texts: Is CPU/GPGPU heat dissipation quadratic in clock frequency?

texts:
In the following article on overclocking a Pentium from 1GHz to 5GHz using liquid nitrogen: The 5GHz Project, there is an assertion that "Heat dissipation rises exponentially during extreme overclocking".  However, in this post on CPU power heat:  How are the CPU power and temperature caculated/estimated?, it appears that work is linearly proportional to frequency, as follows:

  To work out the work done whenever the gate changes state you can model it as a capacitor with some effective capacitance, \$C_g\$, and you get:

$$W = \frac{1}{2}C_gV^2$$

  and the power is the work per state change times the number of state changes per second, so:

$$P_g \propto C_gV^2f$$

  If you add up all the logic gates in the processor you can define an effective total capacitance, \$C\$, that will be the sum of all the gate capacitances, \$C_g\$, so:

$$P \propto CV^2f$$

The 5GHz project page then states "In the past we recorded about 135 watts using the Chip-con compressor at 4.1 GHz. Using our nitrogen cooling to break the 5 GHz sound barrier would produce peak heat dissipation of up to 180 watts emitted from a die surface area of 1.12 square centimeters. Applied to our example that means 1.6 MW per square meter."

I asked the above question in the context of the question How are the CPU power and temperature caculated/estimated?.  My follow-on question was deleted but I got this reply before it was deleted:

  The formula only suggests a linear increase with respect to frequency if the voltage is held constant, which is not going to be true for large overclocks such as this one. The CPU becomes unstable at high frequencies, which can be partially compensated for by increasing the voltage. Thus, for large overclocks, the power grows faster than linearly because of this accompanying voltage contribution. I don't think it's literally exponential, however; that may be just imprecise language. The details would probably be better left to another SE site.

Probably the 5GHz people meant to say "increases quadratically", assuming that as they increase frequency, voltage is also increased proportionally to level necessary for chip to function reliably.   What is the equation relating frequency and required voltage level for a chip which operates stably at frequency F and voltage V?  Note that for GPU such as AMD HD7850, I can set the clock frequency without changing the voltage supplied to the chip, so it is not automatically the case that changing the frequency implies a change in supplied chip voltage.  Clearly at some point my chip will stop functioning properly, so it would be helpful to have an equation showing how much to increase voltage as a function of frequency.  Also note that some GPU users undervolt the chip, why would they do this?

Under the assumption of quadratic heat rise in frequency/voltage, it would be more efficient to have 5 processors running 1GHz rather than 1 processor running at 5GHz, is this correct?  I.e. space is quadratically cheaper than time, is that more or less correct?  How to correctly state this tradeoff?

In this response to a question on How Modern Overclocking Works, @Turbo J says

  You can increase the clock frequency further when the voltage is higher - but at the price of massive additional generated heat. And the silicon will "wear out" faster, as bad things like Electromigration will increase too.

So again, the question is what is the equation that models "massive additional heat", is "massive" quadratic, i.e. are we still talking about the work equation above?


texts:
I am designing a boost converter. I know maybe the specs I want would suit better in another topology like Half-Bridge or Full-Bridge but the boost topology is simpler and inductor winding is simpler too I think.

My boost converter should be:

14V input voltage
15 to 30V output voltage
10A output current so the output power will be 30*10 = 300W
300KHz switching frequency

I am using this application note from Texas Instruments and I am getting this results:

Inductor value: 2.5uH
Max switch current: 45A

Is it possible inductor has such a low value? Is the peak current really that high? I am planning to use an IRFZ44 MOSFET that specifies a Pulsed Drain Current of 200A, is that the parameter I have to look at or should I calculate Irms and look at Continuous Drain Current?

Also I was looking at this core but the Al value is so big I doesn't event need a turn around the core to get 2.5uH! So I can't use this core?

Also I would like to know how to calculate the inductor to ensure I am not exceeding the Maximum Flux Density. I have a book called Power Supply Cookbook but it seems to focus more on Half-Bridge and Full-Bridge inductor design than Boost design.

I am not an expert so there are a lot of things I don't know any guidance, book, links would be really appreciated! Thanks!


texts: Why do comparators generally have higher offset voltages than opamps?

texts:
I need to compare a signal to a constant voltage; the signal ranges from 0 to 30mV, and I require a response time of 50ns at 250µV difference. The signal is a triangle wave with a slew rate in the range of a few mV/µs.

When having a look at the comparators offered by TI, they start at an offset voltage of 750µV, with 10ns comparators starting at 3000µV.

When, however, looking at the list of opamps, those start at 1µV offset voltage, with 100MHz amplifiers starting at 100µV.

It's strongly encouraged to use comparators, not op-amps, for comparing signals, so the only option I'm seeing is to pre-amplify my signal with a precision, high-speed op-amp, then use a comparator. However, this sounds wrong. If this is possible, then why don't chip makers offer this as a monolithic solution?


texts: Capacitor for triggering negative edge J-K Flip Flop's Clock

texts:
I have some SN74LS73AN Flip-Flops which, if I understanding well, are triggered by the negative (falling) edge signal of a clock.
I wish to use a simple pushbutton as a clock, and I am aware that, for a clean (debounced) clock signal, a capacitor is needed.
I'm using a 5v DC powered breadboard and a SN74LS73AN J-F Flip Flop.
What kind of capacitor should I get?
Thank you.


texts: Detecting whether the card is present or not in a smart card reader

texts: Recently I bought a 32320 Smart Card Reader. I had no trouble making the circuit, but I could not figure out what command to use to tell if the card is in or not. Any ideas?


texts:
I would like to plot the power obtained by this simple recovery circuit (UR1eff^2/R1) according to the value of the resistance R1. But as it is a sinusoidal function, it takes the average value of the voltage i.e. 0. How to plot the power according to the resistance in this case?
Thank you very much for your help.

Well the measurement doesn’t work. Here is the result:


texts:
[ From Marcel Pelgrom's Analog-to-Digital Conversion ,pg34]

I was reading this example from the noise sampling section and I am bit confused. Why does he say that the noise contributions from each capacitor will cancel?

My understanding is as follows:

In the first configuration, the signal Vin is sampled on both capacitors and the thermal noise is based on the parallel equivalent capacitance of $$C1+C2$$. Thus the noise is $$kT/(C1+C2) = kT/(2C1)$$. Thus, the total SNR is $$(2C1Vin)/kT$$
After the capacitors are reoriented in a series configuration, we can combine the two series capacitors to have an equivalent capacitance of $$C1/2$$. The total signal voltage also doubles to 2Vin. Thus, the total noise on this new configuration is $$kT/(C1/2) = 2kT/C1$$. Thus, the new SNR is $$2C1Vin/2kT = C1Vin/kT$$

Thus, the SNR is halved in this new confgiuration? I don't understand how he is saying that they cancel eachother?

Do I have to account for the thermal noise caused by the first sampling moment when analysing the second configuration?


texts: Conversion of PID controller components with state feedback into single transfer function and discrete state-space form

texts:
I've been wrestling with this problem for about a week now, as a part of a year-long project. We're designing a controller for a specific reactor based on a model. After looking at this for a while, I still can't get this to work - so I would really appreciate it if I can get some help.

One of the published literature reviews that we've based heavily upon lists a PID controller into each separate components instead of a combined equation, like so:

$$
\begin{cases} P(n)=K_p[G(n)-target] \\I(n)=I(n-1)+\frac{K_p}{T_I}[G(n)-target]\\D(n)=K_pT_D\frac{dG}{dt}(n)\end{cases}
$$

Simply combining the three components into the PID controller output:
$$
PID(n)=P(n)+I(n)+D(n)
$$

And from here, the author adds an additional layer of state feedback on top of the PID signal to get the final controller output applied on the system.

$$
\begin{cases} Q(n)=K_0R(n-1)+K_1Q(n-1)-K_2Q(n-2)\\R(n)=(1+\gamma)PID(n)-\gamma Q(n-1)\end{cases}
$$

And R is the final "controller output." Here, the \$K_p\$ is the process gain, \$T_I\$ and \$T_D\$ are the integral and derivative gains, \$K_0, K_1\$ and \$K_2\$ are "gains" tuned for the state-feedback (immutable), and \$\gamma\$ is a constant, 0.5. \$G(n)\$ is the system state, \$Q(n)\$ is an estimated state that affects the model dynamics, and \$R(n)\$ is the actual final output that is sent to the plant.

I was trying to first convert the whole thing to a single controller transfer function, but I was told that simply adding them together won't work.

I was also tasked with finding a discrete state space representation of this controller. For this, I tried to change the \$\frac{dG}{dt}(n)\$ into \$G(n)-G(n-1)\$ to get rid of that issue.

Next, I tried to define a new state variable for the \$Q(n)\$ so that the \$Q(n-1)\$ and \$Q(n-2)\$ could be converted into first order.

I then tried to substitute the values into the PID controller, to get the \$G(n)\$ as the state variable. These efforts were all based on recommendations by my professor.

However, I'm still very much stuck, as I've been blindly following his directions without an overall vision to works on it. I thought it would be a simple matter of Tustin transformation - oh, how I was very wrong...

I'm quite frustrated, as after a week-long effort, I'm still stumped by what appears to be a simple problem.

If possible, may I humbly ask for your help on these two specific questions?

Convert this controller into a single controller transfer function (as typically seen in any transfer function representation, i.e. \$G(s)=\frac{1}{s+1}\$)
Convert this controller into a discrete state space representation, leaving the sampling rate as a variable?


texts:
A close examination on magnet wire tables of various manufacturers like `http://www.epicos.com/EPCompanyProfileWeb/Content/CABLES/Magnet%20Wire%20Data%20Sheet.pdf  (page 9),shows that the ratio of the conductor area and insulation area it is not remains the same throughout  the sizes of wires. Insulation building in thinner conductors, occupies  more area compare with thicker one. For example the insulation of AWG #14 is 4% of the total diameter and 12% in AWG #30 (the second image it is exaggerated to show the impact).

`

The first question is: why there is not a constant ratio of the insulation area to the total area in all AWG conductors?

The second question is: can we take the advantage of the surface increase due to the insulation in thinner conductors and to design for more current capacity than thicker conductors?


texts:
What is actually going on in waveguide when the wave is passing through it ?
If I am not mistaking , the plane waves are "fed" to the waveguide and there is a cutoff freq above which the waves can pass.
Now I want to visualise the whole picture. As far as I know , the plane waves have flux densities having sinusoidal variations. How these variations are related to modes in waveguide ?
I am not able to fully understand the modes in waveguide..Plz help me out on this.
Thanks in advance.


texts: Why does a slightly out of specs power supply works and what are the possible consequences?

texts:
I have the following lamp:

Its power supply is rated at 5.6V and 2.68A blew up some time ago.
I then went to an electronics shop where I've been suggested that I could replace it by a universal power supply for laptop.
I did and it worked well for years but then the universal power supply, which was rated at 5V and 4A finally blew up as well.
Now I have at hand an USB power supply like the following, it can supply 5V and up to 2.4A:

As I heard that some appliances can deal with a slightly out of spec voltage, I decided to give it a try and it worked.
Luckily, the USB power supply manual says that if it's asked to deliver more amps that it can actually do, it will shut itself down.
So I suppose it's "okay" but well ... I don't really have any electrical knowledge to support my theory!
Question, two-folded:

why does a slightly out of specs power supply works in this case?

and can one assume it is safe to use it or is it strongly discouraged?

(as you might have guessed, the product ran out of production so I can no longer get a replacement power supply for it)
Edit:
The lamp is a Philips Living Colors (1st gen. from 2008), it is rated at 15W, the 5.6V/2.68A power supply plugs on 220V and the lamp is not chargeable.
Pretty difficult to find much more information than that even though it's relatively recent.
FWIW, there is some stuff about its internals in this link.


texts: Power consumption when DC motor runs on battery

texts:
I have small doubt about power supply selection for a running motor. I have a small dc motor, which is rated for 12V , 3A(rated ). When the motor runs with a load 4000N, the current consumption is 1.5A.

So I have to choose a 12V, 3A = 12 * 3= 36W power supply to run the motor.This is because DC power supply can supply continous 3A current without any disturbance.

Now I wanted to run same motor on battery. I would like to know how much power should be supplied by the battery to run the motor theoretically.

When motor runs on battery, it takes full current from the battery; as per formula (\$e= l \frac{di}{dt}\$).
 It said that current required by motor = 3 \$\times\$ current required while running on starting.

When we run the motor on battery eventually battery voltage got dropped, taking more current.

I would like to know what is the percentage of current it takes.

If we consider above system 12V, 75Ah battery is it efficient?

Can someone explain with proper calculation here?

While running on battery;
motor will turn on every 5 minutes and after that it will be turned off. The motor is made to run 11 hours on daily basis.


texts:
In the attached image, without C1 & C2 (used only as de-cap) mounted, when 24V is given at TP1 and nMOS (Q1) is turned ON, the circuit works fine and I get 24 V at TP3.

But when C1 & C2 are mounted and as soon as 24V is given at TP1 and nMOS (Q1) is turned ON, the pMOS goes bad and there is short-circuit between source & drain.
The capacitors C1 & C2 are good as I checked them.

Can anybody expalin what coud be the reason? Is it because of sudden inrush voltage from the charged capacitors C1 & C2?


texts:
I'm trying to wire up an ADS1115 Analog to Digital Converter so I can use it with my FPGA  Nandland Go Board.
Can anyone confirm if this is the correct wiring?
I think I've set it up so that I can read in the voltage of the potentiometer on A0 (through the LED, to see it working)
I'm concerned that I've connected the unused A1, A2, A3 to ground, and left Alert hanging...is that ok?
The pull up resistors (4.7k) are both connected to SCL & SDA lines

Thank you


texts: Cap in Series with a DAC Reverse Current

texts:
I'm using a 8-bit DAC: (DAC5311IDCKR) to generate a 1.5V Amplitude sine wave with a 3.5VDC offset. I've put high-pass RC filter across it shown below to block DC so that it becomes AC.

I understand that the capacitor will act like a voltage source, and my SPICE simulator tells me that the cap's voltage becomes greater the source and (ideally) pass current back into the DAC. I'm concerned that this will either, damage the chip or not work at all because the chip doesn't allow currents in reverse.

Is my concern valid?
If so, when choosing a DAC what features should I look for on datasheets that tells me I can drive a load like this?


texts: What is the plastic keying filler called for IDC/Dupont connectors?

texts:
Some male IDC and Dupont connectors have a pin missing, with the corresponding female connector having that hole blocked up with some plastic, so that the cable can only be mated one way.

I can however only see for sale female IDC and Dupont connectors that have all their holes unblocked.

I am having no luck figuring out how you are supposed to block off the keying holes yourself.  Is there a particular plastic piece you insert to achieve this, or is it just a matter of cramming the hole with whatever you can find and perhaps melting it in place?

The professional ones look either moulded or as if a plastic pin has been pushed into the hole which would be a nice touch, but I have no idea what this plastic pin may be called and all my guesses (key, block, filler, etc.) are coming up blank.

Is it possible to buy these keying pieces for both IDC and Dupont connectors, and if so what are they called?

Here is an example pic from Google showing a keying pin on a Dupont connector:

And another showing a blue keying pin on an IDC connector:


texts: Battery hull/foil damaged while changing display of a smartphone

texts:
The silver foil of my smarthphone's battery got damaged while I exchanged the touchscreen:

The battery was glued to the body of the phone and I didn't manage to remove it without damage to the foil.
Now I have two questions:
1) What is the purpose of the foil? Is it there only for protection of the other parts of the battery or is it a vital part of the battery?
2) Can the battery still be used or does it have to be replaced?


texts: Why does DC motor speed controller turn into on/off switch when source voltage is too high?

texts:
This is a bit of a vague question as I'm not 100% sure what I'm asking so I apologise in advance, I'm just hoping to better understand something I noticed the other day.

In my endless tinkering I recently dismantled a cordless power drill to cannibalise the DV motor, as well as the variable speed control trigger assembly to be used on another project which requires a variable speed motor with good torque. The battery power source for the drill is rated at 18V (measured closer to 19V with a voltmeter) and this works perfectly. However, I would like to wire it up directly to a mains plug so that I can run the motor for long periods of time (on the order of a few hours). I happened to have a mains power supply laying around with a measured output of ~21V (rated 24V). I assumed this was probably "close enough" and hooked up the circuit and what I found surprised me.

Under normal circumstances, if the motor/speed controller are connected to the 19V battery supply that it came with, and I gradually depress the speed controller (which I assume is just a potentiometer?), the speed of the motor gradually increases expected as expected. However, when I connect it up to the 21V supply (also DC) and gradually depress the speed controller just as before, the motor doesn't turn at all until the button is almost completely depressed, then suddenly the motor whirls into life at its maximum speed! So when the source voltage is only 2 volts higher, the potentiometer(?) starts behaving more like an on/off switch.

I was not expecting this. Does anyone have some explanation as to why this would be the case? I was expecting little to no significant difference in behaviour, maybe a slight speed increase due to the higher voltage, but for the speed control to just stop working is strange to me.

To be clear, the speed controller still works fine, it's not broken. If I hook it back up to the 19V supply, everything works as normal.


texts:
I am designing a PCB for a LED, photodetector (several different tried), TIA (OPA380), and linear regulator (LT3042 to reduce noise). It's on FR4 from OSHPark. When the LED is on the photodetector's current is converted by the TIA to a voltage. The TIA has a feedback resistor of 10M because the current is tiny in this application. I noticed the voltage I was getting out in my test was lower than anticipated (maybe 1/10). I checked the feedback resistance of the whole circuit, and found only 500k, so I took it apart. When I checked the resistance of the plane board with my ohm meter, it reads out of range high (good). When I check the resistance of the feedback resistor, it reads 10M (good). When I check the open resistance between the out and inv input of the opamp (not a sound practice, but w/e) it reads high (good). When I put the Opamp on the board, the feedback reads 500K. I scrubbed the board to the best of my abilities, checked all the pins of the opamp are spaced apart correctly (ran a blade between the pins to take out any dust), checked that my board layout is not too far away from the example... To be fair, feedback resistance measured this way isn't really correct, so it could be something else.

So far searches of the internet haven't yielded any advice on what else I should be checking.


texts: How are two definitions of baud rate same?

texts:
The bit rate V baud rate has been a confusing topic for me lately. I feel like I am clear about the difference between these two.
But going through the definitions of baud rate, I find two different definitions in use:

A baud rate is the number of times a signal in a communications channel changes state or varies.
For example, a 2400 baud rate means that the channel can change states up to 2400 times per
second. The term “change state” means that it can change from 0 to 1 or from 1 to 0 up to X (in
this case, 2400) times per second. (This is the definition from my teacher's notes.)

Baud rate as the no. of symbols transmitted per second.
Consider a symbol "A" which is encoded as "0100 0001" in ASCII format. If I send this symbol within 1 second, I have bitrate of 8 bits per second.

For baud rate:
According to first definition, baud rate is 1 baud per second.
But according to second definition, the baud rate is 3 bauds per second since the signal changes its state three times (0 -> 1 -> 00000 -> 1).
So how do these two definitions link together? I can't see any match between these two definitions with "my" level of knowledge. Thank you!!
And how is the calculation done in following image? I understand the calculation for the bit rate but how is baud rate calculated?


texts:
What is a namespace in NAND or NOR based Flash Memory?

Is it a range of addresses of NVM? If yes, then is it specified by SSD Manufacturer?


texts: Does a Vcc layer cause noise to a 4-layer RF PCB?

texts: I'm designing a 4 layer GPS tracker PCB with the 2nd layer as ground and 3rd as Vcc. Is this a good practice? I know a gnd layer is good but I'm not sure how to distribute the positive of the supply on the 3rd layer. Should I cover the whole layer with the supply even underneath the antennas? Or just pour Vcc underneath the Vcc pins?


texts: How to play a microphone out of a speaker?

texts: So I have a small amplifier that plugs into a 12V source and a standard 3.5mm headphone jack and plays pretty good sound to a 8ohm speaker. I am wondering if I can connect the 3.5mm headphone jack to an electret microphone and play the sound from the microphone out of the speaker. I guess I am wondering what kind of voltage the mp3 player outputs. Since that work great with the amp I guess I am wondering how to get an electret microphone to the leverl where I could input it into the same amplifier.


texts: Why is there a 2 in front of some of these passive component parts?


texts: Do these LED's have a constant current driver built in?

texts:
I bought these LED's of eBay and connected them all (5) in parallel with a 4.7Ohm series resistor each.

This should have given me a total current draw of 1.7A. However, when I measured it, I was only getting 0.4A.

I then connected a LED directly (via the multimeter) to the 5V power supply, expecting the LED to blow. However, the LED instead drew 0.7A, as specified in the description. There is no datasheet, and I'm unfamiliar with LED's having a current regulator built in.

So why didn't my LED's blow?

In case the link dies in the future, here are the specs:

Forward Voltage:3.2-3.4V
Forward Current:700MA

enter image description here

Edit: I did the following test measurements. There are some discrepancies I believe which are associated with the quality of the multimeter I am using.

Note: The voltage measurements were done with the 'ammeter' removed.

\$I_{circuit} = 230mA\$
\$V_{supply} = 4.95V\$
\$V_{led} = 3.3V\$
\$V_r = 1.23V\$
Ground pad: Warm

Note: The voltage measurements were done with the 'ammeter' removed.

\$I_{circuit} = 140mA\$
\$V_{supply} = 5.05V\$
\$V_{led} = 3.17V\$
\$V_r = 1.63V\$
Ground pad: Warm

Note: The voltage measurements were done with the 'ammeter' removed.

\$I_{circuit} = 650mA\$
\$V_{supply} = 4.63V\$
\$V_{led} = 4.63V\$
Ground pad: Very hot.

Further note, that the LED when directly connected to the power supply, without the ammeter still does not die (held for 5 seconds).

The LED is soldered onto a PCB like so:


texts: Generally and briefly, are there any direct application of gray code in electronics? If so, what are they?


texts: how to connect strain gauge to HX711 module

texts: I need get strain gauge reading to Arduino. so far i have found load cell Wheatstone configuration circuit here 3rd answer. I need to know if i connect a strain gauge to one +Active resistance, and other 3 resistances left with 350Ohm constant resistors, will this configuration give me strain gauge reading with same connection as given in the circuit?


texts: Adding an LED through a FET circuit that currently drives a solenoid

texts:
I would like to save space on a layout by consolidating a FET or two, where feasible, on an existing board. One of the FETs used, a coolMOS P7 series (IPA60R280P7SXKSA1), seems to have the drain current availability and the acceptable logic to combine its existing solenoid drive function to also include a green LED.

Factoring in the flyback diodes/magnetic field collapse aspect of the solenoid, would it be a poor design practice to put an LED in parallel? If so, why?

Thanks


texts: How to use LED holder when mounting on a case with pcb inside?

texts:
I am making a case with a front and back piece with the PCB mounted on the back piece with LED supposed to be mounted in the holder in the front case piece.
I was planning on soldering the LED to the pcb holes first then trying to squeeze it into the bezel holder while fitting the front case to the back case piece. However that will damage the straight LED leads and damage the LED when I remove the front case in the future as the bezel holders either snap in or screw in.

How are widely sold 5mm LED holders meant to be used and what is the normal way to do what I am trying to achieve?


texts:
Ok this is my first time trying some kind of reverse engineering and I have few experiences in PCB testing so it may be a basic question.

Basically I am trying to get the schematics for an 8 channel output circuit for which I only have the board, with no documentation whatsoever. I have mapped out the VCC and the GND on the input pins by using a ohmmeter to measure resistance between the VCC input of an DAC converter and the input pins. I have mapped the pins for which I get 0 ohms as VCC inputs. I have mapped out the GNDs in a similar manner.

Another thing to know is that the board is not powered up while I am doing these tests. There are no voltages or currents applied anywhere but for the voltmeter I am using.

My question is this:

When I measure resistance between VCC input of the DAC and the pins I have mapped as GNDs, I get 515 ohms of resistance. The same thing happens when I measure resistance between the GND input of the DAC and the VCC pins.

What could this resistance represent? I would have tought that since ground planes and power planes are separate, I would get an overload reading on the ohmmeter?

I am thinking I do not understand power and ground planes correctly.


texts: Can I connect the frame ground on a PSU to the 'ground/earth' on a UK plug?

texts:
I have a PSU which has 'FG' (Frame ground), is this just the ground which I would attach to the ground pin of the UK plug?
Image of the Live, Neutral & FG :
Thanks


texts: Frequency Key Shift technique to superpose the digital communication on top of 4–20 mA signals

texts:
I start working with HART devices and I really try to understand how digital data is transferred trough 4-20ma current loop. I start read this article: https://instrumentationtools.com/hart-communication-tutorial-part-1/ and one paragraph said this: "The HART protocol makes use of the FSK technique to superpose the digital communication on top of 4–20 mA signals. The digital FSK signal is phase continuous and has a 0.5 mA amplitude having two different frequencies, 1200 Hz and 2200 Hz, representing binary 1 and 0, respectively. Since the average DC value of a sine wave over a time period is zero, the FSK signal does not add any DC component on the 4–20 mA analog signal."
I understand that the digital data is superpose on top of 4-20mA, but what I don't understand is if that analog signal "vibrate" to different frequency to produce digital communication data, or is another signal (the "digital" one) beside that, and if it is, how can they don't interact?

Also, in this article: https://instrumentationforum.com/t/highway-addressable-remote-transducer-hart-tutorial/4526 I found this: "As indicated by Figure 12.8, HART provides two simultaneous communication channels: the 4 20 mA analog signals and a digital signal." What are those channels? different voltage? different current? different frequency? And how can they interfere?


texts: Electret microphone signal amplification

texts:
What will be the output of these electret microphones? To be able to have a 3-4 Volts peak output, what should be the gain approximately?

P.S. : Unfortunately these are not products bought from a known seller and there are no part/model numbers etc. on them. I just wanted to know that whether there are a typical output voltage for these kind of microphones or not.


texts: How much voltage will i generate from this DC motor?

texts:
http://www.moog.com/literature/MCG/moc23series.pdf

i am using the C23-L33 model.

if i rotated the motor at the rated speed of 3000RPM, how much voltage will i generate?

can I please know the exact steps of finding the answer out using the datasheet above?

thank you.


texts: How do the Active High and Active Low signal work in Embedded Systems?

texts:
This is about how micro controllers work in general..

The programming that we do is converted into 1's and 0's by the compiler and these machine understandable code are then loaded to the microcontroller..

How does the microcontroller respond to this.. I mean are these 1's and 0's converted into corresponding logic voltage (5v and 0) by DAC? If its like that, how does this small piece of silicon decide what to do with these various combinations of 5v and 0v?

I understand that every single IC is made of logic gates and these gates are composed of transistors.. So how does these transistors respond to various combinations of 5v and 0v?

What makes them look for these logics.. I mean how they monitor these instructions when they are powered on?

So certainly there got to be an Operating System loaded into the mcu that tells it to process and how to process these instructions, isn't?..

Next thing is.. consider a timer.. it is simply a register that increments by one after each clock cycle.. Isn't the OS again that instructs the mcu to increment after each clock? Am I right? In that case, in what language, all the code for a operating system is written?

I can just proceed my work with programming the mcu for different tasks but today I was interested to know how my code is understood by this machine..

Sorry that my question is lengthy to read.. please help me learn these basic things..

Thanks in advance..


texts: MAX3232 overheating/burnt after connecting to PC

texts:
I've got a MAX3232 Serial-to-TTL RS232 board which I am currently using in factory assembly lines. I don't have its picture, but here's a similar product:

This is the circuit I've managed to figure out of the board(I don't have the original schematic):

I'm using the RS-232 board to send streaming data from an electronic Weight scale to PC, where the data is grabbed by my software for display.

The problem right now, is that sometimes the board stops sending data. I used HyperTerminal to check if the weight scale is sending data or not. When it doesn't, I've tried disconnecting and reconnection the serial port connection, unplugging the serial cable and plugging again, turning off the weight scale and even the PC on/off again and such, sometimes with no results. Sometimes the weight scale (WS) stops sending data. When I left if turned off for a while,  and turns it on again, the WS sends data again. I suspect the MAX3232 IC got hot, because I can see the glue I put on the board looking like it's melted off the IC. When it cools down it is operational again.

I've used an oscilloscope to check on burnt ICs - these ones clearly don't have output on pin 14 (refer to schematic), with voltage level nowhere near +- 7V.

I've searched on the internet, and also found other people with issues regarding their IC (well this is actually MAX232) heating up when connecting to PC:

MAX232 overheat problem

MAX232 Overheat

So far I've done some countermeasures:

Replace the burnt/old IC with new MAX3232 ICs from element14. Since the boards were very cheap and made in China the IC were probably of low quality.
Connected the unused CMOS input (pin 10) to GND with 2.2K Ohm resistor.
Added 20 Ohm resistor in series to pin 16 (VCC).

I'm afraid that these measures wont be enough. Maybe I need to isolate my connection. Does anyone have any idea what's going on, and know what to do?


texts: Explain this line of working when solving for the maximum power of a load resistor

texts:
Please, can you explain this line of working from the maximum power transfer theorem:

  For maximum power dissipation in the load, the condition given below must be satisfied
  $$\left. \frac{d^2P(R_L)}{dR^2_L} \right|_{R_L=R_{Th}} = -\frac{V^2_{Th}}{8R_{Th}} < 0$$

It's from this page: Maximum Power Transfer Theorem Assignment Help.


texts: Limiting current draw from a power supply

texts:
I have a power supply that can supply around -60 kV DC and 10 mA. This power supply provides energy to a device known as a fusor. A fusor utilizes a low current and a high voltage to ionize a gas and accelerate the plasma ions toward the center of the vacuum chamber.

However, my issue is that the fusor will pull a very high current (100 mA) for around 30 seconds to ionize the gas. Afterwards, it settles back to 10 mA. Unfortunately, my power supply can only supply up to 10 mA and cannot supply that 100 mA draw during the first few seconds.

To combat this issue, I was considering using an inductor. Would this work? Also, what would the specs of such an inductor be?


texts: Antenna sector power ratio (total power)

texts:
This is maybe a very basic question, which is driving me insane, because I can't remember the theory and neither I can seem to find any source about the topic.

I have an antenna, whose SPR (sector power ratio) is defined as the ratio between the co-polar field amplitude irradiated in a defined sector (let's say from -60° to +60° in respect to antenna's boresight), and the co-polar field amplitude irradiated outside of it plus the cr-polar field amplitude irradiated anywhere.

All the formulas I am finding simply reduce the problem to:

Sigma(Ampl Co in Sector) / [Sigma(Ampl Co out Sector) + Sigma(Ampl Cr everywhere)]

where Sigma is the sum of the amplitudes by each angular unit.

Now, the doubt that was raised to me was that since the two polarizations (+45° and -45°) lie with 90° angular difference from each other, they would lie on different vectorial planes too, therefore the sum shouldn't be the "normal" one.

Shouldn't the sum in this case be the quadratic sum? So basically:

Sigma(P Co in Sector) / Sqrt{[Sigma(P Co out Sector)]^2 + [Sigma(P Cr everywhere)]^2}

Is the following formula correct?

10*log{Sigma(P Co in Sector) / [Sigma(P Co out Sector)^2 + Sigma(P Cr everywhere)^2]}


texts: What kind of laser should I get to cut fabric?

texts:
I'm brainstorming a new project with my wife and was wondering
what type of laser I could use to cut multiple layers of fabric?

F.Y.I.
I'm a total noob when it comes to lasers and integrated electronics.

Update

The laser would be mounted on something that moves it on the x and y axis.
I want to cut through stacked layers of fabric.
I want to build a machine to cut out patterns on fabric to make cloths and what not.

P.S.
You should really let new users create tags.
I wanted to tag this question "lasers" and couldn't.


texts:
I need a bjt that can be used for serial transmition in the range of 50MHz and therefore needs a fast turn off characteristics. I'm looking for parameters as storage time and fall time but these are seldom mentioned in the datasheets. Are there other parameters I can take as reference for a fast turn off behavior? I assume a small collector base capacitance is also desirable. Would something like the MMBT5179 be capable of driving 50MHz signal when some additional turn off boosts (e.g. saturation limiter) are in place?
The one that is currently used is an MMBT2222 in an SOT-23 package, so the new one would need to be in the same package.
Looking at the signal at the transistor base, the fall time looks okay, at least much faster than the one on the collector.

update:
Here is a measurement of the transistors base voltage. I'd say the switch off looks okay and seems to be fast enough.

And that's the voltage on the collector (not the same bit-pattern though). The problem in my opinion is that the third turn off pulse (1bit width) doesn't rise fast enough, therefore not reaching 5V and as a concequence my laser diode doesn't turn of properly. What is the cause of the capacitive effect we see starting at 3.26V? C305 and C307 are removed but the signal shape didn't change significantly.


texts: Inherent Pseudo-Randomness in modern FPGA design tools

texts:
Do Place & Route algorithms of modern FPGA design tools ( Qaurtus / Vivado / etc... ) have inbuilt randomness in them ?

I.E:
Would it be possible to get 2 different results when compiling the same design twice ( given the same software version ) ?


texts:
This is specifically a high-level hobbyist question, I'm not really looking for schematics or anything of the sort.
To deliver Ethernet over Coaxial, what sort of high-level designs or common issues will I need/face in completing this task? Initial research found that this technology is also referred to as MoCa, see:
Multimedia over Coax Alliance
From my understanding, I need to essentially build two modems.
I'm just looking for a starting point to begin my own research, any help is very much appreciated.


texts: NCP1117 Regulator voltage feedback not working correctly

texts:
I'm having a brain fart. Reading 3.1V ish on the output. My +5V0 net is after a schottky diode with 5V + a little bit coming from the NCP1117, and another 5V0 coming from a USB connector. Reason being I want the regulated voltage after the diode to be 5V, accounting for the diode voltage drop.

My feedback resistors look fine, I checked the parts on the board and they look fine, and my input looks solid too.

After the +5V0 net is a 3.3V regulator for 3.3V logic stuff. That's about it. The +5V0 only powers a handful of devices which seem to be functioning correctly with the 5V0 USB going through the diode and only powering to about 4.6V.

LINK TO DATASHEET

Any clues?

Thanks in advance


texts: USB 1.0 Host speed negotiation to USB 2.0 Device

texts:
What is the negotiation sequence of a  Low Speed (USB 1.0) Host connected to a High Speed (USB 2.0 Device) ?
On connection the Device pulls up the D+. If this was HS/FS the Host would pull the D+ down - transmit SE0, followed by the device K chirp. But in this case the LS Host is waiting for a D- pull up connection event ?


texts: Use of relay in a gas sensor (safety issue)

texts:
I have developed an MQ-5 based LPG gas sensor which uses a relay.

Is the relay itself a fire hazard (while switching) if gas is in the vicinity ? Thanks.


texts: Difference between drain and source current

texts:
I was looking at this P-channel MOSFET datasheet and I am a bit confused.

(Source: Vishay Siliconix Si5435BDC Datasheet)

How it is possible to allow for a different current for the source and the drain? The datasheet states more A for the drain than the source. As I get it all the current that enters drain must exit the source. Where the extra current for the drain comes from?


texts: Meaning of S11 performing a clockwise arc circle about the smith chart origin?

texts:
I've tested a device with my VNA. It displays S11 in a Smith chart as a plot x(w) + iy(w) (w the frequency). Curiously, as w increases from 50KHz to 600MHz, the plot is an almost perfect 1/3 circle whose center is the origin of the Smith chart.
In particular, this implies that the absolute value of S11 remains constant in the frequency range.
This is not to be confused with the constant VSWR circles since these circles relate the plots to the length of a transmission line at fixed frequency.
I am curious to know what is the physical meaning of these circles (how to interpret them).


texts: How to convert 2 phase power supply to 3 phase power supply using a Transformer (like Scott transformer)?

texts:
I'm looking to develop a circuit to convert 2 phase power supply to 3 phase power supply.

My circuit follows:

Input:
2 phase 400V - phase angle 120degree

Expected output:
3 phase with phase to phase voltage as 440V - 440V - 440V

But
Actual output:
610V - 440V - 150V

There is some problem with phase angle conversion..
Help me fix this.


texts: What is the difference between clamping a input signal at X volts and clamping a input signal by X volts

texts:
I know that the total swing of the signal remains the same.I don't know how the circuit will be designed when it's asked to clamp the signal at X volts.
Will the lower peak be at X volts? Or the higher peak?


texts: Why were coax cables used for networking?

texts: Often, if older standards become obsolete, it's because they are superseded by newer technologies. In the past networking was done using coax, instead of the twisted pair used today. Why did they use the more expensive coax? It doesn't look like the twisted pair technology didn't exist back then, so technological advances don't seem to be the reason.


texts:
I am currently studying Practical Electronics for Inventors, Fourth Edition, by Scherz and Monk. Chapter 2.5 Resistance, Resistivity, and Conductivity presents the following image (without description) when discussing the concept of resistance:

I have the following questions:

What does the \$ A \$ symbol pointing to the left-hand-side of the Ohmic material represent?
What does the arrow going through the battery symbol represent?

I would appreciate it if people would please take the time to clarify this.


texts: Why is via fencing not used to cover the whole PCB?

texts:
Via fencing is used to reduce electromagnetic interference in critial parts of a PCB.
My question is, why do we not just cover any ground pour of the PCB with via fencing? Are there disadvantages that would come with that?


texts: Setting a part's VCC slightly lower than board's supply voltage

texts:
I'm interested in using the undervoltage detection feature (in addition to the primary function) of this chip. This IC draws 6 uA (microamps), and accepts any VCC between 1.6V and 5.5V.

The undervoltage detection works like this: When VCC of this IC is below V_threshold, it will declare an undervoltage condition and set a LOW on its "Enable" Output Pin.

Now, the problem is this:

While the IC is available with multiple variants of V_threshold, the only available variants available are V_threshold = 2.0V, 2.9V, 3.1V, or 3.3V at most.

However, I wish to cut-off at threshold of 3.5V. I'm using a Lithium ion battery to supply the VCC pin of the IC; the battery's supply voltage would range from 4.1V (maximum) to 3.5V (my desired cutoff).

So, for the above situation in particular, which of the following options (or something else) might be the best solution for creating a smaller voltage locally for the IC's VCC, and why?

Choice 1) A diode? To create a constant drop between the battery source and the VCC pin of the IC.
or Choice 2) A resistive divider? To set a proportionally smaller voltage at the VCC pin of the IC.
or Choice 3) An LDO regulator? With 3.3V output, placed between the battery source and the VCC pin of the IC.


texts: Draw relation of rotation speed and output power of PMAC generator with brake resistor

texts:
I would like to draw a graph showing the relationship between rotation speed and power of an ideal Sinus PMAC generator

with a brake resistor R(load) to be defined
controlled via a 4Q Controller acting as recifier
based on datasheet figures (=> cannot measure, known figures see below)
ignoring losses

In the end I want to know if I calculate the impact of the load resistor correctly. Here a schematic as an example. The load resistor replaces the main battery since I only use it for braking:

Datasheet only contains torque constant. (Calculating Back EMF from Torque Constant)

Assumtion: BEMF constant = Torque constant * SQRT(3) / 2

Here is, what I have up to now:

Assuming 1 Rotation per sec => rad speed $$\omega = 1*2*\pi = 6,28$$
\$U(sin) = \omega \frac{\sqrt{3}}{2} = 0,653 V\$

By substitution of U with I*R(L) of the following formulas:

$$U = \phi _{m}* \omega -I*R _{i}$$
$$U = I*R_{L} $$

I got:

$$I =  \frac{\phi _{m} \omega}{R_{i} + R_{L}}$$

$$I = \frac{0.12*6.28}{0.065 + 0.065} = 5.8A$$

$$P = I * U = 5.8A * 0.653V = 3.8W$$

At a rotation speed of 3400 rpm I would get 12kw of mechanical braking power.
Does this make sense?

I would prefer a calculation without magnetic field theory - if possible...
Thank you :)

Datasheet:

12kw continuous, 30kw Peak
Phase to Phase winding resistance is 0.065 Ohms with 20 turns per phase.
Voltage: 0 to 72 VDC input to the control
Torque constant of 0.12 Nm per Amp
The Inductance Phase to Phase is 0.05 Milli-Henry
Current: 165 Amps AC continuous (200 Amps DC into the motor control)
Peak current: 450 Amps AC for 1 minute (620 Amps DC into the motor control)
Peak Stall Torque: 75 ft lb.
4 pole motor (8 magnets)
Maximum recommended rotor speed: 6500 RPM
Armature Inertia: 45 Kg Cm Squared


texts: Practical designs/practices for home electronics

texts:
I need an automatic voltage stabilizer. I'm thinking about building my own.

I've searched the internet and consulted several books. The diagrams in books show only the bare bones, basic design that is intended to illustrate the principles of physics at work.

I'm sure professional grade products are more sophisticated.

As a software engineer I read code of open source software to learn professional practices. Can I find something similar in electronics?

Is there an organisation that publishes such designs? Has some professional electronics company released the design of its old products?


texts: How can I test my radio module without software to be sure it is not physically broken

texts:
I have recently bought a modtronix InAir9 radio module that I use with a Raspberry PI Zero W to play with the LoRa network.

I followed multiple tutorials with different software to try to make it work on the raspberry but without any success. Everytime it is like the module is not connected to the board. I have checked and rechecked (and even made it checked by someone else) that everything is properly connected where it should be.

Now I am starting to think the radio module might be damaged but I can't be sure, it might just be me not using the software properly (but I don't think so since it is pretty straight forward). Is there any way I can test my radio module to check if it is damaged without a software running on my raspberry? And if so, what would I need?

Here is some links to the module and tutorials:

InAir9 radio Module

pySX127x library with test and tutorial

loragateway library with step by step turotial and schema


texts:
I'm interested in creating a board that takes USB 3.1 and routes it to a FPGA. I'd like to do this without any of the chips like Cypress FX3 because I'd like to see the actual USB data.

To do this however, I'm struggling to find what type of I/O signalling that USB 3.1 uses. Is it Current Mode Logic?


texts: What is the difference between the order LP filter + Op-Amp and Op-Amp + LP filter in practice?

texts:
I have issues explaining what really happens on my circuit. I'm trying to make a cardiofrequencemeter with a white LED and a phototransistor. Basically I light the phototransistor, and measure the voltage of the collector and filter/amplify it.

In the order, I use a passive High-pass filter to eliminate the DC component (cutoff frequency at 0.5 Hz), then an active Low-pass filter to filter electronic noise (cutoff frequency at 4Hz) and amplify in the end.

My actual problem is that when I put HP filter + Op-amp + LP filter : I don't get my heart rate but measure other random light variation

But when I put  LP filter +HP filter + Op-amp : I measure the hear rate with peaks in the output of my circuit.

What did I miss?

Thanks !


texts: How to burn bootloader to ATmega 2560 using Atmel Studio and AVRISP mkII?

texts:
Although my question might come familiar to many Arduino developer including me, but, I am somehow lost burning bootloader to ATmega 2560. Many comments I found were related to AVRDude (never used before, maybe I should but later).

I usually use Atmel Studio with AVRISP mkII in order to flash my firmware to ATmega 2560 on a custom PCB.

Now, I need to use Watchdog timer. If I use it, MCU keeps restarting every interval I set (which is 8 seconds). After little search, i found there is a bug for some bootloaders. So, I therefore have to change the bootloader. (Correct me if I am wrong).

I can share some screenshots about my attempts;

After all this I click Program. After the process is done, Programming: Flash...OK appears. I believe it burns to the MCU.
Because, my existing program is not working anymore.

At this point, in the first place, I thought, this is it.
Then I flashed my own firmware (this time with watchdog timer included) using the same tool/settings as above except HIGH fuse I am using D0 instead of D8.

But again, MCU keeps resetting every 8 seconds. Means, bootlader issue persists.

What do you think?

Note that: the HEX file I am using for bootloder from the Arduino path as you can see in the screen-shot 3rd.

Note that: I have noticed after I created that question under electronics instead of Arduino SE, my apologies.


texts:
I want to make sure I understood this correctly .
If I want to measure the load resistance of this circuit, is it between (A - G) ?


texts:
I want to create an eye mask which I can apply at the Rx eye diagram up to which I can quantify the quality of my signal at the Rx. Now my question is what are the specifications to determine eye mask which is standard? I am creating SERDES channel with different channel parameters. Now at the Rx by looking at the ripples of the voltages, I can say which is good or bad. But that is not enough for the documentation of my thesis conclusion. I have to quantify with a quality. I can create an eye mask with a defined parameter, which I can say keep out of zone area. Now I am not asking now how to make the file. I am asking based on what I will specify an standard eye which I can apply and say that if it crosses this eye mask the signal integrity is not good at the Rx. Can anyone help me? I know the mask region is defined as follows:

  Top region: The maximum expected value. Voltages exceeding this value will fail.
  Middle Region: The size and shape of the eye diagram as defined by the interface standard for the high speed digital signal.
  Bottom Region: The minimum expected value. Voltages below this value will fail

Now I am confused how to specify those regions — based on what?


texts: Where does the name TO-220 come from, and what significance does it have, if any? I am aware it is a JEDEC standard but wonder what is the origin of the package name?


texts: Why doesn't voltage drop across this resistor when transistor is off?

texts:
The following excerpt from a book explains the functioning of the circuit below:

  When V_in < V_th (device threshold voltage), the supply voltage (V_dd) is measured at the outlet.  When V_in is increased above V_th, the NMOS turns on and V_dd is now dropped across the load resistor; V_out is now in common with ground, and the signal at V_out is inverted relative to V_in.

Question:  Why is V_out = V_dd when the NMOS transistor is off (i.e. when V_in < V_th)?  With the transistor off, it seems we should effectively be able to ignore that part of the circuit and compute V_out using Ohm's law to predict the drop of V_dd across the resistor.  Why is this not the case?


texts: How to Swap Cathode with Anode in LED MATRIX 5X7 In proteus?

texts:
Hi in Proteus 8 the given model of Led Matrix 5x7 has Anode on Column side and Cathode on Row side.
I want swap it and Hence Column would have Cathode and Rows will have Anode and my Second Connection Start working(which is now not working) Unlike the one working now and turning the Led on.
Any Help would be Appreciable
:)


texts:
On semiconductor wafers there is a straight line, which is called Orientation Flat.

What exactly are these and how they are formed?


texts: What does "reconductor" or "reconductoring" refer to?

texts: This is a term that I seem to remember hearing in reference to electric transmission. I'm pretty sure it has something to do with upgrading a set of transmission lines to carry more current, but I'm not totally sure. Am I correct here? Can someone please give a thorough explanation of what reconductoring is?


texts: Piggyback input power from supply power on SSR?

texts:
I would like to use a reed switch to control a solid state relay. Could I use the supply power for the control aswell?
Thanks for your help.

https://imgur.com/gallery/p9oa3Ll


texts:
I've been trying to understand how plasma lamps (or plasma globes, according to Wikipedia) work and why you don't die a horrible fiery death when you touch them. What I've got so far is that the center electrode is fed a high voltage and high frequency input. Due to the high voltages, the gas ionizes and you get the plasma filament thingies. All this makes sense, but I have some questions I can't answer (or find the answer to online). Firstly, related to how current kills:

What current is needed to harm you? I've heard of the milliamp current that causes fibrillation, but I'm talking about actual burns and people on fire. Human bodies are resistors typically on the MOhm range (as confirmed by my multimeter and me). Even with main voltages (220 where I live), that's a ridiculously small current, not even milliamps. Also, the power you dissipate is like 0.1W, which shouldn't be terribly harmful. Can you be severely burnt (in dry conditions) with mains voltage?
Now onto the Plasma Ball part:

What is a good equivalent circuit for the ball? Maybe if someone could supply an equivalent circuit, I could understand it better.

Why does it need to be high-frequency?? Wouldn't a few kV ionize the gas just the same?

Which parts of the lamp are grounded? It does seem to make a difference whether you're grounded or not when you touch it. Also, why does the filament concentrate on your finger when you touch it? It seems as though you're closing a circuit with ground, but this seems weird because of question 1.

Why isn't this extremely dangerous?!?! Under right, but not too unlikely circumstances, if you're standing on the ground and offer a low resistance, the center electrode on the kV range would output a current on the amps range or even more (assuming the reference of the center electrode is actually grounded). This should at least fry you right where you stand, if it doesn't cause fibrillation before. I understand it would be pretty stupid to touch one of these lamps standing bare foot on the ground and wet, but you wouldn't get just shocked, a few amps would make for a gruesome spectacle, right? How can you sell such a thing to the public? I've heard people say it's not that harmful because of the high frequency but how can that be the case? Does the human body stop behaving like a resistor at high frequencies?

On a similar note, if I had the lamp on a metal table and someone were to tip it over, a few kilovolts short circuited to ground have got to create some fireworks. Isn't this really dangerous? I know that probably the power supply inside won't be able to supply the amperage and the voltage will drop, causing a smaller current, but again, isn't this really dangerous anyway?


texts: How does power affect the TP4056 module?

texts:
I have 4 questions in particular:
TP4056 input has been given as 5V and 1A.

How does TP4056 handle the charging process it more than 5W is provided to the module? Will the battery stop charging or will it damage the cell? Also how much more than 5w it will keep charging the batteries?
If I provide more power than 5W but the current is less than 1A but the voltage is higher making the power more than 5W then what will happen? Will it charge the cell properly?
If I provide more power to the TP4056 so will it be possible to draw power for load from the output point of the module?
If I attach 2 wire at both positive and negative terminals of the cell then draw power from one of the circuits and use another for charging so when the battery will start charging will it automatically stop discharging or there will be another case?

If I made any mistake in asking a question or something seems irrelevant, please correct me on that.


texts: Computer Power Supply to bench top theory

texts:
I want to use my Corsair 430CX as a benchtop power supply to do small circuit work. I am fuzzy on the theory however when it comes to the amount of amperage that the rail can support. It worries me, the amount of current possible that can come out of these rails and i want to know what I am dealing with in terms of working with small circuits.

I understand ohms law to the extent that the voltage should be the determining factor in whether or not i release magic smoke, I mean this in the sense that wattage or volts * amperage does not come into play when working with circuits. I may be entirely wrong on this front. I picture myself connecting a 1/8 watt or 1/4 watt 1MOhm resistor across a 50aH 12v car battery and can't believe in the math. I feel like I would release magic smoke and endanger myself.

Can someone validate the theory or enlighten me because all that I have read so far makes me think I can create small circuits with a 12v 30amp rail and 300+ watts and be fine when I picture it being very different from working with a small a23 12v battery. Surely these cannot be the same things, can they?


texts: Help with understanding strange capacitor configuration arrangement

texts:
I am on a chapter of my electronics beginner’s book where the author talks about the PICAXE microcontroller. One of the first things the author mentions in this chapter is to make sure that the PICAXE microcontroller power source capacitor configuration looks something like this:

Right of the bat this configuration looks strange to me because of the need for using two different types of capacitors in parallel. My first thought was why not just combine the two capacitors and use one bigger one instead?

Also, interesting to note is that the bigger capacitors sit further away from the LM7805 than the smaller capacitors. Why not place them the other way around? There must be a good reason for this.

Could someone offer an explanation for this awkward capacitor configuration need?

Thanks.


texts: Why do we need to find power spectra of different line codes? why we relate it to to the auto correlation of the signal? how does it help us in  transmission of digital signals?


texts: Verilog : Combining sequential logic with combinational logic

texts:
I am trying to implement a sequential shift and add 4bit multiplier as shown in the image.

I am having a separate module for the 4 bit ripple carry adder. I have tested the adder module and it works fine.

now i need to trigger it from the multiplier module. so that it triggers on the 'add' signal.
please help in modifying the ripple carry adder code i have included the code for reference

main module code which does not compile since i have included the rca4bit module inside the sequential always block

    `include "rca4bit.v"
module seq_mult_4bit(output [7:0]product,input [3:0]a,b,input clock,input reset,input start);
    //reg prod[7:0];
    reg multiplicand[3:0];

    parameter WAIT_STATE = 0, LOAD_STATE = 1, ADD_STATE = 2,SHIFT_STATE = 3;

    always @ (posedge clock)
    begin
        if (reset)
            state <= WAIT_STATE;
        else
            case (state)
                WAIT_STATE:
                    if(start)
                        state = LOAD_STATE;
                    else
                        state = WAIT_STATE;

                LOAD_STATE:
                    //load data into registers
                    product[3:0] = 4'h0;//load accumulator with zeros
                    multiplicand[3:0] = a[3:0];
                    product[7:4] = b[3:0];
                    //read lsb
                    if(product[7] == 0)
                        state = ADD_STATE;//only add if there's a 1 in the multiplicand
                    else
                        state = SHIFT_STATE;//else move to shift state directly

                ADD_STATE:
                    //add the partial product
                    rca_4bit adder(product[3:0],c_out,multiplicand[3:0],product[3:0], 0);//adder block

                SHIFT_STATE:
                    product = {c_out,product[7:1]};
                    count = count + 1;
                    if(count == 3)//wrap around
                        count = 0;
            endcase
    end
end module

//state machine

module code for ripple carry adder

`include "fulladder.v"

module rca_4bit(output [3:0]sum,output c_out,input [3:0]a,b,input c_in);

wire c1,c2,c3;

full_adder fa1(.in_x(a[0]),.in_y(b[0]),.c_out(c1),.sum_out(sum[0]),.c_in(c_in));
full_adder fa2(.in_x(a[1]),.in_y(b[1]),.c_out(c2),.sum_out(sum[1]),.c_in(c1));
full_adder fa3(.in_x(a[2]),.in_y(b[2]),.c_out(c3),.sum_out(sum[2]),.c_in(c2));
full_adder fa4(.in_x(a[3]),.in_y(b[3]),.c_out(c_out),.sum_out(sum[3]),.c_in(c3));
endmodule

please help!
PS:i am new to verilog so please excuse my noobness :)


texts: How to read high impedance on pin Arduino?

texts: The goal is to catch an AC leak. For these purposes, I use a measuring transformer (RCMB121). When there is no leakage, the output contacts are low (GND). If an accident occurs, the contacts go into a high impedance state. How can I read high impedance condition with Arduino Uno? As I understand it, this is not a HIGH level. Can I pull these contacts resistors (10k) to the power line?


texts:
Is there any breakout board like this for 1.27 mm to 2.54 mm pitch?

Example for 1.27 mm:

Example for 2.54 mm:

I also appreciate any hint how to perform this conversion on any other cheap way.


texts: How do I use an LEDs wired for 277V AC on a 12V DC power supply?

texts:
I have some LEDs that I am trying to re-purpose.  They were originally running on 277V AC.

The LEDS are soldiered onto a pretty large board with just two wires coming out.  If I measure the voltage coming from this board it is around 240 volts DC.

The 277V AC goes into this board and 240 DC is coming out.

Can someone explain what I need to purchase make these light up from a Car battery?

Thank you!


texts: Grounding Metal Object to Eliminate Static Electricity Using Electrical Ground

texts:
let us say that I have built a metal cabinet in which I will be painting small objects. I am looking to eliminate any static electricity that could possibly build on the object to be painted or on the cabinet. The object will rest on a metal turntable which will rest on the metal cabinet, which I am hoping to be able to connect to ground.

Can I connect the metal frame of the cabinet to the ground (third prong) of a nearby outlet to ground the entire cabinet and part and possibly eliminate any static electricity?

By "Can I," I am hoping to hear responses regarding the efficacy of this method of static elimination and regarding the safety and possibly electrocution hazards of this method.


texts: What is a good process to replace a discontinued part?

texts:
I have been looking about (on the web and printed catalogs) attempting to replace a part that is now discontinued.

The experience has been part success - and part failure.
A part is available to use if I update a board design to use a different package - but not a drop in replacement.

And so, I inquire - what is a the process or technique individuals in the electrical engineering field apply when they must replace/update a part/design with either of the following criteria:

Equivalent replacement (you want to keep the same design or minimize changes to that design, e.g.; a discontinued part burned out - drop-in replacement).
Complete redesign (you have a design that uses older parts - thru-hole components, etc - and you want to update that design with smd parts, but some of your old parts are discontinued and no obvious replacement part is available).

For reference, the part I am looking into is the M54564P/FP - I am thinking the A2982 is a good candidate - but it requires updating my board design and so, not a drop-in replacement. Any tips?


texts: Inrush and steady state current in an Inductor with AC voltage

texts:
I have two statements here from two great men.

One says

"If you apply AC voltage to the solenoid at the peak of the waveform then there is little or no inrush current whereas if the solenoid is connected to an AC source as it passes through zero volts then the current waveform in the solenoid can reach an excessive value that causes magnetic saturation of the solenoid core and make the problem of inrush even worst"

other one says

"The transient depends upon the contact timing referred to the AC voltage applied, if the contact happens at any AC voltage peak, there is no transient at all (the current becomes a 90 degrees delayed wave straight away) while the transient will be maximized when the contact is achieved at any AC voltage zero crossing, the superimposed current will looks like an asymmetrical Gauss bell (very steeply at rising side)."

My question is why there is transient current or inrush current when a ac source is connected to an inductor at ac voltage zero crossing and why is there is no transient at ac peak voltage ?


texts: Does a pinch imply the presence of memcomponents?

texts:
There is a famous article by Chua "If it's pinched it's a memristor", where he defines a memristor as having a "[...] pinched hysteresis loop in the voltage–current plane when driven by any periodic voltage[...]", in particular he states the pinch must be at V=0. The problem I have is that I'm characterizing a component which has a pinched hysteresis loop like this for example , where the pinch is not at zero (in the article he calls this an imperfect memristor). In my system the pinch also disappears with different driving frequencies

What I want to know is if the presence of the pinch is enough to know that there are mem-components in my system. I know for sure it's not only a memristor because it has a capacitance for example. Is is possible to get a pinched hysteresis loop without memcomponents ever?


texts: What is the purpose of this grid on the ground plane near a wifi antenna?

texts:
The PCB for this Steam Link has a grid of squares near the antenna. It also has pads for what I guess is either testing or adding 0ohm resisters.

What is the purpose of this feature, and why are there pads on it?

An album with a picture of the full PCB can be found here, if that's helpful.


texts:
I would like to ask a simple question. I do have controller whose  pins are configured were configured as o/p. The controller runs at 3.3v and it's from the Pic18f family of controllers.Why is it that the o/p pin shows only voltage of 2.23v when configured as o/p. Is it the maximum or should it show >3.0 v.

It's been on my mind for some time. Is it a natural thing or some configuration mishap?

I would like your take on this phenomena.

edit:

Void main() {
    TRISD=0x00;

    while(1) {
        PORTEbits.RE2=1;
    }
}

Regarding schematic all the Vdd and Vss pins were connected to 3.3v and gnd respectively.


texts: Need proofing on this 12v battery protection circuit

texts:
I am making a battery protection board for my 12v battery. The amperage pulled from the battery could go up to as much as 20A. I want the Arduino (connected to the protection board) to activate the relay, and open the circuit in the case of overcurrent or over-discharge (using spectroscopy to detect the battery SoC).
The problem is that I need proofing on this. I am kind of a newbie to this and lacking confidence in whether this circuit will actually work.
NOTES: The flat ground symbol is for the battery's ground. The triangular ground symbol is for the Arduino's ground

Is there anything missing/ unnecessary/ wired incorrectly that could cause damage to any part of this circuit or the Arduino?

are the values for the resistors (R1,R2,R21) correct? I used ohms law, but something tells me on R1 and R2 that .25Ω is not sufficient to reduce the 12v 20A down to 5v. Same concerns for R21.

… And do I need to add a resistor to from the Arduino digital pin, to the transistor?

Will this circuit enable the Arduino to use ohms law to get the amperage from the battery? if not what changes must I do to the circuit, or is it even possible?
Lastly, does this circuit provide all the data necessary to the Arduino for the Impedance Spectroscopy State of charge (SoC) method?


texts: How do I change the PWM frequency on an Arduino Uno

texts:
I currently trying to change the PWM frequency from the the standard 490 Hz to something else, Literally something else.

I previously used a timer1 library available from the Arduino, but became annoyed by it an began setting up things manually.

#include "test.h"

test::test()
{
  pinMode(10,OUTPUT);
  //Timer1 setup1 Interrup at 1hz
  cli(); // Stop interrupts
  TCCR1A = 0;
  TCCR1B = 0;
  TCNT1 = 0;
  OCR1A = 15624; // Compare register value = cpu_fre/(interrupt_freq*prescaler)-1 (must be <65536)
  TCCR1B |= (1 << WGM12);
  TCCR1B |= (1 << CS12)| (1 << CS11) | (1 << CS10);
  TIMSK1 |= (1 << OCIE1A);

  sei(); //allow interrupts
}

ISR(TIMER1_COMPA_vect)
{
 digitalWrite(10,!digitalRead(10));
}

here is the main

#include "test.h"

test test1;

void setup()
{
Serial.begin(230400);
  // put your setup code here, to run once:
}

void loop()
{

}

This should should create an interrupt each 1 Hz changing the state of the pin.  but instead creates a 490 Hz PWM signal...

Changing the prescaler or OCR1A only changes the duty cycle of the signal, and not the frequency itself..

What I am doing wrong here?


texts: How to read this memory map of LPC1769 microcontroller?

texts:
I'm trying to understand the memory map of the LPC1769 microcontroller using the official NXP datasheet. The screenshot below shows at 0x00004000 to 0x00008000 there is 512kB of flash memory mapped, however the number of addresses between 0x00040000 and 0x00080000 can't reference all 512kB of flash memory?

How does this mapping work so all 512kB can be referenced? Or have I misunderstood something?


texts: How this DIY High-Speed Probe doesn't reflect signals?

texts:
I am reading The Art of Electronics, page 809 and 810, where they show this probe:

Which is a DIY probe, made out of a RG-178 coaxial cable, in series with a 953 ohms resistor.

I wonder why the 953 ohms resistor is needed, won't it reflect any signals entering the 50 ohm, instantaneous impedance, coaxial cable? Is it for limiting the current out of low frequency signals? Or is it just for creating a 20x probe (1k/50R = 20)? Then what's the benefit of a 20x probe and not 10x? For me it looks like a big inductor for high-frequency signals, and the book doesn't specify any special, low inductance, resistors to be used.


texts: Do any flip-flops use separate clock levels for "sample" and "propagate" events

texts:
Many kinds of sequential logic require that the output of one register be fed into the input of another register which is strobed by the same clock.  In such logic, it's necessary to ensure that a changed output from the first register cannot affect the input of the second until after the hold time of the second register has been satisfied.  If data flows in one direction, it may be possible to delay the clock of the downstream device, but if data needs to flow bidirectionally it may be difficult to ensure that all devices have sampled their data before any changes can percolate to any device's data input; getting reliable behavior from high-speed logic devices would require sharp clock edges even when using very slow data rates.

It would seem that in many cases this problem could be eased considerably if flip flops' clock inputs defined two distinct levels with non-overlapping tolerance bands: a "sample" level (perhaps 15%-30% VDD) and a "propagate" level (e.g. 45%-60% vdd), such that setup time would be required before the clock signal reaches 15% VDD, hold time would be measured after it reaches 30% VDD, minimum propagation would be measured after it reaches 45%, and maximum propagation after it reaches 60%.

Such specifications would ensure that provided every device sees the clock signal reach 30% of VDD before any device sees it reach 50% of VDD, then setup/hold times would automatically be met for any devices with a zero hold time; positive hold times could be met by limiting the rate of rising clock edges.

It would seem that this approach should allow system designers great flexibility in balancing clock edge speed with clock rate requirements, and would allow much better noise immunity than Schmitt trigger inputs (unless all registers are clocked by the output of the same Schmitt trigger, they may switch at different times, and even when using one Schmitt trigger, logic may get sunk if a fuzzy clock signal makes the output go metastable).  Are there any logic families that use such behavior to improve the performance and reliability of their edge-triggered logic functions?


texts:
I have 32 GL10516 photoresistors, groupped (logically) in 4 arrays of 8 resistors.

Each photoresistor is connected to one voltage-divider. I want to measure those output voltages using an 8-channel ADC (https://www.abelectronics.co.uk/p/65/ADC-Differential-Pi-Raspberry-Pi-Analogue-to-Digital-converter).

What is the best solution to switch those 4 arrays one by one to the ADC?


texts: Need help understanding the status output generation of an ALU

texts:
I'm currently trying to implement a simple processor using Verilog in a FPGA. I'm using Mic - 1 architecture as a reference model.

The thing I can't understand is the ALU is generating a "status" output when a certain operation is completed. How the ALU exactly know a certain operation is completed? Because each operation may take different number of clock cycles to complete. For example multiplication may take many clock cycles than single addition because multiplication need several bit shifting and additions.

Is this time delay should be pre-defined in ALU?

MIC-1 architecture is shown below.


texts: Proper setting of a magnetic trip breaker

texts:
I have separate interrupting devices in an MCC bucket.  One is a magnetic trip-overload 250A breaker, where the lowest trip setting is 1100A.  The other is an electronic device that has 3 CT's and gives me options of trip class, ground fault, phase imbalance, etc...

A 90kW, 3 phase 480V uncoupled motor is tripping the magnetic overload.  Initially I thought phase imbalance (hence other post) but I realized that would only appear in the electronic trip.  With a fluke meter we recorded peak currrents of 200A, 422A, and 448A, none of which were close to the minimum 1100A instantaneous trip.  However, an old timer explained that the magnetic trips are extremely sensitive and have to be such much higher.  Normally when I think of a trip value I think of 6x rated current for full-locked rotor value, but for magnetic trips it appears this is not the case.  We bumped the settings up to 1700A and it resolved the issue.

In this situation, is there any type of rule of thumb for choosing a successful magnetic trip setting (example, 10-15x FLA?), or at least a start point, for a 3 phase motor of this size?

It seems after incrementing to 1700A, and then 1900A, the tripping condition still exists intermittently.  The breaker tripping is a Siemens FXD6-A (FXD63A250 C Series).  I checked current while running and I had less than 10% imbalance, looked pretty normal, running less than FLA (114, 106, 106).  Right now I'm looking for the trip curve.


texts: Resistor values for adjustable voltage regulator

texts:
I'm using a LT1529 voltage regulator and I'm having a hard time understanding the process for determining the resistors to use in the voltage divider.  The datasheet provides the following schematic and calculation:

  ADJ (Pin 2): Adjust Pin. For the LT1529 (adjustable
  version) the ADJ pin is the input to the error amplifier. This
  pin is internally clamped to 6V and – 0.6V (one VBE). This
  pin has a bias current of 150nA which flows into the pin.
  See Bias Current curve in the Typical Performance Characteristics.
  The ADJ pin reference voltage is equal to 3.75V
  referenced to ground.

I want an output voltage of 4.0V.  The typical ADJ pin bias current (which I think is the desired current for the adj pin) is 150nA.  I'm not sure if I should use these values to determine the R2 resistor.  It gives a rather large resistance value (like 26.6M).  Once I know R2, R1 should be easy to solve for but I would appreciate confirmation on that value too.


texts:
Ive been messing with RC Low Pass Filters for a few days now but ive ran into a Problem: I cant seem to increase my slope. Right now im at 3db/oct (I think?). With a single pole RC filter. Ive tried stacking them but that doenst seem to do anything.

My source is an audio signal thats being amplified by a NPN transistor (with a DC offset so the ATmega can process it). Then I have my RC filter which seems to work fine but i need more attenuation.

From 150Hz on I want a 24db slope, what do I need to change? Audio quality is not a concern as its just being processed by a micro for beat detection.


texts: Finding the Transfer Function of Spring Mass Damper System

texts:
I have been going through Ogata Modern Control Engineering book and working through several exercises to improve my understanding of basic control principles. I came across the following example which I am struggling to solve.

I need to come up with the transfer function that models this vibration jig. The questions are as follows:

  In this example you will be analysing a vibration test rig (Fig. 1).
  This system consists of a table of mass M, and a coil whose mass is m.
  A permanent magnet rigidly attached to the ground provides a steady
  magnetic field. The motion of the coil, , through the magnetic field
  induces a voltage in the coil that is proportional to its velocity,
  ̇, as in Eq. 1.  = ̇ [eq.1]

  The passage of current through the coil causes it to experience a magnetic force proportional to the
  current as in Eq. 2.  =  [eq.2]

  Question: Obtain a parametric transfer function with output  to
  input .

Some questions I am finding hard to answer but affect the whole T.F are:

If K2 and B2 are compressed by a distance Z, (when moving upwards
due to the coil interacting with the magnetic field) does this mean
that k1 and b1 are extended by the same distance Z?
If m (coil) moves upward by 2cm, does M (table) also move upwards
by 2cm?

What I need to do:

Come up with two separate free body diagrams, one for the mass M of the table and one for the mass m of the coil.
Sketch one circuit diagram including back emf.
Transform to s-domain.
Solve simultaneously.

What I have done so far:

Draw to separate free body diagrams and extract equations.
Draw the circuit diagram and extract equation.
Convert to s-domain.

Using MATLAB function solve I managed to get 2 different 5th order transfer functions (one for each method I propose below), however, I am not sure which one is correct, and why.

Overall System :

This is a diagrammatic representation of how I think the vibration test jig can be modelled, excluding the electrical part.

Free Body Diagram 1 - Table - Upward Convention

Springs k1 and k2 and dampers b1 and b2 are modeled separately. Since they cannot be added together and viewed as one, their compression and extension are separate.

The upward force is coming from k2 and b2 which are attached to the coil. These are experiencing an upward motion.

Equation in the s-domain :

Ms^2X + b1sX + k1X = b2s(X-Y) + k2(X-Y)

Free Body Diagram 2 - Coil - Upward Convention

The coil is experiencing a force upwards, however the spring and damper are holding it back, thus acting in the opposite direction.

Equation in the s-domain :

Fem = Ms^2Y + b2s(X-Y) + k2(X-Y)

The two different methods are shown above for the FBD of the table lead to different equations in the s-domain and different transfer functions.

What is the correct Free Body Diagram for the table and coil?


texts:
i have a module, written in verilog, that gives me couple of warnings e.g.

  WARNING:Xst:1710 - FF/Latch  (without init value) has a
  constant value of 0 in block . This FF/Latch will be
  trimmed during the optimization process.

This is because the bit0 of register "krA" never changes it's state since I'm up counter it by 2. I want to know how can i workaround this warning, maybe if somebody showed me an alternate way of dealing with such a register that will have 1 or more more bits always at a certain logic/state.

Thanks for your time.

link to module : https://pastebin.com/zX4icWu3


texts: I'm building a linear voltage regulator using the LM 741 (part of school project) but everytime I connect a load than draws more than 1A the output voltage drops down. I'm not sure why this happens and what can I do to solve this ?


texts: How to measure VSWR of a single connector?

texts:
With a 2-port VNA, I would like to characterize the performance of a single coax connector, specifically to obtain VSWR.

The specific situation is an SMA connector at the end of a short section of semi-rigid 50 ohm coax that has no connector on the other end.

The two techniques I can think of are:

Add the same connector to the coax, creating a short double ended cable, and using the known electrical length, obtain the S parameters for one connector. I do not know the exact formula.
Try to terminate the coax with a 50 ohm load. I think that soldering a resistor would not work properly at these frequencies (>9 GHz).

Are there techniques I am missing?


texts: Is a stripboard strip designed for 240V?

texts:
I need to use a relay to control a 240V circuit via a low voltage (5V) one:

Beside making sure that the "high voltage area" is correctly insulated from users one point which worries me is whether the strips marked with a triangle are designed to be used with mains voltage. The expected current will be about 2A.

Which current are typically stripboard designed for? I am looking for an order of magnitude (100mA vs 1A vs 10A)


texts: contradiction in ripple calculation for buck converter

texts:
I am having problems understanding ripple calculation for buck converter here (from page 39).

First, the author makes an assumption that the capacitance is large enough so nearly all [not all] of the inductor current ripple flows through the capacitor, and very little flows through the load. This assumption is valid.

However, in the calculation in the next pages, the author is calculating as if ALL inductor ripple current flows through the capacitor, no current flows through the load. Then he calculates for ripple voltage.

However, if we use the assumption that ALL inductor ripple current flows through the capacitor, no current flows through the load then the output ripple voltage should be ZERO. It doesn't make sense to me.
There is a contradiction here.

What do you think about this?


texts:
I know that questions from a mechanical engineer might sound a little naive to you :), but here I go:
I am trying to use an Arduino Uno as the brain for a DC brushless motor that we have for a project. The motor has a quadrature 2-channel magnetic encoder as I understand(!).

IG52-04 24VDC 285 RPM Gear Motor with Encoder

How do I know what the sampling rate of the Encoder is? Or how do I know if an Arduino microcontroller satisfies our requirement for reading the shaft angular position through the encoder based on Arduino's sampling speed?


texts: How to solder a breakout board to a prototype board without edge castellation?

texts:
I have a prototype board like this:

I have a breakout board like this:

I would like to solder the breakout board directly on top of the prototype board without using headers, so that I can reduce the height of my prototype.

I am aware of edge castellation, but would prefer to explore an explore an alternative as I do not have access to anything besides the protoboard, breakout board, soldering iron and solder .
I would like to avoid using headers to keep the height of my prototype small.

Is it naive to think that I can just put solder or wire in the holes of both the Protoboard and breakout board, and get them to sit ? I can probably add some glue also to hold the boards together. Is this a bad idea ?

I do not expect much mechanical stress, as I will secure the prototype board to the case.

Any suggestion ? As I am just hacking a prototype together for demonstration purposes I do not want to go through the trouble of placing all the individual components of the breakout board on the protoboard.

EDIT: I'm trying to keep the footprint as small as possible so do not want to place the boards side by side. I would like to place them one on top of the other and minimize the height as well.


texts: Calculate the voltage across a load resistor for complex transmission lines

texts:
The following parameters are given:

500m homogeneous transmission line.

R' = 4.6 Ohm/km
G' = 0.5 uS/km
L' = 2 mH/km
C' = 800nF/km
r2 = 0.6 (sendondary side refl. coeff.)
ω = 200k
Uin = U1 = 60V + 0j

Question: What is the voltage U2 across the Load impedance ZL? For ω= 200k and Uin = 60V

My Idea:

Calculating ZW first (Wire Impedance)

Then calculating the Load Impedance:

Now i think about this circuit like two series impedances and i think i could use the resistor dividor approach to get the voltage u2 across the Load impedance:

Calculating:

Unfortunately this result isnt correct.
I am not be able to figure out where i did a mistake.

Do i have to take the refl. coeff into account again?

Would be happy about anything helpful.
Thanks.


texts: How to connect custom stm32 board to debugger

texts:
I have a custom STM32 microcontroller board. I have verified all of the electrical connections, and I am able to program the board with Texane's st-flash utility. However, I would like to debug the board as well, and I am having trouble doing this. I am using Visual Studio Code with cortex-debug extension. The extension (I haven't used the command line utility for debugging much, not sure if it has the same requirements) requires that I have the SVD file for the specific chip - something I was unable to find online. The chip is the STM32F439ZIT6. For other boards, including the F407 discovery, I have not had any issues programming or debugging the board, but I also already have the SVD files for those chips that I found online. So, my question is where can I find the SVD files? Or how do I make them?

Alternatively, I looked a bit into using OpenOCD to debug - however I have been unsuccessful in getting that working at all. The most success I've had is running

openocd -f interface/stlink-v2-1.cfg -f target/stm32f4x.cfg

but this hits the error:

Info : auto-selecting first available session transport "hla_swd". To override use 'transport select <transport>'.
Info : The selected transport took over low-level target control. The results might differ compared to plain JTAG/SWD
adapter speed: 2000 kHz
adapter_nsrst_delay: 100
none separate
Info : Unable to match requested speed 2000 kHz, using 1800 kHz
Info : Unable to match requested speed 2000 kHz, using 1800 kHz
Info : clock speed 1800 kHz
Error: open failed
in procedure 'init'
in procedure 'ocd_bouncer'

I think OpenOCD might be more powerful and something useful to learn, but from what I've found, there aren't many resources for using it with the ST-Link programmers and a custom board.

Thanks for help!


texts:
I have been trying to derive the S-parameters of a lossless T-junction of transmission lines. Here's a diagram from Google:

This is an exercise in microwave network analysis, not in design, so the purpose is to obtain analytical expressions, not a useful circuit. This is a theoretical question only, no Wilkinson dividers here, and no convenient values to get ideal matching or symmetry.

Background
Assume the T-junction is fed by a source Vg with source impedance Zg feeding a line of characteristic impedance Z0, connecting to a junction of two transmission lines, with characteristic impedances Z1 and Z2, and lengths of lambda/4 (quarterwave commensurate lines). These lines are terminated in loads of ZL1 and ZL2 respectively.

Denote the input impedance to line 1 (with char. impedance Z1) by Zin1, the input impedance to line 2 by Zin2, and assume they both have their own coordinate systems, with z=0 at the loads and z=-l represents the junction. The voltage on line 1 is V1(z), the voltage on line 2 is V2(z), so that, at the junction, V1(-l) = V2(-l) = Vx, and at the loads, V1(0) is the load voltage of line 1, and V2(0) is the load voltage of line 2.

That's all the background! It is simply to show that the input reflection, S11, is
$$ S_{11} = \frac{Z_{in,1}||Z_{in,2} - Zg}{Z_{in,1}||Z_{in,2} + Zg} $$
Which is the basic reflection coefficient. Calculation of S21 is not so easy. To help, we can calculate the line voltages (and currents), as (using V1 as the template, V2 is identical):
$$ V_1(z) = V_{0}^1 ( e^{-j\beta z} + \Gamma_{L,1} e^{j\beta z} ) $$
Where
$$ V_0^1 = \frac{V_x}{j(1 - \Gamma_{L,1})} $$
And
$$ V_x = V_g \frac{Z_{in,1}||Z_{in,2}}{Z_{in,1}||Z_{in,2} + Z_g} $$
These were derived by pretty straightforward analysis, nothing too tough, and I compared them with simulation to confirm. They've held up in every way.

The Problem
I wanted to obtain S21 from the line voltages and currents. I thought this would be simple, but it was not; no matter how I analyzed it, the results weren't making sense, and weren't agreeing with simulation. After much experimentation, I actually found that S21 varies with V1(0), with a correction factor that depends ONLY on the ratio of Vg to ZL1, the load resistor on line 1 (port 2 in the S-parameter context). After some experimenting, I obtained the following result:
$$ S_{21} = 2 V_1(0) \sqrt{\frac{Z_g}{Z_{L,1}}} $$
And this expression agrees with simulation even if Z1 and Z2 are different, or are changing, and even if ZL1 and ZL2 are different.

I was really surprised to find this expression. It's not unheard of to have square-roots in microwave analysis, but the square root of a ratio of impedances? For all my effort, I don't know how this happens. Why in the world does this expression work? Where does this come from? If anyone can shine a light on this, I would be forever grateful.

Can this value of S21 be derived?


texts: Is this the correct way to put a diode for flyback voltage protection to protect the infrared heater? And do I need to put a flyback protection for the Arduino pin or Vcc?


texts:
What will happen if I feed a 12 Volts rated PWM fan with 5 V driving voltage?

Given all the other variables stay the same (PWM control signals) - will it reduce RPM? By how much?

What happens to the RPM range window? Will it shift downwards? Will it shrink?


texts: op-amp thevenin resistance calculation in pspice

texts:
hi everyone so my question is how do i calculate the equivalent we see from Vo node (output of op-amp) in pspice beacause anything i do i get 0 value it will be appriciated if one of you help me to do this with pspice
and my circuit :
[![enter image description here][2]][2]


texts: BGA package, should I add some solder paste?

texts:
I've found that BGA balls actually melt. I've read that some say that it's advised to add some paste, some say to add flux and some say just to put the chip in place.

At the hobbiest level, without any special PCB manufacturing equipment and with hand placement, do you advise to add some solder paste in very small quantity, to be sure that all pads will have a contact and to allow correct alignment?


texts: Lightweight circular log (filesystem-like) algorithm for flash based storage

texts:
I am currently working on a project that involves rapid, continual logging of a rather application specific metric over a long lifetime.  To do this I ended up using an NXP M0 and a 32MiB SPI flash chip.  The logging is continual and needs to last many years in the field (10+), and is periodically checked by a human for trend spotting.  Eventually the buffer fills up and starts overwritting old data which is perfectly fine.  I came up with a simple algorithm to walk the whole flash device to find the current head after a power-up (the device is powered down rather frequently outside of my control) so logging can just continue where it left off.  I can just brute force through this walk and do it with ~4s as worst case scenario.

This got me thinking, are there any log structured filesystems that are catered to flash devices and microcontrollers?  JFFS and all the other well known Log Structured FSs I imagine would be a little heavy for a simple microcontroller (depends on the application of course).  To be more specific, I would like to know of any algorithms that are designed to specifically be a circular log with fast head seek time and/or any that are designed for a "traditional" filesystem on a flash device that can be run on a microcontroller.  Traditional in this sense being on-par with something like JFFS where there is a data structure that represents a collection of mutable random-access files in a hierarchical name space.


texts: Why do MoM capacitors need bulk connection?

texts: In recent am doing layout of crtmom in 180nm technology node. I found the bulk connection to MOM capacitor. I dont understand the why MOM cap need bulk connection or bulk terminal in design. usually MOM cap are mental on metal. so, why this bulk terminal is given??


texts: How to control a VFD display with Arduino?

texts:
I have a Samsung 170L40AA1 VFD display, but no controller. So I wondered if it is possible to use an Arduino to control it instead. I've found the code for controlling an Futaba NA202MD13AA, which I want to try, but I can't figure out how to connect the VFD to the Arduino.

Any pointers would be greatly appreciated!


texts: How to avoid noise/stray voltage in a cable which going to carry both AC and DC current?

texts:
The cable and it's capacitance discussed and answered in This question.

The schematic of my circuit:

simulate this circuit – Schematic created using CircuitLab

The load for the mosfet going to be a series of high wattage LEDs and for the AC voltage relays some AC motors etc...

The problem as discussed Here is the stray voltage ~60V on other wires when no load is connected, that stray voltage is causing noise and negative voltage on my DC mosfet. when mosfet is OFF there's a negative voltage -1.7V~ at the output of it.

How can i eliminate this "capacitance noise" from my circuit and of course other wires in the cable?

grounding unconnected wires is not practical in my case.


texts: Understanding calculations for baud rate fractional generator (STM32F4)

texts:
Trying to understand the USART_BRR oversampling calculation.
According to the reference manual, if we know what value we want in the BRR, we can deduce USART_DIV which contains the mantissa and the fraction part but i'm confused between the following examples shown. The upper one determines USARTDIV from USART_BRR while the other the opposite. Say, I want a baud rate of 921600 bps. Meaning, USARTDIV = 8MHz / (8*921600) = 1.085. So wouldn't I have to follow the bottom example given I know what USART_DIV I need to program?

But when I do the calculations, the math doesn't work out fine.

USARTDIV = 1.085
Frac = 0.085*8 = 0.68 = d0.7
Mantissa = 1 = 0xA
USART_BRR = 0xA7 = d(1.7)

According to the reference manual, it's 1.125.

MCU: STM32F4

Also, the easier way to determine whether 8x sampling results in higher baud rates than 16x is by using Clock / (samplingRate * baud rate). So for 8MHz clock, with 16x oversampling, we can't have a baud rate of 921600 cause of the following?

DIV = 8MHz / (16 * 92600)= 5.39 = ~5 (assume no fraction generator)
Baud = 8MHz / (16 * 5) = 0.1Mps

Whereas with 8x sampling:
DIV = 8e6/ (8 * 92600) = 10.7 = ~11
Baud = 8MHz / (8 * 11) = 90.909 Kbps