texts:
I found this simple FM transmitter circuit:

I built it an it works rather nicely. There are many simple FM transmitter circuits on Google, most of which look basically like this:

These work by modulating the base-collector capacitance of the BJT using the sound signal, which appears in parallel with the L1-VC1 resonant circuit, whose frequency changes with the capacitance.

The one I built however seems different (the top one):

1) There the Rf OUT is taken from the emitter of the BJT, while in the ones resembling the bottom picture, output is taken from the collector. The circuit on the bottom Picture is operating in common-base mode, so taking the output from the collector makes sense. But what amplifier configuration is used in the first Picture? Only time I know when the output is taken from the emitter is the common collector configuration, but that one has no voltage amplification so it seems strange that it would be used here.

2) In the bottom one, C1 and C3 are huge capacitors for the high frequency RF signal, and therefore in essence short the base of the BJT to supply, and so the base-collector capacitance appears in parallel to L1 and VC1. But what is happening in the top circuit? My quess is that C3 in the top one does the same as C3 in the bottom one, as it sits parallel to the battery (one side grounded, one side to +9V). But in the top one, we have C4 connected to ground from the collector, instead of being connected in parallel to L1. Which components form the resonant circuit in the top circuit?

Thank you!


texts: Is it possible that a load can be destroyed if I am disconnecting all other loads in the circuit but one?

texts:
I consider myself as a beginner, so please don't be that hard to me.

Can I theoreticaly destroy a unfused load if I disconnect all loads but one in the same circuit? In my understanding the current which would normally spread to all these loads would then only flow through the remaining loads which is still connected and could destroy it because it was not build for such high current?

For example: I bought a scooter. If you disconnect the rear blinkers, then the front blinkers are way faster, so I think it is because more current is flowing through it.

So if I disconnect the ECU (36) in the following circuit then I guess the current is very high on the remaining components.

I thought the fuses would blow in this case, but I had the case were the plastic of the fuses was just melting but the fuses stayed alive after I had a shortcircuit, almost all loads were disconnected at that time.

This is the circuit:

LEGEND FOR SWITCH PANEL - SR 50 PUREJET
1) multiple plug
2) dipped beam / high beam relay
3) Oil level switch
4) Fuel level sensor
5) Cockpit (matrix)
6) Immobilizer antenna
7) Ignition key switch
8) Horn
9) Left light switch
10) Rear brake light switch (on left
Switch)
11) Right light switch
12) Front brake light switch (on
right switch)
13) Rear turn signal, left
14) Tail light
15) Double light bulb for stand
/ Brake light
16) Rear turn signal, right
17) License plate lighting (only at
Versions USA / CH)
18) Pick up
19) generator
20) Voltage regulator
21) injection relay
22) Starting relay (fault protection)
23) starter motor
24) Battery
25) fuses
26) Fuel pump
27) Air nozzle
28) Fuel Injector
29) Pressure sensor (or in the control unit
integrated)
30) Cylinder head temperature switch
31) HS coil
32) spark plug
33) Gas control sensor
34) Serial connection (Diag.) 35) Oil pump
36) ECU control unit
37) Speed sensor
38) Front turn signal, right
39) Front parking lights (only at
Versions USA / CH)
40) low beam
41) high beam
42) Front turn signal, left
43) headlights
44) diode
45) -
46) -
47) -
48) -
49) -
CABLE COLORS
Ar Orange
Az light blue
B blue
Bi white
G yellow
Gr Gray
M brown
N black
R red
V green
Vi Viola
Ro Rosa


texts: Figuring out battery life from amp draw?

texts:
I decided to take apart one of those cheap handheld fans. It takes 2AA Alkaline batteries. I wanted to hook it up to an arduino as a way to get into electronics, and I wanted to know what kind of battery would be best for the setup.

Hopefully, I measured the amps correctly, and it read out ~.70 when the multimeter was set to 10 and @ DC current. So, the device has a 7A draw. From wikipedia, Alkaline batteries have about ~1800mAh, so 2AA would give 3600mAh.

So, total battery hours from 2AA would be 3600mAh/7000A = .514... which ends up being only half an hour.

If I wanted the setup that lasted roughly 2 hours, then that means I would need at least a 14000mhA battery without considering the arduino amp draw. That means I need at least 1 D battery or 8 AA batteries.

Does that seem right?


texts: PCB design: the setting of the test point and the use of variable resistor

texts:
I am designing a PCB circuit and meeting two problems:

My design includes a two-stage MFB band pass filter. To make sure the center frequency of the filters is the same, I need to add a variable resistor to adjust the center frequency. However, the design is for commercial production. Would it be not so good or not so professional to use the variable resistor? If so, maybe I should try to use some high-precision passive components.

To manually test the performance of the band pass filter mentioned above, I would like to add a test point at the output and use a oscilloscope to see the frequency domain plot. My question is what kind of test point is proper if the design is for production? A flat pad? A via or the TP below.(I have both spring tips and j-hook probes)

Does anyone have any idea or any suggestion?


texts:
I've been working through a proof but I'm stuck on one of the last steps. Consider an inverting op amp with a feedback resistor \$R_f\$ in series with a capacitor and resistor \$R_1\$

simulate this circuit – Schematic created using CircuitLab

I must prove that: $$ \frac {|V_o|}{|V_i|} = \frac {R_f}{R_1} \frac {1}{\sqrt{1+\frac{f_1^2}{f^2}}} $$

My steps so far:
$$ \frac {V_o}{V_i} = \frac {R_f}{R_1 - \frac {j}{\omega C}}$$
$$   = \frac {1}{\frac{R_1}{R_f} - \frac{j}{\omega RC}} $$
$$=\frac{1}{\frac{R_1}{R_f}-j\frac{\omega_c}{\omega}}$$
$$=\frac{1}{\frac{R_1}{R_f}-j\frac{f_c}{f}}$$
Now, how would I go about bringing the resistances out? (a little rusty on my algebra haha)

Thanks!


texts:
Does Orcad Capture enable using variables to specify values that depends on the environment?

For example, I have many pages in my project, and each page/sheet contains a text that says "sheet number X out of Y".
It should be like so: Sheet number $SHEET_NUMBER out of  $TOTAL_SHEETS


texts: How can I avoid mixing up pins or mirroring pinouts on pin header connectors?

texts:
A chronic problem for me when laying out PCBs is pinout mixups on header connectors -- sometimes I will inadvertently interchange adjacent pins or hook pins to things that seem right but aren't, at others I will mirror or rotate the connector altogether from its expected mating orientation.  While debugging tools with flylead cables (my FTDI cable and Bus Pirate both have this) or female-terminated jumper wires can be quite helpful when working around this when prototyping, they're quite a chore to use compared to the correct mating connector, and not always possible now that some things (ARM Cortex-M JTAG/SWD, most notably) are migrating to 50mil header pitch from 100mil.  Building one-off adapters is also a hassle, and the extra mounting height an adapter imposes is sometimes undesirable from a mechanical standpoint as well.

How can I prevent these problems at the design stage -- especially rotated/mirrored pinouts, as they seem to be a bigger problem for me than swapped pins?  Also, are there design strategies I can use to reduce the impact of this class of problems in terms of rework/adaptation effort needed?  I am doing schematic capture here -- I've had this problem when working both with gEDA in the past and currently with KiCAD.  DRC and netlisting aren't able to catch these issues because I'm dealing with generic pins on the header side, and sometimes on the "other end" (i.e. the component the connector is wired to) as well -- and these problems are occurring in schematic capture -- not necessarily at actual layout time.


texts:
I have designed a micro controller circuit to actuate a DC motor using signals from an ATmega234P chip via a L239DNE H-Bridge. The problem I am having is that the motor runs slower than usual while executing the PWM code. As soon as I connect an MKII programmer to the ISP the motor works properly. Attached are my circuit schematics and the code that I am running. Any help would be very much appreciated!

Code (source):

/*
 * DCM_PWM.c
 *
 * Created: 14/09/2018 6:31:42 PM
 * Author : s4354441
 */

#define F_CPU 1000000UL
#include <avr/io.h>
#include <util/delay.h>

void setup_timer0 (void)
{
  DDRB = (1<<DDB3) | (1<<DDB4); // set the PWM pin to output.
  TCCR0A = (1<<COM0A1) | (1<<COM0A0) | (1<<COM0B1) | (1<<COM0B0) | (0<WGM01) | (1<<WGM00); // toggle OC0A on compare match
  TCCR0B = (0<<WGM02) | (0<<CS02)| (0<<CS01) | (1<<CS00); //select PWM, Phase Correct
  OCR0A = 0; // set output compare value
  OCR0B = 0; // set output compare value
}

void PWM_func (void)
{
  for (int i=0; i<255; i++) {
    OCR0A = i;
    _delay_ms(25);
  }

  for (int i=255; i>0; i--) {
    OCR0A = i;
    _delay_ms(10);
  }

  for (int i=0; i<255; i++) {
    OCR0B = i;
    _delay_ms(5);
  }

  for (int i=255; i>0; i--) {
    OCR0B = i;
    _delay_ms(25);
  }

  for (int i=0; i<255; i++) {
    OCR0A = i;
    _delay_ms(10);
  }
}

int main (void)
{
  setup_timer0();
  PWM_func();
}

PCB Schematic 1:

PCB Schematic 2:


texts: Common Mode Noise on Differential Lines Driven Against Chassis GND

texts:
How is common mode noise filtered on differential lines that have a noise source that is driving them relative to chassis GND? I drew a picture of what I am imagining below. Imagine a PCB with differential signals that are in a metal enclosure.

I think the common mode noise will drive the entire circuit with a current shown in purple below:

All the documentation I find show single ended examples like the one in reference image 1 below, where a choke is used between the signal line and system GND to reject the common mode. There are also examples like reference image 2 below where a choke is used to reject common mode between two differential lines (say from a skew mismatch of the transmission lines).

To deal with this do I need to use 3 common mode chokes? One between the two differential signals, and then on each differential signal and ground? Advice is appreciated.

Choke 1: N and P signal

Choke 2: N signal and system GND

Choke 3: P signal and system GND

REFERENCE IMAGE 1: Choke on single-ended signal and system GND.

Image Source

REFERENCE IMAGE 2: Choke on differential signals.

Image Source


texts:
i need your help to solve this simple circuit using Thevenin, i used Ohm to solve but using thevenin the values was diferent, so i need your help, the question is the voltage at R4 and the current at R6, thanks a lot.

I do this:


texts: How to find the time delay of second order system from process transient

texts:
I am seeking for simple Identification method for the second-order systems plus time delay.

The system is QNET vertical take-off and landing (VTOL) trainer. Using the tutorial I found the system parameters.

The only thing I need to know is how to measure is the time delay ( the Transport
Delay in the figure )

Simulation step response without time delay

Real system Time domain response

the question is : How I could find the dead time from the experiment data (process transient) ?


texts:
"Optimal approach to relaying occurs when transmission is recieved simultaneously at the destination and relay." Is this still valid in the light of recent research? Are there trade-offs involved?

This question is motivated by the statement in (DOI:10.1109/VETECF.2002.1040432) where the author stated in the introduction that " The reason for this is that in traditional relaying, packets are only relayed through a single path. However, the optimal method of relaying [2] uses a different approach: the transmission is received simultaneously at the destination and relay"

[2] Cover, T., & Gamal, A. E. (1979). Capacity theorems for the relay channel. IEEE Transactions on information theory, 25(5), 572-584.


texts: determine motor amp draw before purchase

texts: I am trying to buy a geared DC motor from a large, international auction site.  However, most listings do not list the amp draw.  The vast majority explain the motor like "12V 30rpm 25mm DC Gear Motor Micro DC Gear Box Motor" or the like. My motor controller lists as the maximum power it can handle is 12v by 2 amps.  Is it possible to determine if the motor controller can successfully handle a motor if I only have access to the voltage, rpm and size?


texts: Using a 1.5V battery to increase the voltage from a headphone jack so it can switch a transistor at lower volumes

texts:
I recently built a circuit using a 2N3904 BJT transistor with the hopes that when connected to a headphone jack, it would light a LED whenever an audio signal was passed through.  However, I found that this only worked when I put my devices to full volume (or at least > 80%).  Trying a Darlington transistor setup didn't help.  I need this LED to activate at much lower volumes (this is for a research project in which I need a visual indication that a sound is playing, often at 50% volume).  My proposed solution:

Add a 1.5V battery and resistor to the Audio line in before the transistor base so the battery will amplify the baseline voltage enough that it will trigger at lower volumes.  Then I could just use the appropriate resistor to adjust the voltage amplification of the signal for different sounds I'm using.

Before I try this, I thought I'd post on here and get some second opinions.  My two questions are:

-Will this work to amplify the voltage of the audio signal as I'm intending?

-If so, will I run into any risk of damaging any headphone jacks which are plugged into this?

On the image, the ground and empty negative terminal of the battery at the top are connected to the ground and Left audio channel of the headphone cable, respectively.  Any advice is greatly appreciated!

This is similar to the question posted here: How can I effectively reduce the voltage needed to activate a transistor?
But since I'm a beginner, I'm looking for easier ways to amplify the signal.  This "just has to work" without being fancy.


texts: What is minimum trace width for "advanced" fab shops and what are possible manufacturing/reliability issues?

texts:
One of fab houses suggested stackup with 2mil traces.  Given that this is their stackup so they must be feeling comfortable with it and SI performance aside - are there any reliability/manufacturability issues that arise at such narrow geometry?  I can think that maintaining consistent width (thus impedance) might be more challenging due to relative error being higher.

Any thoughts?


texts: What type of switch is only on when released

texts: I have a situation where I've got a few electronics boards stacked on top of each other. I don't want the boards to be powered when stacked but when they're no longer on top of one another I want them to turn on. I figure a push switch that is off while depressed but on when compressed makes sense to me, is there a specific name for this type of switch?


texts: Specman UVM: What is the difference between write_reg { .field == 2;}; and write_reg_fields?

texts:
I'm working with vr_ad package for e. My question is:
What is the difference between 2 following macros for modifying registers (suppose foo register consists of 2 fields field1 and field2):

1)

write_reg foo {.field1 == 1;};

2)

write_reg_fields foo {.field1 = 1};

I really appreciate any help


texts: What kind of monophasic induction motor is this?

texts:
About 15 Years ago I bought an induction motor from a junk yard. It have 6 leads being that 2 are the same lead, so 5.

The guy who sold me had no idea from what machine it came. And I don't quite remember what I did to make it work, I was 10 yo, maybe I just tried at random. But it had a very good torque for its size (about 8 cm in diameter and 12 cm long) and rotated about 800-1100 rpm, probably the strongest motor I have. It worked using a single running capacitor.

But I always noted it heated to much, and specifically one of the sides of it. I disassembled it, analysed the windings and also measured the DC resistance between the windings to check how it was. And what I've seen doesn't seem familiar. This is how it is:

I hope the image isn't confusing. Windings 1 and 2 are in series internally, as well as windings 3,4,5 and 6. But there was, according to my measurements, a 15 ohm fault between the white wire and the black wire. Being there is no physical connection between them.

Windings 1,2,3 and 4 are about 20-22 ohm in DC resistance each, while the windings 5 and 6 the double of that.

The way it was working was by connecting one phase to Yellow + Gray, a 45 uF capacitor from that phase to the white wire, and the other phase to the black wire.

Now, that only worked because of the said fault. Otherwise only the windings  1 and 2 would be energized. But the fault, which I found to be in the middle of winding 5, made winding 3 and 4 get energized, but also being greatly bypassed by the capacitor (which is in parallel with 3 and 4) and causing that segment of winding 5 to get extremely hot.

However, it still caused the motor to work well, and the greatest the capacitance the greatest the torque. Also made winding 5 heat like hell.

I don't quite understand why the rotation was low yet, because it still behave mostly as a single pole motor in that context. I think all of that conferred a strange torque curve to it.

But recently the winding 5 took on fire, and with that the said fault had a great increase in resistance. The motor stopped working.

For what I've seen, there's no need to restore this winding, but neither will it behave the same again if I actually wire it as a single pole motor with two auxiliary windings. It will now rotate at 3600 RPM.

So, instead, I want to restore it to it's full glory, in the way I can get the greatest efficency out of it. But I don't know how it's supposed to be used. And that's my question:

How is this motor supposed to be used?

I have never found any schematic for a motor like this one, and I don't know how it's supposed to work.

Thanks!


texts: Can any Op-Amp be used as a voltage follower(buffer)?

texts:
I have a square wave, to which I have to add a buffer. The Frequency of the square wave is around 10MHz. I am new to Op-Amps, but I have read that I need a high slew rate.

Can I use any Op-Amp(with a high slew rate) as my buffer?

Thanks in advance.


texts: Is it possible to interrupt the copy process of a struct by an interrupt in embedded C?

texts:
Inside the driver I have got a function to copy the data from the internal struct into a struct from the application.

Can this process be interrupted by a microcontroller interrupt trigger?

uint16_t getRawData(struct Data *Data_external)
{
  if(Data_external == NULL)
  {
    return ERR_PARA;
  }
  else
  {
    *Data_external = Data_internal;            // the copy process. Could this be interrupted?
  }
  return ERR_NONE;
}


texts: Problem simulating LMP8645 current sense amplfiier in LTspice

texts:
Basically the problem i am getting is that the output offset voltage is extremely large (58mv)

here is the datasheet for the amp: http://www.ti.com/lit/ds/symlink/lmp8645hv.pdf

on page 9 it shows the relation ship between the Vout and Vsense and as you can see the output offset voltage is ~1mV

here is my schematic + simulation :

the blue line is the output voltage Vout, green line is the voltage across R1 (the sense resistor), the x axis is the voltage of V2.

I expect the blue and green lines to match since the gain is set to 1 but as you can see there is a large difference between them which doesnt match the datasheet.

I should note that the circuit behaves as expected when VR1 becomes large, as can be seen here:

I tried a variety of supply voltages too, including +-5, +-2, 5 to GND, 10 to GND, 4 to GND , as well as a variety of gain resistors like 5k, 10k, 20k, and i get the same results.

the spice model was gotten from this page : http://www.ti.com/product/LMP8645/toolssoftware

What am i doing wrong?


texts: RLC Response (Overdamped, Underdamped, and Critically damped)

texts:
Ive got a question about identifying the overdamped, underdamped, and critically damped waveforms of an RLC circuit.

From my (very basic understanding), underdamped decays while oscillating. Critically damped decays the fastest without oscillating, and the overdamped decays without oscillating (but critically damped decreases faster)

In the question below, I feel like the the graph the key shows as overdamped is the critically damped response since it decays the fastest. Which is correct?


texts: Is it bad to have too little or too much resistance?

texts:
OK I need a 27kOhm resistor and I don't like shopping online.
So, I was just wondering if it is bad to have a resistor with a too high or too low value.  I was at Radioshack and all they had was 22kOhm and 33kOhm, but not 27kOhm.

I am building an FM transmitter that calls for a 27kOhm, but I really don't want to order online.

So, can you please tell me if a different value would be OK or if I can use the available value resistors in some way.

The transmitter I am building is this one:

http://i1.wp.com/cdn.makezine.com/uploads/2013/10/kogawa_simplest_transmitter.png?zoom=3&resize=620%2C354

Diagram:


texts: How to design PoE splitter for Mode A and B

texts:
I would like to power my device via PoE, but I do not know which mode (A or B) is provided by the 802.3af power sourcing equipment (PSE). How should I design a splitter to accept both implementations:

A) the phantom power technique common with "endspan" PSEs

B) using "spare" pairs in 10BASE-T and 100BASE-TX as in a "midspan" PSE

I understand that I cannot simply connect pairs 2 and 3 for DC supply in Mode A, as I would need connections to some kind of transformer center-taps and a diode bridge, but then how would that be compatible with Mode B? This is where I need guidance.


texts: What is and how to measure the tuning port capacitance of a VCO

texts:
I was asked to check all the specifications of this Voltage Controlled Oscillator. I might have an idea of how to measure all the parameters except for one, the Tunning Port Capacitance. I think my problem stems from the fact that I don't really know what this parameter means for a VCO. At first, I thought it was kind of an input (or output) capacity, but this seems wrong.

What does this parameter mean for a VCO and how to measure it?


texts: What does the inside of a large lithium ion battery look like?

texts:
I'm a writer and currently working on a young adult Sci-Fi novel so I obviously don't belong on this stack exchange site. If this question isn't allowed here let me know.
I know that inside of a Li-Ion battery there is an anode, a cathode and a separator. There's probably much more than that involved but those are the elements I'm interested in. Basically I'm just wondering what a larger lithium ion battery looks like (like large enough to power a vehicle.) Is it possible to safely open a lithium ion battery? If so, what would you see looking into it?
I can google what the inside of a lithium ion battery looks like but all I can find is diagrams which is helpful but I don't know what an anode or a cathode or a separator look like in real life. What does an anode look like? What does a cathode look like? What does a separator look like? Are these types of things even things that you can see?
This is only small part of my novel which is why I'm asking rather than taking the time to research thoroughly but I want to make sure my writing is as accurate as possible.
Edit
What causes a lithium ion cell to short circuit, overheat, and/or explode? I get that it occurs often when the separator breaks down and allows the anode and cathode to touch but what causes the separator to break down?


texts:
I know nothing about motors. I have DC motor (sealed in a casing) that uses 6v/12v 1a (mains switching power supply) with 2.1x5.5mm DC connector. It has variable speed controller, reversible direction, and can operate at between around 5-100rpm.

The only available spec states it can be used with powersources of 6v to 12v. Presumably too high a current could damage it though?

I've used it safely with P9 batteries but they go flat too quickly.

What batteries do you think it's safe to use this with? car batteries? Lawnmower batteries?


texts:
Hello so I thought I could use a VCO to generate a sine wave , but I didn't find anything that generates a sine wave with 500Khz. So then thought to use a microcontroller, like Atmel o Arduino, but it's really difficult to create a PWM greater than 4MHz. Anyway so now I am at a loss.
Does anyone know of any ways to make a sine wave? Please let me know what you think please.


texts: How does this automatic emergency LED work?

texts:
This circuit is very popular on the Internet. I understand it but I have a question about the PNP transistor. The base of the transistor is connected directly to the regulated output of the transformer, so when the transformer produces 9 volts the base voltage will be greater than or equal to the emitter voltage and the transistor will open the circuit.

That's OK. But when there is no power in the transformer, the output of the transformer is floating and the transistor's base as well. I tried to find a path that connects any negative voltage to the base so that it closes the circuit and the LEDs turn on but I didn't find one!

Would you tell me from where the transistor's base gets its negative voltage? Or at least a voltage that is less than the emitter voltage by 0.7 volts?


texts: SPI bus termination and pull-up resistors

texts:
My microcontroller (ATMEL series) needs to communicate to a slave device using SPI protocol. I am designing the hardware. The maximum SPI bus speed is 1 MHz. The distance between the master and slave is less than 50mm.

Q1) Do I need to add termination in series on the SPI bus to avoid reflection at this SPI speed (1MHz)? If so, how should I calculate its value and where should I put the termination resistor - near the master or near the slave?

Q2) I have seen other reference designs where sometimes people use pull-up resistors on all SPI signals, sometime only on a few signals (CS or MISO) and sometimes none. Do we need pull-up resistors on SPI signals (since the SPI port is push-pull configuration)? The only time pins will be floating is until the microcontroller get its power and can set pins as outputs. So should I need to use pull-up resistors or what will happen if I don't use any pull-up resistors in my design?


texts: Changing a signal's DC offset before amplifiter and ADC

texts:
I'm trying to feed an audio signal which has around 5v DC bias to an amplifier and then an ADC. the final signal should have 2.5v DC bias. i've mixed things i've learned off forums but i'm still not getting the desired result. i don't have an oscilloscope to check but when the samples are played back in android, the volume is too low so i'm guessing the DC bias is not set up correctly.

any input is appreciated

the output from stage 1 is biased at exactly 2.5v while the final output is biased at 3.68Volt!

EDITS

C8 is 1uF in the actual soldered circuit
the output from stage 1 is biased at exactly 2.5v while the final output is biased at 3.68Volt!


texts:
I have made a small breakout board with the QN9021 SOC (BLE + ARM Cortex M0). I am having trouble flashing the code into this device. Assuming that this device is wired properly and working fine, how do I program it?
None of the cheap OpenOCD debuggers seem to support it! and the commercial (JLink/ULink) are too costly for me.
Can I still use the unsupported debuggers somehow (mayne by manually adding the memory location map)? If so kindly tell me how to do so?


texts: How data movement from large register to small register works in VHDL?

texts: I went through a VHDL sample code for memory management. In that data from a 32 bit register was directly moved into a 8 bit register. My doubt it is how this data movement can happen? Is there is any default condition for VHDL for such data transfer?


texts: Do I need a ground polygon for analog design?

texts: I have an analog circuit with few opamps (max freq. 500Hz) and a DC-DC converter with 500 kHz frequency for power supply. It seems I need to use both sides of PCB for components and routing if I use 2 layers. Or, I can go for 4 layers with dedicated power and ground plane. I see in most cases dedicated planes are used, or at least one side is used for ground. Do I need a good ground plane in my case? Or would it be sufficient if I use thick trace for power and ground?


texts: Why is "GaN tech" so revolutionary for wall chargers?

texts:
A big selling point of RAVPower wall chargers is that they use "GaN tech."

I assume that's gallium nitride but, anyway, my question is:  If that's what their chargers use what do most other wall chargers use? Silicon?

How do they use it?

This picture from the Wikipedia page on "AC adapters shows the various parts of a wall charger.

I wouldn't think GaN would be used in the transformer. Rather, I think that those would use copper wire coiled around it, etc.


texts:
I have found this small signal analysis circuit in my exercise.

simulate this circuit – Schematic created using CircuitLab

I tried both \$\pi\$-model and T-model but can't go anywhere. When trying to figure out \$V_o\$ can't decide whether take only \$R_L\$ or \$R_L\$  || \$(R_1 +R_2)\$ as DC current also flow through \$R_1\$ and \$R_2\$ .
For other parameters like \$V_{in} , R_{in} , R_{out} \$ can't even make any idea.

How can I  solve this and please,explain in detail so that in future I can solve this kind of circuits by myself.
Thanks in advance.


texts: how to find armature current in dc shunt motor in given question?

texts:
A 8.8 kW, 220 V, 1200 rpm dc shunt motor has armature resistance of 0.1 Ω and field resistance of 100 Ω.  The rotational loss is 2200 W.
Compute: a) The rated load torque on the shaft. b) The armature current.

I have worked out the rated load torque which the answer is 70Nm. However, i have no idea of how to determine the armature current. I know output power is equal to developed power minus rotational loss. Hence, I got developed power as 11000W. And developed power is equal to Ea(Ia). How to get Ea without the total current given?


texts:
For an LNA design, the simulations for the inductors and the simulation for the rest of the components (transistors, capacitors, resistors etc.) are done in two different software packages. The inductors are simulated in EMX and the other components are part of the Cadence Virtuoso package. To include the inductors as part of the design, we take the S parameter files generated from EMX simulations and set the inductor in the design to an n-port view and make it point to the S parameter files generated by the EMX program.

Now when we run a monte carlo analysis, that’s basically simulating for different manufacturing variations. This only varies the models that are part of the cadence package, not the inductors that we have in the design. The inductors are pointing to the same S-parameter files for each iteration of the monte carlo run. So the design is not being "truly" monte carlo simulated for the entire LNA design.

In EMX, there is a way to perform monte carlo on the inductors, and they would generate some n amount of S parameter files, one for each nth iteration.
What I thought could be done to make a true monte carlo analysis on the design in cadence is pause after each iteration of the simulation, and switch the file that the n-port view is pointing to and do this for each iteration. In this sense, the monte carlo run is pointing to a different S parameter for each iteration that contains manufacturing variations that were simulated for in the EMX folder.

So the question is, is there any way to pause after each iteration of the monte carlo simulation in ADE XL or using SKILL/Ocean?


texts: I recently learned about differential amplifiers and how they work; having learned that, I can’t see the need for shielding a balanced cable since the point of shielding is to catch the interferences but the differential amp eliminates all interference 100% right?


texts: Multisim - how to view Op-Amp Voltage Saturation

texts:
multisim-print

Hello! I am learning electronics in university and need to get the Voltage Saturation for this Amp-Op circuit (it might be easy but I don't know how to do it...), the print above also has the DC Sweep graph.

If you need more info I'll give it, sorry if the question is not very good, it's my first electronics question!

Thanks for the help!


texts: I couldn't figure out why are the LCD connections are not working

texts:
I defined the LCD connections but the code (written below) still gives me these errors (mentioned below.)
I could not figure out the reason (I am new in microcontrollers.)
//PS: This code is intended to show the double of the binary number applied in a specific LCD connection for a PIC16F877.
The code:

The errors:


texts: Does a given size wire have a maximum power or a maximum current that it can transmit?

texts:
I've lost my 'intuitive feel' for current, voltage and power in a conductor (like a 18 gauge copper wire)...

The wire seems to be rated by maximum current rather than maximum power... Does that mean I can get a 'free ride' by using a high voltage in order keep the wire size low when transmitting power?

Simple example: let's say Im going to run a 18 gauge wire around my house to supply power to a bunch of 12 V devices...  Can I actually support a maximum of 4x more devices if I supply 48 V in the wire system and then step it down at each destination.


texts:
I have some led strings of the type shown:

...which run off two C2032 batteries, so 6V.

I am cutting off the battery cases and connecting them to a 6V supply which is a step down converter on a 12V battery.

However, the led's are overheating and burning out.

Isn't one 6V DC supply the same as the next? How would they draw more current, just because it's from a larger battery?? Could it be something basic?

Update:

I looked up the nominal resistance of new CR2032's and introduced a resistor of equivalent size. This worked a treat. So a) I learned something, and b) it saved my project, which was part of a public performance which would have failed if my led's failed. So thanks all for sharing the knowledge.


texts: What audible difference will an audio op amp make in an audio ADC

texts:
If I were making an audio ADC based upon the PCM1804 for example , what would be the impact on the output audio from the PCM1804 if I used an audio op amp like the OPA1632?

What exactly does the op amp do to the audio signal ? I realise it will operationally amplify I.e amplify the difference in voltage between 2 points, but what will this mean for the input signal to the PCM1804?

If anyone can actually explain what happens if I connect the OPA1632 to the PCM1804 instead of not bothering with the OPA1632 it would help a lot! I would hope any answers would explain the technical differences, then conclude which option would result in the best audio signal explaining why.

Thank you!


texts: Using the STM32 Nucleo L152RE with uVision

texts:
I've been messing around with the Nucleo with mbed for the last week or so, but I'm keen to get out of that and back into some lower level C to give me more flexbility.

I have the problem, however, where I can't detect the ST-link on the nucleo to program it. I don't know if it's just because my PC only sees it as a storage device, or I'm doing something else wrong.

Has anyone else successfully programmed the nucleo outside of the mbed IDE after using it like that?


texts: PWM timer problem with HCS08 - freescale

texts:
I am using a MC9S08LH64 microcontroller's timer module to generate an internal timer for synchronization. bus clock is at 4.3 MHz, modulo is set at 4309 (TPM1MODH and TPM1MODL) and I am expecting pulse every 1.25 ms but the result is about every 3.75ms. Is there any setting I am missing here? Thank you very much

From the reference manual:

/*
 * TPM1SC: pg 358
   bit
    7   TOF need to check for this flag
    6       not used since no interrupt being used
    5   1  not used
    4   0  selecting bus clock
    3   1
    2   0  not dividing clock down
    1   0
    0   0
  */

TPM1SC = 0x08;

*Update: I have just realized that changing the TPM1MOD has no effect on the result pulse width. TPM1SC is the only register I used to set up the module. Is there any other register I need to set up for this?

Here are the source code to set up the timer:

//to set up the modulo register:
void set_base_pulse(float time_ms)
{
  int modulo_value;
  modulo_value = (int) time_ms*1000/233;
  TPM1MODH = modulo_value >>8;
  TPM1MODL = modulo_value;
}

to generate the pulses, I checked the TOF flag, every 40 times the flag goes off, I toggle the output:

for (counter = 0; counter<40; counter++) {
  while (!TPM1SC_TOF) {}
  if (counter == 39) output ~= output;
}


texts: I²C bus buffer vs extender P82B715 vs. P82B96

texts:
while searching for a way to use the I²C bus for distances about 5m I found these 2 chips P82B715 and P82B96.

I'm wondering which one I should use (I know this is up to me).

So my question is which are the pros and cons of using one chip or the other?

Do they have the same purpose?


texts: How to see sinusoidal wave from SPWM output?

texts: I am generating SPWM waveforms using complementary outputs of advance timer. I wonder how can i see the actual sinusoidal waveform on an oscilloscope which is intended from the SPWM output? My MCU is STM32F407VG.


texts:
I need to build a circuit where light is converted to sound. The light falls on a CDS cell and the current is passed through the NPN transistor to amplify it.

I know this is a very simple schematic, but what would be the real life model of this? Why is the resistor going to the ground?


texts: atmega328p measuring supply battery voltage

texts:
I have a custom PCB with ATMega328p (3V, 8Mhz external resonator) where both Vcc and AVcc are connected to a battery.

Device is in sleep mode most of the time, and only occasionally wakes to process data. Power consumption is important priority. Currently in sleep mode I measure ~ 8uA.
This circuit is working properly. I am measuring battery voltage this way:
long readVcc() {
  // Read 1.1V reference against AVcc
  // set the reference to Vcc and the measurement to the internal 1.1V reference
  ADMUX = _BV(REFS0) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1);

  delay(2); // Wait for Vref to settle
  ADCSRA |= _BV(ADSC); // Start conversion
  while (bit_is_set(ADCSRA,ADSC)); // measuring

  uint8_t low  = ADCL; // must read ADCL first - it then locks ADCH
  uint8_t high = ADCH; // unlocks both

  long result = (high<<8) | low;

  result = 1125300L / result; // Calculate Vcc (in mV); 1125300 = 1.1*1023*1000
  return result; // Vcc in millivolts
}

So far I had both Vcc and AVcc connected to a battery supply. Now I am introducing a voltage regulator (3V output) for additional component (requiring more stable 3V), and I have a dilemma - how to continue monitoring the battery level:

To connect ATmega Vcc to a voltage regulator (3V) as well and have AVcc connected to a battery directly. Would this work properly?
I can leave ATmega connected directly to a battery supply (2 x 1.5V AAA=3V), and continue using it as before. Can this cause problem with other device (working on 3V through regulator) that I am connecting to (for SPI communication) if the battery level drops low (e.g. ~2V)? ATmega is set to 1.8V BOD.

I do not use ADC except for battery voltage measurement.


texts: Problem with setting initial voltages in LT Spice

texts:
I was trying to set an initial voltage for a capacitor I was modeling in LT Spice, and I tried using the command .ic V(Vc)=20000 (Vc is the node directly after the capacitor, with ground on the other side), but the result it gave me was like this:

Circuit schematic:

There is a AC square wave source, but this is the part being measured.
I figured that it would be more of a consistent curve, but it looks like it just immediately jumps and then discharges as I think it should.  Is there another way to give a capacitor an initial voltage?


texts:
I'm building a simple magnetizer for the realization of a physics experiment, bought yesterday components for the construction of the same, I am following the scheme of this site:

The final assembly should look like this:

On the website had this indicative of these materials for the construction of the magnetizer:

Diode 1N4002 or 1N4007
Incandescent lamp 40w or 60w
Fuse 1A
The primary winding of a small transformer

The components that are bought:

Diode IN4004
Fuse 1A
Incandescent lamp 40w and 60w
transformer of 9V and 500mA

So I have some doubts regarding the material bought, I researched on the internet and saw that the diode IN4004 contains these features:

On the site that I am following, still contains the caution notice:

  The higher lamp power, the greater the intensity of the magnetic field
  created, but also the greater the current flowing in the circuit. A
  very strong current may jeopardize the integrity of the coil used. The
  values indicated in the circuit must not be exceeded.

I wonder if with purchased components, will have to change some feature of my circuit so I get the same flow of current in the coil

Edit

The circuit goes directly plugged in to 110v or 220v as shown in the circuit design


texts:
I implemented dc motor speed control project but there is one problem which i am not able to figure out .The problem is that my pid output which is float when assigned to short data type gives unexpected answer.since PWM inbuilt function in mikroc allows only short type dutycycle there is a need of float to short conversion.
please help
i am using pic16F877A.

    example
    float to short conversion:
    float pid_out;
    short duty=(short)pid_out;
    outputs:
    if my pid_out<=100
    then duty=pid_out;
    and if my pid_out>100
    duty=65535

for pid_out values less than or equal to hundred it gives same value for duty
 whereas for pid_out values greater than 100 it gives  duty value in the range of 65500.
please help unable to understand what is the mistake.
 For reading the values i used virtual terminal and uart.


texts: Is it possible to create a signal in LTSpice by using a stored data?

texts:
I have lots of sampled voltage signals data where I can plot them in MATLAB or write them to a text file for each sample.

I would like to use these samples to generate input signals in LTSpice instead of trying to mimic them.

Is it doable in LTSpice?

edit: My data samples on txt can be in the following format:

59.7435           5.0615

59.7437    5.0578

59.7440    5.0768

59.7443    5.1119

Where the first column is time stamps in seconds, and the second column is corresponding sampled voltages


texts:
I am just starting my IoT project. I want to implement a recent low-power wireless standards (6lowpan, RPL and CoAP) in my project. I found a  radio from Microchip (MRF24j40) that support IEEE 802.15.4 as a media transmitter. To coordinate the wireless system, I want to install the Contiki OS in my microcontroller. What I want to know is, whether is it possible to install Contiki OS in Atmel based MCUs (Atmega 16,etc.) and connecting it to MRF24j40 radio?

If it's not possible, is there any MCU suggestion that can I use to implement Contiki OS on it?


texts: If you put too little voltage across an LED, nothing happens, as I would expect.  However, I've seen a demo where a red LED is powered with a 1.5V cell, and it lights.  I assumee that red LEDs are 1.9v or so, and was wondering whether there is a range in which they can glow a little bit, and if so, what accounts for it.


texts:
In this circuit, the buzzer should sound when the button is pressed.
    #include <buzzer.h>

    #INT_EXT
    void  EXT_isr(void)
    {
       output_high(pin_c7);
       delay_ms(3000);
       output_low(pin_c7);
    }

    void main()
    {
       ext_int_edge(H_to_L);
       enable_interrupts(INT_EXT);
       enable_interrupts(GLOBAL);

       while(TRUE)
       {
           //TODO: User Code
       }
   }

I wrote this code but the buzzer does not sound.
How can I run the circuit without changing the circuit design?


texts: Is it a bad idea to replace pull-up resistors with hard pull-ups?

texts:
On many of my designs, there are ICs which have mode selection or similar inputs that are permanently pulled up or down using resistors.

If I replaced all these with simple hard pullups or pulldowns I would probably save 10 placements per board on average, which is not nothing. Is this a bad idea? And if so why?


texts: Will this circuit (for a guitar effects pedal) work?

texts:
I am a newbie at electronics and am trying to make a fuzz/distortion pedal. This is a schematic I have made

My understanding is that the more resistance the more gain so there is a minimum of 100 KΩ resistance, then the 1 MΩ pot controls the gain. Then there is a switch for 'Super Crunch' which is a 5 MΩ resistor. Then there are three clipping options: Symmetrical, Asymmetrical (Single-Sided) and Asymmetrical (Double-Sided). Then there is the volume pot, but I don't know what maximum resistance to use. Then at the end is the bypass switch. Would this work? Or am I being dumb. Thanks.


texts: Absolute angle or position measurement for slow movements

texts:
I would like to monitor the movement of an extremely slow object. The x,y,z-position is not really relevant to me, I am more interested in the angle.
I have come across the MPU6050 that is explained here:
https://howtomechatronics.com/tutorials/arduino/arduino-and-mpu6050-accelerometer-and-gyroscope-tutorial/
but even though it has a motion processor that corrects drift I think this is not going to work as my object cannot move for several hours up to 1-2 days.
Thus, I was thinking about a magnetometer as this one: QMC5883L-TR as a suitable IC.
I think it is not recommended to ask for specific products on stackexchange so please let me rephrase my question: what measurement technique do you think is suitable for me? I can find the appropriate modules then.
Edit to clarify my contraints:
@Kartman it is fine for me to use an absolute angle sensor. In  the installation, I am already using a  small neodymium magnet (8mm diameter, 4mm thickness) that is placed around 10cm away from the point where I need to install the angle sensor. The used sensor should not interfere with that magnet field. Can you please recommend absolute angle sensors?
@jonk accuracy of +-2-5° is ok (drift is very bad), 1measurement each 1min is fine, the only difficulty I see is the very slow movement and eventually the interference with a neodymium magnet that I am already using in the setup for a hall effect sensor.


texts:
I have a load that can be connected or disconnected from a +5V source (let's assume there is a switch). My target is to trigger an output to high-level voltage if the load is connected, and trigger it to low-level if it's disconnected. So far, the only idea that came into my mind is a current sensing circuit. I've tried with the following circuit

The problem is that, for high-side, it is not working properly (maybe cause op-amp input voltages are too close to supply?). I know there are specific ICs for high sensing, but my idea is to build it without ICs. How would yo do it?

Some additional remarks:

The current sensing must be on the high-side.
Output must be 0V if load is disconnected.
Only 5V supply voltage is available.
The load current may range between 0 and 500 mA.


texts: What's so special in "near field" and is it used in Near Field Communication?

texts:
There's this commercial technology called Near Field Communication. Turns out there're also so-called near and far field. Near field (in near and far field) is special in that electrical and magnetic fields are in some complex relation while in near field region unlike in all outer space.

What I miss are two things.

Is the "near field" phrasing in NFC abbreviation really that "near field" with special relation between fields? What's so special in "near field" that makes it especially usable for communication - I mean why not just use a weak radio transmitter to limit distance?


texts: Why is the N side thinner than the P side in a photodiode?

texts: I have been reading that a photodiode is built by sandwiching a very thin N type semiconductor togther with a thicker P type. Why is that so?


texts:
tl;dr: how to design an h-bridge to give more power to motors. pre-fab circuits are not an option.
Hi, so for my electronics class we have to build robots from scratch. So no pre-fab circuits (with the exception of Op-amps if that helps any).
Anyways, I'm running into a problem with driving the motors. I've built a basic h-bridge (see schematic), but the loss from the h-bridge is way too much. I've seen other posts about the issue, but the solution is always about buying a different h-bridge package. Not only would this be disallowed, but I'm also generally curious about the raw design aspects of h-bridges.
so I was wondering what can I do from a component level to get more power delivered to my motors? Would adding some sort of Output stage help?
H-bridge schematic, LEDs as stand in for motors:

Any help would be greatly appreciated. Thank you for reading.
edit: additional info:
@5V Vcc, the motor observed 2.80V and 0.64V (drawing ~160mA)
no significant drop across the FETs was observed.
the IRF9530 is a P-type power FET, the IRF520 is a N-type power FET


texts: Can someone clearly explain the tasks of each pin in a plug. Is there a difference between one phase and three phase plugs? Does the electricity enters our home from line connection and goes back to the generator from neutral connection? The third one is connected to ground to protect us but is it really necessary because some plugs only have two pins.


texts: I want to enable/disable 20V current with my ATmega pin. How can I connect transistor and what transistor?


texts: Can I power an ESP32 through the Vin pin?

texts:
I can't find a clear answer on this through my searches, maybe someone here can help me.
Can I power my ESP32 through the Vin pin?
What is the best way to do it?


texts: I am trying to write what is essentially the MAX697 WDT in vhdl of a CPLD rather than hardware. Any examples of how to do this?


texts:
Hello,

above screenshot depicts output configuration in one of STM32 microcontroller. I would like to examine it a bit to understand what is going on and what I can expect.

First of all the manual says we can confugure output as either push-pull or open drain. Couple of questions here:

If I understand correctly if "Output control" block produces adequate positive voltage then p-mos if off and output pin in n-mos drain - pin pulled to ground. Is it correct?
How is the above scenario (n-mos active) different then Open drain which for me can only be realized in the same way by n-mos?
Is there any other adventage of this push-pull configuration then just the possibility of having output pulled to low/high.
I've been told that in push-pull the current flow is different then it is in case of open drain but I really don't see it. In Push pull current can flow either from Vdd to PIN or from PIN to Vss. In open drain only from PIN to Vss. So it looks like no difference but that person suggested that one configuration allows internal current flow while other external. Does it really?
I see that PIN is protected by diodes. So if I put higher voltage then Vdd or lower then Vss it will be shorted imediately. Is it correct?
What is the point of Schmitt trigger for input here?


texts:
I have this situation on Proteus 8.1:

The AND components are TOO big, so I want to make it smaller.

Is it possible?


texts:
Looking through the Digilent Arty A7 evaluation board's schematic and noticed that there are two capacitors banks connected to the core supply voltage of the FPGA (VCCINT pins).  I was curious about the reasoning behind this design choice.
Why would they do this?  From my understanding it seems as though the two banks would appear as one bank to the FPGA, am I incorrect with this assumption?

The capacitors in the red box are DNI (Do Not Install) for a certain chip, there are two tiers of this evaluation board based on the FPGA needed by the user.  The DNI flag does not apply for the part shown in the screenshot.
More information about the evaluation board can be found on Digilent's website.


texts: 4-Bit ripple down counter using negative edge-triggered J-K flip flops

texts:
Ok, so as the title says im wanting to build a 4-bit ripple down counter on logisim so that I can find what 15 in binary is along with what 9 in binary is to make a mod-10 ripple down counter. But how exactly would I connect up a display or counter on logisim to record/see these results?

Edited section below.

So from what you said Jonk I came up with this circuit if you could have a quick look over it, the top four Q0 Q1 Q2 Q3 links which will be connected to the decoder then to the clock when using the Logic board, just as a heads up the board i will be using is a Logic Tutor LT345 Mk2 board so I can just make the usual connections in my lab session. Also doubt I would need to but I just connected J and K for my lab session as both J K = 1. Hopefully im close at least.


texts: Preventing the voltage between two isolated grounds from exceeding max rating

texts:
Consider the low-side current sensing application shown in Figure 1. Grounds 1 and 2 are galvanically isolated. Assume, for example, ground 1 is the NEUTRAL line on mains power (\$V_g\$), and ground 2 comes from an isolated DC power supply whose power +/- terminals are both floating relative to local EARTH ground.

The current sensor IC's data sheet gives an absolute maximum rating for the working voltage \$V_{WORKING}\$ between the IP+/- pins and "all other pins" on the IC. (n.b. To keep things simple, the IC's power ground pin (connected to ground 2) is the only "other pin" that's shown.)

I'm wondering what techniques I could/should use, if anything, to ensure the working voltage between ground 1 and floating ground 2 (\$|V_{12}|\$) never exceeds \$V_{WORKING}\$? (And note that in other applications, grounds 1 and 2 might both be floating relative to local EARTH ground.)

Figure 1.


texts: Detached antenna and connecting wire length

texts:
Since my this particular question didn't get any answer, I thought of asking a more focused question, along a path which seems a bit more feasible after few tests.

Is it possible to install the antenna of the 433MHz ASK/OOK TX module, some distance away from the module itself ? All my present tests use the antenna wire directly attached to the module, and of course, they work fine. However, if I add a length of wire to increase the distance of antenna, the whole wire, I believe, would behave like an antenna - right ? And that would detune the antenna ? Any solutions to the problem where TX module and antenna need to be spaced out ?

Edit

Based on the comment (PeterJ's) and answer (pjc50's) so far, here's what I understood as the possible solution.


texts: What causes cables to get heated up and melt in a circuit? (DC Circuit)

texts: I know lots of current can cause heat but what else? Can too much resistance in thin cables cause heat?


texts: I need the socket that looks in the picture. It is like female USB but not with metal case, only inside of female USB. I am looking for black part I will print with 3d printer white part. And is there a 5 pin version?


texts: In the book i=2 ma is given I can get this ans by solving equations but how to intutively prove that the current would be same?


texts: Ideal voltage for 12 V system, particularly with a mix of DC motors and other loads

texts:
Is there a distinct advantage to higher or lower voltage in a 12 V system?
In other words, is it better to run the system at one end or the other of the voltage tolerance: 10.8 V vs 15 V?
I specifically ask because I have both 24 V and 12 V systems on my boat. The 12 V systems consist of mostly lights, navigation equipment like GPS and VHF radio and water pumps. I achieve the 12 V system voltage by way of a DC-DC converter adjustable from 10-15 V. I have had it set to 14.5 V so far, as most of my equipment state they can tolerate a wide range in voltage. However, I was setting it high as it makes my water pumps run faster, which, in the case of my freshwater maker, yields faster fresh water output.
The drawback is that some of my cheap LEDs were failing. But they are not important and their wellbeing is not worth much in the big picture.
This makes me wonder if the slight increase in water production is a false economy if the rest of the system is less efficient at this voltage - for example, the LEDs.
I’m sure it is a wildly-complicated subject but, broadly, what voltage should I set things to? My primary goal is longevity and efficiency.


texts: How do I determine my new power requirements when switching my peripheral to Raspberry Pi

texts:
Problem:
I have just moved my camera array USB peripheral from a MacBook Pro to a Raspberry Pi 400, and the Pi can only see at most 19 of the 24 cameras that the MacBook Pro can see.  I think this is a power problem, and I am writing to check with people who are more knowledgable about such things.
Description of Hardware set up
I have a custom camera array made up of 24 USB cams, and 5 USB hubs.  I had been successfully attaching this to my MacBook Pro, and all 24 cameras have been accessible via a USB port, without the need to provide additional power to the hubs.
I am now in the processing of porting this device to a Raspberry Pi 400.
When I now hook up this camera array to the Pi, it seems to be able to only access at most 19 cameras.
I am guessing that the reduced number of accessible cameras is a symptom of there not being enough power coming from the Raspberry Pi 400 to support all 24 cameras, while the MacBook Pro probably did supply enough power.
Is that a reasonable hypothesis?
If it might be the cause, should I increase the power flowing into the Raspberry Pi?
How should I determine how much additional power I should add (current supply is 5.1V 3A)?
Each of the hubs has an optional power input using a USB-C jack.  So rather than providing the pi with more power, I could alternatively add extra power to the master USB Hub (USB Hub 5 in the attached diagram), and leave the power to the Pi unchanged.
Is there any advantage to powering the master hub directly?
Alternatively I can add power to each hub separately. I would have to the the DC power coming off a house current wall wart, and then divide it in parallel to each hub.
Is there any advantage to this approach of powering each hub independently?
I would only want to have one power cord coming in, so I would have to build a 5 way power cord splitter, so that's a disadvantage I see.
Data:
With an in-line USB volt/amp meter,  I am seeing that the normal Voltage and Amperage going through the meter when the Pi is idle is about
5.08-5.10V 0.27-0.30A Pi Idle
4.73V      1.30A Min Voltage and Peak amperage on Pi during camera polling
4.71-4.78V 1.33A MacBook Pro IDLE
4.71-4.78V 1.33A MacBook Pro during camera polling.
USB connections diagram.

UPDATE:
I have created the following graphs that show how voltage and amperage change from idle state to when the cameras are being polled. The two lines with the large changes represent the Raspberry Pi tests, with the Normal 5.1V 3A power supply, and with a larger 96W power supply (same as used by MacBook Pro.   The relatively stable line is from the MacBook Pro which shows no variation during camera polling.
I am guessing that the Raspberry Pi is limiting output to 5A - and that is apparently enough to power 18 of the 24 cameras.   In contrast the MacBook Pro seems to happily supply more power (up to about 6.6A).  That's the same ratio of 24/18, so that is probably why the Mac can power all the cameras, but the Pi cannot, even with additional power.
I am trying to find a way to supply the additional power directly to the hubs in hopes of working around this problem, but initial testing with additional power directly to the master hub, didn't resolve the problem.


texts:
One of the LEDs in a plug equipped with over-voltage protection does not light up when the device is plugged into the 230 V mains. It has worked well for a while since the product was purchased. An inductive load was used with the plug.
After I took it out of its board, I checked it with a multimeter on the "diode testing" mode and found out that it conducts in reverse, with a voltage drop of 1 V. Despite the fact that it does not turn on, my multimeter shows there is a forward voltage drop of around 1.8 V, which seems to be a normal value for a healthy LED.
I was expecting open-circuit and short-circuit failures, but none of these seems to be my case. Since it conducts in reverse, it must have experienced reverse breakdown at some point, too.
Here's a schematic which can give you and idea about the circuit in which my component was:

simulate this circuit – Schematic created using CircuitLab
The LED and its resistor are in parallel with two varistors, 230 V supply and the load which connects to the plug.
Here's a photo of the LED:

What could have caused something like this?
Has anyone seen something like the aforementioned LED has failed? Maybe something very similar?
EDIT: The green LED did turn on with the help of a few batteries, but all the other things still apply; still showing reverse voltage drop of 1 V without turning on (both for multimeter and batteries methods). Still doesn't turn on when connected to the multimeter.
NOTE: The green LED was replaced by a new one in the device it was part of and that new LED lights up without problems.


texts: How to select a DSP chip for ECG/EMG signals

texts:
I want to select a DSP chip which I can use for some ECG/EMG signal processing. I am looking for an evaluation kit. The input signals are already in digital format (taken from phsionet.org). I am also looking for the following constraints:

Linux OS (I intend to do multi-threading / multiprocessing)
A gcc/g++ compiler for that DSP architecture
External connectivity using Ethernet
SD card storage so that I can store data in it

I think a DSP with ARM architecture might suit my needs best. Any help or guidance would be greatly appreciated.

Thanks.


texts:
I'm building a circuit to switch between a USB 5V source and a battery source that ranges from 2V - 3.3V. The rest of the circuit runs on 2V - 3.3V so the USB 5V source is passed through an LDO before supplying power to the rest of the circuit. So,

If the USB source is connected, it should draw power from the USB source and not from the battery
If the USB source is disconnected, it should draw power from the battery

I understand that there are similar questions here (USB/Battery switch) but I am wondering why this simplified design doesn't work:

When the battery Vcc drops to 2V and both USB and battery are connected, a lot of current (500mA) flows into the drain of the FET (the source of the FET is connected to battery Vcc). Why does this happen? Shouldn't the FET be off when Vg (3.3V) > Vs (2V)?

Also, I understand that my circuit is rather strange; Vd > Vs and Vg > Vs and I don't really see what happens in these scenarios in the transistor data sheet (ZVP3306A). I guess this design is not covered by the transistor data sheet? And feel free to suggest more designs.


texts: Estimating SOC using coulomb counting with DSP

texts:
I am trying to estimate the SOC of a battery using the Coulomb Counting technique. I am implementing the following equation on a DSP inside PSIM:
$$
SOC[K] = SOC[K-1] - \frac{I_{Bat}}{Q_{Bat}}\cdot{Ts}
$$
//Performed at T=0 of the simulation
double SOC[2] = {0.0, 0.7};
double Ts = 1/12000.0;

//Performed on each simulation step
I_Bat = in[2];
SOC[0] = SOC[1] - (I_Bat/(2.5/2000.0))*Ts/(3600.0);
out[1] = SOC[0];
SOC[1] = SOC[0];

The initial state of charge of the battery is 0.7. The results I am getting, however, are not very precise:

Actual SOC in red. Estimated SOC in blue.
Am I missing something in my implementation or is there a way to increase its accuracy? Thanks for your time.
Update: I am gathering the I and Q as follows:

For I I am sensing the battery's current with a gain of 1. And as for Q I am using the battery's nominal capacity.


texts:
I have another question about PCB layout. I'm designing using this guide:
https://www.ti.com/lit/ug/sllu149e/sllu149e.pdf?ts=1618900105338&ref_url=https%253A%252F%252Fwww.google.com%252F
I don't find nothing about problems between power planes and USB traces. Will it be problems if I create a power plane under the component and USB traces? Thank you so much!


texts: SPI slave randomly missing bits in response

texts:
I've connected an MCP3008 to a raspberry pi. First on a solderless breadboard, where everything worked correctly. Then on a prototyping board, where the only difference is that the chip is externally powered. The problem is now that the response from the slave is occasionally missing bits (the slave fails to pull the signal up for every bit that it should). Here is a series of readings taken at a 0.01 s interval:
[3.4, 3.39, 3.29, 0.0, 3.4, 3.4, 3.4, 2.55, 0.0, 2.98, 3.39, 0.0, 3.39, 3.3, 3.19, 3.4, 2.98, 3.4, 3.4, 0.58]
The readings are normalized for Vref = Vin = 3.4.
I've tried:

Redoing the soldering,
replacing the MCP3008,
adjusting the SPI frequency (currently at 1.35 MHz),
checking the connections and voltages using a multimeter
using the piscope to examine the serial communication (tricky, because if I set the frequency low enough to get a good reading, the chip rarely returns any values at all)
grounding unused inputs

The PCB has copper wire from the header to the chip for the SPI interface, about 5cm long. As far as I can see, that should be fine for SPI. SpiDev is set to use mode 0.
Any other ideas as to what might be going wrong would be hugely appreciated.
Update:
Connecting the Raspberry Pi ground to the external ground solved the issue, so it looks like the lack of common reference voltage caused the mcu to sometimes not pull high above the necessary threshold.


texts: Why do many ultrasonic sensors have specific frequencies (48 kHz & 58 kHz)?

texts:
I am working in the automotive industry and I found that many of the ultrasonic sensors on the market (sonars) have specific frequencies, namely 48 kHz and 58 kHz. (Not that other frequencies are nonexistent, of course) Why is this so? I can’t seem to come up with a reasonable explanation. Thank you.
Edit:
I did a Google Search
Ultrasonic Sensor Frequeny "xxxkHz"
where xxx is some integer, and they returned the following count of results:
Freq  # of hits
46kHz 2040
47kHz 3120
48kHz 10600
49kHz 849
50kHz 277000
56kHz 1950
57kHz 696
58kHz 15900
59kHz 703
60kHz 84100
There are peaks in 50 kHz & 60 kHz, because they are multiples of 10 kHz. The peak in 48 kHz & 58 kHz is not as pronounced as I had expected, so this may be just by accident.


texts: DC-DC converter not simulating correctly

texts:
I am trying to design a solar charge controller to charge a 12V battery, my solar panel is made of 9 cells that are 5W and 0.5V per-cell. I would like to make a booster circuit to get the voltage up to 13-14 in order to charge the circuit.

I am planning on using a MC34063A for this and I found multiple examples of what I am trying to do.

The first arrangement I have tried was Here, but when I get the components into LTSpice and try and simulate it, I get very different results than what I am expecting.
The second is here, but again when I get the components into LTSpice I am getting very different results than what I am expecting to see.

I got the spice model for the MC34063A from this post

Here is a picture of my current spice model, which is representative of the second configuration.

Here is the picture of the results of the simulation.

I am hoping to see 12V at C3 and currently, I am getting the source voltage. Just over 5V.

If someone is able to show me the errors of my ways I would be greatly appreciative for the help


texts: Faraday's law of induction clarifications - Area change over time

texts:
I am reviewing the Maxwell equations hoping to master them quite better than I did when I was on the school bench.

The Faraday's Law of induction leaves me with a question that I can't quite understand.

First Lenz's laws state that the EMF's relationship with the magnetix flux is :
$$EMF= -\frac{d\Phi_B}{{dt}}$$

Then, the magentix flux \$\Phi_B\$ would be given by the area integral of the flux density.

$$\Phi_B = \iint_S B\cdot dS $$

Well, now Wikipedia states that the Faraday's law of induction goes as follow.

$$\oint_\Sigma {E \cdot d\ell } = - \int_\Sigma {\frac{\partial B}{{\partial t}}\cdot dA}$$

What confuses me is that the flux derivative is inside the surface integral. A simple substitution of the flux variable in the two first equations would make the flux derivative outside of the area integral.

I know that I can bring the time derivative out of the surface integral if dA is constant, this is purely mathematical. Although, the way I understand the Faraday's equation as it is presented above, a change of the area over time will not affect the EMF.

On the other hand, one of the online demonstrations of professor Walter Lewins explains the case of a sliding copper rod in circuit inducing EMF in a closed loop as the area grows for a constant magnetic field.

If we do this exercise with a constant field B=10and a area that changes, I understand we would get:
$$EMF= \oint_\Sigma {E \cdot d\ell } = - \int_\Sigma {\frac{\partial 10}{{\partial t}}\cdot dA(t)} = - \int_\Sigma {0 \cdot dA(t)} = 0$$
Am I wrong ?

What am I missing here ?

Thank you


texts: Building a buck converter using CMOS 555 with mosfet driver

texts:
Can I use ICM7555 IC to generate 300 KHz PWM signal and feed that PWM to IRL2104 mosfet driver to build a non-isolated DC to DC buck converter?
I'm asking this question because I couldn't find any decent buck converter design using CMOS 555 timer that have voltage feedback and a mosfet driver, thought to myself maybe it is not possible or at least the idea may have fundamental problems.
I've very little knowledge about switching power supplies, go easy on me.


texts: Are all the DIP-16 packages the same for PCB library design?

texts:
I am designing PCB library for a component whose Package is DIP-16. I have already footprint of this Package in other components. Can I use them interchangeably in the new component in terms of their size? Are their size the same?
Thanks for your contribution.


texts: Colpitts Oscillator - Cap identification

texts:
A chip I'm working with (SA612 mixer) has an internal BJT, and it requires the user to add discrete components to make an oscillator of a certain frequency to drive it. It gives generic Hartley and Colpitts layouts as examples:

Relavent part of SA612 internals:

The Hartley layout seems pretty easy to understand: C1 and L1 form the tank, and C2 and C3 are coupling caps. But the Colpitts layout doesn't look very much like the traditional Colpitts oscillators I'm used to, and I'm struggling to understand the role of each component.

Best guess: Perhaps C4 is a coupling cap, and the other three caps make up the capacitive half of the tank in the arrangement (C3 + C1)||C2 ? But then why do we have the parallel C2? Is it just for fine-tuning like some kind of dual of the Pierce configuration?

Thanks!


texts: FDCE flip flop primitive on altera quartus?

texts:
I would like to know the altera quartus primitive equivalent to the FDCE flip flop on Xilinx ISE. I think that DFFE primitive might work however I am not sure about the CE and CLR pins equivalency. Also the PRN pin confuse me.  I have included a link to the altera documentation that I have been using so far.

http://quartushelp.altera.com/14.1/mergedProjects/hdl/prim/prim_pu_pinstub_names.htm


texts: GSM interference on an wireless micrphone

texts:
I am getting GSM Buzz on a wireless micrphone system.  The interference is coming from the Micrphone itself as it is transmitting it in the audio and is not being caused by direct RF interference with the transmitter or receiver.

This is an RV2 wireless sytsem from EV (uses TELEX equipment). The unit in question is HTU2 microphone (HT-500 bosh/Telex).

When a GSM phone is held close (with in 1') and the phone receives a SMS you hear the pit pit pit sound of the SMS/GSM packets being sent/received.

I am was thinking I could shield the microphone and internal components and just make sure I didn't shield the antenna area (couldn't find the actual antenna -fcc:B5DH219 docs say its TP11 but didn't see any antenna in that area).

At this point I see there is an RF choke at the mic input, but I am left wondering if Ferrite beads added to the mic input wiring would work to solve the problem.  All the other answers speak about using ferrite beads on the wires going to the receive but none talk about put microscopic ones inside the wireless microphone itself.

Anyone have experience in eliminating hte GSM noise from the Ev RE2 Clear Scan units?  The noise persist on any frequency the units are set to.

I have seen other post such as Why is GSM interference audible?
Why does GSM cause speakers to buzz?
Killing GSM Buzz with Ferrite Beads


texts: chip select on one to one spi connection

texts:
I connect an imx233 (master) and atmega168a (slave) through SPI. I am trying to debug the communication. I have problem with imx233's chip select, therefore I connect CS of the AVR onto the ground. Could anyone tell me if I really need to use chip select as I have only one slave? I asked that question on different forums and some says I have to have the CS, some says it is not necessary if I have only one slave and connect the CS onto the ground.

I would be grateful if someone can clear my mind if I really need to have the CS on one to one SPI connection or not? and why?


texts:
I am designing a buck converter with PWM circuitry for a school project to drive a MOSFET switch to keep my output voltage constant.
The specs are:

input voltage of 20v DC +/- 4
output voltage of 5v DC
Maximum output current of 1A
No more than 10% change in voltage over entire range of input voltage and load
Min. 80% efficiency at full load
No micro-controllers can be used

I am having trouble keeping the voltage constant with the PWM circuitry. When simulating the circuit, the voltage goes to around 5.7 to 6v. Can you please help me correct the PWM circuitry and/or the inductor and capacitor values? They may not be correct.

EDIT: The lm555 Timer with the BC557BG transistor creates a ramp voltage by repeatedly charging and discharging capacitor C6. The 741 Op-Amp is set up as a differential amplifier with a gain of 1, which will subtract a sample voltage from the output with a reference voltage of 5v. The output of the 741 Op-Amp goes into an input of the lm311n voltage comparator, and the ramp voltage into the other input, the output should be a square wave with varying duty cycle to drive the MOSFET. Click for full-size.
EDIT:

The light blue lines represent 5v from the zener diode, black for ground.

The 555 Timer Sawtooth wave generates at 30kHz

The main Buck converter

The calculations I used to select inductor and capacitor values.

I solved these values by setting LIR to 0.2 and dV to 75mV.

Feedback circuit

Summing amp and voltage comparator

The Voltage to the gate pin of the MOSFET

The comparator inputs

The output voltage before and after the inductor

The output voltage does not stay around 5v, it slowly increases to 10v


texts:
I am trying to understand the way a JFET op-amp works. I have a circuit like this:

You can see the LF347N chip I am using.

The IN+ terminal is connected to a TTL switch providing 0V or 5V. The VCC+ and VCC- is connecting to +15V and -15V. I just searched the manual of the LF347N, I don't understand what signal is at the OUTPUT terminal. Is it voltage or current? What's does the above circuit really do? My guess is that the TTL signal switches the output between 15V or -15V.


texts: Increasing efficiency of a kinetic energy battery charger

texts:
I want to use Faradays law to convert the kinetic energy from actions such as a jog/shake to produce electricity to ultimately charge a battery.

Materials

Neodynium Magnet 3/4 diameter (2)
Solenoid casing (x2)
Enameled Copper wire (x2)
1800mAh battery
Spring (x2)

Plan

2 solenoids with the magnet inside connected to a spring that will move up and down or use urethane stoppers. Then use a rectifier to convert AC to DC and charge the battery.

So I'm essentially adopting the faraday flashlight concept using two solenoids. How do I calculate current output and how do I to go about increasing efficiency?


texts: Supercapacitor spot welder - which capacitors to use?

texts:
I built a spot welder using a big transformer (approximately 4kW from an old welding machine) but I now need to build a spot welder with more power (more current.)

The current spot welder works great for steel/nickel coated steel but lacks power for spot welding copper.

The 4kw transformer welder has approximately 8V open circuit voltage. I am using 35mm2 copper wire, approximately 1 meter total wire length (back and forth) from the transformer to the spot welding electrodes.

I think using super capacitors is my best option for building a higher power spot welder.

According to my research I need approx 3000 amperes-4000 amperes of current to weld 0.2mm copper (which is my goal.) The capacitor discharge time should be <20ms if possible (the lower the better I think.) PS: this amperage amount is based off of the following website: https://sunstonewelders.com/product/linear-dc/ and a comment under the following video where Sunstone comments that for welding two plates of 0.25mm copper together with this machine you need approx 4000 amperes (video: https://www.youtube.com/watch?v=16JOF-bYgWE)

Would something like this (or a combination of a few/many of these in series/parallel) be suitable for this purpose?

https://www.aliexpress.com/item/32950120538.html?spm=a2g0o.productlist.0.0.1fc72679PGnQqn&algo_pvid=e5b35dfe-59f6-40ee-92cd-bb0dd81b5685&algo_expid=e5b35dfe-59f6-40ee-92cd-bb0dd81b5685-11&btsid=7ac9af34-07ad-405d-a2b8-8a1f6cfae7c3&ws_ab_test=searchweb0_0,searchweb201602_8,searchweb201603_52

What open circuit voltage should I be aiming for approximately to achieve the desired amperage? What would be a suitable capacitance value for the capacitor bank?

The spot welder pen I'll be using: https://www.aliexpress.com/item/4000159606521.html?spm=a2g0o.productlist.0.0.46332b7duxXLLm&algo_pvid=86b2cbd1-50eb-4bf4-b0f7-9a33915fa1dc&algo_expid=86b2cbd1-50eb-4bf4-b0f7-9a33915fa1dc-2&btsid=0e8acf7d-32fb-440e-badc-79556c2d2698&ws_ab_test=searchweb0_0,searchweb201602_8,searchweb201603_52

Any input is greatly appreciated.


texts: USB type-C Configuration Channel (CC) Circuit

texts:
We want a phone to be able to function as both a source and a sink of power. When using USB type-C, pulling the Configuration Channel (CC) to ground with a resistor causes the phone to become a source of power. The phone acts as a sink of power when “CC” is not pulled to ground.
We are designing a phone case that needs to sink power from a phone. We want the phone to become a source of power to the case when they are connected. The phone must be a source of power when in the case, unless a USB type-C charging cable is plugged into the phone/case, where the phone should switch to being a sink of power and the charging cable begins to source power to both the phone and the case.
We planned on accomplishing this by using a 2n3906 PNP transistor. We have a 5k ohm resistor connecting the emitter to the “CC” pin, and the collector connected to ground. A 5k ohm resistor connects the base to the 5V from the charging cable. When the charging cable isn’t connected, the connection to base reads 0V. The Emitter and Collector should short, pulling the “CC” pin to ground, when there is no current applied to the base. But this doesn’t happen. This could be because the base is floating when it is not connected to the 5V from the charging cable. It could also be because there is no current coming out of the “CC” pin so it can’t go through in the first place. Why does this not work? Is there a better solution?


texts:
I've been working with my Arduino starter kit for a while and learning the basics of electronics. Now, I have a project that I would like to move off from the standard bread board that came with the starter kit. I'd like to make the entire board configuration smaller so I can fit it in tighter places. So my question is, how do you go from prototyping on a standard breadboard to a final product? By final product I mean a more compact board.  Right now this is what my mood lamp looks like for example:

I'd like to be able to move from the breadboard there to something smaller that I can stack that is more permanent.

I realize this may not be one-hundred percent clear as I'm still really new to electronics in general and I'm having a hard time explaining myself. So please let me know if I can help clear up anything as I'd love to get this answered, thanks!


texts: I have a circuit with a voltage regulator, IC 1 and IC 2, all of which are placed next to each other. The output from  the voltage regulator (~2.5V) supplies power to IC 1 and IC 2. IC 1 is an oscillator ~ 80MHz and drives IC 2 with current around 5 mA. IC 2 is a frequency divider and reduces the frequency down to ~1 MHz. IC 2 drives a capacitive load of a few pF. Two parallel bypass capacitors 0.1uF and 1nF are used here. My question is that is it okay to share bypass capacitors among the output of voltage regulator, IC 1 and IC 2?


texts: Sizing welding conductors with 6000A max current

texts:
I’m trying to size some welding conductors  per the following information.
The welder will be used once a day for 2 seconds only. 6000A of current will be drawn through the conductors during this time. The power supply provides 10v. The conductors shall be 8 feet in length.

It seems like the largest welding cables are 500mcm. I would like to do a calculation that shows the temperature rise in the cable would not exceed the maximum rating of the cable, even though the cable is not rated for 6000A. Can anyone help me with this?

The cable I’m looking at is general cable carolprene 500mcm (500kcmil) stranded copper welding cable.


texts: Does anyone know what the state of the PORT pins are on a PIC when flashing the part?  I am running a PIC 16F916 with an ICD3 programmer, and the IO pins are performing various functions, and need to understand what state they are in during programming when the PIC is energized.


texts: Getting frequency of a signal from its phase

texts:
How Can I get the real time frequency of a signal from its encoder phase angle. The encoder gives us a triangular wave from (0-2*pi). If I use derivation, I get discontinuity which provoke spikes.

Thank you.


texts:
Question:

I was asked to use mesh analysis to find the Vx and Ix.
 I tried that out but got stuck see my working here.

please, can someone help show me where I'm getting wrong?


texts: IEC 61000-4-5 2 kV chassis ground to neutral and live surge DC

texts:
I need guidance for passing the IEC 61000-4-5, 2 kV Surge test from the AC ground (protective earth, PE) to the neutral and live wires. This grounding techniques may be a bit different that passing FCC or CE emission tests and a bit more complicated.
How does DC board grounding be done in a multiple boards design interconnected (e.g. USB) installed in a metal enclosure feeding off an AC power supply? This is a bit more complex than a single board connection to Chassis ground.
Should the AC ground and DC power supply grounds be tied to the metal enclosure at one point by the power supply module and all the other board DC grounds be isolated from the metal enclosure or the boards DC grounds should also be solidly i.e. low inductance be connected to the metal enclosure?
What about the board interconnect cable shields (e.g. USB)? Should these be connected to each board DC ground or connected to the chassis ground and totaly isolated from each board DC grounds?
It is assumed that digital ground and DC ground are the same on all boards and there are no analog circuitry involved.


texts: Why is a capacitor placed in parallel with oscillator output?

texts:
I have a circuit board with an oscillator and I'm curious about why there is a capacitor hooked up to the output.  The oscillator is a SWO series HCMOS Square Wave output crystal oscillator.  The schematic of the oscillator connections is as follows.

               +3.3V
                |
   ---------    |  C=0.01uF
NC-| 1   4 |---------||-----GND
   |       |
GND| 2   3 |---------->Direct to FPGA input pin
   ---------    |
                |
                = C=15pF
                |
               GND

The data sheet (select H22/H32/H53/SWO) does not reveal much, but there is a "Load" section that says the max load is 15pF.  Specifically, it says:

  Load |   15 pF  ;  ( 30 pF and 50 pF load are also available for +3.3V and +5.0V VDD)

In such a circuit, is the load the capacitor or the FPGA input pin?  If the load is the capacitor, why is the load needed for the oscillator?  What is its purpose?


texts: Problem programming PIC18F97J60 with PicKit2

texts:
I'm having a problem programming a PIC18F97J60 with pk2cmd.exe. Using the same hex file I can program the device fine with MPLAB and the PicKit2 programming utility, but I'd like to be able to program the chip from the command line. The chip will program, but verify fails. I should mention that I have the code protect bits set on the PIC18F97J60.

Original Configuration:
 - PK2CMD.EXE v1.20
 - Device File v1.55.00
 - PICkit2 Firmware v2.32.00


texts: is there atmega 128 basic circuit for every project?

texts:
This is my first Atmega project so I have following questions:

Do I have to connect all those gnds and vcc's?
In programming I used Vcc Reset Gnd Tx Rx SClk of USART0 is that okay?
I didn't used external clock generator (quarks) because       I'm planning to use inside clock?
Is there any fundamental circuits or pins that must be connected to work simple code? (I connected only Vccs and Gnds)
Is there simple circuit that tests if the     atmega 128 is   working or not without programming it?


texts: I have a source of power which can provide up to 300 mA at 1.5 V DC, however I would like to power a circuit which uses 900 mA at .5 V DC. What would be the easiest way to do this? If it was AC I could just use a transformer.


texts: How do BIOS controls/settings affect hardware?

texts: What exactly happens when you change the configuration settings in BIOS? Does it change some register value in the subsystem's register set directly?


texts:
I designed this PCB in KiCad

But when I print it (PDF), it looks like this

Some cupper has desappeared and some tracks are wrong. As you can see, it is quite different from the original design.

How can I fix this?


texts:
As a part of my school project I have a timer astable with NE555 and I need to generate a square signal. It has 12V supply and 65% duty cycle normally.

In my simulation on LTSpice I get exactly what I want but when I do the setup on my breadboard, although I have the same duty cycle I don't have 12V-0 as the peaks for my output, it is 10.4V.

It's not a very important problem but since it's a school project I have to explain the cause of a such difference in my report.

I can't read the manufacturer's name on the component and I have tried with different NE555 we have in the lab but there is always an offset of about 1,5V. Probably it's because something inside is not ideal but I just need to know what.

I put the setup just in case.

Thank you!


texts: Units for fourier transform of measured voltage

texts:
I have a measured voltage signal that I want to present in the frequency domain. My current process is to take the FFT of the signal, then use \$20 \text{log}_{10}|X|\$ where \$|X|\$ is the magnitude of the complex frequency domain representation of the voltage signal. This gives me decibels proportional to the power of the signal.

What are the units of this representation?

They can't be pure decibels as they are not relative to the input signal. I'd like to present the data as dBV or something similar but this seems to require RMS measurements.


texts: How to learn circuit design if I already know some circuit theory

texts:
I'm a recently graduated electrical engineer, but my curriculum never focused on electronics, besides the standard introductory level courses. I specialized in telecommunications and I mostly work on the software side of things, with some FPGA design thrown into the mix.

I'd like to learn to design circuits compliant with the "good practices" found in industrial designs. For example, a simple circuit could work without adding bypass capacitors to stabilize voltages, but this surely would be frowned upon by an experienced designer. Another example would be properly protecting a circuit.

I believe this is the kind of stuff that you can "pick up on the job" when your work is reviewed by an experienced designer. Eventually this becomes second nature and you end up learning all of these good practices. Is there any hope for a hobbyist like me to learn this stuff?


texts:
If I have only +-5v source, can I boost it up to +-80V ?  If possible, can you recommend a part?

If not possible, how should I combine multiple booster to make it to high voltages.  Thanks


texts: Generate a false encoder signal CW/CCW 1/4 shifted

texts:
I need to generate a 10-100khz square signal freq. to simulate an encoder.

I'd like to be able to simulate CW and CCW, shifted by 1/4 th signal. I've thinked about a crystal with a pot and some logic gates. But don't have enought experience to create a circuit like this.

Can you redirect me to a sample schematic or components to start with?

Ex.

/* UPDATE */

10khz-100khz
24v

Why: it's becouse I'd like to have a tool to simulate motor encoder output to debug my system which has an encoder input.

A micro or develop kit it's too expensive and overkill. Also low cost micro have difficults at this freq.


texts:
I am currently trying to understand a bit something about impedance matching. As I understand it, if you have a source and a load, if you wish to transmit the maximum power from the source to the load you have to match the impedances. Here is a picture that I took from this datasheet (at page 26). It is a sensor with a RF interface. We have some pins for the RF transmission.

We consider the 434MHz frequency. The impedance of the output of the IC is \$360+j300\$. As I understand it, they want to match this to the 50R antenna impedance using L2 and the \$330pF\$ capacitor. But it is strange because since we have:

\$X_C=\frac{1}{2\pi Cf}=1.1113\$

\$X_L=2\pi Lf=73.62\$

So after the inductor and the capacitor, the impedance is going to be
\$360+300j+73.62j-1.1113j=360+372.5j\$
which is different than 50R. Why is that? What is going on here?

edit :

The impedance after the matching should be 360+300j no? So why in the image below the point 4 is between the lines for 100j and 250j?

@Aenid, I don't get the last curve (from 3 to 4). You say it is due to a 3pF parasitic capacitance (it is on a admittance line) but I get \$ 2\pi f C=2 \pi \times 434 \times 10^6 \times 3 \times 10^{-12} = 0.0082\$

And why is connected to VRF and not across the RF and RFVSS lines?


texts: How to show component value on Altium Silkscreen?

texts: The Silkscreen of my Altium PCB project only shows Reference Designators of components. I want to  show component value or part number instead of the reference designator on the silkscreen. Is there a way to do that for all components on the PCB top layer instead of doing it individually for each component one by one?


texts: What is this component and what is its use?

texts:
I found this in CRT TV on the CRT tube driver PCB.

What are they and what is their schematic symbol?


texts:
On Aliexpress I am finding many cheap development boards with ATtiny167 and a USB connector.

From what I can gather these boards permit USB programming through USB emulation. Can anybody point me to more information on how this works?

I imagine, there needs to be a bootloader that does the USB emulation part? Is the code for it available anywhere?

I have been searching but could not find any useful information. I think I must be using the wrong keywords...

EDIT 1: justme asked for links to an example of the boards I am referring to.

One example would be this Aliexpress offer:


texts:
I am on a 4 layer PCB and one of the layer is a power allocated plane. I don't have only  one rail but 4 or 5.
So far I have made some traces between the differents points where the components and vias are connected to each other on this rail. I suppose this configuration (keeping only traces) can probably work.

Now, I found out that most of pcb design are using polygons instead of only trace to create power layer rails. I know how to make polygon, but what I have difficulties with, is about drawing them properly to make them to be adjacent properly to each other (I suppose the game is to fill the full plane by having polygon to span all the plane leaving no "hole" on the plane, right ?). By this I mean : I have difficulties to establish shape, width and height. I understand that a possibilty is to coat the trace and to expand. But how to expând properly ?

How is it recommended to process  ?

PS: I am using Altium


texts:
I was doing one of the problem sets when I stumbled upon this gem.

I know that for oscillation to occur, the gain has to be greater than 1.

The loop gain I computed is

Could anyone suggest any approach towards the problem? Thanks.


texts: How to synchronize two microcontrollers to micro-second accuracy?

texts:
I need to synchronize two micro-controllers so that they can measure the speed of propagating waves. The time delay measurements need have microsecond accuracy (error less that 1/2 of a microsecond).

I have two micro-controllers (ATmega328) which use a 12MHz crystal.

They are both equipped with Bluetooth transceivers. The Bluetooth transceivers send and receive packets with a jitter of ~15 millisecond.

I hope to synchronize the micro-controllers using the Bluetooth transceivers, or some other creative method.

I have tried synchronizing them by touching them together, but I need them to stay synchronized for about 10 minutes, and their clocks drifted too fast. Maybe if it was possible to accurately predict the clock drift, this method would work.

How should I go about achieving this synchronization?


texts: Need help finding a solution to recharging old Li-ion batteries, maybe a power supply

texts:
Sorry in advance if I say anything stupid, I am in no way an expert in the field. Everything I know is pretty much self taught through years of experience in refurbishing mobile phone.
 I deal with hundreds of phones that are sometimes decades old. Most of the batteries are still working, but I need some sort of solution in recharging them. I have reached the internet far and wide for a device to suit my need but at this point I'm not sure one exists so I need your superior expertise.

So here is the situation. A lot of these batteries have been discharged for so long that they will no longer accept charge from the phone, appearing dead. But giving it a couple of seconds boost with a slightly higher than recommended voltage will bring it back to life and most of the times the battery will be working fine and hold good charge after. The problem is, I rely on primitive technology. I have an adjustable DC power supply that can be set between 3v-12v. When I try to resuscitate a battery, I set it to 9v and touch the appropriate pins to the battery a few times for a split second, and when the power supply's LED flickers a little it means the battery draws power, therefore is alive and can now be recharged.
 Another method, even more primitive, is this phone charger with a LED indicator on it. When idle is green, when the battery takes charge it goes red, when there is a fault in the battery it goes Orange, when the pins are shorted the LED goes off alltogether.
 What I need is some sort of power supply with an active display, maybe able to set voltage and amperage output, (there are many out there) but I also need to see the power it that it is drawn by the battery, maybe the recharge level, some sort of live feed from the battery as it is being recharged.
I the closest thing I found are those Li-po chargers for RC models but not sure if those are safe for li-ion.
I have a few of those cheap Chinese universal battery chargers but are very unreliable and I found only work on good batteries with some charge left in them.
 My budget is not very high, I found some industrial grade stuff for hundreds of ££ but for my small business, it would not be a smart investment.
Any help or suggestion would be appreciated!


texts: Find Voltage induction flux through the circuit

texts:
Find the max voltage induction on this figure.

Ok. My doubt is:

Consider that a << d like the question said:

So what have I missed on my analysis? If I want to solve this questions and consider in any moment that a << d the answer wouldn't be the same?


texts: 100A Constant Current Supply for Low Resistance Load

texts:
I have a 11.1V LiPo battery that can supply 100A. It's being used for a coil gun like in this image from electroboom. (The difference being he uses a power supply with built-in current limiting, connected to the wall, whereas I'm using a battery).

simulate this circuit – Schematic created using CircuitLab

There is extremely low resistance, as its mostly just going through a wire. It would seem that the magnet must induce a reverse voltage, or somehow use power, but I have no clue how much. So, it surely can't just use a very low voltage at all times. All the guides I have found are for only around 1A constant current sources. How would I make one for 100A?