texts: Multiplies I / O reading with interruption in stm32f767zi

texts:
I am developing a board where 40 low I / O ports will be read, and I would like when I detect a low border to activate interruption for reading the port. in the documentation it says that "Up to 168 GPIOs can be connected to the 16 external interruption lines" connection is internal by software or external with components.

If it is externally I thought of a circuit like this.

Each input will have a resistor and two diodes, a resistor to limit the output current to not saturate the input port, D3 positive input protection diode, D4 diode to protect the action of another port connected to the same interruption port.

If I can read the 40 internal ports, disregard this circuit.
The "INx" signals for reading the 40 ports have an average of 10ms to 300 ms from each port and are random for each port and do not have a sequence.

My doubt is:

Can I read 40 internal ports with an interrupt?

If not, is the circuit I set up a good alternative internally?

Will the reading of the 40 ports have a loss for being between 10ms-300ms intervals for each port?


texts: Shielding and Ground Loops - RF panel jacks for GPS

texts:
I've been working on a design that requires me to pass an RF signal through a conductive panel.  I'm using SMA jacks for that purpose as they're readily available and also available in an isolated configuration like these.  The reason I'm using an isolated jack is to avoid a ground loop through the chassis and up the electronics assembly.  Here's an image of what I'm doing:

This image shows the return current path or ground (blue line), as if I were using a standard SMA panel jack where the shield would be electrically connected to the case like this.  So assuming I instead use an isolated jack, I'd remove the return path through the case. The problem now is that I've gotta get the assembly to be IP67 rated.  I cannot seem to find any isolated RF jacks that also offer any kind of ingress protection.

The GPS receiver provides a DC signal to the antenna external to the assembly for powering a LNA, so breaking the ground at the connector is out as I cannot have the return LNA current, or RF return for that matter, returning through the case and up the electronics as that would surely wreak chaos on my signals.

Does anyone have any suggestions?  I'm not an EMI/EMC expert but have been reading a bunch on the topic, though I still have a ways to go in developing an intuitive approach for nuanced situations like this one.  Thanks.


texts: What are the best methods to efficiently reduce the power in a 120v circuit?

texts:
Specifically, I am trying to find an efficient and cost effective method for minimizing required length of a Kanthal A1 heating wire element, but at the same time keeping the diameter large enough to allow for a relatively low surface load (w/cm^2) - to increase the service life of the element.

I would like to run the heating element off 120v-240v AC, with 200-400 watts. For 120v @ 200 Watts = 120^2/200 = 72 Ohms - After calculating, it appears I have a choice between too much wire for the available space, or too much surface load on a thin&shorter wire. Excess surface load is what causes the the wire to prematurely oxidize and burn up, or even melt.

For the purposes of surface load, can I effectively halve the load by placing a rectifying diode in series?
If yes, what would the best diode be for this application (assume the circuit would be continuously open, and there would be minimal heat dissipation for the diode beyond it's inherent rating.) How do you calculate the heat produced/dissipated by a rectifying Diode?
Would these work?  10A10

Are there better/additional ways to efficiently lower the power in the circuit? My understanding is that a resistor would dissipate power equal to it's reduction, so that's not an option. In case it influences the answer, any solution up to $50 parts cost would be worth considering, but under $10 is ideal.


texts: What kind of microphone is this and how do I use/bias it?

texts:
I am designing the mic input for a ham radio chip I bought, a DRA818V.

Someone gave me an old Kenwood ham radio mic and said I can use that mic for my circuit.  The mic element is shown below:

What kind of microphone is this and how can I use/bias it?

My LCR meter says it has 304 ohms of DC resistance.  It has 4.653 mH at 1 kHz of inductance.  I have an oscilloscope to use to complete my circuit.  The mic input of my chip, the DRA818V, is not well described, so I will have to experiment to see what the chip "likes".  I expect I will have to make a small signal amp from an NPN transistor to feed the "mic in" of my chip.

My main question is: What is this mic and how do I use it?  If I can set it up and see it on my oscilloscope, I can experiment if I need to amplify it or not?


texts: Where did this useful matrix decomposition come from for Nodal Analysis?

texts:
Background

The equations formed when finding the nodal voltages of a circuit can be expressed using nodal analysis as a square system matrix \$\mathbf{S}\$ (lets say \$m\times m\$ where \$m\$ is the number of nodes in a circuit) which describes the connections and values of the conductances that correspond to these connections, and can express a whole circuit as
$$
\mathbf{Sv} = \mathbf{i}
$$
where \$\mathbf{v}\$ is the collection of nodal voltages and \$\mathbf{i}\$ are the input current sources.

Super useful matrix decomposition

In this paper, I have seen this decomposed into (for a single impedance type, e.g. resistance)
$$
\mathbf{S} = \mathbf{N\ G\ N}^\mathrm{T}
$$
where \$\mathbf{N}\$ specifies the connections, and is an (EDIT) \$m \times n\$ incidence matrix which contain only values of 1, 0 and -1, and \$\mathbf{G}\$ is an \$n\times n\$ diagonal matrix containing the conductance values, and \$n\$ is the number of components.

This is a ridiculously useful property as it separates the conductances from the connections making them both easily readable. No matrix decompositions I've read up on have made it clear how this works or how you'd intuitively think to apply this decomposition. Could someone explain this?

Notes

The paper actually uses modified nodal analysis but this doesn't change the application as the decomposition is only used on the nodal aspects of the circuit, not the voltage sources.


texts: What is an on-chip interface and Why is it beneficial to have an on-chip I2C interface than polling

texts:
In the I2C Specification manual it's given
"When the device does not have such an interface, it must constantly monitor
the bus via software"

I am sorry but I don't understand what is meant by having the an On-chip interface on an micro controller or other peripheral.

And if it is not present then we have to poll the bus but according to me that is the only way , So what does an interface do what is an interface


texts: What does it mean exactly " averaging over eight symbol periods" when calculating RSS?

texts: When reading about RSSI, I usually found that RSSI is measured by averaging the signal reading over eight symbol periods, I could not understand what does it mean exactly and how RSSI is calculated by the transceiver. Please, could some one give me a good explanation about it.


texts:
It's my first attempt to design CMOS Differential amplifier in 0.35um technology using a cadence tool. I will explain my approach in deriving dimensions of MOSFET's used in it. Moreover, I have also attached my simulation picture for your reference.
I get help from the following reference for calculations:
https://medium.com/@vishnuanugrahith/designing-of-a-cmos-differential-amplifier-68d3d90baae4
Design Parameters:
GBW= 10M CL= 10pF, Vdd=5V
UnCox=190u A/V^2; UpCox=55u A/V^2;
Vtn=0.8V Vtp=-1V
Slew Rate(SR) :10V/uSec
Vcmax=4.5V ; Vcmin=1.5V (input common mode range)
Step 1 _ Calculating Id:
Id=SR*CL 10V/uSec * 10pF= 100uA
Step 2 - Calculating (W/L) for M3 and M4:
Vds1=Vmax-vthn=4.5-0.8=3.7V
Vds3=Vdd-Vds1=5-3.7=1.3V
Id3=Id/2=50uA
(W/L)= 2Id3/UpCoxvds3=1.075
Step 3 - Calculating (W/L) for M1 and M2:
gm1=GBW2pi*CL
= 10M23.14*10pF
=6.27*10^-4
Id1=Id/2
(W/L)=gm1^2 / 2Id1unCox
=20.75
Step 4 _ Calculating (W/L) for M5 and M6:
Vx=(Vmin-Vtn)-Vdsat1
Vdsat1= (2*Id1/UnCox * (W/L)1 )^1/2= 0.16
Vx=0.54
Id5=Id
(W/L) =2*Id5/UnCox * Vx^2= 3.6
Finally, transistor dimensions are:
(W/L)1,2 = 1.07u / 1u
(W/L)3,4 = 20.75u / 1u
(W/L)5,6 = 3.6u / 1u
Differential input Signal:
Freq= 1 Mhz; Amp= 500 mV; Sine DC level= 2V
Differential gain:
= gm2 (ron_n2 || ron_p4)
= 418.5u( 71.73K || 17.04K )
=5.7
1_ I am not getting the output signal according to my calculated gain? I am making mistake in my calculations?
2_ Could anyone comment on my design and mathematical calculations?
3- I am always struggling to find the unCox value of MOSFET. after searching in different threads in this and other forums. One way is to find it from betaeff=unCoxW/L. But unCox changes with changing W/L. So I am always doubtful regarding unCox value. Can anybody know the accurate method to find unCox value of MOSFET especially using Cadence?
Thanks.


texts: Basic h-bridge motor driver circuit for audio PWM waves with possible negative voltage

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I need to control a DC motor with the PWM audio waves coming out of the audio jack of a device. The device will send a positive PWM to drive the motor forward and a negative PWM signal for driving it backwards. The PWM signals can have an amplitude of 500mv max (positive or negative). I have a supply voltage of 5v also.

Can anyone please show me how to modify an H-Bridge or a similar circuit to make this work.


texts: Need to identify this pin receptacle and plug

texts:
I need to identify this pin and this plug so I can order more.

RESEARCH: I've pored over Molex.com, Allied Electronics, and here with no success. Please understand, I'm fairly new to electrical engineering and specifically these components. I'm not even sure what to call them. If I knew, it would make finding them a lot easier. I want to know, and I want to do this correctly, and that's why I'm here.

PIN: Critically, unlike nearly every other pin (female pin? pin receptacle?) I can find, this one is seated using the large notch closest to the end. Most I've found use opposing winglets that jut out to secure them within the plug housing, and that won't work here.

PLUG: The current plug has 12 ports in a rectangle layout. The new plugs need to have 4 ports in a square layout. As such, I destroyed one of the unneeded pins to see how it worked, thinking worst-case I can just cut these down to size. Note the style of the clip that secures the whole plug, as well as the small movable arm that holds the pin receptacle in place.

I need these parts to fix my car. It's parked until I figure this out. Also, I'd love to know the proper names for all of these components. Any help would be greatly appreciated.

Photos attached.

EDIT: This is going into a headlight ballast on an Audi. It was produced in 2001. Make and model won't help because these aftermarket headlights don't share any internal wiring with their OEM counterparts. The factory ballast was a 12-pin, and that style has been phased out, so now I need a 4-pin plug.

The original 12-pin plug bears the marking L JST. The pins are 1/2" long with a 1/16" opening.

Tons of photos of the pin, plug, and ballast here: https://imgur.com/a/utefuM3

EDIT 2: The "socket contact" as it's called appears to be SSF-21T-P1.4 from JST. That locking mechanism is called a housing lance. Still looking for the connector plug itself, which appears to have come from the JST HL series, which should work but the plug on the new ballast features two raised shafts on sockets 2 and 4 - see the imgur pics.


texts: Confused about this KVL equation (AC circuit)

texts:
I have the following circuit below, with part of the solution:

I need to find Z. I'm confused about the KVL equation below (fourth line):

If I understand correctly, they used loop analysis: with one loop around the entire circuit and one loop around the right mesh (Io).
So wont the currents Is and Io be added together when you reach the capacitor? Because aren't both loops are passing through that point?
So why isn't the KVL equation 2Is -j1(Io + Is) + Vo = 12∠0? Can you explain?

Thank you for your time.


texts:
The depletion region is formed at the junction due to diffusion which creates a thin width of negative ions on the p side and positive ions on the n side whose electric field restricts further diffusion of the free carriers from the n side to the p side.

A forward bias of this junction will allow the free carriers from the n side to overcome this electric field and recombine with the hoes on the p side.

However, this seems to me to be the same scenario as how the depletion region was formed in the first place. When the recombination occurs due to forward bias, then the p side forms even more negative ions and the n side forms even more positive ions which would then increase the electric field and therefore the forward bias applied (typically .7V) would not be sufficient anymore and no more current would flow. What am I understanding incorrectly?


texts: Is there any hope for this power supply to work on 220V rather than 110V?

texts:
I stupidly moved my laser printer with me overseas without checking whether it would take 220V. I assumed it would be like my desktop computer and accept both.

Anyway, here I am with a 110V printer in a 220V country. The label says 110V 50/60Hz.

I've opened the printer to look at the power supply, and I also found the service manual.

On the board, there is a 250V fuse, a 125V fuse, and a smaller fuse. According to the schematics, the AC input first goes through the 250V F1 fuse, then the 125V F2 fuse, then the smaller one (F3).

There is also a somewhat large capacitor that says 200V 270uF.

Do you think it's possible this power supply would accept 220V without modification, but it's not labeled as such for whatever reason? I think Sony did that on the PlayStation for instance to try and curb the grey market.

Here are pictures of the board, and the service manual.

service manual (relevant pages: 165, 167, 168)


texts: ISO Example Home HVAC Control Schematics and Circuit Design Info

texts:
I am currently interested in determining how a home thermostat controls a home HVAC unit. I have run into plenty of schematics that can control a HVAC window unit, walk in freezer, water temperature, etc. However, using a circuit like those on a unit as expensive as a HVAC unit is just nuts as far as I am concerned...plus it doesn't take care of all possible operations.

The question I seek an answer for: How do you build a complete home thermostat. A device that protects and is built to ensure no damage is done to the HVAC unit. I am planning on buying a cheap $10-20 thermostat just to tear it apart and study the board in detailin a few weeks if I cannot find any other answers.

My current home HVAC unit uses a 4 Wire Heat/Cool setup which is referenced on page 17 (10 on adobe reader) of this thermostat installation manual: http://www.ritetemp-thermostats.com/60XX/images/6022_installation_guide.pdf

Connections are as follows:
W - Heater Control Line
Y - Cooler Compressor
RH - Heater/Cooler Power
G - Fan Control
C - Optional Thermostat Power (which I have)

What kind of control does this device use? Is it 1-wire? Where is the GND connection? In addition to this wire diagram, the unit also provides C which powers the thermostat itself ensuring no batteries are required. I wish I could tear this unit apart but do not have another thermostat to put in its place until I get paid.

If you can help me/point me in the right direction; I would be much appreciative.


texts:
I am working on a project that will ignite a match on command using Arduino. My external power supply, when connected to a thin strand of wire, heats up a wire causing ignition. To control this I want to use an NPN transistor, with my external power supply connected to the emitter and collector, and when I want to heat the wire I will supply power to the base of the transistor, allowing the circuit to close and the wire should heat up.

My problem is that there doesn't seem to be the same current flow through the wire when the transistor is in place and power is supplied to the base, compared to when I remove the transistor from the circuit. In this closed circuit (with the transistor in place), the wire doesn't heat up, which confuses me because I thought that when power is supplied to the base, it is as if there is a free flow between the emitter and collector. I measured the voltage when power is applied to the base of the transistor, and this voltage is identical to the normal voltage of the power supply (without the transistor), which makes me think somehow the current flow is being reduced.

Is it possible that the transistor is reducing the current flow when power is applied to the base? Why is this? Any suggestions to fix this?

My external power supply is a 3.7v 500mAh battery, and the power to the base of the transistor is about 40mA. The transistor I am using is NPN transisto

simulate this circuit – Schematic created using CircuitLab

r PN2222.

Thanks in advance.


texts: RS-485 shield and ground wiring practice

texts:
After some reading I was convinced that I have three options:

The best: connect A and B lines to a twisted pair, signal ground (SG) line to therd wire in the cable (or to a second twisted pair) and connect cable shield to protection ground (PG) only at one side (important!!!) of the network.
If there is no sheld: I should connect A and B to a twisted pair and SG to therd wire.
If there is no third wire: I should connect A and B to a twisted pair and SG to shiled on either sides.

I'd avoid using earth as third wire (Signal Ground) or skipping SG connection.

Is there anything I left behind?


texts: Why doesn't this circuit simulation work?

texts:
I am trying to build a circuit using only encoders and decoders. This circuit  will output the 1’s complement of 3 bit number. (For example: If I give it 010 it will give output 101.)
I used a 741LS138 3 to 8 decoder and an 8 to 3 encoder (the 8 to 3 encoder is working fine.)
The problem is that it does not show the desired output.
When I try to provide input the output always stays 0.
I have made a truth table. I cannot figure it out what is wrong with it.
The circuit that I made:

Truth table:

Here is the schematic of the 8 to 3 encoder which I built:


texts: What is the term for a photo sensor that takes low-resolution, black-and white, closeup images?

texts:
For work I used to have to read and log 7-segment LCD numbers off this tiny (3cm x 1cm) screen tens of times per day. Now I have a webcam setup that reads it for me and does some OCR to automatically log the numbers. However the current setup stands out, and I want to make something more inconspicuous.

My idea is to replace the webcam with a close-up sensor that can be mounted less than a centimeter away from the LCD screen. Then I can put it all in a tiny enclosure with an LED, and make it look like a little magic matchbox.

The problem is I have no idea what this kind of component would be called. I've searched for lots of things like "low resolution photo sensor" but found nothing remotely like what I'm looking for. How can I find something like this? I am willing to do electronic component assembly, programming, pretty much anything necessary to keep me from being forced to read those damn numbers again.


texts:
As many others before, I'm aiming to build my own simple CC CV lab bench PSU based on the LM317 regulator. Now, I've defined most of the circuitry, but I'm stuck with a particular design choice regarding the Adj pin of the LM317.
Since I wanted to use an Op Amp to drive the Adj pin, I wanted to know what are the pros and cons when:

using the output voltage of the Op Amp at the Adj pin as negative feedback
vs.

using the output-voltage regulated by the LM317 as negative feedback.

In my mind the latter would be able to account for the voltage reference fluctuations of the LM317, but I assume that on the other hand it might be somehow unstable. If this is the case, how can I compensate for these instabilities?
Added the schematic for the Adjust-Pin driven LM317 circuit


texts:
What tradeoffs should I consider when deciding to use an SPI or I2C interface?

This accelerometer/gyro breakout board is available in two models, one for each interface.  Would either one be easier to integrate into an Arduino project?

http://www.sparkfun.com/products/11028


texts: Power transformer secondary 250-0-250, 3.15-0-3.15 3.15-0-3.15. How do I connect to circuit board to have 6.3vac?

texts: Power transformer secondary 250v-0-250v,  3.15-0-3.15, 3.15-0-3.13.  To get 6.3v how do I connect the taps?


texts: Do dead CFL or LED light bulbs consume power and is it safe to leave them mounted?

texts:
Do burned-out CFL or LED  light bulbs consume power when the switch is on?
 Is it safer to keep them in their sockets, removed or slightly unscrewed so the bottom center contact isn't touching?

I replaced some dead CFLs with brighter LEDs with roughly the same wattage and thought keeping the other old bulbs in their chandeliers will provide coverage preventing short circuit if a grasshopper or a nail choose to go inside one of these roof facing sockets and the chandeliers look better when not missing some bulbs.


texts:
I am looking for an aluminum capacitor that doesn't exist. It has to be 600uF, 450V, but fit to height of 30-35mm and endure 10000 hours. Would be nice, if it could be rectangular. Ah, and cheap.

So the question is, is there other capacitor technology available for such requirements?


texts: arduino-tiny: change TIMER_TO_USE_FOR_MILLIS from sketch

texts:
In the arduino-tiny core, is it possible to change TIMER_TO_USE_FOR_MILLIS in the sketch itself? I want to be able to leave my arduino-tiny install stock but swap the timers just for one sketch.

I've obviously tried "#define TIMER_TO_USE_FOR_MILLIS 0" but to no effect.


texts:
I am building a project for a consumer. It involves switching  about 20 fluorescent tubes. I don't want something to go wrong with such heavy switching. So, I was researching about the relays and looking about their specs. After some search I found out that specs on most of the cheap Chinese relays are misleading and incorrect.There are many videos online which show that the relays (SSD specifically) which were rated for higher values, had even lower rated components inside them. Also, the specifications provided by different companies relies on different testing conditions. Hence it may not be reasonable to compare two relays just on the basis of their specs.

How can I cleverly search for the correct specifications and check if the information provided on a relay is reliable? How much can I trust the rated values?


texts: Circuit works on battery but not on power supply. Any ideas why?

texts:
simulate this circuit – Schematic created using CircuitLab

I have built a wooden clock that is powered by an electromagnetically driven pendulum.  Circuit given above was originally developed by a chap called Dick Bipes.  In principle it works by a magnet attached to the end of a pendulum passing over a coil which detects the passing magnet and after a short delay, sends power to the coil to repel the magnet and keep the pendulum moving.  An MSP430 processor is used to do some clever calculations and keep the timing accurate.

The circuit works fine when powered by 6V battery but ceases to work properly when I replace the battery with one of those plug in variable voltage power supplies!  The processor doesn't initialise and I get no output to the coil.  I have checked voltages and everything appears to be fine - correct voltage to processor, etc.

However, when using the power supply, if I connect the negative rail from my breadboard to Ground on my Launchpad which is connected to my laptop via USB and the laptop is plugged into the mains, everything springs to life!  (Doesn't happen unless laptop is plugged into mains!)

So sounds like some sort of grounding issue but why does it work OK on battery and not power supply?  (Have checked power supply and it is providing the expected 6V).  Any thoughts or ideas on how I can resolve this frustrating issue?


texts: What can I do on the bench to determine if a power supply does or does not add back a PFC (Power Factor Correction)?

texts:
I'm given a AC to DC power supply with only the inputs and output specified.  It was probably made after 2000, and the ENERGY STAR program mandate to add PFC correction to power supplies may or may not have been implemented.

Some of these are AC power bricks (e.g. laptops), others are PC case supplies.

We've a bench to set the supply on which has multimeters, an oscilloscope, plus parts (resistors, caps, chokes) to rig up some loads for the supply.

What can I do on the bench to determine if the supply probably does/does not add back a PFC?

I need to avoid hooking a newer PFC supply to an older/cheaper non-sine wave UPS (Uninterruptible Power Supply).  A stepped wave form from a UPS on battery can blow the PFC supplies.


texts: Small, cheap, and simple driver for 16 RGB LEDs

texts:
I am working on a board design that will put 16 RGB LEDs in a circle around a rotary encoder. I want this setup to be simple so that I can run it from any micro with limited software (ie. built in PWM control, no tedious management necessary on the micro). I also want it to be relatively compact so that this board will not take up much space. I would also like it to be as cheap as possible in medium quantities. These 3 criteria are likely in competition, but I would like to know what others would suggest.

I have considered shift registers. These might be cheap and somewhat compact, but they would require the attached micro to spend a lot of time managing the LEDs to do any sort of colour blending.

I have also looked at some PWM LED drivers. The best one I have found so far is a 16 channel chip, so I would need three to drive all my LEDs. It would be simple to use, but the space and cost would not be great.

Another option might be to use some sort of FPGA or dedicated micro with lots of IO to control the LEDs. I'm not sure if the power needed by the LEDs would be too much, though.

Is there some option I am missing that would fit this target usage? I am open to a solution with slightly more or less LEDs, but I would not want any less than 12.

Edit: For reference, I am basically trying to replicate this board or this + this but with RGB capability, including colour blending. If the ring has to be a bit larger, that is ok to some extent. I would still like to be able to put a couple boards next to each other in a single project without too much spacing.


texts: Snubberless TRIAC not turning on in negative cycle

texts:
I have a simple circuit with a MOC and Snubberless TRIAC.

I am using the ST Snubberless Library for my simulation.

I cannot understand why the TRIAC does not turn on in the negative half cycle, even though there is a negative gate current and negative terminal voltage.

Perhaps I am burnt out of thinking about this problem for too long, a second eye would be appreciated. The model file itself could be the problem, but again, I am not sure.

The green graph is the gate current.
The orange graph is the voltage across the load.
The cyan graph is the voltage over MT2 and MT1 (VAC and Vload).


texts: Is it feasible to chain high voltage dc boost converters together to get bipolar (dual) output rails?

texts:
I have two Recom R24-150B dc-dc converters (24V in, adjustable up to 220V out) and I want to have +/-220V output rails. The converters need a resistor between the - (COM) output and their adjust port in order to set the output voltage. This acts to regulate the output.

According to the data sheet it is ok to tie the outputs of these converters together to obtain higher voltages because they're isolated, as long as some capacitors are attached across the outputs of each unit to prevent beats appearing between the switching frequencies of the two units.

I tied two together and attached the filtering capacitors. I grounded the middle to create the bipolar output rails, and this produces the desired dc voltages on each rail, +220V and -220V. However I am seeing quite a lot of noise with my oscilloscope around 1 MHz on the load attached between the two HV rails, around 200-300 mV peak-to-peak. The switching frequencies should be around 200 kHz so I guess this is some higher harmonic content. This noise appears to be on the ground rail between the two converters because the noise on each of the HV rails is smaller and in phase. The individual output ripple from each converter is less than 100 mV peak-to-peak so clearly something is ringing up and increasing the output noise.

Is there some reason why bridging two converters together like this to form differential outputs is a bad idea? Or is there some additional filtering required somewhere?


texts:
How can I get the inaccuracy associated with the GPS data. For example when I read lat, lon, speed, heading data from a GPS receiver, how can I get an approximation on the inaccuracy that is associated with each of these data. For example the x position might be +-10m accurate or the speed might be +-3m/s accurate.

Can I obtain these inaccuracy from the GPS chip datasheet?


texts: Are there gaps in the 2% resistor standard values?

texts:
I was reading the Wikipedia entry for E-series resistor values, and I decided to graph the values on a log plot. The plot shows the values nearly evenly spaced, which makes sense because adjacent values are supposed to be related approximately by the factor where N is the resistor series (E6, E12,...,E192).

If I then plot the tolerance range for each value in the E6,E12, E24 ranges, I see overlap for each standard resistor value with the adjacent value – this makes sense because every resistor made can then be used. Here is my plot, which is crude but makes the point – note that I zoomed in a bit, so all values are not shown.

However, if you plot the range of values for the E48, E96, and E192 ranges, I see small gaps. This means that every resistor made may not fall into a standard 2% tolerance value. I show my plot for the E48 resistor series below. I zoomed in quite a bit to make things a bit clearer.

I can also demonstrate that the gaps exist using algebra, but I thought the charts illustrate the issue better.

Are there really gaps in the 2% standard resistor values?


texts: Determination detection of direction with 2 optic sensors which are on opposite sides of disc

texts:
I would like to ask you is it possible to detect the direction of rotation with 2 optic sensors which are on opposite sides of disc? In the disc is small hole, when the part with hole goes through the optic sensor the signal from optic sensor is "1" otherwise is signal "0". I am thinking about method store order of 4 values (10,00,01,00) but it seems that it will not work.
Thanks in advance


texts: Use SDIO pheripheral for quad SPI flash memory

texts:
I am currently doing a project using the STM32F103 micro-controller. The project requires external flash memory to store images and data for later showing on LCD.

The problem I have is that I want to see if I can use the SDIO peripheral on the micro-controller in order to control a Quad SPI flash memory.

Can you use sdio interface with a quad spi flash?


texts: MOSFET W/L ratio limits: what's (un)reasonable?

texts:
The answer to this question is probably process-dependent, but what are the limits of the W/L (gate width/gate length) ratio for MOSFETs?

I don't know what is in the realm of the insane. I saw a design example that ended up with transistors sized at 222/0.4 µm, which is a W/L of 555. That seems extremely high to me, but I have no professional design experience, only academic.


texts: Decoupling Capacitors on each VDD pin on a tiny 36/49 ball WLCSP/µBGA chip really necessary?

texts:
I've searched this and many other sources on Info on decoupling capacitor placement, but couldn't find any info specific enough to my current problem.

I'm currently doing a PCB Layout for a tiny, ultra-fine-pitch WLCSP microcontroller. It's 3x3mm and has 49 Balls (7x7) at 0.4mm pitch, and I'm looking at another with 36 balls (2.1x1.9mm with 0.35mm pitch).
There are a couple VDD and VSS pin pairs, and unfortunately not all on the outer balls. I've tried placing all the recommended decoupling caps as close as possible to the pin-pairs, and connecting them with the shortest traces possible, as everyone recommends. However, I'm running into routing problems, and have realized that trying to keep one Capacitor on each pair of supply pins actually leads to much longer traces than if I'd just connect some of the pins to each other, so some of the supply pins would share a single capacitor.

I get that each pair of supply pins ideally should have its own capacitor. I'm not 100% sure of all the reasons why, but my understanding is it's mainly for guaranteeing shortest traces-> lowest impendance, and therefore best (local) "stabilization" of the supply voltage. And of course for seperating Analog from Digital, but since my circuit is digital only, that's not MY worry at the moment.

Now I'm wondering if this still holds true for such tiny devices, where I could, for example place a single capacitor on the bottom side, right under my component, and have all my Vdd and GND traces reach it with a single via and less than 1mm trace.
1) Why would I want to put 2 or three there?
2) Would it be better or worse if there is absolutely no space there for say the third cap anymore, and my next best option would be to place the third Capacitor next to the chip on the top layer, but require two vias and 3mm trace length to reach it, compared to a single via and 1mm trace the first or second Capacitor already under the PCB?

The supplying LDO with a bigger Capacitor (2.2 or 4.7uF will be maybe 5mm further away...)

Thanks for any helpful Info.


texts: How can I model this linear power system in MATLAB?

texts:
For my power system, let us suppose it has the following dynamic model: \$\ x ' = f(x,u)\$.

This dynamic model consists of four first order differential equations (see below).

Then, I linearized my system using Newton-Raphson method. My new linear system will be:

\$\ \Delta  x ' = A \Delta x + B u +\$ disturbance

Where:

\$\ x \$  is the state vector that  that contains 4 first order differential equations: (the power angle δ , the angular speed of the rotor ω, the generated voltage in the quadrature axis of the generator eq', and the field voltage of the generator in the direct axis  \$\ E_d\$ ). a.k.a.: \$\ \Delta  x = [\Delta  \delta, \Delta  \omega. \Delta e_q' , \Delta E_d ] ^T \$
\$\ u \$ is the control part. Let us make it zero for now
Let us assume that the disturbance in the power input of the generator is just 30% (0.3 pu) for only 1 second.

"A" is a 4 x 4 matrix. Let us say:

$$ A= \begin{bmatrix}1 & 2 & 3 &4\\5 & 6 &7 &8 \\9 & 1 & 2 & 3\\4 & 5 & 6 & 7 \end{bmatrix} $$

The question is:

How can I model the system shown above using MATLAB? I want to plot the four state variables, but I don't know where to begin

Is there any specific code that will help me to simulate this system.


texts: Intel hex file to UU-encode format for LPC2148

texts:
I'm writing the application for OSX which needs to send a new program (compiled lpc code) via Wifi to microcontroller and there i will use built in In-Application-Programming interface to program flash memory. Similar thing i have done in a past for Atmel AVR where i sent .hex file and write it to flash memory.

I saw that NXP LPC is using some UU-encode format (3 binary bytes to 4 ascii bytes) and little different packaging of the data. What i dont know is how do i get this UU-encode file? Do i need to make converter for HEX2UUE?

I'm using Keil uVision compiler. Any setting there to produce it ?


texts: Why a DC coupled sine input signal will make my biased emitter follower looks like unbiased in LTspice?

texts: I'm trying to simulate a biased emitter follower in LTspice. The dc operating point seems to be wrong once I used a DC coupled sine input signal(zero offset, 5V amplitude, 60Hz), it is almost 0V at emitter follower's output. Once I place a capacitor between sine input and voltage divider(make the input signal ac coupled) the dc operating point makes sense, it is about 7.5V, half the supply voltage. I think there is no difference for a zero offset sine input signal to be ac or dc coupled. So why a DC coupled sine input signal will make my biased emitter follower looks like unbiased in LTspice? Is it just simulation behavior or in real life it actually behaves like this?


texts: How to select components for crowbar circuit?

texts:
I need to make a protection circuit for over voltages (protect from more than 5V, protect from 6V to 30V) and current(protect from more than 5A)

Could you please suggest components for following circuit or tell me the things I should consider when select SCR ?

Please suggest me ZD1, Q1, C1, C2, R1 values for above specifications.

Are there any IC with above spec which included crowbar circuit ?


texts: How can I calculate how much my desktop PC costs to run for an hour?

texts:
I was torn on whether to post this to here or Math.SE, so feel free to move it as appropriate.
I recently got hold of a power usage monitor in order to calculate how much my PC costs to run a given task for an hour, but before I do so, I want to find out how to do the calculation "on paper", and use the power usage monitor to determine just how accurate it is.
That being said, this question essentially has two parts to it.
Firstly, the PSU on my PC has a max output of 550W, but I've been advised that it's likely to use much less than that even when running. To that end, is CPU usage in the Windows Task Manager a reliable enough metric to use for this purpose?
In other words, if my CPU is consistently showing 25% (or 100%) of usage consistently for carrying out a specific task, can I assume that 25% (or 100%) of 550W is a good starting point for the sake of calculating cost?
Secondly, what is the calculation to determine the cost of running a PC for a single hour?
I have somewhere to start in that I know that the formula:
Power usage (in watts) * hours of usage / 1000 * cost per kWh
...can be used to determine the cost of running a PC for the given amount of hours.
Knowing that, is finding out the cost for a single hour as simple as omitting the hours of usage from the formula, like so:
Power usage (in watts) / 1000 * cost per kWh
...or is it more complicated than that?
These might seem stupid questions, but my maths skills especially are really lacking, and I've been frustrating myself over the last few days trying to work it out, so I'd appreciate the help. Thanks.


texts: Pulse transformer reset current simulation in LTspice

texts:
I am simulating the pulse transformer in LT spice to see how core gets reset using the diode D1.

Diode D1 current (Id1 : red colour) is in pulsating form as shown in the image below.

But the magnetizing current (Il1 : blue colour) keeps on adding by each pulse and never returns to zero during off time of the pulse.

Transformer is not saturating since I can see clearly the input pulse on the secondary side without any distortion.

What could be the reason that magnetizing current is building though I have done reset arrangement?

thanks in advance.


texts: What are the different grounds on a PCB?

texts:
I am working with boost converters recently. I have problem which you can find here.
After going through the datasheet several times I encountered the special focus on the ground plane. It talks about different ground nodes. I have no idea what it means. I would be grateful if someone can point out what is the best practice as well. Any suggestions would be appreciated.

My revised layout:

Circuit diagram:

C1 ceramic 10% 2.2uf
C2 ceramic 10% 4.7uf
L1 1uh 1206 package


texts: Effect on mAh of connecting 2 batteries in series

texts: Two batteries, each at 1000 mAh let's say, connecting them in series will not result in a 2000mAh capacity, right?


texts: LiFePO4 lithium iron-phosphate cells - OK to dip?

texts:
I want to try epoxy-dipping a PCB with an 18650-sized LiFePO4 cell. This is for a low-power application and is slow-charged, so thermal is a non-issue. Before doing anything unforeseen dangerous, is this cell type "sealed" or otherwise safe to dip?

From my understanding, LiPo's and other lithium types can be rather volatile, but iron-phosphates are far safer. Thanks!


texts: In this schematic, where is the depleted layer once voltage is applied to the the sensor?

texts:
In the following schematic from
https://cds.cern.ch/record/2717863/files/CERN-THESIS-2019-340.pdf
the sensor is the top part, the readout electronic is the bottom.
Once we have applied an electric voltage, where is the depleted layer ?
(Is it in region of n-silicon and p+ ? Is it in region of (n+ of middle, n-silicon) and p+ ?)


texts: Capacitance of circular parallel plate capacitors

texts:
I've been trying to solve this question for a while now , but I can't seem to get to the written solution.

Question : Calculate the capacitance of a parallel capacitor having two identical conductor discs (radius R , revolution axis Oz) seperated by a dielectric of radius R, thickness d , and permittivity ϵ.

Attempt to solve

Using Laplace's equation:

∇^{2}V = 0

Since V only depends on z , V = Az+B

Assuming that V(0) = 0 --> B = 0

V(d) = V0 --> A = V0/d

Then We get V = (V0/d)z

Using Conductor-Dielectric Boundary Conditions:

Dn = ρs = ϵE , where ρs is the surface charge density.

Q=∫ρs . ds =  ∫ϵE.ds

E = -grad(v) = -V0/d

then we get  Q = (-ϵV0πR^2)/d

C = Q/v0 , hence C = (ϵπR^2)/d

However this differs from the solution manual which is : C = (ϵπR^2)/(d+R - √(R^2+d^2))

Thanks in advance.


texts: Direction of the main beam of an antenna

texts:
How can I find direction of the main beam of an antenna if antenna has radiation intensity as following?
$$U=[\dfrac{sin(5\pi cos\theta)}{10sin(\pi cos(\theta/2))}]^2$$
Where
$$0<\theta<\pi$$
My first trial is to find the places where derivatives equal to zero. But the results also give places of the nulls. So, how should I distinguish themain beam between the all nulls (zeros) and sidelobe peaks (local maximas)?


texts: Why is lenz law not applied in this crcuit analysis

texts:
So in this circuit, initially the current and voltage is 0. At t = 0 the voltage snaps to V.

Now my analysis is:
According to Lenz Law the voltage developed will be in the direction as specified in red markings in the image because a back emf will be developed. So the KVL equation would be:

\$-v_S + i_L R - v_L = 0\$

Applying Faraday's Law we get:

\$-v_S + i_L R - L \frac{di_L}{dt} = 0\$

Now I have taken \$v_L\$ to be the magnitude of the voltage, because since we indicated the direction in the circuit.

But the textbook has this equation, obviously I am wrong but I cannot see where my reasoning is wrong.


texts: Can I connect RFID tag to a microprocessor?

texts: Is it possible to connect an passive RFID tag to a microprocessor and functions as a receiver? I am new in this,so I need abit of advice on how to do. I've heard alot that it is possible but there is no methods on how.Anyway,I want the tag to function as a receiver and receives data given from devices like NFC-enabled smartphones,and transmit the data to the microprocessor (I'm using Attiny45) and activates a certain circuit.Btw,I'm using passive RFID that is the same used inside passive RFID cards (due to its frequency,947 MHz).


texts:
I am trying to design a Class A Audio Amplifier with the following specs:

9V DC Power Supply, Maximum withdrawn current 15mA
Used with a Low Impedance (8 Ohm) Speaker
Provide a minimum variable gain of 10
Can work with frequencies from 20 Hz - 5 kHz
Input signal is 0.2 V(peak to peak)

I tried several designs and I faced the following problems:

Is it possible to actually drive that low impedance load with only 15mA, given this input signal? All the designs I did drew about 500mA from the DC Supply
The signal always had some sort of clipping.
I had some problems choosing coupling capacitors for the design.
While choosing a Q point for each transistor, I had some problems figuring out which Ic should I assume to start working with

The design is mainly built on a common emitter stage then a common collector stage to act as a buffer. I will attach two design concepts I tried (none of which actually worked).

I would like to know if one can clarify the correct procedure of calculating the correct Q point, and then walk me quickly through the steps of making the required calculations of designing such an amplifier.

EDIT
So I have been working for some time on this, and I reached this final design, but we neglected that 15mA current limitation.

I am not sure how this performs on real life, I have just been testing that on simulators.


texts:
I am interested in hearing the "noise" electronics make thru EMFs.  I have a coil of wire, and an audio cable with dual 3.5mm jacks (one on both ends).  This cable supports stereo audio (TRS), so how would I connect this coil?  The coil has two ends.  Thanks for your help!

P.S. No other topic I found had precisely this issue, most of them were cutting their cords.


texts: Infinite impedance at resonance in parallel LC circuit ? does that mean it is not usable?

texts:
In a parallel (tank) LC circuit, this means infinite impedance at resonance. In a series LC circuit, it means zero impedance at resonance: What does that mean?

Does this infinite impedance at resonance in the parallel LC circuit means it is not feasible to use at resonance frequency ? and vice versa for the serial circuit, does it's performance better than serial circuit at resonance ?


texts: Investigating the cause of the drift for this system

texts:
A force-torque transducer data acquisition system is shown below:

As shown in the above illustration, basically a six-axis transducer is powered and amplified by an interface electronics and then the differential ended output voltages are coupled to a data acquisition hardware to be processes by a PC.

Some civil/mechanical engineers mount a model on the top of the transducer and apply wind to analyse vibrations. They rotate the model and apply wind to measure vibrations for different angles.

Recently they have been telling that, when they take offset(no wind condition) during the measurements they observe drift. I first thought it could be the excitation voltage but then I know the voltage inside the electronic interface is very stable. The drift is observed during an offset measurement. I also have been told that the temperature is not changing during the 1 minute offset. So drift most probably is not due to the temperature of power supply.

In the manual here there is a section about drift and hysteresis:

I have never heard something called "mechanical coupling" and in this case I don't understand what they mean by:

  Make sure the tool and tool adapter plate and the transducer body are
  isolated from each other

I don't know the amount of drift at the moment and for now I suggested them to wait for the drift to settle and then take measurements. But soon I have to go to investigate about these.

What can be done as a procedure to verify the root cause of the drift in this case? And what is meant  by "mechanical coupling" and isolation in the manual?


texts: Will using an SSR on the secondary side of a transformer lead to heating due to harmonics?

texts:
I have a resistive heater with a resistance of 18 Ohms. The heater is mounted on a job which has a thermocouple mounted on it. I need to use a SSR based controller to control the temperature measured by the T/C. As per my calculation I need to produce 1500 W. I have at my disposal a 230 V, 50 Hz power source, rated at 16A.

I plan to use an isolation transformer to drop the 230V to 165V with the SSR and the heater mounted on the secondary side.

My question: An SSR will generate a number of harmonics due to "chopping" of the sine wave. Question is will these harmonics lead to heat generation in the secondary winding of the transformer?


texts:
I am looking into LVDS and I see the terms Vpp and Vdiff being used. I understand how LVDS works but the terminology is a little bit confusing. For the below picture we can see Vcm = 1.2V and the maximum and minimum voltage swings by 1.35V and 1.05V.
I assume that Vdiff = 1.35V - 1.05V = 0.3V and Vpp = 2 * Vdiff = 0.6V. Is that right?
And why do we have Vdiff and Vpp. For what do we need to know Vpp?

Source: https://www.allaboutcircuits.com/technical-articles/lvds-high-speed-low-power-robust-data-transfer/
In the example below we see a LVDS circuit. There is a 350mV voltage drop across the resistor. Is this value the Vpp or Vdiff value?

Source: Texas Instruments (https://training.ti.com/lvds-overview)


texts: Laplace transform and the idea of frequency domain analysis

texts:
I have studied control theory in depth in my undergrad and still continue to use it on many occasions in my PhD work, but i still don't fully understand why we call Laplace transformation of system a "frequency domain analysis".

I know that Laplace transform is a mathematical tool to move from the time domain to the s-domaine to substitute differential equations to algebraic equations which makes the mathematical analysis a lot easier. And of course S-domaine is linked to the frequency domain with the relation S= alpha + JW.

But take for example the Laplace transform of the step function u(t) = 1 ; t>=0 , which is 1/s, the step function has a frequency of 0 and i don't see how 1/s represent a "frequency domain equivalent of the function".

what makes this more incomprehensible to me the fact that based on the S-plane analysis of the system, we draw bode plots which shows gain and phase shift based on the frequency of the input !!

My question is kind of an attempt to fully understand the mathematical idea behind the Laplace transform and how it relates to the actual physical properties of the control systems and the signals that drives them and i appreciate anybody sharing his/her prospective.
Thanks


texts:
I'm in need of a little guidance in a project I'm working on.

Basically, I'll be using two arduinos:

The first one will have:

1 RF Link Receiver (linke here: https://www.sparkfun.com/products/10532)
1 Ethernet Shield

The Second one will have

1 RF Link Transmitter (linke here: https://www.sparkfun.com/products/10534)
1 RHT03 Humidity and Temperature Sensor

As you can probably figure, what I want to do is read some data from the sensor in the second arduino, transmit it over RF, receive it and send it to a server in the web.

I'm having some trouble deciding what approach to take in sending via Web and receiving the data over RF. I'll need to constatly listen to the receiver, and If I receive a message then send it.
I thought about coding a Linked List, and "storing" the values of the sensed data, and then send a http request for each object in the list until it  is empty.
But what if I receive another read from the sensor while I'm sending the message? What way would be best to send the data over the arduino Ethernet Shield and still be able to get the messages from the RF receiver?

I thought about interrupts, but I have no idea how it would behave while reading the response of the HTML request, as most examples use millis() and delay functions.


texts: Singular interval condition for Multi input in Optimal control

texts:
The definition of singulr interval is shown in Figure.

I've struggled with this problem.

I think the solution of this prob
is "because if the E_j matrix is not singular, it means the System is controllable, so it doesn't have singular interval...
But I want to know the details of the solution,"the precise answer" of this problem.
Please help me to escape this prob:(
Thanks in advance


texts: What is the reason the output signal I obtained from full-wave bridge rectifier has changing amplitude?

texts:
I observed the output signal of full-wave bridge rectifier sending sine wave and square wave for an experiment. In both of the output signals it is clear that each cycle shows one of the two different maximum voltage values and I have no idea why this happens. The bridge rectifier was built with 4 x 1N 4001 diodes which supposed to be identical and a 100 ohm resistor. The output signal across the resistor was observed. The schematic of the circuit is this.

simulate this circuit – Schematic created using CircuitLab
To be more clear I will add the input and output signal images.
These are the input signals displayed in oscilloscope.

And these are the output signals displayed in the oscilloscope

The experiment was conducted in a freshman physics lab.


texts: Building a menu and scheduler for a thermostat (rotary encoder for input, LCD screen)

texts:
I'm building an advanced thermostat on an arduino with the following goals:

Use a rotary encoder (with pushbutton) as the only input device
Use LCD display (standard 16x2)
Use a real time clock
Ability to schedule temperature changes
Ability to 'ramp' between changes (ex: start at 45 degF, end at 50degF 3 days later with a linear increase between start and end date)

I have much of this project finished but where I've stalled out is building a 'scheduler' function and finding a good menu method. Can someone please suggest a function that would work as a scheduler and give some examples of a menu that might work well with this project?


texts: Easiest way to switch device remotely with low power

texts:
I have a simple RTC module with alarm function - think alarm clock with no display. Most alarm clocks run all year on AA battery power.
I’m looking for an easy way to turn the alarm off remotely from another room.
As I understand, adding an Arduino or  Pi would change the battery life from months/years to days, a couple of weeks at best.
There are some popular zig bee/Bluetooth boards but they require more logic.
I only need a wireless relay. IR will not work through the wall. There seem to be some BT relays and timers but they are large and designed for mains powered appliances.
Can anyone recommend a solution?


texts: Hacking a four load sensor based personal weighing scale

texts:
I am trying to hack a personal weighing scale.I had taken help of this tutorial but the language used in this is not very easy to understand due to the non-standard naming used for load sensor wires, but its a good tutorial.
I had also looked at this tutorial to have a good understanding of adding a strain gauge in whetstone bridge in order to measure small change in resistance.

Also the amplifier used in the tutorial is not easily available in India i.e. INA125.

My question is , is there any alternative for the amplifier INA125.

Also i had read certain other tutorials for adding load sensor to the INA125 , but wasn't able to figure out exactly how to do it?

When i looked at this tutorial, i find that load sensor has to be added in place of resistors in Wheatstone bridge, but every load sensor has 3 wires, now which 2 wires has to be added in Wheatstone bridge,in order to make a full bridge circuit like this
.
I had even looked at a similar question but didn't get the answer.

I am enclosing images of the load sensor and weighing machine which i am using.My main aim is to read the load sensor readings with Arduino for a different project.

I had came up with a possible interface of the 4 load sensors to INA125 amplifier, can some body verify this?Below is the image.

In this A and B will be connected to the pin no 6 and 7 i.e. VIn + and VIn -


texts: Interfacing 2 accelerometers through I2C

texts: I am looking at designing a system where 2 accelerometers are connected to a microcontroller using I2C however I am unsure as to how this would actually work. In particular would I need a microcontroller with 2 I2C interfaces or would it be possible to connect them both via the one interface?


texts: Bidirectional FPGA implementations (parallel ADC)

texts:
New FPGA convert here. I am trying to interface with a parallel ADC as part of a data acquisition project. The pins on the ADC are used for both input and output (not simultaneously). Therefore, I need to drive the pins when I want to write control data to the ADC and read data values from the ADC when it is done with conversion. What are the different ways to do that? (I have an FSM driving the write and read signals so I know they are not simultaneous.)

I am currently going with the first approach (from comments) of splitting the signals into input and output versions at the top level, but I am having no joy with it. Here is an excerpt of my code and the picture of the FPGA family's IO pin in bidirectional mode:

inout [11:0] adc_data_pin_top

assign adc_data_pin_top = ~write_adc_data_n ? written_data_temp : 12'bz;
assign data_from_adc = converted_datas;

always @ (posedge adc_clock) begin
  converted_datas <= adc_data_pin_top;
  written_data_temp <= written_data_adc;
end

My problem is that I cant read the data from the ADC. My adc_data_pin_top lines 'hold' values from the previous write cycle and spit it right back to me during my read cycle. I tried to use two tri-state buffers as shown below to make sure the write values are not 'leaking' to the input ports during a read cycle but that didnt help much. I am not sure if the tri-state buffer has to be clocked or not(i.e. if I need to use a register or just wires). Also, what exact value is a tristate signal(High Z) synthesized as in hardware? 0V? 1.4V? 2V? 3.3V? In other words, what should I expect to read when I am neither in read nor write cycle? You can see a diagram of altera's IO diagram of the pin on Page 2 of the document listed below the code:

assign adc_data_pin_top = (write_adc_data_n) ? 12'bZ : written_data_temp;
assign  converted_datas = (read_adc_data_n) ? 12'bZ : adc_data_pin_top;

http://www.ee.ic.ac.uk/pcheung/teaching/ee2_digital/cyc3_ciii51007_io.pdf

Newbie alert! Sorry for all the triple-posting.

Edit: Chris, thanks for your help! The page won't let me comment on your comment, lol. So, I'm just going to comment here. The read and write signals are low enable and should be named that way-I'll fix that right now. Adding that inverter to the condition is probably redundant as well-read somewhere that old altera tools had a preference. I see what you are saying about the second statement--any high Z assignment infers a tristate buffer and I would have to pass that tri-state buffer(converted_datas) to my inner module which defeats the purpose of a split.

Further edits: Actually, on second thought, that is a GREAT idea! I do have push-button switches on the dev-kit that I can use to model an external switch. That way I can verify my HDL structure at least. But I cant read out my output signals unless I finally breakout that HSMC connector

Edit3: Hey Chris, finally got around to running that experiment today. I am able to drive the LED when the bidirectional bus is not in tristate. But because I cannot drive an input into the FPGA(and bidirectional pin) to simulate a one-bit ADC input, I cant verify that the bidirectional port is in tristate/read mode. Any ideas on how to get an input into an FPGA board with no GPIOs(except an HSMC connector)? Thanks!

Update: Yhello! Finally figured out a way to drive a signal into the FPGA via HSMC connector and was able to run a modified version of Chris' experiment--that was awesome! Now that I know my HDL bidirectional construct works, its one less variable to worry about. I figure the data being "spat" back to me is just the bus-hold feature of the FPGA board doing it work at high frequency to prevent metastability. That narrowed the possible issue down to control signal timing as I was not seeing data. Slackening the deadlines for the controls solved the problem. I am ecstatic to report my ADC is up and running! Thanks, Chris!


texts: Permanently dimming an incandescent light bulb

texts:
I have purchased a nice light bulb with long visible wires/resistors and plugged it in, on the ceiling. It burns too bright without a dimmer and does not look as intended (also the lifespan decreases).

I would like to permanently dim it. However the light switch does not have enough space inside it for a full dimmer, though I can fit something smaller. I was thinking of connecting a big resistor serially to the bulb.

Is that a good idea? I was thinking around 2 KOhm, as I figured that is the typical lightbulb resistance and therefore it would halve current. What is the difference with the 0.1W and the 50W ones? Can either take the 220V we have over here? Would it overheat closed inside the switch hole? Am I talking nonsense and should I go back to reading my uni books again?


texts: How to produce clock signals with data on serial port

texts: I am designing a Serial to Parallel converter with PIC16f84A micro-controller. Where I am going to use pin RA0 for data input, RA1 for clock input and RB0 to RB7 for parallel data output from MCU. Now I cant figure out that how to produce clock signals with data signals, since the serial port RS232 have only one pin for data transmission, and also Hyper Terminal program only use pin no. 3 for data transmission only.


texts: DSLR Hotshoe wiring to Arduino revisited one more time - When powering off the circuit, the flash always fires!

texts:
After correcting the false triggering I was getting in my last question:
DSLR Hotshoe revisited
It was related to debouncing the pulse sent from the camera to the flash, I noticed one more problem.
I built this circuit below to detect my Canon flash firing. Everytime I power the circuit off, the flash always fires.

The circuit is powered by a battery that supplies both the camera flash (with a DC/DC buck converter inside the flash) and the Arduino.
How can I adapt it in order to, if the supply is cut, the flash wouldn't fire?
I was thinking of using a P Channel Mosfet on the Arduino side, but I'm not sure on how to implement it safely, to not do something wrong with the flash or camera.
Complete schematics added for better understanding below.


texts:
I am making a SP3T switch that has PU/PD/Load.  One of these is an automotive injector that would see some intermittent current with a max of 16A @ 85V.

Is it dangerous to use solder to connect this terminals together on a pcb?
Is copper trace what I would need to opt for?
I am just worried about the current being too high and not really sure of solder's capability for this.
I am not using a PCB designer.


texts:
I am trying to understand this. When a induction motor is driven PWM Drives, the current is not chopped-up but filtered into nice sinosoidal wave because of inductive nature of motor.

I understand in a simple circuit shown below--when the voltage is first applied, the current slowly ramp up slowly.

simulate this circuit – Schematic created using CircuitLab

Now if I make voltage source to 0, the current will ramp down to 0.

Now instead of making voltage source 0, I open a switch the switch:
the current would not ramp down , but drop suddenly.

so I think in motor drives(PWM), second case is happening. So why does motor current not dropped to zero?


texts:
I am new to programming microcontroller.

what does the following like of code do:

WDT_A->CTL = WDT_A_CTL_PW | WDT_A_CTL_HOLD

i have looked at the technical reference document but i dont understand how the watchdog timer is stopped by that line of code.

can someone please explain how that code works piece by piece.


texts: How to connect PIC32MX470F512L to a micro usb connector?

texts:
I've seen some schematics and the D+ and D- of pic seem to be connected directly to the - and + of the micro usb connector.

As the micro usb has a power of +5, i'm not that confident that it would be ok, because the pic(PIC32MX470F512L) in this case is working at 3V3.

In yours opinion will it be ok to connect directly or opto couplers need to be used?

Another question i would like to ask is if - and + of USB is unidirectional or bidirectional? (I'm asking this because i plan on using opto-couplers)


texts: Simplest possible way of latching the voltage peak?

texts:
I have an input signal like this.

I wish to display the highest voltage for a period of time with LED. So I need to retain the highest voltage until the next new highest voltage comes. I tried D flip flop, but being a digital component, it makes everything 0 or 1. But in my (analog) case, say, the 1st highest voltage is 5V, the next could be 7V, and I need to preserve the values! In addition, if the next peak is 4V (<5V), I need to latch 4V.

So what is the simplest possible analog way of latching the highest voltage until a new peak (possible lower or higher) comes?


texts: What is Front Porch and Back Porch of a video signal in CRT display?

texts:
What is a Front Porch used for?

What is a Back Porch used for?

What does it mean by active video?


texts: How can I control an IR jammer or other device remotely?

texts:
I am going to buy an IR jammer kit and hide it somewhere near the tv. I need a way to remotly activate the jammer. What are my options?

I can also purchase the ninja stealth remote but I need some device that can physically push a button on the remote and I need to be able to control that device remotely.

I have a soldering iron and I"m willing to learn and spend up to $100 on new parts or things to make this work.

There is a home theater PC that I built myself connected to the TV via HDMI, I can hide an IR jammer in there or find a USB powered one possibly?

Link to IR kit http://makezine.com/projects/ir-jammer-kit/

Other option is Stealth Remote but I need something to push the button

http://www.amazon.com/Swamiware-NR42A-Ninja-Remote-Weaponized/dp/B005AZCGOI

The basic idea is I want to set up an IR device near the tv and be able to control it from another room or another level of the house. There is also a wifi router near the tv, something that connects to an open port on the router would allow the tv to be controlled from anywhere.


texts: How do I change rotation direction of single phase fan motor?

texts:
I have a single phase AC motor.  I found it from Photocopy machine.  That motor same to Fan motor.  It has a capacitor to make phase angle.  I don't know what is the correct name of my motor.

Can I change rotation direction of that motor?

edit:
This is the photo of my motor.


texts: Small-value current sense resistor value changes after assembly

texts:
I'm using a small value (~60milliohm) and small-package (0402) resistor to measure current.  When I probe the resistance with a (nice Agilent) DMM, the resistance is more like 100millohm though and it's messing up my current sensing.  I've zeroed out the probes, I've measured across five or so different samples, and the resistance ranges around 100 +/- 15mOhm.

The resistor is placed very close to a current-sense amplifier

Are these very susceptible to the reflow procedure?  If heat up the resistor too much does the resistance increase?


texts: Is Integral gain much use with a frequently changing setpoint?

texts:
I have a motor/encoder setup with a PI loop, where the motor needs to travel to a certain position following an accel/decel profile. The setpoint in this case is position at time T, which changes each time step.

Using just Proportional gain, the motor lands close enough to its target position. I investigated the effect of Integral gain, and found that even with very little kI, the motor overshot considerably.

I wonder whether there is much use in using Integral gain when the setpoint changes so frequently (500 times a second), and whether it might be better to just use it at the end of the trajectory to improve final positioning, where the setpoint remains constant.


texts: Trigger an analog SPDT switch ONLY with a long button press

texts:
I'm currently working on project where I need an analog SPDT switch to be only triggered by a long button press.

Long story short I'm trying to make a module that would fit inside a Game Boy. This module would consist of the analog switch and the long button press registration part. The switch needs to be triggered when one of the existing button on the Game Boy is pressed for a long time (let's say select held for 2-3 seconds). The switch will then trigger a different oscillator and send a higher frequency to the Game Boy, overclocking it. I've got everything figured out but the long button press thing (at least I think).

Thanks in advance for the help, and sorry for my limited knowledge in electronics


texts: Thevenin circuit, basic laws are confusing me

texts:
So the question is to find the equivalent Thevenin circuit, I did solve it using Nodal analysis, now the answer in the book is -5V while I got 5V, so it's still the correct answer, right ?

Please correct me if my understanding is wrong about +/- voltage, so we are considering V(ab), so +5V means (a) is 5V above (b) and -5V means (b) is 5V below (a) ?
And why in my solution I do get +V ? Is it because of my current direction assumptions ?


texts: Can i get away with a pcb heatsink for a triac?

texts:
so, i have a bunch of to-220 L4006L5TP triacs laying around and i have to design an AC phase control pcb, reading the datasheet i saw that the Rθ(J-A) is 50°C/W, the Rθ(J-C) is 3.3°C/W and the voltage drop is 1.6V, since the max current of the design is 1A i have to dissipate 1.6W to the pcb itself. according to this question i need a heatsink with thermal resistance less than 36.7°C/W to 16.7°C/W to keep the triac in the 80°C to 60°C range considering that the air inside the case is 45°C is it possible to achieve this with only using the pcb as heatsink with horizontal mounted triac and some CPU thermal paste? if yes, how?

tl;dr: is it possible to use the pcb as a heatsink and achieve less than 36.7°C/W using some thermal paste?if yes, how?

datasheet: https://www.littelfuse.com/~/media/electronics/datasheets/switching_thyristors/littelfuse_thyristor_lxx06xx_qxx06xx_qxx06xhx_datasheet.pdf.pdf


texts: How do I make multiple connections to a microcontroller's GND/VCC etc?

texts:
If I'm hanging a number of switches and potentiometers and other sensors off a single microcontroller, I need to connect multiple wires to the µc's ground and VCC pins.

What's the best way to do that, physically? I can think of a couple of ideas (twist the wires together and hope they fit through the hole, crimp the wires together and hope they fit in the pin, make a little daughterboard out of vero) but none of them feel neat or satisfying.

How do you pros do it?


texts:
FOLKS, am a learner. This is the problem am trying to get around.

what would happen if I use a 200amp 12V battery to run a dc standing fan of say 2amp power draw or a piano of same rating or any other dc load?  Will the circuitry of the dc load have problem since the amperage from the battery is not regulated or will the load circuitry control the amp draw hence everything will be fine.  Remember the dc load used to be operated via mains power pack but in situation where there is no power supply this comes handy.


texts: Missing steps while rotating stepper motor with gear 20:1 and driver tmc5160

texts:
as per the title I'm using Nema23 stepper motor and 20:1 gear and tmc5126 stepper driver. 1) I'm providing 3amp of current to motor and 4096 of microstepping. 2) Motor was working on same configuration with RHINO 1101 external driver but not working with tmc5160.
Am I missing something.
Tried:- Without gear Motor working fine. No issue with motor.
Datasheet can be found here


texts: What material is used in the common 5mm LED?

texts: I am not talking about the diode part of the LED, which is different depending on the color, what I am asking, is what is the material used in the conducting pins and the insulating cover? I am assuming the cover is some sort of plastic, and the pins are some sort of metal, but does anyone know the specific material these are made from? I have searched data sheets, but can only find the elements that make up the diode inside.


texts: Is higher or lower resistance wire able to heat up more? Are there other factors?

texts:
Why is it that low resistance wire in vaporizers are considered to product more heat, yet for my engineering project thin high resistance chromium wire seems to heat up most?

According to P = IV and V = IR it does seem that lower resistance wire should create a higher wattage and therefore a higher heat output, yet in the process of designing a road heating system it seems that the thinnest high resistance wire creates the most heat. Am I missing some major key of thermodynamics? Or am I pulling some kind of black magic?


texts: Is it possible to create a double layer PCB by gluing together two single layer PCBs?

texts:
I'm really in a hurry with a university project. I need to finish the first prototype of an electronics board by the end of the week. It's a through hole board, no SMD.

Having just single sided copper boards and press-n-peel paper, I first tried to go by the single layer way. I can't get to the point of a decent routing. Even using jumper wires seems unpractical. I ended having more than 20 jumper wires connecting different parts of the board.

Then I tried the double layer routing. Everything fell into place in a matter of minutes. Everything looks clean and manageable. No jumper wires, no hard-to-fabricate vias in the middle of connectors, etc...

Could it be possible to develop the two sides of the two layers board onto different copper boards and the align and glue everything together?

It looks promising to me. The hardest part would be the alignment, but to me it looks quite easier that aligning the press-n-peel sheets. I could make alignment holes and then do the rest of the milling.

Has any of you tried this method?

What are the pros and the cons?

Thanks and sorry for my bad English


texts:
First I want to say that my knowledge about electricity and physics is on 8th grade level maybe. During this lock down I've got an idea - add light in my backpack and in the same time charge my phone. Currently I have power bank ANKER PowerCore II 10000 with the following specifications

Input: 5V⎓2A, 9V⎓2A (Compatible with Quick Charge / AFC / PowerIQ 2.0)

Output: 5V⎓3A, 9V⎓2A, 12V⎓1.5A (PowerIQ 2.0)

I bought a usb cable, cut it  and connect it(black-black red-red, but also tried black-red) to led strip lights (cut again the strip and used 4 diods) with the following specifications:

Power - 14.4Watt/m

12 V DC

400mA

but the LED didn't light up.
I checked the V/A from the battery and found out that it works on the 5V, so maybe this was the case. From here I see two action points - add a boost converter or buy led module that works on 5V if there's such (way more simpler)
I have few questions, maybe really easy ones, but I don't know what I don't know, so it's really hard to me to find information and ideas:

Is it possible to charge a phone and power up few led lights from one battery and if yes, how can I achieve that?
Any ideas for a switch that triggers the led light when I open the bag and turn them off when I close it?
Is it possible to add a small switch to make it permanent stop?
Is it possible to make the light turn off after certain time when the bag is open, so it doesn't drain the battery or this includes something like arduino? (i prefer to keep it simple and not invest too much)


texts: semiconductor resistor vs resistor in SPICE modeling Altium

texts:
I'm doing some SPICE modeling using altium and would like to apply the temperature coefficients of the passive components for a more accurate simulation. However, as far as I know, in altium the passive components are "ideal" by default. So they don't have any temp co or tolerance built in. I looked around to see if I can add a external model and there is an option for semiconductor resistor and semiconductor capacitor where temperature parameter can be applied to. Can I use these model and still get an accurate result? When in reality I will be using some ceramic npo caps and some thin film resistors.

Thanks!


texts:
I have a fiber array package laser diode which draws 30A at 2.8V.  I would like to use it in a laser cutter project, but I don't know how to go about designing a power supply for it.

I came up with this criteria for the driver

Constant Current
Soft start
10A - 30A
1V - 3V
Digital or analog current control (no PWM)

I understand the basics of constant current linear power supplies, but I don't know how to scale up the current.  Could anyone point me in the right direction for power supply design on this scale?


texts: Two amplifiers in single speaker with different frequency power

texts: I have two amplifiers using LM386. One of them I plan to use for normal amplifier and the second one I want it to be a low pass amplifier/bass amplifier and both of them will be connected to same speaker. My question is: is it possible to run two amplifiers in the same speaker with different frequency (there is no high tone in second amp) and how should I wired them, bridge or parallel?


texts: Off-the-shelf Device for Logically Controlling 12V Loads

texts:
I built a circuit that allows me to control a load current using logic by using a P16NF06L MOSFET. Here is the circuit:

source

What I need now is something that does the same thing but has multiple channels so I can control multiple loads independently with separate logical inputs, has more safety handling built in (opto isolation? separate logic and driving grounds?), and is packaged better than my breadboard solution. My loads would be small - usually under 300mA and often under 1A.

I recently learned that this is called "gate driving". Is this something that I should design myself or is it common enough that others have already done it?


texts: How do the Ripple Limit lines get determined on antenna measurements?

texts:
I'm doing an S21 ripple measurement through a VNA and I understand how the measurement is done, but I don't understand how the limit is determined. I know you can specify the limit in dB and then you specify the Hz where that limit applies.

However, how does the VNA determine where to draw the limit lines for the ripple test?

For example, when looking at this test, it puts one limit line at -1.58 dB and another at -2.58 dB. Why does it choose to put the lines here and not at the line I drew in yellow for example?

If anyone can point out what I'm missing, it would be appreciated.


texts:
I was wondering if you can help me to know why my circuit is not working. I have tried with different pre-existing circuit values to make sure the circuit was working properly before I put my calculated values but I am not able to obtain an oscillating output...

Thanks!


texts:
I have a basic question about the simplest PLL scheme:

The purpose of this scheme is that of generating a signal which is a perfect copy of the input signal (which comes for instance from a crystal oscillator). The reference input signal and the output signal will have the same frequency and the same instant phase, at steady state condition.

But I have a question. At steady state condition Vo and Vi are synchronized (i.e. they have same instant phase): the output of the phase comparator will be therefore a constant voltage (that's corresponding to 0 phase error at its input), and so the VCO will generate a stable fixed frequency, equal to that of Vi.

Now, suppose Vi has frequency f1. Then, Vo will be at frequency f1 with 0 phase error with Vi.

Suppose now Vi has frequency f2. Vo will be at frequency f2 with 0 phase error with Vi.

But since in both cases phase error is 0, the constant voltage output of the phase comparator is the same in both cases. How can a same voltage value make the VCO oscillate a different frequencies in those two situations (f1, f2)?


texts:
What are Vcc and GND on a shift register?

I thought that I had to provide a positive voltage to the IC via the Vcc, but turns out that I can operate my shift register without powering the Vcc.

Similarly, what does GND on this IC mean?

I am talking about this one (74HC164A):

http://www.onsemi.com/pub_link/Collateral/MC74HC164A-D.PDF


texts: Capacitor discharging total charge calculation

texts:
I need to estimate the total charge that flowed from the capacitor for a short duration of 2ms. I am using an ATmega128 for this. Can someone advise me if analog sample/hold in front of an ADC is applicable for this? Or some other analog solution perhaps? I am not very familiar with this measurement procedure. Please see this picture:

sch;


texts: Find the Min Value of R in a Zener-Transistor Regulator

texts:
It's my first time here, and i'm starting asking a question, but I hope I can help some people in the future.

So, my Teacher showed this exercise to us and i'm wrapping my mind around it without sucess.

So he asked us to find the minimum acceptable value for R and the tension in the zener diode so that the Vout (Regulated) is equal to 5 V.

He said that the transistor is a basic silicon one, and the max power of the zener is 500 mW.

\$ V_{in}\$ is 12 V with a variation of +25%.

I found that the voltage of the Zener is 5.6 or 5.7 V (I'm not sure if Vbe should be 0.6 V or 0.7 V for this particular transistor) with this formula:

\$ V_Z = V_L + V_{BE} \$

Also found that the Maximum Current on the zener is 89 mA using this formula:

\$P_Z = I_{Z(max)} \cdot V_Z \$

But after this, I don't know what to do, and I don't even know if this is the right steps.

I'm having a hard time analyzing this regulator circuit in general.

If someone can spare some of their time to help me, I would be glad.

Thank you :)


texts:
Question from Microelectronic Circuits by Sedra and Smith, Section 17.2: Op Amp–RC Oscillator Circuits:

17.10 For the Wien-bridge oscillator of Fig. 17.4, let
the closed-loop amplifier (formed by the op amp and the resistors R1 and R2) exhibit a phase shift of −0.1 rad in the neighborhood of w1=1/CR. Find the frequency at which oscillations can occur in this case in terms of CR. (Hint:
Use Eq. 17.11.)

I had a doubt in this question.
I considered the phase shift to be provided only by the amplifier as the feedback loop provides zero phase shift for w1=1/CR and thus for oscillation feedback circuit should provide +0.1 rad so that A*beta =1.
For that I'm getting w(oscillation) to be less than w1,  which is wrong according to the solution.
It should be 1.15w1.
This problem is from Sedra Smith 6th edition. I don't know where I made a mistake.
Please help.


texts: A P type semiconductor has only free holes and an N type has only free electrons. So in an NMOS, from where do the electrons in a lightly dope P substrate come to the gate and form an inversion layer?! /isn't a P substrate supposed to have only holes??


texts: When an ideal diode is forward biased, it is replaced by a connecting wire .Does it mean voltage across diode is zero?If yes, then is zero voltage across diode condition for forward bias?


texts: Set the threshold voltage of CMOS inverter to VDD/2 for both rising and falling edge: possible?

texts:
Using 0.35u technology (VDD= 3.3v, Vt=0.7, Tox = 0.7 nm), I am trying to set the threshold voltage of an inverter to VDD/2.

If I set the width ratio of PMOS/NMOS to 5 (means the Width of PMOS would be 5 times larger than the NMOS) then the threshold voltage at rising edge of input shows a HI skew, but is around VDD/2 at the falling edge.

If I reduce the width ratio to 1 or 1.25 then at the rising edge of input I see a threshold voltage of around VDD/2, but at the falling edge I can see a LO skew.

I tried playing with Width Ratio to get a threshold voltage of around VDD/2 for both rising and falling input edges, but it seems it is impossible. I even looked at the specs of standard inverter cell coming from the foundry and it shows the same behavior.

It seems it is impossible to set the threshold voltage of CMOS inverter to VDD/2 for both rising and falling edge. Am I correct?


texts:
following a tutorial on the web I created in LTSpice a DC motor model, but I have a question about the results, the model is:

and this is the spice netlist:

V_MOTOR N001 0 PULSE(0 10 0.05 1u 1u 1 10 1)
R_MOTOR N001 N002 {R_M}
H_TORQUE H_TORQUE_PROBE 0 V_SENSE_1 {Kt}
R_Friction H_TORQUE_PROBE V_SEEN_BY_L_INERTIA {R_F}
V_SENSE_1 N004 N003 0
V_SENSE_2 N005 0 0
H_BE N003 0 V_SENSE_2 {K_bemf}
L_MOTOR N002 N004 {L_M}
L_INERTIA V_SEEN_BY_L_INERTIA N005 {L_I}
.tran 2
.PARAM R_M 0.5
.PARAM L_M 1.5m
.PARAM L_I 0.25m
.PARAM Kt 0.05
.PARAM R_F 0.0001
.PARAM K_bemf 0.05
.backanno
.end

The results are:

My question is: why V(V_SEEN_BY_L_INERTIA), representing inertia of the motor is not 0 at steady rate? As far as I know voltage across an inductor is given by L*d(i)/d(t) so as you can see by the green line when current is (almost) constant there should be no voltage drop across inductor!
Obviously this is a result we expect considering that at steady rate the motor has an inertia, but I cannot understand how it is possible being no current change.

Thanks,
Vincenzo


texts:
I have a board which has its microcontroller pins directly breaking out to a breakout header.
I am fairly certain the board won't be in ESD safe environment when being tested.

I decided to get fairly standard ESD diodes and placed it across all Digital pins. They have capacitance in the pF's so shouldn't cause any distortion there.

My question is if it is okay to place ESD diodes on analog inputs to the micro. Is there any way i reduce acuracy of these inputs?

I have been told in the past to avoid using ESD diodes on very high speed signals (in my case it was MIPI-DSI), as the very low capacitance can become significant. I am just wondering if there are other cases (analog inputs being one) where this concern should be taken?

Thanks!


texts: Information on IC with markings CT1668 HDB1144

texts:
The IC looks similar to this; I found it on Google when searched for CT1668 HDA1144

I don't even get the manufacturer name right; is it HEAD? Can anyone share its data sheet or at least some info on it? I couldn't find it on Google. Is HDA1144 the next version of HDA1134 shown in the image?


texts: Anti-Static Soldering Mat - Makes hair stand on end?

texts:
I bought this (supposedly) anti-static soldering mat, because I was ruining my standard ESD mat when I would go to reflow things.

https://www.amazon.com/gp/product/B06X97Y379/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1

When I received it, it made my hair stand on end as it brushed past. (static)

I like the mat, and it doesn't burn, but I need some way to keep it discharged. How would I do this?


texts: Brushless DC motor steady-state performance modeling

texts:
For a brushed DC motor, there are the well-known differential equations describing the electrical and mechanical behaviour:

\$V_a-i_aR_a-L_a\frac{d}{dt}i_a-k_e\omega_a=0\$

\$k_ti_a-J\frac{d}{dt}\omega_a-B\omega_a-T_L=0\$

For my purpose, I'm interested in steady-state performance. I can solve for \$V_a\$ and \$\omega_a\$ for a given input voltage by setting the derivative terms to zero.

Brushless motors are more complicated in that it's the frequency of the input voltages that determine the speed/current/torque. I wonder if there's an equivalent method for deriving the steady-state performance of a BLDC. Most manufacturers, including hobby motors, provide data on motor constants, no load current and internal resistance, so I figure this must be possible.


texts: Fundamentally knowing when to use capacitors / inductors

texts:
I've always stumbled when looking at even simple circuits that use capacitors or inductors and trying to work out why it is there, without using "past experience".

What I mean is, if we need to limit the current we know that we need to use a resistor and we know how to work out which we need. If we need to reduce the voltage to something we again know we can use a resistor.

If we need to stop the flow of current in a specific direction we know that we need to use a diode.

All this can be worked out mathematically and "learnt" as circuits 101.

But I can't seem to find out information how to know when to use a capacitor, for example: We have X and Y and wasn't Z... "Oh so we need a capacitor here".

All the explanations for capacitors I've seen in circuits have been from peoples practical knowledge or past experience... without that, you wouldn't have known that you would have needed a capacitor.

My brother who's doing some electronics in school brought a simple circuit diagram home that they are making and yet there's a capacitor in it.

How do you work out and know that you need a capacitor without relying on past experience "I found if I stick in a capacitor it helps..." how do you learn or know when to use a capacitor from the start / design stage?


texts:
I am currently working on a high voltage boost converter based on Dos4Evers 555 timer based one https://www.dos4ever.com/flyback/flyback.html (12v to 140-220V). I am running into an issue with the output voltage. On start up the output voltage hits ~30V and holds there for a while. After some seemingly random time it then jumps up to 110-130V, finally it will sometimes then jump again up to 280V. I am sometimes able to cause the voltage change by pressing on the components with tweezers or a screwdriver, however it doesn't seem to matter which component I press on. Here is a schematic of the circuit.

I've measured the high side output of the inductor with the scope both when it is sat at 30V and when it is sat at 120V shown below.

I also have a version of this built on a perf board and on a board I made a year ago, they both show the same result on the output (this is working properly at 146V)

I also tested out the HV side of C5 and the working version has as expected a ripple, however the non working board has no measurable ripple. My first reaction is the non-working board looks like the output of an LCR circuit but I'm not sure what would be causing this (I could also be wrong about that).
Also in case the cause is some silly mistake in my layout, here is the PCB layout.


texts:
I am trying to model an RS-485 bus in LTSpice that consists of two power conductors and two data conductors within a single cable. The power conductors are twisted together and shielded, and the data conductors are also twisted together and shielded. The shield is not connected to ground -- it is left floating in the current setup. I inherited this project so I am going with what I have.

This cable will extend for a few thousand feet and I am looking at the impact the length has on the bus voltage, and its susceptibility to supply droop when one of several circuits, placed along the cable, switches on. In order to model this in LTSpice I have been trying to determine what factors apply, such as series inductance and resistance, parallel capacitance, mutual inductance between the conductors, and so on. However, I'm not sure all of these apply.

The basic model for a differential data transmission line consists of two conductors, each with a series resistor and inductor, and a capacitance between them. Additionally there is a high value resistance between them, but I am considering that negligible in my case.

However, there are four conductors plus a shield in this cable (two power, two data, and one drain/shield) which I am assuming are located fairly symmetrically in a square within the cable around the drain conductor:

In order to get an accurate simulation I have been trying to model this complete setup by adding two more conductors with series resistance and inductance, parallel capacitance to each of the other conductors, etc. Additionally, I have been trying to calculate the coupling coefficient between the cable inductances so that I can simulate it in LTSpice. However, I am not at all confident that I am doing this correctly and how much I really need to take into account. If I extended the elements from the two cables to all four, I came up with something like this:

Ignore the Rp, I am not worried about that right now.

Am I going about this correctly? Am I leaving anything out, or including something I shouldn't? I realize there will probably be capacitance between each conductor in each pair and its shield as well, but I'm not sure whether or not to include that. Also, I am assuming the mutual inductance between each of the conductors and each of the other ones are identical (which in reality they won't be, but I'm just trying to get a basic idea). This is why I have the K1 L1 L2 L3 L4 0.48 statement. I'm not even sure about my math to get 0.48, but that's another question in itself.


texts: Will this schematic work - basic LEDs + strips

texts:
This is my first LED project for my art bike and after a good chunk of reading, I wanted to know if the circuit would run properly.

LED are green 5mm from AliExpress. Forward voltage 3V-3.2V,  20mA

There is also a green LED strip in the design from AliExpress. 2835 SMD green lrd strip - use about 15 LEDs length. I'm guessing I won't need a resistor since it's 12v.

The battery will be 8xAA batteries. If my math is somewhat accurate about 24 hours run time - 16ah / 0.62ah -i.e (2000mah x 8 AA Battery) / (20mah x 31 leds)

I'm planning on using 22AWG if that makes any difference or should be advised on another size.

^ Here is an edited version #2 with a voltage converter... and 3.6 battery


texts: Understanding CS5463's acquisition circuit

texts:
We can consider this question to be the sequence of this previous one.

Now I'm working on the current and voltage acquisition part (red marker) of the CS5463 (datasheet).

  The CS5463 is an integrated power measurement device which combines
  two analog-to-digital converters, power calculation engine,
  energy-to-frequency converter, and a serial interface on a single
  chip. It is designed to accurately measure instantaneous current and
  voltage, and calculate VRMS, IRMS, instantaneous power, apparent
  power, active power, and reactive power for single-phase, 2- or 3-wire
  power metering applications.

First of all, one question about the spec:

The datasheet page 16 contains: "the full-scale differential input voltage for the current and voltage channel is +/- 250 mV". From this, I assumed this channels can receive voltages from -250mV up to 250mV, and the reference for this values is the AGND pin. Am I right? (This information is kid of confirmed on pages 7 and 8.)

About the circuit itself, this time, I'm having more trouble to figure it out. My intuition says it's a simple voltage divider to measure the voltage and a high power resistor (shunt) to measure the current. The circuit is almost that, but I don't know the purpose of the extra components. And without knowing it, I can't define their values correctly.

First question: why all the circuit considers the "line" as the ground and not the "neutral"? This way, all the waves are inverted to the originals. What's the advantage of doing this?
What happens if I plug it inverted, in a way that the IC's "neutral" connects to the "line" of the outlet and vice versa?
The R1 and R2 is a voltage divider block. The peak voltage in my region is 311V (220V RMS). Aiming for a 250mV peak, I chose the values 10 ohms and 12.4 kohms (if this last one doesn't exist, I'll put an approximate one or some resistors in series).
The shunt resistor may be of 25 ohms. If a maximum current of 10A passes through it, it'll dissipate 2.5W and generate a 250mV voltage.
How many mV should I leave as a safe range in this case? These values can be rezised to leave a safe range of 50mV above and bellow the waveform.

The remaining components:

I can't identify their purposes. So, I can't size them correctly. The Cv+ capacitor has the grounds between its terminals, so what's it goal? This capacitor and the Rv- resistor appear to be a RC filter. But I've never seen one plugged on the ground. The Cv- and Cvdiff… I have no idea what they do. I can say the same for the equivalent components of the current sampling circuit, which also has the Ri+ resistor (without an analogue component on the voltage circuit).

The questions are scattered all over the question, but any doubts you have I try to summarize here below.


texts: How to "clean" a DC brushed motor : noise on CANbus even without moving!

texts:
We have very odd problem with a DC brushed geared motor that we are driving with a classical H-bridge chopper (20kHz PWM at the moment). The motor kinda looks like a Mabuchi from an R/C car but with an epicycloidal gearbox in front of it.
We had another motor from another manufacturer that was working perfectly but with this one the CANbus keeps dropping frames as soon as it is even connected with the speed controller. Not even moving! Just connected with no current whatsoever.
We've tried various controllers and also various motors (same model) and the problem doesn't change.
We've also recently seen some problems with low voltage signals picking up noise when it's connected.
The only fix is to use a separate CANbus AND power supply. In all other cases, problems keep on piling up.
We've put different toroidal chokes and went up to dozens of turns into big ones but while that helped, definitely not enough...
Any idea or lead that we could follow?
Thank you all by advance,


texts: What is the purpose of the Arduino Uno power pins section?

texts:
I have an Arduino Uno, and from what I understand, the digital I/O pins on the side of the uno  each have 5V and can be controlled from the Arduino software.

I am pretty sure from reading the documentation and testing it out with a 9V battery (Please correct me if I am wrong) that the VIM and ground pins on the opposite side of the uno are used for powering the uno from an external, non-USB power source.

What I find a bit hard to understand from the uno's documentation, is the purpose of the 5V and 3.3V pins. I tried hooking up a hobby motor to the 5V and ground pins, and it spun - so am I correct in deducing that the 5V and 3.3V pins are used to power external components that don't need to be controlled from the Arduino software?


texts:
Does anyone have any directions on what ICEs exist for MSP430s.

I currently use the MSP430F148. I have others in use, and plan to switch to some higher end in the future.

I would be interested in ICE or any other solutions people know of. We have some real time systems where power consumption is more important than speed(excluding the deadlines we must hit).

If anyone needs clarity on the question, just pop it in the note and I will try to revise this.


texts:
What do you do when you want to simulate a signal (i.e with Hyperlynx) but you can't find the IBIS model of the receiver chip?

What parameters do you need? Where can you find them?