texts: Spectrum analyzer as source of electromagnetic interference

texts:
I was wondering if someone could enlighten me on this. I would like to know whether spectrum analyzers can be inherently the source of interference to other components or not?

Following is the block diagram of spectrum analyzer which is copied from (Frenzel, L. (1995). Communication electronics. New York, N.Y.: Glencoe.)


texts: Why not use audio codec chip as measurement ADC/DAC?

texts:
I am working on a project that needs simultaneous ADC/DAC.  The specs of the on-board ADC in typical microcontrollers are pretty weak, and separate ADC with good specs are much more expensive than audio codecs.  For example, compare these three options:

(A) STM32F373 has three 16-bit, 50ksps max ADCs which reach just under 15 bits effective.  This is maybe the best from ST for high resolution ADC; it also has some high-speed 12-bit ADCs and some DACs.  Price: $3.26.

(B) an I2S-based audio codec, the PCM3168A has six 24-bit, 96ksps ADCs with 17.5 effective bits (if my reading of the datasheet is correct).  This also has eight DACs with similar specs.  All inputs/outputs are fully differential, and the highpass filter on the ADC can be turned off.  Price: $4.90.

(C) the least expensive TI ADC with similar specs is the ADS1271, a 24-bit, 105ksps ADC with also ~17.5 effective bits.  However, this is a $6.31 part, and has only one channel!  A four-channel part goes for $14.65.

Thus, using audio codecs for measurement seems rather attractive.

Why not do this?  Are there any unexpected drawbacks to using audio codecs for measurement?


texts:
Suppose I have a 75w solar panel. At full sun shine it is giving 17 volts 4.41 Amperes 17 × 4.41 = 75 watt. My MPPT controller converts it to 12 volts and 6.25 Amperes 12 × 6.25 = 75 watt. I know that MPPT is droping 17v to 12 by setting the switching PWM duty cycle.

The thing I can't understand is how the MPPT is compensating the voltage in current? How it is making 6.25 Amperes when there is only 4.41 Amperes available? It will be very helpful if any one can explain it using using the buck converter circuit.

I searched whole Internet but I could not find any answer to this question. Or maybe there are good answers but I am unable to understand them.


texts:
I am in need of a stable 5v source, max current around 200mA for a pocket oscilloscope. I have tried a powerbank, but the step-up converter puts through too much ripple that messes with the Scope.

One option would be an LC filter between the powerbank and the scope to cut the ripple. Another would be a 9V battery with a 7805 circuit to regulate down to 5v instead of the powerbank.

My question is, am I right in thinking that the 7805 is the better solution?


texts: I don't understand how a zener diode placed in series with a resistor creates a constant voltage for a load in parallel with the diode. The load voltage drop must be the same as the zener diode voltage drop since they are in parallel, right?


texts: Looking for a high speed, high powered motor

texts:
So I'm trying something that has been attempted before and that is to have an electric turbo charger.

essentially the goal is to spin a compressor wheel (20 grams) at 150k RPMS and sustain it for about 3 - 4 seconds. I've been told I need the power output to be at least 5kw in order to achieve this.

I have the battery system figured out and I'm at the point where I need to find this unicorn of sorts!

Is this even possible? I know Volvo and Audi have electric turbo chargers so there most be something out there right?

Thanks for the help! I'm a bit new to motors in general so explanations would be incredibly welcomed!


texts: Efficient power supply for embedded project

texts:
I'm working on wireless sensor network project consisting of sensors based on ATmega328 and MRF24J40MA. The sensor is expected to stay asleep most of the time, waking up on regular intervals to collect sensor data and sporadically sending collected data over 802.15.4.

I'm not sure on how to power the circuitry for longer life on batteries. I consider two options:

Use LVD1117V33 to scale down 4xAA batteries to 3.3V. I guess this means batteries operational voltage range of 6V..3.3V.

Use NCP1402 to scale up 2xAA or 1xAA to 3.3V. I expect the battery to be drained nearly to its minimum until the circuity fails.

The second option sounds more promising, but don't I overlook something? Are there any options?


texts: Grounding the components of a DIY cnc machine

texts:
I'm in the process of building a DIY cnc machine. It already runs, but I noticed it has some interference problems (steppers act weird on occasions, the full graphic smart controller LCD has trouble displaying the contents), due to the noisy chinese spindle I'm using. To remedy this, I've read I should ground everything in a star-like topology.

The hardware consists of a 12V chinese PSU which connects to an Arduino Mega with Ramps 1.6 and 3 DRV8825 drivers. There is also a spindle controller, which generates the noise and doesn't have the ground symbol. I was told on another forum, that since it doesn't have an earth symbol, I should just tie the earth to one screw of the chassis. The PSU and the spindle controller are connected to an extension socket.

I'm using shielded cable to connect to the stepper motors from Ramps, but the cable is also not grounded yet (just found out it has to be).

Can somebody describe how does a star-like topology look in my case? I've also read, I should ground the motor drivers, but I can't seem to find anything on the internet regarding this.

Thank you.

The 12V PSU:

The spindle controller:

The Arduino Mega/Ramps board and DRV8825 stepper drivers (I know dupont cables and isolation tape should't be used in this case. I'll replace them promptly):

Stepper driver and signal cable connection (the shielded signal cables are not grounded yet):


texts: how to know the rotation direction and pin order When manufacturer is doing SMT

texts:
I want to know about the SMT requirement documents.
what I mean is that

when I make a partlist and XY-coordination data from PCB software.
that shows me rotation angle like R90 or MR270
I know that R90 means rotate it 90 degree and MR270 is mirror and rotate parts.

but I'm curious how to know the direction?
R90 can be either clockwise or counterclockwise?
and I think If the pin position is opposite, so it may cause confusing.

For example, If I make a capacitor which is left to right pin number are 1 and 2.
but other people make a capacitor which is left to right pin number are 2 and 1.
those are opposite way.

In that case How the SMT manufacturer know the direction of parts?

(add one more picture for a question)


texts: SSD1306 Display SPI Connection or I2C (According to resistors)

texts:
I bought one of those cheap 0.96" OLED Displays from china, ebay.
In the product description it states that it's a I2C Display, Ebay Link.
I want to use it with an ATmega8.

I connected it accordingly to the tutorials I found online:

Pin1, GND: GND
Pin2, VCC: VCC (3.3V)
Pin3, D0: Pin28, SCL (Pullup to 5V)
Pin4, D1: Pin27, SDA (Pullup to 5V)
Pin5, RST, PORTB.0
Pin6, DC: PORTB.2
Pin7, CS: PORTB.1

and this is my code (99% the same as on the library's github page):

#define F_CPU 1000000
#include <util/delay.h>
#include <stdint.h>
#include "libs/SSD1306.h"

int main(void){

    DDRB=0xFF;
    DDRC=0xFF;

    PORTB = PORTB & ~(1<<PB0);
    PORTB = PORTB & ~(1<<PB1);
    PORTB = PORTB | (1 << PB0);
    _delay_ms(100);

    // This is our buffer
    // Each byte = 8 pixels on the screen
    uint8_t buffer[1024];

    // Only two lines of code to initiate the driver
    // and to send our framebuffer
    SSD1306 myDisplay;
    PORTB = PORTB | (1 << PB2);
    myDisplay.sendFramebuffer(buffer);

    PORTB = PORTB & ~(1<<PB2);
    // Hardware function to reverse the pixels
    // (swap black and white pixel)
    myDisplay.invert(1);
    // Revert back to normal display
    myDisplay.invert(0);

    return 0;
}

I use (or want to use) this library: Github
Just because I found it and thought it looked nice, could use another as well.

What I checked so far is:

Cable connections are okay and as described above
System clock is 1 MHz
Tested another display

In every case, the display remains dark and black, not even a flickering.

When I looked at the backside of the display, I thought the description is strange (see the attached image).

There is written, that for IIC connection, resistors R1, R4, R6, R7 and R8 would need to be connected, while, in fact, only R3, R4 are connected, what would correspond to SPI connection. Am I misinterpreting something or was the ebay description wrong?

Can anyone help me?
Kind Regards
Me


texts:
In the transmission line theory you can use this circuit to describe a transmission line:

So the resistor and the capacitor form together a low pass. So each cable has to have a cutoff frequency where signals no longer get to the other end of the cable, right?


texts: How does moisture get into silicon chips?

texts:
Many chips have Moisture Sensirivity Level rating (MSL)
I am trying to understand how exactly moisture can get into a silicon packaged chip. Every document I read just states it can, but doesn't say how. E.g. this one from TI:

Once the dry pack bag is opened, moisture from the ambient air gets
into the device. If the floor life is exceeded and too much moisture
gets into the device during reflow, the moisture can expand and damage
the device.

My guesses are:

there are small holes between pins and silicon package where the water molecules can seep in
pins oxidize too much and make room for water to build up inside the outer edges of the chip
silicon is porous and soaks up water

Does anyone have an insight into any of these?


texts: I think the answer is 1 and 2, so option C. But for the circuit to be realized, is the rule that there is a maximum of 1 degree difference between the highest and lowest order terms of the P (s) and Q (s) polynomials?


texts: AC "chopping" power supply inrush current problem

texts:
I've made a simple AC to DC chopping/switching power supply circuit (I'm not sure if it's called that) as shown below. in the left part of circuit (which is the gating/chopping part) when the rectified input voltage gets higher than 20 volts, the Zener diode conducts, transistor turns on and the MOSFET turns off consequently, therefore the maximum voltage on 100uF C3 cap remains at about 20V. the right side of the circuit is a buck converter based on MC34063 based on its typical application.

the circuit works fine when tested on 25v AC input (with no load). I get 5.2volts output capable of providing up to 300mA; but when I connect it to 220v AC line the 33ohm R4 resistor burns and the PCB track along that resistor snaps off immediately, breaking the circuit. any Idea about that??

and here are some information and test results :

the MOSFET Vds-max is 600v, the 100uF C3 Cap is 25v tolerant.
R4 resistor is 1W, Zener diode is 20v 0.5W, the other parts are 1206/0805
in 25v AC input test, the voltage across the C3 remains at 20.5v which is fine. no part got hot
the parts are cheap Chinese ones. but the problem remained through various tests, various PCBs


texts: Three-Phase Thyristor Converter Simulation Question

texts:
I am required to simulate a three-phase full wave thyristor converter using MATLAB Simulink. The circuit I have so far is given below:

The three input sources are 230V each at 50Hz, the first having a phase of 0, the second 120, and the third -120.

The thyristors come with resistance-capacitance snubbers which I eliminated by setting the resistance to infinity. But in doing this I had to add a high-value resistance in parallel to the second thyristor in order to get the circuit to run. For the thyristors:

Thyristor resistance = 0.001 ohms

Thyristor inductance = 0 henry

Forward current = 0V

Snubber resistance = infinity

Snubber capacitance = 1e-12 F

In order to trigger the thyristors at 45 degrees, I have set the frequency to 50Hz (the same as the sources) and the phase delay (seconds) to (1/50)*(45/360).

The output I get is the following:

As you can see, the waveform has been rectified. But I'm looking for the ideal output from a controlled rectifier and this output has several ripples as you can see. I tried several different values for the thyristor parameters, but couldn't change much.

Could anyone tell me what's wrong with the circuit?


texts: charging 12v lead acid battery with OEM charger

texts:
I have an ExpertPower 12V 7 Amp EXP1270 Rechargeable Lead Acid Battery (link on Amazon here) and would like to safely charge it. Do you think this charger (Battery Tender 021-0123 -- link here) is an appropriate option? Based on the specs, it seems that they're compatible but since I don't have a background in electronics, I want to make sure I will not have an explosion in my place.

Thanks!


texts: replacing diode connected BJTs by simple diodes in a current mirror circuit

texts: Why cant we replace diode connected BJTs by simple diodes in a current mirror circuit?


texts: Error sending data to LED Display board from a microcontroller

texts:
I have a LED Display which has a RS232 connector so that we can connect it to our system. Display board accept whatever data we type in hyper terminal and display it. For e.g if I type Hello in terminal, it will display Hello.

Now I have an AVR Devlopment Board. I have programmed the MCU to transmit Hello at delay of 2sec. I have connected the RS232 cable of display board to the AVR development board. It should display the Hello message but its not displaying anything. I have tried including <cr><lf> also because when we hit enter at the hyper terminal, only then it accepts the data. But still not able to display. Any suggestions where I am missing the point?

CODE

void serial_Init()
{
UCSRB = (1<<TXEN) | (1<<RXEN);
UCSRC = (1<<UCSZ1)|(1<<UCSZ0)|(1<<URSEL);
UBRRL = 51;

}
void serial_Tx(char *str)
{
for (unsigned int i=0;str[i]!=0;i++)
{
    UDR=str[i];
    while(!(UCSRA&(1<<UDRE)));

}
}

int main()
{
serial_Init();
while(1)
{

    {

        serial_Tx("HELLO");
        serial_Tx("0x0D");
        serial_Tx("0x0A");
    }

    }

}


texts: What actually is the output current of a boost conveter?

texts:
What I understood at least at a basic level the operation boost converter, the inductor supplies output current when the switch is OFF.

When the switch is ON the the load current is taken current by the output capacitor.

Update
 Is the classification of DCM and CCM is based on the nature output current or nature of inductor current ?

But during switch ON state, the inductor current has nothing to do on the output current ? or what I understood is wrong? Can anybody please explain this ?


texts: How do the TUSB211 USB 2.0 re-drivers work?

texts:
USB 2.0 standard uses bi-directional communication over tightly controlled differential transmission line. The signals are originated from a 90-Ohms controlled driver, and are received with 90-Ohm impedance-controlled receiver. The direction is determined by half-duplex protocol, so there is no collision possible. Signal re-drivers/conditioners are not included into USB 2.0 Specification.

To get the signal conditioned, Texas Instruments offers a new class of devices, USB 2.0 re-driver, TUSB211/214 family. In application diagram, the device sits simply on the top on uninterruped differential transmission line, which apparently shorts both in-out ports of the IC, unless they use the miniscule inductance along the 2-mm long trace. The application diagram (and PCB layout) shows this:

Could someone explain how do they do this?


texts: How to discretize value like EDF ( or other electricity companie )

texts:
I make a solution using some automate like : A9MEM2050 ( Shneider )
( and more advanced, so i have a lot a different value , that include rpm, psi, armonic, etc ...)

Every automate send a value every 10 minutes

Some 'intensive' data:

Some 'extensive' data:

My question is about the discretization ...
I want to display a some chart displaying a value every hours, days, month, years ...

( for simplify the question we only care about the discretisation from 10 minutes to 1hours )

So, simple if data is 'intensive' i make a mean, if data is 'extensif' i return the last value minus the first value ...

But the value at 1:00 is calculate with ( for a 'intensive' ) the value at :
    [00:10, 00:20, 00:30, 00:40, 00:50, 1:OO]
or
    [01:00, 01:10, 01:20, 01:30, 01:40, 01:5O]

Can you provide a RFC / ISO or other Scientific paper on the subject ?

---- Info :
The boss of my companie say :
 - Shneider customer service say, the agregator take a instant value, no Math is done internaly ...
 - 'El-sys GTC' have a option in their firmware and let us the choice
 - 'Carel' no info provide the companie :/


texts: Skin effect - decreasing AC current part

texts:
The image provided by wikipedia (the black marks are mine)

explains clearly the skin effect when AC cirrent increases - the current I increases, thus H increases, and because of lenz law the eddie currents Iw are created such that the magnetic field they create will oppose the increasing H.
I couldnt understand however what happens when the current decreases - I_new is snaller than red I, thus H decreases, and it appears to me that Iwn is in the direction painted in black, therefore in the center of the wire more current flows than close to edges. How come?


texts: PIC18 port b interrupt on change is very sensitive

texts:
I am running a stepper motor with my PIC18F46K80 microcontroller.
This microcontroller offer me the port b interrupt on change feature which basically generates an interrupt if the state the port b input pins is changing.
I use this to watch the quadrature encoder of the stepper motor and ensure the motor is doing all the steps it should do (The encoder offers me two pins which get high and low in some specific pattern if the motor makes a step in a specific direcion).
One big problem I got now is that the port b interrupt on change is very very very sensitive.
Even if I enable interrupt on change only on one pin and connect this pin directly to VDD or VSS the interrupt is sometimes caused if I touch for example the shell of a wire connected to this pin.
For my project this sensitivity and therefore possible disorders are not acceptable.

So I am wondering me which options I have to improve this?
Are there alternatives than the interrupt on change feature to keep track of the encoder signals?
Can I decrease the sensitivity somehow?


texts:
Original Video
[https://youtu.be/d3bF2v056WU?t=1m57s][1]

See pic:
http://i.imgur.com/QgUIyE0.png

Questions about the timing diagram on the right:

G looks like a ramp shape that goes down. Does that mean voltage was a higher constant then went down to a lower one?
What are the boxes containing V1 and V2? If they are voltages why not just horizontal lines?
What are these XXXXX's between those boxes containing V1 and V2?

I've been googling d latch timing diagrams to figure out the above- haven't found it yet but did notice that alot of other d latch timing diagrams look like horizontal lines/box/square wave shapes


texts: Why is \$R_{eq}=0\$ ?and because the \$\tau=\infty\$.so in fact inductor is always in the Transient state and be charged?

texts:
There is a circuit,\$SW1\$ will be closed at \$t=0s,\$and \$SW2\$ will be opened at \$t=10ms\$

simulate this circuit – Schematic created using CircuitLab

Now i know that when \$t<0s\$ and \$t=0^+s\$,the \$i_L(t) =75mA\$,and the book also shows me the \$i_L(t)\$ when  \$10ms >t\ge0\$

\$\tau=\frac{L}{R_{eq}}=\frac{10mH}{0}=\infty\$

so \$i_L(t)=i_L(\infty)+[i_L(0)-i_L(\infty)]e^{-\frac{t}{\tau}}=75mA\$

I have some question about the formulas above

1.Is it because that there is no resistor in the Charging path of inductor,so the \$R_{eq}=0\$ ?

2.\$i_L(t)=i_L(\infty)+[i_L(0)-i_L(\infty)]e^{-\frac{t}{\tau}}=i_L(\infty)(1-e^{-\frac{t}{\tau}})+i_L(0)\$,

and \$\tau=\infty\$,so is the inductor always be charged?

because \$i_L(\infty)(1-e^{-\frac{t}{\tau}})\$ is the  charging formula of inductor,and \$\tau\$,the charging time ,is also \$\infty\$,so theoretically,inductor is always in the Transient state and be charged?

Is my thinking right??


texts: It is accepted practice to maintain lead acid batteries at a float voltage of roughly 2.3 Volts per cell. The precise value depends on battery type and battery chemistry and ambient temperature. We have all done this for decades. Some charger manufacturers use a pulse scheme where they have a comparitor with hysteresis that turns the current off at say 2.3V and on at say 2.2V per cell. This is done at relatively small currents like C/100. I can see that this should represent a energy saving and I know that it is easy to implement by hardware or software. The question is: What is best for the life of the battery?


texts: Crystal oscillator on custom ATMega2560 board is at the wrong frequency

texts:
I have designed a custom board using an ATMega2560. The board works fine when configured to use the internal oscillator. The board stops working when I configure it to use the the external 16MHz crystal oscillator. When I place an o-scope probe at R4, the oscillator measures ~680Hz. What am I doing wrong? I even tried re-soldering the clock chip.

Here is the clock chip:


texts: Can I use diodes as part of a circuit to multiplex several analog signals?

texts:
The micro controller I am using (AVR) only has 1 ADC port, but I have 6 analog peripherals, essentially potentiometers. Since I want to use these 6 different signals on 1 pin, I thought about a design for a multiplexing circuit, but I haven't ever done any analog stuff before, so was wondering if anyone could offer some help.

I was planning on putting an NPN transistor and a diode between the potentiometer and the ADC pin of the microcontroller. I would then use 2 digital I/O pins from the microcontroller to select one of the 6 pots. I was thinking that the diode would prevent any of the current from the active pot going to another pot and thus corrupting the signal. Is that along the right lines?

If it helps, I am only dealing with voltages from +5V to +0V. These signals will not be changing that rapidly either nor do they need to be sampled all that frequently (maybe 10-100 samples per second)


texts:
I made own ESC board.
Here is schematics:

First, I implemented the cycle of 6 combinations of switching signals: A_H, A_L, B_H, B_L, C_H, C_L in loop using delay time before switching to next combination. All as explained here: http://www.edn.com/design/sensors/4407580/Brushless-DC-Motors-Part-II--Control-Principles
And the brushless motor rotates! I'm happy!
No I want to implement combinations switching algorithm using ADC_A, ADC_B, ADC_C and ADC_CENTER signals. I expect to see 60 degree shifted ADC_A, ADC_B and ADC_C while ADC_CENTER is constant. But when I look for that four signals using oscilloscope I see that they are all the same!!! Why? Where is the mistake? In schematic or may be in soldering ( how to check it )? Explain me please!
Schematic is taken from here: https://raw.githubusercontent.com/frank26080115/Frank-Synced-BLDC-ESC/master/circuit/ckt_preview.png
EDIT:
Thanks for Bruce Abbott's explanation.
I found that there is voltage peak at every second step of loop at all ADC lines ( ADC_A, ADC_B, ADC_C, ADC_CENTER ):

It happens at every step when I switch from one Low Side shoulder to another( A_L, B_L, C_L ).
Could it be the reason that the Low side shoulders I drive using simple gpio outputs, not PWM signals?
On steps when I switch High side shoulders that driven by PWM signals there is no any voltage peaks.
EDIT 2:
I found the causes of voltage surges on ADC channels - there is to long delay between switches to next state. The delay is necessary to exclude the probability of opening of the two MOSFET of one phase at the same time. As it turned out, I chose too much delay. Reduce delays and surges missing.


texts: Circuit Analysis of Op-Amp Offset Voltage Tester

texts:
I am reading Understanding Op-Amp Parameters section 11-9. I would like to get my work checked.

My assumptions:

The servo-loop, presumably the op-amp configuration right before V_out, maintains the V_out of DUT at 0V with the virtual earth of -ve input.
The feedback capacitor (10nF) should effectively open-circuit the feedback of the servo-loop.

With the above, I have worked on a numerical analysis to be this:

$$
V_{offset} = \frac{V_{out}}{R_f/R_{os} + 1}
$$
$$
V_{offset} = \frac{V_{out}}{10K/10 +1} \approx \frac{V_{out}}{1000}
$$

I am unsure of my answer, because 10k/10 + 1 is actually 1001, not 1000. It's close but I'd want a very accurate result for this sort of testing circuit? Or perhaps my calculation is wrong somewhere.

Also, if the feedback capacitor is indeed a DC block, what's the point of it?


texts:
I've seen some kind of electronic stethoscope that can capture heart beat rate and filter it with so many other features.

Main oscope of my questoin is about capturing heart sound. There is many ways to detect muscle activities in body. But what is the best way to capture the sound of heart pumping ?

Which kind of sensors are commericaly used ?

PS:A well known commerical kind of what I mentioned is here : thinklabs.com


texts:
I am looking for a Arm development board for a new project I am working on (64 RGB LED POV Globe). POV globe speed questions
I have lots of experience with the Arduino boards but I would like to take a step up to a more powerful board for this project. Also I have been wanting to play with ARM for a while and this seems like a good project to start on.

Requirements

Not insanely expensive, <= $250 preferably
Lots of PWM outputs at lest 10 idealy 24
Program able by the USB port.
32k of chip memory

Nice to have

Ethernet, Not that I would need it for this project but most of my other projects require it.
SD card or other persistent storage, Logging, loading of settings files, ect...

The first board I looked in to was the beagleboard as it has a huge community and lots of resources but it does not appear to have any PWM outputs?

Next I looked in to mbed-NXP-LPC1768 from sparkfun
But from as far as I can tell from the spec it only has 6 PWM pins, and I was looking for more of a complete board with power supply, ect..

My question:

Suggestions on a Arm development board with lots of PWMs?
Am i missing something with the PWMs on the beagleboard? It seems strange that the board would not have any I/O


texts: What is the peak current for CR, LIR and AA batteries?

texts:
I'm working on a project that requires low energy consumption. In standby mode, it will consume about 11uA. However, when it starts working (it will transmit data in RF), the current goes up to 121mA. This is going to happen 4 times a day, and the peak current duration is 2 seconds, at most.

Because of it, I'm searching for a battery (rechargeable or not) that gives me a high autonomy. I'm expecting 1 year of autonomy, at least. However, most batteries datasheets don't give the information about the duration of a peak current, and how much the battery gets discharged for it. I'm looking for batteries like CR2032, LIR2450 and AA types.

Let me give an example: LIR2450 has a nominal capacity of 100mAh. With dc current of 11uA, the autonomy goes for about 9100h. However, if in the middle of the day (all over the week) my circuit requires about 121mA for 2 seconds, how much does the autonomy drop? Is the battery going to be killed by that consumption?


texts:
At what point in host boot process, does a PCIE endpoint get powered ?
Is it powered as soon as the host/PC starts booting or when it starts the enumeration process ?

References would be appreciated.


texts: What is the relationship of the armature voltage and field current and how can this relationship affect the DC shunt Generator?

texts:
This refers to DC Shunt Generator Magnetization Characteristics.
Based on the experiment I conducted, the data shows that the armature voltage is directly proportional to the field current. I think it can also be proved by the formula of induced EMF where E=W/Q. I just don't know how it will affect the DC shunt generator.


texts: Dual switching power supply with centre tap transformer

texts:
I'm making an adjustable power supply, constant voltage/current and all that jazz, and I'm trying to make everything as small and portable as possible, avoiding bulky heatsinks, and using a switching tracking pre-regulator to reduce the overall volume. I read a lot about noise suppression, and I know there'll still be quite a lot of it, but I concluded that SMPS with short/wide AC tracks and other recommended layout considerations followed by a linear regulator would still be more stable than just a SMPS with additional filter (please correct me if i'm wrong).

Anyway, I have a pretty, center-tapped transformer extracted from some old analogue receiver rated at decent power, and I was wondering whether something like this is possible using two switching regulators. The "top" and "bottom" regulator should be able to have different offsets.

The similar questions I stumbled upon online were mostly about connecting ATX PSUs in series, which are fixed voltage supplies using flyback topology, so yeah, no luck there.

If possible, the topology for the positive output regulator would obviously be the buck converter, but what about the bottom one? Can a buck converter sink the current? If not, is there a right combination of topologies to do what I'd like to without meddling with the transformer?

I mean, I guess I could connect the two identical windings in parallel for max power and use buck + inverting for +/-, right? I would like to avoid that because the transformer would get a lot uglier, and I'm afraid I'd mess it up.

PS: Please do not ask me what do I need the stabile voltage for, it is just for fun, and learning about PSU design along the way :P


texts: How to create a circuit which is sensitive to inputs change and results to output change?

texts:
Suppose that we need a circuit with 4 inputs A0-A3 and 1 output out.  when one of the inputs changes (for example 0000 changes to 0001) the output switches to another state. after that for the next input change (for example 0001 to 0010 or any other random state) the output switches to another state again. suppose that the initial state of the circuit is input: 0000 and output: 0.
How to design such circuit?


texts:
I have a portable Bluetooth speaker with a very short play-time on a single charge and I want to know if I can swap the battery for a larger one.
I've disassembled it enough to see that it's driven by a single board that has all the controls, speaker drivers and battery connected to it. The speaker turns on a red L.E.D. when it is charging, but that light does not change/blink/turns off unless you disconnect the charger, so no practical way of knowing how long it actually takes to charge the battery. When the battery discharges, a badly pronounced English message is played through speakers and then the device turns off.
The battery is covered by a shrink wrap so I haven't read its rating yet, however, it is very small, rectangle shaped. Aprox 2 x 3 x 0.4 cm (1 x 0.75 x 0.2 in). It is connected to the board via two cables
I may be able to source a 18650 cell from other devices that failed because of something different than battery, so battery cost is not an issue in this case.
I've seen readily available chip boards for charging Li-ion batteries that only state battery voltage as compatibility parameter. (3.7 v nominal, most cells available are also this voltage). That makes me think that those chips have the logic to charge any battery size as long as it is a 3.7v cell
If that's the case, what should I check in the speaker or in the possible replacement battery to determine whether they are compatible? By compatible I mean the board will be able to charge the new battery and shut itself off before over discharge occurs. The board's power input is a regular USB mini port. (5 volt)


texts:
I have a very simple project that is working off of an external "wall wart" power supply and I would like to add a back up battery in case of power failure.  I have breadboarded a backup power supply with two DC barrel jacks and 2 diodes and it works, supplying the higher of the two voltages.

My question is: do I have to use this circuitry to connect to Vin, ignoring the already in place barrel jack on the Arduino board; or can I eliminate the second of my barrel jacks and diodes and rely on the on-board jack for the wall power and simply take the batteries voltage through my extra jack and diode and then into Vin? I.e., can the Arduino handle power supplies from the on-board jack and Vin simultaneously -- switching back and forth as needed -- or will it just use Vin if it detects an input there?

The Arduino docs don't say this specifically and the question Arduino backup power supply seems to indicate that this is the case, but I just want to ask the question simply and decisively.


texts:
When designing ASICs, engineers may use a wide set of architectural and micro-architectural tools and approaches for management of power consumption of the chip:

Retention registers - registers which have a separate power line and store data while the circuit is not powered
Power domain separations - allows for separation of the circuit into distinct power domains which may be powered off independently of each other
Clock domain separation - allows for separation of the circuit into distinct clock domains with clock frequencies tailored for the required performance and power consumption.
Dynamic voltage scaling - allows for reduction of supply voltage when the chip is in "low load" mode.
Dynamic frequency scaling - allows for reduction of clock frequency when the chip is in "low load" mode.
Dynamic clock gating
Few more

I know that there are FPGAs with clock gating capabilities, and I remember that I read once about FPGA which has retention registers, but are these the only ones?

My general question is: what HW power management capabilities are present in the state of the art FPGAs today? I'm not seeking for explanations of the techniques (though good references are welcome), but just want to be updated on the latest FPGA features.


texts: Need help diagnosing oscilloscope results, newbie question about clock signals

texts:
I'm a newbie, and I don't fully understand the results my oscilloscope is giving me.

I'm attempting to create a crystal oscillator circuit with a square wave. I've already generated a perfect 8MHz wave using a very basic circuit as shown (using a 4001 inverter):

simulate this circuit – Schematic created using CircuitLab

This generates a nice clean signal in yellow:

However when I connect the output to a Schmitt trigger (74HC14), I get the following:

Obviously I have some overshoot issues to deal with on the
[blue] schmitt trigger signal and I think I understand this to some extent (lack of damping circuit), but what is really confusing me is why the yellow clock signal is also messed up? The peaks and troughs align. In my mind, the signals are two different steps/electrical stages, but they are obviously highly correlated. What's going on?


texts: Mini USB receptacle versus proper PCB layout

texts:
While routing my CY7C68013A based PCB I just realized that regular USB B receptacle and mini USB equivalent have D+ and D- effectively swapped.

It seems that the chip was prepared for regular size receptacle (DP is on the left if looking towards the chip), while for mini USB I have to route one of the tracks under the receptacle.

Is it really like this, or did I mess something up? How am I suppose to keep the tracks impedance and length constraints, while one of the tracks needs to go a different way, around the receptacle pads?


texts: Mystery component in Selfie Stick? (iPhone)

texts:
What is the component inside an iPhone selfie stick? Testing reveals it is not a transistor.

We have done some probing of it and come up with the following:

The mystery 3-pinned component drops the phone’s 2.2V microphone line (between pins 1 and 2) to 0.240V when pins 3 and 2 are connected by a push button.

Connecting it to a component tester (LCR-T4) suggests that it is not a common transistor, but 2 diodes (see schematic).

Inserting 2 diodes and a resistor to mimic the component, does not work, suggesting it is something more complicated.

There are no indications on the oscilloscope, of a ‘chirp’ or acknowledgement ( http://david.carne.ca/shuffle_hax/shuffle_remote.html )

Connecting diodes between pins 1 and 2, does not yield a result. (IN4007, BZX553, Bat43, Bat85)

Connecting various Transistors do not work. (30+ from a bag of assorted transistors)

Connecting a plain resistor does not work. (It would if it were Android)

The mystery component inside the £1 selfie stick, is in an SOT416 package. One model had “G9” on the package, another had it scratched off.

Might it be a smart, proprietary chip? If so, how do I get 100pcs (i.e. not cannibalising selfie sticks)

After much researching, probing, experimenting, and asking everyone I know, we are thoroughly stumped! So thank you, in advance, for your time and help.


texts: What is the most efficient 3-phase to single-phase AC transformer for a home grid

texts:
So a friend of mine is getting electrical power installed for an urban site he bought, and I'm just trying to be a good friend by looking into this.
The company doing the installation recommended he go with 3-Phase AC current (230v because this is in the EU) just so that he'd be able to install an all-electric heating unit down the line.
Now, it's obvious 3-phase power is incompatible with the vast majority of household electronics, so he's going to need some sort of transformer hooked-up.

This other question I stumbled upon mentions three different types:
LeBlanc, Scott-T and Open-Delta.

Are any of these the most efficient? As-in, which gives the best conversion percentage and has the lowest idle power-loss.
If not these, is there another you know of?

Thanks you in advance for any valuable insight you can provide.


texts: Distance problems with I2C connection for multiple devices

texts:
I'm considering using the I2C bus protocol to connect up to 100 devices (worst case scenario) to a motherboard to avoid using serial-port connection with each one.

The problems I face are:

I need them to be at a distance as far as 3-5 m
The maximum voltage should be 5V

I've tried to find an answer to the problem and I've come across a couple of solutions such as setting pull-up resistors to counter the increase in capacitance, but I've found mixed opinions and articles and I can't reach a solution.

Do you think this is viable? What other options do I have?


texts: Charging 3 Li-ion batteries in parallel and discharging in series

texts:
I would like to design a circuit that charges 3 Li-Ion batteries in parallel with a 1S charger, then switches the configuration to put them in series to discharge as one 11.1V battery pack. This is quite similar to the design in this answer to a previous post: https://electronics.stackexchange.com/a/219619/152168 (except I'm using 3 cells to power a Jetson TK1, and my switches are a series of relays).

This will be used as a backup battery for a 12V main supply that may occasionally cut out. This is one of my design constraints, I cannot use a different source as my main power. Aside from that, if you have any suggestions for design changes, I'd be happy to hear them.

My first question is whether or not the batteries will fall out of balance when they are discharged is series. The aforementioned old post made no mention to whether or not balance was an issue when switching between configurations. If they do become unbalanced, then I'll have to figure out a separate balance circuit (which I'd prefer to avoid). The cells are all from the same shipment, which I've been told will help them stay balanced. Also, the batteries will never be relied on for longer than 30 minutes at a time, so I will not likely be running them close to low charge.

On another note, I've found that when switching power sources with relays, the Jetson momentarily loses power and shuts down. I plan to avoid that by using some sort of capacitor to temporarily power the Jetson in that moment while the relays are switching contacts. I have very little practical experience with capacitors, so I'm not sure how I would integrate this into the circuit. Could you explain (or show) where the capacitor would go in relation to the batteries, relays, and load? You can refer to the schematic below for an idea of what I want to do. Sorry that it's so messy, I'm new to drawing circuits.

simulate this circuit – Schematic created using CircuitLab

I also don't know what capacitance I will need to keep it running during the switch. I understand the C=Idt/V formula, but I'm not sure how to tell how long is needed. If you wanted to do the calculations yourself, the accepted voltage drop is 2V and the current is about 1A, so C=0.5*dt. How do I determine dt given a particular relay?

If there is a better/easier alternative to relays or any other part of my design, please let me know.

Thank you


texts:
DC/DC Switching Converters: Is it possible to run a current-mode converter in voltage-mode only?
If so, is there an example using a buck converter?
In particular, I'd like to use UC3843 (LT1243) in LTspice as a buck converter in plain-old voltage-mode regulation (disabling current-mode regulation if possible). I've successfully run LT1243 as a SEPIC converter in the past, but I'd like to have run it as a stand-alone buck (step-down) for it's higher efficiency and single winding inductor. I cannot do a flyback (Texas Inst WeBench) for this application.
I apologize if this is a fundamental question. I'm a mechanical engineer by trade and have come a long way learning LTspice, routing PCBs, and programming MCUs. I've tried grounding the Current Sense (SENSE) pin, or changing the compensation, or changing the load type from a resistor to a fixed current load and it always settles at a particular Vout with respect to Vin, as if Vfeedback has no affect.
The UC384X and LT124X chips are current-mode PWM controller legacy chips.
Since I have used this Si7370DP N-channel Mosfet in the SEPIC LT1243 circuit using this UC3843/LT1243 controller, the controller has an internal totem-pole driver. I don't necessarily agree with the responses to this post:
UC3843 buck converter
Thanks in advance!


texts:
I'm working on making improvements to an old project I helped design. The project used an Arduino to take measurements from six sensors to measure the strength of a nearby electromagnet that generated 10 teslas. Now, for this new version, I'm trying to see what kind of improvements that can be done about it hardware-wise based on the feedback from the team.

We previously used the HMC5883L magnetometer for the kit, but we're trying to look into replacing it. For one, it's outdated, and Adafruit doesn't sell it anymore. Another thing, we ran into an issue regarding that sensor. According to the team lead, they had to re-calibrate the sensors every hour because they got saturated due to the strong magnetic field.

After much discussion my team needs a new sensor that won't saturate in that 10 tesla field. Rather, the sensor needs to be stable within two gauss or more (0.2 milli-teslas) and can handle the 10 tesla field. It doesn't have to measure up to 10 teslas, but it has to continue working in that field without any degradation or damage. Most of the magnetometers I seen on Sparkfun and Adafruit seem to be able to measure greater than two gauss, but is it realistic to expect that they can safely operate within 10 teslas, or would it be better to look at individual hall-effect sensors and not these ICs?


texts: how to get a random seed value at that randomize simulation time in SystemVerilog?

texts:
I know 3 EDA companies handle with SVSEED as the below image,

For reproducibility and random stability, I'd like to generate a random value by using "+svseed random" in SystemVerilog Cadence simulation as the below example snippet code,
class const_c;
rand bit [7:0] a;
...
endclass

module test;
...
const_c cons;
cons = new();

initial begin

    for(...) begin
       cons.randomize();
       printf("Current SVSEED: %0d", ?);
    end

end
endmodule

How do we know "svseed" value when "-svseed random" used. it's value in SystemVerilog?


texts:
I feel like this is a true beginners problem, but I fail to see what I am doing wrong here:

I have a SIP switch connected to port A of an Atmega32 and I cannot read correct values from the port. Here is the relevant part of the circuit diagrm:

Now in code, I configure port A as input and activate the internal pullups, however I always read the data word I write to the port when configuring the pullups. Measuring the voltage at the pins with a multimeter I read the correct highs and lows according to the position of the single switches.

The rest of my circuit works, SPI communication and all. Still I reproduced the problem with a minimalist example, what could possibly go wrong here?

#include <avr/io.h>

int main(void)
{
    PORTA = 0xff;
    DDRA = 0xff;
    while(1)
    {
        char bla = PORTA;
    }
}

I cannot rule out, that I have damaged the port, through misconfiguration and the resulting short circuit. So should my next step be to exchange the controller?


texts: Using 3v3 zener, with actual max 3.5v, to protect Raspberry input?

texts:
I'm interested in making a serial connection between an Arduino and a Raspberry.

I'm using a SN74HC14N inverted Schmitt trigger to provide 5V logic from the 3v3 signal. (3v3 TX -> 1A; 1Y->2A; 2Y-> 5V RX)

I'm intending to use a 3v3 Zener (BZX55C3V3) in series with 220ohm to provide 3v3 level to the Raspberry RX, but it gives me 3.5V (which is the max Vz in the datasheet).

Would this be a safe Zener to use, or should I buy a 3.0V Zener (max 3.2V) instead?


texts: Calculating Characteristic Impedance of Jumper Wire

texts:
I'm conducting a test of the LTC490 driver/receiver (http://www.analog.com/media/en/technical-documentation/data-sheets/490fb.pdf), using a small incremental encoder.

I'll make the connections using jumper wires. In this case, is it necessary to use a terminating resistor - I would imagine the resistance of a jumper wire of a small distance is negligible? Nevertheless, how would I go about calculating the characteristic impedance of a wire, given length and thickness?

Side Note: Some of the wiring diagrams include a capacitor between the two lines. What is its purpose, and when is it necessary to use one?


texts: clock oscillator substitution, jitter question (audio DAC)

texts:
I need a 5 x 7 mm HCMOS clock oscillator for my hifi audio DAC (Texas Instruments PCM5122)

I used to employ the following oscillator: FXO-HC736R-22.5792, but it is now discontinued, and the suggested replacement is currently not available from my preferred distributor (Mouser).

I think I may be able to substitute it with one of these:

KC7050K22.5792C1GE00
C3391-22.5792
DSC1001CI2-022.5792T

but I'm not able to compare the specs related to jitter/phase noise.
Can anyone help me understand how these replacements could perform, compared to the "original"?


texts: How to make rgb LED strip digitally addressable

texts:
I'm planning to install rgb LEDs srip on each steps of stair, there are total of 19 steps and I want to control each strip individually so I need 3 for rgb and 19  for each strip that makes 57 pwn signals so instead I want to make circuit for each strip and control all strips with 1 or 2 control signals from arduino something like ws2812. Any suggestions?

P.s led strip is 12v, currently I'm using n channel power mosfet in switching mode


texts: Can you use different Voltage and Amps to a charge phone?

texts:
If I buy a solar panel that outputs 18 Volts and between 250-300 mili-Amps will it charge my phone? I looked at the charger output for my phone and it is 5 Volts and 1 Amp.
I know that Power (units in Watts) = Voltage X Amps.
So if
18 Volts X 250 mA = 4.5 Watts (for solar panel)and
5 Volts X 1 Amp = 5 Watts (for wall charger)
would my phone charge because you get roughly the same Wattage or does it have to what the charger output says?
If I use 18 Volts and 250 mA will my phone get fried?
Thank you, I am learning electricity


texts: Negative air ionizer with a electric net of 3X 230V AC

texts:
I want to make the following negative air ionizer but the following instrucable uses a net of  230V AC + N.
My question is : If I make the following circuit but power it with the two phases of a 3x230V AC (thus 230V AC)

http://www.instructables.com/id/How-to-Make-a-Negative-Ion-air-ionizer/

Will it still produce negative ionized air?
If not can I modify the circuit and how to do so with my current net?


texts:
Okay I got a question on how to design a full wave rectifier circuit.Okay I just read a text-book of malvino's principles on electronic and devices.

Let me tell you I have an input voltage of 64 volts peak to peak (sinusoidal +34 to -34) and a load resistance of 1000 ohms.

The author told to assume Vrip as one-tenth of Vpeak and given following equations in designing a rectifier circuit

Vrip = Vpeak/10 , Vdc = Vpeak-Vrip/2, Idc=Vdc/load resistance and C=Idc/(f*Vrip)

On solving the above equations

I got Vrip=3.4,Vdc = 32.3, Idc = 32.3 milli amps and C=79.1 micro farad

and I have seen a equation peak to peak ripple voltage Vrip = Vdc/(2*f*C*load-resistance)

I have seen outputs for various values of capacitors and resistors. Kindly go through these pictures

In the first pic as you see, the peak to peak ripple voltage is 17 volts but If I substitute those values in the Vrip=Vdc/(2*f*c*R) it gives 1.5 volts. So the question is why does not the formula apply here?

In the second case, I have increased my capacitance but still the peak to peak is at 16.5 volts and I have expected the ripple voltage will be greatly reduced but it does not seem to work and as for the equation Vrip is inversely proportional to the capacitor but there is no interesting change can be seen.

In the last case, I have increased my load resistance greatly but the peak to peak ripple voltage is still at 17 volts.

So the question is Why does not the peak to peak ripple voltage vary according to the Vrip = Vdc/(2*f*C*R) equation and also please let me know assuming the Vrip as one-tenth of Vpeak. Is it a good idea? and I was expecting Vrip that is the positive peak must be 34 + 3.4 and the negative peak must be around +34 - 3.4 but Surprisngly the negative peak voltage is 16 volts.

Please kindly let me know why does not Vripple equation is not satisfied even though i increased the R and C values? and also kindly provide me some good links to understand it more better and also the guidlines on how to design a rectifier circuit to the optimum.Thanks

Update

This is my actual circuit.


texts: I2C bus stopped working when power was switched to battery

texts:
Let me try to describe my schema:

There is 12V acid battery constantly charged with DC 13.8v 500ma, on that power (battery) is connected attiny85 thru 78l33 voltage regulator + capacitor 470uf,

thru 7805 is powered ESP32 (it have own voltage regulator to 3.3v) with capacitor with same value.
Devices communicate over I2C with 10K pullup resistors to 3.3V on attiny side. Wires are few inches long.

Everything works fine when there is external(charging) voltage, when I disconnect it, I2C bus stop working. I haven't trying to lower pullups or connect them on other side - ESP32 . I do not see the reason why that stop working when was powered on battery. (guess my knowledge is not enough :) )


texts:
I've recently purchased SparkFun's starter arduino kit, which comes with a 4-legged RGB LED.  If I understand correctly, this RGB LED should be able to access the full range of RGB colors, with 255 values on each red, green, and blue.

I've wired up my arduino+breadboard with 330 ohm resistors inbetween power and each of the LEDs (I know, the red needs a bigger resistor.  Sparkfun only gave me 330 ohm...).  I've written a program that gives me three slider inputs, so that I can easily choose the 0-255 value for each LED.  Programmatically this seems to work fine, but I'm having some trouble with the actual output to the LED.

It seems that both red and blue only have two settings available - on and off.  As soon as I pass 150 for each color it turns on, anything below that and it is off.  Moving the value beween 150 and 255 does not change the intensity of the color - it stays exactly the same.

The odd thing, is that the intensity works perfectly for green.  Starting at 0, as I increase the intensity slider the green gets brighter and brighter.

Why do my red and blue colors not work the same as the green slider?

Update 1:
I apologize for my ignorance.  I don't know what a PWM is.  The code is written in Node.js, and utilizes duino for interacting with the board.  You can view my code on github.

Update 2:
I switched the power inputs for blue and green, and sure enough the blue now works correctly while the green does not.  Still not sure what this means - I will continue to double and triple check that my resistors are snug, but I'm not sure what else.  Sorry for my illiteracy in electronics.


texts: Joule Thief - operation and the 'supercharged' version

texts:
I've made a joule thief, and it works fairly well, but not as well as I would like.

It's powering a 3.2v LED from a 1.2v battery, but it's very dim. I'm hoping increasing the voltage from the JT will improve it, but I'm not sure how to increase the duty cycle of the transistor. In fact, I'm not actually sure what's making the transistor turn OFF - apparently the toroid core saturates and somehow switches it off, but I don't really understand WHY that would happen.

I've also tried the "supercharged" version that's apparently almost 30% more efficient, but the only difference seems to be that the LED is dimmer.

From http://rustybolt.info/wordpress/?p=221


texts:
I'm building a circuit where a supercapacitor will be charged over wireless energy transfer (basically two coils near each other). This means I can not guarantee the voltage feeding the supercap is within the capacitor's limits, so I have to make a circuit which protects the supercap against dangerously high voltages.

I'm planning on using an op-amp which compares the capacitor's voltage against a voltage reference from a zener diode, which disconnects the supercap from the coil when reaching a limit though a P-type MOSFET.

The op-amp (which is a rail-to-rail type) has its positive supply connected before the MOSFET, to make sure the OP can have a high enough output to completely close the MOSFET. I've also chosen a MOSFET with a high enough turn-on voltage so that the MOSFET will close it even though the op-amp will not quite reach the source voltage. I've included a 1 mF cap (C2) before the MOSFET to smooth out the supply to the op-amp. What do you guys think about the circuit? Will it work?


texts: Vias in a the layout of a CMOS Integrated Circuit

texts:
Is there a downside to using maximum possible VIAs (adhering to DRC rules) to connect two very long metals (ex. Power rails in Mx and Mx+1) running in parallel at block level? I know that multiple VIAs are preferred over a single via for current sensitive connections and that redundant VIAs increase reliability, but, is there something called excess VIAs?

I see a lot of you sharing their thoughts on PCB layout whereas I was looking for answer in an CMOS IC chip layout.


texts:
Chinese BLDC motor from "Cloudrive-tech",
When phases (P1, P2, P3) excited, the hall sensors (H1, H2, H3) give the following reading sequence for CW direction:

FLH => 100(4)
HLF => 101(5)
HFL => 011(3) // Should be 001(1)
FHL => 011(3)
LHF => 010(2)
LFH => 110(6)

Where (F=Float, L=Low, H=High)
In step 3, fine turning the axe by hand under low PWM, alternates between the settled reading (3) and the expected reading (1), elsewhere it settles to the wrong value (3).
For that I altered the control firmware from simple look-up table assignment, to this:
void BM60L300V3_Commutate(void)
{
    uint8_t i;

    // Read H1:H2:H3..
    i = (uint8_t)(Status.DIReg & 0x07); // 1st 3 bits..

    // Previous value error tweak..
    if(i == 3)
    {
        if(STATE_IS_SET(SB_CCW)) // CCW..
        {
            if(BM60L300V3_SensorPrevVal == 3) // Check previous value.
            {
                i = 1;
            }
        }
        else // CW..
        {
            if(BM60L300V3_SensorPrevVal == 5) // Check previous value.
            {
                i = 1;
            }
        }
    }
    BM60L300V3_SensorPrevVal = i; // Update previous value.

    // Output..
    POUT_PORT = POutCrnt[i];
}

And it successfully commutates
It's not my 1st time with sensor-based BLDC control, & I didn't face such issue before,
Do I miss something!
Notes:

I emailed the company with no answer!
After PWM > 40% approximately, there are rotational lags & sensor reading stretching on oscilloscope.

Update: In the firmware, there's a diagnostic mode which I use to identify the correct wiring, measurements and so. In this mode I set the phase output and read back the corresponding hall sensor readings. F => the phase is OFF, H => The phase is V+, L => The phase is GND.
The motor specifications:


texts: Confusion with NPN input wiring to a converter

texts:
I have this frequency to analogue signal converter and I'm very confused about using it with NPN inputs.

Here is the only block diagram they provide in their manual:

When I power this converter before wiring any input, I measure around 15V between Y1 and Y0 also 15V between Y2 and Y0.

So here is how I wire a switching device to the converter:

When I wire like above and measure the voltage at Y1 by scope I see a pulse with low 5V and high 15V.

I didn't use Y2 at all. And some of the devices I need to hook up will output 0-5V pulse trains. I'm confused ad this point how to use NPN input here for a generic pulse input.

Is my wiring correct? How should it be used if the device already has pulse output? Should I use a transistor to use NPN input? A diagram would help a lot.

EDIT:

Here how I interface:

The only thing I dont know when the transistor is ON, Y1 is directly grounded and how much current can flow. What I dont know is the output impedance the value of R4. I made a test and when I measure Y1 this way scope shows 0-10V pulses at the point Y1 so I adjusted R4 in simulation to have the same result. I didnt get any malfunction besides the ripple in analogue output of the converter. WHat do you think about my interface in my edit?


texts:
I am designing a boost converter for wind turbin, with load 12Vdc, 2A.
Before I install my boost converter on my windturbin, I putt a test to make sure it work properly. So I use this circuit to simulate

the battery represent power supply and I use tip142 as the gate driver.
with no load circuit, the boost converter is working. but when I add load, like the circuit bellow

it's not working, there's no boost effect measured. power supply work in current mode in low voltage.
Is it because the gate driver? Do I really have to use bootstrap? or something else?

Thanks,


texts:
I am working for a small project which involves me to communicate between an Atmega and Beaglebone black through I2C.

My question is that Atmega has an 8 bit microprocessor and beaglebone black has a 32 bit microprocessor. Is it possible to establish I2C between them?
I mean will there be any problems communicating with two devices who process at different speeds?

Also, Beaglebone uses SMbus functions for communication and AVR uses traditional I2C functions. How do I change the traditional AVR I2C commands to work with the beaglebone black or is it possible that I change the Beaglebone's SMBus functions to work with AVR?


texts: Can not find or calculate ampere hour from the data sheet

texts:
Here is the data sheet of a ups:

http://www.ups-service.by/PDF/Technical_Specification_PowerWave_60-500kW_English.pdf

How long for a nominal 500A current drawing load would this utility last?
How can I calculate it?
Couldnt find from the technical datasheet.


texts:
I would like to generate a biasing voltage of around ~300-500V. The load is small, less than 1mA (i.e., ~1W power transfer). Input is 30V DC, so I need a 10x voltage amplification. Normally, given I don't need much efficiency nor do I care about ripple too much, I'd go for a series of voltage doublers built with discrete components.

But I'm a lazy engineer and I like simpler, smaller solutions that can be implemented quickly. As such, I'm looking to see if there's a component that can do this pumping for me. A dig through the electronics retailers shows that such components exist - but are limited in their output voltage to about 12V or so - presumably for the more usual requirement of biasing a communications line or something. The best I have found is this Linear 3482 or 8331, but these top out at 90/100V, and, from their relatively high transfer powers and conventional regulator topologies, seem to be the "wrong kind" of pump for me.

Part of me thinks that what I'm looking for is too specialised, and ICs that output this kind of voltage don't exist (if nothing else, because the separation of their pins would need to start being quite large!). This part of me says that the best I can hope for is a driver IC, to control a discretely-implemented Dickerson or Bootstrap CP.

But the other part of me says that this isn't an usual thing - camera flashes, for example, routinely require biasing this high (or used to!) - and so commercial solutions should exist. This part of me thinks I'm looking in the wrong places or using the wrong keywords for my sought-after part.

Do you know of any integrated charge pump or voltage regulators that can output ≥300V biasing voltages?


texts: Adding/Subtracting in binary and hexadecimal formats?

texts:
I have two numbers(in decimal):

M = 3892.74
N = 9341.65

I am trying to add and subtract them in binary numbers and then in hexadecimal numbers. I manage to convert the numbers into binary/ hexadecimal with 4 fraction digits.

M = 111100110100.1011   and M = f34.bd70
N = 10010001111101.1010 and N = 247d.a666

and I have found M + N = 13234.51 = 11001110110010.0101 = 33b2.83d6
  I am having trouble doing the M - N ? Is there negative numbers in alternate number systems and how would I carry out this subtraction ? If my earlier work can be verified, I would also appreciate it. Thanks


texts: First two byte of Transmit Buffer sent by STM32 to Motor Controller is transferred wrong

texts:
I want to use STM32F407VET6 board to send commands to Roboteq Motor Controller MDC2230 and I'm very newbie in embedded systems.

Firstly, I created my project via STM32CubeMX and connected RX and TX to each other. The loop-back worked correctly.

Also I can create communication between my PC and controller via RS232 to USB Converter. If I send "get Left Motor Speed" command via CuteCom, (It's: "?$03 1") Motor controller responds to PC without distortion successfully.

And also STM32 communicates with PC via that converter cable, sends and receives data correctly: I can see outputs of STM32 on CuteCom and can send commands to STM32.

At last, I connected controller to micro-controller. Here is the connection:

+--------------+        +-------------------+      +-------------------+
| "STM32"   TX |------->| R1OUT        R1IN |<-----| DATA OUT (Pin 2)  |
| "USART2"  RX |<-------| T1IN        T1OUT |----->| DATA IN (Pin 3)   |
|          GND |--------| GND           GND |------| GND               |
|         3.3V |--------| 3V-5.5V "MAX3232" |      | "Roboteq MDC2230" |
+--------------+        +-------------------+      +-------------------+

But in the case of STM32 to Roboteq Controller; STM32 sends first two bytes of buffer, wrong. It must be:

( 3f 24 30 33 20 31 0d ) "?$03 1\r" , but CuteCom(*) shows:

( bf 27 30 33 20 31 0d ) "¿'03 1\r" and sometimes(**):

( bf 27 38 33 20 31 0d ) "¿'83 1\r"

Here is some parts of code which works in other cases but not in above connection:

...

#define MAX_COMMAND_STR_SIZE 32
uint8_t tx_buff[MAX_COMMAND_STR_SIZE];
uint8_t rx_buff[MAX_COMMAND_STR_SIZE];
memset(tx_buff, 0x00, MAX_COMMAND_STR_SIZE * sizeof(uint8_t));
memset(rx_buff, 0x5F, MAX_COMMAND_STR_SIZE * sizeof(uint8_t));

...

sprintf((char*)tx_buff, "?$03 1\r");
while ( 1 )
    {
        dummyInit(&huart2);
        HAL_DMA_Init(&hdma_usart2_tx); // FIXME: Is needed?
        HAL_DMA_Init(&hdma_usart2_rx); // FIXME: Is needed?
        HAL_UART_Transmit_DMA ( &huart2, tx_buff, strlen((char*)tx_buff) );
        HAL_Delay ( 10 );
        HAL_UART_Receive_DMA ( &huart2, rx_buff, MAX_COMMAND_STR_SIZE );

        if ( DEBUG ) printf("tx_buff: %s\n", tx_buff);
        if ( DEBUG ) printf("rx_buff: %s\n", rx_buff);
        if ( DEBUG ) printf ( "DR: %"PRIu32"\n", huart2.Instance->DR );
        if ( DEBUG ) printf ( "ERR: %"PRIu32"\n\n", huart2.ErrorCode );
        //printf("Returned --> %d \n\n", getSpeedL(FALSE));
}

...

void dummyInit(UART_HandleTypeDef *_huart) // FIXME: if any other way exists, replace with this
{
    __HAL_UART_DISABLE(_huart);

    CLEAR_BIT(_huart->Instance->CR2, (USART_CR2_LINEN | USART_CR2_CLKEN));
    CLEAR_BIT(_huart->Instance->CR3, (USART_CR3_SCEN | USART_CR3_HDSEL | USART_CR3_IREN));

    __HAL_UART_FLUSH_DRREGISTER(_huart);

    /* Enable the peripheral */
    __HAL_UART_ENABLE(_huart);

    /* Initialize the UART state */
    _huart->ErrorCode = HAL_UART_ERROR_NONE;
    __HAL_UART_RESET_HANDLE_STATE (_huart);
    _huart->gState = HAL_UART_STATE_READY;
    _huart->RxState = HAL_UART_STATE_READY;
    _huart->RxXferCount = 0;
    _huart->TxXferCount = 0;
}

(*) I'm using some lazy way to read communication between max3232's T1OUT and Roboteq's DATA IN pin. My RS232 to USB converter connected to my pc, and there is M-F Jumper cable on RS232 side. I'm just touching to T1OUT of MAX232.

(**) And CuteCom shows output with noise.

What are the wrong parts of my approach? I know, my first fault is being a Software Engineer, not an Electrical Engineer.


texts: Design of output stage for CNY70 reflective sensor

texts:
I have built the following circuit for a reflective sensor:

The resistor \$R_D\$ has been given the value 200 \$\Omega\$ and the resistor \$R_T\$ is to be dimensioned. \$V_{CC}\$ is 5 V.
I have examined the datasheet and for my application the CTR for the CNY70 will be 5%, and the \$I_{C,rel}\$ will be about 1, when the forward current through the diode is 20 mA.
I have used the following equation to calculate a resistor value for \$R_T\$, so that the output voltage \$V_{out}\$ over \$R_T\$ will be close to 5 volts when the infrared light emitted by the diode is reflected and captured by the phototransistor, and close to 0 volts when the infrared light is absorbed by the surface:
\$V_{out} = I_F * CTR * I_{C,rel} * R_T\$
which in this case gives a resistor value of \$R_T = 5 k\Omega\$ when setting \$V_{out} = 5\$ V.
When setting up the practical circuit, the output voltage is nowhere near the 5 volts, but peaks at about 1.7 V at maximum reflection. This makes me wonder whether the equation i used is correct.
Out of curiosity, I tried using a resistor value of \$R_T = 56 k\Omega\$, where \$V_{out} = 1.5 V\$ at minimum, and \$V_{out} = 5 V\$ at maximum reflection, which is fine, as I am using a Schmitt Trigger to discard voltages under a certain level and amplify voltages over a certain level to 5 V's.
What is wrong with my equation? Sorry, if i left some important details out. I'm pretty new in this field. Feel free to ask further questions.


texts: Understanding High Side Current Sense OpAmp Datasheet

texts:
I'm considering the INA199A3, AD8293G80 or TS1102-100 (decreasing cost order) for a high-side current sensing application. According to my understanding the output voltage error is mainly affected by the input offset voltage Vos and gain error. Obviously the lower offset voltage and gain error, the better. In regard to the typical characteristics the TS1102 (Vos=50uV) clearly loses to the INA199A3 (Vos=5uV) and AD8293G80 (Vos=9uV).

What I'm stuggling with are the maximum Vos values of INA199A3 (Vos,max=150uV), AD8293G80 (Vos,max=50uV) and TS1102 (Vos,max=200uV). Seemingly when considering these worst-case ratings, the INA199A3 which is supposed to work well down to 10mV full-scale sense voltage according to the datasheet isn't much better than the cheap TS1102. Also no Vos-historgram is given for the INA199 which leaves me wondering what figure one is supposed to use.

Also, suppose I hit a part with large Vos, how would I compensate it?


texts:
I would appreciate some help solving this simple circuit which I'm trying for some time but can't seem to match with the given answer.
Aim is to find output voltage \$V_o\$

for the given input voltage -

My attempt : Since the only current flow \$i\$ is from \$V_O\$ to ground via 4k and 1k resistors, and \$V_+=V_{in}\$ $$i(mA)=V_{in}/1$$
$$\Rightarrow V_o=V_{in}+i*4=5V_{in}$$
So that when \$V_{in}\$ vary from (-5 to -2); (-2 to 2); (2 to 5)., \$V_o\$ saturates at -10; varies linearly to 10; then saturates at 10.
But the output is given as -

Thanks,


texts: Does USB-A connector have the pins required for USB power delivery (PD)?

texts:
I have looked at various USB power delivery (PD) adapters that supply a certain number of watts and are powered by 230V mains voltage. Always, they seem to have either a USB-C port or a full USB-C cable permanently connected to the adapter. I have never seen a USB power delivery adapter with USB-A port, so that one could use it with USB-A to USB-C cable.

Does a USB-A connector even have the pins required for negotiating power delivery (PD)? I know it can supply at least 5V voltage, but I'm not interested in that; I'm interested in power delivery standard with much higher voltages.

Wikipedia says a PD aware cable needs to be used. Can a USB-A to USB-C cable even be PD aware? If it can, is it possible in practice to find such PD aware cables in the marketplace?


texts: How would I connect an HC-06 bluetooth module to an SN75176A RS-485/422 transceiver?

texts: I am trying to fashion a small module that would allow me to connect to an RS-485 system via Bluetooth. I have found that the potentially cheapest solution would involve an HC-06 TTL Bluetooth transceiver and an SN75176A RS-485/422 driver. However, in order to prevent echo on the BT side of things, I would need to somehow detect a signal coming from the HC-06 and use it to power both the R̅E̅ and DE pins, which would otherwise be held low. The HC-06 does not provide such a pin, having only Vcc, GND, RX, and TX. How can I interconnect these two devices?


texts:
I've got an SM941 SSD and it became dead after shutdown while writing data.
I decided to use up the nand flashes on it to DIY a new SSD.

Then I get an controller board(SM2246EN) with NGFF size, SATA interface, and I successfully resoldered the flashes onto that board. After using MP tool, I get a brand new SSD with nearly full SATA3 speed(550MB/s).

But the problem occurs, when I'm writing a lot of data to the SSD, the SSD becomes extremely hot, maximum temperature of 120C is detected after writing full 256GB data. When I'm reading, the temperature is still too high, about 80C after one 256GB cycle. It's not a sensor problem since it's really extremely hot when I put my finger on the controller, and my red thermometer do shows that it's about 110C on the package of the controller.

I've put it on to the test, for several times, writing and verifying the disk with no errors. So it seemed the temperature doesn't cause any problem.

But I still concerned about it, is it really normal for a controller to have a die temperature about 120C?


texts: Limiting input voltage for buck converter

texts:
I want to power some micro controllers and a couple of leds on my electric bike, counting up towards 5 Amps.

Power supply is a 36V battery, with a range of about 42V to 33V. This voltage is to be brought back to 7V for LEDs and then further down to 5V with a LM317 for Attinies, Arduino and SIM 800.

Most of the buck converters I come accross are rated up to 40V. So with a full battery I exceed this value. I have mounted some five bucks now and they got all fried, I'm affraid.

Edit: the schematis of a LM2596 (which most of the blown ones were) typical usage:

I see 2 possible solutions, and ask you guys please to consider what to do (or add a much better idea!):

Limit the input voltage by a divider
Replace capacitors (and inductor) on the boards

@1: Which power rating the resistors should have to make sure these 5 amps are available for the buck? How to prevent an enormous draw from battery?

@2: Does anybody have any idea on whether this is doable at all? If I look at the datasheet of TI LM 2596; caps and coil are critical choices for eventual power of the design. Messing around with the original ones might get me into trouble?

Thnx for any direction in this, and please bare with me since I'm quitte novice in all this.


texts:
Small, permanent magnet, brushed tri-phase DC motors ('toy motors') may give a speed/torque curve, or at minimum a no load RPM.  What is typical RPM accuracy relative to the datasheet, and how precise is its RPM (i.e. its variation) from run to run?  Moreover what variables affect this accuracy/precision?

I have not gotten to the point of measuring RPMs with a tachometer or encoder, but get the sense that even under no-load, forces from gravity affect the speed/current consumption when the motor is positioned in different angles or moved with acceleration.  Beyond external forces, it seems like manufacturing variances in coil turning, permanent magnet strength as well as inconsistent contact between the brushes and commutator could all cause RPM inconsistencies for a given voltage/current.  I took apart a Mabuchi 130-form factor motor and manually counted the same number of windings (70, specifically) on each armature, which was good to see.  However, I expect that I will need to implement closed-loop control to achieve constant RPM.


texts:
I'm currently having trouble with my relay, and I suspect it's a problem with my setup. Here's how I have it setup.

I have a raspberry pi 3 B. I want to power something using the 5V output, so I have bought this relay.

Right now I have the relay powered to

VCC -> 5V  / GPIO 2

GND -> GND / GPIO 39

SIG -> pin 7 /GPIO 4

I know the relay is powered since the D0 light has turned blue to indicate it is on.

I am running a python program to power HIGH GPIO 4 for 5 seconds, then LOW for 5, and loop.

I have a bubble machine that I'm trying to power from the raspberry pi, and have tested it's red line & GND line is working by hooking it up straight to the Raspberry PI directly and it turning on.

So, even if I have gotten the low/high trigger wrong, I know that the power should turn on eventually.

Here's my problem. When running the python script, I hear the "click" of the system, and a red light turn on. No matter what though, I never get any voltage when I hook the power line of the bubble machine to the outputs (shown on photo). I have tried just tapping it with the metal end on the wire for all 3, I have un screwed and rescrewed it into the openings, and even tried tapping the wire to the soldered points on the bottom.

What am I doing wrong? Which of the three points should I be expecting to send out 5V for the machine? Am I assuming correctly that it will output 5V?

Thanks!


texts: Reference pin current of part in LT spice netlist

texts:
If I want to reference a pin current in LT spice, I can do so in the graph as shown in pink below (used for calculating total power of a part).
V(Vc)*Ix(U1:Vc)+V(FB)*I[1]x(U1:FB)+V(SW)*Ix(U1:SW)+V(N003)*Ix(U1:Vin)

If I want to do so in a b-source, I can't
V=V(SW)*Ix(U1:SW)

throws an exception upon 'compiling'
However, if you throw in a resistor, you can reference the current through a part with a singular current in a b-source, so I add small resistor.
V=V(SW)*I(R6)

I don't like adding extra resistors all over in my simulations.
Is there any way to reference the pin current of a part without using resistor?
[]


texts: layout transfer to epoxy resin via UV light

texts:
I have an epoxy resin PCB board, inkjet transparent film, photo resist developer (Natriumhydroxid), and UV box. I printed the circuit layout onto the transparent film and cleaned the PCB's surface.

Can I directly expose the UV light to the cleaned epoxy resin to transfer the layout or do I need to do something before it? I am watching or reading instructions and they all use photopositive PCB. I would very appreciate if someone explain me what steps do I need to apply to epoxy resin? Lastly, when do I apply to photo resist developer?


texts: How can I reduce the number of microprocessor pins I need to use?

texts:
In my circuit, 5 choices are made by the user through jumper.
Please look at the picture:

I have to use 5 pins of microcontroller in this method.
How can I reduce this number of pins?
Is there a component for this job, or any other posdibilities?


texts:
Circuit primitive in CircuitJS

First, I'm having a hard time with transistors, and only recently managed to pass current through a NPN as planned (70-ish mA from 5 V with a 325 hFE 2N3904 with a 10K Ohms to the base).

Second, I'm using a ESP8266 devboard, which can only pass 40-ish mA through its GPIO pins, and a Songle relay that needs 70 mA at the coil according to the specs.

I have 3.3 V from my breadboard power supply going to the rail, then to the MCU Vin, and again from the rail to the relay's coil, and the other side of the coil to the NPN's collector; the emitter is connected to the ground rail, as is the MCU.  The base is connected to a GPIO, via a 10K resistor; the hFE is 325.

Everything is powered from the same battery, so is at the same potential (I used to try while the MCU was connected to USB, but I wasn't sure if this was a problem or not).

I cannot get the relay to click, or even a LED to light.

If someone could walk me through the math, and tell me what I'm doing wrong, I'd greatly appreciate.  Transistors were pushed to me as "simple", and "like a switch", but it's neither to me, and the simple fact there's also PNP transistors kinda makes me want to cry.

Again, any help would be dearly appreciated.  I would post a picture of the setup, but there's a lot of stuff on the breadboard, and I'm not sure it'd be clear, but do let me know if it would be necessary.

[Picture added]


texts:
Suppose I have multiple dataloggers receiving sensor data, how can I sync those signals afterwards? The most obvious way would be adding timestamps to the data, but they have independant clocks, so I can't really sync the signals, even with those timestamps.

Would it be possible to use a small satelite time chip for this, so that the stamps all come from the same source? Or how would you solve this?


texts: Having two different ground planes on the same layer Eagle

texts:
I am designing a PCB with Eagle in order to use the LMZ31503 voltage regulator from TI. This IC uses two ground planes, one called AGND and the other one called PGND for power routes. I linked PGND to the GND and am trying to isolate AGND and then somehow linked it at one point to PGND. However, I can't manage to have the two planes isolated from each other when I use polygons with the adequate names followed by the ratsnest function. They fuse together. Is there anyway I can keep them isolated. I have also tried using the ranking and "isolate" properties without significant results.
Thank you for your help!


texts: What is the function of diode and capacitor in RS232 shifter circuit?

texts: as shown in the picture, can anyone explain the capacitor and diode in detail? Thank you!


texts:
I was wondering if anybody could suggest some common items around the house or at the hardware store that would make a passable core for an inductor. Or items that I could salvage material from. For example, maybe bundling together a bunch of nails could work? Maybe old radios or something are a good source?

I’m trying to make a loopstick antenna, so I need a rod shaped core for that and I’d rather not just order one on the internet.


texts: I have a RS232 to TTL Converter which has 4 pins Vcc, Tx, Rx, GND . I am trying to make a serial communication with my PC. I have a AVR development board and I have tested my program by connecting UART to USB cable to development board and my PC and is working. But when I connect jumper wires tx to rx of and rx to tx of converter and vcc to 5v and gnd to gnd then it wont work. I dont know where is the problem. Is my converter has some problem. Please help


texts: DIY Servo arm using wrong inverse kinematics doesn't make a straight line

texts:
I have built a Servo-Arms with HS-422 servo (super simple basic servo motors found in a starter kit) that gets angle values with inverse kinematics in Processing (java).
The inverse kinematic (on computer) is ok and it is based on this
The communication with arduino is ok, in the sense that if I put the 2 servos at 0°-0°, 90°-90°, 180°-180° the arms go in the right position.
BUT if I draw a straight line in my java sketches... the 2servo-arms draw.. a kind of weird 'U'.
Code of Inverse kinematics is here.
But I think it is right and there is some structural-mechanic problem I can't understand.
Someone can advice me something?
EDIT:
resolved! there were some problems, caused by wrong inverse kinematic. both comment and answer was usefull, thanks to this powerful community!


texts: transmitting 5v signal over a long cable

texts:
I'm seeking for help here as I need a reliable answer to this. I need to get an input signal (low frequency 5v digital pulse), to a micro-controller from a (proximity) sensor situated in a distance from the control board.

I'll itemize the important points.

Max Tx distance : 50 m
Max digital pulse frequency : 10 Hz
Voltage range of the sensor : 5 to 30 v (it outputs the same voltage as supplied)
Max input to micro-controller : 5 v

For a simple, similar application, this is what I've done before; the sensor is supplied with 12 v. At the other end, the pulse (which now is 0-12v) is fed to the micro-controller through a 7805 regulator. That worked fine, but someone told me that method is not nice and not suited for reliable applications. I also feel that's ugly but i don't expect to mess around a lot with hardware, building separate circuitry etc... Can someone propose any better solution (or agree with mine :D).

I prefer a lot if i don't have to build any circuitry at all. If not possible, at least very simple one!(simple in the sense of hardware complexity. a circuit that don't need a PCB, just two wires here and there. That's why I love 7805 solution). However (unfortunately) the highest priority has to be given for reliability.


texts: What does a capacitor do in a tesla coil?

texts: I just can't seem to understand what a capacitor does in a tesla coil. Could somebody explain what the capacitor does? I'm new to this kind of thing, so could you write it in a moron friendly way?


texts: Can I decrease voltage in a battery to get higher amp hour rating?

texts:
I am willing to use my 7.4 volts 1000mAh lithium polymer battery to power a motor that works with 3.7 volts, so I will input the 7.4 volt to a high efficiency buck converter to get an output of 3.7 volt, which is connected to the motor, Assuming that the motor draws 1 Amp, my question is will I will still get 1 Amp for only 1 hour from the output of the converter or I will get 1 Amp for two hours ??

The total watt hour for my battery is as I know 7.4 watt hours (V*Ah) but my motor draws 1 Amp at 3.7v so watt hours of 3.7 watt, so If I divided the watt hour of my battery by the watts my motors draw I get 2 hours, Is these calculations correct or there is another rules or factors that affects it ?

I am a school student by the way so, please if you answer me, answer me in full details as if I don't know anything.

Thanks in advance.


texts: Driving servo with the help of microcontroller

texts:
I'm making a driver board for servo TowerPro MG946R based on ATtiny13. PWM parameters have been taken from manuals: signal period ~13 ms, pulse width ~540us - ~2400us (checked on oscilloscope), but servo doesn't breathe.

On this site there is a parameter Pulse cycle - 1 ms. I've read somewhere that this high frequency can kill servo. Should i try it?

Also is there some dependence of power supply voltage level for servo and voltage level of PWM signal? Mine are 6V for power and 4.8 for signal.


texts:
I need to discharge a lot a energy in a short time from a capacitor, I don't have the numbers yet, but my question is if the power of a capacitor is limited for some others parameters of this.

Theoretically the energy stored depends of the capacity of the capacitor and the time of discharge can be adjusted with a resistance in order to change it. With this parameters I can obtain the power that the capacitor will give.

I'm trying to "power" a tungsten filament, like a light bulb, in order to transfer the energy for a chemical reaction, also I want to transfer a few Joules in a few nanoseconds.

Should I consider another parameters for this problem?


texts: How to mount a DB-9 adapter to an enclosure

texts:
I have a DB-9 connector that needs to be mounted to an electronics enclosure. This hole for the DB-9 connector will be manually cut out.

Question: How can the DB-9 connector be secured to the enclosure?

I am using the following DB-9 connector. I need a DB9-to-DB9 connector, not DB9 connector on one side, and some other pins on the other side. Is there a better variant of it that has mounting screws or something?


texts: Latch circuit with transistors which is initially on?

texts:
I just learned about latch circuits and built the one displayed here in Fig 75. Latch Circuit (B):

The LED is initially off. How can this be modified to be initially on?


texts: How to measure capacitive coupling on pcb traces?

texts:
I have bare PCB board (6 layers) with me and I would like to see if my switching signals (60 kHz) have any effect on the sensitive current measurement lines.

I just want to know if there is quick test by sending a pulse on one trace and checking the other trace on oscilloscope.I would like to know the test setup?
How should these traces be terminated and by how much resistance?


texts:
Hello fellow human beings,

I am really bad at transposing equasions.
In the picture you can see a simple circuit, of whom I need the equasion in the form: 'Z = Re + jIm'.
I know how to get to the equasion, as you can see in the image, but I have no idea how to get it into the form of 'Z = R + j( w;C;L )'.

Thank you for letting me know, how you would start solving.


texts:
In the EVM datasheet schematic, two input beads and 2 output beads are used.

In my application, I drive 56V 5A COB LED. Input voltage is 22-50V, so input current can be ~6-13A. I read on Internet, that beads saturate and lose their filtering efficiency, so, it is better to use beads with current ratings 3-4 times higher. How can I implement such filter, as in the example in the datasheet? There are no ferrite beads with current ratings higher than 11A.


texts:
I'm about to replace a relay with a discrete triac design. The load is a (resistive) heater element and power 1200W @ 240V (RMS current ~5A). I will use zero crossing detection and max switching frequency of 1Hz. Environment temperature < 50C. The triac is fired from an mcu via optocoupler.

I'm looking for advices to create a robust solution from a practical point of view and in particular from field experience.

What rating should the triac have for V and A.
Is it possible/advisable to avoid a heat sink?
Voltage surges are common in the region, how will that effect component selection?
Can a (fast) fuse be effective in protecting the triac from short circuit and power surge? If not, are there known working solutions for circuit protection.

Thanks in advance!


texts: What makes a magnetic field probe insensitive to E-fields?

texts:
Consider a magnetic field (B-field) probe such as this one:

(source)

I understand that as as the magnetic flux through the loop formed by the coax shield changes, the charge carriers in the loop will be shoved around the loop by Faraday's law of induction. Since the loop is small relative to the wavelength of interest, we can pretend that the current in it is constant. The high impedance formed by the gap at the top means this induced current will be accompanied by a voltage difference at the gap, and that voltage difference will travel down the transmission line formed by half of the hoop and the feedline to \$Z_L\$, where it's measured. In this way, the probe measures the B-field.

But, what about the E-fields? The point of this probe is to be maximally sensitive to B-fields and minimally sensitive to E-fields. Why is it not sensitive to E-fields?


texts: Why are components hard to insert into a breadboard?

texts:
I have just bought a breadboard, but I have notinced that the components are hard to insert into the holes (and sometimes only one pin go in and the another one go out, like a LED).
In videos I see people insert componenets into breadboard very easily.

Is it normal because it is a new breadboard?
Will it be fixed soon ?
Any way to make inserting compomemts easier?
I tried to use a jumber wire to help making holes bigger, but it didn't helped.


texts: How to create documentation layer at PBC at home

texts:
I am making my own PCBs at home with printing on laser printer. Creating copper layer and non-soldering pads is easy, but I would like add documentation layer too and now I am stuck. How do you solve this problem?

I can do PCBs like this
, but I would like to add the while texts on them too like here

Is there an easy way to doo that? Thanks for all suggestions :)

EDIT

I fount this
https://www.aliexpress.com/item/Super-PCB-UV-photosensitive-inks-white-PCB-UV-curable-solder-resist-ink-solder-mask-UV-ink/32684337516.html
and first test came out good:

First of all - I am really happy and satisfied.

The ink came good packed, wrapped in a lot of plastic bubles and the container itself was packed in extra layer if thin plastic. Anyway a part of the ink was split over the can, not much, as the inner plastic keep it tight as you can see. The can screw is not very tight and in consideration, how long it traveled (free delivery), the result is not bad at all.

The can is half full, see
and
 - I show, how much full  was. It
will last me for years, I think.

I used part of those splits (not nearly all) for fast test - treated it as
other UV curable solder resist - I run it thru cold laminator in plastic bag,
placed laser-printed clear scheat over it, weighted it with glas and exposed
for 20 minutes (maybe 10 would be better as some small point was hollowed, but did not cler fully after), then gently rub it with spirit (alcohol, C2H5OH).

You see result on the last foto - even small pads for SMD parts (atmega328)
went well. There is a big hole in lower part, where the ink stuck with the bag instead of PCB - I blame myself to not clean the PBC at all and it will went better next time, as I get better with this ink and adjust my process for it.

The result was basically really really good. But the smalest letters was not
fully readable as its insides went all away, while some other little holes
(the spotted line on top) end hollowed, but not fully cleaned thru. As I want
it for Silk Screen mainly (those names printed all over PCB) it is not
problem, I just would use 2. smallest fot and use it in bold variant.
I tried some markers to write over, but none stick well. So dirt would
probably also not stick. The painting is not as hard as green UV solder mask,
can be mechanically scratched off easily (as in winning ticket - cratch this
area and if you find 3 stars, you won). So for soldering it is OK, but not for long time protection/duration under mechanical influence. I will engrave core info to the copper anyway, this I would use for more visual hints.

Maybe more UV after-curing would little hardened it too.

The color is nice glassy white after curing.

As you can see, it is negative (what is exposed to light will remain, what is hidden goes away )

Edit: 2017-06-16: I tried to make full documentation and hit some problems:

as the white covers the PCB, nothing under it can be seen, so it is extremly hard to right align the printed mask (I should made some marks away from covered area just for this reason)
it does not stick well to the green non-soldering paste - cleaning unexposed white many times take small parts of exposed white away too (even if it was hardened and separated well from cover, leaving empty space on it)
also if there is any miss-alignment and the white cover some sordering pad, even if I cut the white before removing, usually also some other parts went off. Finally from like 30 marks was left only like 10 and half of it was moved from original point.

So the white ink performed even worse on the non-soldering paste then on uncleaned PCB. I will try combining layers of grean/red/yellow/blue pastes next time as the masks can be preciselly aligned and smaller details can be used to form symbols. I will report then here too.

I will use the white ink only on small parts of PCB next time - like logo, version or date aligned with decorative copper parts of PCB only.


texts: I want to put a low pass filter infront of my ADC. The ADC's sampling rate is 10MHz. I want to sample a signal with a maximum frequency of 50 kHz. So my cutoff frequency for this low pass should be slightly higher than 50 kHz, right?


texts: I'm getting 512 as a reading from a thermistor. Trying to convert this into something readable but having a hard time

texts:
I just recently purchased a KY028 Temperature Sensor located HERE. I was having trouble hooking this sensor up so I snipped off the thermistor and shoved it in a breadboard. I know it sounds tacky but here is the picture of my circuit I have going now.

I have the +5V pin on my arduino connected to the thermistor then the 10K resistor connected to the negative side of the thermistor then going to ground.

I have researched several sites on how to convert the reading i'm getting into kelvins and/or C and/or F but i'm not getting a correct value as a final result.

This website HERE. It's providing me with an equation to solve for the thermistors resistance which is as follows....

It then tells me to plug this value into Steinhart HART equation as follows....

The problem is i'm getting a negative value for the first equation. My Vout is at 4.983 Volts. When I plugged this into the first equation to find the thermistor resistance I get a negative value which is -5.950435k ohms.

I can't plugged this value into Steinharts equation because i can't take the natural log of a negative number. So this is the first problem i'm having. Plus A, B and C are constants which i'm unsure if I should use the standard values they have on that link I attached or find them for my specific thermistor. However, i don't know how to do that so i'm using the values they provide.

Next problem is I don't see where I'm suppose to use the reading i'm getting from the analog input pin i have connected to my thermistor which happens to read a value of 512. I'm not using this value anywhere in these above equations so as a result i'm completely lost at what to do.

I have found several sites containing programs already made like this one HERE. HOWEVER, i'm not interested in copying their code as I would have no idea what's happening. I tried to understand their code for the conversion part but it's not the same as the equations i provided above. The person even says he used that same link to do the conversions but he must of manipulated the equations to do the conversion because i'm not following his code. What I would like is an explanation of how I can go about converting this value without using huge lookup tables as a cheat or copying code. I'm wanting to replicate my own result but i just can't understand what I need to do. Can someone put me back on track here.


texts: Reverse voltage flowing from drain to source in P channel MOSFET

texts:
The below given circuit works as a switch. The P channel MOSFET has max Vdss = -30V and Vgss = +/- 20V.MOSFET DATASHEET

The voltage divider protects the gate of the MOSFET from exceeding it's Vgss in case if high voltage is applied.

Now the issue is, when external +12V is applied to Output 2 connector as shown in image, the voltage flows from  Drain to Source and flows through all the regulator and generate +5V. [Ground is always there]

Whereas +5V should only be generated when 12V is applied to the 12V connector.

The simplest solution is to use a diode at the output 2 which will stop any reverse voltage and only allow forward voltage through it (while switching).

But why the voltage is flowing from drain to source when circuit has no power, why does Led glow (means 5V generated).

What else can be done to rectify this issue apart from using Diode?


texts: Drive relays with optocoupler and a Raspberry pi

texts:
I'm currently designing a PCB in order to drive relays (5V) with an optocoupler and a Raspberry pi (a CNY74-4 here is the datasheet). So I made this schematic:

My questions are the followings:

Is my scheme right?
The 5V come from an DC/DC supply which deliver 2.1A and 5V, it's not a problem for the optocoupler and the transistor?
Which CMS transistor can I use in this case?
Is the optocoupler good for this use?

THanks for your answer!


texts: Feeding back into a rail of a power source

texts:
I have a power supply with +12v, +5v, and GND rails.

Is it good practice to put a 7v motor across the 5 and 12v rails?


texts: For a J-K Flip Flop, once we have J&K=1, now when the CLK Goes high, so Output goes high on the falling edge, but when does the OUTPUT Goes back to LOW?


texts: Is it safe to connect a small solar panel to a lead acid with only a diode?

texts: Is my setup safe? I'm connecting two 7.2v 100ma solar panels in parallel using two 1N5817 then to a to 6v lead acid battery with a Constant Voltage Charge of 7.3-7.4v for cycle use.I can't use a MPPT or PWM solar charge controller do partly do to lack of space and partly because it with be in a water tight box with no ventilation.