01";

            when x"20"          =>

                port_out1_s             <=      x"01";

            when others     =>

                port_out1_s             <= (others => '0');
                port_out2_s             <= (others => '0');

            end case;
end if;
end process;
end Behavioral;


texts: Shunt resistance VS Rogowski Coil in current measurement , which one is better?

texts:
Shunt resistance VS Rogowski Coil in current measurement , which one is better ?

Just for reference I want to create small circuit that measure the power , so which one I go for ?

UPDATE 1 :
I'm measuring AC current
Isolation is required
Scale of current will be A to hundreds
It will be a permanent part of the circuit

I'm going to make an Electrometer


texts: Gyro - Determine angle accuracy from datasheet

texts:
I have a few Gyro's that I am considering for a new project that needs accurate positioning on moving parts.

What I don't fully understand is how to pick a Gyro that will report back an accurate enough angle.

Take for example and MPU-6050, how do I work out how accurate it will be at calculating angels before I go out an buy the unit.

Datasheet : https://cdn.sparkfun.com/datasheets/Components/General%20IC/PS-MPU-6000A.pdf

More Details:
The machine I'm adding the interface to is a small Heliostat. It will be static and controlled by motors. The idea is to point/move it the preferred position by hand. My main concern is will the Gyro be able to provide 0.05 degree accuracy after converting/smoothing the readings to degrees.


texts: Starting out with Arduino - beginner kits

texts:
I'm considering getting started with Arduino, and looked around for beginner kits. I've found 2 that particularly caught my attention

The Arduino Starter Kit, in the official Arduino website;
The KIT Workshop PTRobotics with Arduino Uno, in PTRobotics, found in the Arduino's Distributor's list.

Now, the second one is about 30€ cheaper, but (obviously) contains less material. So, my question is: are the extra parts in the first kit worth the extra 30€, or would it be better to save that money and later use it to buy other parts?

The way I see it, the first kit is a bit more "general", and provides a bit more freedom, but, since I've never worked with Arduino, I really can't tell if it's worth it.

I appreciate any help you might give.

I understand there is a (quite) subjective side to the question, but please try to remain objective: Are the parts worth it? Could I get them cheaper (without recurring to counterfeits)? Are they "worthless" for beginners?


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I completed an IR emitter circuit with two selectable power settings. It's working on the breadboard and I'm asking if I need the gate-source resistors for stability? As the circuit is battery powered I want to prevent wasting power.
38kHz is created by a 328P
VCCmax = 8.4V
V_38kHz=3.3V


texts: What does this transistor, parallel to the audio output load, do?

texts:
I'm reverse-engineering the analog frontend of an SPDIF-to-analog converter. I'd like to increase its output level before feeding the audio (AUX) input of a Bluetooth speaker, which seems to amplify it less than other audio inputs.

This is the schematic I obtained for left channel (right channel is identical):

simulate this circuit – Schematic created using CircuitLab

The audio signal comes from a MS4344 DAC, a chip with the same pinout as the CS4344 DAC, then goes through an SMD capacitor of an undefined value, then it seems to go directly to the RCA jack, but also to the collector of a BC848B NPN transistor, whose base is connected to 5V via a resistor.

I'm not sure what's the function of transistor. It's parallel to the load; is it meant to "take" a fixed amount of current? Maybe it can be altered to provider a higher output level?

By the way, this schematic is rather different than the suggested connection diagram (page 11 of datasheet). So I'm not sure what the designers had in mind.


texts: PIC to measure Pressure sensor "MBS 1200"

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I have a pressure sensor MBS 1200. I want to connect the same to a PIC micro controller for an application. Can you please suggest a circuit to do the same. I am not familiar with current output sensors. The datasheet is included here,

http://www.ra.danfoss.com/TechnicalInfo/Literature/Manuals/04/ICPDP21A702.pdf


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I want to drive a board with 5V and 3.3V but my input voltage is around 40VDC.
The board will draw around 750mA.
If I check the voltage on NODE1 without the 7805, I've got 28V.
With the 7805 connected, the voltage drops to 1.6V on NODE1
R2 is a 10K POT to adjust the voltage.
I used LTSpice to simulate the circuit and when the NODE1 draws:

800mA --> 28V
840mA -->

simulate this circuit – Schematic created using CircuitLab


texts: What is the purpose of the capacitors in this circuit that are in series with this VCO?

texts: I am learning about how VCO modules operate and I am rekindling an old interest in electronics in general. For one particular VCO, the manufacturer has provided a circuit diagram. Does anybody know the purpose of the capacitors in series between the tuning voltage source and the mains voltage source?


texts: Advantages of using active inductors in ICs

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I have seen that there exist many methods to realize equivalent inductors in IC through  active components. For instance, through gyrators realized with Op-Amp.

This solution will require a lot of transistors. Which is the advantages of choosing it, and not a proper inductor? I know that in ICs it is very difficult to realize inductors with L greater than 20nH because of the lack of space in the substrate, while transistors are little, with lower parasitics and their realization pattern is "standardized". But I'd say it is convenient only if it allows to get high values of L, in general L>>20nH. Which is a typical value?


texts: Kn2222A darlington pair + a relay, not functioning at low currents

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As the title explains it, I have
Kn2222A x2 transistors connected as a Darlington pair connected at the ground side of a [JQC-3F (T73) 5v] relay

The relay is connected to a 5v power supply.

the problem is, when I feed the base of the Darlington pair with low current, it won't switch the relay, it seems that the minimum current needed for the base is 0.3mA, less than that won't do a thing, looking at the data-sheet I should get at least 100*100 gain,  10000 * 0.3mA = 3A I am sure that's more than enough for the relay, unless I am missing something

I'm having hard time getting Hfe from the datasheet, and knowing the amp needed by the relay.
Transistor datasheet

relay datasheet

another question is, can the relay function at higher than 5volts? (safely)

I'm only experiencing with electronics so any more info will be appreciated


texts: STM32F407G-DISC1 not working if not connected to pc

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I have a Discovery board DISC1 version (february 2016 revision).

I had programmed a Discovery board before with no issues. The ones that I more recently bought, the DISC1 version, have a strange issue: after I flash the program, if I connect them to the PC via USB (CN1), everything works fine, but if I power it up with external +5V or with the CN1 (but not from an USB port), the LD1 led start blinking, the the LD2 red led turns on, but nothing else happens. The rest of the board is off.

I stress that this never happened with the previous revision of the same board, i always powered it up via external +5V and it always worked correctly.

Does anyone have a clue why this is happening?


texts: Impulse relay functionality without latching

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Let me start by declaring that I have absolutely no idea what I'm doing so please try to keep it simple if possible. Thanks in advance.
I have a project requirement that uses simultaneous input from two momentary switches (safety feature) to activate or deactivate  a SPDT relay. Subsequent simultaneous inputs from the same pair of momentary switches should toggle the state of the relay.
I understand (I think) that the behavior I require is referred to as an impulse or bistable latching relay. What I'm struggling with is that I also have a requirement that the relay should reset to "off" on power loss so that when power is restored, the relay remains "off" until triggered again.
I know this is the opposite of how true latching relays work, so I'm thinking that what I probably want is a non-latching relay that's implemented such that it behaves like an impulse relay only as long as it has power. But I don't know how to do that.
Do you think this can be done with some type of relay logic or off the shelf module? or do I need to build it from scratch?
Any input is appreciated. Thank you.


texts: Choosing reactance of LC tank for crystal oscillator

texts:
In the ARRL (2011) Section 9.5.4 (talking about a series mode quartz crystal oscillator) it says:

  To build a practical oscillator from this
  circuit, choose an inductor with a reactance
  of about 300 Ω at the wanted frequency and
  calculate C1 in series with C2 to resonate
  with it. Choose C1 to be 3 to 4 times larger
  than C2.

This is the schematic they provide.

1) Is there a reason for choosing 300 ohms instead of say 1k?

2) Does the choice of reactance depend upon whether you want to drive? the crystal at an overtone


texts: Back-to-back MOSFETs: common source vs comon drain?

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If connecting a pair of discrete MOSFETs back-to-back to create a bidirectional load switch, what's the practical difference between having them common-source versus common-drain?

In this particular case, I'm using a pair of p-ch FETs to isolate a battery from a load and also ensure that stored charge within the load can't return to the battery when switched off. I have a 3V6 battery so a logic level FET works fine. The PCB routing works best if I have common source, but I've seen both configurations used in literature.

In an integrated device I would imagine that there might be good reason to choose one over the other, since the common bulk silicon would most likely influence the choice. But with discrete parts there doesn't appear to be a clear reason for choosing one over the other, provided that the gate drive exceeds the body diode forward voltage drop as well as Vgth.

So are there reasons to specifically choose one of these configuration?

EDIT:

Given the base conditions: that the supply is greater than the FET Vgth plus a body diode forward drop; then either circuit works functionally. However, simulations indicate that there is some benefit to the common-source arrangement in that the switching transitions are faster so there is less power wasted in the FETs.


texts: Have I calculated the peak rectified V and diode I correctly?

texts:
A 240V (rms) 60 Hz mains supply is fed to a trans which has 20:1 ratio. The output v from the 2nd winding of the transformer is connected  to a full-wave rectifier circuit and a 10kΩ R. Assuming ideal diodes, what is the peak voltage and the peak diode I

Attempt....

240 x sq root of 2
= 339

339 x 1/20 = 17 for peak voltage

Peak voltage / resistor, will give diode current