texts: Interfacing Audio ADC CS5381 with PICMX250128B

texts:
I want a 24 bit resolution AD conversion, so I am using an audio ADC CS5385. I am not in any way working with audio signal, but I just want to get the digital values from the ADC via the I2S interface.

My ADC is the master and the PIC32 is the slave (as directed by ADC datasheet).

so after the ADC does it conversion i just want to take in the I2S signals from the SDI and send it out via the SDO. thank you for your time

// asm volatile("ei"); // Enable all interrupts - this funnction stops my refclock out

Thanks

Mclck - 8MHZ from Pbclck

I am using sysclck at 8 mhz with internal RC and pbclck divider of 1 and sending PBCLCK out as refclckout.

here is my code

define SYS_FREQ 8000000
include <xc.h>
include <sys/attribs.h>
include <plib.h>

int main(void);
void SYSTEM_RegUnlock(void);
void SYSTEM_RegLock(void);
void OSCILLATOR_Initialize(void);

int main(void) {
   SYSTEMConfig(SYS_FREQ, SYS_CFG_WAIT_STATES | SYS_CFG_PCACHE);
   DDPCONbits.JTAGEN = 0;

   ANSELA = 0x0000; // all ports digital
   ANSELB = 0x0000; // all ports digital

   TRISBbits.TRISB3 = 0; // make RA1 pin LED - 7

   // PIN INTIALIZATION
   PORTBbits.RB9 = 0; // make RB9 pin MDIV
   PORTBbits.RB7 = 0; // make RB7 pin ~HPF
   PORTBbits.RB4 = 0; // make RB4 pin I2S/~LJ
   PORTBbits.RB5 = 0; // make RB5 pin M1
   PORTAbits.RA4 = 0; // make RA4 pin M0
   PORTBbits.RB0 = 1; // make RB0 pin ~RST
   PORTBbits.RB1 = 1; // make RB1 pin M/~S

   //PORTBbits.TRISA0 = 0; // make RB2 pin output- 6
   PORTBbits.RB3 = 1; // make RA1 pin LED - 7

   // SPI PINS
   TRISBbits.TRISB14 = 1; // RPB14 = Input -25 SCK - SCLK
   TRISBbits.TRISB15 = 1; // RPB15 = Input -26 ~SS-LRCLK
   TRISBbits.TRISB8 = 1; // RPB8 = SDI - 17
   TRISBbits.TRISB2 = 0; // make RB2 pin output(SD0)- 6
   TRISBbits.TRISB13 = 0; // RPB13 = REFERENCE output - 24

   SYSTEM_RegUnlock(); // unlock PPS
   CFGCONbits.IOLOCK = 0;
   //CFGCONbits.PMDLOCK=0;

   RPB13Rbits.RPB13R = 0x0007; //RB13->INTERNAL OSCILLATOR:REFCLKO;
   SS1Rbits.SS1R = 0x0003; //RB15->SPI1:SS1;
   RPB2Rbits.RPB2R = 0x0003; //RB2->SPI1:SDO1; - 6
   SDI1Rbits.SDI1R = 0x0004; //RB8->SPI1:SDI1;

   CFGCONbits.IOLOCK = 1; // lock PPS

   //CFGCONbits.PMDLOCK = 1;

   SYSTEM_RegLock();

   //__builtin_disable_interrupts();
   //asm volatile("di"); // Disable all interrupts

   IEC1 = 0; // disable all interrupts
   SPI1CON = 0; // Stops and resets the SPI1.
   SPI1CON2 = 0; // Reset audio settings
   // REFOCON = 0x0; // Reset reference oscillator

   rdata = SPI1BUF; // clear the receive buffer
   IFS1 = 0x00;// clear any existing event
   IPC7 = 0x00;// clear the priority
   IPC7bits.SPI1IP = 3; // Set IPL = 3,
   IPC7bits.SPI1IS = 1; // Subpriority
   IEC1bits.SPI1RXIE = 1;
   IEC1bits.SPI1TXIE = 1;
   IEC1bits.SPI1EIE = 1;
   SPI1STATCLR = 0x40; // clear the overflow
   SPI1CON2 = 0x000000c1; // Left-Justified Mode, AUDEN = 1, AUDMON = 0
   SPI1CON = 0xc1028cc0; // Slave mode, SPI ON, CKP = 1

   // 24-bit audio data, 32 bits per frame

   OSCILLATOR_Initialize();

   // Enable the multi vector
   INTCONbits.MVEC = 1;

   // asm volatile("ei"); // Enable all interrupts

   while (1) {
      while (!SPI1STATbits.SPIRBF); // wait for receive complete
      PORTBbits.RB3 = 0; // light LED
      channel = SPI1BUF; // read from buffer
      while (!SPI1STATbits.SPIRBF);
   }
}

void SYSTEM_RegUnlock (void)
{
   SYSKEY = 0x12345678;
   SYSKEY = 0xAA996655;
   SYSKEY = 0x556699AA;
}

void SYSTEM_RegLock (void)
{
   SYSKEY = 0x00000000;
}

void OSCILLATOR_Initialize (void)
{
   SYSTEM_RegUnlock();
   OSCCON = 0x38000;
   SYSTEM_RegLock();
   OSCTUN = 0x0;
   // DIVSWEN disabled; RSLP disabled; ACTIVE Active; ROSEL SYSCLK;
   // OE N Driven out on REFCLKO pin; SIDL disabled; RODIV 0; ON disabled;
   REFOCON = 0x00009101;
}


texts: How do you convert a changing input (square wave) into a single high signal?

texts:
I am designing a circuit which will output a square waveform for a specific duration of time (t) but I need to be able to read the square waveform using a processor so would like to turn the changing square waveform into a single high pulse for time (t). The frequency of the waveform could be too high for the processor to read directly so I am looking for a method to convert it to a single high pulse (with duration t). I first thought about using a small capacitor which would be charged up during the rise of the square waveform and then be discharged through the low part of the waveform but I am unsure if this would work and what value the capacitor would need to be. Ideally I need way which does not use ICs (simple discrete components only would be best).
Any ideas?
Dan


texts:
I have a .mif image that I want to encrypt in Verilog. To do so, I need to read the image into the program and store it in an array.

The image would be 160 by 120 and I would like to store it in an array of size 160*120*3 (It's multiplied by 3 since each pixel requires a 3 bit number to store its color). So ideally, I would be doing something like this:

wire [16] image = read ("myimage.mif")

So far, I've taken a look at initial blocks and they seem like they might help. I wasn't able to find a specific guide for reading in images though. Note that I have to do this in Verilog, not SystemVerilog.

Could someone please show me how to do this or at the very least tell me what kind of things I should be looking into in order to be able to do this? Thank you.


texts: My project is Speed Control of a solenoid. In this project, stroke is 30 mm and I want to plunger cross 30mm in a few seconds (like 5 seconds). For this purpose I want to control the current of the solenoid coil with PWM, but it seems that the plunger does not move until the current reaches a certain amount, after which the plunger moves very fast. What is your opinion for low speed solenoid acting? What method should be used? Electrical or mechanical methods?


texts: Computer Power supply fan not spinning with proper voltage

texts:
I have a computer power supply which had 4 blown filter capacitors (3 2200uF/10V and 1 1500uF/16V).  The power supply is now working as far as powering a computer goes, however the cooling fan is not.  I jumpered the green wire to one of the black wires on the 24 pin main power connector to bring power to the components on the power supply board without having to have it connected to the pc and I replaced the fan with a known good 12V DC 0.5A fan (same as the one that came with the power supply) which did not spin either when connected.  The terminals that the fan connects to on the board are showing ~12.65v.  I was under the impression that as long as voltage was supplied to a dc fan that the fan would spin, what am I missing that is not allowing the fan to spin up?
Thanks.


texts: What is the formula for calculating out the time delay for the sum output in a ripple-carry adder circuit?

texts: I am amidst writing up calculations for electronics research, but am unsure how to calculate the time delay for the sum output. I am needing to calculate the time-delay for the sum and carry outputs of 1-bit(genus=2) and 2-bit(genus=4) ripple-carry adders. The 1-bit adder has 2 XOR gates, 2 AND gates, and 1 OR gate. The 2-bit adder 4 XOR gates, 4 AND gates, 2 OR gate.


texts:
On this AC/DC power module the terminals are labeled N and L, can I wire 220 line to line both to N and L? See link to part

https://www.mouser.com/datasheet/2/468/RAC10-K_277-1661832.pdf


texts: Position of capacitor in a full wave rectifier circuit?

texts:
Can a capacitor be connected after the load resistance in the following circuit:

Why or why not?


texts:
I have burned an arduino bootloader to an ATmega168PA. I want to use the internal 8MHz oscillator for the ATmega, and I used an arduino Uno as an ISP. For that, I did the following:

Created the directory at Documents/Arduino/hardware/breadboard/avr. In there I placed a boards.txt file, and a bootloaders folder, which contained the .hex file. Both files can be found at the end.
I found the hex file I used in this link. From it, I used the optiboot_atmega168pa_8000000L_57600.hex

The burning of the bootloader completed successfully. Also I successfully uploaded a blink example to my ATmega168PA via the arduino ISP and the Arduino IDE.

The problem is that when I try to upload something a second time, I get this error:

.

If I reburn the bootloader, I can again successfully upload a sketch. But once more, I cannot upload a second time.

optiboot_atmega168pa_8000000L_57600.hex file:

 :103E00001F92CDB7DEB7112484B714BE982F9D70D2
:103E100009F0C4D082E08093C00088E18093C100A3
:103E200086E08093C20080E18093C4008EE0A1D040
:103E3000812C912C93E0F92EEE24E39425E0D22EF0
:103E400031E1C32E8AD0813479F487D0898397D029
:103E50008981823811F482E005C0813811F486E04E
:103E600001C083E073D06FC0823411F484E103C0D9
:103E7000853419F485E08BD066C0853541F46DD06A
:103E8000882E6BD0912C982A880C991C5BC08635A3
:103E900021F484E07CD080E0E5CF843609F036C0A0
:103EA0005CD05BD0B82E59D0A82E00E011E055D0E0
:103EB000F80181938F01BE12FACF61D0F5E4AF1201
:103EC00001C0FFCFF401F7BEE89507B600FCFDCFB7
:103ED000B401A0E0B1E02C911296AD01415051091E
:103EE000FA01808130E0382BFB010901E7BEE8953B
:103EF00011246E5F7F4FBA12EECFF401D7BEE89562
:103F000007B600FCFDCFC7BEE8951DC0843769F435
:103F100024D023D0B82E21D032D08401F80185914D
:103F20008F0114D0BA94D1F70EC0853739F427D059
:103F30008EE10CD084E90AD08BE094CF813511F466
:103F400088E017D01CD080E101D07CCF9091C000D8
:103F500095FFFCCF8093C60008958091C00087FF35
:103F6000FCCF8091C00084FD01C0A8958091C6005F
:103F70000895E0E6F0E098E1908380830895EDDF16
:103F8000803219F088E0F5DFFFCF84E1DFCFCF93F7
:103F9000C82FE3DFC150E9F7CF91F1CF282E80E0A1
:083FA000E8DFE0E0FF270994CF
:023FFE000206B9
:0400000300003E00BB
:00000001FF

Boards.txt file:

atmega168pabb.name=ATmega168PA on a breadboard (8 MHz internal clock)

atmega168pabb.upload.protocol=arduino
atmega168pabb.upload.maximum_size=14336
atmega168pabb.upload.maximum_data_size=1024

atmega168pabb.upload.speed=19200
#atmega168pabb.upload.speed=115200
atmega168pabb.upload.tool=arduino:avrdude

atmega168pabb.bootloader.tool=arduino:avrdude
atmega168pabb.bootloader.low_fuses=0x62
atmega168pabb.bootloader.high_fuses=0xDF
atmega168pabb.bootloader.extended_fuses=0xF8
atmega168pabb.bootloader.file=optiboot_atmega168pa_8000000L_57600.hex
atmega168pabb.bootloader.unlock_bits=0x3F
atmega168pabb.bootloader.lock_bits=0x3F

atmega168pabb.build.mcu=atmega168p
atmega168pabb.build.f_cpu=8000000L
atmega168pabb.build.core=arduino:arduino
atmega168pabb.build.variant=arduino:standard
atmega168pabb.build.board=ATmega168PA_BreadBoard


texts:
I am "another one of those" :) with some understanding but lacking knowledge. I can identify components, know what they are for and even change them when they are visually burn or broken.
So what brings me to your wisdom is the resistor I need for this project. Its a Ryobi flashlight that burned the bulb. I like its form factor and would like to convert it to LED. I have these 3 5mm and 1 11mm laying around for some time. For what I understand the white ones are usually 3.6v and can hold up to 4v (the label on the smaller ones states even less then that), so even if I put them in series it would be 16v and the battery have 18v nominal, peak on a top charged exceeds 20v at no load.
Can someone tell me what would be the appropriate resistor to use (W & Ohms)? I have the Ryobi batts on 2, 4 and 6 Amps.
Thanks in advance!!


texts: When designing for relatively high currents, e.g. 6-10A, what is the standard practice for motor control? Is it to construct an H-bridge out of discrete components, to use integrated half bridges, or to use integrated H-bridges?


texts: How Can I Efficiently Adjust Difficulty on a Pedal Generator without Mechanical Gears?

texts:
I'm charging a battery using pedal power, like this:
pedals -> brushless generator -> rectifier -> charge controller -> battery

I'd like to be able to adjust the difficulty at the pedals electronically, so that the someone can pedal harder ("uphill") and charge the battery faster, or they can pedal more easily and charge the battery more slowly.
I can't use mechanical gears to do this, I can't modify the generator, and I only have one battery.
My first thought is to place some sort of "difficulty device" like this:
pedals -> brushless generator -> rectifier -> (difficulty device?) -> charge controller -> battery

I guess one option would be for the "difficulty device" to contain a variable resistor in parallel (between positive and negative lines). With zero resistance, the pedals should move easily because the circuit is shorted and doing nothing (except generating a little heat)... Correct? And with infinite resistance, all the electricity would go to charging the battery.
But a parallel resistor only allows me to decrease difficulty, not increase it. I could increase difficulty by adding a variable resistor in series, but that just wastes energy.
I've considered using some type of variable transformer to increase voltage, but I'm not certain if/how that would change the difficulty at the pedal, especially when the charge controller just regulates it back down to the battery voltage.
I'd really appreciate ideas on how to do this electronically and efficiently. Thanks in advance!


texts: How to add second, lower power source to car fog light?

texts:
I'm trying to make my fog lights work with the parking lights, so I have one continuous strip of light. While I'm handy enough to craft it, designing the circuit so that I retain proper factory functionality is beyond my skills. I'll try my best to explain what I need, please go easy on me if I mess up some terms.

The rear parking lights consist of one 21/5W (leftmost, also brake light) and one 5W bulb (center). The fog light uses а 21W bulb (rightmost, in the trunk partition of the taillight).
Since the fog light is driver-side only, I'll add another 21W bulb to the passenger side.
I'll run a wire from the driver-side 5W parking light, into the trunk, through the components that you kindly suggest I use, and finally to both fog light bulbs.
There needs to be a resistor somewhere along the line, and the bulbs need to be wired in paralell, due to the bulb holder design.

The result of this mess - when I switch the parking lights on, the fog lights also light up - using 5W of power each (hence the resistor), so they are exactly as bright as the other two bulbs.

Here come the tricky parts:

I have no clue how to calculate the proper resistor needed to power two 21W bulbs, wired in parallel, at 5W
Maintaining the fog light functionality - the driver side bulb should be able to draw full power from the factory wire when needed
I would like current to only go one way - no current should go from the fog light to the parking light, or from the parking light to the headlight switch module
The original fog light circuit needs to be the default - the CANBUS system checks the bulb at startup and I refuse to live with a "bulb out" warning

I would like to use simple components - relays, diodes and so on.

A million thanks!


texts:
I'm trying to understand the default voltage tolerance of the boot pin(s) used to power up into the system bootloader of an STM32F3xx.  I want to power my whole circuit at one voltage (e.g. 7V), and use this same external voltage to set logic high on the boot pin when performing a (hopefully rare) firmware update over USART1.

AN2602


texts: How do I deal with very small wire which is too narrow to fit properly into a breadboard?

texts:
I've gutted a casio keyboard to design my own version of an electronic keyboard and am using the circuit board that originally was used by the keyboard as its keyboard matrix. The issue is that the wires it used to interface between the keyboard matrix and its micro controller are very small in diameter. So small that they cannot fit into a breadboard properly. I need to have a method of soldering these small wires into a female header or some way of insulating them from each other while configuring them in a proper manner to be able to interface with headers, so that I can keep them from touching each other and also use them to communicate with a micro controller.

Could I be able to crimp each wire like demonstrated here: https://learn.sparkfun.com/tutorials/working-with-wire

Should I solder them to male jumpers and use a combination of heat-shrink tubing and 1/8 inch electrical tape for insulation?

I'd like to know of a good solution before I start buying materials, and so I would appreciate any ideas on how to go about insulating and interfacing these small wires in a way that they can communicate with the outside electronic world.


texts: Instrumentation Amplifier with Common Mode Feedback output

texts:
I'm currently attempting to design a small circuit that takes in a differential signal at < 4mv. I want to amplify this by around 1000 times.

I was reading up on Instrumentation Amplifiers, and they seem to do what I want to do, but I would also like to get the common mode signal as an output.

Are there any ICs out there that act as instrumentation amplifiers, but also have a pin outputting the common mode signal?


texts: Anyone have any idea what type of receiver/transmitter that is

texts:
I got those from someone and it does not come with any kind of datasheets
I’m guessing they are receiver and transmitter as they both have kind of an antenna.. anyone have an idea of the model so I could google the datasheets
Thanks!


texts: Proximity sensor for height from snow covered ground

texts:
I will preface this by saying that I am a hobbyist not an engineer, which is probably why I even have to ask this question.

Like the title says I want to know what type of sensor I can use to get the height of an object from the snowpack covering the ground, not the ground itself.

It will be attached to an object in motion.

Some sensors I have looked up state that they go through snow in their descriptions, but I am unsure if they simply mean falling snow in the air or if the meant packed snow on the ground.

So far the options seem to be laser, radar, infrared, ultrasonic, and possibly optical.

An accuracy of inches would be preferable but feet would be ok.  This rules out barometric pressure.

Any help would be greatly appreciated.


texts:
I need some explanations about the MOSFET parasitic capacitances. Precisely, what I studied is that there are those parasitic capacitances:

But generally in digital electronics texts I see that they are not considered (for instance let's consider a CMOS inverter): there are simply an input capacitance (between input terminal and GND) and an output capacitance (between output terminal and GND).

What is the physical cause of them (for instance we know that CGD is determined by the overlap between the gate and drain metal's etc)? Are they equivalent models of the previous capacitances (and if yes, how do we obtain them)?


texts: What's a good way to start learning how electronics and circuits work?

texts:
I literally already tried getting a degree in Electrical Engineering, and I hated it, and I switched to Computer Science.
But here's the thing-- I find circuits and electronics and electrical devices FASCINATING! I just don't understand them.
My degree program (which was at Rensselaer Polytechnic Institute, no slouch of a school in engineering) was so busy teaching me how to apply differential equations to circuit diagrams that I never actually learned how the components of a simple house fan actually WORK or what they do.
Meanwhile there are all these kids in the program that come to the school already building robots, having taught themselves somehow-- and they're not using differential equations or Fourier analysis. They just understand, and they build. That's what I want to do.
How do you learn to understand these things? Is there some particularly good site, or book?


texts: what is the reason behind DC level shift of the optoisolator ouput(collector of photo transistor) terminal?

texts: i am using SFH-610A optoisolator to switch 1KHZ PWM signal. on input side of opto i am triggering from micro controller with series resistor 500 ohms. and on the output side i have pull-up of 3.3V which is connected to collector with 1Kohm resistor. then the collector terminal is connected to another micro pin through 1k resistor. i am seeing DC level shift of 2V on the collector terminal.can anyone explain the reason behind that ??


texts: 74HCT244 UART level translator, how would the circuit look?

texts:
I am building a UART 3.3V to 5V Level translator between a Raspberry Pi and a ATMega328.

The 74HCT244 is my choice of translator but I can't find a good example of of hooking it up.

Am I right that I should power it with 3.3V(VCC)?
Output enabled(Grounded)
3.3v TX on Input 1.This should Output 1 at 3.3V to the ATMega328 that can work with 3.3V logic.
5v RX on Input 2 with Output Enabled. Connecting Output 2 at 3.3V to the RPI.

Number 4 to me is the bit I am not certain about. If I run the VCC at 3.3V will the input pins accept voltages above VCC.


texts:
A seller sent me by mistake a bunch of LM2941CT. I checked the specifications and I see they are interesting, especially given I'm running out of LM317.

I would like directions for choosing one over the other for small hobby projects, especially for those where I need adjustable and clean output (low power lab power supply).

What I already noticed:

in LM317 it is suggested to change the resistor ADJ-GND to change the output voltage, in LM2941 it's suggested to change the resistor Vout-ADJ. It makes the use of linear pots straightforward.
in LM2941 the minimum output is 5V, in LM317 it's 1.25V. Most of the time is ok, and when I want to go lower I guess it's possible to connect GND to a negative -5V rail (the same as getting 0-1.25V with the LM317).
LM2941 requires a specific capacitor value and ESR
LM2941 has way better ripple rejection than LM317 especially in 10-1000 kHz.

Anything else?


texts:
I am building a system with multiple PCB cards.

The whole system has a Chassis Ground; connected to a main Power Supply reference.
All cards will be powered in reference to Chassis Ground.
Each card has its own Isolated supplies ie DCDC for Digital Signals & DCDC for Analog Signals
Data will be transferred along IO lanes in reference to Digital Ground

Basically this diagram:

Now the problem I have is how to reference the Digital IOs of each card to the Mother board's digital ground? If I were to just connected the reference of each cards digital supply I assume I would have substantial amounts of current flowing between the cards and the digital reference would be constantly moving around.

Or have both the digital reference and supply provided by the mother board, but I want this design to be expandable and not have to worry about increased current demands if I add more cards.

Ideally I want the cards to be completely isolated. Some of the things I thought of were:

using back2back schottky diodes to reference each boards digital ground to the mother boards. Though this could cause IO levels to be out of spec and damage the electronics.
using an OPAMP to create a ground reference on each card. I thought maybe the opamp would then start sinking all the circuits current rather than DGND, but if the OPAMP is on different supplies I think thats impossible.


texts: Derivation of ripple voltage formula for simple half-wave rectifier

texts: Im solving a problem where I have to calculate the ripple voltage for a half-wave rectifier (with a diode and capacitor) and the formula is V=I/(fC). I like to know where the formulas come from, how can I arrive at this result ?


texts: Finding current using Kirchoff Law, but getting unsolvable system

texts:
Hello, the original circuit above is where I am trying to find I1, and I simplify it the figure below and assuming the following current directions.

Using Kirchoff current and voltage laws I end up with

However, plugging in the equations into my calculator it says there is no solution. Is it with my kirchoff current equations (first 4 equations) because if I add up all current law equations I end up with 0 = 0. Can anyone tell me what I am doing wrong? Thanks for any help.

EDIT:

As other mentioned I need more KVL equations. But I also need my KVL to be independent loops, so I need at least 3 independent KVL equations.


texts: Why is PWM used to control LEDs even when they're only used On or Off?

texts:
I've noticed on cars with LED tail lights that they have a flicker to them - I presume because they're PWM controlled.
But I've seen it on vehicles where brake lights and tail lights are separate luminaires, therefore are just on or off and do not have varying brightness. I understand that LEDs need to have current through them limited, but I don't see how PWM would achieve this?

Edit: bad phrasing - sorry. Better phrasing: why would the LEDs be flickering even though there is no apparent feature to allow changing of the brightness? Perhaps the brightness is factory set, or maybe there is a feedback circuit to keep brightness constant. But could there be any other reason?

Thoughts: because a vehicle's battery has a significantly different voltage across it when the engine is off or on, (12v vs 14.5v) perhaps there is a controlling PWM circuit that keeps brightness constant over a range of voltages. Saying that, I'm convinced that smart phone screen back-lights have some flicker to them even on full brightness, yet their Li-ion batteries' voltages are near constant.


texts:
I have a 24VAC/60Hz solenoid. I used 12VDC just to try, and it worked good (well needless to say it worked as expected with 24VAC/60Hz).

What are the effects of a solenoid that's designed for AC running with DC? Applied force does not seem to be a problem in this case, so I think the main issue would be heat, as it is not running on the power source it was designed/optimized for. Technically speaking, what types of losses should be expected?


texts: Diode built-in voltage and barrier voltage (forward bias voltage) are they almost equal? how do they relate to each other?

texts: I am little confused between the built in potential that is built up in the diode depletion region and the barrier voltage that needs to be applied across the PN junction to start conducting. My thoughts say that barrier potential must overcome the built in potential for the diode to start conducting through depletion region but I am not sure if am all correct. If that is the case, does barrier voltage equal or little greater than the built in voltage of diode?


texts: What is the functional relation between PWM duty cycle for LED and its luminous intensity (candelas)? Linear or not?


texts: Which Value of R1 do I use for thermistor-controlled fan?

texts:
(source: electronicdesign.com)
The MOSFET I am using is IRLU014PBF-ND. I am using a 10k thermistor, and a 24VDC fan, instead of 12vdc.


texts: How does this circuit with a MOSFET and LED work if the respective diodes are facing opposite directions?

texts: This could be a stupid question, but I don't get how this circuit functions properly, considering that the LED is facing the opposite direction as the body diode within the MOSFET. Is this generally how MOSFETs are supposed to be arranged when driving an LED or something like this?


texts: How can the Vss or Vdd pins of a MCU handle sink or source current?

texts:
Today I was seeing the datasheet of STM32F103 MCUs and I came across with an interesting thing. assume I have an STM32F103RET6. it's a 64pin MCU of STM32 series. the pinout is this:

It has 4 Vss and or Vdd and 51 GPIO pins (the rest of pins are ain't important for my question). look at Absolute maximum ratings

The total current that all Vss or Vdd can source or sink is 4*150=600mA. as I said we have 51 GPIO pins. if we would use them as source or sink for current then they would draw 51*(+-25)= (+-1275). the point is that the total current that all Vss or Vdd can handle is less than 600mA while the total current for GPIOs is 1275mA. Why?

also that's not only belong to STM32 family. I have checked out AVR family. for example ATmega8a. DIP package:

It has one Vcc and one GND while there are 22 GPIOs. each Vcc or GND (ATmega8a for DIP package just has one Vcc and GND) just can handle 300mA while there are 22 GPIO and the total current is 22*40=880mA. also for MLF or TQFP packages, it's better than DIP because they have a couple GND and Vcc.


texts: Skin depth reference data for common materials

texts: Is there any well-regarded publication that gives values for skin depths of common metals (Al alloys, brasses, other engineering alloys) in the Hz-to-MHz frequency range?  I am not an electrical engineer, perhaps there is someone here who knows such a source of reference data.


texts: What is the voltage from which a normal humans starts feeling electric shock?

texts:
I want to ask what is maximum voltage or amperage or both which a normal human can not feel.
There is no feel of shock when we touch any terminal of a 12 V Battery what is the reason behind it?


texts:
I'm trying to design automotive-oriented circuit to limit ignition pulse duration from OEM ECU to an aftermarket ECU plug-in device. The device expects +12v pulses no longer than 9ms, while the car in question produces ignition pulses in 10...20ms range.  The pulses can always be 9ms, so there is no need for them to be proportional to the input. I'm in a kind of brain-freeze situation trying to choose between an edge-triggered monostable multivibrator circuit based on 555 timer and some MCU contraption like opto-decoupled AVR + BJTs as 12v outputs. I understand that MCU will most likely produce more accurate and less temperature-dependant timings whereas analog circuit can be a bit fiddly to fine-tune the output.
Right now I'm more into MCU approach but it feels kinda cumbersome to make all these input-output circuitry.
Is there any  go-to approach to the task like this? Can I user something simpler like an RC differentiator circuit?


texts:
I am trying to learn Sum-of-Products and minterms and maxterms for logic design, but I don't know how the book gets the f(x1,x2,x3) part.

I think I understand the minterm from the first pic (it's like you do the inversion if any of the bit is 0?), but the part I dont get is the second picture where from x1,x2,and x3, they get the  f(x1,x2,x3).

How did they get from the row numbers to f(x1,x2,x3)?


texts: Why does my Inrush Current Limitation not work sufficiently?

texts:
I have a battery powered application and want to somehow "protect" the battery from seeing too high currents. For that I have introduced a serial resistor to limit inrush current. After a certain time the resistor gets bypassed via a Mosfet.

It has an effect on the inrush current but it's still not like I would imagine it.

When meassuring with a current probe between the Battery and my circuit I can still see a peak when switching power on as well as when I activate the Mosfet (blue line). (red line shows voltage on uC pin)

can someone explain what happens here and how to prevent those spikes?

//e: uC is a STM32 and configured as openDrain without internal PullUp/Down

//e2: after adding a N-FET to activate the P-FET as suggested it looks like this:

//e3: so the first spike is still there, even when disconnecting the uC by removing R50 as suggested by @DKNguyen

//e4: implemented @Indraneel's Solution with C2=0.1uF and R2=500k and keeping R3 at the initial 18ohm. This could be a solution. Still curious why it is not working with the uC


texts: How to rewrite ULCO error compare between genvar and int?

texts:
Trying to propagate a valid signal to one of several destinations I write the following code. The problem is there is a ULCO error (Unequal length in comparison operator) between the genvar unit and the register current_unit_r. What is the recommended way to describe this logic?
input wire valid;
wire [NUM_UNITS-1:0] valid_per_unit;

genvar unit;
generate
   for (unit = 0; unit < NUM_UNITS; unit++) begin : gen_valid_per_unit
      assign valid_per_unit[unit] = valid && (unit == current_unit_r);
   end
endgenerate


texts:
I am trying to determine what two parts of the Arduino schematic are (I am quite new to reading schematics). I have circled the areas of confusion. Please let me know what these components do and whether they are necessary in the design as a whole.

Thank you so much for the help in advance!


texts:
Assuming we have this circuit:

simulate this circuit – Schematic created using CircuitLab
Assuming D1 is a silicon diode and D3 is a germanium diode,Will D1 be turned on so the VAB  = Vfd1 or not?
I know that if we didnt have the resistor D1 would not turn on but now i am unsure.I also know that if we had a resistor ,with a smaller resistance than R1, in series with D1 both would turn on.
[]
I assumed that D1 conducts and found the current 0.003A.But I assumed D1 conducts it may not what should I do from here?


texts: How to measure the current delivered to the load by a high voltage (>50 V) non-inverting op amp amplifier?

texts:
I would like to measure the current delivered to an arbitrary load by a non-inverting op amp amplifier. Key information for this amplifier and design goals:

The output voltage swing is high (up to about 100 V). The frequency range of the amplifier is DC to 1 MHz or so.
Output current to be measured is in the range of \$\pm 100\text{ mA}\$ (i.e. relatively low current, and bidirectional). I'd like this measurement to be accurate down to about the \$10 \mu\text{A}\$ range.
I don't have access to the low side of the load, so I can't just add a low side sense resistor to the load and measure that current.
The output of the current measurement circuit should be a voltage and it may be low bandwidth (DC to a bandwidth preferably in the 100 kHz range, as is typical for many current shunt monitor ICs, but the bandwidth may be lower if necessary). It does not need to have the bandwidth of the amplifier itself.
Board space and cost are not a significant limitation. I don't want to have to buy a dozen ICs and spend $100+ for the current measurement circuitry, but I'm willing to spend extra for performance. For example, I'm willing to implement two unidirectional current measurement circuits (one for positive and one for negative current) instead of one bidirectional circuit if necessary.

I've looked through Linear Tech's excellent and quite comprehensive Current Sense Circuit Collection but I didn't see a solution for my problem, which is complicated by the fact that the measurement is neither "high side" nor "low side" (since the voltage at the load varies according to the op amp output).

Ignoring the high output voltage swing requirement, it seems to me that the best way to measure the output current would be to add a sense resistor to the amplifier output and measure it with an instrumentation amplifier. There are two possible locations for the sense resistor, shown as \$R_{\text{sa}}\$ and \$R_{\text{sb}}\$ below1:

simulate this circuit – Schematic created using CircuitLab

\$R_1\$ and \$R_2\$ are given example values to indicate the order of magnitude of their resistances. They need to be high-valued otherwise the current through them will be significant when the output is a high voltage.

The problem with this solution is that I haven't found any instrumentation amplifier ICs capable of a supply voltage as great as the 100 V output swing. I could build an in amp out of op amps that are capable of such a high supply voltage (e.g. the LT6090), but I'd lose out on the excellent resistor matching that gives an integrated in amp good CMRR (definitely important for this solution).

Is there a better solution for measuring the current delivered to the load by a high voltage non-inverting op amp amplifier? Or is there anything I can do to improve the performance in this application of an in amp built out of high voltage op amp ICs?

1\$R_{\text{sb}}\$ is the easier solution since the current through it is exactly the same as \$I_{\text{load}}\$. However, in that case the op amp's feedback is not taken from the load itself -- there's a small output voltage error equal to the voltage across \$R_{\text{sb}}\$.

\$R_{\text{sa}}\$ avoids this error but the current through it is \$I_{\text{load}} + I_{\text{f}}\$. Depending on the values of \$R_1\$ and \$R_2\$, \$I_{\text{f}}\$ may need to be subtracted out of the current sensed through \$R_{\text{sa}}\$. This shouldn't be too difficult, as \$I_{\text{f}} \approx V_{\text{in}}/R_{1}\$.


texts: How to package pressure, temperature and humidity data for UPD/TCP?

texts:
I'm using a Microchip RN1810 wifi module to learn about how to send data (from a PIC24F32KA302) using ethernet /wifi to another device like my windows 10 PC. I'm reading the pressure, temperature and humidity from a BME280. I got that part working. Now I have to figure out the client/server thing and the actual sending of the data. I want to connect the RN1810 to my router. I realized that I can connect the RN1810 using UDP or TCP but that's just a connection, right?. Then, I need to send the actual data which seems to be up to me how/what to send? Is there a "standard" way of packaging/sending this kind of data that I'm not aware of?
BTW This is the first time I'm doing this wifi stuff so feel free to point out anything that seems wrong. I'm aware of the "not for new designs" status on the RN1810 though.


texts: reducing mechanical vibration from a PSU

texts:
I have a keyboard synthesizer which emits a 60Hz hum due to mechanical vibration of its PSU. The vibration is magnified by the metal chassis of the synth which acts as a soundboard. It’s very annoying in a quiet home studio. The manufacturer does not consider this a problem and is unwilling to help.

What can I do to dampen this vibration? I was thinking of installing some rubber washers between the PSU and the posts it sits on, but I was concerned about blocking paths to ground (labeled M1, M2, M3, M4 in the picture below).


texts: MSP430 Energia Basics ReadAnalogVoltage output 11 Volt

texts: I'm a beginner starting with the MSP430F5529 Launchpad. I'm just running the Basics code 'ReadAnalogVoltage' that comes in Energia to test the voltage value. I literally have all the wires and potentiometer hooked up the same way as the tutorial says (please refer to the photo), and I didn't change any code at all to the default code that comes in Energia. However, as you can see in my screenshot, my serial monitor is printing out a voltage value of 11 - 12, when I think it should be just about 3, or at most 5. Could someone please please help me figure out why this might be happening?


texts: If amplitude (say voltage) of a 60Hz sine wave increases, doesn't rise time increase?

texts:
How does rise time relate to frequency? If I take 0-pi/4 of 2 60Hz sine waves, one being 2V and one being 10V, would the 10V have a higher frequency component because it has a steeper slope?

I hope his isn't one of those questions where you think about it and then delete it as quickly as you can.


texts:
Optimization kills the switch statement that I need to use in a function
Hi all, how are you?. I'm doing a project with a STM32F103C6 (it has 32KB flash) and I had to activate optimization options to not run out of memory, right now the optimization options is -Og. After activate optimization a function that I have to know the position of a substring and after that I'm trying to use a switch statement that the compiler is killing and obviously I can't but I don't know why.
Here are de function definitions:
void Selec_Opera(char *ent, uint8_t dim)
{
volatile uint8_t pos = 0;
volatile uint8_t lugar = 0;
//  uint8_t com[T_COMANDO] = {0};
pos = strindex(comandos, (char *) eComando);
for(lugar = 0; T_COMANDO*lugar <= pos; lugar++)
{
    asm("nop");
}
switch(lugar)
{
case 0x01:
{
     lugar++;
}
break;
case 0x02:
{
     lugar++;
}
break;
case 0x03:
{
     lugar++;
}
break;
case 0x04:
{
     lugar++;
}
break;
case 0x05:
{
     lugar++;
}
break;
case 0x06:
{
     lugar++;
}
break;
case 7:
{
     lugar++;
}
break;
default:
{
     lugar = 25;
}
break;
}
}

volatile uint8_t strindex(char s[], char t[])
{
uint8_t i, j, k;
for (i = 0; s[i] != '\0'; i++)
{
    for (j=i, k=0; t[k]!='\0' && s[j]==t[k]; j++, k++);
    if (k > 0 && t[k] == '\0')
    return i;
}
return -1;
}

and I'm calling Selec_Opera() from main like follows:
while (1)
{
  if(HAL_I2C_Slave_Receive(&hi2c1, eComando, T_COMANDO, HAL_MAX_DELAY) != HAL_OK)
  {
      codigoError = 20;
      Error_Handler();
  }
  else
  {
      Selec_Opera((char *) eComando, T_COMANDO);
  }
/* USER CODE END WHILE */

/* USER CODE BEGIN 3 */
}

The I2C function is working well, the problem is with the function Selec_Opera(). If you wanna know T_COMANDO is defined as 4 and eComando is the array where I'm storing the received stream.
When the Selec_Opera() function is being executed it can be seen that almost all the switch options are not compiled, some pictures can show correctly what I'm tring to explain.
The following image shows that when I'm doing a debug session the debug file has the text but almost all the "switch" options code hasn't been included in the executable file (I need this)

only option 7 and default are included, I've tried only for test with reduced options and the behavior is the same, only the last numbered option and the default option are included in the code (this can be seen because at left is written the memory position of the instruction)
I've tested the "for" statement and it is working well selecting the position where the string is so I don't know what is happening with the switch.
Can anyone help with this?. Thanks in advance for the help.


texts:
In the picture above I am trying to implement a steerable antenna, by means of the phase shifter chips U1, U2, and U3. Each is capable of varying the phase of the input by a maximum of 100 degrees (output depends on the bias). My goal for the antenna is merely to achieve the steering effect by changing the phases. Given that each phase sifter has a insertion loss of 1.4 dB, will I be able to see any steering effect?
My thinking was that since 1.4 dB power loss means a loss of about 14% power, and since without the phase sifters, the array would essentially be a parallel connexion of antenna elements (ANT1, ANT2, ANT3 and ANT4), with the sifters I would still be able to split power among the antenna elements.

So if my input power is 1 W, would
the first antenna receive 0.25*1= 0.25 W,
the second antenna receive 0.25*0.86 = 0.22 W,
the third antenna receive 0.215*0.86 = 0.18 W,
the fourth antenna receive 0.18*0.86 = 0.16 W ?

The antennas are monopole antennas designed to work at 2 GHz. I will be testing the steering effect by using a Light Emitting Diode connected to a receiving antenna.


texts: How does logisim differ from redstone and real life circuitry?

texts:
I recently developed an interest building circuitry systems. It started in Minecraft and then grew when I picked up a micro controller from Radio shack to build an RC car with.

Obviously I'm most familiar with Minecraft mechanics. So in an effort to educate myself I downloaded Logisim. The learning curve has proven steep. The thing I'm stumped on currently is how I can go about wiring my own logic gates, rather than relying on the ones available. So I started with the simplest, the OR gate.

In Minecraft you set two buttons a few blocks apart from each other and connected to a single line of redstone running to a lamp. Bam... OR gate.

In Logisim they have a special icon with 5 input nodes and 1 output node. As many buttons as there are INs may be attached as INs, and any combination of them may be pressed simultaneously to produce a signal.

GREAT! But try the Minecraft method in Logisim and the wire turns red and produces an E, presumably for Error, in the LED.

So my questions are:

Why do two IN devices on one line produce an error in Logisim?

What does the error represent in real life?

(priority question) How can I go about building my OWN logic gates from fundamental pieces like wires, nodes, capacitors, resisters and etc?


texts: What happens when a resistor is in-between two parallel resistors?

texts:
I wanted to know what the rules are, if a resistor connects to parallel resistors(The R3 resistor), how the current flows, and what determines that.
The question was find the total resistance of the network, and the current going through each resistor. We solved this in my class setting up system of equations, like the current going through R2 plus current going through R1 should be  equal to initial current, and Kirchhoff's Voltage Law(Voltage loops). The answer we got is 10A(total current), but the teacher did not know the solution off hand. He also assumed that current would flow left to right, because the left resistor in the initial parallel had less resistance so more current. He said this would control the flow through the wire, but I thought voltage would control which way the current flows. And since they are parallel, the voltage would be the same, so no current would flow in the R3 resistor.  Any explanation to the problem would be appreciated, specifically what are the rules about current through the R3 resistor?


texts: Double BJT circuit with one BJT off and one in saturation

texts:
In the circuit below, due to the base voltage, the circuit becomes a common-emitter setup. However, assuming a reasonable value for the base current the BJT should be in saturation.

However the value given for β is a βmin value (βmin = 30), which only holds for active forward mode. I attempted to calculate the βforced value by assuming an Isc/Is value of 100, which yielded βforced = 14.45. However using this value with KVL from B to E gives 10 - 10000ib - 0.7 - 1000(βforced + 1)ib = 0 yields an ib value of 0.365 mA and an ic value of 5.3 mA, which is different from the value of ic given in the book (4.35 mA).

What am I doing wrong here? It seems like it should be a straightforward question but I must be doing something wrong.


texts:
Studying thermocouples (T/C), I have a question regarding the output.
Generally speaking, in the case of T/C, we measure the thermoelectric voltage in millivolts.

Why do we calculate not current, but voltage?
I think T/C has current output too.

When I measure current via multimeter, I have seen the current is changed.

My guess is...Current is generated, but not proportional to temperature.
Current does not have linearity.

Is it correct?


texts: Connecting a Solar Panel and Power Supply in parallel, in order to power up a load

texts:
I am using a Solar Module to charge a LiPo battery. The current supplied by the solar module goes into a battery charger IC and from there to the battery.
This works fine.
Now I want to add an external usb charger which will also charge the battery.

The first problem I have is: What would happen to my solar module if the voltage from another power supply will be connected to its terminals ?

The second part of the problem: I need a selector circuit that will disconnect the solar module's output while the usb charger is connected and will reconnect it when the usb charger has been removed.

Later Edit

Addressing the OR'ing diodes suggestion:
Here's why I don't want to use a diode on the Solar module's output:
The battery used on this project is a Li-Ion 2800mA Type. There's a microcontroller on board which sleeps most of the time. Once in a while (for a few minutes every 2-3 days) it wakes up and drives a motor (an Hbridge is used). The power consumption is not very big but ... the solar module delivers a top 100mA /6V. This is a slow rate of charge. If I place a schottky to isolate the solar module from a second power supply I will miss those .1 - .2 volt (forward voltage) dropping on the diode.
Now let's assume the sun doesn't shine very bright for a few days or a week, and the battery discharges to around 3.5v. That's the lower limit for the LDO which provides 3.3V for most of the logic onboard (including the motor driver, the microcontroller and the motor itself). That's the reason I wanted to add the second recharging method.
So basically I'll use a 5V usb charger to recharge when necessary.
I thought about using a DPDT switch (half will switch power on/off and the other half will comute between the two input supplies for the battery charger). But I have some issues with the dimensions and honestly I'd preffer the electronic switch in this case.

Addressing the electronic switching:
I saw an app note from maxim. The MAX6326 seems a good choice for this scenario. But a bit expensive. I would preffer a simple approach (as in: as few components as possible) using mosfets. And I need help with this approach and choosing the right mosfets.
Or perhaps someone has another suggestion to solve this in a more elegant way.

Thanks a lot


texts:
We're trying to output a full mono-colored screen signal in 640x480 resolution over DVI to a Samsung monitor from an FPGA board. The problem we have is that we don't get any picture showing, instead the monitor show a small grey box with the text "Not optimum mode mode\nRecommended mode\n1920x1200". From this point we find it very difficult to troubleshoot.

Perhaps the sync signals is a bit of? Or the amount of pixel data sent is wrong?

What are the requirements on the H-sync and V-sync? Do they need to be active for a long period of time? Is this time very exact or will the picture show if the syncs a few clock cycles too long or too short?

Should H-sync be active during the V-sync? No we have two H-syncs during the duration of the V-sync. Does it sound ok?

What happens if we just send 639 pixels per line or as many as 641? Will the picture show?


texts:
I'm pretty new to hardware stuff.
I have a basic idea to build a hardware controller for some proprietary software. I would need to read about 60 analog faders/potentiometers and 30 buttons. Also I need to drive about 40 LEds.
I have Arduino or Raspberry Pi at hand. Up to 60ms delay from mechanical movement to registered value would be ok.
I found some digital potentiometer accessible via I2C but at a hefty price (14$ per piece - I'd need about 60 of them)


texts: In general, how do I know if my project needs a file system?

texts:
This question gives a good high-level overview of when an operating system is appropriate on an embedded platform. The three topics mentioned are networking requirements, GUI requirements, and file system requirements.

Networking and GUIs are obvious enough, but I am wondering when a file system is appropriate and/or required for an embedded system. What sort of embedded tasks lend themselves to a file system solution?

Maybe something like a data collection application, where previous measurements or log files need to be stored for future reference?


texts: Unvalid output voltage of LM35 temperature sensor

texts: I have connected once the Vss and Ground of my LM35 sensor reversely wrong. After correction of this, the output voltage is 0.5 V which seems to be invalid in room temperature. I'm not sure if the sensor has been destroyed because of incorrect connections. It is also important to know that I am implementing this sensor for the first time and I have never used it before. I would appreciate your ideas about this issue.


texts: Distributing the output capacitance of a buck regulator

texts:
Buck regulators often specify the value and placement of the output capacitor.
Typically 10µF placed very close to the buck regulator.

However, what would the effect be of replacing the 10µF output capacitor with 10x 1µF capacitors. Where only one of those are placed immediately at the buck regulator, and the other 9 are decoupling capacitors at the load. Within an inch or so from the buck regulator.

The 1µF capacitor close by the buck regulator should handle the high frequency components of the buck switching just as well or better than a 10µF would, and the total capacitance is 10µF so the regulator loop should function properly.

For point-of-load buck regulators, this distributed output capacitor approach would have quite some practical advantages nowdays when 1µF is readily available in 0402 footprint.

Is there a downside which I am not seeing?

Clarification 1:
The current at the output of a buck regulator is DC plus a small triangle wave at the switching frequency (typically 1-2MHz). Triangle waves do not have any significant HF content.
Examples can be found here:
http://electronicsbeliever.com/sizing-the-inductor-of-buck-converter-and-setting-its-operation/

Clarification 2:
Physically smaller capacitors have lower ESL (which is better). See for example:
SMD capacitor package size and high frequency performance


texts: What does this symbol on the box of power supply mean?

texts:
I always see this symbole behind electronic devices.

A close-up image of the symbol:

What does it mean?


texts:
I'm looking at designing my own Bluetooth Receiver essentially. Playing music from my phone to a Bluetooth receiver, to output via AUX.

I was looking at the Nordic range of MCU's for this application however I'm a bit undated with information and need a push in the right direction.

Does anyone have any recommendations on a Bluetooth MCU that would just simply receive the music and then output it.

I'm aware it's against the rules to specifically link products but was hoping someone could possibly tell me the term's of features I'd be looking for in an MCU e.g. (Bluetooth 5, DSP(?))

I appreciate any help, just hoping someone with more experience and insight than me can give me a direction to look into.


texts: How can I see the magnitude and frequency of a signal (DFT) in PLECS?

texts:
I am trying to obtain the Fourier transform of a signal by using the DFT of PLECS but I got some weird results.
Here is a very simple sinewave generator and the DFT block:
DFT_plecs_1

Here are the results on the scope:
DFT_plecs_2


texts: Electric potential Vss (negative) in Diodes, Mosfets and BJTs

texts:
I am studying electronics and I am in confusion with the way the book uses the Vss (negative) electric potential.
In particular, let's say, I can imagine Vcc or Vdd as the electric potential obtained by a voltage generator whose positive electric potential is 5 V and the negative potential 0 V.
If we talk about Vss (negative electric potential), how can I immagine the voltage generator which generates this negative electric potential? I hope someone can help me.


texts:
I'm trying to get a hold on bootstraps for high side n-mosfets. as i currently understand it, it works somewhat like this:

when pwm is high, mosfet is closed and capacitor is loaded to 12V.
when PWM goes low -> gate gets 12V -> mosfet is kind of on -> witch brings source up to 12V -> negative of the capacitor gets pulled to 12V -> positive of cap goes to 24V -> gate gets 24V -> mosfet is fully on.

if i now wanted to switch higher voltages (say 300V) the mosfet would break because i would have 300V between gate and source, witch is waay above the usual  max Vgs.

from the top answer from this post it appears to me that a configuration like this works:

but i don't really understand how, since there would only be 5V on the gate, when way more are needed to open up the mosfet.

so my questions are: is my understanding of bootstraps and mosfets not correct and the 2nd circuit works? how does it work / how could it be changed to work?


texts: What are the big plugs for that you find on high demand devices in North America (120V-Areas)?

texts:
Talking about AMEA socket system and 120V.

High power demand devices like A/Cs do have bigger plugs with some switches on them.

What exactly is their purpose?

Seems like a fuse but isn't the socket cirquit fused against overload?


texts: How does CAT6 cable extend the range of an HDMI cable

texts:
Why is an un-powered CAT6 cable able to extend the length a video signal can be transmitted compared to a HDMI cable?

Is the limitation on high speed data transmission cables such as HDMI mainly due to attenuation of high frequencies rather than the impedance of the cable?


texts: Single battery for different voltage components

texts:
So I have a 12V DC motor and a 6V stepper motor. Ideally, I would like both of them to draw from the same 12V battery pack (due to build constraints). The DC motor will be fine but the extra 6V running through the stepper could damage it, right?

Is there a way I could have one power supply (12V battery pack) and have both motors drawing from it? So DC motor drawing 12V and stepper motor drawing only 6V. I've read about voltage dividers, but would that mean wasting 6V in the circuit through resistance?

Can I use a buck converter in series between the DC and stepper motors to step down to 6V?
Or can I simply connect them in parallel so that 4 batteries to go the stepper motor then 8 batteries go to the DC motor, then they both connect to ground?


texts:
Let's say I need a 20mm wide trace in 1oz copper to handle some high current.
Could I just have a 10mm trace on one side and another on the other side, connected by a plated hole to handle the same amount of current?

Sadly, due to costs, I would like to avoid going with thicker copper on the board.


texts: Physical Implementation of RSA on Embedded Systems

texts: RSA can be used to prevent unwanted software modifications on an embedded system. How can this encryption algorithm be implemented physically? I mean, which peripheral/main units can be used to check the digital signature and how do they do this?


texts:
I was looking at a this CUI power jack connector and I noticed that it has a switch which is NC, and I think goes open when a connector is plugged in (pin 2/3).

There's no clear distinction I can make out between which pin (pin 2 or 3) which is actually electrically hooked up to the outer housing (in my case ground since my adapter is center positive).

Which pin should I connect my ground to? If I don't need to detect if the jack is plugged in, can I just short out the two pins and not worry about the issue?


texts: Record signal when two items touch each other

texts:
I have a Carrera GO!!! race track. There's a plastic mechanical lap counter that adjusts every time a car passes it.

What I would like to do is to have some sort of electrical connection that when the car passes through the lap counter, the counter creates a connection between two wires or something. When this happens, I would like to send that signal to a computer/laptop which records it into some sort of database. The time between each connection would be the lap time, and the amount of connections would be the lap count. When this is recorded, I would like to present it on a monitor real time.

There's more, but that would be after I figured out a way to detect a signal to work with...

Have anyone done anything like that? or similar stuff.

I'm aware of that there exists stuff like this on the market. But that would require buying new track set etc. (that would probably be cheaper as well :P, but hey, who doesn't like to have something to do on their spare time ;))

UPDATE:
I'm adding a couple of pictures of the counter:

Beneath the car you can se a whit plastic pin. And right in front of the car, you can see a pin sticking out of the track. This pin is pushed to either side, depending on which direction the car goes, and ajust the counter with one.

Here you can se how the counter works.
(1) the car passes by, and pushes the pin
(2) the pin is then pushing an arm of some sort to turn a gear (3) - which is the counter.

Now, at the very bottom, it looks like there could be placed some sort of metal, or wires, that could send a signal to a computer when they touch.. But it happens very fast.

Hope this helps for clarifications..


texts: LM311 comparator : strange output levels

texts:
I have the following circuit, where I put R52 = R53 = 2700 Ohms :

Schematic http://free0.hiboox.com/images/5013/ac1bae22d71c2e3cc17b4ed3eda3090a.png

Triggering levels are of 1V and 2V approximately according to my computations, that is okay according to the following figure showing input in green and output in blue :

Output http://free0.hiboox.com/images/5013/92bf3b53a5576a7863be561d561b74fe.png

But what I find really strange is that the maximum voltage output is around 3.3V and not at 5V. How would you explain that ? And last detail : how would you explain that the output is not exactly at 0V when the input is high?

Thank you very much for your help.


texts: can I replace a 2n2222 transistor with a tip31c

texts: I have a TIP31c transistor, I need a 2N2222 for an Arduino project to drive small dc motors with PWM, I found both transistors are NPN, but I don't want to hurt my Arduino, is the swap possible?


texts: Why do TTL pulse generators generate an asymmetrical square wave (unlike CMOS)?

texts: I've read that the asymmetrical (about 1/3 mark-to-space) output waveform is due to input gate characteristics of a TTL inverter, but I want to know more about which characteristics of the TTL input gate causes this asymmetry. Thanks!


texts:
I just installed pyupdi and it works, but is very slow. I googled this and AVRfreaks says something about delay settings which seems irrelevant in my case (while the delay settings account for 30ms, I'm seeing something that accounts for 2s). In my case, what I see is that the readline() commands in physical.py are timing out. If I reduce the timeout value here:
self.ser = serial.Serial(port, baud, parity=serial.PARITY_EVEN, timeout=1, stopbits=serial.STOPBITS_TWO)

Then it speeds up dramatically and still seems to work. While it is much faster, timeouts are a symptom of some more serious problem. There should not be timeouts in normal operation. readline() should be used if the answer is newline terminated. Timeout is an error because there is no newline. (If there wasn't supposed to be a newline at the end, then a byte limit would be passed to read() so that it returns immediately when it has the expected amount of data.)
What have I not configured properly?


texts: Quad copter - from PID values to motor power

texts:
I am struggling with a completely self built/written quad copter I am working on.

I am working on the PID controller for balance, right now just with a P value and it only reacts on ROLL and PITCH to minimize potential errors.
I put the prototype on a box and use ropes to restrain it so it can not damage something/me.

My main question is currently related to the motor controll function.

Currently my PID controller gives me a number from -1024 to +1024 for each axis depending on tilt etc.

Currently I use this value, multiply it by 0.4 and ADD/DEDUCT it from the global THROTTLE variable.
So each motor receives THROTTLE (0-1000) and then depending on its position the PID value*0.4 is added/deducted to/from the THROTTLE.
1000 would be max power, 0 would be minimal power.

I am new to motor control with air vehicles and I think the way I control the motor is not right for a stable balancing.

What is a good way to control the motor power based on a PID value ?
So right now I use an absolute value based on what my PID returns, regardless of throttle.

Aside from the fact that I will still have to tweak that value as it would cause a crash on startup (the absolute value from the PID would be higher than the total throttle) I have a bad feeling in general about it.

My main concern is that this approach is fast in calculation (no divisions etc) but the PID values are always in the same range while the THROTTLE can be low (start). So on lower THROTTLE values the same tilt currently results in a stronger response than on high THROTTLE values.

I am sure someone with more experience than me could light me up how to properly tune the motor power based on the PID output.


texts: Using a trimmer pot to output a percentage of voltage

texts:
I am trying to do a project where I am getting two (or more) voltages and averaging them all out.  Then I would like to use a trimmer pot to adjust the voltage by a percentage, basically as a fine-tuning calibrator.

The elements I am using are 2 or more humidity sensors, They take a voltage in (5.5v) and give a voltage out (a percentage dependent on the humidity).  I will average those voltages out and want to have a relay switch when the voltage reaches a certain number.

I am new to this, so I assume if I get a 5v DC relay (OUAZ-SS-105D) I will need 5 volts to switch the relay over.  The humidity sensors will only output around 3-4 volts averaged.  I would like the relay to switch over when the average voltage output from the humidity sensors reaches 4.125v.

How should I approach this?  Does this make sense? or did I totally confuse you?


texts: BLDC - Single motor for a range of voltage supply with PWM

texts:
I plan to use a BLDC motor of around 1/3 hp supplied by a DC rail that is generated from AC mains. If the AC voltage is from 100 to 250Vac, I would have a rectified DC supply of from 141Vdc to 352Vdc.
The speed of the motor will be controlled by a purpose-built 3 phase electronic speed controller. In order to be able to use a single model of DC motor at any mains voltage I intend to use PWM to control the motor DC voltage  to be about 140 VDC. ie the purpose of the variable voltage control is to keep the DC rail at about 140 VDC when the AC mains voltage varies between about 100 to 250 VAC.
For example, when VDC=141V I will apply 100% duty PWM
and when VDC=353V I will apply 40% PWM.
Question:
Is this voltage control system adequate?
Can a single motor model be used this way.
______________________
Notes:
I have a single DC bulk voltage generated from mains, this is the dc voltage that would be commuted by the 3 pairs of high and low side IGBTs, not filtered, its 120 degree control where PWM only sets voltage.
The DC bus voltage ripple would be very low because I would use a pair of 470uF x 450V capacitors on the DC rail.
EDIT:
I will shown my current schematics regarding the BLDC motor, if that helps.


texts: How does this MOSFET/Op-Amp voltage regulator circuit actually work?

texts:
I am trying to understand the functioning of this circuit since I have read that it is appropriate for power regulation:

Here is the explanation that I have found:

The zener diode provides the reference voltage to the positive input of the opamp. Note that any other kind of voltage reference, such as a bandgap voltage reference would also work (it is actually better). A voltage divider composed by R1 and R2 provides a measure of the output voltage suitable for the opamp, i.e., if we want the output voltage to be k times higher than the voltage reference, than the voltage divider should divide the output voltage by k so that both inputs of the opamp can be equal for the desired output voltage. Then, the op amp supplies a voltage to the gate of the MOSFET transistor such that its negative input (the output voltage) follows its positive input (the reference), due to the beautiful effect of negative feedback. Any perturbation of the input current or the load current (or even others) will affect the output voltage, but the feedback loop will quickly adjust the driving of the BJT base to stabilize the output voltage at the desired reference.

But I pretty much am lost after they talk about the output voltage being divided down and then compared to a reference voltage. My question is, how does the comparing of \$V_\text{n} = V_{\text{out}}\times\frac{R_2}{R_1+R_2}\$ to \$V_{\text{ref}}\$ drive this circuit? I just find it so complex even though I know how to apply the equations to see which components I need, and I want to understand it conceptually.


texts: Why do I get a Top Level Design Entity undefined in my VHDL

texts:
I'm building an 8-bit register from d-type flipflops in VHDL for a lab exercise but I can't seem to diagnose a problem. Firstly I can't get it to compile because of the difference in types for the input clock. My project is called eightBitRegister so its not because my definition uses a different name. So if I change this to the correct type I get the error:

  Error: Top-level design entity "eightBitRegister" is undefined

The VHDL when this occurs looks like:

LIBRARY ieee ;
USE ieee.std_logic_1164.all ;

ENTITY eigthBitRegister IS
PORT ( Clock: in BIT;
       Data:  in BIT ;
       Q: out BIT) ;
END eigthBitRegister ;

ARCHITECTURE Behaviour OF eigthBitRegister IS
COMPONENT flipflop is
PORT ( D: in BIT ; Clock: in BIT;
      Q: out BIT) ;
END COMPONENT;

SIGNAL QOut: BIT_VECTOR(7 downto 0);

begin

Stages: for i in 7 downto 0 generate
LowBit: if i = 0 generate
    ff:flipflop PORT MAP(Data, Clock, QOut(0));
end generate;

OtherBits: if i /= 0 generate
    ff:flipflop PORT MAP(QOut(i-1), Clock, QOut(i));
end generate;
end generate;

Q <= QOut(7);
END;

However if I change it to this:

LIBRARY ieee ;
USE ieee.std_logic_1164.all ;

ENTITY eigthBitRegister IS
PORT ( Clock: in STD_LOGIC;
       Data:  in BIT ;
       Q: out BIT) ;
END eigthBitRegister ;

ARCHITECTURE Behaviour OF eigthBitRegister IS
COMPONENT flipflop is
PORT ( D: in BIT ; Clock,
      Q: out BIT) ;
END COMPONENT;

SIGNAL QOut: BIT_VECTOR(7 downto 0);

begin

Stages: for i in 7 downto 0 generate
LowBit: if i = 0 generate
    ff:flipflop PORT MAP(Data, Clock, QOut(0));
end generate;

OtherBits: if i /= 0 generate
    ff:flipflop PORT MAP(QOut(i-1), Clock, QOut(i));
end generate;
end generate;

Q <= QOut(7);
END;

It can find the top-level identity and get the error:

  Error (10476): VHDL error at eightBitRegister.vhd(22): type of identifier "Clock" does not agree with its usage as "bit" type

So whats going wrong?


texts: Force cellular modem to transmit at maximum power

texts:
I want to force my cellular modem to transmit at maximum power so that I can see if that is the cause of microSD card crashes that I have been experiencing in an embedded application.

My modem is a ublox U-260, and the AT command manual for it is here.

I know that the modem "throttles" its transmission power based on the intensity of the received signal (from the cell tower) so you can force the modem to transmit at maximum intensity by putting it somewhere with poor cell reception.

I have been unable to get my cell reception to be bad, however, as there are a number of cell phone towers nearby.

So, seems to me there are two options:

Physical solution: Attenuate cellular signals arriving from cell tower to modem via some type of physical solution
Software solution: Force the modem to transmit at maximum power levels regardless of strength of received signal by configuring it to do so via AT command (software solution)

So, anyone out there know how to implement one of these solutions?  I have tried building a faraday cage around the modem by lining the enclosure that it's in with aluminum foil and attaching an alligator clip to mains ground.


texts: Operating a 24VAC solenoid with a Triac. Protecting with TVS DIODE, RC Snubber or both?

texts:
As part of a project I am controlling 24VAC solenoid sprinkler valves like this https://rayshobby.net/wordpress/understanding-24vac-sprinkler-valves/ using a triac (BT1308W) http://www.mouser.com/ds/2/302/BT1308W_SER_D-111990.pdf and optocoupler (MOC3012) https://datasheet.octopart.com/MOC3011-M...-Fairchild-Semiconductor-datasheet-627034.pdf

My design is based on the reference circuit on the optocoupler datasheet for inductive loads:

My current design:

A few questions :

1)I added a TVS (D1) to protect from reverse voltage spike when the solenoid is turned off. Should I also add a snubber or with the TVS is enough? Do the protect from different things?

2)Is it a good idea to add a 10K resistor between triac's gate and VAC2?

3)I'm using the R19 and R20 values from the suggested datasheet circuit but, how are they calculated?

4)C21 is rated at 50v, is that correct?


texts: How do I recognize which type of bus bar these are? What are thecharacteristics of their circuit? They are so similar

texts:
I have a big problem with matching bus-bar names with their corresponding circuits.

For example, there are four circuits for 5 main types of bus bar, but I can't match the name with their corresponding circuit.  single bus-bar is easy to recognize, so I don't ask in this question.

The A type is the circuit of double bus:

The B type is the circuit of main and transfer bus:

The C,D,E type is the circuit of one and half, ring bus, and mesh bus:

As we can see some of them are very similar, so how do I know this bus is double bus, not main and transfer bus.  What are  their characteristics?

For example

Why all the A type are double bus, not main and transfer bus? If i erase the name like bus 1, bus 2 or main-1 and main-2
Why all the B type are main and transfer bus, not double bus?
Why is C-2 the  one and half bus, not mesh or ring bus?
How do I know the circuit is mesh bus bar, not ring bus?

If this is a basic question, sorry for asking this.  My book only tells me their corresponding advantages and disadvantages but dorsn't explain how to recognize them.


texts: I am not able to understand the difference between this two terms. I searched it online but did not get an appropriate answer anywhere.


texts: Transmitting VCC and GND signals for use with RS-485

texts:
The specific question I want to ask is whether I can transmit VCC(5VDC) and GND power signals for powering the destination circuit (in an RS-485 arrangement) or not.
The power lines will be grouped with the differential signals of the RS-485.
For background...
I am working on a project on a water level detector which involves communication between two microcontrollers over a long distance. As far as I have done research for my needs, RS-485 will be the best technique for long distance communication. It's between two building floors, as the level detector will be installed in the water tank on a terrace and the other monitoring MCU will be installed at my home, two floors below the terrace.
I will be using MAX-485 IC which connects with the MCU using DI, DE, RE, RO. It transmits the data over the differential lines A and B. My doubt is: can I power the MCU of the level detector using the VCC and GND signals that will be transmitted over two additional wires along with the differential signal lines of RS-485. There is no power source available on the terrace and I am trying to avoid using any batteries.
The RS-485 signalling will be using the UART protocol at 115200 bps typical.
The level detector circuit will be consist mainly of an MCU (probably atmega328p) and an HC-SR04 ultrasonic module. (I am open to using any less complex low-power MCU.) The atmega328p datasheet states 200 mA max DC current consumption and this website states that the HC-SR04 has 15 mA working current consumption.
Optionally, I am planning to include a small low power DC motor for operating a small plastic shutter for Ultrasonic module, and also some sensors like a Microphone and an Infrared TxRx LED pair. Hence the maximum supply current drawn by the level detector circuit will not exceed 500 mA, assuming a very lightweight low current motor.
I am a little bit confused with the below points:

5VDC-GND will interfere with the differential signals A-B.
The differential signals will interfere with the VCC-GND.
The VCC-GND signals will be affected/degraded due to outdoor environmental noise or long-distance transmission wires.
Additional: As per the need of a 4 Wire cable, I am planning to use CAT-2 Cable as I already have it in a length of 20m-30m. The CAT-2 cable is a two pair (Single strand thick copper wires) copper cable used for ADSL networking (broadband connection). Is it a good idea to use that particular type of cable or there is a better alternative for this need.

Any suggestion/solution within/out of the scope of my question is highly appreciated.


texts:
I am about to design an amplifier to J | K Thermocouples, but I have been unable to find a trustable equivalent circuit|model|specs for them.

I know a J Type Thermocouple has some general specs, such as, Iron-Constantan Junction|Wires, -210 to 1200 C Temperature Range, 50-58 uV/C Sensitivity, -11 to 60 mV Voltage Range.

Thermoelectric Effect expressions for Seebeck-Peltier-Thompson's roughly don't (or do?) give us clues about how to made an equivalent model far from its simplest equivalent circuit as a voltage source with a resistor.

But I would been unable to find other specs. In particular, I am looking for the following figures, or at least some reference|paper about them:

The maximum current one could draw from it (like an equivalent internal resistance?),
How it discharges with a resistive load (like a capacitor in parallel with a voltage source?)
The operating (recommended?) current under which it could operate without deviating (too much?) their "properties" (repeatability? sensitivity?),
The maximum current it could sustain without losing these "properties" permanently (solely through Joule Effect?).


texts: What makes intel capable of very high clock rates?

texts: What are the determining factors responsible for why Intel chips can clock at 4Ghz or higher speeds, while other processors such as ARM can't? Is it because Intel's state of the art fabs or is it the architecture of the x86? It hard to understand how a complex chip like the i7 can clock so high.


texts:
i recently posted a question, but didn't had an answer (my fault :) ).
my question wasn't straight-forward and clear.
so my final goal is to communicate between nodered (raspberry-pi) and my lg tv. I'm getting stuck on every step I take... So I will try to start step by step.
so to begin I wanna try controlling the tv with my windows laptop. I tried putty, but I think that's not the right program to use. my final goal is to controll the power-saving to turn the screen off, turn the tv on and off, and controll the volume.
I also want feedback so my home-automation knows the state and volume of the tv.
so I think it's maybe good to start with a right program on my computer to start troubleshooting?
so my first (and hopefully my last :p )question is: Is there anny good program that can send those commands and reicieve the data back from the tv? and second, it's not so clear what commands to send to the tv. in the text below is my previous question, are those commands usable?

I want to controll my LG tv using a raspberry pi running node-red. I'm havving troubles to get it to work. i readed the following LG RS232 Commands partially working, but I'm just getting stuck every time.

So what I have is a raspberry pi running nodered, i can connect nodered with the serial device ttyUSB0. (its a usb to serial adapter, with a crossover block female to female). i connected everything, but i get nothing out of my tv. I tried using putty on my windows, but i keep getting stuck :/ this forum is my last hope :p

edit: on page 142 of this PDF are the instructions for the tv https://gscs-b2c.lge.com/downloadFile?fileId=KROWM000259057.pdf

edit:I the tv uses rs232 the adapter I used is a usb to rs232 adapter :https://www.aliexpress.com/item/4001296387344.html?spm=a2g0s.9042311.0.0.27424c4dF9z9ML with a connector (female female): https://www.aliexpress.com/item/4000564124562.html?spm=a2g0s.9042311.0.0.27424c4dF9z9ML

my settings: baud:9600 data bits 8 paririty none stop bits 1 dtr, rts, cts, dsr are all auto

most cammands that i tried are gone, but i tried those ones: ka 01 ff[CR]

ka 01 ff

ka 01 00[CR]

ka 01 00

[K][a][1][ ][][00][x]

[K][a][1][ ][][01][x]


texts:
i have a laptop battery pack which i took apart and kept the batteries, hoping to make a battery bank, but the problem is i cant find any info on the batteries, they are all red and have a green mark on top indicating positive and there's some writing, so I've went into looking them up but nothing comes up, so i need help in figuring out what kind of battery is it. a 14500 or a 18650 cell, all i know is that the battery pack is a Rechargeable li-ion battery with 11.1v and capacity of 53wh, battery's voltages are between 1.2v - 3.8v

65MM for Height And 18MM for Diameter = 18650 Cell


texts: What is this green component from a camera flash unit?

texts:
I recently opened up an old camera. I tore it down to its flash unit.

I saw this green  component and I'm not sure what exactly it is.

It also has a small rod which fits inside the hole. When I opened up the camera in the first place, the rod was already inserted completely inside the hole. (Sorry no image of the rod because I lost it.) My guess is that it is some kind of inductor. However I'm not sure, because of the rod inclusion in it and also the entire component is dangling onto the copper wires, as shown in the image. I tried to Google some answers, but didn't find anything.


texts:
My laptop has this fan, which I want to replace. But before blindly replacing it and make it work I am curious to know what all signals are associated the four wires: Black, Pink, Yellow & Red.
I could not find a technical specification for this model (Asus BSB04505HA Fan).


texts:
I would like to create this 8 led beacon with only a single mode, that is turn 2 leds on at a time and move to the next one in a loop like shown in the picture below.

I want to achieve this without a microcontroller in the long run. I can use led drivers or shift registers or timers. I also have no problem programming the intitial setup using arduino but the project should not depend on a microcntroller for regular operation.

leds will be of 8mm straw hat size with 150mA each at 2.4V (red).
Power supply will be 2x AA NiMH cells.
No need of any input button function, if I power the setup then it should go straight to this function and keep looping until I power off.

Can it be done using 74HC595 or similar 74 series or should I go for LM3914  or is there any other simpler way? I understand that 74HC595 can't handle the high current requirement, which is why asked for alternatives.

These are the available IC's I can buy. the site also has other drivers.

Thanks in advance.


texts:
I have designed a 4-20 mA PID controller using atmega 328p, MCP4922(DAC), XTR115UA(4-20 mA current loop transmitter)
I used the circuits proposed in datasheets and the PCB and schematic files are linked(also 3D view is Available):
https://gofile.io/d/6gL8wP

please have a look and feedback about the layout or schematics.
will this work or fail?
is it helpful to use polygon pour both top an bottom layers and connect one layer to vcc and another to gnd?

here is the schematic and PCB:

this is where 4-20mA input signal comes in and is converted to 0-5V voltage with mcp601 op-amp and the result goes to uC.

5V supply:

the uC output is sent to DAC:

and the dac drives XTR115 current loop transmiter:

7809 produces Vloop and  4-20mA output signal goes to a 180 ohm coil.

this is the layout:


texts: How does ripple degrade electrolytic capacitors?

texts: How does excessive ripple current degrade electrolytic capacitors? What processes are involved and how do they work?


texts: single cycle vs multicycle datapath execution times

texts:
I have a question where I need to calculate the execution time for a program for single cycle and multicycle datapath. I think I may be doing it incorrectly since the multicycle execution time is longer than the single cycle.

So for single cycle the cycle time is 3.7ns with the longest step being 1.1ns.

So if I just have three instructions lw, and, or. For single cycle each instruction will be 3.7 x 3 = 11.1ns.

For the multicycle datapath lw = 5 steps, and = 4 steps and or = 4 steps therefore 5+4+4 = 13, 13 x 1.1 = 14.3ns. Which is slower than the single cycle. Am I doing something wrong or is this just something that happens ?


texts: SPI communication - bits per second vs Hz

texts:
I have been reading more and more about bandwidths and frequencies to try to solve the following problem, but I am only ending up more confused.  (I have limited electrical/signals background.)

I wish to communicate with an IC via SPI.  The device has a max clock frequency of 8 MHz.  I also need to use a logic level converter to convert between 5V micro-controller and the 3.3V device.  I found a Logic Shifter online that states "the bandwidth on the individual signal channels can range from 20Mbps up to 100Mbps... suitable for higher speed signals such as SPI."

I am confused how to interpret the bandwidth of 20Mbps to 100Mbps in terms of my clock frequency for SPI.

Does the Mbps limit my clock frequency choices, and if so, why?  From what I have read, bits-per-second and cycles-per-second measure different things, yet then I wonder why the manufacturer even bothered stating the Mbps range if it doesn't affect my SPI clock.


texts:
I want to have a battery bank of 9v rechargeables to power my system. I want to have the recharge circuit on the PCB.

My idea for the circuit is to linearly source current in reference to the deviation from 9v... That way it will trickle charge once the battery approaches full charge and I wont over charge the batterys if I leave the recharge source on.

Also, the charge current will be limited to whatever is recommended.

So my question is:

Is this a good recharging scheme?
What should I limit the max charging current to?
I've seen both NiMH and Li-Ion batterys, to they required different charging schemes?
Some batterys are 8.4v or something, will charging them to 9v damage them?

Thanks


texts: How do I find a commercial LED with 1625nm wavelength?

texts: I'm looking for a LED with an emission wavelength of 1625nm for a project, but have been unsuccessful thus far in my search. How would I go about finding a commercially available LED in this range? Is there a different subset of site to look at? I can only find LEDs going up into the 1300nm range.


texts: FPGA proper SDC constraint for hsync pulse

texts:
I have a design where video data comes in over the altera altlvds_rx lvds receiver.  One of the parallel bits that comes out the other side represents H-Sync which will show up for a few clock cycles every horizontal video line.  One always block in the design uses h-sync to count them so something like always @(posedge hsync)...

Now Quartus tells me it has decided hsync is a clock which I kind of get and then it tells me it is unconstrained.  What kind of constraint would I put here?  Do I declare it a clock and make it have a very unbalanced duty cycle?  Hsync period is quite large compared to the video clock but the positive portion of the pulse is only a few video clocks wide.


texts: What are the considerations for designing a capacitor bank?

texts:
I am trying to understand capacitor banks and capacitor discharge, and how to work out what I need to generate a short pulsed current.

If I would like to use capacitor discharge to produce a sudden burst of current in a circuit. This would be triggered by a MOSFET acting a switch connecting the load. What do I need to consider when selecting the capacitor, and what determines whether I need a capacitor bank, and what configuration it is, series or parallel?

I am looking at pulsing a 40 A current through an inductive coil (2 uH) and would like a rise time for the current of less than 1 us, which would require 80 V to drive it according to my calculations for the coil.

When considering the design of the capacitor load, I think the first thing is to make sure it can handle the voltage supply. The capacitance will determine the charge and discharge time in combination with the resistance of the circuit.

What other factors do I need to consider? What dictates whether one needs to create a bank of capacitors, or if a single capacitor would be sufficient?

And can the voltage source be left connected to the capacitor load, while the system is operating (switching)? Or would be a one-shot type of thing, charge the capacitor, disconnect, press the switch for the capacitor to discharge into the inductive load, reset?


texts: LiFePO4 Batteries Discharge Fast After Recharge

texts:
On my application I have four 200 mAh LiFePo4 cells, configures as sereies of two parallels, thus achieveing a 6.4V battery.

I understand this cells in series need balancing, I would like to leave this mattar aside for now, only keeping in mind that the cells are being balanced.

I'm drawing 130mA from the batteries for 1h, recharging them afterwards with ~10mA.

At some point they get stable at 3.45V, not the 3.6V it suppose to achieve. After this, with the same load, they discharge in minutes.

Any ideas of what could be happening for the batteries not achieving maximum charge voltage and discharging with such speed afterwards?


texts: What is the problem with connecting a negative voltage to an op amp's negative lead while the possitive one is grounded?

texts:
I'm reading a manual on op. amps that presents the following schematics:

And says:
[Context: Vin goes from -0.1V to -1V]

When Vcc is powered down while there is a negative voltage on the input circuit, most of the negative voltage appears on the inverting op amp input lead.
The most prudent solution is to connect the diode, D1 , with its cathode on the inverting
op amp input lead and its anode at ground. If a negative voltage gets on the inverting op
amp input lead, it is clamped to ground by the diode.

So, while Vcc is connected, the positive terminal will be positive, therefore the negative one will necessarily be so as well. Then, there is no problem with having Vin (negative) connected to it.
What I don't understand is the situation that the paragraph above describes. First, it tells that Vcc is powered down, in other words, the positive lead would be grounded. Therefore, Vin, which is negative, would be connected to a virtual ground and, for some reason, this requires to protect the op. amps. with D1. What exactly would happen in the negative lead if Vcc is 'powered down'?


texts: How to boost audio volume coming from a telephone

texts:
So I have this circuitry

Purpose is to connect the soundcard with a telephone to also play computer generated samples over phone.

It works with one drawback: The Headset's speaker is low volume. How to boost the Headset's speaker's volume? When picking up the telephone handset the volume is high enough but using the Headset's speaker it isn't.

4p4c goes to a telephone plug
LSteil means the part of the telephone that emits audio data, ie the speaker
Mikroteil means the part of the telephone that receives what is being spoken ie the microphone
KopfhörerEingang goes to a Socket to put a Headset's headphones plug in
the connector at the bottommost goes into the headphones output at a computer's soundcard
Übertrager 1:6 is an audio transformer/transducer
Masse is ground
Links is left
Rechts is right
Signal is signal


texts: Is it possible to execute two or several tasks in parallel with a microcontroller e.g. a PIC?

texts:
I am learning to program microcontrollers (with PIC18FXXXX) and what I have seen so far is that everything that is programmed within the main function is what is executed.

My question is, if you can make a call to a function that is outside the main and is running a scheduled task.

For example.
Press a switch and call a function void turn_on_led () and it activates an output of the microcontroller.

But it is not possible to do this.
What alternatives are there to do these things?


texts: Audio Amp-Calculate Current gain of a Push-Pull BJT Pair (and remove Beta Dependence)

texts:
I was designing an audio amp for a final project for an electronics course. We were given a very vague set of requirements and told almost nothing about our input signals or desired output minus relative gains.

This was our exact prompt:

  Design, build, and test a practical audio amplifier that would meet the following criteria(this portion is to be built in the lab).

  Input signal: Audio frequencies

  Voltage gain: 100 or higher

  Input Impedance: > 1 M Ohms

  Output Impedance: negligible

  Load impedance: 8 Ohm speaker

  State any assumptions you make, use discrete components (resistors,
  caps, diodes, transistors, op-amps), power supply use +/- 9 V

We've covered a fair set of transistor topologies, how to calculate gains and good design practices but we did essentially nothing on push-pull amplifiers, which is what my design is based on:

Reviewing some of the literature I came to realize this is more or less what a Class AB amp looks like, currently this design can do voltage gains of 1000 (something like 500-2500 if I put a variable pot 5k-15k) but one thing is bothering me. I have no idea how to calculate the current gain from the push pull, and I think that in this design there is a beta dependance on the output current. If so that's a pretty big problem since that means my current gain can wildly fluctuate and not even be the same between two transistors, and can scale unpredictably in different conditions.

My question is twofold:

How do I calculate my current gain for this circuit?

and

How can I modify this push-pull such that if there is a dependance on beta I can remove that dependence.


texts: Set feedback fraction of inverting input configuration

texts:
Suppose we have this:

simulate this circuit – Schematic created using CircuitLab
How can we set the feedback fraction of this closed loop configuration?


texts: Sourcing the correct Zener diode if it is even a Zener diode - markings 1.5KE33CA 0220K

texts:
I usually fix consoles, as a hobby more than anything, but have been asked to have a look at something as a favour. It is a simple PCB, but it is really old and the manufacturer has stated they no longer have schematics.
It is a control module for a plant vehicle. When plugged in, it blows a fuse in the vehicle. Having gone over the PCB, I think I have identified the issue. There are 2 diodes labelled Z2 and Z3. I believe they are Zener diodes. There is no band on the diode, but there is on the PCB. The top line of text reads 1.5KE33CA. The bottom row reads 0220K.
Would anyone please be able to tell me where I might find a replacement? They are both identical. I am only using a cheap Draper multi meter, but putting it in diode mode, one of the diodes appears to have an open line in both directions, or at least the reading drops from 1 to 0 in both directions. The other one remains on 1 in both directions.


texts: How to find the steady-state response from the impulse response

texts:
If we have an impulse response of a circuit which is u(t) and if one has the input and wants to find the output, we use convolution of the input and the impulse response to find the output, that is to my knowledge the use of convolution. If one wants to find the steady-state response to the sinusoidal input such as $5\cos(2t)$, why should we use convolution.
$$\mathcal{L}(u(t)* 5\cos(2t))=\mathcal{L}(u(t)) \mathcal{L}(5\cos(2t))$$

Does the steady case- response in this case mean the output? Second, if we have two cascaded circuits and to find the impulse response of the whole circuit, why do we have to convolve them. I would appreciate any answers.


texts: Why did this designer decouple to PE-ground?

texts:
I'm reading a schematic from a Commodore 128-computer. The schematic is designed in 1985 and contains a detail I've never seen before.

The picture shows the primary stage prior the transformer. L1 and C1 is a pretty standard EMI-filter, but C2 and C3 decouples the AC-lines to PE. I have never seen this before. I showed this to an electrician and an electronics guy, but none of them has seen it as well.

I don't remember the value of L1, but C1 = 0.1uF and C2 = C3 = 2.2nF.

Why are C2/C3 decoupled to PE? Why are they there, what are their purpose?


texts:
I have just bought the following 5-pin switches of eBay: here

Problem is that no spec came with it and I am now wondered if I can directly wire the LED pins to the main or if I need to add extra electronics.


texts:
I have a 5v dc supply generated from voltage divider and this 5v is used to drive L293d.

But the problem is as soon as 5v supply is given to L293d the voltage drops to less than 2v.

what could be the problem??


texts: Passive RFID tag - link between size of antenna and read range (detailed)?

texts:
It is often said that the smaller the tag, the shorter the read range.
Could somebody explain more technically in terms of radio engineering?
For instance: why the Hitachi's U chip cannot achieve a reading range greater than few millimeters? Maybe we can increase the amount of power of the reader?
Is there some real physical limitation caused by the size of tag or of its antenna that even smartest solutions cannot resolve?


texts: Transfer Function of Active Notch Filter

texts:
I have rigged up a notch filter from here. See below: -

Its the first circuit. Now I am trying to calculate its transfer function. I have calculated two equations, but I need the third one:

(Vin-V2)/(1/SC1) = V2/R3
(Vin-V1)/R1 = (V1-Vo)/(R2+(1/SC2))

V1 and V2 are the potentials at the input of the op-Amp.


texts: In a Generator, why when the Exciter voltage increases the Generator Voltage decreases?

texts:
I have a project where I have to build an electrical model of a generator with constant torque at 1500 RPM and simulate it in LabView.

I have a manual that describes some measurements that were made on the generator while operating at certain values, and something that is very odd to me is the fact that when the Exciter's voltage is increasing, the output voltage is decreasing.

Here I'll attach a table that shows some sample values.

Blue: Output Voltage
Green: Output Current
Red: Input Exciter's Voltage

I can see that the voltage-current relationship maintains a semi-constant power of 420kW Approximately, but when modelling this generator I don't know how to obtain a similar behavior like this one.

Also, Calculating the output impedance (with Z = V/I ) would help me when creating my model?. I considered that but I'm not sure where should I place it.