texts:
I am having a hard time to calculate the baud rate for the following:

Needed baud rate for 2 bytes data at 1KHz over an UART port with a 8N1 protocol

Thanks


texts: Duplicate designators in a panelized design in Altium

texts: I am using Altium 21. I am panelizing the design using Place -> Embedded Board Array/Panelize menu in a PCB editor and later output the Pick and Place centroid file from the resulting panelized .PcbDoc. When I do that I get duplicated reference designators in the output centroid file, which the PnP machine can't use. Is there a simple way to make Altium increment the reference designators from one board to another on a panel so that they are unique? I was searching through the documentation and couldn't find anything like this even though it seems like simple feature.


texts: Why a hole is not formed when 5th electron of pentavalent impurity moves to conduction band in n type semiconductor?

texts: In intrinsic semiconductor, when an electron moves from valence band to conduction band, hole is formed in place of that electron. Why does that not happen in case of n type semiconductor when 5th electron of pentavalent impurity moves to conduction band?


texts: PLL integrated CCC, Microsemi/Actel ProASIC3 nano Flash Family FPGA, A3P125

texts:
I have Micosemi/Actel ProASIC3 Nano A3P125,VQ100 Chip. I was looking for the PLL integrated CCC to connect 100MHz Clock and I have been through the manual ProASIC3 FPGA Fabric User’s Guide. where i have found, i have three options(3pins) like "GFA0, GFA1 or GFA2". It's clear from manual that 'Only one of the I/Os can be directly connected to a chip global at a time'.

what about the rest of two pins? Can I use them as output?


texts:
I have a small board that I designed myself containing a XC2C64A cpld that has 8 LEDS connected to output, and 2 input. It's not what I would have designed for this project but it's what I already have as I made it for another learning project to learn how to design and get pcb's manufactured.

I've connected the inputs to my Raspberry PI's GPIO ports and using one the pins as a clock (as there is no clock available on my board) and another for data and I can make it do things, so I know that everything is working electrically and it can read and write data between the two devices.

However I want to be able to send it a few commands over the single pin I have available. For example setting an LED on, setting an LED off, shifting them left, shifting the right, setting an auto-left rotate etc.

My question is what is the best way to do this? My first attempt was to write some verilog which expected 3 bits for a pin number followed bit on or off to handle the simple case of setting an LED. Now that works, sort of, but there is no way to synchronise it, I can't tell the difference between 000 - 0 to turn off LED0 and just being idle!

Has anyone got any suggestions how best to send my data over this single pin? It needs to be very simple as there isn't much space for logic on the CPLD once I've added in logic for the LED control.

Thanks for any suggestions :)


texts: What do the terms "cuts" and "jumpers" mean?

texts:
specifically, with respect to the electrical grid.

Here's an excerpt from something that I'm reading that I don't understand:

  Switching operations, including applying cuts and jumpers, can be operated in ganged (all phases in one operation) or un-ganged (one or more selected phases) mode.


texts: I can't understand why GPS reciever clock is very good (stratum 0). I know it's very accurate and pure within itself; but when it passes through a long distance wireless channel, then it has low power and much noise and jitter, so how it can be better than other clocks?


texts: How to scale output of butterfly unit radix 2 for further stages?

texts:
I am designing 8 point FFT by radix 2 using verilog. I am using radix 2 butterfly unit with 8 bits input and so output. I expect to be 8 bit so that I can use this structure again and again for further sta. I am applying DIT. If I consider my twiddle factors are of 8 bits stored somewhere then I multiply to one of butterfly inputs result is 16 bits, and when added/subtracted to other input output is for sure going to be min 16 bit/ 17 bit. But I expect my output to be of 8 bit so that same butterfly with 8 bit input can be used. How do I scale this without loss of accuracy

      module butter_fly(xr,xi,yr,yi,wr,wi,xxr,xxi,yyr,yyi);

     input[7:0] xr,xi,yr,yi,wr,wi;
    output[7:0] xxr,xxi,yyr,yyi;

    wire[7:0] xxr,xxi,yyr,yyi;
    wire [7:0] xr,xi,yr,yi,wr,wi;   // wr and wi represents twiddle factor
    wire[15:0] w1,w2,w3,w4;

          assign    w2 = yi*wi;
          assign    w3 = yr*wi;
          assign    w4 = wr*yi;
          assign    w1 = yr*wr;

            assign  xxr = xr + w1 - w2 ;
            assign  xxi = xi + w3 + w4;
            assign  yyr = xr - w1 + w2;
            assign  yyi = xi - w3 - w4;
endmodule

I am exceeding these 8 bits in my ouput. since these output will become input to my next stage. the next stage also consists of radix 2. This obtained output I can not feed into it. It has to be 8 bits. So how do i scale this output of butterfly so that it can become 8 bit type input to next stage butterfly unit. I expect my final output to be correct at last.

let me know if you do not understand


texts: Why is Inrush current important to me when buying a power supply?

texts:
I am in the process of buying some power supplies and was looking over the datasheet at saw the inrush current is stated as "Coldstart 80A/230VAC"

I can also see that the AC Input is rated 1.1A/230VAC.

Now I know that the rated 1.1A determines how much the power supply could potentially draw during operation. But I do not understand the inrush rating. I know that inrush current happens at startup very very briefly. But I a bit terrified by the 80Amp rating.

How should I understand this rating if I what to plug it is not a normal wall socket at home?

And does it have even more serious meaning if I plugged 5 of the same one into the same wall socket?

For reference here is the  complete datasheet for the power supply:
http://www.meanwell.com/webapp/product/search.aspx?prod=UHP-200(R)#1


texts: Can Nios II custom instruction feature be used to create SIMD type instructions?

texts:
Nios II is all about customizing, the essence of a softcore. Custom instruction is an interesting feature of the Nios II.

Custom instruction involves 2 inputs dataa and datab. Does this mean that it is not possible to create SIMD type custom instruction? Can the register file of a Nios II processor be extended so it can be shared with an SIMD type instruction?

Note: Purpose is to hardware accelerate image processing algorithms with a Nios II.


texts:
I probably need help more with terminology (and thus, how to find the answer that already exists) than with technology.

My current hobby project is a low-power device — max current is 100mA at 5V* — which is intended to be a pneumatic water level sensor. The basic operation is to drive a small air pump for a very brief period (about 200ms), wait a moment, then read the pressure, repeating these steps until subsequent pressure readings differ by less than the error margin of the pressure sensor.

The catch is that there is so little current available that the pump sometimes stalls at that tipping point between poles. It's a 6V rated motor which I've successfully driven at voltages as low as 3V. At 5V it draws about 150mA when running (measured on a slow-sampling multimeter).

Being naive and still young enough to know everything, I'm thinking of adding a largish capacitor between the power rails, with a resistor in series to charge it up. For example I might use 100µF with 1kΩ, which at 5V should keep the charging current below 50mA, more than enough to keep the power supply happy. Then "crowbar" the resistor out with a FET that is turned on when the pump needs to be driven (not that "crowbar" is a term that really applies to currents in the order of 100mA).

I probably need some other kind of device (maybe a P-channel FET?) for the crowbar, since it's going to be turned "on" by bringing the gate voltage from below the source up to the same as the drain (Vgs will either be negative or zero):

simulate this circuit – Schematic created using CircuitLab

My main question is: what is the terminology for this kind of setup where I'm intentionally catering to the high current inrush of the pump motor with a power supply that can't deliver that current?

Secondary questions: is what I'm doing in any way "normal" or sensible? Are there some references I should read up on before proceeding further with this project?

the power supply is a solar LiPo charger with a USB 1.0 output, so 5V at a maximum of 100mA.


texts: How can I interpret the readings of a USB voltage tester considering the input voltage is 5V and I am charging a 3.7V battery?

texts:
I have this USB voltage tester that I place between my usb wall charger and a USB charging cable. This device gives me the total current that went through over a period of time. Let's say after 2.5h of charging I get this:

IN: 5.22V
TIME: 150min
0.835A

And that means over the duration of two hours and a half 835mA passed through at roughly 5V (that somewhat varies a bit)

The thing is, the device I am charging has a 3.7V battery with a total capacity of 800 mA. And this is where it all gets confusing to me:

The total power that went through should be ~5 x 0.835 = 4.174W

However, the 3.7V battery can take 3.7 x 0.8 = 2.96W = ~3W

That's over 1 Watt difference that I don't know where it went. The charging takes place by plugging a miniUSB cable directly in the device that holds the battery.
The device has a display that briefly gets lit the first 15 minutes but then I managed to shut it down and remains black throughout the charging.
There is also one red LED that stays on throughout the charging duration and then turns off.

Should I believe over a quarter (over 1W) of the power passed through is waste? Or is my math wrong?

Edit: full charging video available here
https://www.youtube.com/watch?v=5kYaG2KwxDw


texts:
I want to charge a battery my power supply is 6V ,
I Need to add a battery to my circuit and need to charge it for a long time.
should i add a switch in series or in parallel to the diode?
this is my schematic :


texts: What is the recommended way to protect a circuit from non-transient overvoltage?

texts:
I'm designing a 12V battery-operated portable lighting controller, and frequently am asked about improving the run time. The simplest way is to add a second battery in parallel, but I often worry that users will get it wrong, hook up the batteries in series, and provide 24V instead.

What's the best/recommended way to protect a device from an overvoltage situation like this, (where double the voltage is applied for a length of time that I would not consider to be transient)?

In this case, the controller uses no more than 100mA as this particular one simply flashes LED's rather than sourcing a lot of current. It has a couple of voltage regulators that are only capable of handling up to 15V input.

I've been experimenting with Zener diodes and transient voltage suppressors (TVS) but with mixed results. I'd prefer that an overvoltage situation (such as 24V applied) to trip a circuit breaker (PTC fuse) and protect the voltage regulators and microcontrollers. If someone connects the device to mains (120V), they're on their own!


texts: Open collector and open drain logical gates

texts:
Can somebody explain what  open collector and open drain mean?

I'm a CS student, and I'm really a newbie in terms of electronics and I only managed to find some "expert level" explanations, which I can't really understand.

I need an explanation mostly in terms of logical gates that uses them (their speed, power usage, price(?) and other features etc.). My professor only gave me these pictures, without any explanation.

I don't even know which ones are open drain and which are open collector.


texts: To generate FULL/EMPTY for FIFO control, the reading address/writing address needs to be transferred to the writing/reading side for comparison. A solution is to use gray code for the address to be safely delivered to the different clock domain because of only one bit will be flipped at a time. This is good if the depth of the FIFO D=2^K because only one bit changes for the transition from D-1 to 0. But what if D!=2^K, e.g., 13? The gray code is 1010 whereas the next address is 0000, for which 2 bits will be changed, and the 2-stage synchronizer is unsafe for such change. How is this problem solved for FIFOs with arbitrary depth? Will more complicated synchronization schemes be used? If yes, it seems converting from/to gray code is no longer necessary.


texts: How step-down voltage regulators behave when their input drops below their output voltage?

texts:
How do the common low-dropout LP2950 and buck LM2596 regulators behave when their input voltage drops below their output voltage?

I'm driving a micro-controller board rated for 3.7-5.5 V with a 4.8V battery pack built from four 1.2V NiMH cells.  1.2V NiMH cells range from 1.45V freshly charged to slightly below 1V, or whenever you wish to start worrying about polarity reversal.

As I understand it, one should usually use a buck like the LM2596 for efficiency reasons.  LM2596 boards all claim the input voltage must exceed the output voltage by at least 1.5V or even specify a minimum input voltage of 4V.  I'll want the device running while the pack still exceeds 4V though, but 2.5V = 4V - 1.5V sounds too low, although not necessarily.

What actually happens when an LM2596's input voltage drops below output plus 1.5V?  Does it stop working or become unpredictable?  Or does it supply the input voltage minus 1.5V?

Are there LM2596 that bypass themselves or switch to an internal LDO when the voltage drop gets too low?

Also, I imagine an LDO like the LP2950 would continue dropping the voltage by it's minimum drop.  Is that correct?


texts:
So this may be a terribly stupid question but since my RF knowledge is fairly limited I'm asking it anyway. Let's say you have an AM signal that's 5Vp-p at some frequency. To amplify this can you simply scale up the voltage and send it to the same antenna? Also, are antenna's rated for a certain power input/output?

I'll try to clear up my question somewhat. I am only asking in regard to transmission, assuming the system works at low power levels and all matching is at acceptable limits.


texts: Detect if 3-phase 110VAC motor is running via 24VDC PLC input

texts:
We have an industrial machine with 3-phase ~250W AC (~2.5A @ 110V) motors on it.  I want to non-invasively detect if the motors are running.  That detection signal needs to feed into the 24V input of a Koyo Click PLC.

After some Googling and part-searching, it seems like I could use a non-invasive current-sense transformer, but the output looks like it's AC with a scaled current.  I still have to convert an AC -> DC signal.

I've also looked at various relays, but their input current requirements are generally very low (< 50mA).

Am I on the right track here by using a current-sense transformer that drives a solid state relay with AC-driven coils?  Or is there some easy-to-grab part that I'm missing?  I'm looking for something that is in-line, chassis mount, or DIN rail basically (no custom soldered circuit please).  My background is in PC software development, so this mini-project has been giving me fits.


texts: Is a relay with a 20 amp rating enough to handle the current from a residential hot water heater?

texts:
In Israel the houses usually have a hot water cylinder on the roof of the building which is attached to a solar water heating unit, but which also is connected to an electric heating element which is switched on from the inside of the house if there is no sunshine.

My goal is to rewire the indoor switch to be connected to a relay and then control the heater from remote. I plan to do this using either Arduino or Rasperry Pi connected to the internet.

My question is, assuming (I will double check this) that the heater uses a maximum power of 4000 Watts (4 kW), which divided by 220 volts is around 18.2 Amps, will a relay that is capable of handling 20 amps be able to handle such a load? I'm thinking of using the SparkFun Beefcake Relay Control Kit

I'm under the impression that with heating elements there is generally no surge in electricity and that I don't have to worry about it spiking, unless something goes horribly wrong, G-d forbid.

Also, SparkFun writes that, "There are some pretty beefy traces connecting the relay to the load pins, but the 2-pin terminals are only rated for 8A max! If you plan on connecting a larger load you’ll need to solder directly to the board." Will soldering directly to the board allow me to pass such a high current?

Thank you.


texts: What causes the common mode gain in MOS differential amplifier

texts:
I went through many of the past questions in this forum and also a lot of other sites but none answered my question, so I made up my mind to post it here.

What exactly causes the common mode signal to appear at the output side ? I know that the transistors are not symmetric and this causes an offset but assuming the transistors are all symmetric, what causes the common mode signals not to be rejected completely ?? I think this has to do with the tail current source not being ideal but how does this exactly affect ??


texts: Does the use of power surge protector makes up for the lack of the ground pin?

texts:
My office room in my apartment has only sockets with 2 pin (USA).

However, my Macbook requires a 3 pin socket so does the external monitor and other electrical equipments.

Will the use of power surge protector (using 3pin to 2pin socket converter) help make for the lack of safety due to missing ground pin in the wall socket?

Power surge protector that I have is from Belkin.

3pin to 2pin converter is an international adapter.


texts: Matching radio tubes - what is widelly accepted tolerance in parameters?

texts: When matching radio tubes, most important parameters are anode current and transconductance. Is there widely accepted tolerance in parameter variation? I have read an article where tubes are considered as matched if anode current is within 5% static Ip and transconductance S variation is 10%.


texts: Meaning of "grounded" in a uniform field

texts:
I am reading an example in a book which considers a grounded conductor inside a uniform electric field. The author stated that "grounded" means, as usual, \$V=0\$. But I am confused.
In my opinion, "grounded" means having the same potential as the potential at infinity, which is usually set to zero. Now there is a uniform E field, and I don't think "grounded" still mean "same potential as at infinity. So what does it mean by a "grounded" conductor in this case?


texts: Replacing the selenium rectifier in a vintage car battery charger

texts:
My battery just died yesterday (actually left the lights on). Took it out for charging today but my new automatic charger for detect such low voltage to begin the charging process. So, I had to hook it up to my great old Lucas charger (attached pic below) but only to notice there was no defection in the ammeter. I checked with my multi-meter and found the output was like just 0.24V, opened the case and checked the transformer an it was fine. Looks like a blown rectifier-selenium rectifier I guess (pic below). After a futile search found these rectifiers are no longer available, so finally got a KBPC2510 metal bridge rectifier. I've installed it on the battery charger and measured the out put at 6V and 12V setting gave me 6.9V/11.9V open circuited and when connected to the battery the outputs rose from 6.8- 8V for 6V battery and 14-15.8V for the car battery as it got charged .

Is this because of the metal bridge rectifier? I haven't had the chance to measure the volts with the old rectifier before. Are these voltages bad for these battery? ]2]3]4


texts: Can I use the same power supply to double the voltage?

texts:
I want to do a corded conversion as seen in this link
.  However, some Makita tools use dual batteries to have a 36V source.  That means the voltage from the 18V power supply will be combined to create a 36V source.  Will this present any problem


texts:
First at all, thank you so much for all the answers I have received on all the threads. Well, I'm working on PCB Raspberry Compute Module 4 Carrier including USB 3.0 Controller (TUSB7320) using PCIE lines. I have inspected this layout guide:
https://www.ti.com/lit/ug/sllu149e/sllu149e.pdf?ts=1619089469669&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FTUSB7320
But It create some doubts about priorities of rules. TI recommends reduce the number of vias and reduce the length of the traces. What is the stronger rule? In the first picture I avoid using more vias incrementing the length (much less than the maximum length that TI recommends). What is better?

On this picture I can't use narrower traces (I would need 0.10 mm width trace to put the trace between pads) so the number of vias is not equal for these two lines. Should I to create 2 vias to change the layer and matching the length for the two layers?


texts: Flat profile IDC type connectors and cable replacement

texts:
Hello guys I am looking to replace IDC connector on my project board with something flatter like the ones found in laptop. The problem as I do not have any guide to go around to look for the right connector. I have tried using right angled IDC as a compromise but I am looking for sth similar so that the cable housing and the IDC connector do not stick out more than 5 mm in height on either side of the pc. Any ideas on replacement will be appreciate. My current connector is 20 line DIP.

Note: The problem with right angled IDC is that it makes disconnecting the cable a perilous endeavour. I have lost two boards because of this :(

I want to use a cable like this enter link description here But cannot find its housing and latch.


texts: Get multiple individual DC voltage sources from a single line

texts:
If I connect 2 6V batteries or two individual sources serially the combined voltage should be the sum of the voltage of each battery (i.e. 12V). Is it possible to get 12 volts from a single source or battery of 6 volts? Actually I have to power my DSL router of (12v-700mA) from my laptop's USB port (5volts).

Schematic diagram will be highly appreciated.


texts: The instability of Collector current(Ic) of a transistor depends on three factors viz. Icbo, Vbe & Beta. Can you explain why Vbe decreases(by 2.5 mV/°C) with increase in temperature?


texts:
I'm working on a project that uses a GPIO port extender, but I need the ability to sink more current on the GPIO pins.

There are 24 GPIO pins.  Each pin can either be input or output.  The pins need to sink 50mA individually and up to 200mA over all.

Is there a small package that can help with this?  Or maybe there's a port extender that already does this that I don't know about?


texts:
I'm making a PCB for an audio amplifier + power supply (circuit here).

The power supply voltage rails with my transformer end up being about +/- 37V, and I want to generate a 5V rail from this for powering some cooling fans on the same PCB. This is pushing the limits of a typical voltage regulator (e.g. the max. input of a L7805 is 35V).

I tried a DC/DC converter (a R-78C5.0-1.0) but this produces audible noise on a speaker at the amplifier output (I put 10 uF decoupling caps at the input and output). One thing I didn't try yet is the EMC filter suggested in the datasheet here.

I found "high-voltage regulators" (e.g. an LR8), but the max. output current is 30 mA, and my fans need about 100 mA.

Is there a better way for generating 5V from 37V without producing EMC that I can hear as noise on the amplifier?

UPDATE: I'm an idiot. It turns out the noise was coming from having some signal wires too close to the transformer. I rearranged everything and now I can use the DC/DC converter without producing any audible noise at the speakers.


texts: STM8 ST-Link high power consuption & unable to connect

texts:
I have a ST-Link V2 and I am trying to connect with SWIM. So, i simply connect the pins, but the power consuption is very high (80 mA!), so high that che voltage regulator gets warn. In STM32CubeProgrammer, it shows 1.85 V voltage detected, while the real voltage is 5 V.
The ST-Link is dectected but unable to connect to the target, as nothing is connected to SWIM pin.
What is it happening?
In the schematic below I am showing the ONLY devices I've mounted and I use in the board, obvioulsy beyond +5 V and GND. As you can see, its a extremelly basic configuration.
Thanks,


texts: Need assistance in rare battery identification

texts:
Whilst looking for a battery for one of my many projects, I found this small battery in a box of parts I had - I have looked everywhere I know online so far and have not found anything close, apart from a 12v 23A rf remote battery.
These batteries are 1.2v and 28mm long and 10mm across. Very similar to a AAA but half the height. No identification apart from a chinese battery manufacturer that no longer exists.
Would anyone be able to identify this cell?


texts:
Some time ago, I received a care package from the US, which included a glue gun (specifically, this one: https://surebonder.com/collections/plus-series/products/dt-270f-plus-series-40-watt-full-size-dual-temperature-hot-glue-gun) which is rated to use US mains power. Living, as I do, in Norway, 115 VAC is not readily available as the default in these parts is 230 VAC.

What I am wondering is, if I replace the plug with a Norwegian one, would it be safe to use on a Norwegian outlet?


texts: Simple 24V to 5V converter circuit (Almost complete)

texts:
A couple of years ago I made a 24v to 5v circuit and it worked well. So I followed the same schematic.

My question is that I have no idea why I used those capacitors. Does it really matter what capacitors I use?

My circuit will only use like 50mA.


texts:
I'm designing a compact PCB.
It consists of non-addressable 5050 RGB LEDs.
I'm concerned about how close they are. I'm going to use the SMD assembly service provided by JLCPLB.
Should I change the design?
Please feel free to recommend any other solutions, I'm all ears.


texts: How do I calculate the average voltage of this wave?

texts: I need to calculate the average voltage of the wave below, the DC voltage is 120 V , the curve starts at 21.65 degrees and the peak voltage is 325.269 V. The solution is 221.3 V. This is from a uncontrolled full-wave bridge rectifier with RE load, the source is 230V rms at 50Hz, R=2 ohm and E=120V. I tried calculating the average voltage of the rectified sine wave and subtracting the average voltage of the portions before the curve starts.


texts: Multisim Mathematical Equation for AC Sweep Analysis

texts:
I am trying to create a simple bode plot from an AC analysis sweep in Multisim. As shown in the picture, I have my voltage V(PR2), and I have created an expression for 20*log(V(PR2)).
However, this expression is not outputting what I am expecting. For instance, at the cursor, the voltage for V(PR2) is at 0.705 V. For the mathematical expression, I would expect 20*log(0.705) to be around -3. However, I am getting a value of 16. What is causing this?


texts: Messages sent when keyboard key is pressed

texts:
When pressing keys on a keyboard what messages are sent to a PC?

Is it OK to send this message using a micro controller (through USB cable)?

This is the protocol format i got from website.

how to send these packet?

for example,

when pressing key 'A' ,
what commend to send pc for displaying 'A'.

if i am sending this commend using a micro controller (through USB),
is it display character 'A'?

This is the document i am refer


texts: How to calculate the earth fault current in a transmission system with no ground wire?

texts:
Background information, and my thought on the matter are provided in the end of the question.

I need to calculate the fault current in case a fault occur for instance 10 km away from a transformer station, for different types of soil when the transmission lines are lacking an overhead ground wire (used for lightning protection and for carrying fault currents).

In order to calculate the fault current I need to know the equivalent resistance between the fault location and the transformer. How can I use information about soil resistivity to calculate this?

Will the soil type between the fault location and transformer station influence the fault current?

I haven't been able to find any sources for this. Any help is appreciated.

My thoughts:

The soil resistivity between the fault location and the transformer station is irrelevant. The fault current is driven by the earth potential difference, and this can be different even if there is no/bad electrical connection between the two locations, because the earth is so big. After all, it isn't the same electrons that make up the fault current in the fault location and in the transformer station.

I only need the earth resistance out to a certain radius out from the fault location, and the earth resistance in the transformation station and I'll have enough information. Unfortunately I don't know how to calculate the equivalent resistance in the fault location.

Background information:

High / medium voltage transmission grids / distribution grids are usually equipped with a ground wire that will carry the fault current back to a grounded transformer in case of a line-ground fault. When calculating the fault current you need information about the zero sequence impedance of the wire and transformer, and you're good.

However, if no such ground wire exist the current will have to return through the ground.

It's possible to measure the resistivity towards ground in the transformer station using for instance earth ground tester (this is normally used in order to calculate step voltage etc).

There are many tables online that list the Soil resitivity of different soil types. For simplicity I'll refer to the table provided by Fluke (see table below).


texts: LED hard-connected to battery - what is the purpose of this device?

texts:
Recently, while crossing a parking lot at night, I noticed a faint light on the ground. Approaching it, I realized it's a small device loosely lying in the dirt, obviously lost by someone. There was no car or person immediately nearby, so I took it home to investigate.
The device is about 2 cm long and 1 cm in diameter. Its housing appears to be a piece of plastic that can be click-closed, but was additionally sealed, perhaps by heating and melding parts of the plastic.
On the inside, there's nothing else than a simple green LED whose electrodes are directly connected to either sides of two button batteries - unless I'm missing something there is no switch or other mechanism to turn the light on or off.

What kind of device is this, and what is it used for? Also, are my observations correct?


texts: Can the MINI Wemos D1 ESP32 handle 5v on its GPIO pins?

texts:
I need to connect multiple data and address pins of a Z80 processor, which runs like the rest of my circuit on 5V, to the gpio pins of a mini wemos D1 Esp32. But I am not sure if the wemos can handle 5V input. I have tried to search for an answer but most of the answers I find are oppositions from each other. Some say it is ok to put 5V on the GPIO pins some say it will kill the chip.

So do I need to regulate the voltage or not?

Thanks.


texts: LilyGo Sim800C vs Tiny Sim800C Module, Why so many components on LilyGo?

texts:
I have been trying for some time to create a custom board based on LilyGo ESP32.
I found the schematic too complicated for me and that is why it took so long.
Now I came through a "tiny" SIM800C board Board was found here
Why in LilyGo board they use a so complicated, expensive way with so many extra components to do the "same" thing? Schematic is here on page 3.
I am not talking about Power which obviously is not included on the power board, neither speaker and mic.
But look at the Sim card, PWERKEY, GSM_RXD, GSM_TXD, S_DTR, S_RI
The tiny board can be perfectly connected to the ESP32 using the TXD, RXD pins and work like a charm. Example is here
without all those extra components.
What is the point? What am I missing?
Simcard is so complicated on the LilyGo while on the tiny board it looks so simply connected.
EDIT:
I do understand that the small board cannot work alone and it needs the ESP32.. I am only wondering why it has so complicated schematic the sim800 part of the lilygo


texts: Address decoding different bank sizes in 64K memory

texts:
I'm doing a small Motorola 6809-based computer project, and since I'm a bit rusty when it comes to boolean algebra I'm wondering if I'm doing my address decoding a bit too complicated for my simple use case.

What I want to achieve is the memory mapping show below. I've divided it in this way since I have four ICs (2 x 62256 32K RAM, MC68B50 UART, 8K 28C64 ROM) mapped into memory.

0000-7FFF : 32K RAM (LO-RAM)
8000-BFFF : 16K RAM (HI-RAM)
C000-DFFF : UART (minimally decoded)
E000-FFFF : 8K ROM (monitor)

I'm thinking of using a 2-4 decoder to divide the upper 32K of memory where the first 16K reserved for the HI-RAM. For simplicity's sake I'm lazily mapping the UART into an entire 8K block, and using the last 8K block for the ROM.

I've drawn up the decoding logic as below which requires three 74-series logic which gets the job done but somehow feels like it could be reduced:

This if I'm thinking correctly would produce the following truth table which I believe corresponds to my memory map:

Am I  making this more complicated than it needs to be? Could I reduce the memory decoding logic?


texts: Gate delay of carry out C and sum S in ripple carry adder

texts:
Question

How to find the gate delay of carry out \$C_{n}\$ and sum \$S_{n}\$ in ripple carry adder?

I encountered this doubt while going through the book by Carl Hamacher.
It is written as:

Using the implementation indicated in figure (I have attached), \$C_{n−1}\$ is available in \$2(n − 1)\$ gate delays, and \$S_{n−1}\$ is correct one \$XOR\,\,\$ gate delay later. The final carry-out, \$C_{n}\$, is available after \$2n\$ gate delays.

I am completely stuck, how gate delay of carry out \$C_{n}\$ and \$S_{n}\$ is \$2{n}\$ despite carry is using total of 4 gates ans sum only 1 gate?


texts: Does my 7 segment display need a bypass capacitor?

texts:
I have circuit that includes various 74HCxxx series logic chips. Four of the logic lines represent a 4 bit number and I have a 7 segment display used to show the value of that 4 bit number. I use an MC14495 chip to convert from the 4 bits to the 7 segment display lines. This is setup and works fine on a breadboard as a prototype. But I am only clocking it manually by toggling a switch. My worry is that a real version is clocked a 1Mhz and maybe the fast switching 7 segment display will need a bypass capacitor?

(Some of the time the values shown will change so fast at 1Mhz that you will need to be able to make us of it. But there will be times when the value is static for several seconds and hence it does provide a use.)


texts: Back-to-Back Full Page Burst Reads from SDRAM

texts:
I am designing a microcontroller-based video system, and I am considering using SDRAM (~100MHz) for external frame buffer memory. (My microcontroller has plenty of I/O for the data and address busses and control lines, and can issue synchronous bus-wide signals at 100 MHz.)

My question is this: Is it possible to continuously stream data from one or more SDRAM chips using "back-to-back" full page burst reads? (A single full page burst read is 256 words, and I am using one word per pixel. In order to output an entire scanline without interruption, I would need a longer read to accommodate horizontal resolutions greater than 256 pixels.)

For example, consider the Alliance AS4C2M32S 2Mx32bit SDRAM. It has four internal banks of 512K words each. I read through the data sheet (more than once), but it is not clear if I can issue a new bank select just before the end of a full page burst read, followed by a new burst read command, so the output data stream will continue without interruption between the end of the first read to the beginning of the next. If I can chain four of these reads together I should be able to read out 1024 words (pixels) in one go; these will be fed directly to a video DAC.

I am aware of the complexity of implementing DRAM controllers, and I am also aware of other RAM types (such as dual-ported or VRAM) which are obsolete. This question is not about that. I also realize that many MCUs also come with built-in GPUs (such as on the Raspberry Pi platform); nevertheless, I intend to do this "from scratch" for personal reasons.

I simply want to know if anyone with low-level SDRAM experience knows if it is possible to seamlessly chain back-to-back full page burst reads for a continuous stream of data. (I hope to fit in refresh operations during blanking intervals...)


texts:
I'm very new to electronics, this is the most complicated circuit I've tried to create thus far. I'm attempting to step down a 24V DC input to 5V output. I'm skipping the output filter for right now just until I get the buck to work. I know that in a real circuit I'll want the traces to be shorter and the components as close together as possible.

I'm having 2 problems.

The output (red trace from C33) is about 3.5V
I'm unclear if I should have the common ground across the breadboard.

 Sorry if my question is unclear or the image is too cluttered. Component List Below:

Buck Converter
470uF Cap
R1 1.2kO Resistor
R2 3.83kO Resistor
R3 0.33O Resistor
C1 100uF Cap
470pF Cap
Diode
220uH Fixed Inductor

Here's another picture with labels.

Here's the schematic from the datasheet. It's almost exactly what I'm trying to do.

Edit 1
Taking the suggestions of both letsfetz and Yoshimitsu I've made some changes.

I'm now using this inductor
I've moved the diode and rerouted the line coming from pin 2 (see image)

I'm still unclear on if I should connect both ground rails. If I do connect both grounds then I read about 23V on the output. If I do not I read about 4.5 V on the output (for both reading I leave the ground of my multimeter on the J side ground rail).

Edit 2
I'm still trying to figure out why I'm getting about 23V on the output. Below is a screenshot from my oscilloscope. 5v/div & 1ms/div. Reading output of pin 2 with respect to ground rail. I have a load of a LED with a 1K0 pull up resistor. The voltage measured after the LED is about 2.8V

Edit 3
I never figured out why it wasn't working on the breadboard. I created a schematic and board design file in Eagle, sent it to a PCB mill and after soldering all the same components, it works. The only differences are that I added the output filter and a couple LEDs. Wish I knew why the breadboard didn't work.


texts: Resistor on data line between SK6812MINI-E and an MCU

texts: Im getting pretty confused by the resistor that is supposed to be between the DIN of the first SK6812MINI-E and the pin of the MCU. The LEDS are being powered by a 5V 2A power supply (but should only draw 1.045A if my calculations) Now the datasheet says it should be 300-500 ohms, but Im not sure about the power rating. Some people say 10W, some say its not relevant and that I should pick whichever I want in the package I want. Im honestly not really sure.


texts: Need difference between power rails,voltage rail and current rail

texts: Can anyone please explain the difference between power rails , voltage rails and current rails?.How do we choose between these rails?


texts: Implement a data protocol between a smartphone and a MCU via NFC hardware?

texts:
If I'm able to develop a mobile app which is able to use the NFC hardware of a smartphone to write/read through it. And if I have a board containing a MCU and a NFC transponder like the IC from ST Microelectronics M24LR04E which can also make write/read.
Will I be able, for example, to implement a data protocol between an Android app and the MCU through the NFC hardware? Today many people implement data protocols between Android app and MCU by using a bluetooth module. I want to eliminate the bluetooth and communicate them through the NFC hardware.

If you need to know, the MCU I will use have embedded AES and TRNG modules to communicate in a cryptografic form.

Then, is that possible?
Regards.


texts: Moisture Sensitivity Level - More than one chip in sealed bag

texts:
I've purchased three WM8804 MSL 3 chips, which came in a sealed moisture-sensitive package with instructions to mount the chips on the board within 168 hours of the bag being opened. However, it is not possible for me to mount all three of them within that time (I'm doing prototyping right now, not production).

Basically, I know that the first chip will be fine (I'll mount it right after I open the bag). However, the other chips will not necessarilly be mounted 168 hours after opening (there may be problems, I might need to order new boards, etc.).

I don't have the equipment necessary to "bake" the chips, and I'm not doing reflow (just hand soldering). Are there any ways I can prolong the 168 hours (storage techniques, etc.) in order to prevent moisture damage to the unmounted chips? Or is it fine to simply reseal the bag after use?


texts: I don't care how a transistor works, how do I get one to work?

texts:
Every reference I can find on transistors immediately launches into theory-heavy alphabet soup. The above seems also to be assumed knowledge for reading a datasheet. I don't care; I just want to get one to work.

I understand there's some relationship between the current/voltage applied to the base to get a particular current to flow from the collector to the emitter. Which numbers on the datasheet relate to that? If I'm only trying to operate the transistor in "switch" mode, do I really need to care what current I apply to the base or will I be fine just whacking a 1k resistor in between my logic level output and the transistor base?

Is the only difference between an NPN and a PNP transistor which way the current flows when a current is applied to the base?


texts:
I'm using the mp3 player shield from sparkfun and an Arduino UNO. Everything is OK, I formatted my Samsung micro SD cards with FAT, I converted mp3 files with ffmpeg, I load the examples file and modified them a bit, I can play mp3! Great. This is with an earphone.

But.. if I try to connect some 20 euros speakers I hear a strange low-frequences buzz/white noise. Even if the shield is not playing anything.

I'm aware on this pdf on connecting analog output and I've tried to read it but I didn't understand anything.. It explains how to avoid interference caused by long cables but my is not a long cable.. Can it be useful? What can I do?


texts:
I am experimenting with the simple circuit shown below and was wondering how to ensure that the inductor used would handle the inrush current.

My reasoned solution is the following:

I solved for current to Voltage transfer function and applied a step response to get the inrush current (over one second interval), then multiplied by 15 (for 15V input). This gives a peak of around 2.2A which is approximately the current where my bench supply stopped tripping the limiter, so far so good. (ESR was left off of this btw, since it is something like 60mOhm according to the datasheet)

The inductor is rated for 500mA, saturation current is 560mA (datasheet is here). I'm assuming it's heat that kills inductors, so assuming continuous operation at max rating (35C temp rise, according to the datasheet), and internal resistance of 1.7Ohms, that gives 0.425W, or 0.425 J/sec max allowable dissipation.

I then calculated power dissipated in the 1.7Ohms over the 1 second inrush period and integrated. I end up with 0.1408 J, lower than the continuous rating.

However, during inrush the inductor becomes saturated, and I know this generally has a heating effect, which wasn't taken into account in my calculation, and I'm not exactly sure if it is just from the excess heat dissipated in the resistance, or if I need to account for it in some other way.

So my questions:

1) Is this a reasonable way to think about inductor sizing and current handling during inrush, or is there a more common/different/better way?

2) Do I need to take into account any energy dissipated in saturation beyond just the resistance to solve for the total heat dissipation under these conditions?

3) If this is reasonable, would it be applicable to sizing of common-mode chokes at the supply as well? It seems overkill to put in a 2.5A rated CM choke when the system is only drawing a small amount of current.


texts: How to Determine Input Capacitor Value for Peak Power Requirement

texts:
For flyback SMPS, how do we know that our input capacitor value is sufficient for some peak power requirement?

I understand that bigger input capacitor will have more advantage on this peak power. These capacitors are local energy buffers that can quickly supply high currents to the load when it needs it, but how minimum do we need to meet this peak power?

Schematic reference:

Assume that the transformer have enough primary current,

Example if the flyback SMPS is designed at rated power 16W, and it has peak power requirement at 80W, therefore I need to change capacitor value from 47uF to 270uF?

Below are some calculation that I made & some reference from Infineon Design Guide

Is this the correct way?

Please share if you've any better way to do it.

UPDATE : 29-MAY-2020

Thanks to @Verbal Kint for very useful comment.

By referring to some equation in Bulk Capacitor Calculations, C.Basso, I think the estimation of the input capacitor value for certain peak power requirement will be better due to it able to check the minimum bulk valley voltage at low line while delivering 94W.

Below are my new calculations:

Assuming:

By using equation below, I will get 116.4uF

After that, selecting a normalized value for the bulk capacitor. For this example, I choose 150uF, and check value of Vmin when the equation below equal to zero.

Remark: For charge/discharge curve, Vcmin = 84V is based on td = 5.957ms, Vpeak = 120.2V, Cbulk = 150uF

From graph above, during Y=0, Vmin = 68V, and Vbulk = 52V

Based on that, for peak power 94W at 85V minimum voltage input, with 150uF  capacitor, the capacitor DC voltage will discharge from 120V to 68V within 6ms.

Just one new question, how do we relate peak duration, example the peak duration requirement is 100ms into the calculation above?


texts: I´m working on a proyect and i use OrCad/Spice to simulate the op amp that i gone use and my Voltage(output) signal is Constant and my Voltage(Input) is sinusoidal.


texts:
I have ZTE MF112 and Huawei E173 3G modems with this kind of connector on mainboard:

What I want to try is to hook up an external 1.8-2.4GHz to modem. It looks like U.FL male connector to me, but I am not sure.


texts:
What would be the most practical (and preferably cheapest) way to drive 3-4 nixie tubes from an Arduino Uno? I am looking for a setup that, once I make it, will make setting the nixie tube is as easy as a digitalWrite().

Things to consider:

Nixie tubes require high voltage to run
Each tube would take a lot of pins if I had 1 pin per digit
3 tubes is an OK goal - that's a total of 30 different digits to turn on (more than an uno has!)
Cost is a factor

If it is at all possible, it would also be useful being able to put all this into a library, so I could use it anytime with just #include <nixie.h>, however this is not crucial.

EDIT: If you need specifics, I am looking to drive 3 Russian IN-1 tubes from an Arduino Uno R3, and I already have a selection of basic components (resistors etc) so you don't need to include them in the cost.

EDIT: OK, I have an idea. Can you literally just hook 4 Arduino I/O pins per tube up to a 74141, power the 74141 with 100-ish volts, and connect the outputs to the tube? Will this work? If not, why not?

Sorry if I'm missing the point of these IC's completely, but like I said I have been unable to find a tutorial or even an article that outlines how to use these.


texts: Exact (accurate) and cheapest Second Signal Generator circuit

texts:
Sorry, this is my first question.

I want to create a watch (clock) with needles, but I want to create a circuit to generate the second signal (not labview, not software).
I need to know the IC's needed for this and circuit.

Now, I was working long time ago (with TTL), I need something most recent electronic devices.
I was working with BCD and "7 Segment LED", now I don't know ...

I was thinking something like:
http://www.bowdenshobbycircuits.info/page11.htm

But if you have other proposal...


texts: I am supposed to simulate this circuit (regulated power supply 5V), however I am not understanding what's the point of the resistor R. Is it a load resistor? Cause i thought these needed to be before the regulator.


texts:
I picked up an old computer power supply recently and I want to convert it into a bench top variable voltage supply, say 60 V/100 W. It's easy enough to boost the 5 V rail up to 60 V design what is essentially a linear power supply using an op-amp and a FET. See the image below:

Ignore the AD822, I was just using that for simulation. Obviously I would need to use an op-amp that can support a 60 V supply.
The issue is that if I want to drive 1 V at 5 A, the FET would need to be able to dissipate nearly 300 W. Thank you, but I'm not looking to design a heater. This got me thinking that it would be really nice if I could adjust the supply to be ever so slightly higher than the desired output voltage.
Enter the LM5122. See image below:

I'm sure many of you are familiar with switching power supplies, but the controller regulates the output voltage by maintaining a constant voltage at the FB pin. So, what if I were to insert a digital potentiometer in series with Rfbb? I would need to select the input and output capacitors, and the inductor for the worst case scenario. I believe this is sometimes called a "Class H" amplifier. Since this would be a boost configuration, the lowest I could go would be 5 V, but I think I can deal with burning 25 W in a FET in a worst case scenario.
I know I could forget the linear stage altogether and output the power from the switching stage directly, however the linear stage will serve to smooth out some of the ripple and lead to a less noisy output.
Does anyone have any concerns about this design? Thoughts? Comments? Has anyone tried this before? Successes? Failures?

So I checked out the article that Peter Smith recommended (see link below). and it was a neat little circuit indeed. It wasn't exactly what I needed, but it did provide a crucial mechanism by which one could track Vout and provide a supply voltage slightly greater than it. It's very efficient, but also low noise.
So, new plan...

Boost 12 V up to 60 V with a switching regulator.
Buck that down to Vout + 1.4 V with a switching regulator.
Buck that down to Vout with a amp and a FET.

This way, for a 5 A load, the FET should only need to dissipate 7 W or so, regardless of output voltage. See the pics below:
Note that I used the LT8612 as a reference switching buck converter, but any one should work providing that it can support the I and the V.
The only remaining consideration is that Vout only goes down to 400 mV. I believe that there was something in the article for this, but this is a problem for another day.

https://www.analog.com/media/en/technical-documentation/lt-journal-article/LTJournal-V24N2-2014-07.pdf


texts: How to determine BGA land pad diameter for given ball diameter?

texts:
I'm working on a project which requires the use of a CSP package. The product's datasheet provides ball pitch in each axis as X:710um Y:580um and ball diameter as 250um but nothing about the preferred land pad diameter.

How can the pad diameter be worked out from these figures assuming an NSMD land?


texts: What is the type of solder used in a playstation 3 (PS3)? And its melting temperature?

texts:
I have a hot air station and I'm trying to replace the HDMI port on a PS3 (playstation 3). The problem I'm having is trying to melt the solder on the hdmi port. I'm curious to what kind of solder its using as I can't seem to melt it at even 400C. I did test to see if it melted my other solder I got from radio shack and it did in fact melt it.

Why is the solder on these boards so much harder to melt? Is there something extra added to these solder points?


texts: Is cable to resistor also considered a resistor?

texts:
I have a parallel circuit with 50 parallel wires each connected to main cables (+ and -) on top and bottom side of the circuit. I want to calculate the total resistance which I know is R = R1/ total number of parallel wires.

Should I also include main cables in my calculation? If so, should I measure the length of the cable from the first "resistor"? Should I only calculate the main + cable or both?

Thank you!


texts:
I'm trying to interface an Arduino with an eMMC chip to bit-bang it. eMMC uses bidirectional lines, and one of them (CMD) is first used in open-drain mode (for identifying devices on the bus) and then in push-pull mode.

I've inherited a circuit supposed to do that, but even after a few modifications it doesn't seem to work. I got what looked like responses to my commands but they didn't make sense / failed CRC (and since I added a few bypass caps I don't get anything). I think it's because it uses a TXB0108, and the datasheet says it doesn't work in open-drain mode (and I think I understand why).

As I looked for something to replace it I found the LSF0108. I also saw people use chips from the TXS family for pretty much the same application, with pull-ups only on the master side.

I tried to simulate my circuit with ngspice (through Kicad) and SimulIDE, but I can't get something that resembles how the LSF should behave: as a closed switch on LOWs and open if both sides are HIGH (if I understand that correctly). The guide says it's basically two FETS with connected gates, the top one connected to VrefA and VrefB and the bottom one to input/output pins. But I can't find a Spice model, I can't reproduce it (maybe because I don't have the FETs' properties or the real circuit is more complex), and I really don't understand how it's supposed to work.

So, how does the LSF work and how can I simulate it? (A bit of warning: I just spent two weeks reading about transistors and still find them confusing.)

Also, am I making the right choice with this component instead of a TXS? Are they both suitable for my circuit? I'd like to make sure I order the right components, the shipping costs being higher than the parts themselves...

Here's a simplified schematic if it helps (don't mind the BJT, it's for another question).


texts:
I am trying to blink a led as well as switch a motor on/off parallely using attiny44A below is my code:

Pump Controller:

   digitalWrite(pump1, HIGH);
   delay(5000);
   digitalWrite(pump1, LOW);
   digitalWrite(pump2, HIGH);
   delay(5000);

Led Blink:

    digitalWrite(ledB, HIGH);
    delay(500);
    digitalWrite(ledB, LOW);
    delay(500);

How do I make this run paralley together


texts: What affects the current ratings on constant torque pole changing motors?

texts:
Two different motors, one is rated 1.49A on slow speed configuration and 1.43A on high speed. The other motor is rated 6.09A on slow speed and 6.99A on high speed.
These are constant torque pole changing motors. I don't understand why one motor has an inverse speed - current relationship and the other one has a proportional current - speed relationship.

What I know is that if you keep a relatively constant voltage/speed ratio your air gap Flux will be constant, meaning your torque will be constant. I just don't understand why the current ratings aren't inverse on both motors


texts: Relevance of Galvanic Isolation of Boost Converters

texts:
Flyback Boost converters use a transformer and this setup is still referred to as galvanic isolation.

In most use cases, the output voltage is usually orders of magnitude greater than the input, and still at a significant power rating.

Considering that the higher output voltage means that whatever circuitry connected to the output lends to a higher risk of shock (even at low currents).

How does the use of the term galvanic still apply?

(I understand using the term galvanic isolation for step down circuits such as phone chargers; but cannot wrap my head around it for boost converters esp. high power).


texts:
I have a task to present the ESD safety practices in lab and at work in general. I want to make this interesting and for the freshers out of college, I want to let the importance of ESD precautions sink for long time.

I am planning to spoil the devices as a part of demonstration. Question: How can I do this?

The image tells me to start with FETs.. may be a simple timer and a LED connections and a FET. I am open to use other components as well.


texts:
I was told by a lecturer to study the 555 timer in astable mode, I'm pretty confident I know just about everything now except for how the formula for the output high and low time was derived. Things I know:

The high time is the time the capacitor takes to charge
The low time is the time the capacitor takes to discharge

I tried to derive a general formula for both myself:

Q = It = CV = CIR
t = RC
But the formula is:
t = 0.693RC


texts: Resistor values to produce 8 voltage windows into analog pin

texts:
I have 8 Arduino Nanos (at 5V) plugged into a PCB and I would like each to have an ID so that each Nano can choose an I2C address without any clashes, without having to program each differently first, and using only one analog pin. Then, if I swap any of the Nanos around, they will pick up an address based on the resistor value of their location.

For this I think I only need each Nano to see the output of a voltage divider for this purpose, but the threads I've read don't recommend resistor values to use, so I'm not sure what will give accurate readings while limiting current leakage. Can anyone recommend some values to use?

The readings don't need to happen quickly if that allows higher resistor values to be used.

thanks,
Danny


texts:
Does a Y to delta transform for resistors work the same way when inductors a connected in a similar fashion?

simulate this circuit – Schematic created using CircuitLab

I have a load bank that is wired in a Y configuration. I'm given the specks for loading in a delta configuration. I'm trying to figure out if these loads will work.


texts: XTR115 current loop transmitter more steady output

texts:
I'm using a XTR115U in my circuit to make a 4-20mA output. As I found out this IC is a current amplifier based on the below image on the datasheet.

To test this IC, I connected the 2.5V Vref using a 20K resistor to pin2 (Iin). But I have a flicker on the output with a magnititude of 0.01 mA, and on the other hand the circuit is very dependent to tempreture as I heated the 20K resistor the output changed dramaticly.
What is the best practice to make use of this IC?


texts: How do I convert this analog PID to a digital one?

texts:
I want to transform a type III analog PID into a discrete-time one so I can implement it on a PIC18F. The controller is for a buck converter.

When I apply the bilinear transformation to the analog transfer function

\$ s =\dfrac{2}{T}\cdot \dfrac{z-1}{z+1}\$

how much should T be when my switching frequency is 500 kHz and loop bandwidth is 60 kHz?


texts:
In three-phase the 2nd and 3rd phase are offset by about 120 degrees(\$\frac{2\pi}{3}\$ radians). But how is this achieved?

The concept that just each phase is offset by 120 degrees sounds easy but designing a circuit for this looks more difficult.

Does it go back to when the electricity is generated at the power station or done later on in the transmission?

For example each generator is configured to generate one phase slightly later than another?


texts: How does UART know the difference between data bits and start/stop bits?

texts:
I understand that it is common for a UART scheme to use 8N1, meaning 1 start bit, 8 data bits, and 1 stop bit. Something like this:

0xxxxxxxx1

Where 0 is the start bit, the x's are the data, and 1 is the stop bit. In the case of multiple frames being sent back to back continuously, you'd have something like this:

0xxxxxxxx10xxxxxxxx10xxxxxxxx1

My question is: how can the receiver tell the difference between the start/stop bits and data bits? To illustrate this point, suppose that the data byte 0xAA is over and over. This would look like:

01010101010101010101010101010101010101010101010101

I made the start/stop bits bold for emphasis, but it seems to me there really is no way to distinguish these from the data bits.

Sure, if the receiver has had a solid error-free connection to the transmitter since eternity past, then I can see how this wouldn't be a problem. Or if the bytes are not sent back to back then it wouldn't be a problem. But I've worked with 8N1 circuits that were continuously transmitting bytes one after another, and I could disconnect/reconnect the wires mid-transmission and the receiver would always jump right back into receiving correctly. How is this possible?


texts: It makes sense to use an optocoupler with the same ground?

texts:
I've a microcontroller and I want to have some protection for a digital output, but I only have one power source so I was thinking on use a diode to prevent backward currents.

It's reasonable to use an optocoupler for this purpose?
The side effect of inverting the output isn't a issue.

simulate this circuit – Schematic created using CircuitLab


texts:
After 3 days reviewing my PCB layout before going to production, I'm not really sure about it. It would be great if somebody could give me any advice/comments about this crystal unit layout.

DETAILS:
 MCU: Atmega328P-AU
 CLOCK SPEED: 16MHZ

CRYSTAL TYPE: SMD-5032_2P (HERE)

LOAD CAPS: 2 x 22pF

GROUND PLANES: Both 1st and 2nd layer

Sorry if there's something bad in the layout, I'm just 16.

Schematic:

@DanielGiesbrecht:  You mean these vias?


texts: Fob Key Pads Indicate Reception of Correct Key But do not Open

texts:
What is the cause of the following "error" or dysfunction with fob (electronic keychain remote) secured doors:
When swiping the correct key for building doors secured by fobs, sometimes if you swipe your key too fast the fob indicates it has received the swipe by emitting the audible receive key signal (such as a beep) however, the door does not unlock.
Logically speaking, the receive key signal to the user (the beep) should not be emitted unless the fob has in fact received the key. Also, if the fob received an inconclusive swipe, it should not emit the beep to the user. What is happening with fobs in this case. I have observed this with many different fob secured doors on buildings. It appears to be a common signal/communication problem.


texts: Problem with potentiometer in op-amp audio system design

texts:
I have a simple audio setup I am trying to build that consists of an op-amp board (OEP30Wx2), 2 speakers (Dayton Audio ND65-8), a steady 16V power supply (this op-amp requires 16V to drive 8 Ohm speakers at 15W) and a simple aux cable.
First setup was successful, I got clear loud sound coming from my drivers. Then I decided to introduce a 50K potentiometer since I want to build the speaker system into a case with a volume knob (attached to said potentiometer.)
Here is where things got dicey.  The sound was definitely not right, things like voices was completely gone and it almost sounds like when an aux cable is  broken and one channel was dead. I connected the potentiometer in the following manner:

Here is picture of my actual connections:

The first pair or wires (bottom pair in picture) is a screened audio cable that goes to  my aux cable (audio source) that I've stripped the ends of and isolated left, right and ground and soldered it on to the aux cable.
The second pair of wires (top pair in picture) goes from the potentiometer to the op-amp and its connected to INL (left channel input), INR (right channel input) and AGND (audio input ground.) Note that on both wire pairs going to the potentiometer, I took their ground cables to the far left connections (ground connections in the first diagram I showed.)
I'm unsure where I connected the potentiometer incorrectly, and the "Common Ground" connection confuses me - the first cable's ground goes to the potentiometer's bottom connection and the second cable's ground goes to the potentiometer's top connection. Is that right?


texts: What would an acceptable replacement be for a discontinued Motorola HCT174A?

texts:
I am trying to replace a Hex D Flip-Flop on an Amiga A4000 motherboard.  The original chip has the label

HCT174A
XAA346

I believe the datasheet describing this is the MC74HCT174A (though I can't find a reference to the XAA346), however, a BOM for the Amiga Motherboard lists

74HCT174, SOIC package
74HCT174, SM, EIAJ Package (as an subsititue)

When when I search Mouser.com I find 5 possible choices and the TI CD74HCT174M (datasheet) seems like the correct choice, is there anything to keep in mind when sourcing a replacement?


texts: Does an impulse function at t=0 go to infinity, or 1?

texts:
Impulse function is basically the derivative of the step function u(t):

$$
u(t)=
\begin{cases}
0 & \text{if $t<0$} \\
1 & \text{if $t\geq0$}
\end{cases}
$$

I was taught that in laplace domain, if the transfer function $$H(s)=\frac{N(s)}{D(s)}$$ has a higer degree in the numerator than in the denominator, then the circuit is unstable because that would mean $$H(s)=1+\frac{R(s)}{D(s)}$$ and the inverse laplace of 1 is the impulse function, which my professor says goes to infinity.

But what I don't get is why the laplace transform of the impulse function is equal to $$\int^{\infty}_{0}\delta(t)e^{-st}dt=e^{-s\times 0}=1$$


texts: How to stretch high frequency digital signals (e.g., MIDI) into the audio range

texts:
I'm curious about the possibility of sonifying MIDI data, which has a bitrate of 31250.  The range of human hearing extends to about 20kHz, which means that the fastest bits of the signal would lie near the top of this range: not ideal for my purposes.  I envision stretching the signal, and then passing the result to a small speaker.

I'm not sure if there is a more precise term for this operation than "stretching" (I'm not super familiar with digital signal processing).  At any rate, I can provide a concrete example of what I mean:

00101110100001 >> stretch by 2 >> 0000110011111100110000000011

Not unlikely, the resulting sound will seem be rather atonal/noisy, and that's OK by me.  I imagine that I could accomplish this task with Arduino, but I'm wondering about whether this could be done with clever circuit design.  For instance, something akin to using a 4018 divide-by-N counter IC?  I recognize that the 4018 isn't exactly what I'm looking for, since  this acts on a strictly periodic clock signal.

Any ideas?


texts: Electromechanical locks used in a turnstile

texts: I was looking to build a RFID operated turnstile similar to picture below. I will have RFID readers on both ends where the door would open from either end only if the RFID is authenticated on either end. I was wondering what are the type of locks used in these turnstiles which open the turnstiles when an RFID authenticated and then lock these turnstiles and prevent them from moving after a person enters through the turnstile after successful authentication. Are these special locks or some kind of electromagnetic locks ?


texts: Diode N value less than 1 for temperature sweep

texts:
I have seen many manufactures using diodes N<1 for their PSpice model and LTSpice model diodes so I tried to run temperature sweep in LTSpice and PSpice

In LTSpice if N<1 DC sweep eg:1m with .temp it dont provide necessary plot

For Pspice

  .MODEL DB D(N=1m)

with Temperature other than 27C we get error

So I tried to keep N=1036 and tried to match IS accordingly in EXCEL but the overlayed result diode current dont match for N=1m

Is there any other way to match diode drop and current in PSpice of N=1m, So that it can be temperature swept?


texts: Why is mains voltage showing up on my oscilloscope from MagSafe shield?

texts:
I'm theoretically aware of grounding issues that can come up when using an oscilloscope [e.g. as explained in this video], but I can't make sense of this one:

I have a device under test (imagine an Arduino board) plugged into my laptop, which is plugged into the wall via a brand new Apple power supply which has only two pins (no ground). If I connect my probe ground lead to the shield of the device's USB connector, and then probe the device's GND my oscilloscope shows a 152.0V sine wave at 60Hz, offset by -10V!

When I unplug my laptop, this signal goes away – unless I happen to be touching both my laptop and the metal end of its power cord! In fact, my oscilloscope shows this "110VAC" signal when I probe the metal end of the Magsafe adapter.

Why would the outer "ground" of my MagSafe adapter have mains-level VAC on it relative to my oscilloscope's ground? They are plugged into the same outlet — is this expected or could there be something wrong with this building's wiring?

UPDATE: I realized I had a three-prong extension cord handy to swap out for the "duck bill" on this Apple power adapter. When I use that, the AC voltage measured on the outer part of the MagSafe connector goes away. Still disconcerting that it would be there when using the two prong plug, or is it just some sort of harmless low current leakage when connected that way?


texts: Why feedback is activating at more than 4V?

texts:
In this circuit:

I don't get why the current start flowing from more than 4V. I thought was due to threshold, but the same happens with an NPN as M2 or using an BS170. With this last one, everything start an 0.5V early than what you see below. Below is reported the behavior of the schematic above.

Any clue?


texts: Determine whether 5V line has power using 3.3V IC (Atmega 2560) without burning power

texts:
We're using a 3.3V ATMega 2560 and we'd like to test whether a line (actually two lines) have 5V supplied or not, and we'd like to do this using as little power as possible. Are we better off testing intermittently using a P-Channel mosfet, or could we just use a high-value series resistor strait into the pin and not require an active components?

A long battery life and preferably low cost are key! A cheap mosfet won't break the bank though...

Thanks
Danny


texts: what will happen when providing two pull up resistors in same line

texts:
If two pull ups given in a situation one pull is 4.7 K-ohm and other pull up is 10 k-ohm was given to open-drain pin then what will happen? Imagine the open-drain was connecting to an IO pin of an external MCU
In open drain pin's device datasheet it was mentioned that open drain pin as input will handle max of 10 uA. In that case will that 1 mA damage the open drain pin ?  actually there will be current division right (or) will all current enterily flows towards the open-drain pin ?


texts: Is there a good way to test your schematic before buying the parts and building it?

texts: I'm trying to design a BMS that can handle 12 cells, be powered either with a isolated dc-dc converter or the batteries themselves and uses active balancing, but I'm not sure if my design will work:


texts:
I am building a POV LED Globe using ~200 RGB LEDs.

I have three different types I am looking at and have no experience with:

5mm RGB LEDs - Diffused (example)
5mm Straw Hat RGB LEDs - Water Clear (example)
5mm Straw Hat RGB LEDs - Diffused (example)

I have some Water Clear RGB LEDs and I am not pleased with them. The colors don't mix and all the light comes out of the top and almost none out of the sides. I know I can diffuse them myself by sanding or otherwise but for ~200 LEDs it's a lot of work.

For this project I want LEDs that have a wide angle of visibility and an even distribution of light so they have the same color/intensity at any angle on the curved display. The diffused straw hat LEDs seem like the best choice because from what I've read the straw hat design has a higher viewing angle and the diffused shell will mix the colors together better, but without real experience with any of them, I don't know that the best one on paper will be the best choice in reality.

What are the pros and cons of each of these?


texts:
I'm trying to step down 12 volts 3amps to work with a Raspberry Pi.  I'm using the LM2576T-ADJ/NOPB along with the reference schematic/parts shown in the datasheet (100uf, 1000uf, 100uh, and a diode )

When no load is connected, the voltage walks up to 12 volts; when I attached it to a 5v voltage regulator which is in turn hooked to the PI, it walks up to 3.3Volts and stops.

The question is, what part is limiting it to 3.3 volts?


texts: Comparator question for weak sine inputs

texts:
I have the above circuit to convert mV level sines to pulses. It is a working design I just simulated it.

When input sine signal VG1 amplitude is less than around 70mV comparator cannot convert to pulses. When the input sine amplitude is more than 70mV it can successfully convert to pulses. Below are simulation results for 60 and 80mV input cases:

I have 2 questions:

1-)How can I lower the sensitivity. For example to be able to convert pulses even at 10mV without using another op-amp?

2-)What might be the reason for C1, C2 , R3, R4 and R5 and why configured that way?


texts: Why does Camera Serial Interface (CSI-2) have multiple data lanes?

texts: I have been reading through the CSI-2 spec and some controller documentation and I see that it has up to 4 data lanes. If data is transferred on 4 lines at a time then how is it a serial interface anymore? Isn't it a parallel interface now? And how is it different from Camera Parallel Interface?


texts: How to control chip select and Load DAC signals for a DAC chip?

texts:
I have a DAC7643 (Texas Instruments) - 16-Bit, Dual Voltage Output
DIGITAL-TO-ANALOG CONVERTER

I have been mostly unsuccessful with controlling the CS and LDAC signals. I have simulated a circuit for the DAC on MultiSim.

Kindly advise what is going wrong. The pdf has a table on logic level to set for the control signals to get the right output. After numerous valid combinations, the output voltage still remains 0v.


texts:
I found a schematic for a CC/CV buck using the LM2596-ADJ. I was curious if anyone knew exactly what the op-amp  (LM358) is doing, as well as how the potentiometers are adjusting output current and voltage. For reference, pin 2 is a switch output and pin 4 is a feedback input. The link is here:

http://www.mikrocontroller.net/attachment/149248/65_1301577300.gif


texts: DC motor won't spin with PWM unless touched with hand, and other hand touches "ground" from metallic cabinet

texts:
I'm using the common L298N motor driver module with an Arduino Uno to control one  12V DC motor.
The motor will not spin unless I clutch it in my hand and with another part of my body, touch what I guess is reliable ground. Like a metallic cabinet.
It kind of appears that physical contact with the body of the motor "completes" the circuit because I feel a tingle where my body touches the cabinet.
What are the reasons for such a behavior in DC motors? Does this mean my GND connections are not wired correctly? How do I begin troubleshooting this with a multimeter?
I have tested 2 modules to verify if the module itself was defective but I don't think that's the case.


texts: Arduino/Mosfet control of CMOS logic chip

texts:
So I've found a basic composite video "synth" which I'm trying to manipulate with an arduino. The device was originally controlled by NO tact switches between pins on the CMOS MCU, a Signetics SC80C51B (datasheet below).

I've replaced some of the tact buttons with 2N7000G N-channel signal mosfets, which are driven directly from the pins of the arduino UNO (5v).

So far, I've had some success. The arduino can reliably emulate most of the buttons by sending a momentary (~10ms) HIGH to the gates of the fets. However, some of the buttons behave erratically, triggering other buttons, even those which have not been replaced by mosfets.

EDIT: removed confusing example, made unnecessary by schematic.

Now, this leads me to think that the buttons are multiplexed, which makes sense. However, I can't figure why some of them work completely fine and others don't. Logic leads me to think that if the multiplexing were the problem, all of the buttons would behave erratically.

Unfortunately, I don't have a digital scope to capture any of the pulses and investigate further. I suppose I'm just hoping that someone can explain to me how I can better interface with the Signetics chip, or how to better emulate the button presses.

If you need further informations (pin #s, etc), just ask, I'm just not sure what's relevant.

EDIT

I've attatched a photo of the pins as they're hooked up. FETS A, B, C, and "OUT" all work correctly, "REV" and "WIPE" trigger other buttons as well as themselves. FET A's drain does not pass a continuity test between any of the pins on the MCU, but works correctly, don't know what to make of that.

Signetics Datasheet


texts: Is my K-type thermocouple defective, or am I using it wrong?

texts:
I have two K-type thermocouples that look exactly like the one below.  One was sold as good to 800C, and the other was quoted as having a temperature range from 0-400C.  I have been swapping them between a multimeter and PID controller while trying to get control of an electric lead furnace, which consists of a steel pot, resistance heating coil wrapped around it a few times, and an outer shroud.

I have tapped the shroud in a few places to thread the head of the controller's thermocouple tight against the pot.  And I am getting very bad results, using infrared thermometers to check the actual temperature at the contact points.

The thermocouple pressed tightly against the outside of the pot has very high latency, and it never catches up.  E.g., the pot will heat to 400C in two minutes.  The thermocouple will increase its reading more slowly, peak a minute or two after the pot reaches steady temperature, and never indicate much beyond 250C.
If I drop the other thermocouple loosely inside the pot, touching the side, it will react more quickly and get further, but it will still stabilize about 100C lower than the infrared thermometer indicates for its contact point.

Since this occurs with two separate thermocouples (that, for all I can tell, are of identical manufacture) I'm wondering if I am doing something wrong?  For example, is there supposed to be slack between the nut and the head of the thermocouple?  Or are these just poor pieces of equipment and I need to buy something better?


texts: Does the use of PID controller require knowledge of plant's Transfer Function

texts: As simple as that. I assume that you use PID when you do not know the Transfer Function of the system, otherwise you use it and plug it directly in the closed-loop control.


texts: How can I replace this 5565 SRAM with a dual port SRAM?

texts:
I have an existing device (an arcade CPU board) that stores some data in a 5565 64-Kbit SRAM. I want to replace it with a dual-port RAM so I can read the data with a microcontroller. I don't need to write from the second port, only read.

Whatever component I use will have to be compatible with the original - in particular, the game will have to be able to access its port at any time without worrying about contention with the other.

What should I use?


texts: Starting motor for 1 minute after every 2 hours

texts:
My requirement for hydroponic fodder trays, I wants to spray the water in every 2 hours for 1 minute. Can anybody tell me how I can achieve this in lowest budget as wanted to distribute this technic on large scale to farmers.

With the information I have, I need to purchase
Option 1. 555 timer IC and Relay? And please suggest how?
Option 2. Some sort of ready made controller like adriuno? And please suggest how?
Option 3. ???? ? And please suggest how?


texts: In USB, what is the difference between a PHY and a transceiver?

texts:
I understand PHY to be the physical layer of the transceiver protocol stack. At the same time I understand that transceivers are devices that transmit serial data at a very high speed i.e >100Mbps.

What I am not sure about is ICs that have PHY in their title and others that have Transceiver in their title. Here are 2 examples. One is a USB PHY while the other is USB transceiver.

e.g http://www.smsc.com/Products/USB/USB_Transceivers/USB3280/Download and http://www.smsc.com/Products/USB/USB_Transceivers/USB333x/Download

What is the difference between them?


texts: What does a beginner need to know to build a programmable heater based on resistance heating?

texts:
To build a programmable deep fryer, as a learning project for more serious checmical reactors, I need to build a programmable heat source that can be controlled in response to sensor readings and a schedule. I'm a programmer and I have some metalworking skills that I am currently expanding on, but my knowledge on electronics is basic at best.

I'm pretty much in love with induction heating, but I was advised on this question that it might not be the wisest choice to start with, so let's try resistance heating first.


texts:
I plan to build a flashlight powered by 360F 2.7V super capacitor (proposed to be charged to max 2.5V and discharged to min voltage of around 0.6V to increase capacitor life). The EMF generated by the 200 step stepper motor is around 10V peak when rotated at around 300 RPM. I have tried to draw the circuit block diagram.

Is this circuit going to work? Do I need a filter here? What parameters do I need to keep in mind for selection of different components considering the drop across rectifier diodes is between 0.8V to 1.4V?


texts:
Presently, I am reading about different types of transformer. I am stuck on 'spiral core or wound core transformer'. I didn't find any good explanation about it in the textbook I am reading. Searched on the internet in hope to find more detail, but same thing, no good description.

I am providing the text from the book I am reading as follows:

In spiral core, spirals of strip steel are wound through the window of perforated coil. The resultant structure provides continuous magnetic path unobstructed by butt or lap joints hence the path of reluctance is reduced.

I don't understand the words in bold.
It will be helpful if it is possible to provide a picture for better understanding.


texts: reverse engineering a serial protocol with a scope

texts: In lieu of a serial capture device are we able to look at the output of an rs-232 feed and correlate what we see on the scope with ASCII/hex representations (do certain voltages tend to correspond with this character representation or that  character representation? Line feeds and carriage returns come to mind) or are there too many variable to reverse engineer a serial protocol in this manner?


texts: Confused about direction of current in bjt question

texts:
In solution of this question they said that current through 3k and 9k resistors are same...
Here my confusion is
Why Ib of Q3 is zero? Because currents for both resistors are same only when Ib
is zero.
Also base voltage of Q3 is 3V given in solution, but i think that it should be voltage across 9k resistor (which is 9V as per voltage divider)


texts:
Context:
I am programming a flight controller for an autonomous drone. I want it to be able to hover in place so I am working on a PID controller for the throttle to keep vertical velocity at 0. (Assume the drone is level with respect to gravity as I have a separate PID controller for that).

Since I am dealing with velocity rather than acceleration but my only sensor is an IMU, I am trying to integrate the acceleration data to get velocity. However, when I do this it introduces a lot of drift, and I have tried several ways of correcting for the drift but none of them have produced useable results.

My question is this:
Can I use a lowpass filter on the acceleration data instead of an integrator and would it eliminate drift? I don't care about the accuracy of the result because I am finding the gains of the PID controller experimentally. As long as it is precise and does not drift it should work.


texts:
I'm working with 8x8x8 single color led cube.(8x8 anode cols and 8 cathode rows)

I've done soldering and I have lots of 74HC595N chips. Of course you know one chip can deal with 8 anode lead of LED. So, I will use 8 74HC595s for that. This may work for 64 different OUTPUTs.

Then, what about cathode? Can I use 74HC595 for INPUT?(I think I can use just 8 different pins on Arduino or RPI)

One more question please, I have 5V 2A adapter. Can I use this for cube without any other components?

Thanks in advance and please understand lack of my knowledge about electronics.


texts: Is there an existing type of voltage regulator that holds a desired/specified voltage below the Vin?

texts: I'd like a relatively efficient way to regulate a voltage at say 6.5 volts less than the Vin to my circuit. The circuit requires a Vin range of 7 to 60 VDC. So for example if the Vin was 45 VDC the voltage regulator would output 38.5 VDC and if the Vin dropped to 12 the voltage regulator would output 5.5VDC. Ideally this regulator would be able to supply a maximum continuous current of say 150 mA but would not use that much when the circuit wasn't using it... Perhaps this device (and/or circuit) is common and I just need help with the jargon/terminology.


texts:
I want to make a small clock using Nixie tubes (for the cool/retro/steampunk look of them), I have some basic knowledge of electronics, but I have never done anything with more than 12V DC and ~10A. I saw that Nixie tubes are usually using 3mA at 180V in order to make the Neon glow and I am concerned with the safety concerns.

Because I do not want to hurt myself with a shock of 180V caused by a mistake due to my poor experience with high voltage, I wonder if some indicator tubes that look like Nixie ones are functioning in low voltage/current ?

I know no Nixie tubes at low voltage can not exist because the gas needs to be excited to produce light, thus, the "look like" is very important.


texts: Circuit behaves erratically when using a long cable

texts:
I've got a circuit, it is a dimmer that a friend of mine designed, it is providing energy to 15 meters of 3528 led strips.

I'm using a 12v 5A power supply, and as long as I connect the PS directly to the circuit, it works just fine.

However, when I connect the PS to a cable (1.5 meters long) and then I connect that cable to the circuit, it starts to behave erratically, sometimes it doesn't even start, other times it reach full power and then it shuts down.

I have the circuit details if you need them, just wanted to quickly check out if there is something obvious that I'm not taking into account, since I have barely basic knowledge of electronics. My brother in law (who designed the circuit) is on vacations unfortunately, so I can't consult with him.

Ant help is appreciated.

EDIT:


texts:
Quick couple of questions, I am designing my first PCB and want to have a few boards prototyped with OSH Park.

For a board I will be manually soldering components to, will I need to include a tCream layer or is this for automated soldering only?

And, do hobbyists generally make the surface mount pads a little larger than the components data sheet specifies, to help with soldering? Are there any other tips/tricks a first timer might like to know to make life easier?

And, for milled slots, i.e. two holes for a USB receptacle to mount to the board, do I need to include a note for these or is the data on the 'holes' layer sufficient?

Thanks in advance


texts: Problem Placing Polygon Pour on Board Altium 17.1

texts:
I'm laying out a two-layer PCB. I've routed all the signals, including power and ground. I like to add a ground plane on both layers by placing polygon pours.

I'm having trouble getting Altium to pour the polygon, and I'm not sure why. I've placed a circular keep-out layer, convert it to polygon and tried pouring, but no polygon had formed.

I thought it was a clearance issue, since the traces on my board are pretty crowded, but after changing the clearance value, I still can't place the pour. I've even changed the air gap value for the polygon pour. I have no idea why at this point.

Attached is the picture of the board, and the link to the .PcbDoc file too.

Edit: I forgot to mention that I kept getting the error Modified Polygon: Polygon Not Repour After Edit

https://drive.google.com/open?id=1aem0g2JZH2BVgYKAJDZJzsjJOqdnDD1W


texts: RF Switch or Splitter to test multiple DUT

texts:
The task is to test multiple DUT's (sequentially) for Transmitter & Receiver testing in multiple unlicensed frequency bands supported by the DUT. I could connect a single RF Signal Generator to 2 DUT's either using a 2:1 Power Splitter  or an SPDT RF Switch.

I understand that Port Isolation for Power Splitter is usually lower (~30dB?) compared to an RF Switch (~90dB?) between the 2 output ports. But I am curious (assuming all the ports are well terminated with 50 ohms attenuators), which would be a preferred way to test a particular DUT at a time?

I also understand the RF Switch + Controller assembly could be expensive, but I am trying to understand the application differences between the 2, accuracy-wise, or understand does the comparison even make sense.

The setup is fairly straigh forward, VSA/VSG connected to 2 to 1 splitter/combiner OR SPDT switch which is connected to 2 DUTs. Its a 2.4/5 GHz 802.11 abgn signal, testing Rx signal at -70 dBm sensitivity PER test and Tx signal at 20 dBm power level to measure Power & EVM. Again this will sequential test, where DUT1 gets tested first followed by DUT2.


texts: Impact on the battery life of a wireless mouse based on a using practice

texts: While using a wireless mouse having alkaline batteries, does it matter to the life of batteries, at what distance from my computer I use it? I mean, if I use the wireless mouse from a far distance (within transmitter-receiver's recognisable range) will it drain the batteries more?


texts: What type of USB Protocol for Datalogger

texts: I am attempting to create a USB datalogger and would like to first start with creating a program that transmits Hello World over USB not using some kind of CDC communication.  I am trying to figure out what device class I should use.  Am I right for trying to set it up as an HID device?  FYI, I plan on using the PIC32 USB Starter kit for this.


texts: 3 Phase Voltage Inverter for BLDC motor. N mosfet getting hot. Why?

texts:
I am making a bldc motor and attached is my 3 phase current driver circuit. A,B,C represents the phases of the motor (Y winded). The sockets behing the bjt's go into arduino micro-controller. The bjt's used are NPN 2n3904.

Top mosfets are P Channel's (FQP7P06) and bottom mosfets are N Channel's (IRF610PBF). My state machine is currently using no PWM (digitalWrite is being used).

Q. My N-channel's are really hot even with a 0.8Amps and motor is not working. I have checked my statemachine and circuit connections several times but I am not sure where I am going wrong. My hall sensors are positioned 60 degrees apart. VCC=6-12V depending on the current intake.

The link below was used as a reference for energizing the mosfets.

mosfet usage and p vs n channel

Your help would be much appreciated.


texts: JK Flip-Flop Counter: How to reset a counter?

texts:
I currently have a 3-bit asyncronous counter (built using J-K flip flops) that continuously counts up. However, I am struggling to figure out how to reset the counter to 0 when an input (Reset) is true.
According to the J-K flip-flop truth table, when J = 0 and K = 1, Q = 0. Thus, I feed the clock signal into the K inputs of the flip-flop generating the least significant bit but I feed into the J input the opposite of the Reset input (chaining a NOT gate to it). Below is my asyncronous 3-bit counter:

However, when Reset is activated, the counter freezes instead of being reset to 0. This seems strange, considering that I am following the boolean algebraic properties of the J-K flip-flop.


texts: LM318 Voltage Follower Self-oscillation and Output Noise

texts:
I've been trying to tame an LM318 opamp in order to replace the LM741 in a circuit because I need to buffer a higher frequency sine wave than the LM741 likes (1Mhz).
The datasheet shows the following example circuit right on page 1:

Ok, so I build this up, and am feeding a 200kHz signal at 0.6V peak-to-peak offset to a small, positive value, with a +5 and -5V rail:

However, instead of buffering the voltage, the amplifier starts to self-oscillate:

Not what was supposed to happen, so I decided to solder the circuit to perfboard, but much to my disappointment with the same result.
I thought maybe adding a resistor before the oscilloscope at the output would help so as to not drive a largely capacitive load, but that made no measurable difference
After lots of research I came across a post that recommended decoupling pin 1 and 8 of the opamp with a tiny capacitor (I used 5pf, but tried other values, larger didn't have a visible effect), and it seemed to tame the beast a bit, but the output was still distorted. Note that this is not mentioned anywhere in the datasheet. however, in the internal diagram on page 15 there seems to be C3 (28pF) connected across pins 1 & 8 internally, so not sure why a tiny 5pF would make a difference here.

This sure isn't by design, so my question is basically, what am I doing wrong in using this device and how can I fix this?
Is it not suitable for this purpose and I should consider a different chip?


texts: Lorentz force opposing mechanical input to a generator?

texts:
When comparing between an electric motor, and a generator. I find them being quite similar. I can use and motor as a generator and vice versa.

What's confusing is the principle, the Lorentz force applied in the case of a motor, it causes the torque & acceleration of the armature. Simultaneously, causes the motional back-emf on the motor when it reaches high speeds.

What about the case of a generator? Certainly there is emf due to the Lorentz force, and when there is a load connected to a generator, current flows inside that magnetic field,is there a Lorentz force due to that generated current flow that opposes the applied mechanical input that induced the voltage of the generator?


texts: Is it possible to distinguish between a TRS from headphone or from MP3?

texts:
Is it possible to distinguish between a TRS plug from a headphone or from an MP3 player?

As we know, the output from an MP3 player has a signal unlike the output from a headphone.

What I want to do is basically the following:

What options do I have on this?


texts: What are the advantages of larger SMD pads at the ends of a SOIC land pattern?

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I was looking at this NXP TSSOP8 footprint and was wondering why the end pads were 0.600 mm, and the non-end pads were 0.450 mm.

What advantages does this have?


texts: How does speaker in "ROBOCOPP B A S U Ealarm SOS Personal Alarm" works?

texts:
I was working on a project which required producing a sound with more than 125 DBs...then I found this device in market which claims of producing 130DBs although to my knowledge it produces around 110DBs od sound still pretty high for a small speaker. I'm attaching a video link related to the device.

https://www.youtube.com/watch?v=8daQrb4scmc

Can some please explain to me how such a small speaker is able to produce such loud sound?


texts: A have a circuit for which I have parameterized some of its resistors with the .STEP command. Consequently, I have many different graphs when I simulate the circuit. I would like to know if it was possible to put a constraint on the graphs that would tell the simulation which one can be plotted (like for example : V(vout) <= 100mV)?


texts:
I'm an electrical engineering student in my summer training. My adviser is busy, so my training is self-learning, I'm supposed to learn RF circuits, ADS, and finally, design an amplifier do some cool things.

To reach my trainee goal designing an amplifier in RF, can you recommend sources(slides/videos/book/Udemy-course) in amplifiers design?


texts: SEPIC converter current waveform question

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I am designing a SEPIC converter, powered by 3.7 V Li-Ion cell. Frequency 500kHz, Transformer 10uH per side, 1:1 ratio. Ferrite material #87. Output to be variable by adjusting duty cycle.

It has good efficiency over 80% at 7W. But when I push it to the design goal of 10W, efficiency drops too much. Tested with a load of 10 ohms and 39 ohms. When duty cycle adjusted to increase output using either load, the the transformer core and MOSFET heat up quickly going over 7W. Looking at the MOSFET drain with a current transformer, I was expecting to see a saturating core with current spiking, or rising drain-source voltage. But no. Observing the drain current wave on the scope, the inductive charge ramp rises as expected with increased output current. As the voltage to the load is increased by increasing the duty cycle, the inductor current ramp flattens out, and even the slope reverses! What is the cause?


texts: Selection of fastest speed grade of Zynq in Vivado

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I would like to make an implementation in Vivado using a Zynq z7030. I see that there are about 32 possible zynq's available. I would like to know which one of them is the fastest (if that can be said in generally). I suppose that the fastest ones are the ones ending on -3 but still then I have as options
xc7z030fbv484-3, xc7z030fbv676-3, xc7z030ffg676-3, xc7z030ffv676-3 and so  on. Which one of them will be the fastest or do I have to simulate all of them in order to know that?

Kind regards


texts: The circuit below takes the signal from a current transformer, depicted as I1, convert it to voltage through R9 and go to the second order filter U1. I want to add an offset to the current transformer signal so that it swings around Vcc/2 instead of crossing the zero point, so I can process the signal with an ADC. Is it safe to use a voltage divider with a voltage follower as shown? The circuit does not have specific components values, but would the concept idea work?