texts: GAL 16v8 tri-state independent pin control

texts:
I would like to use GAL chips for a project.
16V8, 22V10, 26V12.
I have read that the tri-state status of a pin maybe controlled individually.
I do not understand how write the equations to individually control the Hi-Z per pin feature, or tell the compiler that is what I have in mind.

This is where I am asking for help & direction.
Many tutorials discuss it can be done, but I haven't found one that illustrates direct control of Hi-Z per pin..

Directly:
How can I use pins (as shown) as an input, to control separately the Hi-Z status of any two or more output pins.

I am using OPAL-Jr for all I've needed before.
data sheet:
http://www.latticesemi.com/Search.aspx?&lcid=9&q=gal16v8&t=480
This is what I am looking to learn, but cannot find as clear as this.

"Each output normally uses a single product term to enable it, so program it like any other signal. – Finbarr"
That is what I don't know.
How to write equations that address individual OE's, not just as a group OE.


texts:
I have this schematic of a quarter of the internals of an LM339 from this site

I want to know what the purpose of the four current sources are in this circuit, and how might they be implemented?

I know current sources can be implemented as the following;

op-amps (not useful to this particular circuit or we would end up nesting opamps within opamps within opamps);
a JFET "constant current diode" (also unlikely, as the LM339 is bipolar);
a BJT current source, which I believe to be the most likely candidate in this device.

What happens to the circuit if the current sources are not present, or the supply isn't able to source enough current? I've tried simulating the circuit - warning, the simulation runs very slowly and fails when you make adjustments to the input voltages, which is either a bug in the simulator or I don't understand what I'm doing (most likely the latter)

I intend to implement this circuit using discrete components for learning purposes.


texts: What is the difference between differential rail-to-rail, push-pull rail-to-rail and rail-to-rail OPAMPs

texts:
I'm loking for an rail-to-rail OPAMP to my project. I need a OPAMP that fed by a 12V and a -5V power supplies can generate an output voltage near these values, at least, near the positive 12V, the value of the negative source is not needed to be reached at the output.

On the digikey's web site, to filter my search , I came across with the following filter:

differential, rail-to-rail
push-pull, rail-to-rail
rail-to-rail

What is the difference between them ?


texts: Multiple if statements in process in vhdl

texts:
I'm not able to write vhdl syntax. But for the exam we must be able to read and interpret it.

The essence of the code is

process{
  if(start)
    c := 0;
  end if;

  if ( c )
     ...
     c := false;
   else
     c:= true;
     ....
 end if;

}

Assuming that c=1 (is a variable) in the beginning. I'm having difficulties interpreting what happens here


texts:
I have some remotely controlled sockets and I would like to rip open the remote control (3v DC) and connect it to the rooms lighting switch (240V AC) so the sockets are triggered when the light is switched on.
Any idea what type of relay I would need to do this (240v trigger with a 3v load) ? Would it be small enough to conceal in the backbox of a light switch?

Thanks!


texts: I use the NUCLEO-L476RG board. ADC runs at 64 MHz and ADC has a 5.33 Msps maximum conversion rate with full resolution

texts:
I need to take 10 samples (10 Hz) per second. How can I set ADC configurations on CubeMX. I use the lowest sampling time (2.5 cycles), but the values I convert and use in ADC change very quickly.
Thanks for helps.


texts: Can an all-tube guitar amp be damaged by flyback voltages?

texts:
Inspired by this question:

https://music.stackexchange.com/questions/66443/how-to-rewire-my-cabinet-properly

And this quote from a comment on the question:

  I've read that with tube amps, this isn't true as you can get flyback voltages when using a cab rated higher than the amp's output...

Assuming a class A or AB tube-based power amplifier with an output transformer and a nominal output impedance of 4 Ohms, would connecting that output to a speaker cabinet with a nominal impedance of 16 Ohms be dangerous the output stage of the amp?


texts: How do I convert the units of a moving magnetic field to volts?

texts:
Copper wire wrapped around an iron core produces current when a strong magnet is moved in its vicinity.

I gather the "magnet movement" part is expressed in units of "weber" (kg⋅m2⋅s−2⋅A−1) or perhaps "tesla" ( kg⋅s−2⋅A−1)

The copper wire of course will be carrying a certain voltage, at some number of amps - dependent on (I think) the number of "turns" of the copper wire, and (I'm guessing) something to do with the speed of the magnet (the unit second-2), and it's strength (the unit kg) and maybe something to do with size (the unit meters2).

Can anyone explain that relationship in a practical (easy to understand in the real world) way?

Like - if I get an N52 neodymium magnet in a 1 cm cube, and I wrap 10 turns of copper around an iron core that's also a 1cm cube - and I move the magnet past the iron (so close it almost touches - so - 0 mm away) at a speed of 10 meters per second... what's my voltmeter and ammeter going to say?

This is not a "homework" question, nothing to do with scams, and I seriously spend ages trying to work this out before asking - please don't down vote my question: if you don't understand something ASK me.


texts: What's the difference between 18 A & 18 Ah on a Battery

texts: What's the difference between 18 A & 18 Ah on a 12 V Battery


texts: Alternative to potentiometer for setting guitar volume

texts:
I'm trying to build something to change the gain of a line- or instrument-level signal very steeply using a microcontroller, to use as a guitar tremolo pedal. I've been looking at digipots but can't shake off the zipper noise associated with those.

One circuit I looked at places a vactrol between the two stages of an op amp. But I don't want to use a component with RoHS problems. So could I theoretically substitute an optoFET?

I understand how a potentiometer works, but I don't understand how the vactrol in the schematic works. (I only have high school physics from 30-odd years ago). Is it working as a current limiter?

There are a few sub-questions there, but the main one is: what other ways (besides a potentiometer) should I be exploring to vary the volume of my guitar?


texts: Interfacing with the kind of LCD found in thermometers

texts:
I have been experimenting with various sensors recently, and one common functionality I have needed with all of them is the ability to see the data being measured.

Thus, I am considering attaching a very inexpensive, compact LCD to each of my projects permanently from now on.

I have decided to use a basic, very compact display like the one pictured below (but no special custom symbols or backlight or anything; just a basic glass display with 4X1 digits or so).

My question is:

What are my most direct options to interface one of these LCDs/glass-panels to a microcontroller, in my case an Arduino/Atmega328? By "direct", I mean inexpensive and compact.

For example, should I:

use an in-between IC that can control the LCD's pins? If so, what is such an IC called, so that I can search for it?
use shift-registers so that I can directly connect my microcontroller pins to all the segments that the display has?
use some other, more direct method?

I am asking for some perspective because I am guessing there is just one or two standard/popular ways of interfacing with them, since these LCDs are found nearly everywhere, in lots of very cheap electronics, and have obviously been around for a very long time.


texts: circuit ~ 7 segment display number didn't run in order

texts:
I am doing a simple 7 segment display circuit using ne555,74ls90 and 7447 ic I connected everything up but the number run 0,2,4,6,8 and did not go to 1,3,5,7,9 and continue... what is the main problem that caused this?
This is my schematic diagram


texts:
I made myself a symmetric power supply for my lab projects using several 78xx and 79xx components. The PCB was ready and I was testing it. I saw that 7905 is giving -12V output.

(See full image.)

(See full image.)
(You see no connection to the middle pins of 79xx elements. That is why -Vmax=-20V is given through the heat-sink.)

I didn't check it twice or thrice; I checked it ten times to make sure that I'm not making a measurement mistake. I measured the voltage on C-5, on the connector pin and on the 3rd pin of 7905. Each time I made sure that I'm taking reference from a -0V point (this power supply consists of internally isolated two symmetric parts, there is also a +0V, that's why I call "-0V" instead of only "0V"). Each time I read a value near -11.96V (there is also a -12 node in the circuit; I'm sure that I didn't accidentally measured it).

There are also other 78xx and 79xx ICs on this circuit. All of them are working perfectly. The only problem is with this 7905 IC. By the way, it is brand new. I hadn't used it anywhere else.

This is my first time seeing a malfunction in 79xx/78xx series. I was very surprised, I thought I could be something I did, so I decided to ask this question. Is this erroneous voltage reading due to something I did? Did this 7905 get broken because of a problem in my design? Or it is just that the 7905 was broken from the beginning (I didn't test it before using). Could it even be that a 7912 accidentally mixed into 7905 basket in the production factory, and then they mislabeled it as 7905?

EDIT:

It came out to be that the 7905 was broken.

I tested the broken 7905 under different input voltage levels to analyze its behavior:


texts:
I need to design a circuit which will count the number of incoming impulses from an external source (the signal`s frequency goes from about 0.05 Hz to maximum 100 Hz) in a preset time interval (that can be be 20, 30, 60 or 120 seconds) and then display this number (on a LCD)

I am planning to use an Atmega mcu with the code written in arduino. My question is: is it worth it to use a external RTC or for this kind of resolution (1 sec) the internal clock is safe to use ( with milis() )?

My goal is to get something as low-cost as possible and with as few components as possible, this is why I`m considering to avoid using a RTC.


texts:
I am building a motor with permanent magnets in the rotor, and I need to pulse the stator coils at the right time, and need to be able to adjust the duty cycle.
My plan was to use not 1 but 2 Hall effect switches (A3144) in an AND gate setup, where the current would only flow when BOTH sensors were ON.
This way, the further I place the sensors apart, the lower the duty cycle becomes, since the moment at which both sensors are ON becomes shorter.
However, I've only been able to create an OR gate setup like this:

Any idea if and how I can create an AND gate using two Hall sensors?
Thanks for the help!


texts: How do we charge a small 12V battery from a large 12V battery bank

texts:
In a youth organization that I am part of we are building a traveling stand alone system, which will be put up on various fairs and music festivals. On one of the festivals there is a wish that we can charge 12V car batteries for people, that they can in turn use for playing music in their camps.

We will have a 1050Ah 12V battery bank. It is actually much bigger than what we wanted, but we got it extremely cheap from a bankrupt company.

We will have smth like 1500W solar panels.

How should we go about charging other peoples batteries?

I guess I should look for a 12V to 12V charge controller? But does that even exist?

I know that there are 12V to 12V solar chargers, but I am not sure how they work from just one battery to another. I guess a 12V battery to 12V battery should be able to lift the voltage.


texts: How to calculate the resistor value of a xenon flash circuit to be a set frequency

texts:
How can I calculate the value of R2 in the following circuit to have the xenon flash (the rate of the charge/discharge of the capacitor) be set at 10Hz?

https://www.eleccircuit.com/xenon-strobe-light-110v-by-scr/
Is this a simple RC calculation? Where R2 is the value we're solving for, 0.1uF is the value of the capacitor and 10Hz is the time constant?


texts:
I want to build a buck converter with p type mosfet.
Specification:
input voltage:24v
Output voltage:12v
I have chosen frequency 20khz,and my inductor value and capacitor value is 1mH and 20uF.

Now all seems to be okay.the problem is i cant drive the pmosfet.I wanted to drive Pmosfet with a NPN transistor.The circuit diagram is given below.Is this okay? If this procedure is okay then what is the problem,why it is not giving me output 12 vol? If the circuit is not okay than what kind of circuit should i use to drive Pmos?

simulate this circuit – Schematic created using CircuitLab


texts: CMOS Output Sensor with a pull up resistor

texts:
The MH251 Hall Effect Switch has a CMOS output, which doesn't need a pull-up resistor. The typical application circuit on the datasheet is as shown:

Since the same design will also be used by other sensors that require pull-up resistors. I am wondering if it is okay to add a pull-up resistor to the output of a CMOS Output sensor. What would be the difference between with and without a pull-up resistor?


texts:
I have a controls homework question I am having trouble figuring out where to start. The questions is Determine whether the system can be stabilized by the control law \$u =  - {G_1}{x_1} - {G_2}{x_2}
% MathType!MTEF!2!1!+-
% feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9
% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x
% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamyDaiabg2
% da9iabgkHiTiaadEeadaWgaaWcbaGaaGymaaqabaGccaWG4bWaaSba
% aSqaaiaaigdaaeqaaOGaeyOeI0Iaam4ramaaBaaaleaacaaIYaaabe
% aakiaadIhadaWgaaWcbaGaaGOmaaqabaaaaa!411F!
\$.

The system is \$A = \left( {\begin{array}{*{20}{c}}0&0&1&0\\0&0&0&1\\0&{ - 4}&{ - 4}&0\\0&{56}&{16}&0\end{array}} \right);B = \left( {\begin{array}{*{20}{c}}0\\0\\1\\{ - 4}\end{array}} \right);C = \left( {\begin{array}{*{20}{c}}1&1&0&0\end{array}} \right)
% MathType!MTEF!2!1!+-
% feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9
% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x
% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamyqaiabg2
% da9maabmaabaqbaeqabqabaaaaaeaacaaIWaaabaGaaGimaaqaaiaa
% igdaaeaacaaIWaaabaGaaGimaaqaaiaaicdaaeaacaaIWaaabaGaaG
% ymaaqaaiaaicdaaeaacqGHsislcaaI0aaabaGaeyOeI0IaaGinaaqa
% aiaaicdaaeaacaaIWaaabaGaaGynaiaaiAdaaeaacaaIXaGaaGOnaa
% qaaiaaicdaaaaacaGLOaGaayzkaaGaai4oaiaadkeacqGH9aqpdaqa
% daqaauaabeqaeeaaaaqaaiaaicdaaeaacaaIWaaabaGaaGymaaqaai
% abgkHiTiaaisdaaaaacaGLOaGaayzkaaGaai4oaiaadoeacqGH9aqp
% daqadaqaauaabeqabqaaaaqaaiaaigdaaeaacaaIXaaabaGaaGimaa
% qaaiaaicdaaaaacaGLOaGaayzkaaaaaa!5787!
\$

My question is how exactly do I test to see if only feeding back two states yields a stabilizable system? From what I can understand, it is possible to see whether a system is fully controllable to imply that it is stabilizable. But how can one see which states are stabilizable?


texts: When is it important to handle reflections in pcb design?

texts: I am watching some videos explaining how reflection can affect a signal and how you should treat these signals as transmission lines to remove reflection. I wanted to understand a more practical example of when terminated a signal is to avoid reflection is important. I have used termination for video signals on a PCB before but what are some other good examples. When should I really be making the effort to have controlled trace impedances (besides video signals) and when is it less important?


texts:
There is a need to send 32 bit numbers between two DSPs in my application.  The receiving and transmitting devices are MCUs supporting 8-bit messages.
Is there a standard way to packetize the data?
Such as:
Message - Payload

0 - start byte
1 - data
2 - data
3 - crc8


texts: counter giving erratic results for frequency measurement using Atmega32

texts:
I am using a photosensor which gives output as a square wave. The frequency of this square wave is being measured using Atmega32A with 1MHz clock. The full scale output of sensor is 500kHz.

The output of the photosensor is connected to pin T1 and I'm using timer1 clock as a reference to determine the frequency. I have a 100 ms delay using software loop after which I read the timer value and multiply by 10 to get the photosensor output frequency.

The frequency values being obtained using oscilloscope are around 50-100kHz. However the frequency values being returned by this code are around 80Hz greater than value measured with an ocilloscope in one setting .If I change the location of the whole setup this constant extra value is changing to another constant . What am I doing wrong?

uint32_t MeasureFrequency()
{
uint32_t freq=0;
DDRB &= ~(1<<PINB1);uint32_t count=0;

TCCR1B |=(1<<CS12);
TCCR1B |=(1<<CS11);
TCCR1B &=~(1<<CS10);            //0.Initalize

TCNT1=0x0000;               //1.Clear timer 0 contents

TIFR &=~(1<<TOV1);          //2.Clear timer 0 flag

//count=TCNT1;
while(TCNT1<1)
{;}//count=TCNT1;}

if(TCNT1>=1)                //3.Check if timer has incremented once
{_delay_ms(100);}           //4.100ms delay

TCCR1B &=~(1<<CS12);
TCCR1B &=~(1<<CS11);
TCCR1B &=~(1<<CS10);        //5.Disconnect timer clock from input

uint8_t i=TIFR;
i = i&(0b00000100);

if(i==4)
{Send_A_Character('v');}

count=TCNT1;            //6.Read Timer

return freq=count*10;   //7.Freq=timer*10

     }


texts: How to interpret op amp minimum supply voltage if the datasheet field is blank?

texts:
I'm trying to find the minimum supply voltage for the LF356N op amp. In the "LF35x" line from the datasheet below, that field is left blank. Same goes for the Absolute Max Ratings (not shown here).

I'm looking for an op amp that will continue to function even as batteries wear down, which is why I want to know the minimum supply voltage at which the op amp will still function.

How should I interpret the datasheet?

EDIT: Datasheet link here


texts: Can anyone help me slow down a 3 speed motor?

texts:
I have a 3 speed single phase A/C motor inside an indoor air-con blower and it runs very noisy (not mechanical/installation issue but just the fan moving air is noisy itself) even on its LOW speed setting. Can anyone advise a way to slow the motor speed down to about 50% of its current speed. I'm not too worried about the MED and HIGH speed setting but if can just do for LOW speed setting would be great. (If slow for LOW, MED and HIGH together is also fine.)

I looked at VFD's but they all seem to be for 3-phase motors. Also someone suggested to join the HIGH and MED speed wires on the motor to the LOW speed and at the controller to put HIGH and MED to Ground.

Thanks in advance for any help. Picture attached.


texts: LED's or OLED for creating specfic colors

texts:
I'm trying to create specific colors given the RGB values (please not that the RGB values go from (0-255)  RGB LEDs use voltage to turn on and the voltage varies from color to color (The red LED in an RGB LED may turn on at 2.7 Volts while the Blue and Green LED in the same RGB LED will turn on at 3.3volts.  I was wondering if any one knows of any LEDs / OLEDs that can use the (0-255) RGB color values

Example of a RGB color I'm trying to create?


texts:
I'm trying to post-process a value computed by a measure statement in ngspice (rev 26) as described in the manual:

.measure tran osct TRIG v(out) VAL=1.65 RISE=10 TARG v(out) VAL=1.65 RISE=11
.measure tran oscf param='1/osct'

osct gets measured correctly but the second one fails with:

Error: measure 'oscf'
no such function as 'param=1/osct'
meas tran oscf param=1/osct failed!

Is this a bug, syntax change, or am I simply doing this wrong?


texts: How do I short D+/D- pads on usb type c connector?

texts:
I am working on a design which utilizes a USB type c connector. My question is what is the proper way of connecting the duplicate D+/D- pads? and do you recommend a specific trace width/ via size?
You can check how I did it in the attached screenshot. I used 8 mil traces and 8/16 mil micro vias.


texts:
So i've been googling displays for the Arduino, and they are all usually small or the wrong shape, but they all seam to have GPIO connectors in the back (shields) that connect directly to the Arduino.

is it possible for me to connect this
to the arduino? and if so, how do i do that?


texts: Which cell balancing method is best to use and implement for low-voltage (48V battery stack) battery management system for E-bike application?

texts:
I would like to design a battery management system for low voltage systems. I am developing a BMS for a 48V, 20Ah battery pack system.

When it comes to battery balancing, I am confused in between resistor based passive and capacitor based active cell balancing method.  Which one is better for my low voltage system application?

Passive cell balancing:
Shunt resistor method: It bleeds the charge through resistors and transistor switch, but the energy is wasted through a resistor as heat.  Even though it is a low voltage battery pack my confusion is will this heat increase the temperature and will this be a problem?

Active cell balancing:
Switched capacitor cell balancing in this method the battery is getting balanced by transferring the charge from high voltage cell to low voltage cells by using capacitor and transistor switch. It is more efficient than passive cell balancing but it takes more time to get equalized and it depends on large voltage variation.

Other cell balancing methods like inductor or transformer based and converter based are more efficient but more complex and expensive for low voltage BMS and as a beginner.

So I am confused as to which cell balancing method is best for a low voltage (48V, 20Ah) system.
Please suggest to me which method is best to use based on my requirements.


texts: Thevenin Equivalent With complex sources

texts:
I am currently studying the thevenin circuit, but I don't know how to calculate it due to the complex sources with dependent source. I've been calculating for more than 2 hours and I can't do it, so I ask for help. Thank you in advance!
Picture's circuit, what is current I_A?


texts: High power (up to 400W) LED DC/DC power supply design considerations

texts:
I am designing a power supply for a high power COB LED requiring 360W @ ~75V from a variable ~60-80V DC input. I have noticed that it is difficult to find switching controller ICs that advertise being able to operate at such high power outputs, and those that do tend to be relatively complex with 40+ pins and a large external BOM (e.g. LT8210).
Previously I designed a much simpler buck LED driver circuit using the AL9910, albeit at a lower power output and single topology, that was as close as it gets to the barebones buck converter circuit, but it worked in that application without any issues. I am now trying to understand what the inherent differences are between the high and low power applications, and whether I could simply use a "basic" buck/boost switching IC with "upgraded" components or if there would be some major problems with this approach.
Some possible explanations for the differences between the ICs that have occurred to me are:

Efficiency - The AL9910's peak efficiency is just above 90%, while the LT8210 appears to be closer to 98%, which is certainly much more important at higher power outputs, though not necessarily a major concern in my application.
Heat - The higher power output generates more heat in the components involved, which at <90% efficiency is very significant, however I would have assumed that this does not have a major effect on the switching controller IC itself if the external components are capable of dealing with it. Although wasteful, I might prefer a larger heatsink and fan than a more complex circuit overall.
Regulation - Tight voltage regulation and noise reduction.
Inductive Coupling - The higher currents involved have a greater effect on signal traces.
More Complex Applications - It makes sense that such high power systems would usually be found in more complex applications, where the additional circuitry for precision, safety, etc, is worth it given the higher cost, so the simple designs are uncommon.

To summarize my question:
What practical limitations or unexpected difficulties exist when increasing the power output of basic external power switch controller ICs beyond that of their recommended "typical applications", and are these limitations (in)directly addressed by more complex controller ICs?
A concrete example for this question:
The LT3757 provides a typical application with a 8V-16V input and a 24V 2A output. Vin is the only pin tied to the power portion of the circuit, the switching MOSFET is external. Is there any reason why a circuit with a 100V 5A output could not be made by adjusting the MOSFET, inductor and feedback voltage dividers, assuming the input voltage is scaled up by an equal amount?
As this is for a hobby DIY project I am not overly concerned about efficiency, safety and cost of components, but I would like to avoid designing and ordering a PCB that ends up not working at all.


texts:
I need to find Vce
Would this be correct way of solving it?
I got 7.551V for Vce


texts:
The voltage across R is Vr. I want to plot I vs Vr on a graph.

Given I = 6k mA. Now, my question is this: wont I vary with varying V1? Did I copy something wrong, or is there a way to plot this?


texts:
I was designing a circuit, when I noticed some unexpected behaviour regarding \$V_{GS}\$ of the PMOS in LTspice XVII.
I have reduced the circuit in order to point out where the problem lies.
D3 was originally connect to another piece of circuit, but as shown below, the weird behaviour can still be reproduced with an unconnected D3.
Few side notes:

For quick reference: the BZX84C10L is a 10V zener
The picture rendered a false spacing in the word "ti me", the real equation for
R1 is R={if(time>2,1G,if(time<1,1G,1u))})

The picture shows 2 simulations.

The left simulation is with the unconnected D3.
In the right simulation D3 has been 'delete'd.

Why does deleting the unconnected D3 give different simulation results?


texts: How does Current relate to Voltage in their behavior in our physical world

texts:
I'm really an electrical noob who tries to understand voltage, current and resistance. I know the formulas and can somehow come up with basic explanations about the physics of electricity. However, what I really don't get is the different effect of current and voltage in a circuit.

From what I understand is that power is voltage times current. I'd like to know some physical properties of a high voltage based power in comparison to a high current based power. So far I only know that high voltage power can be transmitted with much less losses. But what are other physical effects of the two types of power? How does a resistor react on high current vs. high power? I don't understand why 1000v with 1amp has a different effect on resistors than 1v with 1000amp. Maybe someone can provide me with some examples to understand the difference a bit better?

Thanks!


texts: With a 12v circuit feeding 5x 300w inverters over a distance of 15meters. What cable size should I use?

texts:
I have the job of wiring a divelivaboard which is 30m long, and the customer wants 300w inverters in each cabin. He insists on a ring main feeding everything and I went ahead and bought a bunch of cable before discussing anything.

The total length of the ring is around 15-20meters, 5x inverters not including lighting and fans.

I have told him this is not practical, but to have someone else's opinion would be helpful.
 So what size cable should be used( considering the all inverters could be at full demand at the same time)?


texts:
I have a USB Type C notebook charger. I know it can supply 20V with 2.25A for my notebook.

If I have a type-c breakout board, like this: https://www.ebay.com/itm/USB-3-1-Type-C-Female-to-Female-pass-through-adapter-breakout-USB3-1-CF-CF-V1A-/254173573546

And I know the pinout:

What can I do to get DC20V between A1 and A4 (and of course between B12 and B9?)


texts:
I am interested on design and simulate some input stage for a scope, and I want to play polarisation of a BF1105 but I cant get its SPICE model, similar happen with other UHF transistors.

how the manufaturers expect I can design using its parts?


texts: What is the simplest and best device (or circuit) to stop the flow of current in a line when current in another line is present?

texts:
What is the simplest and best device (or circuit) to stop the flow of current in a 3.7V (2A) line when current in another 5V (2A) line is present?

Basically I want to make an UPS using a LiPo battery for a SIM800l, I have an SIM800l module attached to A 3.7V wall adapter but I also have connected the SIM800l to a 3.7V LiPo Battery, I want to stop using the battery when there is current from the USB wall charger.

I do not want to use a standard powerbank since these always use the battery.


texts: transistor negative edge-triggered detector

texts:
This is a circuit I whipped up for an attempt to make a negative-edge triggered detector with inverted output.

The logic needs to be the following:

If input is high, output is high.

If input goes from low to high, output is high.

If input goes from high to low, output goes low for enough time to process data. I'm specifically trying to turn the WR pin on an 82C55 chip into an edge-triggered pin.

This is my circuit and I believe I arranged the parts correctly, but I do not know how to determine the optimal values of each part, except that for R2, I'm going to use maybe 10K to limit current, and I think C2 needs to be higher than C1 to prevent debouncing from the previous chip.

The input is directly connected to a GPIO line of an AT89C2051 microcontroller.

What can I do to make this circuit work at its best without making the speed too slow or too fast?


texts: Specifications for LED strips - power supplies + installing in automobiles

texts:
There never seems to be any talk of using a "LED driver" when using LED light strips in automotive applications.  From my research it seems that LED strips have no voltage regulation and only a voltage dropping resistor.  This mean that the 14.2 typical peek "full alternator charging voltage" could cause some damage to these.   Why does no one seem concerned?

Also I seem to read a lot of double talk about "LED drivers".  Shouldn't these just be common DC power supplies that supply a constant voltage of 12V with an amperage capacity that meets or exceeds that defined as required by the LED strip?

And thirdly, why is there not much talk then of the amperage required by a string of "sticky tape" LED strips?   Is it because the industry only talks in "LED driver speak" rather than "volt and amp speak"?

****** UPDATE AFTER ANSWER 1 BELOW:

I guess what I am asking, and thanks for this detail by the way, regarding the common "roll of LEDs" on a spool that are made and shipped from China that so many people are selling now, regarding these, what I have read is that they use single resistors for each LED in the strip so something to regulate the voltage would be needed.   Now a) is this true, that most of them use individual resistors and b) isn't that really just a constant 12V power supply with an amp rating greater than or equal to that required by the sum of the strips and c) doesn't this mean that the 14.2V commonly reached when an alternator is charging an auto battery at full capacity, that the strip is over powered and will burn out more promptly?   Thanks again.


texts: How to step up voltage on a stompbox or other European device

texts:
I have some musical devices brought from Europe that I would like to convert. I'm tired of having those step-up boxes for each device. I'd like to simply convert once and for all.

The transformer probably are from 220v AC -> 9v DC (or 12v)
I noticed that when I plug them in in my 110v outlet they don't work well.

What is the best way to do this?

Should I buy just a new transformer? (I would like to avoid this because these devices are vintage)

Should I add a DC booster? so in case i want to return to original configuration i can sell them in europe?


texts:
I've got an STM32L073RZ and I'm attempting to write a 4 byte value to the internal 6 KB EEPROM. I'm running MbedOS 5.11.4 but attempting to use the HAL for this. Here's the code:

HAL_Init();

float calibrationFactor = 13000.0;
uint32_t calibrationFactor_bits;

LOG("Store float in 32 bits");
memcpy(&calibrationFactor_bits, &calibrationFactor, sizeof(uint32_t));

LOG("Unlock EEPROM");
HAL_FLASHEx_DATAEEPROM_Unlock();

LOG("Write to EEPROM");
HAL_StatusTypeDef success = HAL_FLASHEx_DATAEEPROM_Program(FLASH_TYPEPROGRAM_WORD, DATA_EEPROM_BASE, calibrationFactor_bits);
LOG("HAL_StatusTypeDef: %d", success);

LOG("Lock EEPROM");
HAL_FLASHEx_DATAEEPROM_Lock();

The program seems to hang when writing to the EEPROM as the function HAL_FLASHEx_DATAEEPROM_Program never returns. As far as I'm aware I'm not doing anything wrong but obviously I must be. Does anyone have any pointers?

EDIT: I've now also tried a code snippet from the STM32L073RZ reference manual, still with the same issue:

*(uint32_t *)(DATA_EEPROM_BASE) = calibrationFactor_bits;


texts: Sending a double type value over CAN Bus

texts:
I need help to send a double value using a CAN Bus.

I am working on a eletronic traction control and i need to send, by a CAN bus, the calculated values of speed of wheels. The problem start when the calculated value is a double type and i need to send it as a short int or int.

Example:

double speed_calculated;

short  value_to_send;

char can_data_to_send[8]; //the function CANWrite sends a vector of char;

speed_calculated = function_to_calculate_correction();

value_to_send = (short)speed_calculated * 10;

can_data_to_send[0] = value_to_send;

can_data_to_send[1] = value_to_send >> 8;

My intention to do is:

If the "speed_calculated" is 10.5, so multiply by 10 and storage 105 in "value_to_send".
As "value_to_send" is a short type, theoretically, i can send 2 bytes.

But, as i am using arduino to test and debug the CAN communication, i am not receiving the correct values.

If i remove the multiplier "*10" of "value_to_send = (short)speed_calculated" i receive only the value of 98 instead 198 that is the correct.

I don't know what i am doing wrong, i've been spending much time searching and testing differents ideas but no one works.

I appreciate the help


texts: Can the ARM processor be switched to unprivileged mode inside handler mode?

texts:
In the ARM documentation it is stated that:

  The processor supports two operation modes, Thread mode and Handler
  mode. Thread mode is entered on reset and normally on return from an
  exception. When in Thread mode, code can be executed as either
  Privileged or Unprivileged.

  Handler mode will be entered as a result of an exception. Code in
  Handler mode is always executed as Privileged, therefore the core will
  automatically switch to Privileged mode when exceptions occur.

But it doesn't specify if I can just switch back to unprivileged mode inside an interrupt handler, or if the processor will just ignore that. I don't have an M3 handy with me to test at the moment so I am wondering if anyone knows the answer or is able to test?

Basically my scenario is I would like to be able to implement asynchronous "event handlers" from user code that are triggered by some hardware activity, but I want these to run in unprivileged mode, the obvious way to do this is to just have a loop like this in thread mode after setting up the kernel:

while (true) {
    __WFI();
    if (event_triggered) {
        run_event_handler();
    }
}

But the downside is that this code will be constantly running and doing the check whenever any interrupt happens, even if no event handler actually needs to run!

Whereas instead I could simply have a purely interrupt-driven design where whenever the kernel does something that (it knows) will trigger a user event, it can raise, say, a low-priority PendSV which then runs them as needed... but of course that would then run in a privileged context. So can I switch back to unprivileged here?


texts: Drawing a Circuit from a transfer function

texts:
I need to draw a circuit from the following transfer function:
\$ \frac{V_o(s)}{V_i(s)}= - \frac{100}{(1+\frac{s}{\omega_{p1}})(1+\frac{s}{\omega_{p2}})} \$

I know how to derive a transfer function from a circuit, that part is easy. But wouldn't going the other way have waaaay more than just one solution. I don't even understand HOW or WHERE to begin. Any ideas?


texts:
The LM317 is rated for "in excess of 1.5A", I have an application that will have a load current of about 300mA. Are there any drawbacks to using this particular IC?

This is my intended setup:

simulate this circuit – Schematic created using CircuitLab


texts: Voltage level translation between +3V and +3.3V

texts:
In a project of mine I have two ICs that work at different voltages.
IC_A at 3V and IC_B at 3.3V and they talk to each other through UART.

In my prototype I use a mosfet with two resistors for each signal in UART( TX, RX ) as a level converter.

My question is:

Could I omit the mosfet and connect them directly or with only a resistor in series? And if yes how to find the resistor's value? e.g.Ohms law?

edit: 3V and 3.3V are the theoretical voltages. When I measure them they are 2.85V and 3.3V...


texts: Can FFC/FPC connectors use in high voltage but lower current applications?

texts:
product page
FVMC 0.2 mm pitch connector supports 50V 200mA which is 10 Watt power,
my application 100V 8mA, can I use above connector in my application since wattage is 0.8 Watt


texts: Would a small scratch/puncture on a lithium battery cause power drain?

texts:
I replaced my phone screen myself and afterwards noticed the battery life was significantly worse.

I scratched the battery slightly getting it out as it was firmly glued in.

Would slightly bending the battery while prising it out or this superficial scratch cause reduced battery life? I am trying to rule out whether it's the battery or something else to justify replacing it.

I've recharged the phone many times since then, and the battery lasts (according to monitoring software) for around 12 hours, whereas before it would last for around 4 days. I put electrical tape over the damage yesterday to see if it would help.


texts:
I am trying to get the hang of op amps and have a few questions about circuits that solve algebra problems.  I would like to solve two problems where \$X\$ is an input voltage and \$Y\$ is an output voltage.  The two (independent) equations are:
$$Y=X/10+11$$
$$Y=X^2$$

For the first, I think the answer would be to start off with a buffer of the input, use a resistor voltage divider from the buffer output and the run the result through a summing amplifier that adds 11.

For the second, I think it would be to run the input through an integrator circuit to get \$X^2/2\$ and then put that through a non inverting amp with a gain of 2.

The input would be between 0 and 5 volts for both of these.

Do op amps solve problems this way?  No present access to a Sim or breadboard but can try this out at a later time.


texts: Why add a second resistor to a circuit in an Ohm's law practical?

texts:
Recently i have performed an experiment on Ohms Law. I tested different resistors in a simple circuit while measuring potential difference and current.

As my group was ahead of the class, the teacher came and added a second resistor in series to the resistor we were testing at the time and we redid all our measurements with this new circuit setup.

My question is, why did he do this and how does this increase accuracy of the results?


texts:
I need a cheap, reliable and easy to build UPS for my raspberry pi server.
The UPS must maintain power for a maximum of 1 hour.
Based on what I found on the internet,I came with two solution. (see diagrams below).

Please rate both and tell me, which one has fewer flaws.

The first solution uses a relay that switches the 5V output from power supply  to 20000mAh bank power. In order not to reset the raspberry when relay switching power source, the voltage for 2 seconds is maintained by the super capacitors. When blackout end, the relay should switch back to the power supply

The second solution uses BMS with three 18650 li-ion batteries, generic 12V power supply and step down converter. In the event of a power failure, the batteries support the power on buck converter. When blackout end, PSU charge batteries and buck converter.

For the first solution i have every part except supercapacitor but i found 3$ deal on Ali. SuperCapacitor
Relay is Omron G6BU-1114P-US-DC12

For second solution i need more parts:
XL4005 5A Max DC-DC Step Down - 1$
XL4005
30A 3S Polymer Lithium Battery Charger Protection Board 3 Serial 12V -  2$
BMS
Barrel jack, 12V PSU, 6 old 18650 battery from laptop, some usb cable lying in my house

In your opinion which solution is beter for 24/7/365 UPS?


texts: Two or more different regulators connected to one battery

texts:
I want to make batteries provide power to both a micro controller (Raspberry Pi) and a 4x4 LED matrix. A simple circuit diagram is shown below. (only one LED is drawn in the fig. But regard it as LEDs in series and parallel.)

In reality, is it possible to connect 7805 and 7809/7812 to the batteries simultaneously? Current up to 16 mA will be required at the LED matrix.

Is there any important things I need to consider?


texts: Fast and memory efficient moving average calculation

texts:
I'm looking for a time and memory efficient solution to calculate a moving average in C. I need to avoid dividing because I'm on a PIC 16 which has no dedicated division unit.

At the moment, I just store all values in a ring buffer and simply store and update the sum each time a new value arrives. This is really efficient, but unfortunately uses most of my available memory...


texts: How to be sure that a ceramic capacitor can manage a RMS current?

texts:
I'm in the middle of a design and I need a capacitor of:

10µF
Rated at 10V
Has to handle a ripple current of 250mA RMS, at 400kHz

Most electrolytic capacitor data sheets give a maximum RMS value for the current. However, I would rather use a ceramic capacitor for this application.
I'm about to use a X7R from Kemet, package 0805, the C0805C106K8RACTU. In its datasheet I've found:

The data sheet indicates a Dissipation Factor of 10%, measured at 1kHz.
I can now estimate the ESR at 400kHz with the usual formula $$ ESR = {{DF}\over{100}} \cdot {{1}\over{2\pi f C}} = 0.004\Omega$$
Dissipated power is then $$W = ESR \cdot RMSi^2 = 0.25mW$$

To check if I'm within range, I should either:

Find in the data sheet some indication of the maximum dissipated power by the device. But this information is not present.
The data sheet does provide the maximum working temperature: 125ºC. To use this information I also need to know the thermal resistivity in ºC/W, but this information is not present.

I would go to another manufacturer, but I have not seen yet any capacitor data sheet providing this information.
How do I know what is the RMS limit for the current in the case of a ceramic capacitor?
EDIT:

I understand that my example is quite in the safe zone. However, my question is more general: Where does the safe zone end, according to the datasheet?
I've seen this similar question, but there is no definite answer. One comment propose to check the data sheet (and this exactly the sense of my question). One answer says to compare the dissipated power with a Pmax value. Again, in ceramic capacitors, I can't find this kind of information.


texts: Which would be cost effective, a display with graphics controller or without graphics controller?

texts:
I am working on a touch screen display on stm32.

I found some evaluation boards like mikromedia-7-stm32f7 and
stm32h753i-eval

Mikroelectronica uses the external controller SSD1963, although the MCU has a built in LCD-TFT controller.

Why do they use the external graphics controller SSD1963?


texts: Why is the Active/Real Power Rating So Low for This Relay?

texts:
I'm trying to select a relay for a IoT project that will control a water boiler.
I took a look at the HF32F-G relay, but some of the specifications in the datasheet weren't making any sense to me.

Specifically, the given contact rating for a resistive load is 10A@250VAC, which naturally translates into the specified max switching apparent power of 2500VA.

However, the specified figure for max switching real power is merely 300W, which doesn't seem to agree with the given contact rating for a resistive load of 10A@250VAC.

Can anyone shed some light on this apparent discrepancy?


texts: Will a 24 volt buzzer work with 19 volt supply lines?

texts:
I'm fixing up an apartment condo and opened the doorbell buzzer/door unlock wallplate looking to install a new wallplate and button that isn't caked in old paint.  When I slid the housing out, the fragile wires on the buzzer broke off.  I want to replace it with something from this century.  Almost all buzzers I can find are DC but I have found some 24 vac ones that might work.
This is a 3 wire system.  Red and white have 19v and work with the button in my unit to open the door for guests.  There is no transformer in my apartment.  The buzzer worked from the same red wire and used a green wire for neutral.  I tried attaching a cheap door chime to the red and green wires and it works fine, but I would prefer not to have mount an additional item on the wall. http://www.galco.com/buy/Edwards-Signaling/1065-G5 is a likely contender


texts: Why ATMega328 can't run SPI at full clock speed

texts:
Two part question:

In the datasheet on page 168, the best SCK frequency one get get on SPI is \$\dfrac{f_{osc}}{2}\$, why can't this be \$f_{osc}\$?
Also from the datasheet: "When the SPI
is configured as Slave, the SPI is only guaranteed to work at \$\dfrac{f_{osc}}{4}\$ or lower". Why?


texts: Will MCP23017-E/SP be compatible with an ATtiny85? ATmega328P?

texts:
I mainly want to also be able to use the same I/O expanders with ATTiny85 projects since those chips have limited pins.

I will be doing the main prototyping on an ATmega328P ( Arduino UNO ).

Given that both of these are 8 bit, how do they deal with 16 bit resolutions from the MCP23017?

MCP23017/MCP23S17 Spec Sheet


texts: How do they power 150 LEDs from a TV USB Power Source?

texts:
The product concerned here is : 5M Led Strip
LED Strip of 5 Metre with 30 LEDs per Metre.

The data sheet for the LED used : SMD5050

And I know(Not checked physically, just read) that TV USB are capable of providing 5V 500mA Output.

Considering only the RED Color LED what I understand is  I can connect 2 LEDs in series since Voltage Drop(Max is 2.4) with a 10-30 Ohm resistor.

I can connect 25 such strips in series parallel to each other as Forward current of LEDs are 20mA.

That makes a Total of 50 LEDs only from the TV USB Power if I only intend to use it for RED colour.

How can they connect 150 LEDs to a TV USB Power. Am I missing something or Are they other ways to connect LEDs? Or do they put current limiting resistor of value thrice than needed to accomodate all the LEDs? Or is my calculation wrong?


texts: Is this how you PCB trace a 50 ohm impedance transmission line for an RF antenna?

texts: I am trying to use LoRa with a RFM95W module. I added this 3mm trace on the opposite side of the ground plane to try to create a 50-ohm impedance. I want to use a wire antenna to J4. I also included an optional ufl antenna connector. Does this look like the correct way to lay this out? Is there enough of a cutout of ground pour around the trace?


texts: Rectified current transformer output is asymmetric

texts:
I'm using a current transformer (CS4200V-01L) to measure the current in a half-bridge. I'm facing an issue where the signal out of the current transformer is asymmetric, almost as if the current transformer is DC biased. This is the rectified signal, measured across R42:

Below is the relevant circuit extract. The signal is rectified, fed to the burden resistor (R42), low pass filtered and fed into a microcontroller in the range 0 to 3.3V.

How come the signal is asymmetric? I figured that the current transformer operated as a floating current source - my simulation seems to think it is too.

Obviously there's something else going on here. I thought the transformer may be saturated but the current doesn't look to be higher than 20A and the transformer has a maximum sensed current of 35A. Also it does the same thing at 10A, and I don't think that would explain this problem anyway.

Any input would be appreciated.


texts:
We just started using OrCAD Capture CIS at the company I work for, and we were wondering how can 'treat' interchangeable parts.

When we migrated our current library we found that we had several caps of the same value and parameters from different MFRs.

Some of them are a bit more expansive, and some are obsolete, is there a way to hide them from the CIS search and just keep the one we want to use from now on, or do we just have to delete them from the catalog?

This is basically a 'best-practice' question regarding OrCAD CIS, any help and advice would be much appreciated!

Thanks in advance


texts: I'm having trouble understanding this circuit. Can someone help me get through it? I'm trying to understand what the signal is doing from start to end but keep running into electrical deadlocks.


texts: Capacitor charging-like signal on SPI port's MOSI line

texts:
I'm using Texas Instruments Tiva C Launchpad to communicate with a micro SD and micro SDHC cards. The development board uses TM4C123GH6PM chip and I'm using TI RTOS's FatFS example for the Launchpad to access the card. In the example, port SSI2 was used for SPI communication. The SSI2 port is connected to port B's pins. The port is connected using jumper wires to a micro SD card adapter positioned on a breadboard.

Here's the adapter's pinout:

GND - to launchpad's ground
+3.3V - from Launchpad's regulator
Card detect - not connected
DATA2 - not connected
Chip Select - connected to SSI2
MOSI - connected to SSI2
Clock - connected to SSI2
MISO - connected to SSI2
DATA1 - not connected

In order to get the FAT example to work, I had to make some modifications to it, since it obviously wasn't tested.

In file EK_TM4C123GXL.c I made following changes:

const SDSPITiva_HWAttrs sdspiTivaHWattrs[EK_TM4C123GXL_SDSPICOUNT] = {
    {
        SSI2_BASE,          /* SPI base address */

        GPIO_PORTB_BASE,    /* The GPIO port used for the SPI pins */
        GPIO_PIN_4,         /* SCK */
        GPIO_PIN_6,         /* MISO */
        GPIO_PIN_7,         /* MOSI */

        GPIO_PORTB_BASE,    /* Chip select port, in TI's example was PORTA_BASE */
        GPIO_PIN_5,         /* Chip select pin */

        GPIO_PORTB_BASE,    /* GPIO TX port */
        GPIO_PIN_7,         /* GPIO TX pin */
    }
};

and

Void EK_TM4C123GXL_initSDSPI(Void)
{
    /* Enable the peripherals used by the SD Card */
    SysCtlPeripheralEnable(SYSCTL_PERIPH_SSI2);

    /* Configure pad settings */
//This was original TI's code
//    GPIOPadConfigSet(GPIO_PORTB_BASE,
//            GPIO_PIN_4 | GPIO_PIN_7,
//            GPIO_STRENGTH_4MA, GPIO_PIN_TYPE_STD);
//
//    GPIOPadConfigSet(GPIO_PORTB_BASE,
//            GPIO_PIN_6,
//            GPIO_STRENGTH_4MA, GPIO_PIN_TYPE_STD_WPU);
//
//    GPIOPadConfigSet(GPIO_PORTB_BASE,
//            GPIO_PIN_5,
//            GPIO_STRENGTH_4MA, GPIO_PIN_TYPE_STD);//Used to be PORTA_Base, but this didn't work
    GPIOPinTypeSSI(GPIO_PORTB_BASE, GPIO_PIN_4 | GPIO_PIN_5 |
                                        GPIO_PIN_6 | GPIO_PIN_7);//Copied from SPI-loopback example

    GPIOPinConfigure(GPIO_PB4_SSI2CLK);
    GPIOPinConfigure(GPIO_PB5_SSI2FSS);//added
    GPIOPinConfigure(GPIO_PB6_SSI2RX);
    GPIOPinConfigure(GPIO_PB7_SSI2TX);

    /*
     * These GPIOs are connected to PB6 and PB7 and need to be brought into a
     * GPIO input state so they don't interfere with SPI communications.
     */
    GPIOPinTypeGPIOInput(GPIO_PORTD_BASE, GPIO_PIN_0);
    GPIOPinTypeGPIOInput(GPIO_PORTD_BASE, GPIO_PIN_1);

    SDSPI_init();
}

After this, the code managed to write a file to the card correctly.

Now comes the actual question itself:

While I was probing the communication between the microcontroller and the SD card, I noticed that on the MOSI pin, there's a waveform that reminds me of a capacitor charging.

Red channel is MOSI and yellow channel is MISO.

At first, I thought that it could be the MISO line charging the parasitic capacitance between the MISO and MOSI pins on the development board, since those two pins are next to each-other. After probing some more, I came to the conclusion that this is not the main cause of the phenomenon.

Here we can see that there is still some charging action on the MOSI line, even thought the MISO line is low at the moment.

On the SD card adapter itself the clocl line is in between the MOSI and MISO lines, so I thought that it could be causing the issue, but while the MOSI is getting charged, the clock line is low as well.

Red is the MOSI line, yellow is the clock.

Here's a shot of the smaller "triangle" and the clock line:

During all this, the Chip Select line is held low, so it could not be charging the master out pin.

So any ideas what could be causing this type of behavior?


texts: How to determine the force of a solenoid based on inductance

texts: I'm looking to potentially build my own small solenoids, I thought perhaps that I could take an Air core inductor, a spring, piece of plastic, and conductive core and build my own. Is there a way to determine  force based on inductance and current (or power).


texts: Powering a large DC motor from the mains

texts:
I scavenged a 220 volts DC motor from a large photocopy machine.

How can I best get a suitable 220 volts DC supply when our local main supply is 240 volts AC?  Since the voltages are so close is there a cheap way to convert type of current on a one-to-one basis like this?


texts: Arduino-controlled slot car set - Why are my MOSFETs burning out?

texts:
I'm attempting to control the speed of a slot car using an Arduino and a MOSFET.

I'm new to MOSFETs, however, and while my setup works for a moment, eventually the MOSFETs (N-Channel) open up, and they no longer regulate the car's speed.

I'm using this slot car set and this MOSFET.

The wiring is like this.

The slot car controller ground and the MOSFET source are connected to the Arduino's GND. The Arduino control line is connected to the MOSFET gate and the Arduino GND through a resistor. The other line from the slot car runs to the MOSFET drain, and I put a diode over the rails of the track to prevent reverse voltage spikes.

I'm able to fluctuate the speed of the car for a while, but eventually, the MOSFET goes out and no longer works. The slot car power supply is 17V DC.

Here are some more photos: http://imgur.com/a/iRL7D

What could be causing the MOSFET to burn out? The car flying off the tracks, maybe? Or, could it be heat? Would a heat sink attached to the MOSFET eliminate my problems? Do I have the right MOSFET?


texts: i'm having trouble with my distortion pedal.  I believe I've fixed the input problem with the last design, but it still has the same problem.  Currently, any distortion comes from the second op-amp, and not the clipping diodes like it should.  I know this, because the distortion doesn't change when I disconnect the didoes.  I'm really confused, because I believe it all works on the spice sim, so maybe I've done the sim wrong?  Otherwise, is there anything inherently wrong with the design?  should it work as expected (clip the signal via the diodes)?  The first op-amp is the buffer stage which adds the offset, and the second adds gain for the diodes to clip.


texts: Controling torque generated by DC motor?

texts:
I am new to this field so spare me if I am asking something wrong.

I have a battery of around 48 volts and a dc motor of 2hp. So I was thinking is there a way to increase the torque generated by the motor when I need it and increase the speed of the motor when needed by changing the voltage being transfered to it by installing a transformer.

Please explain it to me and if I am wrong, it will be very helpful if you could provide some useful reference as I have to enter an electric cart making competition in few months thanks.


texts: Kirchhoff's Voltage Law Yields More Variables Than Equations

texts:
When I try to solve this problem I get three equations:

VR3+VR5=20
VR1+VR3=-20
VR1-VR5=-40

The problem is that you can obtain 1. by subtracting 3. from 2. so you actually have only two equations with three variables. What am I missing?


texts:
I want to be able to detect when a 8V signal goes low and send a signal to a raspberry pi over GPIO. A java app will be listening on the GPIO pins for any changes.

I would check if the voltage drops via the pi directly, but I need to check 10 signals and do not want the pi (and 3v LDO voltage regulators) absorbing 3v per signal constantly while dissipating the other 5v. Dissipating 50v and absorbing another 30v will probably produce enough heat to melt the pi without some major cooling.

I have seen examples using optocouplers or NPN transistors, but need to get the output signal to within the pi's tolerances of between 2.0v and 3.3v.


texts:
I have a very back to basics question.
I've been using a 5v relay with the raspberry pi. The relay trigger is connected directly to an output pin and the other side is connected to the ground of the board.
I've been counting on the internal coil resistance to serve as over-current protection, and so far in small application it worked out fine. But I've have been told that this is not a good idea and i might damage the board if the output is held HIGH for too long. Any confirmation on this would be appreciated.


texts: Unable to communicate with a deice over rs485

texts:
Possible Duplicate:
  No response from device when using rs485

I've been stuck on this issue for quite some time. I am trying to use an arduino to communicate with another device using RS485. The problem is that I can see the data being sent but, the device does not reply at all. Here's the break down so far:

I am using a hardware serial port and a Max487 rs485 transceiver
which is attached to a custom sheild.
I am able to get the device working over RS232 using a library I have
written so, I don't believe its a software issue.
I have also been able to communicate with the device using a usb to
rs485 converter. This wasn't attached to my arduino, I sent the data
using realterm. So, i don't think its a problem with the device.
I am using a sheilded cable with 2 twisted pairs. One pair I am using for ground, the other for  the Non-inverting/inverting signals. The cable has an impedance of 120Ohms. My cable is about 11m long.
I have a 120 ohm terminating resistor on my pcb and have enabled the biasing termination on the device. (The iverting line is 5V biased, the non inverting is at 0v).
When I look at the traces, I can see that all the data is being sent, along with the parity and stop bits. I have attached a picture of the 2 traces and the result of (non inverting line - inverting line)
I am writing !(Receiver Enable) and Driver Enable pins high when transmitting, and low as soon as the transmission is complete.
When I couldn't get it working with my first sheild, I made another. Unfortunately, I am still haing trouble.

In summary, I don't think its a software issue. I've done a lot of reading but, haven't managed to find anything that helped. Does anyone have any suggestions for what could be preventing the device from responding? Any help would be greatly appreciated

Thanks in advance


texts: design a 8 to 3, valid output - priority encoder with AND,OR,NOT Gates

texts:
I'm trying to implement a 8 to 3 priority encoder which worked quiet well.

My function for the three outputs are:

$$A_0 = e_1 + e_3 + e_5 + e_7$$
$$A_1 = e_2 + e_3 + e_6 + e_7$$
$$A_2 = e_4 + e_5 + e_6 + e_7$$

Now I want to add an output which shows if more then one input is active. If only one input is active the valid output should be 1 otherwhise 0.

I don't know how to implement my valid function with AND, OR and NOT gates.

Does anyone have a hint for me?

EDIT:

This is a draft of the valid function:

V(e7,e6,e5,e4,e3,e2,e1)=
if      e7=1 and e6=0 and e5=0 and e4=0 and e3=0 and e2=0 and e1=0 then return 1
else if e7=0 and e6=1 and e5=0 and e4=0 and e3=0 and e2=0 and e1=0 then return 1
else if e7=0 and e6=0 and e5=1 and e4=0 and e3=0 and e2=0 and e1=0 then return 1
else if e7=0 and e6=0 and e5=0 and e4=1 and e3=0 and e2=0 and e1=0 then return 1
…
else if e7=0 and e6=0 and e5=0 and e4=0 and e3=0 and e2=0 and e1=1 then return 1

The truth table looks like the following:

The problem with the truth table is that I'm not able to create a kv diagram with 8 variables.


texts: Control of 4 pin cpu fan with 3 pin socket and ...?

texts:
I have a problem with controlling my cpu fan speed since it has a 4 pin connector and the socket on my motherboard is broken (transistor connected to it has burnt).

I have it connect at the moment to 3 pin socket but I would like to reduce its speed somehow. I know I can apply a  transistor or a potentiometer on the 12V rail that goes to the fan but is that a good idea or you have anything else to suggest to me ?


texts: I'm looking into the SSP1117-5.0V voltage regulator, but can't find if Fin is connected to any other pin.


texts: Is this design feasible? Door-open warning light circuit with safety interlock switch and general SPDT relay on wall voltage (120VAC)

texts:
I am trying to design a very simple system for my workplace that turns on a warning beacon light when a swinging door is opened. My current thinking is to use a non-contact magnetic safety interlock switch to actuate a relay, which will switch the circuit connected to the warning beacon light.
The image below details my current plan for the circuit design. Links to the specific components are listed below the image. V1 is standard US wall voltage at 120VAC. RLY1 is a general-purpose SPDT relay rated at 10A 120VAC. SW1 is a normally-open magnetic non-contact safety switch with 120VAC operating voltage rated at 3A max. LAMP1 is an industrial high-intensity LED beacon light rated at 90-240VAC with 50mA current consumption.
When the door is open, the magnetic safety switch is not actuated and therefore open, so the relay coil is not energized. Therefore the NC contact of the relay is closed, powering the light (shown in the image).
When the door is closed, the magnetic safety switch is actuated and therefore closed, energizing the coil. Therefore the NC contact of the relay is open, meaning the light is not powered (opposite condition of the image).

RLY1, general-purpose relay: https://www.galco.com/buy/IDEC/RH1B-UT-AC120
SW1, magnetic safety switch: https://www.galco.com/buy/Edwards-Signaling/111-4Y-06K
LAMP1, warning beacon light: https://www.productsforautomation.com/meltric-ms86trffr-86-red-beacon-light-p/ms86t-rff-r.htm
Is this design feasible? Do I need to add additional components? Is there a more simple approach I am overlooking?
I am worried about putting only the relay coil and the magnetic safety switch in series with wall voltage. I am fairly confident that the other side of the circuit will be fine (wall+120VAC > relayCOM > relayNC > LAMP1 > wallGND).
P.S. if this is a stupid or previously-answered question, please forgive the Mechanical Engineer that asked it. I have been incessantly researching this for the past 12 hours (even digging through various old textbooks) and am at my wit's end.


texts: what are the implications of using a 45kW ACS580 ABB VSD on a 22kw induction motor?

texts: What are the implications of using a 45kW ACS580 ABB VSD on a 22kW induction motor?


texts: What is the nature of the signal given by the needle of a turntable?

texts:
I have a small children's record-player. I'd like to modify it so that it can also play music from an SD card from my phone from the same speaker. After opening the device I see that the output from the needle which has two wires positive and ground goes into what I assume is an amplifier board. I have a SD card mp3 player board which has audio out that can be attached to speakers running at 5V. Should I hook this to the speaker in the player? or should I run it through the built-in board first?

Is the signal from the needle basically the same as the signal going to the speakers just softer?


texts: How to determin the load requirement for 24V DC power supply

texts:
I'm working in automotive industry, I got a project to add extra hardware to  particular line. hardware actually requires 24v 70w. Now, we have a Power supply unit "power one he-24V-7.2a" in the cabinet. For which "n" number of sensors, limit switches, grippers, power supply for I/o modules of plc, etc are connected.
I Couldn't exactly find what are all the devices are connected for 24v Power-supply hardly sensors. But lot of sensors. I don't have any document to check the load requirement of this particular line. Only I can see is Output of the power supply is connected to 8A fuse.

By considering this I'm thinking the load requirement of this line might be
=24V*8A
=200W approx.
is this 200W is load requirement of line?

If I add extra hardware(24v, 70w) to this powersupply. Do my power ratings and voltage ratings differs. Could some one explain me exactly how to deal.

thank you
I'm new to this world ur help is appreciated


texts: Is it possible to cool an acrylic sheet with a Peltier (thermoelectric cooler)?

texts: I am trying to create a cooling stage that can maintain 4 degrees Celsius however the stage must be optically transparent. Will a Peltier cooler be able to cool an acrylic sheet, or will the low thermal conductivity cause the Peltier to overheat without cooling?


texts: High current through Mosfet in boost converter?

texts:
I want to make a simple boost converter to step 5V up to anywhere from 30V to 65V
I want to be able to vary my duty cycle to be anywhere between there.

Did I chose a correct mosfet? I would like a mosfet in a really small package but I am not sure what to choose
How do I lower the current through M1 so I am not wasting unnecessary amounts of power
Should I opt for a BJT instead? See last picture

L is the 7447709102 WE-PD


texts: Routing Guidelines for Analog Video (VGA, RGsB, PAL)

texts:
I am currently into the design of the analog video IN/OUT. Basically I have a 3U PCB on which the encoder/decoder ICs are present, that converts the digital video to the analog RGsB (RGsB OUT) and PAL out, and from board-to-board connector this signal goes to the backplane where the RGB connectors are present and connects to the RGB display. Similarly from the VGA connector (VGA IN) on the backplane, the analog signals are coming to the main card from the backplane via board-to-board connector.
Now my concerns are:

What precautions need to be taken care while designing the circuits that involves the video signals?
Routing guidelines as the traces are routed long way from the main board to the backplane and then to the connector where the display will be connected.
Do we need to use any sort of amplifier ICs on the analog signal path?

It would be  great if I get good techniques/methods that need to be followed while designing the board/PCB with analog video In/Out, where a backplane is involved and the connectors are far from the encoder/decoder.


texts:
I have absolutely no electronic knowledge and need clarity.

I have a fuel gauge and sender unit that are reading at different resistances at the sender and at the gauge. Full at sender is 0 ohms (correct), whilst it is 192 at the gauge, and when empty 340 at sender and +- 540 at gauge. It should also be 0 and 340 at the gauge.

I was planning on fitting a 0 -10k potentiometer inline between the sender and gauge, but I cannot see how that can reduce the resistance at the gauge. Surely it will increase the 192 or 540 by between 0 and 10K? Am I missing something here?


texts: Will a standard 9V alkaline battery (300mAh- 400mAH) be able to supply 2.5A for 5-10 second at a time?

texts:
For example, I have a motor that needs a surge of 2.5A for a short amount of time from a 6V power supply.

Will any 6V battery able to supply that current? Even if let's say it has only a 500mAH. How does AMP rating matter when talking about this?


texts: How to trigger a Low-level relay with PIR sensor?

texts:
I have a SRD-12VDC-SL-C relay with this configuration: https://www.iotwebplanet.com/product/relay-module/
And I want to trigger it with PIR Motion Sensor Detector Module HC-SR501
https://robu.in/product/pir-motion-sensor-detector-module-hc-sr501/
The problem with direct connection to PIR is that the trigger output of PIR is +3.3V however the relay needs low or (zero) voltage in order to switch. I do not see how the relay in the link above can be put into High-level trigger.


texts: In order to create a photovoltaic cell all I need is a photodiode connected parallel to a capacitor right?


texts: How do you decide on having more than two layers to have on a PCB?

texts:
I just started writing my bachelors thesis. I have been working as a junior hardware designer for a little less than a year now. All the boards I have designed until now have 2 layers. For my thesis I will be designing a board around the new Raspberry-Pi compute module 4, so I would like to know if I should base my design on a 4 layer board.
1.st Question
I see that for RF, low noise, high speed etc. applications 4 to 6-layer boards are used. I haven’t taken a lecture on the subject yet and most of my PCB knowledge is self-taught outside of the university. I would really appreciate it if someone could explain why and when to use more than 2 layers for reasons other than board complexity. If you could link maybe a book or lecture to the subject it would be even better.
2nd Question
I vaguely understand that for high speed boards like computer mother boards, multi-layer boards are used. Referring to my 1st question, why? Would I need to make my board multi-layered? If yes, how should I go about my layout and copper regions? Are there any mystery rules that I should take into account other than respecting the datasheets of the ICs I use?


texts: How to include memory files (hex, mif, dat) when running simulation using VUnit?

texts:
here is an excerpt from my rivierapro_setup.tcl generated by Qsys:
# ----------------------------------------
# Copy ROM/RAM files to simulation directory
alias file_copy {
  echo "\[exec\] file_copy"
  file copy -force $QSYS_SIMDIR/submodules/SPRINT_OSI_S_mem_if_ddr2_emif_0_s0_AC_ROM.hex ./
  file copy -force $QSYS_SIMDIR/submodules/SPRINT_OSI_S_mem_if_ddr2_emif_0_s0_inst_ROM.hex ./
  file copy -force $QSYS_SIMDIR/submodules/SPRINT_OSI_S_NiosII_cpu_bht_ram.dat ./
  file copy -force $QSYS_SIMDIR/submodules/SPRINT_OSI_S_NiosII_cpu_bht_ram.hex ./
  file copy -force $QSYS_SIMDIR/submodules/SPRINT_OSI_S_NiosII_cpu_bht_ram.mif ./
  file copy -force $QSYS_SIMDIR/submodules/SPRINT_OSI_S_NiosII_cpu_dc_tag_ram.dat ./
  file copy -force $QSYS_SIMDIR/submodules/SPRINT_OSI_S_NiosII_cpu_dc_tag_ram.hex ./
  file copy -force $QSYS_SIMDIR/submodules/SPRINT_OSI_S_NiosII_cpu_dc_tag_ram.mif ./
  file copy -force $QSYS_SIMDIR/submodules/SPRINT_OSI_S_NiosII_cpu_ic_tag_ram.dat ./
  file copy -force $QSYS_SIMDIR/submodules/SPRINT_OSI_S_NiosII_cpu_ic_tag_ram.hex ./
  file copy -force $QSYS_SIMDIR/submodules/SPRINT_OSI_S_NiosII_cpu_ic_tag_ram.mif ./
  file copy -force $QSYS_SIMDIR/submodules/SPRINT_OSI_S_NiosII_cpu_ociram_default_contents.dat ./
  file copy -force $QSYS_SIMDIR/submodules/SPRINT_OSI_S_NiosII_cpu_ociram_default_contents.hex ./
  file copy -force $QSYS_SIMDIR/submodules/SPRINT_OSI_S_NiosII_cpu_ociram_default_contents.mif ./
  file copy -force $QSYS_SIMDIR/submodules/SPRINT_OSI_S_NiosII_cpu_rf_ram_a.dat ./
  file copy -force $QSYS_SIMDIR/submodules/SPRINT_OSI_S_NiosII_cpu_rf_ram_a.hex ./
  file copy -force $QSYS_SIMDIR/submodules/SPRINT_OSI_S_NiosII_cpu_rf_ram_a.mif ./
  file copy -force $QSYS_SIMDIR/submodules/SPRINT_OSI_S_NiosII_cpu_rf_ram_b.dat ./
  file copy -force $QSYS_SIMDIR/submodules/SPRINT_OSI_S_NiosII_cpu_rf_ram_b.hex ./
  file copy -force $QSYS_SIMDIR/submodules/SPRINT_OSI_S_NiosII_cpu_rf_ram_b.mif ./
}

How do I make VUnit copy all these files to the simulator local directory? I have not yet found any function that can be used to do this in its Python interface!
https://vunit.github.io/py/vunit.html


texts: Is using passive anti-aliasing filter with its transfer function instead of an active filter common or reliable?

texts:
I need to ask this general question with an example for clarity.
Imagine I have to measure a signal with BW of 5kHz and I need to make a unity gain active anti-aliasing filter with a steep roll off where the stop band is required to be -60dB at 10kHz and for the max frequency I want to set the 0.1dB point at 5kHz.

What if instead I make a simple RC filter and set the stop-band again to -60dB at 10kHz. Obviously in this case the 0.1dB point will shift to a much smaller than 5kHz.

But can this be fixed later programmatically if we know the transfer function of RC filter? So is this idea of using a much lower cut-off RC filter and reconstructing the signal back by the transfer function practical or used? (I'm asking because if there is no problem I would use the simple RC AA filter and later apply inverse transfer function instead of building a 10th order active filter which could be more tedious)


texts: Balanced impedance CM and DM stages EMI Filtering

texts:
Here is the following assertion :

I would like to understand why line impedance imbalance can cause CM noise to get converted into DM noise ?

Thank you very much !


texts: Building a battery pack, how do I recharge it with USB?

texts:
I am working on a small 12V boombox project and trying to figure out how I should approach the power supply. I have some goals that I want to achieve:

Should be able to be charged with an iPhone charger (USB)
Should be able to play while being charged.
As light as possible
Small footprint

At the moment I'm thinking of making a battery pack using 10 Eneloop batteries. To me this seems to be the lightest and most easily configurable setup for a small boombox, but if you have other ideas, I'm open to that.

But what do I need to set it all up and what do I need for the charger part?
The batteries will be built into the box so charging and playing must be able to happen without any interaction with the batteries. How long do you think it will take to charge the pack? I'm a beginner so ideally every step should be explained.


texts: I am working on a powerboard that may need to switch up to 2kA and while working on some simulations the question occurred to me.  How much current can flow in/out of a ceramic smd capacitor when constrained to a very small time frame?  For example; the capacitor is 10uF and 100V and the pulse is 0.1-1us, which equates to a frequency of 1-10MHz, and in the datasheet for the capacitor this gives an ESR and characteristic impedance of about 0.01 Ohms.  Staying within the 100V rating, this gives a peak current of up to 10kA.  Will capacitors actually allow current at that level, even for such a short duration, or is there some other factor that comes into play?


texts: Is there any way to obtain linear or angular distance proportional to a voltage signal?

texts:
If we have a programmable arbitrary function generator as a voltage signal source and if we are able to output any waveform like a sine or exponential decay as output voltage versus time; how can this voltage be translated to a linear motion or angular motion?

I think as an example for this type of a voltage to motion translation a seismograph:

So basically if we have a voltage varying between -1V to +1V and if we want to translate it to a linear position between -10cm to +10cm or a angular position how is that possible? I know that servo motors are using PWM signals but in my case I would like to know if there are motors or interfaces which translate analog voltage to position.

So if the voltage output we generate is a sine I want the motion to be a sine, and if it is a decaying sine I want the motion to be a decaying sine. If the voltage is zero the motion is at its reference point like the needle above and if the voltage at a time is 0.5V the position at that time will be at +0.5cm ect. But this response must be quick enough to mimic the voltage waveform. I'm talking about not more than 100Hz. Is that even possible?


texts:
I'm wondering why LED indicators are not used on patch panels and on keystone jacks.
I already know that usual LED signals are derived from a 16 bits pulsetrain used in the auto-negotiation mechanism of 802.3
Two questions:

is there a simple circuit (or simple integrated circuit) used to decode that pulsetrain?
if there is no local power (as is the case with a patch panel), is there a way to get that power from the remote equipment (remote end of each of the 2 connected cables)?


texts: Raspberry Pi power switch preventing gnd from HDMI

texts:
I got a problem with my Raspberry Pi setup.

I'm currently using an arduino to control an IRL520N to switch GND on and off on the rasperry and that works great, or it did...

My setup also includes an LCD screen with VGA input. The screen is powered with 12v.
The PSU is an laptop brick, 20v and from there I've used two buck converters to bring it down to 5v and 12v.

The 5v goes to the arduino and Raspberry and the 12v to the screen.

I was using an powered hdmi to vga adapter for the screen and it worked for a couple of weeks until it started to get really hot and broke.
So I replaced it with another one and thats when the problem started.

So now when I'm trying to turn the raspberry off (switching the GND of with the mosfet) it's still on. The red light is glowing.

I've traced it all down to the vga adapter and it seems like the ground from the adapter is making a full circuit so the raspberry stays on.

And now I dont really know what the best aproach would be to fix this problem.
I would rather not have to reprogram the arduino but maybe I could fit another mosfet so switch off the +5 aswell?
Or if I can isolate the 12v gnd somehow.

Any suggestions would be appriciated!

Thanks in advance


texts: Programming a Microcontroller - JTAG and SWD

texts:
I have this Microcontroller - S32K118 64 pins.
I want to load my software datafile into the microcontroller using the debugger mentioned below.
I am using this J-LINK Segger BASE debugger model to program my microcontroller.
I have a Windows OS and the software datafile which I'd like to download to the microcontroller has an extension - ".s28"
I have the JTAG Interface Lines on my PCB which is connected to the microcontroller. And I have connected the JTAG Lines from the debugger to the PCB. There is no mismatch like TDI to TDO (like in UART protocol). I have connected like TDI line on debugger to TDI Line on PCB. Like that for all JTAG Connections.
(P.S. Actually, I have 2 Microcontrollers on the PCB. But they are not daisy chained. Each Microcontroller has separate set of JTAG Interface lines)
Please bear with my below questions as I am not that well versed in Software.
My questions :

The Debugger also has the option to program the microcontroller using the SWD Interface. I read the manual which says that this debugger can also use the SWD interface using just the TMS and TCK lines.

But how is the JTAG or the SWD interface to program the microcontroller selected? Will this selection of the programming interface will be mentioned on the software code or should the hardware person select it? If the hardware person has to select it, then how should he do it?
Basic question - How is the programming interface determined between JTAG and SWD? Is it mentioned in the software code or how is it?

In the J-Link Segger Debugger Manual, on page 279, chapter 13.3.3 Menu Structure, it is given as

it is mentioned as the software data file should be .hex, .mot,.srec or .bin format.
But my software datafile extension is .s28
So, will the debugger accept this file? Upon a simple google search, I found that the .s28 and .srec files are Motorola S-record is a file format, created by Motorola, that conveys binary information as hex values in ASCII text form. This file format may also be known as SRECORD, SREC, S19, S28, S37.
It mentions that .srec and .s28 are the same?
So, I can load this .s28 file onto the Microcontroller with this debugger?
I received 2 types of errors as shown below
Error 1 :

In the above image, you can see that I have selected my correct microcontroller part number and selected the required software data file (don't know whether this extension .s28 will be supported by the microcontroller). But I got the error like, COULD NOT CONNECT TO TARGET.
Why is this error coming? I checked the hardware connection, it is perfect.
I tried to change the Interface from SWD to JTAG (as highlighted in the above image. But I didn't change the speed. Both were at 4000kHz). Still, same result I got. No change
Error 2 : After sometime, In the same window, I started getting the error like - "ERROR : Could not download the file"
I didn't do any change in my hardware setup or anything at all. But the error was different.
I researched on the debugger manual, I couldn't find any solution for these errors.
I also also in the Segger forums and the NXP community forums. But still no results.
Can someone please help me with these errors and how to resolve them?
Question 3 :
Suppose the debugger programs the microcontroller. At the moment or the instant while the debugger is loading the software datafile on the microcontroller, what should be the voltage level on the RESET pin? Should the RESET be high or Should the RESET be low? And if it should be LOW, does the Debugger Pull-down the RESET?
EDIT :
Schematic :
Microcontroller - S32K118 64 Pin.
The reset signal on the base of the transistor shown below is on Always high state. So, it will not be a problem. For the JTAG Reset connection, I have taken the RESET signal from the C0103 Capacitor top end.


texts: Cannot move imported LTspice components in Eagle schematic

texts:
I have just started to learn using schematics in Eagle. I have a circuit in LTspice and since Eagle has an import facility for LTspice, I could open my LTspice circuit in Eagle schematic. So far so good, but unfortunately Im unable to move the components which are imported from LTspice schematics in Eagle. I can only move wires or groups. It is really annoying.

Below is an example, I can move 1N4004 because it is not a LTspice imported component but the rest I cant move which are imported from LTspice:

Does anybody experience the same issue? Or is there a solution to this?

edit: I think I needed to left click on plus sign. But is there a way to move only the component in Eagle? In LTspice there is two options drag and move where you can only move the component without the wires.

Is that possible to do in Eagle schematic as well?


texts: Why don't we have more registers in microprocessors?

texts:
Registers are theoretically not required; all microprocessors would still work without registers. But this seemingly trivial addition has helped make microprocessors more efficient.

Why can't we have more registers to further extract benefit from them? They are just memory on chip and one can imagine not very difficult to add? What factor influenced the number of registers to be what they are now and not, say 10x more?


texts: Can't seem to send more than 3 bytes from the NRF24L01+ TX to RX module

texts:
So I'm sending multiple payloads of the same width from the transmitter to a receiver and I see it sends only sends 3 times after which TX_FULL bit is set in the status register, and the receiver gets 3 payloads.
Note I'm using IRQ on the TX side and no IRQ on the RX side (just polling). Also, I'm not using auto-ack.

What I don't get is how come TX fifo getting full at 3 bytes considering the tx fifo size is 32 bytes. I also checked OBSERVE_TX register and I see no lost bytes. Is this the reason behind not receiving more than 3 bytes?

Note that I checked TX_FULL in the status register as it reads 0x0f while pushing to FIFO but as soon as I enable CE bit, I see the value reads 0x2E indicating TX_DS is set, and IRQ is triggered.

From what I have understood from the reference manual, you continue writing to the TX fifo but the transmission only begins after you enable the chip enable (CE) bit and after you enable CE, the data is sent in first-in-first-out order as opposed to sending each byte right away as it gets stored into the FIFO?

Following is what I did to transmit the payload: (for now I am polling despite using IRQ but eventually i'd be using callback functions to service the interrupt)
void send_payload(NRF *nrf, uint8_t *data, int len) {
    power_up();

    for (int i=0; i<len; i++) {
        send_command(nrf, CMD_W_PAYLOAD, data[i], len); // populate the TX fifo with data
    }

    // enable transmission
    enable_chip_select();

    // wait till IRQ handler is done servicing
    while(nrf->state == NRF_TX_BUSY);

    disable_chip_select();

}

For reference


texts:
I've built a signal generator (with an Arduino) what can output 18kHz and 19kHz signals (separately) and it's connected to a speaker. This works just fine, there are no signals on awkward frequencies.

After I've added an LM386 audio amplifier with the circuit (amplifier with gain = 20). Weird frequencies start to show up around 9-10kHz and my 18-19kHz signals are weakened.

Why is that?


texts:
I have this chip on a breadboard that i want to buy, in order to populate PCBs with it.
I searched and searched the internet with the text that it has on the upper part of it, but no matter how much i searched, i could not find the part.
I took some pictures, in case someone recognizes the IC.

I took two pictures, since it was hard to focus or achieve perfect lighting.
The text on top of the ICs writes "CU251 78M AN9N G4".
This is a MUX/DEMUX IC.


texts: How to identify phases of BLDC motor without rotating?

texts:
I picked up a Wye-wound brushless DC motor with three leads, three wires coming out of it via a flex PCB.  Unfortunately, this flex PCB has no color indication.  How can I figure out which lead is phase A, phase B, and phase C without moving the motor?

The motor is in an enclosure that heavily limits its range of motion.


texts:
I need to send video data over a fiber optic cable. The video input is coming via an HDMI link. The fiber optic link is already carrying some other data (an FPGA is controlling the link), so the video will have to be time-division multiplexed with other data on the same link.

Any ideas on how to implement such a system? I am leaning towards choosing an HDMI decoder IC, convert the video data to something like YCbCr 4:2:2 and feeding this stream to the FPGA, which will then package the data and send it over a fiber link. However, I am not quite sure about the following:

How to send and then resynchronize audio over the same link.
How to make DDC and EDID work
How to make hot-plug functionality work.


texts: How can I calculate the base current of a transistor to get a specific emitter-collector voltage?

texts:
For this circuit I am asked to calculate how much base current I need to supply to the transistor to get a Vce = 220.745 mV. The thing that has me stuck in this is that the problem does not provide me with a (betha) value.

Is there a way to calculate the base current without (betha)?

If not I will use (betha) as 100, since the problem tells me to use a Vce I calculated in a previous problem using (betha forward) as 100 and (betha reverse) as 0.01. As you can see I already calculated the collector current (Ic) using KVL. Since the collector-emitter saturation voltage is approximately 0.2 V, I assume that my transistor is in saturation.

When the transistor is in saturation, does Ic = (betha)(Ib) still apply?

I would really thank your reply :)


texts:
I've made a circuit based on the schematics below, which works fine at simulation. The goal is to add some extra oomph on the output of a LT1210 opa (V1) to drive a piezo element at higher voltages with square wave. V2 is a lab PSU with 300uF AE and 2uF cer-cap between GND and V+ (not drawn in schematic).

Since I'm driving the fet's in deep saturation the spec shouldn't have any influence as far as I can tell. Gate charges is below 20nC for both.

I get the same gate voltages as in simulation when reading the scope, but the output voltage is around 10 times lower than input.

Any thoughts? I suspect the answer to be fairly obvious..


texts:
I'm currently designing a simple PCB that uses a MAX3221 to send/receive RS232 over an ethernet cable along with an optional 1-wire thermocouple reading (The thermocouple breakout can be soldered in depending on a users needs).

Note: I forgot to add the Cap values to the diagram but they are all 0.1 μF

The end device i'm targeting has 4 lines that i'm trying to tap into (24 VDC, GND, Tx, Rx). My idea was to push the 24 V through a LDO and use that to provide a source of 3.3V to the parts where it's needed (E.g. MAX 3221 & Thermocouple breakout). What i'm finding though is that the LDO I'm using (LM1086 3.3V) is getting incredibly hot. My continuity checker doesn't show a connection between output and GND when unplugged, but the moment I plug the device in it bridges.

The system works fine when sourcing a 3.3 V line from elsewhere (E.g. cheating it from the raspberry pi I have attached on the other side of a different transceiver).
Strangely, I have managed to solder up a couple of PCB's with an LM1086 & BA033CC0T with bent pins that are working.

Is there an issue in my circuit design? I have a feeling that I'm fundamentally missing something with the LDO that's causing this issue.
Or could it simply be a matter of faulty parts or poor soldering on my behalf?


texts:
My house is on a giant hill. The city only provides enough water pressure to get me water half way up the hill. A long time ago a pump was installed in a small dugout on the side of the hill (about 1000 yards from my house).

The pump is controlled to pump water only when we require it at the house. There is a buried 220 Volt electrical line running from the house to the pump. SO in the winter, when the pump is not active it freezes. I have recently installed a climate control system run off propane to warm the dugout when I need to.

I would like to have a remote temperature reading for the dugout sent to my cellphone or somewhere I can access via my cellphone. Its too far for wifi and Bluetooth and the only thing I can think of is an AT&T air card plugged into a microcontroller.

Anyone have any better solutions?


texts:
I just bought a wifi module shield and using it with Arduino. I power Arduino (with the wifi shield on it) via USB from the PC. I need to demonstrate it without using the PC as a power supply. And I cannot also use 2.1 power plug or 9V adapter jack since i don't have that component. I don't have time even to buy that.

So the only option for me is to use the Vin pin with a 9V battery. I am just afraid if i may damage the wifi shield or Arduino. I read some warnrnings about that.

Is the Vin pin used only with Arduino without a shield on it?

Thanks in advance,


texts: Circuit for OpAmp-MOSFET based constant current source for 0.2 - 1.5A

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I'm a beginner in electronic circuit design and have designed my first Voltage based constant current source using OpAmp driven MOSFET (based on this).

The intended current output needs to be between 0.2-1.5A.
I have simulated the circuit and got the following outputs:

I(D3): current through the LED

V(n004): Voltage at MOSFET Source pin

V(n009): Voltage at MOSFET Drain pin

V(n001): LED driving Voltage source (V1)

The simulation does not show any oscillation and shows good linear current control by V2 (simulated for Voltage range of 0-5V).

I just wanted to know if this circuit would indeed work as intended? Its difficult to order parts again during this time, so I seek the help of the experts.

Thanks,
CM

Datasheets:

LM324

BUK6D230-80E

SFH4770S

Simulation software: LTspice


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I've just bought new 30W soldering iron and now that I'm home, I've tried to desolder few capacitors from my MBO. Anyway, I've turned the soldering iron on, waited few minutes for it to heat up and then put the tip to the part I wanted to desolder. I was amazed - nothing happened !! Well, after let's say 30 seconds (I know, that's too long but I didn't get anything e.g. smoke or something and the capacitor didn't heat up because I was holding it on the other side) I've managed to somehow desolder it ... But now I have solder in holes, and I thought well, that's no problem.

I've used this technique:

but unfortunately, this doesn't work. I can't melt remaining solder (in the holes) by applying tip of soldering iron to the one leg of capacitor. Actually, I don't think that I can do anything with this soldering iron ...

Is there something wrong with it or with how I am using it ?

Thanks !


texts: What is the purpose of this coil in a medical defibrillator?

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Please can someone explain the function of L coil in this circuit? This schematic is just medical defibrillator, but almost every capacitor discharge circuit has some series coil.
Is it some kind current limiter?


texts: Best way to convert 5V DC to 110V AC at 50Hz for pdlc film drawing 2mA max. Size is the thing!

texts:
I'm working on a project in which I'm hoping to integrate several small segments of pdlc film, which starts off diffuse white/'frosted', turns clear when excited with 110V AC at 50Hz and is apparently dimmable although I haven't tried that yet. This is the closest thing I have to a datasheet:

I want to power 6 segments of film from a 1s lipo cell, which is already boosted to 5vdc for other parts of the project.  In total I will be using 13sq.cm at most so they won't draw more than 1.5mA. I also need to figure out how to control the degree of transparency of each segment independently, preferably using PWM signals from an arduino.

Size is critical as everything needs to fit inside a handheld toy and it is already crowded!

Would it be feasible to create an AC signal using arduino PWM output and boost that to the required voltage?

All of the solutions I can find off-the-shelf for boosting the voltage are just too big for my project but also provide way more power than I need. Most of their bulk is transformer and heatsink. Is their a way to get the voltage gain at 50Hz without a (relatively speaking) bulky transformer? All of the smallest transformers I can find have a minimum frequency way above 50Hz.


texts: Why exactly does Connecting a Motor Directly to an Arduino Damage it?

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I understand that you usually need an H-Bridge or some sort of Motor Driver to connect a Motor to an Arduino, as otherwise it will damage it.

But why is this, I mean I realize each pin can only handle 40amp, but is it dangerous because the Arduino cannot supply this much....or is there some kind of "blowback" voltage this can damage it?


texts: What's the Common and the NO in this diagram

texts: I think the browns the common wire and the black is the normally open am I correct?


texts: Is it safe to keep using graphics card with blown diode?

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Is it safe to use my GTX 1070 ti with a blown diode? It works as usual. Please see attached image. I don't know much about this, but it looks like d33 has blown.
Thanks in advance.


texts: Short range - low bitrate data transmission under water

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I am looking to get a hold of small transmitters for use under water (sea water). They will be rigged to my sensor equipment and attached to fish for scientific monitoring, so size is very important.

The transmitters will need to:

Transmit digital data packages of around 256 bits once per second.
Have a minimum range of approx. 150 meters for good measure.
Be able to work in an system with 10 or more active transmitters at the same time.
Be as small as possible.
Be as energy efficient as possible

My research indicates that my best bet is to build fixed frequency am-transmitters. (Availability, cost, size etc.) with small crystal oscillators. Is this a viable plan or are there better solutions out there?

Also, does anyone know if a setup like this could work under water? Keep in mind that I only need a range of 150 meters.

Since I only need a bitrate of about 512 bits / second per transmitter (I want overhead for more data), would a lower frequency transmitter give me lower power consumption?

There are no size or power restrictions on the receivers.

EDIT:
I am getting a lot of good information. The attenuation in sea water is much higher than I had expected, thanks for the graph.

I see that even my initial plan, using frequencies in the LF-band is out of reach at this range.

1KHz at 20 meters range with more receivers placed seems more realistic, but even this does not look very promising. It seems that EM transmission just isn't that feasible under sea water. Maybe I'll be better off with an acoustic transmitter or some form of passive telemetry.

Thank you all.