texts: Analog joystick control, MCU or other option?

texts: I need to add some navigation control to a project I'm working on.  I'm looking at the CTS 254 which is just a two pot analog joystick.  I assume I can just get it's Xy coordinates by using a micro-controller with two adc inputs but I was wondering if there was an easier, perhaps code free way.  I really just want to get the xy coordinates up to my main processor over I2C.  Just wondering if there was another option here I might not have considered.


texts: When base is open, is the base-emitter junction reverse biased? How does leakage current from collector to emitter flow?

texts:
I've been studying photo transistors, but I'm rusty on leakage current in bjt.
I don't get why CE leakage current is \$ 1+\beta \$ times CB leakage current.
It seems like the bjt amplifies CB leakage current. I have two questions troubling me:

How can a thermally generated electron-hole pair in CB junction contribute to a current from the supply? Won't the BE junction stop it?(Because the charge carriers have to cross two reverse biased junctions)
The leakage current relation \$I_{CEO} = (1+\beta)I_{CBO}\$ seems to suggest that the common emitter configuration amplifies the leakage current from collector to base(\$CB\$). How can leakage current from collector to base be amplified to produce a huge leakage current from collector to emitter?

simulate this circuit – Schematic created using CircuitLab


texts: How would one design a circuit to detect energy in the 3-140GHz ranges economically

texts:
We are looking to make something to detect RF frequencies in the SHF and EHF bands, from 3-140GHz, without requiring much frequency or amplitude accuracy.  It would be ideally split into a few bands, e.g. 3-30GHz, 30-60GHz, 60-100GHz, and 100-140GHz.  So essentially any energy in each of those bands above some threshold would just trigger a logical output.  Being able to quantify the intensity of the energy would be a bonus (and again it doesn't need spectrum analyzer precision), but not essential.

So it seems to me that I won't be able to design any simple active bandpass filters in those frequency ranges, although I suppose I can develop passive bandpass filters with the right components.  But I haven't found components yet that appear to support those bands.  I'm also not sure how to deal with antenna requirements.

Any comments or suggestions are welcome.  Thanks.


texts:
I'm looking to use the LM324n (http://www.ti.com/lit/ds/symlink/lm124-n.pdf) single-supply op-amp in non-inverting mode:

The goal is to take a voltage of around 100uV and multiply it to around 1V (i.e. let R1 = 100 ohms, and let R2 = 1 megohm), while supplying the op amp with +5V on one end and GND on the other end.

Will this work?


texts:
We have \$z(t)=\cos(100πt)\cos^2(500πt)\$ .

Find Nyquist sampling rate.

Well, I know that \$f_s=2f_{max}\$. My main problem is that I am not entirely sure if I could re-write the above signal as: \$z(t)=(2π50t)\cos^2(2π250t)\$, and say that \$f_{max}=250\$, therefore \$f_s=500\$Hz. That \$\cos^2(\cdot)\$ troubles me a bit. Anyone could help? Thanks.


texts: How to control a motor with only relays and push button?

texts:
Hello I´ve been working in this project for some days, I need to make a circuit with only relays that can make a dc motor start, stop and a reverse. The thing is that when you push the start or the reverse button the motor need to keep running, I can´t keep it pushed.

This is as far as I can get. SW1 turns the engine on, SW5 turns it off and SW7 reverse the motor but only if it is already running. What i need is that the reverse button also turns the engine on.
Please help.

notes: -i can only use three push buttons and as many relays as needed. Yes is a school assignment.

THANKS!


texts:
Any suggestions on a low-power programmable timer that does something like the following (to wake up a microcontroller)?:

Shortest delay I need is about 10ms.
Highest delay I would like is a few hundred ms, but I could get by with less.
Precision I would like is 100 PPM (10us).
Operates on 3V battery, and is mostly immune to voltage variations of 20% or so.
It would also be nice if current was well less than 100uA.

...or am I asking for way too much? Any comments or suggestions are appreciated.


texts: ADC input filter design for DC input signal

texts:
My plan is to use an ADS1115 ADC to read a low impedance 0-5V output signal from a level transducer. The ADC data sheet gives guidance for ADC input filtering. This data sheet, and even other input filter design notes all assume a relatively high frequency input signal (High frequency relative to my application).
My application is a level transducer that will mostly be 0v for the majority of its life. I will only be monitoring the input signal for a high level event. If a high water level were to occur, it would happen very slowly, it would take over 10 minutes just for the level to increase an inch. Once the level reaches a high threshold; however, level reading accuracy is critical.
My design is power critical, runs on battery. I chose my sampling rate to be 64 samples per second. The entire system will wake from sleep, take a few samples, average them, and go back to sleep (sleep duration will be a few seconds). The transducer is mounted directly onto PCB via one or two inches of wire. Industrial environment, very noisy environment as wel.
Given this application, is a RC circuit really necessary? I would imagine just removing the resistor from the RC circuit and letting just capacitor filter all AC noise would be enough for my application? I would of course still use the differential capacitor as per the data sheet. Or would it be better to make a RC filter with a very low cut off? That was my original plan, but the use of precision resistors and required class 1 caps would eat into board space and allotted budget; I didn't want to go this route unless it would be necessary.
Thank you for taking the time to read!


texts: How to interface 1 MSPS ADC with processing module in FPGA?

texts:
I have DE1-SoC board which contains 1 MSPS ADC, I am trying to take samples from ADC and process them. ADC Controller clock is 20 MHz and data is available every 16 clock cycles. The module that takes samples operates on 100 MHz clock. The problem is how can I interface these two modules?

My first thought was to use an asynchronous FIFO, but after search I figured out that it is impossible! Writing clock is much slower than reading side. I found a formula to calculate the depth of the FIFO (here) but it failed, giving me a negative answer! I didn't know what my "burst" is, so I assumed it to be 1 as the controller gives one sample every 16 clock cycles.

So, do you have any clue of solving this problem?


texts:
How much horizontal overscan is there on a typical NTSC CRT television set?

Vertical overscan, there are nominally 240 scan lines per field, of which you can reasonably count on having slightly more than 200. 200/240 = 0.83, so you can use 83% of the nominal screen height.

Horizontal overscan, there are nominally 228 color clocks per scan line. If the same ratio were to apply, 228*0.83 = 189, so you could count on having about 190 color clocks per scan line.

However, https://en.wikipedia.org/wiki/Atari_8-bit_family#Playfield_graphics_capabilities says one family of computers that was highly regarded for its graphics capabilities in the age of NTSC, considered 192 to be into overscan, and 160 color clocks per scan line to be the normal safe value.

Which figure is correct?


texts: I am try to build a wireless sensor(right now I am using an adxl335 accelerometer with an analog output) but this project should be general for any sensor that outputs analog. The issue is that I have to first convert the analog to digital to transmit it over RF(I have a 12d,12e RF series which is a four channel Rf transmitter with reciever). But the issue is if I need to convert the analog to digital then I need a microcontroller for the CS as well as clock lines. This just adds enormously to the cost of the project as well as the number of hours I would spend assembling them together and a microcontroller for each sensor does not seem sensible at all. I am wondering what is the general route taken to make an accelerometer or any other sensor that outputs anolog wireless.


texts: Beam sensor or other switch needed for electric blind project

texts:
I am designing a motorised blind (powered by a Raspberry Pi) and need a reliable way of detecting when the blind is fully "up" or "down".

I don't want to use a stepper motor, and rely on counts, as I want it to handle situations where the Pi crashes / power cycles.

The simplest way seems to be a switch or sensor to detect when the blind is up or down, and I think a beam sensor would be neatest. The sensor needs to work in the dark, as the blind should be able to function at night. (I plan to automate it so the blind closes when there is no-one in the room at night.)

Have looked on Adafruit, but can't see anything suitable. Does such a thing exist?


texts: Design a T flip flop and draw the asynchronous state diagram

texts:
I am supposed to design a T flip flop using logic gates (asynchronous sequential circuit) and also draw the state diagram. I don't really understand why the output doesn't change from 0 to 1 when there is a transition from B to D in the given figure below, because for the T flip flop the state 11 causes toggle action, doesn't it? Can someone help me figure this out.

Truth table for T flip flop:


texts: Can I use both a wifi shield and an LCD shield on my Arduino Uno?

texts: I got an Arduino Uno for Christmas and just ordered this wifi shield, but I'd like to use it with an LCD shield. Can I just stack the LCD shield onto the wifi shield? Do I need any extra hardware to connect them?


texts:
What is the formula for Vdc of a Center tapped full wave rectifier?

Is it

0.636*Vac - Vk (where Vk is the potential drop across a single diode. Assume both diodes have the same cutoff voltage)

or is it

0.636*Vac - 2Vk

It's not given anywhere in my textbook and I couldn't find it on the internet either. Logically the first one makes more sense to me because for every half-cycle, input voltage is across just one diode unlike in a full wave bridge rectifier where the input voltage is across two diodes.


texts: Do UART pins on the Beagle Bone Black require tri-state buffers?

texts:
The project I am working on uses a Beagle Bone Black (BBB) rev C, we are powering it externally through a cape according to the System Reference Manual's instructions.
The System Reference Manual makes it clear to not supply voltages to any pins before the SYS_RESET pin goes high (see here). The usual solution to this is to have any external circuitry be powered by the BBB's 5v or 3v pins. However, we cannot use this solution because we have a Teensy 3.2 that is running independent of the BBB and is connected to the BBB's UART2 pins (P9 header, pins 21 and 22). So we will be using a tri-state buffer to prevent voltage being applied to the pins when SYS_RESET is low, as discussed in this question.
I am worried that a tri-state buffer will interfere with the UART communication between the Teensy 3.2 and the Beagle Bone Black, or if a tri-state buffer is even needed on those UART2 pins.
TL;DR:
Is it possible to use a tri-state buffer in the middle of a UART line?


texts:
I would like a slow PWM output, driving a relay turning an AC heating element on and off.
I desire a period time of around 10s.

What is a realistic upper period time limit for a PWM circuit like the one found here?

According to EveryCircuit, a 100 kOhm potentiometer and 100 uF C1 capacitor should leave me with my desired ~10s period time, but I suspect noise could become an issue with resistances so large and period times so slow.


texts: would this be safe to control servo with usb

texts:
i've been asking around and people has been telling me that the max current a usb can supply is 100 ma then 200 ma then 500ma then the http://en.wikipedia.org/wiki/USB says 0.5–0.9 A (general) 5 A (charging devices)

i need control and supply a small servo with no load current of 100ma and stalling current of 900ma, how safe is that, do i need a fuse ?


texts: I am designing a SPDT RF switch that operate within UWB frequency range of 3.1 GHz to 10.6 GHz, the switching element i used is NXP PIN diode model BAP64_02, however I encounter a problem which the diode having bad insertion loss at 10 GHz and I doubting is it the self-resonant problem happen in the diode, if yes, do I have any solution to counter this problem?


texts: Behavior of Art of Electronics highpass filter depending on resistance value

texts:
While reading The Art of Electronics (3rd Ed.), I was stumped by a particular assertion in section 1.7.1C, "Blocking capacitor":

  For instance, every stereo audio amplifier has all its inputs capacitively coupled, because it doesn't know what dc level its input signals might be riding on. In such a coupling application you always pick R and C so that all frequencies of interest ... are passed without loss ... That determines the product RC ... You've got the product, but you still have to choose individual values for R and C. You do this by noticing that the input signal sees a load equal to R at signal frequencies ... so you choose R to be a reasonable load, i.e., not so small that it's hard to drive, and not so large that the circuit is prone to signal pickup from other circuits in the box.

What do the authors mean with a small resistance being "hard to drive"? Also, why does a high-value resistance affect signal pickup?

I can only guess, but my hypothesis is that signal pickup may pop up because the cutoff frequency is lowered when R is increased, and lower frequencies pass through. A low resistance may become hard to drive because of wasted power?

The schematic:

simulate this circuit – Schematic created using CircuitLab


texts:
I have been trying to create an atmel project that uses FreeRTOS on an ATmega328 but I cannot seem to get it to work. I have read several article on how to do this, especially this  and this one (which is in french but google translate should do the trick). Basically, what I did was to:

Download the FreeRTOS source code
Create a new Atmel Studio (C executable) targeting the atmega328
Add the FreeRTOS source code to the project (respecting the folder structure as suggested in the tutorials)
Then compile it. However, I get this error "FreeRTOS.h: No such file or directory"
I have made sure to add all the source file in my compiler's directories (again as suggested by the tutorials) but I always get the same nasty error. Heck, I have even downloaded the attached templates (from the tutorial sites) but I get the same compile error. Does anyone knows how to solve this?
PS-
I am using Atmel studio 6.2 sp2 on windows 8. My compile is the default avr gcc.
My directory list looks like this
My defined symbols looks like as follows
The completed Atmel Studio 6.2 solution is shared to google drive if someone would like to take a look at it
Google drive link of the complete solution


texts: Can I directly read an analog sensor data from the Xbee's ADC?

texts:
I've posted this on the main StackOverflow and was suggested to post this here:

By rule of thumb, I've searched at least 10 different sources for my question before coming here.

My question is: if I have a Raspberry Pi that is connected via UART communication to an Xbee with a connected analog sensor (say IR distance sensor), can I read the sensor data directly from the Xbee on the UART communication?

The only sources I can find only address an Xbee collecting the sensor data and then sending it over the RF signal to another Xbee. None of the sources seem to explicitly address the Xbee acting as an ADC for my Raspberry Pi target.


texts: Is it bad practice to place a LiPoly battery underneath a PCB in an electronic device?

texts: I'm designing an electronic device and have considered placing the plcb on top of the battery within the device to minimize space used. My gut tells me this is unwise however. What concerns are there for placing a pcb on top of/underneath a lipoly battery?


texts:
i just wanted to verify if my insights are correct regarding the title/issue of this question. I don't have any hardware for me to see the output so i'm trying to visualize it via math and though simulation.

i read a lot of daisy chain blogs, sites but i seldom see detailed information about receiving data from these daisy chains (more on master output/broadcast data to daisy chain slaves) or over receiving data from one (1) SPI slave also haha

Here's the site i lastly read but still gave me a vogue idea about it. (maybe i'm too dumb to realize it w/o details xD)

https://learn.sparkfun.com/tutorials/serial-peripheral-interface-spi

1) First question, i understand the image above which means that as long i sent a byte (8 bit; command/instruction) from uC to an SPI Slave via MOSI line, this SPI Slave will automatically send a byte data to the MISO line w/o disabling chip select. When the byte data sent by SPI Slave was received by uC is the time i should disable my chip select. Is that correct?

I ask about it since when it comes to daisy chain, it looks like this is not the case. After i read through the sparkfun's spi tutorial as well as on maxim's blog note on SPI https://www.maximintegrated.com/en/app-notes/index.mvp/id/3947

instead when daisy chained, even though the 1st SPI slave receives a byte of command, it will not execute it and continue to pass the byte command to another SPI Slave when it receives another byte, NOT UNTIL I DISABLE CHIP SELECT will execute the received command(s) on SPI Slave(s). Is that correct?

2) Second question, do SPI Slaves in daisy chain automatically understood or separate bits into instruction like let's say SPI Slave1 receives 2 byte of command. After receiving the 1st byte of command and receives a bit from the 2nd byte of command along the way, does this slave will flush one time the 1st byte of command to the SPI Slave2 for it to have only a 1 bit from the 2nd byte and would accept the following bits for it to complete the 2nd byte command? would it be among the two on the table below?

3) Third question, if on daisy chain setup and the statement/process of disabling the disabling the chip select would execute commands being held by Slaves is true, how would the feedback of data transmission on MISO line to uC would look like then? I have this SPI device where after receiving a 1 byte command, it will feedback 3 byte data. Would it be among the two on the table below?

I hope you could ease my this conflict like a tumor in my head :D thanks.


texts: How to calculate dynamic power consumption of an decoder without using an simullator?

texts:
I am currently working with a circuit which uses a n-to-2^n line decoder. My question is, how to calculate its total dynamic power consumption for a given input?
To calculate the exact answer, my guess is to calculate power consumption of each possible input and then take its average. However, I am unable to move on from the first step.

It will be great if someone give any pointer on this.


texts: Negative Feedback Op-Amp as input to ADC

texts:
I have a target board(With Nuc240,Cortex M0) with ADC connected through an OP-Amp(NE5532APSR) as shown in the image.

where AINV1 is the input(0-30 V) and AINVI_ADC is the input to Microcontroller(0-3V) and AINV1_GND - Analog input voltage supply ground

I configured the inputs and I'm getting the Digital values in the range 0 to 4096.
for the 12 bit ADC. The input to Op-Amp(negative feedback) ranges between 0 to 30 volt for which corresponding microcontroller input will be 0 - 3 volt.In the code,should I consider the input resistance R44 and R48 in calculation or just multiply the ADC reading by 7.324*10^-3  ie. -> (3/4096 * 10) to get the exact input voltage, if not what are the parameters I must consider?


texts: How to plot thermal noise in the time domain?

texts:
The power of this thermal noise is given by:
P = 4kT (k = Boltzmann’s constant, T = temperature (Kelvins))
And, thus, the voltage by:
V^2 / R = 4kT (R = resistance)
Finally, we must take into account that this voltage follows a Gaussian distribution, with an RMS given by:
√4RkTB (B = bandwidth)


texts:
Let us consider a linear time-invariant system. The term minimum phase is used for a system that has stable poles and stable zeros. A system is called nonminimal phase if it is not minimum phase.

The problem that I have is that these definitions do not make it clear if a system with one pole or one zero which has a real part of zero is still called minimal phase or not.

Is there some reference that is giving a clear definition of the term minimal phase?


texts: I've a problem where I should expect how a circuit will behave with a charred resistor. So should I consider this resistor a connecting wire or an open switch?


texts: Flyback Regulator and Flyback Transformer

texts:
I wish to generate electric sparks for some fun. I found out that Flyback Transformer are well suited for my purpose.

But I do have a simple 220/25V Transformer. I do not want to do winding for converting it to a flyback(also I do not know how to do it). I saw a circuit Online called Flyback Regulator:

Can I use this circuit instead to do my work? Can I just plug in an oscillating circuit at place of a PM generator and produce sparks?


texts: What are the resonant frequencies for this RLC circuit?

texts:
What are the resonant frequencies in the following circuit?

Full disclosure: this is question 34 on page 655 of Pearson's Electronics Fundamentals 8th Ed.

I recognise the parallel section comprising \$C, R_{W_1}\$ and \$L_2\$ and compute a resonance at 2599Hz using \$f_r = \frac{1}{2\pi\sqrt{LC}}\$, and find \$V_{out} = 9.8\$V (given \$V_1 = 10V\$) at this frequency because the parallel section is equivalent to a single \$41671\Omega\$ resistor.

However, the question implies that there is more than one resonant frequency... what are the others and how are they deduced?

simulate this circuit – Schematic created using CircuitLab


texts:
Hi I want to implement a narrowband FM transmitter and I find all features about power and noise in the FM Modulator datasheet, but nothing about bandwidth.

The transmitter will work at center RF frecuency of 408.01250 Mhz being the channel bandwidth 25 kHz (408-408.025 Mhz).So the modulated signal would have a 25 kHz bandwidth.

I'm been searching for weeks the FM modulator in many manufacturer websites and finally I found this one  with integrated PLL.

But the thing is that I can't find the bandwidth, I find some Frecuency Deviation tables and Modulation depth but nothing to work around with Carlson Rule or something similar.

Do you know where are located the related bandwidth specs on modulator datasheets like this one ? Maybe it can't be used for FM narrowband because it seems to have a Deviation Frecuency around -/+15 kHz.


texts: How to individually control electromagnets in a 16x16 matrix?

texts:
I'm looking to be able to individually control each electromagnet in a 16x16 matrix. It's also important to note that I want to control these via an Arduino and maybe eventually a Raspberry pi - depending on the future requirements and environment I want to work in with my project. Both however, limit me pin wise.

To get around my lack of infinite pins, I was looking into multiplexing, but I'm not sure how I'd go about it completely for 16 columns and 16 rows. However, I'm also honestly not 100% sure that multiplexing with electromagnets is an ideal solution because I'm not sure how much that will effect how strong the magnet works, due to it turning off and on repeatedly. I'd assume I might only get ~6.25% potential output from the electromagnets due to multiplexing, but that's assuming electromagnets work well in a multiplexing environment - for all I know they need some "warm up" time - but again, I'm not a real electrical engineer lol. I imagine since electricity is flowing through the electromagnet I should expect the electromagnet to turn on/off almost as instantly as an LED.

The electromagnets I have on hand are ZYE1-P20/15's. 12V DC, 3W, 0.25A.

So, if you think multiplexing might work, could I get any good recommendations on what driver I could use to multiplex for a 16x16 matrix? Any tips and advice would also be welcome.

If you don't think multiplexing is a good idea, what other options are there?


texts: Looking for a formula for calculating maximum induced AC voltage in two air coils next to each other

texts:
I've got a question about electromagnetic induction. I've already done some research but I'm unable to find the easy solution.

I want to calculate somehow maximum voltage peak that will be induced in secondary coil in AC circuit. For sure I have all input data here.

Circuit is obvious. There's primary air coil L1 connected trough a resistor R to sinewave AC voltage source U1 (oscillating with frequency f). Through the L1 coil flows AC current I.

I know every value here including L1 inductance, diameter, turns qty, winding wire radius and even non-ideal solenoid params like resistance and capacitance.

Next to the coil L1 there's secondary air coil L2, also with all known parameteres, and L2 is located next to L1 the distance l (in a straight line). L2 is contected to analog voltage meter to measure U2 voltage peaks.

Electric circuit:

Coils phisical relation:

Question: How to calculate maximum voltage peak U2 that will be induced in the L2 coil? Does a simple, school formula U2max = ... even exists? Even poor approximation would be good enough.


texts: Hii can anyone explain how to do this. Its Given Answer as 6A. What exactly happens when a constant current source in series with inductor? TIA


texts: How do these phototransistors circuits work?

texts:
In the figure 1, When there is insufficient light, the darlington transistor is biased on, keeping the relay energized. When there is sufficient light, phototransistor FT turns on; I imagine this turning Q1 off and de-energizing the relay but I don't understand why.

In the figure 2, Why is the collector and emitter shorted?.

Thanks.


texts:
I refer to the explanation I picked up from a pdf below. Please note a person who already has knowledge on A-GPS and CGEE and SGEE does not have to read the explanation provided for those below.

I know SGEE is downloading the Ephemeris information from the GPS Vendors server. Which I think is also scary in some aspects. (if anyone had any comments with regard to that kindly discuss)

My second Question is if a GPS is saving the used Ephemeris data in RAM and using the same in next startup. Is that called A-GPS or CGEE (Client generated EE)?

Explanation of Technologies

What is Assisted GPS?
Assisted GPS or A-GPS uses some other communication channel such as WiFi or the mobile phone network to assist the GPS receiver by delivering current time and ephemeris data for all the satellites in the system. Having the current ephemeris data allows the receiver to be more precise in it’s searching, which makes the receiver sensitivity effectively the same as the tracking sensitivity. That is, it makes any start, a hot start. With A-GPS, the network provides the Ephemeris data to the GPS receiver to improve sensitivity the TTFF. Assisted GPS or A-GPS is also used to improve the performance within buildings where the GPS signals are by 20 dB or possibly more. Again by providing information to the GPS receiver in the
mobile it is able to better correlate the signal being received from the satellite when the signal is low
in strength. Using this technique it is possible to gain considerable increases in sensitivity under
regular use-cases.

Client Generated Extended Ephemeris

Client Generated Extended Ephemeris (CGEE) is calculated on the client using broadcast ephemeris data downloaded for visible satellites. CGEE provides three day Extended Ephemeris (EE) models for visible satellites and stores the data in local memory. With CGEE no network connection is required.

Server Generated Extended Ephemeris

With Server Generated Extended Ephemeris (SGEE), a server obtains information from world-wide tracking stations and calculates the EE data for all GPS satellites at least once a day. To receive the data a network connection is required to download the data. Typical size for a one day payload to cover the entire constellation of satellites is around 11 Kbytes. These files are typically provided by the GPS supplier and are available to download at no charge.


texts: How to correctly use the formula for calculating the air-gap in a pulse transformer?

texts:
To achieve a certain value of the magnetizing inductance (Lm), we can adjust the transformer air gap.

Air gap calculation formula:

There is no particular information on this, but I assumed that:
u0 = Vacuum permeability (4π×10−7 H/m)
N - primary turns? (x18)
Ae effective area (PQ5050) = 328mm2 (Core datasheet)
Lm = magnetic inductance (my goal - 60uH)

Substituting these values into the formula, I got 2.2 meters of the gap, which is clearly incorrect.
(0.000001257 * 324(18^2) * 0.328) / 0.00006

Next, I tried replacing N with the transformation ratio (n = 1.5), I got 15.46mm of the gap. This is closer to true, but still a very large gap.
(0.000001257 * 2.25(1.5^2) * 0.328) / 0.00006

I also tried to remove the square from N, but this is still a very large gap.
Question: what is my mistake? I assumed that the matter is in N (it is not clear whether this is the number of turns of the primary winding, or this is the transformation ratio (but it is denoted by a small n))
Perhaps there are other formulas with which you can get the Air gap value, the desired value of the magnetizing inductance?


texts: To what state(on/off) does the Vds figure in a MOSFET gate charge curve relate and how does the Id affect it?

texts:
For example, this is the gate charge curve of a p-MOSFET:

Let's say this p-Mosfet works as a simple high-side switch for a load. This load will have significantly more resistance than the mosfet in it's ON-State, so the voltage across the MOSFET will be very small.

I assume the ID is the current that will flow in ON state and that VDS is the voltage in OFF state here, is that correct?

Also, how would this curve change if the Id was very low, 1mA? (For example, we're switching a 24V supply for a 24k Ohm load, the voltage drop across this particular p-mosfet would be in the vicinity of 5mV in that case.

In other words, I need to know how the total gate charge to switch the MOSFET will change if I'm switching a load with much more resistance than the R_DS_ON.


texts: How to find unknowns when there are current dependent sources?

texts:
simulate this circuit – Schematic created using CircuitLab
There is this circuit, I tried solving it using the equations Va/4 + (Va-10)/5 -2iy -1 = 0, Vb/2 + Va/10 + 1 + 2iy = 0, Vb-Vc = 5ix, (Va-10)/5 = ix, and Vc/10 = iy. Now, I dont know if my equations are correct since there are current dependent sources which im confused about. Are my equations correct? Any help is appreciated.


texts:
I would like to know what will happen in the circuit diagram below when the switch is on( connected to a voltage source and R1) and switch off(connected to the R2)

My thoughts...
For switch on only the R1 and VT will be left?
for switch off VT and R1 will be removed?
the capacitor will act as a source, am I right?

simulate this circuit – Schematic created using CircuitLab


texts: ws2812b 5050 60 led per meter 300 led strip power issues

texts:
I'm having issues trying to power my 5 meter 300 led 60 led per meter strip and I'm using the sp105e magic controller to control them.

I cannot get them to light up correctly. I have a 4.5V 100mA power supply and the LEDs flash very dim for 1 second then nothing.

I tested with a 12V 833mA power supply and I at least got to see them on, but could only use them at less than half brightness. The power supply was also very warm.

The LEDs themselves seemed warm to the touch but I assume that is normal. If these power supplies aren't right, how do I figure out which one I should use? What power/voltage/current do I need to produce full brightness?

I will not run them at full brightness but want them to be capable. I don't want to destroy my LEDs or burn my house down.  Any help from you guys would be greatly appreciated!


texts:
I've one system with rs485 with max485 chip with microcontroller (pin 2& 3 r connected to gpio).To access that system I've made one other system with ilx485 chip. Pins 2 & 3 of these are connected to gnd and 5v.when I'm connecting both system, I'm not able to receive the response from ilx485 one,but I'm getting echo of tx data.
To debug this I've connected A and B to scope, transmit signal levels are close to 5v but for receive data signal levels drops to 3-3.5 v. I guess that's why it is not able to decode the receive signal to proper data. I've tried to use different cable, biasing resistors and terminating resistor.
What seems to be the problem? Any suggestions?

Thanks in advance

EDIT -

Below is scope trace and RS485 board designed by me.

In the scope trace first train of pulse may be for TX data and second - RX data. As u can see voltage drops for RX signal.


texts: A question about heating of a slowly turning off MOSFET

texts:
I have an N-Channel MOSFET IRF530 with its datasheet used in the following circuit:

When turned on it passes 2.5A current.
So I first wanted to make some calculations to check whether I would need a heat-sink if it was continuously at saturated/on state.

Following the knowledge from this document:
For any power dissipation P (in watts), one can calculate the effective temperature differential (ΔT) in °C as:

ΔT = P × θ

where θ is the total applicable thermal resistance

The series thermal resistances at above model shows the total thermal resistance path a device may see. Therefore the total θ for calculation purposes is the sum, i.e.,

\$\theta_{JA} = \theta_{JC} + \theta_{CA}\$. Given the ambient temperature \$T_A\$, P, and θ, then \$T_J\$ can be calculated.

So in my case TJmax = 175°C,  Junction-to-Ambient θ given as θJA = 62°C/W

\$R_{DS}{(on)}\$ = 0.16 ohm

Since current is 2.5A

\$P = I^2 R = (2.5)^2(0.16) = 1W \$, so ΔT the temperature rise becomes:

ΔT = P × θ = 1 × 62 = 62°C

Let's say the ambient temperature is 35°C, then the total temperature becomes

35 + 62 = 97°C which is smaller than 175°C

First conclusion was the MOSFET does not need a heatsink.

Until I simulated the circuit...

What I noticed is that, in my application the MOSFET turns on very quickly, passes almost a constant 2.5A through itself for few seconds, and turns-off slowly. And during turn-off there is a time interval where I × V product becomes quite high.

Here is the voltage and current plot in LTspice where it shows how the MOSFET turns-on at time zero, stays on and turns-off slowly:

And here is what LTspice shows for the power during this time interval:

My questions are

1-) What kind of logical reasoning should I follow at this point? Pmax = 30W here. If I use the procedure I wrote at the beginning the temperature rise becomes

ΔT = P × θ = 30 × 62 = 1861°C

But this is insane. If I switch the MOSFET on and off many times I can feel by finger it really gets hot. In my application a push-button switch turns on the MOSFET and an RC delay turns it off. It doesn't repeat continuously I mean. Do I need a heat-sink here?

2-) This is about the power during on time. In LTpice during the on time as you see the MOSFET's power is around 500mW but I calculate the power dissipation as:

\$P = I^2  R = (2.5)^2 ( 0.16) = 1W\$ using data sheet's \$R_{ds(on)}\$. In my case \$V_{gs}\$ is 15V not 10V. Can that be the reason for this difference?

edit:

For @jbord39, power at the load R1 shown together with the MOSFET's power below:


texts:
I'm going to design a protection system for a 12V boat GPS using TVS diodes. I choose the ISO7637 pulse model in severity III, against of ignition pulse and battery disconnection.
To calculate the energy for this particular application, which curve I have to use?

8/20μsec
10/1000μsec or
10/150msec

and to derate the power of the diode, at what pulse width I have to read? At 0.5ms or at 1ms?


texts: Understanding a 2 transistor oscillator?

texts:
I asked a question here about why I was getting a sawtooth wave from a two transistor oscillator. While that question is answered, I don't understand how the circuit produces oscillation in the first place.

Circuit Diagram:

This is the circuit I've built.

In order to help the reader identify the errors in my reasoning, the following is exactly what I think happens.

1) Random transistor turns on first (Call it T1). Because there is now a pathway to ground for C1, C1 begins to charge with its right plate being positive and its left plate being negative through R2.
2) C1's right plate reaches a threshold where T2 is turned on. Turning on T2 gives a pathway to ground to C2, causing C2 to charge through R3 with a positive voltage on its left plate and a negative voltage on its left.
3) The increase in negative voltage on C2's left causes T1 to turn off. T2 can't stay on because there's no pathway to ground for C1.
4) Everything stops.


texts: How can I capture VGA (640x480) frames with RGB565 format from OV7670+FIFO (AL422B)?

texts:
I made a platform with LPC1788 (Cortex M3) which had external 8MB NOR flash and external 32MB (16bit) SDRAM. I connected them a CF7670C-V3 (OV7670+AL422B (FIFO)) camera module and I capture QVGA,QQVGA frames in RGB565 format to FIFO and then I save images data to SDRAM perfectly. also I wrote a software on PC and save image data via USART and then show that. I have a big problem with VGA(640x480) resolution. At VGA resolution with RGB565 format, All the time I have picture ,like a on "OV7670 frames are 640x308 not 640x480" post. I search about a Algorithm that I capture a whole color VGA(640x480) frame data in the SDRAM. What can I do?
How can I control FIFO_WEN and FIFO_RRST signals to get image data and save in to the SDRAM?

CF7670C-V3 Schematic link


texts: Why do we need to measure the vibration of rotating machinery (e.g., acceleration, velocity, and angular velocity) in three axis?

texts:
Why do we need to measure the vibration of rotating machinery (e.g., acceleration, velocity, and angular velocity) on all three-axis? Why aren't single-axis vibration signals (e.g., only X or only Y, or only Z) enough?
Is there any way to integrate/combine the 3-axis signals into a representative single-axis measures/metric? For example, combining the acceleration signals on  X, Y, and Z into one representative signal.


texts: Can an omnidirectional antenna be used with a directional one?

texts:
I'd like to know if two endpoints in an RF communication system can have different types of antennas, like one directional (yagi) and the other omnidirectional (dipole).

I want to do this because I have an object that I'd like to have RF communication with. I don't know the exact orientation that this object will be in, but I would know its location relative to where I'd be communicating with it (ground station). Is it a good idea to use an omnidirectional antenna for the object, so that it can send/receive signals from all directions, and for the ground station to have a directional antenna pointed at the object? Would this work better than having two omnidirectional antennas at both ends?

Also, just in case this is relevant, the pair of RF modules communicating with each other are gonna be 900MHz Xbee XBP9B-DMST-002.


texts: Differences between preamplifier, instrumentation amplifier and LNA

texts:
I am confused about the definitions of these amplifiers. It seems LNA is used for RF frequency band but I also see people using INA's for receiver.

Why LNA's need careful impedance matching but INAs are not?
Can LNA's be used for low frequency (below 100Hz) high impedance(10kΩ) sensors?


texts: Can a relay be used to power a 3.3 V appliance?

texts:
I'm a programming student and I got into an Arduino class this semester. Here's some backstory behind this question:

I need to make a Bluetooth module switch modes from master to slave and back, but I found out that the module only switches modes by being unpowered then powered again (and doing some specific things). This means I would have to unpower it manually by unplugging its power, but that'd mean it wouldn't be completely automated, so it's a no-no.

Because of that, I'm considering using a relay to be able to power it down then back on again via code, and found some relays that can be controlled by supplying 3.3-5 V.

However, all relays I've seen state that they work on 30/110/220 V.

So, if I use 3.3/5 V to control the relay, and 5 V to power the module through the relay, will the circuit through the relay work?


texts: Microcontroller Unused pins Configuration

texts:
I am having this microcontroller - S32K142 64 pin 5V core voltage
I have a few pins which I don't want to use. While checking the datasheet of the Microcontroller, I couldn't find any information regarding 'on what to do with the unused pins'
So, I checked the reference manual of the Microcontroller. Reference Manual
In the reference manual, Section 12.7.1 page 203-204, they have given the below :

My questions :

I couldn't understand what they are saying on 'what to do, If I have an used pin in the Microcontroller'? Can someone tell me what the Reference manual is recommending me to do incase I have some unused pins? Or is there any other place in the reference manual where they mention on what to with the unused pins of the Microcontroller?

I have read a few answers in this site which advice on what to do with the unused Microcontroller pins. For instance, the accepted answer for this question gives a last solution to leave the 'output pins unconnected, but make the pin output'.

My doubt is, like, which configuring a uC pin, we need to specify the all below information, right?

Whether the pin is Input / Output or Both?
Whether it should be High / Low?
Whether Internal Pull-up Enabled or Disabled?
Whether Internal Pull-down Enabled or Disabled?

So, when the last solution of the accepted answer mentioned 'leave unconnected but make the pin output, what are the pin configurations mentioned above 1-4 do we need to follow for the pin? And why? Please explain in simple terms on why does the solution mentions 'A high level is preferred in case you forgot to switch off the internal pull-up resistors' - Does it mention we need to enable the internal pull-up or disable them?

How do you make a pin to be in the high-impedance state? Like should it be  Output -High Internal Pull-up enabled? or Output-High Internal Pull-up disabled?

Please help to clarify these doubts


texts: Can I use an AND gate before a clock input?

texts:
Can I use an AND gate with a clock input? For example, in the picture below, I have a positive-edge D flip-flop. I'm using an AND gate with the Select_chip input and the Clock input but I'm not sure if this works. When the clock is assigned to a push button, the button will start at high, and then when I press it it will go low to high causing a positive-edge. But with an AND gate, it doesn't seem to work in my mind...

EDIT: I thought about it a little more, let's say Select_chip will be on HIGH always, then if the push button for the Clock starts at high, and if I press the button, the AND gate output will be low since the "Write_enable/Clock" will go low, which inputs into the flip flop changing high to low, and then when the button comes back up, Write_enable is high, making AND gate's output high, therefore changing the flipflop's Clk from low back to high causing a positive edge trigger.

Is my logic correct? I'm not sure.


texts:
I'm trying to figure out what kind of current a single logic gate can supply. I'm looking at this datasheet:

http://www.ti.com/lit/ds/symlink/sn74hc00.pdf

I see in section 6.1 it says "IO = ±25 mA", but that's the section on "absolute maximums". In particular, the device isn't guaranteed to work at that level, it's just guaranteed to not immediately break. (It's not even guaranteed that it won't break; just that it won't break straight away.)

Section 6.3, "recommended conditions", doesn't seem to say anything about current at all. (I'm assuming that current is denoted by symbols containing "I".)

Section 6.5 has "II" (input current?) in nano-amps (...so, the inputs draw really small current?). It also lists "ICC" (total chip package current?) which is only in nano-amps. Presumably the maximum output current must be smaller than this. (?)

In short, I don't see the number I'm looking for anywhere on the datasheet. Am I being blind or something?

I'd particularly like to know what the maximum allowable fan-out is.


texts: Bus communication scheme for large number of devices (255+ nodes)?

texts:
I'm trying to figure out the feasibility of setting up some type of differential bus communication for up to 400 devices outdoors. The main constraints are mainly power consumption, complexity, wire count, and whether something like this is electrically possible (with reasonable bus capacitance/speed/pullups).
The other constraint is that each node should be able to connect ad-hoc in an arbitrary position on the bus. Termination resistors are possible if needed. For example:
+----+     +----+    +----+        +----+
|    +-----+    +----+    +--------+    |
| 5  |     | 0  |    | 1  |        | 4  |
+-+--+     +-+--+    +----+        +----+
  |          |
  |        +-+--+    +----+
  |        |    |    |    |
  +--------+ 2  +----+ 3  |
           +----+    +----+

The distance covered between the farthest nodes shouldn't be more than 15 meters. I'm assuming the bus capacitance will be quite large with 255+ nodes. Does it make sense to include a bus repeater in each node? Would this use unnecessarily high power or significantly slow down communications? High speed communication isn't super necessary, for instance 9600 baud would do the trick.
The microcontroller that I'm using is reasonably fast, but has a single USART and limited free IO pins. So I don't think it would make sense to use something like RS422 and pass through data.
I'm thinking that RS485 half-duplex would make the most sense, paired with a custom protocol based on Modbus. For this application, it seems much simpler to implement in software than CAN, plus making >8bit addressing possible. Does this make sense, or is it unfeasible?


texts: Microphone  spec    sheets  specify a   microphone’s    sensitivity by  displaying  the voltage at  the output  of  the microphone  when    1   Pa  is  applied to  the diaphragm.      If  a   microphone  has an  output  voltage of  2.5mV   @   1Pa,    what    would   its output  voltage be  when    98dB    SPL is  applied to  the diaphragm?


texts:
Hirose offers a Micro-B USB receptacle ZX62D-B-5PA8 as SMT + DIP.
This doesn't really make sense to me, considering that the electronic
contacts are SMD and the mechanical pins are just 0.8mm deep, less than
many PCB. I verified the pin depth in the IGES 3D model.

How is this mounted, i.e. how are the mechanical pins utilized?

Annotated screen shot showing receptacle in catalog page:

Annotated screen shot showing SMT + DIP in catalog's table of contents:


texts: Can the noise of any switching PSU be attenuated if I put linear regulator before the output?

texts:
A friend told me that noise of any switching PSU can be attenuated if I put linear regulator before output. Is that true?

For example, if I want to power a +-12 V op-amp for an amplifier, I can use a switching-mode power supply (SMPS), say, with a noisy 15 V output and then from the SMPS output feed an LM7812 and a LM7912.

Will the output from LM7812 and LM7912 now have very very low noise compared to their inputs?

If this is true, this amazing as there is no need to use a transformer anymore.

Is it really correct that a heavy PSU using a transformer for Class A and B amplifiers is no longer needed?


texts:
I was in class today, and we had a presentation by a student on how tunable lasers are used in fiber optics and change the wavelength. He also explained that by "pump probe measurements" a "sample gets excited and can be measured over time".

Can anyone explain what this means? What is a "sample"? How are "pump probe measurements" useful when dealing with tunable lasers?


texts: Why am I calculating two different Norton currents for a circuit?

texts:
Assume a circuit like so:

simulate this circuit – Schematic created using CircuitLab

Where R1 is an arbitrary impedance X, and R2 is an arbitrary impedance Y.

I can calculate I_norton by finding the short circuit current, which is V/X

Or, I can calculate the thevenin impedance of the circuit, which is 1/(1/x + 1/y) and then dividing V by the impedance of the circuit, I can get I_norton, which would be V*(1/x + 1/y). They aren't the same thing. What am I doing wrong?


texts:
I am intending to make an indicator led circuit which shows the negative 9 V supply is coming to the circuit and led becomes on, but if there is zero volts, the led will be off. I have done this circuit with pnp BJT however i know that if there is 0 volts at the input, led will still on. Do you have any idea about how i can reach my aim? Thank you so much.

This is my circuit;


texts: Why would a 5V input to a 74HC04 pull it's V_CC from 3.3V to about 4V

texts:
I have the following circuit:

simulate this circuit – Schematic created using CircuitLab

The SN74HC00 (from TI) has input clamps, so I am expecting the 5V logic input to be clamped to about 3.3V at pins A and B, and (5-3.3)/1000 = 1.7 mA to flow through the resistor.

In stead, I measure 4.5V at pins A and B, and even VCC now measures 4.5V! (The resulator is probably not happy with this, and is sinking current).

If I remove the SN74HC00 from its socket, the voltage at the regulator's output returns to 3.3V .

Later, I put the SN74HC00 back, disconnected the 3.3V supply from VCC, but kept the 5V input connected. VCC still measured 4.5V .

I also tested this with an M74HC00 (from ST micro) (whose datasheet does not mention clamping), expecting it to break. Same results, and the chip still works with 5V supply.

What is wrong with this circuit? Why does it not clamp the input?


texts: MOSFET always slightly on and other strange behaviour

texts:
I'm trying to control my RGB LED strip with my arduino, using IRLZ34N MOSFETs according to this schematic

simulate this circuit – Schematic created using CircuitLab

I tried it out, everything worked. I soldered it to a circuit board just like that, except for that I used 4 copper wires on the Arduino connections. Everything worked, I unplugged the copper wire from the Arduino and checked back ~3 Days later, then this happened:

The strip was slightly glowing, even when the gates of the MOSFETs are directly connected to ground. Connecting a Gate to +5v made that color glow fully though. That's pretty much my problem, some deeper examining got me those Results:

I desoldered the mosfets and my multimeter reads a resistance of ~290;310;350Ω between Drain and Source. Another strange behaviour is that the conduction seems to go from 0-100% really fast. My LED strip goes from the constant "slightly on"-State to 100% brightness in a matter of some mV. Also strange is that this happens at ~4.7V on the Gate, while my fully functional IRLZ34N gives the strip 0-100% brightness at around 1.5-2V.


texts: Led Matrix multiplexing: sinking/sourcing current + LED brightness

texts:
I am trying to make an 8x8 LED matrix (actually a bigger one, but for now it would be easier to discuss this more simplified version) and I have gotten too confused about a few things concerning the current I need to source or sink as well as the brightness of the LEDs.

For multiplexing I am using two 74HC595 parallel out shift registers each connected to the 8 rows (anodes) and 8 columns (cathodes) respectively. In the case where I have a walking bit (0) for the cathodes, meaning I ground each column at a time and give HIGH to the rows I need to light in that column, I need to sink the current for up to 8 LEDs in one pin. Since the 74HC595 can source/sink up to 25mA per pin and up to 70mA in total, it's not possible to sink the current for all 8 LEDs, neither can it source (to the rows) that current to 8 LEDs. For sinking the current I have found an IC, namely the ULN2803 darlington transistor array, which can sink up to 500mA. So that seems to be fine, considering each LED can handle up to ~20mA of "Continuous Forward Current".

Accordingly, for sourcing current to the rows, I could add a circuit to each of the 595's outputs, consisting of an NPN transistor and a shunt regulator (TLV431) as explained in this video.

This circuit can allow me to provide constant current at each row.

On the other hand there is the problem of LED brightness that comes with multiplexing. Since each column would be on just for 1/8 of the time (1/8 duty cycle) that means I would need to provide more current than the 20mA given for Continuous Forward Current to perceive the same brightness, and from what I've understood I would need to give it about 8 times as much (~160mA). In the specs of an LED there is the "Peak Forward Current" which, depending on the LED, could be ~150mA, but a note says "1/10 Duty Cycle, 0.1ms Pulse Width." The microcontroller I am using (Beaglebone Black with Bela cape) gives me a slow frequency of 2756.25Hz (for 8 bits), which means my pulse width would be 0.36ms 3-4 times more than specified, and also my duty cycle would be 1/8 instead of 1/10. That means that I shouldn't provide the peak current specified but something rather less (in order for the LED to be able to dissipate the heat). Even if it would be possible to provide 100mA to each LED, then the column should be able to sink up to 800mA even though the ULN2803 can sink up to 500mA.

How much current do I need to provide each row so that I perceive a good brightness, considering the duty-cycle and pulse width of my application?
Is the NPN & TLV431 circuit a good choice for supplying constant current or is there a better alternative?
Do you think the ULN2803 is a good choice for sinking the current of 8 LEDs or would I need something to sink more current?


texts: LC filter vs Isolation tranformer for AC coupling of a DAC output

texts:
I'm trying to decide between a few choices for coupling the output DAC of a DDS with the rest of my circuit.

DDS dac's I'm looking at are typically either single-ended or have complimentary current out ports. The signals I'm trying to produce are symmetrical sine waves out of the DDS with a 0 DC level. Single-ended really only has one option (LC coupling for DC rejection). Double-ended DDS's have the disadvantage of using a double ended supply, which I'm trying to avoid for the digital circuitry.

Reading through some application notes, the The complimentary out DDS can either be LC coupled   on one output with an additional resistive termination on the DAC side of the LC with a matching resistive termination to ground on the complimentary output or with a center tapped isolation transformer.

The application notes are sparse on what the relative advantages are of the two so I thought I would ask here. I'm trying to DC filter audio-frequency signals (100Hz->10KHz) with emphasis on maximal DC offset rejection and amplitude envelope symmetricity. Since I'm in the heavily oversampled regime and my application is fairly tolerant to HF noise I'm not really worried about filtering clock noise or other HF spurious noise from the DAC.

EDIT
Per comments, the DDS I'm looking to use is either the AD9837 (single-ended, vout) or the
AD9838 (functionally equivalent, complimentary current out)

EDIT 2

After some looking around I've come up with a third solution, using a simple resistive system for I-to-V conversion and an  instrumentation amplifier (LT1167 potentially) for voltage sensing, would something like this work?

simulate this circuit – Schematic created using CircuitLab


texts: What would I use to regulate raise/lower temperature in an AC 40 watt device's heating element?

texts: It's for a resin burner--frankincense etc--that doesn't have a temperature regulator so it burns too hot. I don't need to know an actual temperature, just to be able to raise/lower the temp'. Thanks.


texts:
I am trying to design a more linear amplifier by using less linear amplifiers in a push-pull configuration. IE run the signal through a 180deg splitter, each leg running through identical amplifiers then recombining through a 180deg combiner.

This should increase the OIP3, OIP2, and P1dB but what happens to the noise figure? I would think it should decrease by 3dB but I'm not sure that is right and am having trouble finding information on it.

Are there any other consequences of doing this with amplifiers besides added costs of more amplifiers?

EDIT:

Frequency Band: HF (3-30Mhz)

Power: Max 12dBm

For example

simulate this circuit – Schematic created using CircuitLab

As seen here in the second half, OIP3 and P1dB should improve by 3dB but no mention of the noise figure and that is what I am trying to figure out.


texts: When shorting power leads to an unenergized bldc motor, it locks up why?

texts: Why do bldc motors or ecm motors lock up when I short two of the leads on n an unenergized motor.  I am a little stumped as to why the unenergized coils are creating a magnetic resistance.   Someone please help me to understand this.


texts: Is it possible (is any IC) that make USB host with STM32? I mean for example UART->USB or SPI->USB converter that make USB host. It sounds strange, I know. Microcontrollers like STM32F103 make USB but only in device mode. I need host mode for making USB communication line transmitter-transceiver, where transceiver will be checking "USB frames". This solution is for analyze influence of noise to USB.


texts: How to implement a continuously scanning multi-channel system in Verilog

texts:
I currently have a multi-channel system where each channel is receiving a pulse at different times. I want whichever channel receives its pulse first to act as the reference to then measure the time difference between the other channels.
I am trying to implement this in Verilog and I do not know how to code the channels (or inputs) so that they are continuously scanning and waiting for their pulses. I need my design to work this way since I do not have prior knowledge of which channel will receive its pulse first.


texts: Should I disconnect appliances if there is lightning?

texts: Is it safe for electrical appliances to stay connected to the socket when there is lighting, or is it better to disconnect them?


texts:
For a project, we are currently looking at how long we could use battery cells, such as the LG 18650MJ1 at maximum discharge and maximum charge in 25°C ambient temperatures.

Basically, in this case, how many cycles can we expect and past these cycles, how long will the battery actually live and be useful, forever? Few 1000s of cycles?

Is there any approximative way to calculate this? Also practical figures to apply to those numbers to estimate by how much life increase if we are at 70% of max discharge and/or charge for example?

Any help or info with respect to how we could have estimate these figures would be very welcome :)

Thank you!


texts: Why is transformer higher voltage primary usually closest to the core and has the shortest loops?

texts:
AFAIK the typical transformer design includes the primary being wrapped closer to the core and the secondary being wrapped atop of primary and so further from the core. Why this way and not the other way around?

This question presumably mentions the design where the secondary is closer to the core and made of thick wide aluminum tape. It's a last mile distribution grid transformer with primary being fed with something like 6 kilovolts and secondary producing something like 110-230 volts (consumer voltage), so the secondary has 30-60 times higher current than the primary and with that current I think it's reasonable to place the secondary closer to the center so that each turn is shorter and the secondary itself is shorter and therefore has lower resistance and lower losses.

The same reasoning should apply to all transformers which lower the voltage - the secondary voltage is usually 10-20 times lower than the primary voltage (110-230 volts primary vs 12 volts secondary is typical) - it's reasonable to keep the secondary wire as short as possible to lower the losses (and save some thick wire).

Yet I've never seen a transformer with a secondary located closer to the core (except in the linked to question).

Why is primary winding usually closer to the transformer center and has smaller coil loops?


texts: Logic function of cmos circuit with feedback

texts:
What is the best way to find the logic equation for f1 and f2 in the static CMOS circuit below. This circuit has partial pull up network made up of just one PMOS and full pull down network with NMOS transistors for each of boolean inputs

My solution to this yields that f1= ~a.~b ; f2 = a+b. But it is incorrect.

UPDATE: My explanation to my solution(possibly incorrect)

Observation

f1 = 0 when either a =1, b=0 or a=0,b=1 or a=1,b=1
f2 = 0 when a=0, b=0
f1 = 1 when f2 = 0 (in step 2)
f2 = 1 when f1 = 0 (in step 1)
No combination of a,b will make f1=1,f2=1 or f1=0, f2=0 simulataneously

Therefore we can conclude that f1 and f2 are always complement of each other.

From step 3, f1=1 when f2 = 0 which in turn happens when a=0, b=0. Drawing truth table for f1

a b f1
0 0 1
0 1 0
1 0 0
1 1 0

This means

f1 = ~a.~b

Similarly, from step 4, f2 = 1 when f1=0 which in turn happens when either a =1, b=0 or a=0,b=1 or a=1,b=1. Making the truth table for f2

a b f2
0 0 0
0 1 1
1 0 1
1 1 1

Therefore,

f2 = a+b


texts: How to find out power capacity of an automotive lead acid battery?

texts:
I have a few 12V lead acid batteries in good condition which I would like to use to power a surveillance camcoder on a remote site. Ultimately that will be solar-powered, but in the meantime I would regularly take battery out for recharge and put a freshly charged one instead.

The hitch is that only up to 25% of the battery capacity should be used before it is taken out for top up, because otherwise it will be dead after several cycles.

My assumption is that if the camcoder power consumption is X and the battery can hold Yh amount of power, then the maximum time the battery should be used before recharging is 0.25Y/X hours. Is this roughly correct?

Now, the main question is how to find what Y is. The only other electrical metric labelled on the battery (apart from 12V) is 730 CCA (cold cranking amps). The battery product code is N70ZZMF if this helps.


texts:
I've often seen a protective diode placed between the Base and Emitter of an n-channel BJT to prevent reverse voltage breakdown (see image attached).
My one question here is: if I have an AC Source connected to 'Ve," can the negative voltage produced accidentally cause the BJT to turn on? I'd like to use isolated GPIO pins between 2.5-5VDC for Vb and Vc, but am worried that even setting these to 'Digital Read' (Open Circuit, or floating) will cause the transistor to turn on if its Ve value swings to -177VAC.
The 2.5-5V signals would be triggered on when the BJT is not connected to an AC Source, and triggered to 'floating/digital READ' when the AC Source is connected to Ve.
Thanks for your help! Can provide more drawings if needed. If there's an issue with using this circuit with a BJT, I could always use an n-channel Power MOSFET instead.


texts:
When controlling a DC motor that is rated at 5V theoretically I can drive the motor in these ways:

5V with 100% duty cycle PWM.
10V with 50% duty cycle PWM.
20V with 25% duty cycle PWM.

Is there a difference between the two? Will using option 2/3 shorten the life of the motor? Would changing the PWM frequency improve the motor lifespan? The reason for doing this is that it is possible to drive the motor much slower with higher voltage.


texts: Preventing under-voltage from ESD strike to ground in floating circuit?

texts:
Consider a circuit like this...

simulate this circuit – Schematic created using CircuitLab

What happens to the voltage seen by the MCU between VCC and GND when this circuit takes a positive ESD hit to the bottom terminal of SW1?

The circuit ground is not connected to earth ground. L1 is parasitic inductance at the very high dv/dt that results from the ESD strike.

Does the MCU blackout?
What is the best defense for this failure mode?


texts:
I am struggling to make a cockpit for my home-made flight simulation.

How can I connect this toggle switch to an Arduino Uno:

Tries:

I connected one end to "Ground" another to "VCC" and middle one to any analog pin. But it turns off the Arduino.

Please help me to connect this switch correctly.


texts: LM555 no output even when trigger is high or low

texts:
Good Day!
I have been banging my head on the desk because I am failing to get the attached circuit work after PCB assembly. I am using Circuit Wizard and my circuit diagram and PCB simulation works when a 6v trigger is used and get the desired output from pin 3.
On the PCB I assembled I get 7.5V with a 6v trigger that's ok because the source supply is 9V and the output is 0 and when the tigger is 0.25V the output is 0 as well. I have check the PCB and verified that the correct voltages accross all pins except pin 3. Why is like this.
Attached circuit.


texts: What is the purpose of this filter, impedance adaptation and virtual ground circuit?

texts:
I encounter this circuit link to a pcb that I used :

with VGND_FIXED defined as :

And AVDD defined as :

As I understand it, the usb provide the AVDD (1.8V).
The AVDD is then used to set the Virtual Ground (VGND_FIXED) at 1.8V pulling up the "floating ground" of the sensor.
Then there is some protection diodes (I'm not sur about this one) an impedance conversion circuit with a first opamp and a second one used as a filter.
My question is, did I guessed well the purpose of this circuit ?
What is the exact consequence of the diodes on the signal ?
For instance, the sensor I used with this circuit sent a voltage between -1V and 1V if I measure the voltage between its signal pin and its virtual ground.
If I plug this sensor on this circuit, what should be the resulting voltage between virtual ground (VGND_FIXED) and sensor2 output (SENSOR2_OUT) ?
The diode should keep it over 0V ? or is it still possible to have a negative voltage difference ?


texts: High current triac control, pcb trace & heat

texts:
I need to drive 30A 380VAC signal with phase control using triac BTA41-600BRG.

BTA41 specifications seems enough but a confusing point is thermal and PCB trace width consideration.

According to online pcb width calculators, 31A current need so much thick traces which is not normal pcb design.

So BTA41 is not good to use in pcb boards with such power, am i wrong?

Should I use BTA40, or is there any way to use BTA41 in circuit with high power (31A, 380V) load, without thermal problem?


texts:
I am using a 74LS377 d-type latch but when I connect Vcc and ground, get a 1-1.2V output on the clock pin! I have 4.9V on Vcc and 0V on the ground and enable' pins. For my minimal example, I have left the inputs and outputs floating for a 'minimal example' but have other examples of this behaviour with microcontroller driven inputs. What could be causing this?

EDIT: Following comments I have connected all other input and output pins to ground. I now have a single chip, with the Vcc connected to 4.9V and all other pins except the clock connected to ground. Still reading 1.2V on the clock pin!


texts: 'bit' type for AVR Microcontroller programming

texts:
I have written a code for 8051 microcontroller, where I used bit type, something like this:

static bit done_flag = 0;    /* bit variable */

bit testfunc (               /* bit function */
  bit flag1,                 /* bit arguments */
  bit flag2)
{
.
.
.
return (0);                  /* bit return value */
}

Now I am porting this to ATmega16 AVR controller. I found that there is no support for
 bit type in AVR.

AVR-lib C User Manual says:

  � Data types: char is 8 bits, int is 16 bits, long is 32 bits, long
  long is 64 bits, float and double are 32 bits (this is the only
  supported floating point format), pointers are 16 bits (function
  pointers are word addresses, to allow addressing up to 128K program
  memory space). There is a -mint8 option (see Options for the C
  compiler avr-gcc) to make int 8 bits, but that is not supported by
  avr-libc and violates C standards (int must be at least 16 bits). It
  may be removed in a future release.

So what should I do now?


texts: MCU freezes when power disconnected from attached HMI

texts:
I have an Arduino (Pro Mini) connected to an HMI display with a serial interface. When the user pushes a button on the HMI screen, it activates a relay attached to one of the digital pins on the Arduino.

For safety reasons, if the Arduino loses communications with the HMI, I want it to turn off the relay. So, when the button has been pushed, it triggers a polling sequence to verify that the button is still being pushed (I'm not relying on the button release event, again for safety). Essentially, the Arduino queries the HIM for a value. If none isn't returned within 100ms, the code times out and kills the relay. As I said, the code works if I pull the RX, TX or Ground connections from the HIM, the code kills the relay and everything keeps working fine. Pull the Bcc from the screen, though and stretching freezer with the relay engaged.

A few notes:

The Arduino and HMI share a common 5V supply, but the HMI doesn't draw power from the Arduino
It's a TTL level serial connection, not RS-232
I don't think it matters, but the Arduino is using software serial on GPIO pins, not the built-in UART.
The serial connection is running at 19.2K

My best guess, and it is a guess, is that the HMI screen momentarily attempts to draw current or dump a load via the I/O lines when it loses it's power source. This appears to be enough to cause the MCU to freeze not sure why.

Any suggestions? Should I have something in parallel with the data lines to protect the MCU?

What could be causing this, and what can I do to overcome the problem?


texts: Microcontroller to Beaglebone data handling

texts:
I have an STM32F0 microcontroller wich is controlling an RS-485 bus interface. The sensors on this bus are providing 220 bytes of data every millisecond.

I want to get the data from the microcontroller to an Beaglebone black so I can store the data in files and FTP them to an server.

The problem here is I have only an gap of 200-300 usec for sending data and I can buffer max 2200 bytes on the STM32.

I tried to send the data over SPI interface, but the Beaglebone can only work master mode so I cant use DMA or a buffer on the Beaglebone. I also tried it with interrupts but they have an respond time form 1-3 milliseconds.
The SPI from the STM is max working on 24MHz which is fast enough to handle the data in the 200 usec.

Does anyone know a way in the form of an hardware buffer or something like that between these two devices. I prefer someone which communicates with SPI.

I tried an SD card already but I think it is to slow.

Thanks in advance,


texts: Recovery time of an monostable circuit using op amps

texts:
I'm having troubles deducting this T(charging). The waveform and corresponding circuit are below. I saw similar deductions, on this circuit, and on other circuits, and I understand we need to use the steady-state capacitor expression Vc(t) = Vf + (Vi-Vf) exp(-t/RC) as the starting point.
I don't truly understand why someone considers Vf/Vi as Vsat, or -Vsat, where the graph never reaches those points.
In this expression in particular, I also need to consider the effect of the diode, and I don't know how to do that.


texts: I study computer architecture and this question came. What is the difference between a virtually tagged and a physically tagged memory system?


texts: What does the black point mean when we are calculate the inductance of several inductors which connected together?

texts:
What does this black point mean?i mean because what reason ,so we will say the inductance  of the circuit below can be written as this,by the way , \$M\$ means Mutual inductance.

Also,i want to ask that Why can the inductance of the circuit below be calculated like this?

\$L_{AB}=L_1+L_2+L_3+2M_{12}-2M_{13}-2M_{23}=3+7+10+(2\times2)-(2\times1)-(2\times 3)=16H\$


texts: Capacitor multiplier does not remove ripple

texts:
I'm trying to build a capacitor multiplier to remove ripple from a power supply. The power comes from a dc-to-dc converter (MC34063). The actual load is a circuit that has multiple modes of operation and it takes 2mA to 20mA. Fortunately enough, it works from 12V to 26V so I do not need to regulate the voltage to a fixed value. I only need to remove the ripple.

simulate this circuit – Schematic created using CircuitLab

The idea of ripple reduction came from here:

https://www.edn.com/design/analog/4350857/Capacitor-amplifier-reduces-ripple-without-dc-loss

The RC filter is 220k Ohm 10uF with a cutoff frequency of 0.072Hz. C2 is a ceramic cap that has 20V DC offset so probably the real capacity is lower and the cutoff frequency is higher, but it should not matter. The 2N2222 has an absolute minimum hFe=35.

Here is what I have measured:

The original ripple of 1.42V was reduced to 1.25V.

Note: in my original question I zoomed in the time scale too much and I was seeing another ripple that was superimposed on the main signal, this was corrected to the above version.

As far as I understand, the transistor is in common collector configuration, and it inverts and amplifies the error between the actual and the "average" voltage. The above image shows that ripple at Vin and Vout are in phase. There is something fundamentally wrong with my design, I just don't see it.

UPDATE This diagram shows: Vin (yellow), V(C2)(blue) and Vout(purple).

The problem seems to be with the voltage at the transistor's base. It should not have 1.2V ripple. I'm still not sure what is happening here.

UPDATE: first of all, the transistor was faulty, it had a short between the collector and the base. That is why there was a "problem" with the voltage at the base. Replaced the transistor and changed the circuit to use the suggested voltage divider instead of a single resistor. R1 = 47k and R2 = 220k. If I remove the transistor then there is 16.8V at Vbase.

simulate this circuit

The basic ripple is now reduced from about 2V to 50mV. But a very high frequency oscillation appeared, as glen_geek had foreseen. This circuit is much more complicated than I tought.

UPDATE - after putting a ferrite bead between the voltage divider and the transistor base, the high frequency noise is still there:

The waveform is changed, it has a bigger spike in it.


texts: Are bluetooth advertise published on one or on at least one channels?

texts:
According to the BLE protocol, when a device is advertising, three channels are used to minimize interference and a channel hopping strategy is put in place.

Probably due to my poor knowledge of radio protocols, I am unable to clearly see if an advertise is transmitted
 a) on only one of the three channels at any given time;
 b) on at least one of the three channels, meaning the same advertise could be picked up twice by a listener.

From my understanding, the observer device only listens on one of the three frequencies at any given moment.

Could anybody help me how with more insight on this matter?


texts: How to build a circuit that generates a sine wave?

texts:
How can I build a circuit to generate sine waves?
What I am working on is building a 555-timer circuit that gives 50% duty cycle square wave, then using a low-pass or band-pass filter tuned to the frequency of the square wave to get a sine wave from the square wave (because square wave consists of infinite number of sine harmonics).

I haven't tested the circuit in the lab but I've used LTSpice to simulate it and the results was acceptable for low frequency (~72 Hz) but bad for high frequency (~72 kHz).
I used this guide from Texas Instruments to build the narrow-band band-pass filter: link.
Here is the simulated circuit:

and here is the result for frequency of 72 Hz:

and for 72 kHz:

The output of the 555-timer is a square wave with 50% duty cycle as wanted.

How can I improve this design to get better results?

Are there other ways to generate sine waves with controlled frequency? I don't want ready-made ICs that do this. I want to build a circuit.


texts: Thevenin equation of a circuit with two voltage sources, one on an open circuit

texts:
I am incredibly sorry, as I'm sure this specific example has been asked before, but I missed the class on it and the professor hasn't yet uploaded the video to his website. I need to know how to find the thevenin equivalent of this circuit:

A lot of the resources online don't seem to cover this specific example, and while I understand how to do it for one source, or sources that are in sequence, the parallel is tripping me up. What really confuses me is how I should be measuring the source connected to the open circuit. I would really appreciate the help.

Since this is for a lab, I need to measure the equivalent resistance, the open circuit voltage, and the closed circuit current.


texts:
simulate this circuit – Schematic created using CircuitLab

I trying to solve a problem which says:
A particular design of a voltage regulator is shown. Diodes D_1 and D_2 are 10 mA units, that is each has a voltage drop of 0.7 volts at 10 mA. Each has n=1. (n is emission coefficient). What is regulator voltage with load 150 Ohm connected?

My way of solving this would be the following: I would find first the current \$I_D\$ through the diodes and the actual voltage with load disconnected by iteration method.
Later I would use this equation to find the change in voltage with the load connected.
$$\Delta V = - I_L (2r_d || 150)$$
where \$r_d=V_T/I_D\$

My question is: is this this a right way to proceed, or should I solve it some other way?


texts: Possible to measure EEG signals with an AM receiver antenna/circuit?

texts:
I'm having trouble understanding the importance of placing EEG electrodes directly on the skin. I used to think the reason for this was to pick up voltage differences between points on the skull, the assumption being brain activity induces voltages on the surrounding head structures including the skin. However, the difference in surface voltages may be due to muscle tension, blood flow, sweat, or other factors unrelated to brain activity. This leads me to wonder if placing "antenna" like electrodes around the head, but not necessarily in direct contact may capture the EEG signal equally effectively.

The only explanation I can find for the skin-touching electrode is the reduction of the 60Hz signal [1] from power lines. Does this mean, if we effectively filter out 60Hz, or go to a place without power lines (e.g. nature), a non-contact eeg electrode may work?

[1] https://www.medicine.mcgill.ca/physio/vlab/biomed_signals/eeg_n.htm


texts:
I have a 2.2kw 400v 4pole 50hz motor. If I connect the motor in star with no load I get a current reading of 3 amps.
If the motor is connected in delta I get a current reading of 56 amps.
What can be the reason for this?


texts: Can I break my BLDC motor by connecting an ESC in the wrong way?

texts:
I've got a brushless DC-motor and an ESC. The ESC has three wires and the motor 8 (of which 5 are for the Hall sensor). The 3 wires of the ESC are not colored or marked, so I just wanted to try some different attachment variations until it works.

If I attach it wrong I would assume it would simply not work. I don't want to run the risk of breaking stuff though. Is it possible that I somehow physically mess up my DC-motor or ESC by attaching it the wrong way?


texts: Building block components for robot sensors and controllers

texts: I'm planning on building a robot using Microchip PIC 16-bit MCUs, which I'm familiar with, and for which I have supporting hardware (demo boards, programmer, debugger, etc). After spending hours online understanding the open-source robotics scene, I've understood that most robotics projects aim to create robots that drive around, hear spoken commands, speak, and the like. I'm currently looking at something a lot simpler. My robot simply needs to read some sensors and move some motors. Is there an online library of open-source building blocks such as motor control, sensor interface, etc, that I can easily utilize on my current hardware? (PIC 24/32 or dsPIC). Obviously the Arduino scene has a lot of more code that can be reused, but I'm not planning on using an Arduino. Or should I? Tell me your views. Any advice is appreciated.


texts:
I'd like to build a cheap and easy op-amp to use with my electric guitar.

The op-amp should input from the guitar's jack and output to a standard "earphone's cable" jack ( not sure about the jargon here ). So that I can plug it into my Hi-Fi's aux channel, or my PC, or just listen on my earphones. A 9v battery would be the preffered power source.

Where can I find schematics for a projet like this?

Also, If I wanted to extend the op-amp to handle basic effects, ( Distortion, Feedback, etc. ) How would I achieve that?


texts:
I have two 9V batteries, an Energizer and a very cheap Gettop that was bundled with some equipment. The Energizer is down to 7.2V, the Gettop is at 9V. If I connect each of these separately to an LED via a 560 ohm resistor, the Energizer's current through the circuit is 7.1mA, while the Gettop only manages 1.1mA. Can someone help me understand what is going on here. Is the chemistry of the Gettop limiting the current? Is this telling me to avoid the very cheap batteries, or only to know their limitations?

Thanks for reading.


texts: Wind turbine protection comparator circuit

texts:
I am trying to design a protection circuit for wind turbine. It suppose to stop turbine rotating when wind speed is to big. I came up with this circuit.

simulate this circuit – Schematic created using CircuitLab

Comparator should be enabled immediately after about 120V is detected and hold it's state for about 15 to 20 minutes regardless of the change in it's input voltage. But I was told that this ADC from micro-controller would be getting incorrect voltage information due to C1 charging through R1 in case of fast change in turbine voltage. What can be done to eliminate this problem. Could simple voltage follower before D1 work?

Second problem is the input offset current in opamp. It can charge C1 and lead to unintended enabling of comparator. Is there a simple way to eliminate this issue? Maybe find a opamp with low offset?

Thanks for help!


texts:
I really want to develop on a gumstix with an e-ink display, but $3000 for a development board is a bit steep for me right now, especially since I just want to get a prototype out so I can see what the market is like.

As a work-around, this is what I have in mind:

Buy a Kindle
Buy a gumstix with a dev board
Hook up the Kindle display to dev board using clever soldering

This is what I want in the end:

Low-power, easy to read screen (text viewing)
Wifi-enabled device
More than 4 GB of persistent storage
Touch enabled device (I can get by without this)
Preferably color, but monochrome is ok

I am really intrigued by the persistence of the e-ink display without using battery...

Is it possible to use the e-ink screen with the gumstix? If not, is there anything else I should be looking into?

EDIT:

I think I can root the Kindle and install my own OS on it, but I won't be able to easily add parts to it (say USB ports, audio ports, etc).  The gumstix is really the way to go.

Legal:

From what I read in the EULA, it is a violation to disassemble the Kindle, but the only thing they can do is revoke access to the Kindle Store and revoke use of any eBooks or services downloaded.  There is no mention of penalties or fines for violating the EULA with respect to hardware.  Since I am not developing this as part of a company, I don't think there is anything they can do legally.

Even so, I just want to know if it can be done with existing hardware and software. If I plan to market something with Kindle hardware components (which I won't), I'll definitely talk to a lawyer first.


texts: Bandpass Filter Design 6Mhz/6.5Mhz Center Approx +/- 250khz passband for ATV system

texts:
I'm looking to build two bandpass filters centered at 6Mhz and 6.5Mhz, with an approximate passband of 250kHz. I want to replace these two filters:
http://www.yoketant.com.tw/yoketant/ceramic-7.htm
LTS6.0MCB
LTS6.5MCB

With a collection of components that I can more easily source from a major distributor like Mouser or Digikey. I'm working on modernizing and shrinking some Analog TV transmitters and receivers in the 23cm band. Here 's a link to the original schematic:
http://tx0rx0.com/?attachment_id=181

The original filters are in the sound transmission system, F1 and F2.
Is this done somewhat easily, or would it be better to try to find those ceramic filters somewhere. I have the book Handbook of Filter Synthesis, by Anatol Zverev, and I can almost piece something together, but I have no way to test it short of building it, and the book isn't terribly clear in some places. Any advice you could give me would be great.


texts: So the brushes in a commutator are fixed and assume a constant polarity, so how does the commutator reverse the direction of current?

texts:
I know this is probably one of the most common questions ever for someone who just started studying DC machines and I would probably get told by someone to just read somewhere and force myself to understand how the reversal of current mechanism thing works as there are lots of sources.
But I honestly can't get a good grasp on how the commutator mechanism works. I got the idea that for slip rings, the direction of the current is periodically reversed such as from positive to negative it becomes negative to positive. I associate these polarities with the brushes.
So how does a commutator fit in? Just because we have two different materials at all times against the brushes, how does that aid in reversing the direction? Is it really vague to just associate the polarities with the brushes because their interaction with the material should mean something and become responsible for the change in direction? How does this exactly work?


texts:
I have a little problem over here. Me and my friend wanted to make a low cost windturbine from scratch for our last school project, we have 24 magnets(size 40x10x4 mm) and 9 coils(1.4mm copperwire and ±56turns).The 9 coils will be in this formation
So we will get 3phase. We asked a friend of he could make the circuit for us, because we do not have the knowledge for it.

I did some research and now I know that we need from the 3-phase generator a Bridge Rectifier to a Capacitor to a "loadingcircuit" to a 12v car battery (or any accu) then back to AC if we get enough power for a electrical outlet or a usb 5V port, something like that. But i don't now what kind of Bridge Rectifier i need and Capacitor etc. The question is what do i need for a circuit that can go from a slow windturbine 3-phase to a 5V usb Output or 12V or the AC 230V eletrical outlet

I don't know if I'm in the right place for this question, but any help will be greatly appreciated.


texts: Pick Up Area / Centroid for surface mount connector

texts:
I'm about to use an SMD connector on a PCB that will be machine assembled.
It is a right angle connector (datasheet).

I can't find where the centroid should be for its package. (I have previously used this connector for hand assembly and I've used other SMD connectors with specified centroids for machine assembly).
These are the drawings that I can find on the datasheet:

I would guess from the last image that the centroid should be in the center of the plastic body (so 7.5mm/2 from the "front"). But it feels wrong to have to guess this. I can always (and I will) double-check with the assembly house if this is ok but I'd like to know what would be a general way of approaching this for unclear packages? (besides "contact the manufacturer") (or if I'm missing the info somewhere or misinterpreting it)


texts:
I have bought a Laser X 88016 two player set gaming device.
When turned, the device on makes an annoying beeping noise every three seconds, no matter what. (As you can imagine you can't really stealth in the game due to the noise.)
Looking on the internet yielded no satisfactory result. The only solution I got was to cut out the buzzer that makes the noise. This way all the other sound effects will be lost, too. (The device can be used with a headset, but the beeping noise will still persist from the weapon part where the buzzer is located.)
I have no experience or education to understand the electronics behind this device. My question is:
Is is possible for myself at home to disable the beeping sound?
I have access to basic equipment if needed.
The PCB of the receiver which I managed to disassemble can be seen here:

Thank you for your time!