texts: Advice on choosing PCB for a 16A, 85V switch circuit

texts:
I am making a circuit that will allow a load to be configured in this manner:

Load is ON/OFF.
If OFF (controlled by a low-side FET making the circuit OPEN), the high side and low side can be configured to PU, PD, open, or to external load (external load connects outside of original circuit through banana jacks by connecting to High Side and Low side).

I should add that the MOSFET switching issues (flyback etc.) are not such an issue as this is to configure to a particular setting before power is introduced to the system.  If it needs to be changed, the system will be removed from power and then the switches will be actuated.

This circuit is specified to see 16A at 85V (although it is possible for this current to exceed this if someone is to incorrectly configure the driver so I considered a fuse on the HS, say 20-30A fuse).

I have no experience designing a custom PCB and thought to just buy one and solder myself, something like this https://www.mouser.com/datasheet/2/58/BPS-DAT-(BR1)-Datasheet-932653.pdf.

My concern from using the online PCB trace calculator estimates that the trace should be 10.8mm.  I don't believe the copper traces are that big on these PCBs, so do I make the solder joints to the board 10.8mm? Won't that short to other parts of the PCB at that width?

I guess my question boils down to implementation on the PCB.  I will use traces as little as possible and instead shorten the trace and use wire as much a possible, but not really sure if I am overlooking things or not in regards to the PCB.


texts: Help identifying SMD on USB Circuit (Wacom Intuos 5 - PTH850)

texts:
My Wacom Intuos 5 - PTH850 Tablet have one the following SMDs (the lower one, USB Data -) cracked.

Could you help me identifying which component is? I know each component bridges USB data + with ground (upper one) and USB data - with ground (lower one). None of them have any code (or at least I can't see any).

I will try to get a better picture asap.

FCC ID: https://fccid.io/HV4PTH850


texts:
I pulled a handful of electrolytic capacitors from a PCB and checked their capacitance on a multimeter. The number was not stable, but it also didn't average about some central value but rather steadily decreased. I didn't measure it for too long since the monotonic decrease was only a percent or so of the original value. Is this normal? Is this indicative of a bad capacitor? I included a bunch of relevant data below, the time table, the corresponding plot, and the first and last image I shot on my phone.

4700 uF nominal value

Time    Time[s] Capacitance[uF] %Decrease
8:31:21  00.00   4496             0.000 %
8:31:47  26.00   4443            -1.179 %
8:31:59  38.00   4440            -1.246 %
8:32:09  48.00   4438            -1.290 %
8:32:15  54.00   4436            -1.335 %
8:32:20  59.00   4435            -1.357 %


texts:
I wrote a simple program to toggle an LED on and off using the TIM1 interrupt on an STM32F0 discovery board.

CLK Freq = 48MHz
Prescalar = 48000
Auto Reload Register = 1000

Using the following formula to calculate the timer frequency:

Timer frequency = (CLK FREQ/ (Prescalar -1) * ARR)

In my case it is equal to 1 second. If I run this code without an interrupt, it toggles the LED on and off at 1-second intervals, which is what I want.

As soon as I use the ISR, my LED TOGGLE is really fast (approximately 500ms), if I make my Timer_Value = 60000

void TIM1_BRK_UP_TRG_COM_IRQHandler(void)
{
    Timer_Value++;

if(Timer_Value == 60000)
{
if(Timer_Change_Status == Timer_Deactive)
{
    SendBitToPortAndPin(LEDIND_Port, LEDIND_Pin,1);
    Timer_Change_Status = Timer_Active;
}
else {
    SendBitToPortAndPin(LEDIND_Port, LEDIND_Pin,0);
    Timer_Change_Status = Timer_Deactive;
}
Timer_Value = 0;
}
  // reload counter
TIM1->EGR |= 0x01;
}

In my main loop, I call the following function

void COnfig_Start_Timer(void)
    {
    RCC->APB2ENR |= RCC_APB2ENR_TIM1EN;

    TIM1->PSC = 48000;                          ///Load Prescalar
    TIM1->ARR = 1000;                           ///Load Auto Reload value

    NVIC_EnableIRQ(TIM1_BRK_UP_TRG_COM_IRQn);   ///Enable interrupt
    NVIC_SetPriority(TIM1_BRK_UP_TRG_COM_IRQn,1);///Set interrupt priority
    TIM1->DIER |= TIM_DIER_UIE;                 ///Activate Timer Interrupt
    TIM1->CR1 |= TIM_CR1_CEN;                   ///start Timer

    while(1)
    {

    }
    }

I would like to know what is causing my ISR to fire so frequently, when it should only fire once every second.  I have referred to my reference manual with no luck.


texts: PIC : problem with initialize internal RTC of PIC18F67k22

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I want to initialize the internal RTC of a PIC18F67K22 with some fix time and date. Time is set properly, but date is not set properly. The problem occurs in setting the year. year is not set to whatever we give to RTC.

Find attach below RTC code, which I write to initialize internal RTC.

 RtccInitClock();                                       //Intialize the internal RTC
 RtccWrOn();                                                //Write enable for RTC                              //enable RTCC output on RTCC output pin
 PIE3bits.RTCCIE=1;                                     //Enables the alarm interrupt from RTC

       RtccTimeDate.f.hour = 2;                             //Set Hour
       RtccTimeDate.f.min =  3;                             //Set minute
       RtccTimeDate.f.sec =  4;                             //Set second
       RtccTimeDate.f.mday = 05;                            //Set day
       RtccTimeDate.f.mon =  06;                            //Se month
       RtccTimeDate.f.year = 14;                            //set year

      RtccWriteTimeDate(&RtccTimeDate,1);                       //Writes the date and time read from the external RTC
      delay_ms(10);
      RtccSetAlarmRpt(RTCC_RPT_SEC,1);                      //Set the alarm repeat to every minute
      ALRMCFGbits.CHIME = 1;                                    //Alarm repeat infinite times
      RtccWriteAlrmTimeDate(&RtccTimeDate);                     //Writes Alarm date and Time
      mRtccOn();                                                //Enables the RTC
      mRtccAlrmEnable();

Is there any setting I may have missed?


texts: I just read the following article but didn't understand what they meant by foundry-specific.


texts: How would a mains transformer react to unfiltered "Class D" PWM sinewave on its primary?

texts:
Somewhat related to this question: How do I apply PWM signal to the primary side of a transformer to get synthesized sine wave at the secondary side? - specifically "Choice 1":

However in my case I don't have control over the PWM side of things. The characteristics are:

a PWM sinewave, waveform as above;
Vmax = 100V;
fPWM = 2kHz;
fsine = 50 — 200 Hz;
Transformer: cheap "E-I type" laminated core transformer for 230VAC mains (230 to 24VAC, 10VA) (not fixed in stone, see below);
The filtering inductor might be absent;
I do not have the PWM driver at hand, so I cannot experiment with it directly.

The aim is to have some much lower voltage on the secondary, in the vicinity of 10—20VAC. Pure sinewave on the output not required.
I'm wondering whether the ordinary type transformer for 230VAC mains (which is preferred because of low cost and availability) can be used in this scenario, or special type is needed because of the non-standard input? How would it react to this waveform? Especially if the filtering inductor is omitted?


texts: Burned Out Tantalum Capacitor Replacements

texts:
I have an old computer with a broken Miniscribe 8425SA hard disk.  One of the capacitors has burned out, and need some help finding a replacement.  Here are my questions:

It appears there are similar capacitors on the board which are marked "-A- 22uF 16V 89 2 8" (see pics below).  What does the "A" code mean?  I think I understand the rest (capacitance, voltage rating, date code?)
What ESR should I get?  Is the lower the better?
The capacitor appears to be 6.5mm X 4mm.  So the size code would be something like 6540?
Is there anything I can do to make this less likely to burn out in the future?  Higher voltage rating, say 25V?  Different capacitor type?  It appears tantalum capacitors are finicky and fail catastrophically.

Images:

Top view with identical (?) component

Side view, it looks like the capacitor was connected to the 12V rail.

Length of duplicate, in mm.

Width of duplicate, in mm.


texts:
I am using a 24V - 175A generator and I would like to use 37 meters of wire for my charging circuit. The voltage drop need to be less than 2V.

I did some calculations with the American Wire Gauge table:

For AWG 4/0 (0000):
R = 0.16072 Ohms/Km
Length = 37 meter
R = 0.16072/1000*37 = 0.00595 Ohms
Voltage drop = 175 * 0.00595 = 1.04V
Power = 175^2 * R = 175 * 175 * 0.00595 = 182 W

For AWG 2/0:
R = 0.16072 Ohms/Km
Length = 37 meter
R = 0.255512/1000*37 = 0.009454 Ohms
Voltage drop = 175 * 0.009454 = 1.65V
P = 290 W

My question is: What will be the change of temperature of these wires? I don't want it to burn...

If you can explain (mathematically) the calculations of the temperature, I would be very happy.

Thanks!


texts: Lower Voltage Power Source with Higher Voltage Components?

texts:
I have very limited knowledge of electric theory and circuitry, as I was a Computer Science major and only dabbled in it as a hobby, but I'm working on a Halloween prop and haven't done anything with electronics in a while and need some advice on one of the components in the circuit.

What I'm designing is a Skull Staff that will have LEDs in the eye sockets, and I want to have a toggle switch on the staff to turn them on and off.

So far, I figured I would use a 9V battery and have two green LEDs in series. I was going to use 330 ohms of resistance, but I only have 220-ohm and 150-ohm resistors, so I figured I would use those in series to get 370 ohms.

I've been looking on Amazon (not the best source, but I have Prime, so free 2-day shipping) for toggle switches I could use, but most switches I see are rated 125 V / 6 A, or 12/24 V and 30 A.

Can a lower voltage power source be used on a component rated at a higher voltage and amperage?

Also, can anyone recommend a specific toggle switch I could use? Preferably small. I need to embed it in a PVC pipe that's 1" in diameter.


texts: Powering a 3 phase 230VAC motor with 28 12V batteries wired in ceries

texts:
Mechanical Engineering student here.
I'm a part of a senior project team that is trying to run a 40 HP 230 VAC three phase motor with a 40 HP VFD for a hydraulic pump.
Our plan is to wire 28 lead acid batteries (12 V, 81 Ah) in series to get up to 326 V and connect it to the DC common bus of the VFD.
Now, I think that this sounds unsafe and unsure if it will work, but the only issues that I have come up with are the danger of charging the batteries and the voltage drop when running. The EEs in our group countered with this:

Charging: They will create a box with a bunch of relays that will switch the batteries from series  to parallel for charging.
Voltage Drop: Voltage input rating of the VFD is +10% to –15%, which means it needs anything from 195.5 VAC to 253 VAC. So theoretically, it needs 276.5 VDC to 357.8 VDC. Even if the batteries drop to 10 V, the VFD would still run.

However, I still don't feel safe with this set up. I can't find a DC to DC converter or a DC to three phase AC converter with our power and voltage requirements. Is there anything else that I am not thinking about?
Links:

Motor (324THFPA8038)
VFD (FRN040G11S-2UX)


texts: What is a good melting point for a lithium battery contact fuse?

texts:
Tesla uses a fuse on every battery for their cars, and many fusible alloys melt from 50 to 90 degrees.

because the fuse is welded onto the battery it wouldn't matter what the fuse current was, you could have a large wire capable of high currents which would melt only when the battery rises over a certain temperature.

What would be better, a lithium battery welded fuse that melts at high currents, or at high temperatures?

What would be ideal fusing temperatures for both scenarios?


texts:
I'm trying to get the device ID out of dataflash memory using an mbed. I'm trying to understand this table that is in the documentation for the memory. I understand that ABh, 90h, and 9Fh are the instructions that have to be sent to the memory to get the ID. What is listed under them? Are those the codes that will be returned? What is (ID7-ID0), (ID15-ID0), and (M7-M0)? What is EFh?

The full datasheet has been delisted from the manufacturer website, but it's still available here on octopart.


texts:
I am having trouble where to start an attempt at sketching the Bode plot for the following transfer function:

I know I need to rewrite it into its proper form, making both the lowest-order term in the numerator and denominator unity... but the denominator is what's throwing me off. If I keep all of the terms separate in the denominator, how can I find the poles of the transfer function?


texts: Serie, parallel and other configurations (relative to small signal) of capacitors in amplifiers - poles and zeros

texts:
When I study frequency responce of amplifiers, I must understand if capacitors are in serie, parallel etc. relative to input small signal (in my exercises there is always only one input small signal). So far I learned that:

a capacitor in parallel to the input small signal introduces an infinite zero and a finite pole;
a capacitor in serie to the input small signal introduces a finite zero (equal or not equal to 0) and a finite pole;
a capacitor in other configuration introduces a finite zero and an infinite pole? Is this third point right?

For example, if I consider the following circuit:

the capacitor C2 is in parallel to the input small signal, in fact for w=infinity the vu=0. Is the capacitor C1 not in serie or parallel (for w=infinity --> vu is not 0; for w=0 the vu is not 0)?

Thank you in advance.


texts:
I'm trying to drive LEDs for the purposes of a strobe light.  I'm planning on driving the LEDs at ~60 fps, and for ~100 us pulses to provide very sharp strobe images.

If the pulses are very short and infrequent, you end up needing extremely bright LEDs to make up for how infrequent the LEDs are "on" (same as if you were PWM'ing them with a 0.1" duty cycle or so).  The typical solution is to overdrive the LEDs by a large factor -- I've read papers about putting 1000x the rated current through an LED, which won't damage the LED as long as it cools for sufficiently long times.

To accomplish this goal, I put together this circuit:

The LEDs are connected via a connector at P4 (labelled "LED_1").  I currently have 3x White LEDs with a forward voltage of 3.5 volts placed there.

I would expect to see (12 Volts - 3*3.5 Volts) = 1.5 Volts across the resistor R5.  With a resistance of 0.02 Ohms, I would expect to see 75 Amps placed through the LED -- however, while running the circuit, I find that it's only about 1.3 Amps, with a voltage of 150 mV or so placed across the resistor.

I'm using a FET Driver to drive the MOSFET, so it doesn't seem to be an issue of it not being fully turned on.

Can anyone help me understand why this is?

thanks!


texts:
Possible Duplicate:
  Using a motor to open doors

iv attached a picture of what im trying to do. Open a vertical door on my wood work project.

i just want to know what methods i could use to do this;
 - like useing a servo and a rod
 - Something else
thanks


texts: Do 0-10V proportional valves and dampers require a sourcing or sinking controller?

texts:
A 0-10V controller can use either sourcing or sinking to set the control voltage (see Wikipedia 0-10V Lighting Control, for example).  For sinking control, the controlled device provides a high impedance voltage that the controller sinks current from to generate the desired control voltage.  For sourcing control, the controller provides a low impedance voltage to drive a high impedance input on the controller.

What type of 0-10V control do HVAC proportional valves and dampers use, sourcing or sinking?

This is a datasheet for a proportional valve: Siemens SSA61

This is a datasheet for a damper actuator: Johnson Controls EDA-8102


texts: What is the best way to measure voltages higher than the ADC internal reference?

texts:
Let's say an ADC has an internal voltage reference and I want to measure voltages greater than that reference. I can use a voltage divider on the input(s) to limit my max input signal to said Vref. Now let's assume the ADC allows for an external voltage reference. I can use an external reference that matches my max input signal.

Hardware is not my thing, but I see a couple trade-offs right away:
1) The voltage divider(s) are significantly cheaper
2) If there are more than a few inputs, the external Vref requires less overall components

Ignoring those (if you want), which is the better approach?

Adding info for The Photon: 12 bit ADC. 0-5V input signal.


texts: Is there an upper limit of voltage than can pass through a wire?

texts:
The way I understand it, electric wires heat up because there is too much current passing through them. There are tables for various materials, how much current can pass through a given cross-section without a significant heat-up. That's also why we use high voltage in the big power lines to transfer a lot of power - this allows us to make the wires thinner (cheaper).

But is there an upper limit to this trick? Would it be (theoretically) possible to raise the voltage to petavolts, and pass all the power of the entire planet through a wire no thicker than a hair?

Added: To clarify, I'm wondering how far the voltage can be pushed, what the problems would be (ok, so insulation is the first one), and if there are any theoretical limits that cannot be surpassed no matter how much technology improves.


texts: Can the flux (not flux density) of a transformer be controlled so as to achieve constant voltage output with varied loads? For example, increasing the flux slightly when the load is high.


texts: I am trying to play music from a PIC microcontroller using a DAC.  I have seen other similar questions, but they use parallel interfaces and I am hoping to save pins with SPI as the interface.  I saw this chip MAX541CCPA and thought it looked good, but I don't know what specifications are important when choosing the DAC.  I figured a low settling time is probably important.  The music is stored as mono 16 bit PCM.


texts: Why do I first need to set a value and then direction of the GPIO in an embedded processor?

texts:
I have a full time job as a firmware engineer. I've recently been given a task to review GPIO configurations and change the settings as needed. I found a few pins that were incorrectly configured so naturally I reconfigured them, however I was told I did it in the wrong order. Here is what I'm talking about:

  Before: GPIO1.direction = INPUT;

  After: GPIO1.direction = OUTPUT; GPIO1.value = 0;

However during the code review I've been told that I need to change the order of initialization to the following:

  GPIO1.value = 0; GPIO1.direction = OUTPUT;

In other words set the value first and then set direction of the pin. I've also been told that this is how it needs to be on the modern processors because they use two registers, one for input and one for output, however old processors use only one register, so the order of operations wouldn't matter.
(Note: Modern = ARM Cortex M3 and above, Old = Intel 8051)

I asked for a better explanation at work, but I couldn't get a good answer. That's why I decided to ask here.

So here are my questions:

Why does the order of initialization matter on the new processors?
Why does the order of initialization not matter on the old processors?
What two registers are they talking about in the modern processors?
What single register are they talking about on the old processors?

If someone could provide some sort of a diagram, that would be even better.


texts: Mixer Audio output xlr small contact with pin power suply of guitar pedals , possible damages?

texts:
Last night after a gig my audio Mixer output cables has had a small contact with the pin of the power supply of my guitar pedals that was on electricity.

The mixer was not on electricity but the VU meters of the mixer detected the contact.

The mixer is working normally, but may have caused damages to the mixer this small contact of the mixer audio output with the power suply of the pedal (12V), (i have put a picture of how was the contact) ?

I am very aware of this because I use this mixer for gigs and would not want it to fail during live performance.


texts: I have seen several products ( such as the pitft for the raspberry pi, and most other small tft screens) which use a 3.3V regulator on the 5V power rail to provide power to the 3.3V system. In some of these products, given that they are breakout boards for systems which have a 3.3V power rail which can supply the needed current, it seems that the extra 3.3V regulator could be omitted. Is there any special reason why it might be beneficial to include this external regulator?


texts: Jumper Setting Modes in PIR motion sensor

texts:
I was going through the data sheet of the PIR motion sensor when i saw this:

So what i couldn't understand was the H and L trigger and how to change from H to L or L to H (like to do we have to provide HIGH to the H trigger to activate it or something else). I found a little bit of description here but i'm not fully able to grasp this:


texts:
Current rating: 3A @ 125 VAC, 1A @ 250 VAC

What can I read to understand these ratings better? What exactly does it mean?

They're used to rate this Momentary N.O. Raised Push Button Switch.


texts: Holed none-copper clad green epoxy glass soldering problem vectorbord model

texts:
TO MODERATOR

Tis question is different from the post from Use for trackless / bare stripboard?  DO NOT MARK AS DUPLICATE AS HAVE MANY PEOPLE LINK TO THIS PAGE TO ASSIST ME WITH IDEAS.  Placing a fake link  is completely impolite , rude an uncalled.
................................................................
I am very new at electronic soldering.  I got a different type of prototyping board which can not determine how to properly solder components.

It is a Vectorbord green epoxy board with holes but no copper clad.  I tried to solder with flux and solder from Radio Shack but the solder does not bond to the board.  I have look the specification but I am to able to determine if these type of board are for etching or just need a specific solder and flux.  Please help.


texts: How to find Vce SAT in NPN transistor datasheet

texts:
I am trying to find out the VCE value when the collector current is 150 mA (Controlled by the load). the base current is 4 mA. What is the VCESAT value when the base current is 4 mA?
part: BC817-40

Datasheet


texts: PIC18F1320 with 4 separate PWM channels and C18 compiler for an RGB LED

texts:
I'm pretty new to microcontroller programming and I find the lack of documentation on certain features of PICs with C18 compiler frustating. I've been trying to make a simple 3-color-led light up using PWM for each channel but I can't seem to figure out how to use the ECCP enhanced PWM feature of PIC18F1320.

I've got a couple of other PIC18Fs (2550, 1320, 4450 to name a few) so trying other ones is an option, but I specifically got the 1320s because they had Enhanced PWM, Page 115 in the Datasheet.

I've got some code to slowly pulsate 1 led channel using normal PWM, I've attached it here. Im using the pwm.h include and its helper functions, but people have mentioned just setting the registers manually. Im confused as to how I would set the specific ones the manual mentions, they are in a format Im not used to, something like CCP1M<3:2> =/

I keep finding scraps of useful material out there and constantly learning about whats inside these things, so hopefully with your help i'll be able to make sense of all of this and make some basic code to light up this damn LED =D


texts: I am in the process of checking if my SiC mosfet is damaged or not. To do that, I take a multimeter and measure resistance between Drain and Source. The resistance starts with an order of 10M but increases upto 70 M and keep going. Am i right in thinking that this is because the output capacitance is getting charged with multimeter ion turn increasing the resitance? Also, when I check the voltage between Drain and Source, the reading is 2.2 V going down, So I remove the multimeter, put it back again and it starts again from 2.2 V (even after discharging with an external resistor of 110 ohms). Please help me understand what is happening


texts: Does this connector exist and if so what is the correct name?

texts:
Please see picture.

2.54mm pin pitch.
8 pins, 8 'ways'.

So, "1x8" I think is the right way to state it?

I am trying to find a connector / header / whatever-name-is-correct to change direction 90 degrees in the vertical direction rather than on the board-plane direction like is commonly seen and easily found by searching for 90 deg headers.

I have searched using many search terms including 'upstand' 'vertical' '90 deg' 'board to board' and more that seemed like 'maybes'. Scrolling through many hundreds of pictures with no luck, so am desperate now and posting here.

I have seen board to board connectors like what I want in older electronics (a TV set, an ancient copier) though the ones I saw did not have a plastic housing at the pin end, only at the 'ways' end, and those were both 16 or more pins not 8 like I need.

Please tell me the correct name for such a connector, if they exist?


texts: Typical dissipation constant of average thermistor?

texts:
What is the typical dissipation constant of average thermistor? I.e. how much current I can feed to thermistor without significant self-heating?

I know that I can measure exact value for particular thermistor, but I wondered whether there was some kind of typical values like 3 mW/°C, "1ma should be ok" or so.


texts: Can throwing charged capacitors cause magnetic fields?

texts:
Since current is just buckets of charge passing through a point in space per unit time, and a capacitor is a literal bucket of charge, I had some questions in mind.

Is throwing a charged capacitor considered electrical current? Like if the capacitor is say 1 inch in length, has 1C of charge, and is flying through the air at  100 inches per second, does that mean 100 amps of current?
If so, would magnetic fields be generated? Would it actually take more effort to throw a charged capacitor than to throw an uncharged one, since the supposed magnetic field stores part of the work done in throwing?
If the capacitor is left on the desk, and an observer moves instead, would he/she see magnetic fields, but a stationary one doesn't?

I know this is silly and trivial, but I don't have iron filings and a large supercap.


texts: Clock source for STM32L433 does not switch to PLL

texts:
I am trying to switch the cyctem clock source on the stm32l433 MCU from the MSI (set by default) to PLL.
My code for setting up the PLL & switching the sysclk source is this:
/* Set latency to 4ws to support up to 80MHz */
SET_LATENCY(FLASH_ACR_LATENCY_4WS);
while ((FLASH->ACR & FLASH_ACR_LATENCY) != FLASH_ACR_LATENCY_4WS)
    ;

/* Disable PLL, enable HSI16 & HSI48 */
RCC->CR = (RCC->CR & ~RCC_CR_PLLON) | RCC_CR_HSION;
if (!(RCC->CRRCR & RCC_CRRCR_HSI48ON))
    RCC->CRRCR |= RCC_CRRCR_HSI48ON;
/* Wait for PLL, HSI16 & 48 */
while (!(RCC->CRRCR & RCC_CRRCR_HSI48RDY) || !(RCC->CR & RCC_CR_HSIRDY) || (RCC->CR & RCC_CR_PLLRDY))
    ;

/* Setup PLL */
RCC->PLLCFGR &= ~(RCC_PLLCFGR_PLLREN | RCC_PLLCFGR_PLLR |
                  RCC_PLLCFGR_PLLQEN | RCC_PLLCFGR_PLLQ |
                  RCC_PLLCFGR_PLLPEN | RCC_PLLCFGR_PLLPDIV | RCC_PLLCFGR_PLLP |
                  RCC_PLLCFGR_PLLN | RCC_PLLCFGR_PLLM);
RCC->PLLCFGR |= (78 << RCC_PLLCFGR_PLLN_Pos) | (0b11 << RCC_PLLCFGR_PLLM_Pos); /* Set up PLL multiplier to 78/4 */
RCC->PLLCFGR |= 0b01 << RCC_PLLCFGR_PLLR_Pos;                                  /* Set PLL division to 4 */

/* Enable PLL & wait for it */
RCC->PLLCFGR |= RCC_PLLCFGR_PLLREN;
RCC->CR |= RCC_CR_PLLON;
while (RCC->CR & RCC_CR_PLLRDY)
    ;

/* Setup system prescalers */
RCC->CFGR &= ~RCC_CFGR_HPRE;                                     /* Set AHB prescaler to no division */
RCC->CFGR = (RCC->CFGR & ~RCC_CFGR_PPRE1) | RCC_CFGR_PPRE1_DIV4; /* Set APB1 prescaler to 4 */
RCC->CFGR &= ~RCC_CFGR_PPRE2;                                    /* Set APB2 prescaler to no division */

/* Set PLL as sysclk source & wait for it */
RCC->CFGR = (RCC->CFGR & ~RCC_CFGR_SW) | RCC_CFGR_SW_PLL;
while ((RCC->CFGR & RCC_CFGR_SWS) != RCC_CFGR_SWS_PLL)
    ;

Everything runs fine until I try to set PLL as the sysclk source.
After I set SW bits to PLL, i need to read the SWS bits to make sure that the hardware has applied the change, and when the program reaches the while loop to wait for the SWS bits, it hangs and never exits the loop.
Am I doing something wrong or in the wrong order? Is there any other register I need to set before changing sysclk source?
I have tried switching to HSI16 instead of PLL and that clock source does work and the MCU exits the while loop almost immediately.
I have checked that both my PLLN and PLLM values are in the acceptable range and thet the VCOin and VCOout are in the acceptable frequency range too.


texts: How to calculate the time of one single tick on microcontroller

texts:
I have been in Embedded system for 8 months. I have worked application part more compare with low level. I have basic questions on systems ticks,

How to calculate the system tick of Timer, if I am starting the Hardware Timer of a controller for generating any delay. If I am having the 16-bit timer for example and I configured the system clock for 8MHz. As per my knowledge the single tick will be T=1/f. Then one single tick will take 0.125 microsecond. Is this correct? or any other dependency to calculate it. Whether this calculation will vary with controller by controller?
Is there any way to configure the clock(eg 1MHz) for only Timer or any other peripheral with out changing the System Clock(eg 8Mhz)
If controller goes to low power mode(typically a changing of power mode). The timer resolution will also change? whether I need to change the setting of Timer for each power Mode.


texts: What are 12.000393 MHz crystals used for?

texts:
I found them on www.digikey.com, and they're apparently made by different manufacturers, so there must be some use for them. What are they used for?

edit
and why? The 2400 baud modem doesn't offer an explanation: a 12 Mhz crystal is better for that than the 12.000393 Mhz.


texts: Drive a 9V latching solenoid valve with 5V pulse

texts:
I have a latching solenoid valve laying around, the original controller is broken and I'd like to make it work using a uC. I don't have the electrical specs of the valve. The broken device was using a 9V battery so I guess the latching valve works at around 9V. When I try it on my workbench without water and apply a short 5V pulse it clicks in and out so it looks like working. But I'm not sure it will work when there is water pressure. Anyone has experience on these type of valves? Is there any dependency between the applied voltage and the water pressure? Or can I make the simple assumption that if it works without water it will also work with water pressure?
Thanks in advance for any help,
Pedro

EDIT: Add some photos

Valve:

Controller:

The controller has two 9V PP3 connectors for two 9V PP3 batteries. It looks like they are using a transistor to select the battery, so they might be with reversed polarity, in order to make the positive or negative pulse to the valve.


texts: Requirements on dielectric strength and isolation between the conductors in an Ethernet transmission line with PoE

texts:
I am trying to find out what the requirements are on dielectric strength and isolation between the conductors in a Gigabit Ethernet transmission line.

A first place to look would of course be the TIA-568 standard, but I can't afford to buy it.

Second place to look would be in a manufacturers datasheet for a Cat5e cable like this one, which specifies the following:

  Dielectric strength conductor-conductor and conductor-screen (2 seconds) : 2.5 kV DC

That's what I'm looking for, but the problem with this is that the manufacturer might have taken some headroom over the minimum value allowed by any possible standard. So that's a dead end, as I see it.

Are there requirements on this property in any standard? If so, which one and where to find it?

Thanks in advance!


texts: Buck/Boost Converters-- What's the 'cost'?

texts:
I am trying to source (hopefully) a single power supply for my present project. From this single source I was thinking of using appropriate buck and boost converter circuits to fan out the various voltages I need.

I understand that with something like a basic DC voltage regulator, your 'excess' is basically dissipated by heat (which you have to watch out for/ensure to control).

Seeing with almost everything in engineering there is inevitably a 'trade off', I was wondering what the case was in terms of 'buck and boost' ?

For one, from some circuits I have looked at, I can obviously see they don't have 100% efficiency (though many are not all that bad)-- Though at the same time with the right IC these circuits are much simpler than the straight 'power/transformer' circuitry that would otherwise be needed.

In this sense, I am wondering what is the 'cost' of buck and boost-- is heat still a major issue ? Is it only a matter of a certain loss of efficiency ?

A bit of a basic question I know, but still trying to wrap my head around this.

Thnx.


texts:
This is background: I have a self-made PCB, which is used to connect the camera via the CameraLink interface.
When I connected everything together, it turns out that the camera is signalling me via LED an error associated with the received command.... but I don't send anything yet.

I came to the conclusion that maybe if I send the correct command to it (which I am not 100% sure, I hope I have understood the documentation), it will be accepted by the camera and I will receive a confirmation. Unfortunately, the camera did not respond at all and every few seconds it shows the same error again and again. As if it hadn't noticed the command at all.

This is the problem:
Commands are transmitted via UART standard via LVDS DS90LV011A driver:

With an oscilloscope I checked that the correct signal is coming from the control unit to pin 5. Therefore, I would like to check whether I have the correct signal at the differential output. How to correctly check such a signal with a simple oscilloscope with standard probes?


texts:
how to determine the continuous time loop filter transfer function from discrete time loop transfer function.

Loop filter transfer function is

If DAC is of NRZ type  with 3 bit input how to get the transfer function in continuous domain?
Can I use ZOH for a 3 bit DAC?
Can I use MATLAB d2c command for this conversion?


texts:
My Lenovo SL500 AC Adapter has broken and left me without a way to charge my PC.
It's Output Specs were the following:

20 V
4.5A (4.5A)
90 W

I had another Lenovo AC Adapter for a different PC of mine's, though having the following Output Specs:

20 V
3.25A (3.25A)
65 W

It is clear that the maximum current it can provide is 3.25 A, while the previous one could provide up to 4.5 A.

I would like to know two things:

how can I measure current request from my laptop?In order to assess if the working adapter will be able to provide it.
are there any counter indications on using this adapter instead of the original one?Can any damage occur to the PC or to the adapter by having a under amperage?

Thanks for any help provided


texts: software for obtaining differential equations for circuit simulation

texts:
Does any of the common circuit simulation software provide the system equations? Deriving a system of 1st-order differential equations for a circuit by hand is kind of a pain. And yes, I know that the simulators will actually run the simulations for me, but there are some cases where I'd really be interested just to see what the equations are. Which, if any, circuit simulators would provide them?

EDIT ..

What I am specifically looking for here is, I would like to be able to enter my circuit into the software, just like you would do for simulation, but besides run the simulation, I'd also like to have the software show me the equations that it has derived and uses to run the simulation - the system of differential equations that says what the rates-of-change of the system state variables are. This could be a system of equations or it could be in matrix form, doesn't matter.


texts: Why are VHDL "external names" that are used to create alias to signal at another level of hierarchy, not synthesizeable?

texts:
I am using Quartus 18.0 and have set the settings for VHDL-2008. However, when I try to compile a trivial project where one "external name" signal exists, I get this error:

Error (10500): VHDL syntax error at LED.vhd(16) near text "<";  expecting an identifier, or a string literal

This proves that "external name" which is declared using << and >> symbols, cannot be used in synthesizable code. I have confirmed that this fails in Microsemi Libero and also in Intel Quartus Prime Standard. My question is why?


texts: Power drop on AC-DC converter due to relay

texts: A uController circuit is powered with an AC-DC converter. This circuit in turn acts on some relays to turn on and off some loads. We have two bi-stable relays and another simple relay (Omron G5DN-1A) . The bi-stable realays cause no problem, but once the Omron relay is connected, power on the DC side randomly drops every and causes the uController to reset. It is not necessary for the relay to act, doesn't matter whether its open or closed or even if the relay has or has not any loads at its output. Just with the relay being connected on the PCB. This happens with a cheap AC-DC converter we bought on Aliexpress  but not with other more expensive converters like  VSK-S1 . We have added some capacitors at the 5V output and and input filter and the voltage drop is reduced but not eliminated.. Any ideas? We think maybe the converter used is too high output current for our consumption (700mA vs 50mA). the other we bought and work are 200mA.


texts: What is the difference between BAW and SAW?

texts:
TI has recently (?) released some BAW (Bulk Acoustic Wave) based resonators, but SAW (Surface Acoustic Wave) devices has been around for ages. Most often SAW are found in mobile RF filters.

This gave me a littlke bit of insight, but not enough to claim I understand the diff.

What is the difference between devices operating with SAW and BAW?


texts: Why does the small signal analysis work? (Intuition)

texts:
Consider the Large and small signal model of the MOSFET amplifier,

simulate this circuit – Schematic created using CircuitLab

How is this transformation valid, I get the linearization of the MOSFET, but then how can a source become a short and how can we reason the simplifications of other elements. I mean, the original circuit looks totally different from the small signal model. Please provide an intuitive answer, as I get the math part (i.e.) for small signal variations, the behavior of various elements are studied and then approximated, My question is how is this valid? For example, the small signal model of a resistor is simply the resistor itself because the resistor produces a corresponding voltage drop during the small wiggle that we supply, similarly wouldn't the Voltage source be unaltered during the 'wiggle', so shouldn't the small signal model of the Voltage source be itself ?
Is there a non-mathematical explanation for shorting voltage source during small signal analysis?


texts: Choosing a Solid State Relay for an AC air compressor application

texts:
I just started working with/reading about solid state relays last week, so bear with me here.

I have an air compressor -- 120 V | 60 Hz | 2.8 A -- that I would like to operate with a control signal from an Arduino (to turn on the SSR to power the compressor).

The input voltage is 115 VAC from a line filter -- at 115/250 VAC, you get 10 A rms max.
The AC voltage after the filter will also be converted to 24 V, DC (via an open-frame power supply).  This 24V will power a myriad of other components (I can provide a list if necessary).

In certain scenarios, the compressor will run along with the 24V DC-supplied components.

Given these parameters, what should I look for in an SSR?
What kind of tolerances need to be taken into account with respect to making the SSR work properly or damaging it?

Thanks for any info you can provide.

Anthony


texts:
I'm trying to make an IR receiver-emitter pair to provide the signals for a larger circuit. I've used the standard circuit for the receiver emitter pair. I've enclosed a picture of the circuit.
Is there any way for me to test whether the LED is working fine at the current I am sending through it? The cause of my concern is that I think I may be spoiling the LED while soldering it. Also, what would be a typical operating forward current for the LED?
Any advice would be extremely welcome. I'm a second year undergrad of EE. ( I'm stating this because there has been some concern lately about the competence of users.)


texts:
How exactly does a comparator work?

Comparators have many uses and its concept is not too hard to grasp. What I don't understand however is how exactly it compares two voltages.

How does it know that a certain voltage A is greater than a voltage B? And why does that trigger the comparator?


texts: How is the signal observed from electrode and electrode impedance is affected if we clean one of the pair of Ag/AgCl cardiac electrode by scraping it with steel wool until it was shiny and bright


texts:
Posting here, since Nordic DevZone is broken for me (Made a long post that didn't upload, just kept loading).

I am currently approaching this from HW point of view (I personally not developing firmware).

Using this scheme:

Before nRF goes into low power mode, the nRF_COIN_EN is pulled high to attach the coin cell. Every other GPIO is pretty much disconnected (not to consume anything else).
When 3.3V disappears, the Vcoin is the only thing keeping nRF alive. nRF comes back up when 3.3V is applied (detecting this via nRF's LCOMP).
RTC keeps track of time, when Vcoin is above 2.5V (nRF sees ~2.4V). Under that RTC data is gone.

Shouldn't it be that the nRF is able to run even down to 1.8V...? but I can't seem to get it so.

The current draw is ~80uA peaks (I think when RTC is counting), 11uA average.
The voltage levels are indistinguishable when RTC data is preserved or when it's not. I have noticed that powering on 3.3V when Vcoin is below a certain level it always loses RTC data and when above a level, RTC data remains intact.

CH1 - yellow - VnRF
CH2 - blue - Vcoin

Vcoin (blue line) was about 2.51V
The drop during current peaks is about 80 - 100mV.
This remains the same whetver the coin cell is full or even lower than 2.3V (when RTC data for sure is gone).

MATH measurement.
Measured the difference btw Vcoin (blue) and VnRF (yellow).
I don't see anything dramatic here to suggest that RTC has lost it's data.

Any ideas what else should I check ?
Maybe there are some firmware things we need to check to allow nRF to run down to 1.8V ?


texts:
When I open a project in Altium Designer 16, all text comments show as flipped 180 deg like so:

When I open the same project with Altium Viewer 09 all comments appear normal so I know it's definitely not the project.

I tried closing a project from Altium 16 without saving any changes and next time I open it there are already some unsaved changes to the project. This tells me Altium probably flips the comments on startup but then if I save the files and open them with the Viewer, all comments look normal.

Is there a setting to configure this or is it a bug?


texts: LED in NOT gate confusion: LED voltage drop vs transistor voltage drop

texts:
I saw a schematic for building a NOT gate, it worked, but there's something I don't understand.

Here is a pic of what I did (sorry about my finger hiding the push button)

If I push the button, the LED at the bottom gets turned off, even though there is a path between Resistor 2, the LED and ground (which is a bit strange to me).

I played around and realized that, if I put a resistor between the emitter terminal and the ground terminal, the NOT gate stops working, so I came to the conclusion that the path between Resistor 2, Collector, Emitter and ground, has less total resistance than if it had to go from Resistor 2 to the LED and ground.

My question:

I read that the transistor causes a drop of 0.7V, just like the LED, so why wouldn't the led shine even just a little ?

Thanks!


texts: sine, triangle and square wave generator?

texts: I have little experience regarding wave generating circuits. I am aware that there are various circuits that are able to create signals but i would like to know if there is a circuit that can output sinusoidal, square and triangle wave signals. Can you guys recommend one?


texts: STM32F0x1 comparator (COMP) and ADC on same pin simultaneously?

texts:
I am putting together a project that takes advantage of the comparator peripheral on the STM32F051 microcontroller. I have read in the documentation that for the comparator to work the input pin needs to be configured for analog... which is the same setup if you were using the pin as an ADC input.

Can I use a single pin, say PA1, as input and configure it as both a window comparator input and as an ADC input on ADC_IN1?

Are there any gotchas with this configuration such as additional noise that I should consider?

Datasheet (p 19)

Reference Manual (p 295)

An interesting reference, suggesting that this should be possible:

Taken from AN4232: Getting started with analog comparators for STM32F3 series


texts: Why is an infinitely large capacitor a DC open circuit?

texts:
This really sounds like a stupid question, but I believe it's worth asking:

  Due to \$I=C\frac{dU}{dt}\$, and \$C\$ is infinitely large, any minor
  change in \$U\$ would result in infinite current, which is obviously
  impossible. As a result, the voltage across the capacitor can never
  change, so it's always zero, and a voltage drop of zero further
  implies a short circuit, no matter in DC or AC.

Could any one tell me which step is wrong here?

I got it:

The higher the frequency of the signal, the easier it can pass.
The larger the capacitor, the easier the signal can pass.

When we say "a large capacitor is a DC open circuit", it actually means "After 5RC (time constant),  no DC signal can pass a capacitor, although it's very large."

Clarification:
In fact, 5RC only gets you to 99% of the steady state condition, rather than 100%. However, it's reasonable to simply consider it as 0 in practice, because it's too small to care.


texts: How damaging can a leaky microwave oven be?

texts:
This question is mainly about EMC and disruptive RF emissions.

I have noticed recently that each time we use our microwave oven the WiFi network becomes unusably slow (it is still working if you get close to the WiFi router).  When the microwave is turned off, the WiFi recovers and continues as normal.

I've been living with this annoyance for a few days, but now I notice that the WiFi router itself is now suffering from severely degraded WiFi output all the time.  I've tried changing channels, to no avail.

Previously there was a good WiFi signal everywhere in the house, but now I can only get a reliable signal if I'm standing a few feet from the router.  The router is about 8 feet away from the microwave oven and there is a wooden staircase between them.

Assuming the (900 Watt Panasonic brand) microwave is to blame for the original WiFi performance issue, could it also be possible that the leaked RF energy has physically damaged the WiFi router's transceiver circuitry?

More to the point, is my microwave dangerous to people in the house?


texts:
In the datasheet, the transistor has two max current values, in the case of the IRF510

Continuous Drain Current = 5.6A
Pulsed Drain Current a IDM = 20A

with a pulse width of 20uS

Which is the assumed  duty cycle for this values? Ts = 40uS and D = 50%?

Which current value should I consider if I want to work with a different duty cycle? 80% for example.


texts: Why does antenna length have to be at wavelength

texts:
Resonance occurs when capacitive and inductive reactances overcome each other. Thus is the familiar resonance frequency equation:

As the frequency gets lower, the antenna gets longer. But if this is only for making the antenna resonant with the selected frequency, why do we not simply add more capacitance (some metal balls or some conductor with volume) to the ends of a shorter wire to make it resonant with a low frequency instead of making it 6 meters long? Like this:


texts: I have to take 10 Push Buttons's inputs in my circuit with microcontroller being Atmega32. How can I take multiple push button input using 1 I/O Pin in the microcontroller. I came across CD4017 IC but it is a decoder and can only output.


texts:
I've asked several related questions, but I'm afraid that some of the answers that I received, while great answers, might be skewed because of incorrect assumptions or unclarity in my questions.

The answer to this question seems to indicate that any good conductor provides good shielding of both the E and H components of far-field EMR, because the fields are mutually dependent on one another for their existence.  The up votes would indicate a reliable answer. But answers that I've received to some of my questions have left me with doubts. So, I'll ask a different way:

Given a box that has continuous, conductive, metallic walls with no gaps, and air at its exterior and interior, when a plane wave hits the box from the outside, are the E and H fields attenuated equally?  Or, are there wall material properties that could cause EMR to emerge in the near field at the inner surface of the walls with E or H field dominant? For example, could a sealed enclosure provide good electric shielding and poor magnetic shielding of plane waves?  Specifically, is thicker or higher-permeability material required to shield the H component of a plane wave at 500 MHz than is required at 1 GHz?  Or, are considerations of thickness and permeability applicable only when shielding near-field AC magnetic fields or far-field EMR at frequencies below hundreds of kHz? Please assume that the box is sized such that all ingress radiation is in the near field.

Further, when I look at electromagnetic shielding equations and explanations thereof, I see no mention of field strength. A fairly well-known engineer assured me early on in my project that with attenuation in the neighborhood of 50 to 80 dB, field strength is not an issue, even under EMP conditions. Yet intuitively, I suspect that a pulse of 50 kV/m and 133 A/m would present unique challenges. So, how well will an enclosure whose walls contain less than 3 microns of metal with milliohmns of surface resistance stand up under an EMP? If your answer includes calculus equations, please include a brief explanation of the equations.


texts: How to calculate image brightness for use with LED panel

texts:
I am using a 64x64 RGB LED matrix for which I'm preparing some content.
The existing firmware reads RGB888 video files.

I'd like to analyse these files before uploading them, to make sure the overall brightness doesn't go past a threshold to keep the amperage in a happy zone.

So far I'm thinking about getting the maximum brightness based on the average brightness of each video frame.

My question is about calculating brightness in a way that makes sense in terms of electronics (which I'm not very experience with).

What is the best method to calculate the brightness of an RGB888 pixel in relation to amperage used by an RGB LED ?

There are multiple colour spaces that have a luminance channel (YUV,YCrCb,XYZ,Luv,L*a*b*,HLS,HSV), but do any of these make sense to use in terms of how much power an LED will pull ?

Would simply averaging R,G,B values be closer ?


texts: Is there any advantage to using multiple tracks in this PCB design?

texts:
I'm fairly new to PCB designing, but I'm loving experimenting with it. Currently, I'm trying to develop a simple PWM circuit using MOSFETs to control an RGBW strip, using an Arduino with an integrated voltage converter (design is based off this project I found). Here is a picture of my original PCB design:

To give an overview of the design: A barrel connector connects top right and supplies 12V and GND. This ground is then connected to the voltage converter, as well as to one of the legs of each of the MOSFETs and the GND for the Arduino to power it along with the 5V out from the converter. The Arduino will be powered from the 2 top pins on the left and then interface with the remaining pins on the left hand side, using PWM to drive the MOSFETs via a resistor. Finally, the RGBW strip attaches to the pins on the right.

Whilst I am confident with the functioning of the circuit, I had one question: Is it okay to connect all the GND pins of the MOSFETs in the way above? Or should they each have their own path like this design below?

As you can see, the only difference with this second design is that all the MOSFETs have a slightly different path to ground (with the exception of the white one). Will it make any difference which design I use? My main concern was that the top design would lead to voltage drop and that's why I have come to here, to find out whether it makes a significant difference or not.

P.S. I am using IRLZ44N MOSFETs and this voltage converter.


texts: Why Static Time Analyzer (STA) Engine doesn't show fmax for Fast Model?

texts:
I'm working on Intel FPGA. The Timing Analyzer (STA Engine) gives Fmax summary for both slow Models but none for the fast model WHY?. I didn't find any setting for this in documentation or in GUI.
(let me know if there is any!)

I suppose Timing Analyzer should give some value of Fmax for Fast Models as well.

BTW, Does Xilinx's Vivado let the designer know about feasible Fmax values for Slow/Fast Models in timing reports?

It's been a while using vivado, I remember it gives more importance to worst Negative Slack (WNS).


texts: Relay Contact Rating (DC Power) at different DC voltages

texts:
To note, I have Google searched this question for the last 2 hours with many contradicting answer and searched Stackexchange with no clear answer.

I need to determine if a relay with a Contact Rating of 10A 250VAC/30VDC can handle 25A at 12VDC and if it would be able to handle lower amperages at higher DC voltages.

A few websites suggest as long as the power does not exceed 300W, any voltage/ current combination is okay and other websites say that is incorrect.

Attached is the Relay Specifications for reference, however this is more of a general question about relays.

Thank you very much


texts:
I'm designing a small system in VHDL using the datapath and contorller method. Is it okay if I design registers that don't have a clock input (load data on the rising edge of the load signal) as they are being controlled by the control unit which is going to be running on the same clock signal; just to use less wiring.
Something like this:

PROCESS (load, reset)
BEGIN
    IF RISING_EDGE(load) THEN
        temp <= d_in;
    ELSIF RISING_EDGE(reset) THEN
        temp <= (OTHERS => '0');
    END IF;
END PROCESS;
d_out <= temp;

Is there anything wrong about the design above?
I want to make a shift register too; load on the rising edge of 'load' and shift on the rising edge of 'shift_right' input signal, wich would look something like this:

PROCESS (load, sh_r)
BEGIN
    IF RISING_EDGE(load) THEN
        reg <= d_in;
    ELSIF RISING_EDGE(sh_r) THEN
        reg <= reg (n-1) & reg (n-1 DOWNTO 1);
    END IF;
END PROCESS;
d_out <= reg;


texts: Logic level switch controlled via ground (0v)

texts:
simulate this circuit – Schematic created using CircuitLab
Hello, all.
My goal: to convert a ground signal pulse into a +5v signal pulse.
My question:  How on earth do I do this?
Backstory: My Jeep ZJ factory doorlocks operate using 5v logic.  My aftermarket alarm uses a pulsed (momentary) ground signal for both the lock and unlock feature (2 separate wires).  I'm attempting to use those ground pulses to mimic the function of the native door lock/unlock switch inside the vehicle.  The native circuit board inside the doorlock module uses a switched ground to "unlock" and a +5v is used to "lock" the doors.  I am attempting to get the aftermarket (2 switched ground wires) to communicate with the native circuit board (1 switched ground & one switched +5v).
The amperage is tiny because these signals drive relays on the circuit board.
Initially I was going to use a 7805 to switch/reduce a constant +12v signal to +5v.  I thought that I could use the momentary ground signal on the base of the 7805 so that it would only "turn on" and supply +5v when the ground/base was momentarily pulsed...which worked...but the problem is that when the system is idle (when +12v is on the input and the base is not grounded) there is +12v on the output terminal of the 7805.  Therefor this will not work because the output terminal MUST be at 0v when at rest...otherwise it would always be sending a lock signal.
Is there a logic level relay that completes a circuit ONLY when a ground is supplied to it?  If so, then I can use the +5v on the circuit board as a source and not have to reduce from 12v to 5v.
With an electro-mechanical relay this would be simple but these component level transistors are a little more difficult to grasp for me.
UPDATE:  I just wanted to say "Wow"!  I asked a question and within 15 minutes, 4 people jumped in and helped.  Thank you, everyone!  This place is great!


texts:
Can anyone tell me if the output voltage of a microphone (like the type on a webcam) is an AC voltage? And whatever it is, can it be measured on a standard voltmeter?

Thank you.


texts:
$$
R_s = 1k\Omega.
$$

http://i.stack.imgur.com/0iv6H.png

I don't understand why when the resistance is infinite $$v_1 = V_s$$.
It's clear that when a resistor has a very large value, the intensity is $$If = \frac{V}{ inf} = 0$$ and then $$I_s = I_1$$.

But in the second case (when the resistence f is 40kΩ) i don't know why the $$I_s=0$$ and $$v_1 = \frac{5}{6}vs$$


texts: Why do TQFP and TFQN have different advice regarding analog ground?

texts:
This question is in reference to How to split Analog and Digital GND planes for a TQFN device.

For the PSoC3, the advice on how to separate the analog and digital ground is different depending on the package.

For the TQFP, it is suggested that the analog and digital grounds have separate ground planes.

But for the TQFN package, it is recommended that the grounds are all connected to the same ground plane (the thermal pad).

Why are these two recommendations different? (especially since Henry Ott recommends against it).

Does it really matter?


texts: how to use sensored BLDC as stepper motor

texts:
I am making a huge line following robot and using arduino & sensor BLDC motor salvaged from Segway. The problem is that I am not able to control the motor properly. If the PWM signal is low the motor doesn't move, and if the PWM signal is slightly high then the motor goes at high speed. So I am not able to move the motor at slow speed which is giving problems.

Motor driver used: Kkmoon motor regulator

More info:

Motor phase wire connected properly with driver
Hall sensor wires not connected since it didn't make a difference in rotation when I was testing it.

Any solution to the above problem?


texts: Combining Left and Right Hook Speaker Wires Into One Speaker

texts: So I have an mp3 player, http://dx.com/p/94814, and the mp3 player comes with a left and right speaker output. For my equipment, I only have one speaker, not two. Can I just combine the left and right wires together and hook them up to the speaker? So left and right + together and left and right - together and just plug them into the speaker? If I do that, is there a possibility that I might blow up the speaker? For example, if both outputs output 10 watts each, does that mean 20 watts is going to the speaker and if the speaker only supports 10 watts it will blow?


texts: Three-phase transformer vs. three single-phase transformers

texts:
Some time ago a power plant here suffered a lightning strike which destroyed a transformer. A replacement was obtained from a decommissioned nuclear plant somewhere but required heroic efforts to move it to the plant. An employee there explained to me "The original equipment was banks of three single-phase transformers, but this one is a three-phase transformer. It's a lot bigger and heavier than anything they had to handle when they built the plant since it's basically 3 transformers in one box. That's why it's so hard to move it in."

Since then I've wondered what advantage there is to a single three-phase unit vs. three single-phase units suitably connected. Is there some subtlety in the design of the magnetic circuit which makes the heavier unit desirable?


texts: What is a typical duty cycle for Bluetooth headsets playing music?

texts:
When conducting SAR testing for Bluetooth headsets/earbuds, multiple tests are typically carried out using different types of modulation, all at a “worst case” i.e. duty cycle of 100%
What is a typical duty cycle when e.g. playing high quality aac encoded music or so, with both devices well within range. I am just looking for a ballpark figure.


texts: How long to wait between usage and charging of a LiPo (or Li-Ion)

texts:
Introduction

Like the most of us I've used Li-Ion batteries in many everyday devices. I also use a few LiPo Batteries in RC-airplanes. In the last years I read about their correct usage and charging. These are some of the things I learned:

Discharging a cell below minimum voltage kills it (capacity decreases).
Overcharging a cell above the maximum voltage kills it.
Thats why you use a balancer while loading a pack of cells in series. It balances the cells to an identical voltage level by discharging the higher-voltage-cells.
There's nearly no memory effect. No need to discharge before charging.
For long term storage charge it to 65-80%. Not less to avoid undercutting the minimum voltage. More voltage would mean more wear and ageing, because of a higher amount of chemical reactions.
You should wait some time after using a battery before charging it again. Which leads me to the

Question

How long should you wait after usage before charging?

For example if I use a battery powered string-trimmer or lawn-mower and the battery has gone empty (and probably quite warm) - how long should I wait before connecting it to the charger?

I guess reasons you should wait are temperature, or ongoing chemical reactions. Also I think you should wait longer if the battery had to deliver very high-current like the lawn-mower or a fast rc-airplane which will lead to higher battery temperature.

(Sidequestion: if it's about temperature would it help to put the battery in the fridge after use, to be able to charge it earlier?)


texts:
Before starting i'm a novice :)
I'm tring to count each time a 5v pump is powered on.
I build my sketch with a PC817.
The reading works but each time i put the ESP32 in deep sleep mode it triggered as false positive pump power on and it cycle.
I use the esp_sleep_enable_ext0_wakeup(GPIO_NUM_33,1); command to read the pump powered on.
Is anybody able to help me solving this issue ?
Thanks for your help !


texts: Learning Gates (AND, OR, NOT, NAND, NOR, ect) and just can't seem to grasp circuit diagrams

texts:
I am learning about gates, circuit diagrams etc. and I have been asked to create a 3 input NOR gate from NAND gates with 2 inputs.

Well, I know how to create a normal NOR gate with NAND gates, but I just ca'nt seem to grasp how I would get the 3rd input.

So the NOR with NANDS would be:

I didn't just look that up but I can't really draw my own, but I understand how that works, and I checked it with the truth tables and with some inputs.

How would I now create a similar circuit but for a 3 input NOR gate, I don't even know where to start.


texts: Measuring only AC Magnetic fields (40Hz - 130 Hz range) with an arduino and a Hall effect sensor

texts: How do I measure AC electromagnetic fields (the flux density) in microTesla (µT) whilst filtering out unwanted sources of non AC magnetic radiation such as the earth with an Arduino (any microcontroller really) ?.


texts: Is it possible to read the memory from a Holtek HT46R064B OTP(!) chip?

texts:
I am trying to get data from a Holtek HT46R064B. I know that the Chip is an OTP (One-Time Programmable) Chip. I ask myself if it is possible to read some parts of its memory.
In my case the chip is soldered to a PCB.
I am trying to prove that the device it is installed in has a planned obsolescence programmed in.
I found this datasheet where they say

"The Program Memory is the location where the user code or program is
stored. The device is supplied with One-Time Programmable, OTP, memory
where users can program their application code into the device. By
using the appropriate programming tools, OTP devices offer users the
flexibility to freely develop their applications which may be useful
during debug or for products requiring frequent upgrades or program
changes."

Is it even possible to read any data from this chip?


texts: Using a transistor as a switch between RX and TX

texts: I have a microcontroller(arduino) connected via its serial output(RX/TX) to a bluetooth module. i want to be able to program the microcontroller when the two are still connected but unless i disconnect controller RX the program will not upload. Question: is it possible to use a transistor to act as a switch between controller RX and bluetooth TX? my attempts have been unsuccessful so far...thanks.


texts:
I am slowly learning how to analyze circuits but I am wondering if my goals are unrealistic.  My main reason is to help me repair circuits boards that I come across in my line of work.  (I repair coin-op equipment)  Sometimes the most info I can find are schematics if I am lucky and they are usually lacking in details when it comes to voltages and scope readings.  I would like to be able to figure the voltages at any node and to understand what components could be bad if I get a lower voltage, zero voltage, higher voltage or supply voltage on any particular node.  Mostly DC voltages but AC signals would also be useful.  Most circuit analysis books teach from the point of view of engineering but my goal isn't so grand, I just want to do this for repair work.  Would this make enough of a difference to allow for short cuts and general rules that can allow you to work through a circuit and figure these voltages?.

Can people look at schematics, like the ones I have attached, and figure these voltages without a computer, or lots of time with a paper, pencil and calculator?  Can you mentally work out the voltages in a quick way?  I don't need exact, just close enough to see there is a problem.   If this can be done are there ways to learn this method?  It also seems most books break down parts of these schematics but I don't see too many that work their way through a complete schematic showing the thought process involved.  Is there a book or site that does this type of thing!


texts: Antenna transmission when a generic signal is applied

texts:
In a basic course of Electromagnetic Field, we arrived to introduce antennas. We studied the behaviour of the antenna by computing the electric field created when a sinusoidal input (the current flowing in a dipole) is applied to the dipole. I have a question: is this approach due to the fact that a generic signal (then, a generic current feeding the antenna) can be seen as a continuous sum of sinusoidal signals (Fourier Transform)? In this way, I should be able to apply superposition principle (at least in theory) for every sinusoidal component of the generic signal. And what about the electric field? I think it should be given (if my approach is correct) by the sum of an infinite number of plane waves, being each plane wave the effect of the corresponding sinusoidal component.

Can this principle (that is, to see a generic signal as the sum of sinusoidal signals, which should be always possible because phisical signals always have Fourier Transform) extended to other fields? For example, waveguides? As a consequence of my previous reasoning, when a video signal is applied to a coaxial cable, in the coaxial cable an infinite number of waves propagates: each wave should be the effect produced by a single sinusoidal component of the video signal.

Thank you!


texts:
I have a float switch that has three possible positions- open when above the water level, closed when below the water level, and rapidly opening and closing (freq~=0.1s) when its near the water level. I need to be able to distinguish bouncing around from the other two while only sampling the voltage across the switch every 1-2 seconds. I thought I could use an RC circuit to do this but my electronics background is fairly weak. I put together the following diagram:

simulate this circuit – Schematic created using CircuitLab

I think this circuit has a time constant of 1s which should roughly give me the average switch value over the last 1 second or so. I think the current should be 1mA, which I think is appropriate for reading on an Arduino. Should this work? Is it a good way of solving this problem?


texts: The most modern controller chips for a new active LIPO balancer design

texts:
I'm designing an active LIPO balancer for a hybrid power system that recharges from a gas generator, so it needs to be a lot different from a passive type balancer you'd have on a normal battery charger.  For starters, my battery pack (a 12Sx3.3volt battery built from A123 26650 cells - 39.6 total stack voltage) will never (not from the generator anyway) be allowed to charge above more than about 70 percent SOC, and never allowed to drain below about 40 percent SOC before the charging generator comes back on.

Obviously I need the ability to actively and precisely balance the voltages during heavy discharge and charging both, and I'll never get the opportunity to do a top or bottom balance like normal chargers do.  It's worth it to me to spend good money on the best and most efficient design I can do on this balancer so as to lower the fuel consumption of the generator engine.

My current design I'm drawing right now, is based on two chips from Linear Technology.  The first is the LTC 3300-1 balancer controller.  I'll need two of these to do a 12S stack of batteries.  The second chip is the LTC 6804-1 or-2 which is a battery voltage monitor that integrates with the LTC 3300-1.chip. This setup allows me to use tiny, low cost, off-the-shelf flyback transformers I can buy instead of having to make a custom transformer(s).

I will have connect my own micro-controller to this setup and provide my own software to control it, which will be written especially for the charging needs (staying between 40-70 percent SOC) of a series gas/hybrid charging system.  Charging above about 70 percent is too wasteful with gas.

How do I build a Li-Po balancer?
~~~~~~~~~

Meadows did not write the above question - the mods did, so nobody needs to answer.  It won't give me the information I needed anyway.

Please delete this entire thread since it now has no purpose to serve.  And delete my account too.  I have no use for a lame site where you cannot even ask if anyone else makes chips similar to what I'm already using, or if more recent chip designs are already on the market.

You took my already very specific and ON TOPIC question and turned it into something so generalized that there's no point in asking it.

If this was a car forum, people wouldn't be allowed to mention what kind of car they drive.  That's kinda stupid guys.


texts: Which IC can support LED debug of logical circuits?

texts:
I am new to electronics, and am playing with
some ICs (555, 74393, 74595 and logics like 7400) on
the breadboard.

To see what happens, I would like to put LEDs at various places
in the circuit. But I don't want to drain the circuit so that the
logics are altered. I believe I could use MOSFETs for the LEDs,
but that would use very much space, so I was hoping for a more compact
solution.

This would be one application, but what I really wonder is how to pick
the logical state (high/low) voltage of several nodes, and in a compact way,
draw more current from these than these nodes than they can provide.

After some googling I found the
74HC541 (Octal Buffers and Line Drivers With 3-State Outputs) and the
74HC9015 (nine wide Schmitt trigger buffer/line driver),
that look somewhat promising to me, to put between the circuit nodes
and the current consumers.

Are these suitable for that purpose, or are there other ICs
that would be better?


texts: How can two 5 V sources be connected to provide more current than a single can?

texts:
I am looking at this USB connector. It connects to two of your computer's USB ports in order to provide more current than a single port would be able to.

From what I have heard, connecting two power lines directly is not advised as a slight voltage difference between the two can cause a current to flow between them and lead to problems.

What kids of problems would a direct connection cause?

And what are some ways this problem is remedied?


texts:
Simulated on Multisim 14.0

In the above circuit, without RL the circuit behaves quite normally with a non inverting gain of 50 for any input at V1 till the output saturates to 15V.

Things however get weird when I connect a heavy load RL=75 ohms as shown.

For V1 = 10 to 25 mV the gain stays at 50 as expected. But as V1 is further increased, the gain starts to drop rapidly with a gain of about 35 at 50mV of V1 and about 19 at 100mV of V1. This drop however is not seen when I am driving loads of say 50 kohms; the gain stays constant. I am confused and cannot find any solution as to why this would happen.
What is the significance of connecting a heavy load and how does it impact the gain?

The op amp model used is a 741 with an open loop gain of 10k, open loop input impedance of 10 kohms and open loop output impedance of 100 ohms. Offset voltage was set to 0.

UPDATE: Okay tinkering with values in the dialog box led to some interesting results. Following jonk's comment about current compliance I went on to change the "Output Short Circuit Current" from 25 mA to 100 mA and it seemed to do the trick. Now even at 120 mV of V1 the gain seemed to stay at about 50.

So what is the deal with this "Output Short Circuit Current"? How does it limit the performance of my op amp? Help much appreciated!!


texts: Regular PWM vs Randomized Sigma-Delta (LED driver)

texts:
I came to a project where some LED lamps are being controlled with Randomized Sigma-Delta PDM. Each lamp has one MCU and about 100 cold white LEDs and more 100 warm white LEDs. The PCB is divided in the main part (with the first 10 LEDs, MCU and a few sensors) and the rest just dumb LEDs with current driver. The MCU uses 4 PDM outputs: 2 (cold light PDM + warm light PDM) used on the main part and the other 2 carried on to the rest of the board. I was wondering why not use simple PWM? Is that only due to EMI? If so, is it possible to estimate (magnitude at leas) how worse the EMI could be using normal PWM with constant pulse width within a cycle?

The way I see you cannot use too low frequencies with normal PWM because you probably see the flickering and also not to high frequencies to avoid high EMI. But I was wondering if you still can use normal PWM with good/similar results (so it's even much easier to verify the result with an o'scope later compared to random pulses, for example.).

Update:

Here's the reference for the datasheet explaining the Randomized Sigma Delta PDM:

XMC BCCU

and the Regular PWM is the normal PWM you usually find in MCU's which you only set the frequency and the duty cycle and you get a regular square wave.


texts: MOSFET differential amplifiers - difference between configurations

texts:
Consider the following differential amplifiers:

In the first picture, we have a basic differential amplifier configuration and we can assume that it's symmetrical (meaning M1=M2 and resistances are the same).

In the second one, we replaced the resistances with diode-connected PMOS transistors acting as active loads to the NMOS transistors. Since they're connected in diode mode, they enter saturation as soon as they conduct.

My question is, what are the advantages and disadvantages of these two configurations? The second one is obviously used in integrated circuit configurations, but when we observe them generally, how does the active load configuration act differently from the passive load configuration?


texts: Find 2nd order transfer function from step response

texts:
I have to find the tranfer function from the following step response. I would've known how to do this if the system had a steady state. Unfortunately, I don't even know how to begin this task.

I know, that the transfer function is going to look like:

Whereas ζ is going to be 0, as the Step Response does not have a steady state.


texts: Generate a 100 Hz Clock from a 50 MHz Clock in Verilog

texts: I have a DE0 board with a 50 Mhz clock that am I trying to to bring down to 100 Hz in Verilog. Could anyone help me with the code to do this?


texts: How can an intense solar storm harm the power grid?

texts:
I have read reports that an intense solar storm can cause Ground Induced Current to damage or disable the power grid.  This doesn't make sense to me.  The assumption seems to be that transmission lines have a neutral conductor that is earthed at each end, and thus, a potential difference in the earth at each end of the line will cause current to flow over the neutral conductor.  As far as I know though, transmission lines have no neutral conductor; only the 3 phases, which are isolated from earth ground.  As a result, if there is an earth potential difference between the two ends of the transmission line, it shouldn't matter.

Can anyone explain how this is supposed to work?


texts:
I picked up a bunch of Chinese-made 2S BMS / Balance boards.  As is the norm with inexpensive Chinese boards, they came with essentially NO documentation aside from how to hook the board to the batteries and load.

I've identified all of the devices on the board except for the chip that controls the BMS function.  This is a SOT23-6 with the letters "PAYG" on top.

I'm hoping that someone can identify this chip and point me towards a datasheet for same.


texts:
I've got a motor driver which can take 3A. But my motor seems to draw more than 3A as peak current when it's been turned on. And I would like to get rid of that since it blew up my motor driver a few times already by now. I do not have a oscilloscope and do not know how much the peak current exactly is. And I also don't have the type of the motor (Nothing is written at it at all). All I know is that it's an 18V motor with the TC4424AVP as motor driver connected like this.

I do not have the inputs of the TC4424 connected to a PWM signal sadly.


texts:
We're ordering some machinery from China and need it manufactured to Australian electrical standards including the wiring colour code. Unfortunately we don't have any electricians or engineers that work here (I'm an engineering student) and online all I've been able to find is info in forums - it seems government makes you purchase standards documentation. Some sources I've found indicated:

P1: Red
P2: White
P3: Dark Blue
Neutral: Black
Ground: Green

and others have indicated that it has since changed to:

P1: Brown
P2: Black
P3: Grey
Neutral: Light Blue
Ground: Green/Yellow

Can anyone with experience in this topic enlighten me on the current Australian standard before I request the spec for the machines.


texts: How do I hijack a reading from the circuit of my digital meter

texts: I have a tri - meter (ph, ppm, temp) that reads and displays readings on three LCD screens. I'm trying to hijack the measurement at some point in the circuit and read it in through on of the inputs on my Arduino. Can anyone tell me where I might start by looking at this circuit? The ph meter (left has only two wires) the ppm meter, apears to have 5, hot, return and three others. I'm assuming the signals are run through some sort of op amp, then displayed on the screens through on of the three logic chips.


texts: Braking Chopper necessary for BLDC controller?

texts: I'm developing a BLDC driver, which will provide up to 200W at a maximum of 7A. Now I'm not sure if i really need a braking chopper included, because the power is actually quite low, but ofc when a large load is spinned up to a large velocity, a big amount of energy will be stored. But when I now power the motor controller the whole time, for example with a velocity controller, the power will be used to reduce the stored energy without the need of a braking chopper, right? So my question is, when (for what application/control mode) is it really necessery to include a braking chopper and when can I just let the controller reverse power the motor to decelerate?


texts: source and channel encoding. can they be done together?

texts:
Why are source and channel encodings usually performed separately? Could they be made together?

thanks!


texts: Thermal resistance Junction - Maximum Power dissipation

texts:
I want to understand the real meaning of the parameter 'Thermal Resistance Junction to Air (°C/W) to calculate the power dissipation. So for example if the value of this parameter is 250°C/W, should I take this value as a constant if my ambient temperature is 50°C and then calculate my power dissipation with Pd= (Tj(max)-Ta)/R(°C/W)? Or I have to determine the Thermal Resistance Junction to air as a variable parameter and calculate it considering the ambient temperature and for my case with 50°C (Ambiant temperature).

I thank you for your help.


texts: Guitar Pedal not functioning at all, no sound created

texts:
Ok, so I'll do my best to explain my situation. (FYI, I am a beginner)

I'm building an overdrive pedal for a school project which I plan on modding with the help from a teacher. However, I thought I did all the steps correctly but when I plug it in, it just kills all the sound (no sound comes from the amp). Is it possibly a problem with my wiring or my circuit?

I'm attempting to follow the instructions for the pedal from this website:
http://www.instructables.com/id/Overdrive-Pedal/?ALLSTEPS

And here are some pictures of my project:

All help is appreciated and if someone thinks that they can help me and needs more pictures and details, please contact me. Thanks to you all!


texts: Making function using 2x4 decoder and one or gate

texts:
I frankly don't understand how to make it. I try to make but, I think it's wrong. How can I make it ?
Function is: $$f(a,b,c) = ∑(0,1,2,3,7)$$

My trying:

In addition using 3x8 I make:


texts:
I created a simple 8-3 encoder module (called encoder8to3) to replace a few repeated instances of Verilog code.  I then tried to use the module in levers2.v.  I get the following error when I run a Verilog test file:

  ERROR:HDLCompiler:69 - "C:/Documents and Settings/me/xilinx
  projects/wQCBG/levers2.v" Line 132:  is not declared.

I see all sorts of examples of how to create modules, but not many on how to use the ones that are created.  All I find are snippets of the use and not the declaration.

Will someone tell me how to properly declare encoder8to3 in levers2 please?

EDIT - codez, levers2, pared down.

module levers2(
     input [7:0] LL,
     input [7:0] RL,
    output reg [10:0] DIVISOR,
     output reg TD_ANY_MARK,
     output reg TD_NUMBERS,
     output reg TD_ONE_MARK,
     output reg TD_DONT_DISENGAGE,
    output reg FAULT
    );

(snip)

reg [7:0] x;

always @(LL, RL) begin
(snip)
        FAULT <= 0;
        /*
        encoder8to3(LL, x, FAULT);
(snip)

The encoder module itself is:

module encoder8to3(
    input [7:0] A,
    output reg [2:0] B,
    output reg F
    );

    always @(A) begin
        F <= 0;
        if (A[0]) B <= 0;
        else if (A[1]) B <= 1;
        else if (A[2]) B <= 2;
        else if (A[3]) B <= 3;
        else if (A[4]) B <= 4;
        else if (A[5]) B <= 5;
        else if (A[6]) B <= 6;
        else if (A[7]) B <= 7;
        else F <= 1;
    end

endmodule

I'm learning, and I'm just having some trouble with Verilog syntax.  So somehow, I need to tell levers2 (the first piece of code) where to find encoder8to3 or perhaps, like c, just warn the compiler that the module will eventually be used.


texts:
I’m building a device that requires 60+ serial distance sensors spread out a great distance, all communicating back to a central controller.
I could go with existing I2C distance sensors, but my options there are limited, expensive and (possibly) overkill for what I need.
To get data from 60 cheap IR distance sensors into an arduino or similar along a serial line, it seems I will need a microcontroller for each sensor to get its data onto the bus at the right time.
Is this right? Or is there a cheaper/better way to turn 60 dumb sensors into one smart sensor, without requiring 60 wires all coming back into one controller?


texts: How does a bare PCB product such as a Raspberry Pi pass ESD testing for CE mark?

texts:
I am designing a product that is to be sold as a bare PCB as a finished product, and so requires EMC testing to be able to CE mark. I am new to designing for ESD, and protecting every single exposed pin from an 8KV discharge seems overwhelming!
My question is how does something like a Raspberry Pi pass this test? Have they managed to design such that every pin survives 8KV, or am I missing something about how the EMC directive is applied?


texts: Need bin or hex file for Pic 16F648A Serial LCD

texts:
I have seen some kits and boards for a Serial LCD based on the PIC16F648A.
A have a few of the chips and a few LCDs. I'm not into PIC programming, does anyone have a link to the compiled software I can program my PIC chips with to make my own serial LCD?


texts:
I am attempting to replace a wall plug power supply with a supercapacitor. From analysing the behaviour of the wall plug I can see that the current drawn is .25A with 800ms spikes of 1.5A (as determined by an arduino board).

However when I try to use the supercapacitor (15F, 7VDC), the voltage appears fine, but not enough current is being drawn. The highest current I have seen drawn on the multimeter is .11A, so the system in question does not work.

I think this may be down to the internal resistance of the supercapacitor. So the next step I will try is to increase the number of supercapacitors and place them in parallel, thereby decreasing the resistance.

However as supercapacitors are advertised to be capable  of charging in a matter of seconds, surely this means they can handle a high current (at least 1.5A anyway). Or will supercapacitors draw more current during charging than they would be capable of supplying during discharge?

Any help here is greatly appreciated.


texts: Equivalent voltage rating of Parallel connection of capacitors with different voltage rating?

texts:
What will be the equivalent voltage rating of two capacitors of different voltage rating connecting in parallel ?

And how does it differ in the series connection of two capacitors with two different voltage ratings?


texts:
I am trying to find a substitute for a terminal block like this:
Are there any connectors which come with wires already crimped in, but can be used with the male version of the above terminal block.
This is the male version:

Its just that I have a lot of terminal blocks in my unit and I have too many wires to screw into the terminal block and some of them come out by wiggling the wire. It would be really helpful if I can find a connector with ribbon cable which can be used with the male connector.


texts: PH differential instrumentation amplifier

texts:
I have a computer engineering background with minimal experience with real EE work. I want to interface to a ph probe and was wondering what the best way to do this is.

It seems to me there are 2 basic options for doing this. The first is fully differential, where the ph probe connects to Vin in the diagram below. The output can then be read from the output of the first 2 stages via differential ADC. Is this correct?? Are there any flaws with connecting a ph probe directly to this circuit??

Second stage can be excluded and is just if you want a single ended signal ended with additional gain

This second design is simply a single ended gain+offset configuration. First stage does some gain, second stage offsets and has a bit more gain.

Which one is ideal for minimizing signal loss/noise? My thought would be that the first circuit would be better at noise rejection since it is differential, and feeding this into a differential ADC, some common mode noise would be rejected.

Are there better configurations for doing this?? I am interested in reading range of 3-10ph only. In this case, is one better than the other?

Some notes on ph probe:

Extremely high impedence opamps are required(eg femptaamp input bias
current).
-420mv is 0ph, 420mv is 14 ph(may have that switched around).


texts: How should batteries for an APC SmartUPS SURTA 2000XL be connected?

texts:
TL;DR How should a set of 4 lead acid batteries (12 V, 9AH) be connected for an APC SmartUPS model SURTA 2000 XL?
This afternoon I set about to replace the batteries on our server room UPS, a job I have done before. We ordered the same batteries we have ordered before (last time was about 2-3 years ago). I removed the battery cartridge & opened it, then I methodically replaced each battery in turn - first removing the old one and replacing it with a new one, taking care to connect it the same way (or so I thought).
Unfortunately, when I connected the battery cartridge to the unit, it immediately shut down. After scrambling to restart the servers which had just been unceremoniously powered off, I removed the cartridge again and double-checked the connections, making sure each was firmly connected, and reconnected the cartridge. This time, the UPS came on (without pressing the power button), but it only stayed on for 3-4 seconds before shutting down briefly and coming on again, and cycling through these state (on for 3-4 seconds, shutting off, then coming on again for 3-4 seconds).
The obvious conclusion is that I connected the batteries incorrectly, but I was very careful to copy the configuration I found. And if that's the case, I must admit I'm at a loss as to how to connect them correctly.
Here's a quick sketch of the way the batteries were connected:

The connection to the UPS is in the upper-right hand corner. The batteries were connected red to red and black to black, except for one white connector between the black terminal on battery 2 and the red terminal on battery 1. This struck me as odd when I first opened the cartridge, but I went ahead & copied the configuration I found.
I'll admit that my understanding of batteries & electricity is limited. I've searched for a diagram of the correct battery configuration, but I can't find one (or perhaps I'm not searching for the correct terms).
Is this arrangement of batteries correct? And if it's not correct, how should they be connected?


texts: How to calculate the voltage in this open circuit?

texts: I can't understand how to calculate the voltage between a and b in this open circuit. Resistances like the 9 Ohms and 13 Ohms can be ignored since no current is passing through (In case we connect a Voltmeter, we consider infinite resistance). But, how can I analise or simplify the other circuits?


texts:
I'm trying to source parts to build my own Huzzah32 (ESP-WROOM32 Dev board) and have grabbed the BOM from Eagle:
BOM:

I've found certain parts that are more 'unique' to me, at least, such as the USB-UART Bridge CP2104. But I want to be sure I'm getting the right capacitors, resistors etc. I have a general understanding of how these SMD components work but want to do my research to ensure I'm in good shape.
When searching on Mouser I see a wide range of 10uF ceramic caps in the 0805 package with different voltage ratings, etc. I know that just about everything on the Huzzah and ESP chip is 3.3v, but don't see caps specifically rated for 3.3v? I'm sure there's a general discipline on what parts to use, and was hoping someone had some wisdom to impart on it.


texts: OpAmp I/O range determination from a datasheet

texts:
I found a similar question here and understood the following: input signal must be within the input common-mode voltage range of the OpAmp. Take for example AD8055 which can be powered by dual or single voltage supply. The specsheet describes IO characteristics for only dual power supply:

TA = 25°C, VS = ±5 V, RF = 402 Ω, RL = 100 Ω, Gain = +2, unless otherwise noted.

However, I wish to power this OpAmp with a single power supply. Let's say I will provide -Vs=0V and +Vs=5V. How do I determine IO characteristics than?

Here's another example: LT1818 OpAmp. They actually provide IO characteristics for dual and single power supplies:

TA = 25°C. (Note 9) VS = ±5V, VCM = 0V, unless otherwise noted

TA = 25°C. (Note 9) VS = 5V, 0V; VCM = 2.5V, RL to 2.5V unless otherwise noted

Now they introduced positive/negative notion for IO voltage. How to understand it? Is it the maximum/minimum voltages, voltages that used for Vin+ and Vin- respectively, or they omit the '-' sign for the negative voltages? It does implicitly say that on a single 5V supply, the output swings from 1V to 4V with a 100Ω load connected to 2.5V.

My video signal will will range +0.5V to +2.5V. I want to use any of these two OpAmps as buffers G=+1. I know that if I use dual +-5V power supply, they will work. However, I wish to stick to single +5V supply. Would any of them still do the buffer job for my video signal range?


texts:
I’m trying to implement 8 bit ADC in FPGA. FPGA running at 100MHz clock.
PWM signal is given to RC filter. Knowing that f=1/2piRC,
I have trouble with choosing the component's value. Is there any rule to
find RC values and frequency?

I chose 100Mhz frequency, 7Kohm resistor and 10nF capacitor. I didn’t‘t get expected output. I used LVDS buffer of FPGA as comparator. Considering the LVDS behavior,
How to find resistor value?


texts: How to find voltage on zener diode while there is a current source

texts:
simulate this circuit – Schematic created using CircuitLab

I'm confused about whether zener is on or off due to not being able to know voltage on V0. I tried to find by applying KCL & KVL, but current on the diode (Id) and the resistor (Ir) is not equal to each other. I'm using the shockley diode equation.(Id=Is(e^(Vd/Vt))). This current source being connected to zener diode instead of a voltage source makes something complicated.
Which way should I follow to find V0?
Hope one can give me a trick.

Thanks in advance.


texts: Is it a good idea to refresh a display (8x8 LED matrix in this case) inside an interrupt handler?

texts:
Let's say I have an Arduino connected to a 8x8 LED matrix.

In my case, the LED matrix is driven using two 74HC595 shift registers (one for the rows and one for the columns).

Since it can only set the status of 8 LEDs at a time (one row), idea is to refresh the rows fast enough so that the human eye will not notice the blinking.

This is usually done in the loop() method :

int led_status[8]; //contains LED status (which is on/off) for each row

void loop() {
   process_otherstuff(); //eg: key inputs,...
   display(); //shift led_status[] to shift register and latch result.
}

Here is potential issue : what if CPU has to do some time consuming process in the loop method (eg: heavy math) ? The display() method will be called with some delay which might be noticeable (led will start blinking or even worse : stop refreshed, appears to be stuck on one row).

A possible solution I can think of is the refresh the LED matrix in an interrupt handler :

void setup()
{
  analogWrite(3, 100);
  attachInterrupt(1, refreshdisplay, RISING);
}

int row = 0;
void refreshdisplay()
{
   //refresh one single row
   refreshrow(row++);
   if(row > 7) row = 0;
}

Is this a good idea ? That way, no matter how much time is spend in loop() method, display will be refreshed as fast as needed.
Potential issue I can see is a lot of time is now spent in the interrupt, which is usually a bad thing (interrupts handler should be as short as possible).

Another solution is to use a separate LED controller driver (eg : connected to Arduino using I2C bus) but this require changing components list.


texts: Can I use 2 CR2032 batteries to power an EL light strip normally powered by 2 AA batteries?

texts:
I am trying to get one light strand to function with a different battery by cutting off the batteries from the light strands then switching the battery controllers and soldering the new battery controllers to the other light strands.  Here is a picture of the light strands lit up normally.

Specifically I am trying to get a light strand from blue El wire (uses 2 AA batteries on its black controller) to work with the batteries from a different green light strand (this one uses 2 CR2032 batteries in its white controller, see picture of unlit green light strand with exposed CR2032 batteries)
.

I don't care how long the new battery controller/El wire lasts, I just need it to light up for about an hourish.  So far I cut off the black battery controller to the El wire, and soldered it to the new white controller with the CR2032 batteries but it does not function. See picture:

Then to test my soldering and polarity of wires I soldered the other cut off green light strand to the cut wires from the blue El wire with the AA black battery controller and it worked.

OVER ALL QUESTION: So is there anything I can do to make the blue EL wire light strand work with the smaller CR2032 white battery controller from the other green light strand?

FYI Here are some links to the products I am talking about on amazon if you have further questions:

This is the exact El wire product:
https://www.amazon.com/gp/product/B00BUIN3XW/ref=oh_aui_detailpage_o09_s00?ie=UTF8&psc=1

I want to attach this light to another similar light that uses 2 CR2032 batteries.

Here is the link to the controller:

https://www.amazon.com/gp/product/B06XN5R88X/ref=oh_aui_detailpage_o09_s01?ie=UTF8&psc=1