texts: What is this sideways capital I component with an x in the middle on a schematic for an Intel chipset?

texts:
Here is the schematic

The compoent in blue -- it appears to vaguely resemble a 0 ohm resistor. Is it a TVS diode?


texts: 555 timer - Creating a 5 second astable pulse

texts: I need to a clock pulse where each pulse last 5 seconds for a traffic light controlling system assignment. I haven't worked with the 555 timer much and I haven't had any success with this. I used the equation t = 0.7*(R1 + 2R2)*C and tried designing a circuit with a 470uF cap, 1K r1 and 7K R2, but this only gives me a signal of around 4 seconds. Why is this? And how could I fix this?


texts: How can I design a circuit that will turn on when a wire is cut?

texts:
I'm trying to build my own cable lock alarm (for science!) and am having trouble figuring out a way to detect that a wire has been cut.

The circuit has to

Use no power at idle (or at least, very very little so that the batteries don't have to be changed every hour)
Sound a speaker when a specific wire is cut

My knowledge of electronics is minimal.. I know what capacitors, diodes, resistors and other basic stuff are and do, but I don't have a good grasp on how electricity flows in anything other than a single loop.

I seem to remember once making a circuit that was something like this.. (and oh geez, I don't even know how to do a proper diagram so forgive me folks)

/----------[battery]-------\
|                          |
|--------[light bulb]------|
|                          |
\-----[wire to be cut]-----/

And the bulb would only light up if the wire below was cut, because electricity always takes the path of least resistance.

Anyway, this is going to be a battery operated circuit and I'm pretty sure that diagram up there is a short. I think there was a resistor involved but I don't remember where it went.

If anyone can give me some pointers that'd be great!


texts: Servo motor misbehaves e.g. jumps and glitches

texts:
I am controlling a digital metal geared servo motor (MKS-HBL880) using TI's C2000 LaunchPadXL TMS320F28379D microcontroller. The servo is powered with a 7.4V 2S-Lipo battery. The microcontroller and the external battery are common grounded. When the battery is fully charged, the supplied voltage is 8.3V.

The problem is that sometimes the servo motor acts erratically, e.g. jumps between positions and gets stuck during operation. Currently, there's a 1000uF capacitor between the V+ and GND pins. (The datasheet is here.). Using this capacitor reduced the jumps and misbehavior of the motor, but did not fully solve it.

As Tony Stewart suggested on a different question of mine, the capacitor should be ultra-low ESR. So I decided to order a number of low ESR capacitors with capacitance ranging from 22uF and 1200uF and test which one solves the issue. I found the following options. The full datasheet can be found here.

Can someone clarify if the highlighted capacitors would do the job, is the ESR low enough, and if I am on the right path?

Thank you.

---- EDIT ----

Voltage across +V and GND pins of the motor:

https://youtu.be/vTABHKIUKqs

Voltage across 10 Ohm resistor in series with +V pin of the motor:

https://youtu.be/gONaPpY2UEg

Note that this result is largely influenced by the choice of \$\Delta t\$.

I introduced a series resistor to the decoupling capacitor, creating a RC circuit and the spikes/dips in the supplied voltage disappeared.

Video: https://youtu.be/1aO6T7MvkCk


texts:
Short version (can provide more information if wanted) we have a display (TFT with TTL driver) that we control via PIC32 and Epson Display IC. The supplier changed their driver which should have been a drop in replacement, through some troubleshooting and testing we found the reason it did not work on our system was a capacitor we have on the clock line going from our driver to theirs.

Unfortunately there aren't any notes as to why that capacitor is there, my assumption is noise mitigation, or emissions mitigation.

Layout is Clock out -> 27 ohm resistor -> 27 ohm resistor and a 100 pF cap connected between them to ground:

Taking measurements the only difference that I could see was the voltage was a little lower with the capacitor there.
With capacitor:

Without capacitor:

I'm guessing the new display is just more sensitive to voltages on the clock, so I'm not too worried about that being the reason it works. I'm just not sure aside from emissions testing how I can confirm that capacitor is for noise mitigation rather than emissions.

Thoughts?


texts: What does this Op Amp circuit do in this circuit for a line following robot?

texts: I have seen a schematic for a line following robot, but there is something that I can't understand and is shown in the figure below, what is the purpose of the Op Amp circuit? I know that BREAK input in H-Bridge is independent on other pin. Could some one explain what this circuit does?


texts: Calculate Resistor Value for Optocoupler - 24VDC Anode

texts:
I'm looking for help and unfortunately stuck for time on a project, so hoping someone wouldn't mind helping me out.

I am trying to calculate the resistor value required for an opto-isolator circuit. I am powering a 24DC magnetic reed switch passing ground through a Siemens SFH615A:

http://docs-europe.electrocomponents.com/webdocs/009c/0900766b8009c194.pdf

Can someone recommend a resistor value, thank you very much.

I have used the calculator available here: http://led.linear1.org/1led.wiz
with a 24V supply, 1.5 forward voltage and 60mA forward current.

I would be grateful if someone could double check


texts:
I have an Horiba gas analyzer having the analog out linear 0-1. My data logger (10 bit) has the input 0-10V. Of course, I can use like that but on higher ranges for analyzer gases the reading after A/D conversion is not accurate.
Can you give me an linear voltage amplifier circuit drawing from 0-1V to 0-10V? I have some practice in electronics and I think I can do it by myself. The circuit can be for one channel.
Thank you,
 Tiberiu


texts: Parts is in red boxes. This is from a Chinese android TV box and I am searching for a replacement part. I searched around and it might be an a shielded SMD power inductor but not sure what to replace it with. I don't see any exposed coils on the side and I see 2 copper ends soldered on the board and no pins underneath it.


texts:
Title says it: I'm working on building a high current USB charger for my devices so that I can integrate USB ports into my headboard. However, I'm having a few glitches.

When I plug in a device, the voltage drops ~0.5V. Each device after drops it ~0.1V further per device. I have it up to 5.5V at the moment, and plugging in my devices will drop it to 5V. Yet it's charging my tablet just fine. Very fast actually even without declaring the current capability.
My iPhone will not charge through this. I have a MAX14667 chip I am integrating, but was hoping I could get it to charge without it for testing purposes as they are small chips and pain in the butt to work with. Is this because I haven't declared the current capability with a resistor divider yet? The most I got is a "not supported" message from the iPhone.
For the purpose of easy testing, I'm using a TI LMZ23605 module. However, for some strange reason the resistor values calculated by the TI site are not giving me 5V on either of the two modules I have prepped for a breadboard. Here is the schematic:

So my values are Rfbb = 1K, Rfbt = 5.6K + 352. This has given me 5.5V. Plugged in my tablet, dropped to 5V.


texts: Protection against audio output shorting

texts: I built a little USB powered audio amp (op-amp based) with 3.5mm audio jacks as an output. If I plug something to the audio jack, then during plugin moment there is a small period where the amp output is shorted. This causes my USB connected micro-controller part to reboot. What would be the most elegant counter-measure against that?


texts: How to keep a small Li-Ion battery on float for backup service?

texts:
I have a number of small electronic widgets (similar to small arduino boards) that generally draw 100uA-10mA avg with infrequent 50mA-100mA peaks (e.g. radio or cellular TX) and for some I'd like to power them from mains with battery backup. The issue I'm facing is that LiPo or Li-Ion cells left fully charged (4.2V) have a very short lifespan (I've had some die in a couple of months). As far as I can tell, the solution is to charge to 4.1V at most, possibly even less. This reduces the capacity but that's an OK trade-off if it allows the battery to last for several years.

So long for the theory, where I'm stuck is in turning this into a cost-effective practice. The widgets typ cost under $10 and are typ 3/4"x2" in size, so I'm looking for something cheap and small. As far as I can tell, a programmable LiPo charge management IC is not in the cards. (They also tend to come in QFN/DFN packages that are very difficult to hand-assemble.)

I've found a number of simple charge ICs that can be configured for 4.1V charge, but they are either not available in small qty, or only in DFN packages, or require several external components (such as a mosfet), or cost >$2.

I've looked at LiFePO4 because it's supposedly less sensitive to remaining fully charged, but I'm not finding attractive small batteries (the AAA Soshine 280mAh is about the only game in town) and the charging ICs are relatively pricey too.

The best I can come up with so far is the MCP73831-2AT. It costs less than a buck and comes in SOT-23, which is easy to deal with. What makes it interesting is that while it charges to 4.2V the "-2AT" version terminates the charge when the charge current reaches 20% of the max configured charge current. So, for example, I'm using a small 240mAh LiPO, configure the max charge current to 200mA (0.83C) for longevity, then I end up with a charge cut-off at 40mA, which is C/5, which means the LiPO gets charged to approx 85% capacity, which apparently is about the same as charging to 4.1V.

For solar charging applications the CN3065 chip looks attractive in that it has a end-of-charge at 10% of max current. That should charge the LiPO to about 92% of max capacity. A bit more than the MCP above, but perhaps OK.

My question is whether there's a simple alternative I'm overlooking.

There are other questions related to mine but they don't really address my use-case. Specifically:

Charging and Using a Li-Po battery simultaneously
How to power a widget, while the li-ion battery is charging?
Providing DC power with failover DIY for IP camera
What are the problems with LiFePo4 float charging? How should I charge them?

I got tipped off to using the charge-cut-off current setting instead of focusing on the charge voltage by http://www.powerelectronics.com/mobile/proper-care-extends-li-ion-battery-life, which states "[...] ending a charge cycle when the current drops to C/5 is similar to reducing the float voltage to 4.1 V. In both instances, the battery is only charged to approximately 85% of capacity, which is an important factor in battery life.


texts: Character (HD44780 based) LCD backlight is always on

texts:
I have a Solomon LM1112SYL 4x16 LCD. The display has 16 pins and the datasheet (http://www.allelectronics.com/mas_assets/spec/LCD-108.pdf) shows that pins 15 & 16 are for the backlight power supply. When I power up the LCD without having any connections made to pins 15 & 16, the backlight is on. I would like to have the ability to dim or power off the backlight.

 NOTE: clabacchio has another post about this module at LCD Module Datasheet Or Other Info.

I see that on the back of the module it is has a block silk-screened on it which appears to be for the backlight.

    VDD/VSS JI,KI
    15K/16A JK
    15A/16K JA

I believe what this information is telling me is that JI is VDD and KI is VSS. If JK pads are shorted to the pads then pin 15 will be the cathode and pin 16 will be the anode to the backlight LEDs. If JA pads are shorted to the pads then pin 15 will be the anode and pin 16 will be the cathode to the backlight LEDs.

I have not followed the traces yet to confirm this. Does anyone know if my assumption is correct? I have not it tried yet as I don't want to ruin anything but I may give it a go once I trace the connections and make certain there will be no ill affects.

Update

Thanks Fido UK, for pointing out what should have been obvious but escaped me for a time. For some reason I was thinking that there was a via or something where those blobs of solder were. I took my solder wick out and unsoldered the blobs and found jumper pads underneath. Works great now.


texts: Why is the STM32 reference manual stating the wrong sample frequency for I2S?

texts:
This could be a misunderstanding but everything I have gathered and seen it looks like there's a disconnection on what the reference manual says.
On Pg. 2212, in the STM32H753ZI it states:

"The master clock rate is fixed to 256 x FWS, where FWS is the audio sampling frequency."

So according to STM32 the FWS is the audio sampling frequency.
On page 2225, an equation sheet is presented to the end user to show how to acquire the desired sampling frequency (FWS) based on the SPI kernel clock.

On page 2226, a table is shown for a cheat sheet to configure the registers to get the correct FWS frequency.
The settings I used are highlighted.

Then in practice this is what I have obtained.
The green signal is when the samples takes place. High is the half complete DMA trigger and theow is the complete DMA trigger. The buffer is 4 length long of uint16_t
The yellow signal is the FWS signal. As you can see it Is shown to be at 48kHz stated above in the table. However when calculating the sampling frequency of the green it's ~96kHz. The math below.
It takes 20.8uS to trigger at 2 samples according to the green signal, then in 1 second you will have 96ksamples.
I have tried using the FWS= 96Khz configuration and it gave me a sampling frequency of 192kHz using the same logic above. I am seeing a trend where the sampling audio frequency is actually FWS*2.
Can someone shine some light onto this to see if the logic is wrong or if is this actually correct?

CODE:
uint16_t RxBuff[4];
uint16_t TxBuff[4];
uint8_t TC_Callback = 0;
uint8_t HC_Callback = 0;
char uartBuff[8];
void DMA1_Stream0_IRQHandler(void) {
    if (((DMA1 -> LISR) & (DMA_LISR_TCIF0)) != 0){
        DMA1 -> LIFCR |= DMA_LIFCR_CTCIF0;
        TC_Callback = 1;
    }
    else if (((DMA1 -> LISR) & (DMA_LISR_HTIF0)) != 0){
         DMA1 -> LIFCR |= DMA_LIFCR_CHTIF0;
         HC_Callback = 1;
    }

}

int main(void) {
    init_Clock();
    init_I2S();
    init_Debugging();
    init_Interrupt();
    init_SpeedTest();
  while (1)
  {

      if (HC_Callback == 1){
          GPIOA->BSRR |= GPIO_BSRR_BS3_HIGH;
          HC_Callback = 0;
      } else  if (TC_Callback == 1){

          GPIOA->BSRR |= GPIO_BSRR_BR3_LOW;
          TC_Callback = 0;
      }

  }
}

UPDATE 1:
Changed the FWS = 96kHz based on the tables, ten changed the RxBuffer length to 2. Here was the result. So essentially the DMA triggers based on every 1 sample.
Even though it says 96kHz I am doubting it is. If every 2 sample triggers at 92kHz and every 1 sample triggers at 196kHz the sampling frequency is ~ around 192kHz. All this is saying 2 samples per / 10.51uS = 192kSamples/ 1 second


texts:
By rubbing a cotton cloth along a PVC pole, static electricity is generated. How can this be used to charge a capacitor?

http://home.earthlink.net/~lenyr/stat-gen.htm is what I'd like to do, but it doesn't explain how it should be wired up.


texts: Why does the voltage across the speaker oscillate in this circuit?

texts:
For my final exam, I decided to work on this circuit design available online. Sorry, I forgot the website. No credit is due to me.

When I simulated this over at MultiSim 11, the voltage across the speaker oscillates when the switch is in its OPEN state. I don't know why. I haven't dealt with speakers before, just RLC, diodes, and BJT components.

As a side question, is it possible to use Laplace transforms on BJTs? If yes, can someone point me to a good reference on how to do it?

Speaker resistance is at 8 Ohms.

This is the simulation result. Red means Vin. Vout is the orange.


texts:
Andy aka, rioraxe and Daniel thank you very much for taking the time to respond to my first question.

In the schematic below, an A/C voltage is induced in the inductor. The MOSFET is used to control the voltage to the load.

1) What would be the best way to handle the resulting freewheel current when the MOSFET is switched off? And as was said in answer to my first question, I would like to be able to reuse the energy that is stored in the inductor.

2) How could I get the flyback current to die down very quickly? This would be way more important to me than being able to reuse the stored energy.

<

simulate this circuit – Schematic created using CircuitLab


texts: What is causing this distortion on a 20MHz control signal?

texts:
I'm having an issue with a PCB on which I have a microcontroller and an external SRAM. I don't want to fully describe the problem as I already posted a question regarding that. Link

Since that I found out that maybe there are PCB design issues which could cause the symptoms. Here comes my question which I think it worth to ask separately.

What can cause the distortion visible on the picture?

Ideally, the signal should be a square wave with exactly 50ns 0V and ~50ns 3.3V

Oscilloscope settings:

Volts/DIV: 2
Time axis: 50ns/DIV
Attenuation:10x
Probe connected to OE pin of the SRAM (farthest point from the driver)
Probe ground connected far away to the shielding of a connector

Another picture:

Oscilloscope settings:

Same as above, except the probe ground is connected directly to the SRAM's GND pin.

About the board:

Power: 3.3v
No impedance matching between the chips
Trace length:43.215mm

I would not say that 20MHz is high frequency, that's why I didn't care about impedance and termination. Could you please confirm this in addition to your opinion on the signal?

As per rdtsc's request in a comment, I checked a 25MHz oscillator on the same board with the same oscilloscope settings as above. This is how it looks like:


texts: Controlling IRF540N with MCU for LED on/off switching

texts:
Note: Schematic is not my best work, but this should pass on information.
I've designed the following circuit; The purpose of this is to have the Arduino Nano control the WS2811 LEDs and also control their power via MOSFET IRF540N.
Problem is: When I ground the MOSFET Gate pin to 0V, the LED's still glow, meaning that there is still a flow going on. I've grounded manually via wire.
Only when I remove the connection from MCU pin D4 and WS2811 pin DI will the LED's go out like intended. So my conclusion is that the MCU pin D4 is Weakley conducting to ground(?).
The only advice that I've gotten is to use a P-Channel MOSFET instead of N-channel. I don't know what options I have at the moment. Would adding a diode in between the MCU and LED help here?


texts:
What actual protocols exist out there that employ Offset Quadrature Phase-Shift Keying (OQPSK)?

What do they use for the frame synchronization marker (or "preamble" or "sync word" or "flag")?

Do they use a unique word, a unique pattern of bits?  If yes, do they do some kinda bogus bit insertion (similar to the zero-insertion what the old SDLC protocol did)?  If not, how can they guarantee that the data never mimics the frame sync marker and a spurious frame sync occurs?

What do they do for Offset QPSK to synchronize the I/Q phase of the intermediate frequency (IF) signal?  Does the frame sync marker give the receiver an unambiguous signal from which to derive the correct I/Q reference phase?

Lotsa questions.  I've been thinking of OQPSK a bit and have rambled out loud about it at the DSP Stack Exchange.  OQPSK naturally pairs the bits from a single serial stream into "dibits".  The even and odd bits naturally are routed to the I and Q signals without any contrived pairing of bits.  Then it seems to me that the 16 bits 0011001100110011 would be the natural marker for the lowest instantaneous frequency and 0110011001100110 would be the highest frequency.  One pattern could be the frame start marker and the other pattern a channel idle marker.

But then the 15 bits 011001100110011 should never occur in the data and a bogus 0 should be inserted after the 14 bits 01100110011001 so that neither marker would ever appear in the data.  In the style of SDLC, the receiver would always remove that bogus 0 that occurs after 01100110011001.  If, before the zero-removal, a 1 appears after 01100110011001, then I think either a channel idle or frame start marker is occurring (one more bit is needed on one side or the other of the 15 bits 011001100110011 to know for sure).

But this paper suggests other bit patterns (Barker sequences) for markers.

What are the protocols in use?  What is the wisdom of those here that have actually worked on OQPSK at a low level?


texts: Communication Technique used in Commercial Vehicle Tracking Systems

texts:
I am working on a vehicle tracking system that conveys the coordinates information from the vehicle to a server via GPRS communication. For this purpose I am using a GSM module with an arduino uno.
As I was working on this I wondered as to which technique is used in commercial vehicle tracking systems.
Which communication methodology is used in commercial vehicle tracking systems? (Is it GPRS, WCDMA or something else?


texts: Does the letter k in electromagnetics represent wavenumber inside a cosine?

texts:
I am having a intellectual debate with a colleague on whether k (in this equation below) represents the wavenumber k (that is used in electromagnetics) or does k in this question not refer to wavenumber k and is k just some letter? My understanding of this question is that t is time, z is space, and k is wavenumber.

The question states:
The magnetic field of a wave in free space and in cylindrical coordinates is given by

where t is in seconds, and r and z are in meters.
(a) Determine k.
(b) Assume k = 1 (rad/m). Consider a square contour C in the y = 0 plane as shown in the following figure. Find the line integral of the electric field along C in the direction shown


texts: Servo jitters at specific positions, why?

texts:
I have a Pololu Micro Maestro, and it's great.
But when i tell the servos to move to specific positions, sometimes it makes a beeping-like noise. This only happens at specific positions. It's not because I'm trying to make it go farther than it can, it also happens when it is positioned around the middle.

This happens when I use a laptop to control the servos via an application written in .NET

I have only tried controlling them either via my own application or the maestro control panel.

Is there any way to avoid this?

I hope you guys understand what I mean.
Thanks


texts: How do I select base resistor values for low duty cycle (<5%) astable multivibrator?

texts: I am designing an astable multivibrator with a low duty cycle of <5%. (on time ~5 sec in a 30 minute window). I prefer to use a transistor based astable multivibrator (base coupled mode). Are there any guidelines on the selection of values for base resistor and capacitors? Is there any advantage in using an NE555 based astable multivibrator as compared to transistor based one?


texts: Why do relay contacts open when connecting a dc motor on the switch contacts?

texts:
The circuit simply goes like this:

The base of the transistor is a logic signal which came from an external circuit supplied by the same 6V source as that of the collector. The logic signal can either be 0 volts or 6 volts. The external circuit consists of a PIC and an op amp.

The 6V supply come from a 6V lead acid battery. Also, I used different voltage supply on the transistor and the dc motor, so I used two 6 Volts battery in all (including the external circuit), separately.

Without the 3 Volts dc motor, the relay switched properly when the input is logic 1 (6V), and closed properly when logic 0 (gnd). So, no problem with the relay.

The problem is: With the dc motor attached on the switch contact of the relay, and a logic-1 is applied on the input, the switch on the relay repeatedly opens and close (that is, the dc motor rotates and stops repeatedly).

I tried forcing the value of the input to 6V without the external circuit that produces it. The dc motor rotates perfectly fine in that case.

My first thought was that the battery is drained or absorbed (that is, the supply lowered down to 3 Volts when measured) because of the external circuit that produces the input to the base of the transistor. If I am correct with my assumption, how would I eliminate the absorption of the battery?

I tried replacing fully charged 6V lead acid battery but the problem remains the same. How would I solve this?

If you need more info, you may comment below. Sorry I may use wrong terms because I am not an expert on this field.


texts: Can I use a deserializer without a matching serializer?

texts:
I am trying to connect an LVDS output to an 18-bit parallel input. Ser/des ICs like this all state on their datasheets (like on page 12 of the linked datasheet) that before they are able to function they "must initialize the links to and from [a matching ser/des]". Can this matching ser/des not exist and the data be generated from a different device entirely? The data is sent as 0b1 - 16 bits of data - 0b0.

If not, how would I go about deserializing the data? I thought about using an LVDS receiver such as this to recover the LVDS clock (which is also given as an LVDS output) and the data as single-ended signals and an 18-bit counter driving a multiplexer linked to 18 flip-flops. Would that work? I am a bit worried about timing, since the LVDS clock is 18x faster than the reference clock of the data source. Is that the "cleanest" way to go about it? I am trying not to use an FPGA and stick to discrete parts.

Thanks in advance!


texts: Connect kindle 3 serial port to epson printer's 8 pin mini-din serial port?

texts:
I have a kindle 3 with a broken screen and an old EPSON stylus 1520. The kindle has a serial port with TX, RX, GND and 1.8v VCC (source). The printer has a mac compatible 8 pin Mini-DIN port.

Would it be possible to connect the kindle to the printer? I saw some pinouts for 8 pin mini DINs, and some of the pins were labeled something like "handshake", so I guess it's not as easy as connecting TX<->RX, RX<->TX.

I don't have a computer with a parallel port to connect to the printer. I haven't done this kind of thing before, so any advise and/or links is appreciated. I haven't found any material on how to connect them together, perhaps I'm missing the right keywords, or it can't be done.

Edit:

I have a computer with an round 4 pin port with an S next to it, that I think is for S-video, which uses the same physical port as ADB. Could I connect the printer's serial port to that one? I guess the S-video can't speak RS-232?


texts: PGA2311 Digital Power Supply (+5V) shared with other ICs or not

texts: I am working on Audio Volume Controller, based on Texas Instruments PGA2311 Stereo Audio Volume Controller. Among other pins, this IC has also Digital Power Supply (+5V) Pin. Can I use these +5V from power supply also for other integrated ciruits on PCB (beside powering PGA2311) or should I consecrate one power line for PGA2311 and one power line for other ICs? I am aware of current capabilities of regulator, I am asking if quality of audio signal reproduction would have suffered if I shared power line among all ICs (digital) on PCB.


texts: RFID car tags vs hand held tags, how exactly are they different?

texts:
The basic principle of RFID tags in cars for toll collection is the same as the hand held tags we use to open doors.

How exactly are they different? How come my door RFID reader does not read my tag at 10 meters away while i run at 100km/hr :)

Can someone elaborate on the differences in the two systems for them to work the way they do? Am i being blasted with high powered radio frequencies when i pass a toll RFID reader?


texts: Why is root mean square used when calculating average power, and not simply the average of voltage/current?

texts:
$$P = I_{\text{eff}}^2 \times R$$ where \$I_{\text{eff}}\$ is the effective current. For power to be average \$I\$ must be average current, so I am surmising that the effective current is the average current.

In that case, why is \$I_{\text{eff}}\$ not simply $$I_{\text{eff}} = \frac{1}{t}\int_{0}^{t} |i|dt$$

Instead it is defined like so:

$$I_{\text{eff}} = \sqrt{\frac{1}{t}\int_{0}^{t} i^2dt}$$

Thus, using these two expressions to calculate \$P\$ results in different answers.

Why is this so? It makes no sense to me. I can only guess that I am misinterpreting the effective current is the average current. If this is not the case, however, I do not see how \$P\$ can be the average power when \$I_{\text{eff}}\$ is not the average current.


texts: How to connect a 4-pin OSC (crystal oscillator) to an IMU (BNO055) with only 2 pins dedicated to an external clock?

texts:
I am using the BNO055 :
https://cdn-shop.adafruit.com/datasheets/BST_BNO055_DS000_12.pdf
and I can't seem to figure out how to connect a standard external oscillator clock to the chip. As suggested, I will use a 32 Khz oscillator.
There are generally 4 pins on the oscillators that I have researched: the VDD, GND, Output, and DNC. I get that the DNC is left floating, but how do I connect the remaining 3 pins to the 2 lines on the BNO055 (XOUT32 and XIN32).

Also, will it work if I just connect a standard clock to it rather than an oscillator?

Any help would be appreciated!


texts: Use bipolar transistor to power LED from a certain power on?

texts:
I'm trying to do the following: I have a LED that is supposed to be on, whenever a control voltage (CTRL) exceeds a certain voltage (0.7V). To do this, I created the following circuit:

I know that a bipolar transistor is controlled by the current, not the voltage and it's probably not the best way to go here. However, it is actually working quite well - except for one thing: When CTRL reaches ~0.6V, the LED is slowly starting to go on until reaching its final brightness at about 0.9V.

Is there any way to make this junction more abrupt - even with an BJT? So the LED does not seem to fade in and out anymore? Maybe I should mention that CTRL itself slowly ranges between 0 and 5V.


texts:
I am planning on building a vintage tube radio from schematics.  Part of the radio will include its (multi-voltage output) power supply, with an AC power cord, AC switch, and transformers.

Are they any (U.S. legal, regulatory, or commonly accepted good engineering practice) standards that I should follow in sourcing the components (transformer specs, type of cord, fuses, etc.), and performing the wiring and assembly? (soldering, connectors, insulators, shielding, etc.)

The goal would be to end up with a radio that is safe for myself, a family member, or a guest to operate.


texts: How to get signal dependencies from RTL verilog?

texts:
How can I find out if a signal B has any combinational dependency on a signal A without manually examining the verilog source code?

(Question edited to try and make the reason/background more clear)

In a complex design it can be easy to make mistakes and incorrectly get a dependency on a slow (but functionally correct) signal that is hard to notice or spot later. I'll try to draw a (highly simplified) example:

Preferred logic:
           ___________
A_FAST --->|--logic--|---> B_data
           |         |
A_SLOW --->|--logic--|---> B_en
           ¨¨¨¨¨¨¨¨¨¨¨

Accidental logic:
           ___________
A_FAST --->|  logic--|---> B_data
           |   ^     |
A_SLOW --->|---/-----|---> B_en
           ¨¨¨¨¨¨¨¨¨¨¨

A_SLOW has accidentally sneaked into the logic and is not needed to determine B_data. However the timing for B_data becomes much slower than it has to be - it would be much better to use A_FAST. I would like to set up some check or assert to find unwanted combinational paths and so my question is:

Is there some easy way to find out if B_data has any dependency on a A_SLOW?

Perhaps get a list of all signal dependencies in the verilog rtl design? (Because that would be easy to scan through)


texts: can anyone help me with this part? : ADC81S021

texts:
i googled the P/N and can't even find who the manufacturer is and, what i really want, is a spec sheet.

it's in a board already, and someone just sent me an iPhone photo of the board schematic.  i can tell it's hooked up to the SPI of the DSP i am using, but i don't have any idea what the input voltage range is (Va is 3.3v so i suspect it's 0 to 3 volts or something) nor the protocol of the bits coming out (MSB/LSB first?) nor even how many bits?  or the samples per second or conversion time?

it appears to be a very cheap part, only 6 pins, and when you consider the SCLK and CS, i don't think it has any pins to spare.

but i can't find a single site for the data sheet on this thing.  and that surprizes me.  i found one site that sells it, and then a couple of sites that sell a product using this part.

where can i get a data sheet?  who even is the manufacturer?


texts:
I'm putting together a simple DTACK circuit for a 68k homebrew machine, and part of that is requires me to know when either the Upper Data Strobe (UDS) or Lower Data Strobe (LDS) is asserted LOW. I've only got a few random ICs to hand, so I'm attempting to use a 7408 AND and driving the output into two inputs of a 7402 NOR gate.

For some reason the output of the AND gate seemingly isn't correct, it seems to miss pulses and I don't know why. It's a fast chip and I believe we're way within it's tolerances so what should I be looking for?

The output below from my logic analyser shows 3 address lines (D0-D2), UDS & LDS (D3 & D4) and the trace from the bridge between the two NOR inputs (D5) (the same signal is present directly on the output of the AND). I know unused inputs should be tied LOW or HIGH but I assume that's when an input isn't used for an individual gate in a quad package?


texts: Induced-EMF due to the induced magnetic field of a wire?

texts:
If a current carrying wire is placed inside a magnetic field(B), the wire will produce it's own magnetic field that will oppose the applied external magnetic field(B). Due to the two fields opposing one another, would that somehow change the ϕ acting on the wire inducing an ϵ to oppose that change?

I'm aware that this wire would experience the Lorentz Force, and from that will move and from that motion, there is induced ϵ = −vBL.


texts: Is this a reasonable circuit for locked antiphase PWM?

texts:
I'm building a motor controller for a robot that will have a very limited number of IO pins available. I need to drive two motors from only 3 pins, and Locked Antiphase PWM, where the motor is alternately driven forward and backwards by the H-Bridge, with duty cycle determining the net current, looks very attractive. The fact that it 'just works' when the robot is on a slope (rather than accelerating down it when given a small forward momentum) is an added bonus.

Does this circuit, utilizing the SN754410 H-Bridge and a couple of transistors used as inverters, look reasonable? Am I doing anything obviously wrong here?

Also, a couple of auxiliary questions:

In 'regenerative braking' mode, the motor may drive current back out the H-Bridge. If I'm powering the whole circuit off a (non-rechargeable) battery, is this liable to damage the battery? If so, can I protect against it with diodes?
How can I determine what frequency of PWM I'll need to avoid significant idle current draw with Locked-Antiphase and a given motor, other than experimentally?


texts: How to find the critical path delay of a big combinational block

texts: I have a 54*54 multiplier, i want to find the critical path delay.how do i go about, should i clock the module in order to find the delay?


texts:
My professor went over this problem in class today, but I had trouble understanding it even after a few questions were asked.
The goal was to find the voltage, \$v_i\$ across the 8Ω resistor on the right. The math on the right is what was put on the board in class.

What I don't understand is why we would use 2.4Ω in the numerator, when we want to find the voltage across the 8Ω resistor. Isn't this the wrong proportion? If 8Ω was in the numerator, the answer would be 20V, so it definitely makes a difference which one you use.

Why can we use the 2.4Ω resistor in this situation?


texts: deciphering schematic and diagnosing fault in cine camera circuit

texts:
I'm trying to understand part of this schematic in order to diagnose a fault with the light metering on an old (circa 1974) Nizo super 8 cine camera (other functionality appears to be ok). I appreciate this may be too specific to be of interest in this forum; apologies in advance if so. I have a number of questions - feel free to cherry pick any easy ones, all help appreciated.
The schematic is rather fuzzy because it is a blown-up photo of one printed inside the camera - the original is not much bigger than a large postage stamp.

(source: bigbluewave.co.uk)
The most directly relevant parts of the schematic (I think) are near the top-left: the "arrow-in-circle" symbol and the symbol labelled PW and - to the right of that - the three-part rotary aperture-control switch, trim pots and diode D3. (M2 and the switch in the top-left corner I think is the powered zoom control. It works. I don't really know if this has any relevance at all.) I'm guessing that the arrow-in-circle represents the light meter display and perhaps PW is a photocell. The middle section (S5) of the three-part switch is supposed to activate a battery-test function (hijacking the light meter display). I have verified that S5 is ok (ie it is closed circuit when the switch is turned to the battery-test position and open otherwise). The power supply is 6V.
With the power switch off, the meter points to a mid-range value. With power on, the meter swings to its minimum reading (and the camera iris opens fully) and stays there, regardless of the light level or the position of the aperture-control switch, including the battery-test position.
Questions:

What is the symbol labelled PW? Google has failed me so far. My current guess is a photocell.

The rotary aperture-control switch has two discrete stops (battery-test and "autom") and a continuous manual adjustment region. I'm assuming that the arcs at S4 and S5'' are variable resistors which come into play in manual adjustment. Does this seem reasonable? (Again, the symbols don't seem to be in common use.)

Do the symptoms point to any of the solid state components as likely culprits, or should the switches S4, S5'' be my prime suspects? I've already determined that D3 (1N4148) is ok (but I think D3 is only relevant to the battery-test function).

More specifically, given that engaging the battery test has no effect, does it seem likely that the photocell is not the problem? (My reasoning is that the battery-test switch could be expected to bypass the photocell.)

Clearly the schematic is only part of the story (no component values, etc) but it's the only documentation I have been able to find. Any suggestions as to what those pairs of points labelled D D and S S might signify?

How is the light-metering circuit supposed to work (in outline)? A bit general, I know, but the truth is that even if I already had the answers to 1-5, I don't think I would really understand the basic idea of the circuit.


texts: PIC24EP: What exactly are IOL, IOH currents

texts:
I'm going through the 'Electrical Characteristics' section of datasheet of PIC24EP128GP206 to find out minimum and maximum voltages and currents specific to GPIO pins.

While doing so, I came across the terms IOL, IOH in the following section:

What do the IOL, IOH currents exactly represent?
Are these the sourcing / sinking currents associated with the output pins?
Why is the IOH limit is mentioned negative?


texts: What is the time axis array after we convolve two functions in Matlab after sampling it with frequency \$f_s\$?

texts: Suppose we have a continuous time function \$f(t)\$ , we sample it at frequency \$f_s, (t = -5:1/f_s:5)\$, and store it in an array \$a\$ in Matlab. Now we convolve it with itself using \$b = conv(a,a)\$. What is the new time axis array for the convolved function stored discretely in array \$b\$ ?


texts: Probably overheated black color SMD pads

texts:
Can you give me an advice what to do with probably overheated SMD soldering pads on the board?

The photo is of a computer bus card, where there are 4 SMD 0603 positions labeled R1 - R4. They are used for configuring the card frequency from 20 MHz to 40 MHz.
These positions should be bridged by  0 ohm resistors.

I wanted to reconnect the R2 and R4 positions. I used a soldering station with iron and controlled temperature and electrical 1mm thin solder. I set the temperature to 350 degrees Celsius.

I didn't have SMD resistors, so I used just thin wire as I have seen in a web page.
However it looks like I overheated the pads - they are a black color and I can't wet them any more with solder.

I know I should have better solder with hot air soldering unit and solder paste.

I found the same problem described in this forum thread http://eab.abime.net/showthread.php?t=76132
The guy there wanted to increase frequency from 33 MHZ to 40 MHZ on the card but he destroyed the pad like me.
Then he found the right pins for R1 pads on ICS511 chip and reconnected the pins 6 and 7.
I say ok, 33MHz should be enough.
Now can you give me an advice how to solder two pins together ?  Is it enough to use only small amount of solder or should i solder thin wire to the pins ?
What about using the electrical conductive wire glue ?
Or electrical conductive pen is enough ?


texts:
I am implementing a circuit as shown below :-

Source is a 15V Solar panel & Load is the Battery. The intent is that if someone tries to connect a bigger battery on the output, Diode(Schottky is what coming to my mind) shall block reverse flow being reverse biased.

In normal scenario, all the current will pass through forward biased schottky diode. The rating of the system is 15V/20A. Upon looking into few schottky diodes available, which have a forward voltage drop of about 400mV, the power dissipation is coming out to be Vf*If = 0.4V*20A = 8W which is a lot of power to dissipate.

Am I using the right approach?? Any suggestions here.


texts: Why is the Irms so different from Isat in different power inductors?

texts:
I'm looking at power inductors for a DC-DC boost converter clocked in the 500KHz range (but KHz could change if necessary).  Here are two examples:

Example 1: Irms=55A, Isat=140A, 70nH
Example 2: Irms=74A, Isat=65A, 70nH

In both cases they are rated at +40°C.
Questions:

Why does Example 2 have a higher Irms than Isat?
What causes Example 2 to be the opposite of Example 1?
Other considerations?


texts: Can i connect batteries (both 12v and SLA) of different amperage (100amp with 180amp) in parallels?

texts:
I have a 250W solar panel connected to a 12V 100A (SLA) battery through a charge controller (12 and 24V). A 1100W inverter is also connected to the battery.
Now I want to connect a 12V 180A battery in parallel to it. Is it possible? What effect will it have on the batteries?


texts: 9v battery voltage drop and regain its voltage

texts: as a part of my project , i have to develop +5v from an 9v carbon-zinc battery with 7805 regulator.it is given to microcontroller and some other circuitries .it consumes nearly 40ma. but,the problem is that " battery voltage drop fastly to less than 6v for continuous usage,nearly 20 minutes".then 7805 wont work and entire system will shut down. after,removing the battery,battery voltage increases from 6v to 8.5v and again performs well for next 20 minutes. i would like to use at least 1 hour continuously,without effecting performance.can you suggest a proper solution?


texts: Testing cable continuity while protecting from overvoltages

texts:
I have a circuit that tests the continuity of all the wires in an A-B USB cable, by plugging both ends of the cable in female connectors on the PCB.
It is operated by a 3V3 tolerant MCU.
That creates a risk of damaging the chip by inadvertently plugging in a cable that was already plugged in a computer port, injecting 5V on the chip and breaking it (it already happened.)
I want to design a protection circuit that won't prevent current from passing from A to B, and B to A.
Simply putting a diode on the VCC pin of the B connector would prevent me from testing on both directions, however I would like to be able to do that.
Is there a possible way to prevent 5V from reaching the MCU, while still being able to pass a 3V3 signal? Maybe something like a diode that would only trigger over a certain threshold voltage?


texts:
simulate this circuit – Schematic created using CircuitLab

Is it OK to drive a Delta Load with a Wye Source?  In my case the scenario is that I have a heater that has three resistances in a Delta Configuration.  However, our service entrance to the plant is a Wye.  Let's say it is possible(?) is there any downside to doing this?  Finally, the Delta Load is "isolated/floating" in a metal housing ( the heater enclosure ), should the Neutral wire from the Wye be tied to the metal case of the heater enclosure?  Thanks in advance...


texts: Pulse-Amplitude Modulation minimum clock frequency

texts:
Below is the question and answer:

Source:
Study Guide for Fundamentals of Engineering (FE) Electrical & Computer CBT Exam- Third Edition By Wasim Asghar, ISBN:9798670880909
However, as per the below book it's given as :

Source:
FE Reference Handbook 10.0.1, by NCEES, ISBN 978-1-947801-11-0
It clearly says that the signal can be generated by the sampling frequency i.e. the correct answer is 15 kHz.
Am I right?


texts: Firing Anti-parallel Thyristors with continuously firing pulse-trains

texts:
Can I use two pulse trains as describe below to fire a set of anti-parallel thyristors? Is there any potential danger in this firing scheme?

PS: I must use pulse train firing in my application.


texts: What type of electronic hardware is best suited for high temperature applications?

texts: What type of electronic hardware is best suited for high temperatures, roughly 200°C? From what I've discovered, most FPGAs, microprocessors, and DSPs have an operating temperature of 70°C or below. So what type of digital or analog circuitry should be selected for operations at 150°C or higher?


texts: How can an active rectifier block current?

texts:
This is a 2 part question for my understand about how an MOSFET/IGBT based active rectifier controls current.

1) Assuming a 3 phase active front end to a DC bus, and some huge load on the DC bus attempted drawn below. (Only 1 phase drawn, ignore exact values)

simulate this circuit – Schematic created using CircuitLab

Once the short/big load makes the DC bus voltage drop, won`t this effectively become a passive rectifier through its diodes? Which in turn would give it no way of blocking its current?

2) In normal operation I assume its diodes also works as passive rectifiers. With its transistors are only used for boosting input voltage...?


texts: Why is the common lead of unipolar motor connected to the high level voltage?

texts:
I'm trying to gain a deeper understanding of DC stepper motor because I'm using them for an arduino project.

I was wondering about why the common lead of unipolar stepper motors is usually (always?) connected to the high level voltage instead of ground.

Connecting it to ground should be the most logical thing to do, however, it is not the case.
Of course, both cases should work fine for the motor, it just changes the controlling sequence, so that's not a big thing. But is there some advantages, some hidden motives to connect it to the high level voltage?

For reference: I'm using a 28byj-48 stepper motor (5 wires)


texts: Flash memory corruption due to electricals?

texts:
I'm a software developer working on an in-vehicle (WinCE) device that uses an SDIO card for its storage.

We are suffering from (seemingly) random corruptions of the data, seemingly from the FAT table getting corrupted.  You may find inaccessible directories, files with "junk" half way through them, and so on.   The card does NOT seem to suffer from physical damage (bad sectors) - a chkdsk fixes the FAT in most cases (the data of course is in trouble).

This sounds like a classic case of power loss in the middle of writes, so we've implemented a fair bit to combat that scenario.

We now have electronics to notify us that the master switch has been turned off, and give the application running on the device enough time to shut down cleanly.

Despite all that, we still have the problem.  We seem to see corruption, even in the absence of a "dirty" shutdown.

Assuming for a second that the software side is all correct. Is it within the realms of possibility that momentary spikes, brown-outs,or other irregularlities in the power supply could cause what we're seeing?   We have filters etc. in place to shut

Is it possible the ESD/electromagnetic interference could cause any of the above?  Any other thoughts from an electrical/electronics side?

Much appreciated.


texts: What kind of glue should I use for PCB-mounted components to increase rigidity and stress relief (not vibrations)?

texts:
I have some small boards that have various connectors, JSP, female headers etc. Those connectors and headers will be used a lot with various devices plugged in and pulled out and will get a lot of mechanical stress. This will be rotational, angular, perpendicular, you name it.
I understand that a lot of stress is directly on the pins and not the housings, but I want to be able to glue down the plastic housings to the PCBS for extra strength.

Neutral cure silicone rubber won't be of much use to me as I'm after rigidity and strength not vibrational relief.

I've tried high viscosity super glue and it's been useless. The same with one brand of UV adhesive. They both allowed the component to snap off with very little effort.
I've yet to try forms of epoxy as with small but frequent jobs like this there will be a lot of waste during mixing and it will end up being relatively expensive.

Suggestions?

Thanks.


texts: I tried connecting the one on the left with the 4 pin fan connectors on my computer PSU, but they are not compatible.


texts: what limits the maximum voltage of this optocoupler (6N137)?

texts:
In the datasheet it is stated that the maximum VCC voltage is +5.5V.(https://www.vishay.com/docs/84732/6n137.pdf)

Because ive been told to question everything (and i have enought of them to kill one or two) i used it with 12V. It works great as it should. Now what should be limiting the voltage and what could happen if ill use it at 12V?


texts: How can two electrical sources 220 volts feed one electrical load about 20 amperes where the first  power source spends all its capacity and when required the remainder is taken from the second source?


texts:
I am trying to wire up 3 NEMA 23 Steppers driven by 3 DRV8825 drivers and an Arduino Due. I tried to solder a perfboard prototype, but when I turned it on the first board burned and the ground jumper (red wire at the top in the picture below) started smoking.
I had this issue before when I wired one driver on a breadboard. I fixed this by powering the driver with an adjustable DC power supply, and making sure that worked before switching back to the 24V DC power supply. This time, I successfully tested the setup with 3 drivers on a breadboard with the 24V supply, and set the current limiting potentiometer to the correct value (all less than 1.6 A).
I took the same setup and transferred it to the perfboard. I checked for shorts by testing for continuity with a multimeter. The one thing I did not do is test the perfboard with the adjustable power supply (oversight on my part).
I am definitely an electronics amateur, so I may be missing something obvious. Why do I keep on frying boards? Some things that I think could be the problem:

I need 3 capacitors instead of 1, and I need them closer to the drivers.
Bad power supply.

I made a wiring diagram of the setup, and took pictures of the perfboard below.


texts: STM32 non-blocking mode UART reception with HAL driver

texts:
I'm learning micro controller using STM32F429I-DISCOVERY board and have a question about non-blocking mode UART reception.

I compiled this example project(UART_TwoBoards_ComIT) and flashed the STM32 board with the binary file. Then I connected the UART1 pins on the STM32 board to Beaglebone Black's UART1 pins. The Beaglebone Black board uses Debian linux and a serial monitor 'minicom' so that it can communicate with the STM32 board via UART.

Then I could see " ****UART_TwoBoards_ComIT****  ****UART_TwoBoards_ComIT****  ****UART_TwoBoards_ComIT****" from the serial monitor. Up to here everything looked fine. But when I type a random letter  in my serial monitor, I can't see that LED3 is toggled. I checked that the TX pin of the Beaglebone Black outputs digital signals at that time. I guess that the STM32 board doesn't receive any data from the Beaglebone Black board and enters to infinite loop, but I'm not confident..

Could you please explain why the LED3 is not toggled, even if my Beaglebone Black sends data to the STM32 board?


texts:
I am trying to get a better understanding for RAM and Flash and I hope you could help me out with some things.

What I know about Flash (or at least I think to know), is that there are different Flash structures.
With structures I mean NOR and NAND Flash e.g.

Independent of the structure I can store data in the Flash. I know there are some differences between NAND and NOR Flash like density if I understand it correctly but I am still not understanding when NOR Flash should be used and when NAND Flash should be used.
What are the advantages of the structures and would it be an issue if I would replace a NOR Flash in a system with a NAND Flash that contains the same data for example?

What I know about RAM is that it's way faster then Flash and once the power is turned off its memory is "erased".
That's it. Something that I am especially wondering about is if there are different RAM structures, too? Does something like NOR or NAND RAM exist?


texts: First time making pcb using photoresist...not sure if I am starting out right

texts:
Haven't pulled the trigger on my first attempt to make a pcb using the photo-resist method.  Here is my setup.

Created the board layout in Eagle (free version)
Purchased photo-resist from ebay - seems there is no information on the product I bought.
Purchased positive developer from MG Chemical

My first attempt seemed to indicate that the layout transparency needs to be a negative image (traces clear and background black)  Is there something I should have done to be able to use positive images?

I made a small exposure box using 180 UV LEDs and it seems to expose the film in about 10 minutes.

Is there a way to get Eagle to print negative images of the payout artwork?

What should I look for in photo-resist and developer if I want to develop from a positive image?

I've seen a few YouTube tutorials that show the exposed photo-resist being developed using sodium carbonate.  Is that better or not as good as using MG Chemical positive developer or did I miss understand them entirely?

Is there something I should be using instead?  Unfortunately there is so much info on YouTube and the web that is not consistent and hard to figure out who to listen too.


texts: How to calculate current and voltage draw of a single resistor circuit?

texts:
If I have a single 270 ohm resistor connected in a circuit to a 3.3V 50mA power supply, how can I measure the voltage and current for the resistor? I'm familiar with Ohm's law V=IR, where V is the voltage differential, but what is the differential for a resistor?

I'm trying to work out why when I put a blue LED (3V@20mA) into the circuit, the voltage I actually measure is less than 3V (more like 2.4V).

Update

I think the thing that is confusing me is the discrepency between the theoretical values, and the measured values.

Theoretical values:

  I = V/R
  I = 3.3 / 270
  I = 12.222mA

Measured values:

  3.28V
  267 ohm
  11.7mA

But then if I plug the measured values back into Ohm's Law, they don't equate?!

  I = 3.28 / 267
  I = 12.28mA

  V = IR
  V = 0.0117 * 267
  V = 3.12V


texts:
I am looking into fitting ferrites to my SMPS power supplies output leads  (wall warts.)
I have been getting some strange noises on my valve stereo amplifier since using a couple of LV DC PSUs as above. One for Bluetooth and another for a Cambridge audio D.A.C.
Is it a case of just fitting the clip-on cylindrical variety or taking a given number of turns thru each device?
I have tried a single pass but this seems to give no obvious improvement. Also will a number of (effectively) ampere turns affect the SMPS loading?
If I remove the SMPS supplies all is well so am sure  the high frequency noise is due to these (nssty) SMPS devices. If this is the case I will have to invest in a proper linear PSU.


texts: Does it matter which side I place the bulb in a circuit?

texts:
For example, will it matter if the bulb is in this position:

simulate this circuit – Schematic created using CircuitLab

or this position?

simulate this circuit

Also, if it wouldn't work in either position, why? I mean, in the second, charged electrons are still being passed through the bulb, right?


texts: Increasing the surface area of an electro magnet

texts: I am trying to design an electro magnet with a large surface area at the end.  The first design used a 1/4" rod wound with magnet wire resulting in about 10 ohms of resistance driven with 12 V.  This produced a fairly strong magnet with a small area at the end.  My desire is to create a magnet of similar strength but with more surface area at the end to allow for easier location with another magnet.  So I soldiered a 1"x1" plate of approximately 1/8" thickness to the end of the 1/4" rod thinking that the flux would then spread out over the area.  It turns out that the magnet has very weak magnetism on the surface but is strong around the edges so I think that the plate is directing the flux to turn and flow out of the edges (not the desired effect).  I know that I could just increase the diameter of the rod to say 1" but this will cause the magnet to weigh more and reduce the number of turns.  It there a way to couple the small diameter core (i.e. to get more turns) and spread out the flux at the end over a wider area without the flux being drawn to the edges?


texts:
I found with search for electromotor ageing effects site:electronics.stackexchange.com only DC Motor Friction Torque, saying:

  In general, motor frictional losses are ignored - if you have to take
  them into account you're working too close to the edge.

Relative of mine said washing machine started to work poorly (worse water removal) and gave hypothesis that the motor started to work worse. As I understand engineering of electric motor, the power cannot decrease from ageing of wires etc, motor just fails completely. If post noted above is correct, then ageing of bearings cannot be the problem too. I am not sure about degradation of brushes (if motor is not brushless).

Can electric motor power/torque decrease with age to any practical significance degree?


texts: Transformer - I connected 50k resistance which burnt - why? AC

texts:
Wall supply gives as much power as a component uses.
I'm trying to connect a 800W transformer to produce an arc of electricity. But I can't exceed 10A because home fuse will triger (so every device will be instantly cut from electricity etc).
So I want to know, what will be the amperage, should be 800W/230V = 3.48A right?

However what causes the transformer to be 800W - it doesn't drain energy directly as a bulb does. It produces electromagnetic field and the "amount" of this field is indicated by number of scrolls I guess, but is it also increased by it's resistance?

I want to be sure that adding 1M*2 resistance would make it drain P=I^2*R, I=(800/2M)^(1/2) = 1/50 = 0.02 A and that wall supply won't somehow try to compensate 2M resistance and increase amperage to like 800A.

To do so, I connected an analog amperage meter 0-1A and a 47k ohm resistor, it should be I = (800/47000)^(1/2) = 0.13 A. And U = 6132V.
When I connected 2M ohm, nothing has happened, it should have been U = (800*2M)^(1/2) = 40k V right? Maybe then increased 10 times as it's a MOT, 1000:100, so 400k V... But the resistors didn't burn.

Why did 47k burn and 2M not, in spite of 6k vs 40k voltage?

simulate this circuit – Schematic created using CircuitLab

Used MOT:
MD903-EMR-1
Class 220,
230V 50Hz

I didn't count the turns on each coil, but because it's supposed to give over 2k V output, I guess it has 100:1000 ratio, considering one of the coils is really thicc and the other is rather thin, eye-estimation that is.

Also it might be a 900W not 800W


texts: I have been thinking about an inductor made out of superconductors, would it work? How would it affect the total inductance compared to a normal inductor? Would it be possible to calculate such a device with a formula? (I'm not an engineer yet, I'm a student so be considerate of that)


texts:
I am trying to implement the LTC4361 chip using opAMPS on a bread board. There is a statement which reads - "V trip threshold and
a 10µs glitch filter" (page 6 of datasheet).

How can I implement a glitch filter ?
If I understand right, a glitch filter is something that filters out small ripples. The 10uSec means any ripple <= 10uS is filtered. Can I not do it using a ceramic cap and with the 1/2.pi.f.c formula, find out the waveform or filter properties ?

I intend to do that in spice. Is my approach right ?


texts:
I'd like to know if this demostration is correct to calculate Gmo2 from vout about differential amplificator from this diagram :

1 : Gmo transconductance about Common Base configuration

2 : Gmo1 transconductance from T1

3 : Gmo2 transconductance from T2

with
4 : Rout from output (vo)

5 : Rin from ib1

B11 : BAD diagram - Measure of vout with the half of gm

B12 : Good diagram - Measure of vout with the half of gm

simulate this circuit – Schematic created using CircuitLab

Link
B21 : Bad diagram Measure of vout with the all the gm

DC Op

B22 : Good diagram - Measure of vout with the all the gm

Link


texts: How to design connectors when I do not know what the customers want?

texts:
My PCB needs to export four sets of voltages to our customers' PCBs. Eight pins in total are needed. Eight pins at my side are to be connected with eight pins at customer's pcb side. Our pcb is to be integrated into customers' system. The system will be put into a box and made a lab device. So I guess stable connections are important. Or during device dilivery, the connector may get disconnected.

However, i do not really know what the customers' connectors are.

Shall I use 1.27mm spacing or 2.54 spacing? At my side, 1.27mm spacing is preferred, which brings to smaller size of pcb. However, 2.54mm spacing seems more common and is compatible easily with ribbon cables.
Shall I use connectors that have directions? Connectors with direction connect more stable. However, the customer has to use the same connector.

I have little experiences designing product. Any advice will be really appreciated!


texts:
I'm working on a design which needs a 9V supply. This is currently provided by a 9V battery, but I'm looking to change to a lithium battery (3.3 to 4.7V).

This supply has a pulsed load of up to 2A, with a pulse width of 10 to 300 us pulsing at a frequency of 2 to 200 Hz. The maximum average current is only perhaps 40 mA or much lower, but it's coming in huge spikes.

I don't have much experience with boost converters. I've been considering the TI LMR62014, which switches at 1.6MHz.

My first thought is to use a resistor and a large capacitor to smooth the average current through the converter.

simulate this circuit – Schematic created using CircuitLab

Is this the right approach? Is there any glaring problems with it?

My other thoughts would be to implement a constant-current device (which would probably increase the part count quite a lot), but I'm open to any thoughts or suggestions.

Thanks!


texts: LED Strips - Data Noise Over Long Distance Between Controller and First Strip

texts:
Please refer to the above picture.

The black line is the ground wire and the green line is the wire carrying data.

First Question

In regards to data noise/interference, can the output ground wire of the power supply and controller be connected at the blue circled part instead of the purple circled part given that the distance between the controller and the first led strip is 11 meter?

Second Question

If the answer to the above is yes, does using coaxial cable for ONLY the data wire help in reducing interference? We are unable to use twisted pair for the ground and data wire and the ground is shared between the power and the data.

Third Question

Does it make a difference in terms of data noise/ground loop if the data and ground are wired as per diagram 2 instead of diagram 1?

Thank you.

EDIT:


texts:
I am having trouble finding a device or circuit which will help me on my quest to control the maximum output of a circuit, with a varying voltage produced by a potentiometer.

If lets say, I have a 5v reference voltage, changed to 0.25v-4.75v by potentiometer, and I wish to limit the output voltage to 3.75v, how would I go about this? I have looked into zener diodes but they only work with dropping voltage from a higher to a lower amount. Resistors are no good due to ohms law, the voltage is variable. Any ideas?


texts:
As I look at the Datasheet of a differential amplifier for input impedance, i see below statement.

0.8||2 for Differential.
0.4||2 for Common mode.

What does GΩ||pF mean?


texts:
I am using a Stellaris EK-LM4F120XL for a project.
The project includes an LCD module, servo motor, ultrasonic ranger and a numpad.
The LCD, servo and ranger are rated at 5V operating voltage, and the Stellaris at approx. 3.3V.
To have the project powered as a stand alone unit, I have a battery pack for 2x9V batteries. I will hook these in parallel to offer a longer running time. Then they will flow into a voltage-regulator, LM317, to provide 5V to the peripherals..

Then I will use this 5V source thru a non-inverting hex-buffer, CD4050BE, to then power the microcontroller.. I understand that no matter what voltage is input - the difference between Vcc and GND is output. Although, does that mean for a buffer you need to have a voltage-in, and a desired voltage-out - but also need to supply a Vcc voltage to maintain the desired output?

Therefore, if I have my 5V source from my regulator, do I really need to create circuitry using a resistor-divider or transistor voltage-drop, to get my 3.3V - then input this into the hex-buffer..? What a waste of current, no?

Why not utilise another voltage-regulator with voltage-divider resistors like I used to get my 5V..?

What about a single-channel linear-regulator - LP2950-N, of 3.3V variation..?
Or LM2936-3.3...?
Why use buffers at all then.. instead of regulators..?

I have diodes/resistors/PNP BJTs/opAmps on hand..
I am using transistors, BC548, to operate my 'loads' that are in parallel with diodes already.. And will ground everything to the same point - negative terminal of the powerpack..

To clear it up - I need 5V for all peripherals, and approx. 3.3V for the uController..

Cheers :-)

(I have circuit diagrams but cant add pics..?)


texts: Setting current on Diodes Inc PAM2863 LED driver IC, with external resistor AND driving different voltage to VSET

texts:
I'm looking to use the Diodes Inc PAM2863 DC-DC LED driver in a project.

The datasheet gives a V=IR method for setting the average output current with an external resistor, where Iout = 0.1 / Rs.

However, it then says,

  "The above values assume that the VSET pin is floating and at a
  nominal voltage of VREF (2.5V). Note that Rs = 0.1Ω is the minimum
  allowed value of sense resistor under these conditions to maintain
  switch current below the specified maximum value. It is possible to
  use different values of Rs if the VSET pin is driven from an external
  voltage."

It doesn't give any other formula for setting the output current with a different voltage on VSET, and my microcontroller will be sending 5V.

How would I adjust the current formula to find the new resistor value?
I need to supply more than 1 amp, so I can't just reduce the signal voltage.

Thanks in advance


texts:
I am trying to make a low power device (based of RSL10 bluetooth SoC) that would sample a strain gauge @1kHz and transmit the measurements. The current drawn by the running SoC is about 1.5mA, while the current for the gauge excitation is about 3mA (1kOhm @ 3VDC) assembled in a 4-gauge Wheatstone bridge.

I wish to keep the gauge current in sub-mA current range, but they seem to not make stain gauges of higher resistance. I think the ones I have are 350Ohm each with some additional resistors to make it to a 1kOhm.

I could add more series resistors outside the bridge, but I think this will make the assemble less sensitive to changes.
Another option is using a buck converter to step up the excitation voltage, but this procedure would not help decreasing the power consumption.

Does anyone have an idea on how to implement the stain gauge assembly that would not require such (relatively) high current?


texts:
Hello smart people of the internet. Please help me to solve a puzzle. I'm pretty sure there is something simple I'm missing. So here is what I have: I have a 2.2v battery that I want to discharge via R-BAL (see scheme below). I have a MOSFET and a simple switch that controls the gate. There is also a pull-down R2 resistor that keeps the MOSFET closed. Everything works nice here, but the issue that I have is that I want to have my MOSFET to be opened as maximum as possible. To achieve that I need to have Vgs at around 10v.

So, I added a MT3608 DC-DC converter (this one) to my circuit as shown below. Firstly, I do not connect VOUT+ to the gate and measure 10v as shown below. All looks great here.

However, as soon as I connect VOUT+ to the gate, the reading drops back to 2.2v

Here are 2 questions please

Why does it drop back to 2.2v?
I suspect the answer to the first question will be something like "you cannot do that because xxx". Therefore my second question is: is it any way for this circuit to have 10v on gate-source of the MOSFET?


texts: Thermistor scavenge from digital medical thermometer

texts:
To be more specific, there's this thermistor I scavenge from an old medical thermometer.

Something like this

Cut to the chase, I connected my multimeter to the two wire of the thermistor where my multimeter shows a resistance of 40.9 kilo ohm at normal temperature.

Blasting it with the heat of my soldering iron and I got a resistance of 8.8 kilo ohm (I'm really sorry for the bad angle. It's hard holding it here while taking a shot)

When trying to cool it off using my refrigerator, the resistance would become higher than 40.8 kilo ohm.

The question here is, Is there a way to calculate the temperature from the resistance it gave?


texts: How to discover a custom Bluetooth LE device

texts:
I have a custom circuit board which is using a Bluetooth LE chip from Nordic Semiconductor.  I'll be talking to this device with an iOS app and am new to BTLE and somewhat confused by the whole discovery/pairing flow.  Our device simply sends out ASCII text which is a custom data format.

The EE who developed this board hasn't given me a lot of guidance on how to connect to it.  When I use the LightBlue iOS app I can see the device and it's UUIDs.  The UUIDs I see are exactly the same as the UUIDs in the Nordic nRF UART App.

My main questions are:

What UUIDs will my boards need to use?  There will be more than just one board, so it seems like each one will have it's own UUID?
Does my device need to get some "special" UUID from bluetooth.org?

I know there are different UUIDs for both the service and the characteristics...my questions apply to all of these.


texts: I am currently designing a multi-layered PC board and there is situation where signals are referencing the ground plane meant to be used for the 3.3v supply. So, for example. I have a 3.3v plane on L8 with its ground reference on L7, however, there are some 5V signals on L6 which are now referencing the L7 gnd plane. Could anyone please let me know if this could cause any potential failures or EMI issues?


texts: Digital Circuit question - sensing input across power rails using a micro

texts:
In the Circuit shown below, I am trying to achieve the following (I know my circuit is not correct, it is an attempt).

Problem: WHen INPUT_N = 0V, the input to the microcontroller does not go low.

INPUT_N is at 12V when inactive and needs to be sensed using a microcontroller running on 3.3V.

Question: If I remove the Diode, there will be leakage from the 12V rail (i.e. INPUT_N when inactive) to the 3.3V rail right???

What would be a good way to isolate these two?


texts: Microcontroller and design for multiple displays

texts:
at my day job I'm an application level developer, but I have an idea that I would like to prototype thats a bit more on the microcontroller side.
Basically I want to be be able to display some static images on 4 (although the ability to expand would be nice) 2-4 inch color screens such as TFT or OLED. as far as I can tell, displays that have onboard controllers that implement the SPI are ideal. Seems like my limitations there are low refresh rates.. but I can live with around 5 fps. and play a short sound clip on a button press. Not sure what else is out there and really don't want to write my own drivers if I can avoid it.
my big problem is the controller. The ones i've looked into seem to have 1 or 2 sets of dedicated SPI pins. I know SPI is a 1 controller, multiple devices scheme, but that still seems limited by the number of selector pins. I've never designed a project from scratch like this, and I'd love some help getting started. I can barely find examples of people using 2 displays with Raspberry Pis. I'm not sold on Pi or arduino, I'm just fammilliar with them. Any other userfriendly ish MCU would work great.
If theres a better way to connect, or a better microcontroller to use I'd love to know.


texts:
As shown in the photo below, the PCB design was sent for fabrication without the drill data. Is it still possible to drill the via holes so we can save the PCBs?

This is a 2 layer board, most of the traces are on the top, a few are below. Is it practical to send the drill file to a machining shop and have them drill the holes? Will the drill file already specify the holes, or is there a standard hole size which I can let the machining shop know?


texts: Simple Op Amp Non-inverting Amplifier Circuit Not Working

texts:
I am only just starting to learn about circuits and electricity, so please bare with me.

I am attempting to build the circuit pictured below:

And this is my rendition of it:

Here are the parts used:

-Op Amp is the LM318 from TI

-Photodiode is the SFH 213 from Osram

-Power supply is 9 Volts 1 Amp

-My resistance is a bit higher, with 2 1 Megohm resistors

The issue is that I should be seeing a much higher voltage than what I am seeing, I get between .15 V when covered to .23 V when uncovered. From what I understand, the higher Rf is, the higher my voltage should go. But adding more resistors does almost nothing, it slightly increases the values. If I put a 100K ohms instead of a 1 Megohm, I get almost the same values.

I have tried to build every variation of the op amp mathematical functions but not one of them has worked correctly. I've also tried a few different kinds of transimpedance amplifiers to increase my photodiode signal but none of those have worked either. I also have swapped out my photodiode with other photodiodes and my op amp with other op amps. In my attempts I've already blown up a photodiode and an op amp.

I have been successful in building the circuits I want in QUCs simulation software, but none of that has translated to the board.

With all of that in mind, I figure it means that my understanding of ground is wrong, my supply current is much too high for the op amp, or that I don't understand how a breadboard works. But I have watched countless videos and have been working on this for over a week, well over 20 hours trying to get op amps to work the way I would like them to, but have been completely unsuccessful. I don't understand what I am doing differently from every example I have watched and every diagram I have tried to copy.

If you need more information let me know.


texts: Why doesn't smaller Transmission Lines affect Signal Integrity?

texts:
I am reading High Speed Digital Design: A Handbook of Black Magic. It was mentioned that if length of transmission line (Microstrip or stripline) is less than 1/10th of the wavelength of highest frequency component, then transmission line matching is not important. I am trying to visualize the phenomenon which will make matching insignificant for shorter transmission lines. I still think mismatch will cause reflection at the point of mismatch.

Can someone help me in understanding it? I am not sure if my question requires a detailed explanation and may be unsuited as a question over here. If this is the case, then please help me with finding relevant reading sources and some terms to google.


texts: What is the purpose of ADC sampling time?

texts:
I am trying to understand the usage of ADC sampling time?

The ADC I have has a programmable sampling time of 100nsec/500nsec and 1uSec. What is the primary use case of longer sampling time, why wouldn't you use 100nsec for every signal?

[I also hear sometimes the sampling time is called with alternative names. I am interested in the circuits sample and hold time just before the conversion]

Additional question: what happens if the signal is changing in amplitude during sampling time? If it is falling or rising? Would the ADC take the last position of the signal or does it  produce some sort of averaging? If averaging, what is the basis for this, how does it work?

ADC Characteristics:

Capacitor:min 4pF, max:tbd

switch resistance: 1.5K min, 6k max

sampling time: 100nsec, 500nsec (there are longer options but irrelevant)


texts:
I am trying to develop a schematic with minimal components.
The board would drive a N-MOSFET from a microcontroller, and I am wondering if I can omit the gate resistors (pulldown for "default" off, series from microcontroller to gate).
The transistor is essentially charging a capacitor whose charge will be used to provide high current for a very short time (20mA at 3V for 15ms to downstream).
The rationale behind omitting the gate resistors is the following:

4.7kOhm current limiting resistor (VCC from a 3V coin cell, limit high current which reduces coin cell life). This would mean low drain current.
Transistor very close to microcontroller, expected low parasitic noise.

My question is: would this design work?


texts: i am building a charging station for my lipo batteries for my hobby. i have 2 lead acid batteries, 12v@18ah and another 12v@22ah want to couple these in parallel to bump up the the amps. i have heard the facts about charging and discharging batteries with different amps. but my question is will 4amps be that big of a difference? if so i will have to go out and find another battery to match one of the two. thanks for the info


texts:
In EveryCircuit, they have three different voltage sources, one is DC (left), one is AC (middle), and then one is just pulsing (right) --

Is there a formal name for the 'pulsing one-way-current'? Is this used at all in practical applications, or only really in simulators? I was only aware of AC and DC until using these simulations.


texts: Is there a generic software for LED banners?

texts:
I have a scrolling LED banner (16 LED's tall, like those stock tickers), and the software that it comes with is lacking the functions that I need. Is there a more advanced generic software that can send messages to an LED banner?

I would like the software to automatically read an RSS feed and upload messages to the screen.


texts: amplifier quality waveform for different transistors

texts:
I have tested two transistors in multisim, the first is the default(more of generic) and the second is the 2N3904

here is the first picture with default transistor in placed

and here is the corresponding waveform

as you can see, its smooth, but if we use the 2N3904 (available in my local electronic store)

the waveform looks like below

the waveform looks heavily distorted. What should we change in the circuit so that the waveform is the same as the original transistor placed. Thanks

Also, as a side note, what modifications are needed, so that the waveform is not inverted. Thanks


texts: What happens when this integrator circuit reaches saturation?

texts:
I'm trying to understand integrator circuit timing, specifically at the point of op amp saturation. Here's my circuit:

The op amp is dual supply +/-12V. Vin is a square wave varying from -5V to +5V with a 50% duty cycle and period of 40ms - slow enough so that Vout will reach saturation. Here's the simulation output:

Here's my understanding:

At 6ms the op amp reaches negative saturation voltage and can no longer maintain 0V (virtual ground) at its negative input. V(R3) is still 5V so current flows into C1 (it can't flow into the "infinite" impedance op amp input). As charge collects at C1 its voltage increases meaning less current flows through R3.

What is the formula for calculating the time taken for V(R3) to drop to zero? Is it just 5RC  (which is 5ms) and tallies with the simulation or do I have to take into account the fact that there's charge already accumulated on C1 plates due negative voltage at Vout?

Additionally, what happens when Vin changes to -5V (at 21ms). What's the formula for calculating the time taken for V- to reach zero?


texts: Save data on sim card using micro-controller

texts:
SIM cards come in various data capacities, from 8 KB to at least 256 KB. All allow a maximum of 250 contacts to be stored on the SIM,

Is it possible to save data (other then contacts) in sim card, interfacing it with micro-controller then transfer data from micro-controller to sim card?


texts:
I am trying to use a 24V 10A SMPS to supply power to multiple loads. The SMPS has 2 sets of V+ and V- outputs.

I wanted to power a 24V 5A motor connected to the SMPS, as well and use the 2nd output from the SMPS with a buck converter and power a 12V 8A load also.

I thought that in theory this works because the math all adds up, what I can't understand (I'm very new to electronics) is: Will the buck just use around the 24V 5A and turn it to 12V 5A or will it try to convert all the 24V 10A leaving the 1st load underpowered?


texts: What are the components needed for this receiver?

texts:
I want to build a simple crystal radio receiver. I do not want amplify the signal received. I want to detect the presence of a transmitted signal, and then use the presence of the received signal as a trigger to switch on another device (battery powered).
My knowledge is VERY basic, and I have been trying to learn more. I have found a schematic on the web.

http://www.circuitdiagram.org/how-to-make-build-crystal-radio.html

Is this design suitable for my intended purpose? (minus the Earpiece)
From what I can tell, this receiver is made up of an inductor, a variable capacitor, and a diode. I am assuming my circuit would need a transistor switch as well. What else would I need? (I have assumed here that the antenna is part of the inductor coil - is that correct?)

I am looking for components I can use to make up this circuit.
I want to receive the signal across a range of 60 feet and I want the circuit to be small (>1cm). What else do I have to ascertain in order to start searching for the components I need?

If anyone can to suggest suitable inductors, capacitors and/or diodes - this novice would be grateful!


texts: Where should power factor correction and active harmonic filter connected?

texts:
After mains electricity meter, there is an isolation transformer (delta to star) and all load is connected to the secondary of the isolation transformer.

We plan to install a power factor correction device and an active harmonic filter. Our load is unbalanced (lots of single phase split AC that gets turned on and off as per use) and active harmonic filter should be able to balance the load as well.

Our concern is that if connected to the primary, it might not be able to balance the load (since neutral is not even connected to isolation transformer's primary side) and if we connect this to secondary it won't be able to correct power factor as necessary since it won't be able to compensate isolation transformer losses

Should we connect it to the primary of isolation transformer or at secondary of the transformer?

Update 1


texts:
My Engineering Design and Development (EDD) class is working on a high altitude balloon (HAB) and my friend an I are in charge of data collection. It looks like we are going to use an Arduino (Uno or Due based on needed ports) and sensor breakout boards for logging data. As I was browsing our possibilities, and I wasn't quite sure if running multiple I2C devices on the Arduino was realistic.

For example, in viewing the tutorials for an accelerometer (3-axis) and a gyroscope (3-axis), I found that both require the use of the SDA and SCL ports on the Arduino. If I have read correctly, each device has a different I2C address, and you can use them in the same port, but I wasn't sure. If that is possible, how do you know what the address is or how to assign the address? Is there a maximum limit of I2C devices that an Arduino can handle? I have reviewed  How to connect multiple i2c-interface devices into a single pin A4 (SDA) and A5 (SCL) on Arduino? but I'm not quite sure this answers my questions fully.


texts: What are the differences between a car battery and other smaller batteries?

texts: I'm not understanding why there's a small 9V battery while a giant car battery is only 12V.  Is a car battery 12V b/c it's enough to supply the whole car while getting recharged for prolonged time or is there a different reason why a car battery is 12V?


texts: Simple way to charge 5 x AA via USB - any off-the-shelf component for that?

texts:
I need to power a gadget I am building with 5 x AA batteries (6V), but I also want to be able to recharge it via USB (5V) while the gadget is on (that is, I want to be able to plug and unplug the USB cord freely, without the need to remove the battery or turn the device off).

I have read a lot already about this, but there seem to be so many options to choose from that I am rather confused.

So the core of my question is:

  Is there any well-known off-the-shelf component or IC to boost 5V from USB to (more than) 6V so I can charge the pack?

As an example of what I understand as "well known off the shelf component", I could mention "4017" as counter, "555" as timer/oscillator, "7806" as voltage regulator, etc. It's something I could find and use easily and cheaply.


texts:
I have the following : Metallized film capacitor. I read in some papers that MFC are protected against short-circuit with a self healing.
Self-healing is a phenomenon where  in the event the electrodes are  exposed to each other instead of the capacitor shorting, the capacitor repairs itself.  This repairing of the capacitor is due to the thinness of the foils used.
In a film /foil  capacitor when the foils are exposed to each other, the foils would touch and short  together rendering the capacitor useless.
When a capacitor with metalized films has the foils exposed to each other, they  also will touch each other, but here the combination of the foils thinness and the high  energy  density  at the fault area causes the foils to vaporize and the capacitor stays in operation.
My question:
In case of failure one foil is sucked to other foils the energy density is dissipated on large fault area which leads to not vaporize of the foils in contact and failure of the self-healing process. So short circuit of the MFC is possible, someone can confirm this through an experience with failure of MFC ?


texts: Define this music-related terms with electrical terms

texts:
I have a somewhat bizarre question, I don't really understand this musical concepts and I think that some Electrical engineering could help in this case, especially with the analytic phase.

Assuming that you are considering the music as an electric signal, and you have to define the properties and the values that this hypothetical electrical signals must offer :

what is an harmonics ? For example when you play a single note on a piano and you press 1 key, the other keys/strings around that key vibrate and create something that you hear as 1 single note but in reality it's something composed of multiple harmonics. What is the parallel that works in Electrical engineering ?
what is an Accordion ?
also if you have a note that is standardized and defined to be at X Hz, this means that you have X bandwidth ? What goes and fits in that bandwidth ? It means that if a note plays at 50Hz from a string I can get noise and additional harmonics from 0 to 50Hz only from that string ? This is like having an engine producing AC at 50Hz that can spike sometimes or that needs to "clean" its own output ?

According to my intentions I would like to compare this concepts to something practical and maybe some working components like a transformer, a resistance, a capacitor, use whatever you want that fits the explanation.

I would like to know how things look like, what properties are expressed and in case of diagrams and pictures what is the domain on the x axis and the domain on the y.


texts: Arduino pin 13 dead - does that mean replacement board is dead?

texts:
I have purchased an Arduino Uno R3 and when I was working with my project, by mistake some wire went to the board and connected R3 pin with itself (connects pins of the LED). Then pin 13 LED fired and after that, all pins became dead. When I upload, RX and RT LEDs blink like usual, but all other pins don't work. I have uploaded a program with all pins set as output but none work.

Does that mean my board is dead? How do I check if my board is dead?


texts: How do people estimate node voltage and branch current by observing a circuit?

texts:
The question might sound silly, but I hope experts can guide me on that particular issue. I am struggling for the last few months. I am a beginner in analog circuit design. When I follow a tutorial, I found that by observing a big transistor (MOS)-level circuit, they can say about node voltages, branch current, input and output resistance, and sometimes gain. My question is, without drawing a small-signal model of those circuits, how do people do that? Is this because they already solved many circuits by hand (I mean not using any simulator), and that is why a concept was built? Even when I try to draw a small-signal model for a big circuit I get lost due to the circuit's complexity. What is a good way to approach this kind of circuit?
I added the figure as an example circuit!
Thanks for your time!
Figure reference: https://www.hindawi.com/journals/apec/2014/274795/


texts:
On a number of projects I'm building, there's a transformer between wall power and device power. In the parts lists, the transformers are usually designated by "12v secondary transformer" or "18v 4a Secondary Transformer".

Because the flow goes from wall power through the transformer and then to a rectifier, I assume that it's just converting 120V AC to whatever DC, stabilizing it a bit with the rectifier.

Is that a safe assumption? Instead of finding an actual transformer, can I just substitute, say an 18V 4a laptop power supply or 12v wall wart I have lying about, using that for my power input to the rectifier? Why or why not?

Or is there something more to a "secondary" transformer?


texts: capacitor voltage ripple in buck converter

texts:
I am struggling with output voltage ripple calculation of the buck converter below. Firstly, I don't understand the following statement from the lecture.    Can anyone explain it?

  If the capacitor voltage ripple is small, then essentially all of the
  ac component of inductor current flows through the capacitor.

The images are from the lecture here (pages 39-40).


texts: EMC CISPR 14 conducted emissions terminals

texts:
I'm trying to improve my understanding of the CISPR 14.1 EMC test procedures and requirements, with a view to performing precompliance testing. In particular, I'm looking at conducted emissions measurements.
My understanding is that conducted emissions measurements are applied only to mains cables, but reading CISPR 14.1 I'm unable to confirm that this is the case.
Measurements in the 150kHz to 30MHz range are made on terminals:

Terminals are defined as conductive parts, suitable for re-usable electrical connection to external circuits

which I understand to also refers to connectors, not just terminal blocks.
There are additional stipulations as to which terminals the limits apply to, which in addition to the obvious mains supply terminals are:

On additional terminals of appliances as well as on load and additional terminals of regulating controls incorporating semiconductor devices the relaxed limits given for "additional terminals" in columns 4 and 5 apply.
No terminal voltage limits apply for leads, which are not easily extensible by the user (permanently connected, or provided with a specific connector), which are shorter than 2 m, and which connect the equipment with an auxiliary apparatus or device, (e.g. semiconductor speed controls, power plugs with AC-DC converters).

Our device has a 12VDC solenoid mounted externally, connected by a specific connector and 1.5m length of cable, but I don't think that the solenoid would be classified as an "auxiliary apparatus", which would indicate that it would require testing. Edit: here's a block diagram/simplified schematic. There are some electronics running off the 12VDC too which control the relays.

I've searched for other CISPR 14.1 test reports to compare to but none that I can find have any more terminals than just the power supply.
So what terminals/connections/cables does one actually apply conducted emissions testing to?


texts:
Sounds like a stupid question, but really hasn't been asked before, or I haven't found a post about it. Either way, here it is:

I bought a soldering iron recently and am looking for a place in my house to do my soldering. Of course the first thing in my mind would be to solder in the basement or garage and as close to a window/outdoors with good circulation, however I plan on working with arduino boards and would like to everything in my upstairs "computer room" near my gadgets. Do you think opening up my window in my room and having a fan suck out the fumes aimed at the window would be suffice to be safe, or should I stick with the basement/garage idea. Let me know on your thoughts.


texts: Can I power an interactive 'live' wall with copper tape and a 15v ac adapter?

texts:
I'm working on a class project to make a living wall with LEDs, paint, and copper tape spiral magnet speakers. I have a 15v ac adapter to power the wall and copper tape to connect the LEDs in parallel groups of series circuits.

If you managed to understand any of that, I'm wondering if the coper tape (carrying the current) will be dangerous for people to touch? The 15v adapter actually is producing 19v dc and according to the label, has 900mA current.


texts:
Bit of a newb with electronics, so if this question has an obvious answer, please excuse me.

I am trying to attach an electronic drum pad to the Vin input of an ADC0820 flash ADC. I am powering it with 5 V and using a 3.3 V reference voltage (the voltage ref is a differential input on this IC, with a VREF- of 0 V.) When I attach a 10 k pot to the ADC VIN input, everything works as expected.

Here's the thing that's confusing me: when I hook up a scope and read the drum pad when it's not attached to the ADC, it reads at 0 V when not being hit. However, when I attach it to the VIN input this level rises to 0.1 V and causes the ADC to read above 0. It seems the VIN pin is charged from the VREF+ pin and this is being sent back down the drum pad. I have confirmed this by connecting a pot to the VREF+ pin and turning it up and down - the charge leaving the VIN pin changes! This doesn't happen when I experiment with different ADC chips. Why is it happening here?


texts: How to edit the shape of pads for a component footprint in Fusion 360?

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Using Fusion 360, I'm attempting to create a PCB component that has irregularly shaped pads (see image). The 45deg pads in each corner are essential, otherwise the nets will short.
In my electronics library, I have successfully created a package using the 3d package generator. I then switch to the footprint view, but for the life of me cannot figure out how to modify the shape of the corner pads.
How can I modify the shape of these pads?


texts: Pass line level signal through electric guitar

texts:
I have an idea for a project where I want to pass a line level signal through my electric guitar.

The idea is to have a 3.5mm jack input on my guitar, to which I can input a line level signal. Then I want this signal to go through the guitar lead and into my amp. I also need to be able to play guitar at the same time, so this signal also needs to go to the amp.

My initial concerns are that the line level signal will be far too hot for the amp, and that also the signal might interfere with the pickups, so may need to be isolated somehow (sorry, it's been many years since I dabbled in electronics).

Also, I realise that this will sound terrible - this isn't so I can jam along with my iPhone, its for some specific weird effects.