texts: Assembler basic question : translation to machine code

texts:
How does a assembler (at very basic level) work in translation of Assembly language to machine code ?

[What my understanding  is that when a Programme is written it is written in text and then assembler converts these "texts" into bits which computer understands . So for example if I wrote MOV A, B  this will be saved in memory with the help of "keyboard"( in 0s & 1s which are basically electrical pulses). Now as these  saved bits will be containing bits corresponding to  alphabets like 'M' ,'O' 'V' (The ASCII code) so and so on .Now what assembler will do is to compare these bits stored in the memory ( which are corresponding to the "texts") to the bits already stored in "assembler". So the text bits ( MOV…)  will match to some of these assembler bits ( out of lots of bit groups  which are related to other key words like MVI ,ADD ) and as a result of these comparisons it will give "opcode" relating to “MOV” text. Am  I right or is this a wrong way of thinking? ]


texts: Combining LDOs in an effort to increase current

texts:
Is there any way to combine 2 (or more) similar LDOs with fixed output voltage so the total output current would be increased?
Buying another LDO is possible but I have a large stock of 1A LDOs and I need 3A.


texts: I am soldering LED strips together but I am in a location without access to an electrical outlet.  I am using a battery powered soldering iron but it doesn't get very hot compared to my home soldering iron.  I am having a tough time melting the solder with it and getting it to stick to the pads.  Can you guys recommend a solder that melts at a low temperature?  I have also tried a butane powered iron but it broke after only a few uses so I would prefer to try a new solder before changing the iron.


texts:
I'm using the Microchip 16-bit 28-pin starter board and the USB communication with the PC keeps breaking.

There are two microprocessors on the board. The application processor communicates to the USB processor via UART. The USB processor is configured as a CDC class USB device and shows up in device manager as a serial port.

The device enumerates ok and the data being transmitted from the PC to the application processor ok. The application processor is responding to the USB processor, but the response never gets to the PC.

I know the UART communications between the two processors is working ok because I'm using a BusBee to monitor the UART. I did not write the code for the USB processor (that came from Microchip). It's worked before, but I can't seem to get it working again.

Is there a tool or anything I can use to debug the USB end points on the PC?

Something like wireshark, but for USB?

Has anyone else used the 16-bit starter kit from Microchip and had similar problems?


texts: Are Cal Kit (SOLT) definitions unique by serial number?

texts:
I have an E5071B Network Analyzer and 85033E cal kit.
One of the standards is broken now and needs to be replaced. This is the Male OPEN standard (Part number 85033-60018).

Question:
Will the definition files (that come on the floppy disk, and are now installed in my VNA) still be valid after I replace the broken OPEN standard? Basically, are the definition files specific to each individual kit per serial number or is it just one set of definition files that works for all 85033E kits?


texts: Analog Switch, switch a voltage that is ~0.5v higher than VCC

texts:
I've been looking into different Analog Switch ICs and it seems they always allow a switching voltage between GND-VCC. Now the voltage I want to switch comes from a different source than VCC. Generally it should be aprox. the same as VCC but the exact voltage is always unkown and can be between 4.5-5.5v. Vcc is rated to be 5v.
All switches I found are rated for a max. VCC of 5.5v or higher.

Now does it pose a problem if my switching voltage is slightly higher than VCC in some cases?
I'm a bit confused that VCC is the limit when these ICs are just using MOSFETs internally.

The grounds of both voltage source are of course connected.


texts: What is the meaning of "half bit" in this context?

texts:
In RS-232 specification, the stop bits can be 1, 1.5 or 2 stop bits...I wonder how it's possible to have half a bit?

Also some ADC math uses 0.5bit precision in the IC specifications/datasheet. Can someone elaborate in this subject?


texts: 4 Channel Relay Module Set to LOW activates relay?

texts: I seems that my 4 channel relay module is acting the opposite of how I thought it should act. When I do use the Arduino "digitalWrite(relay, HIGH);" essentially turning power on to the relay, the relay switch is open. When I write "digitalWrite(relay, LOW);", it closes. How is that correct? I thought when you energized the coil, the switched closed to complete the circuit, not the other way around.


texts:
I have an anemometer reed switch connected to a uC with a 10K pull-up. I then have a RC filter to debounce around 500Hz. This is the case:

A fairly old anemometer connected to my board powers the reed switch @3V3. I cant seem to get a "low" seen on the uC pin. It seems to stay ON at about 2V5 when magnetised.
Now there is another board that powers the reed switch @5V. The system can see a "low" on its input. I believe this has to do with the DC characteristics of the uC and registers 2V5 as a "low" wheres on a 3V3 this isnt true.
If I get a new anemometer then my system can actually see a "low" and count pulses.

Does this have to do with the aging of the reed switch? The 5V system might see a pulse but for how long?


texts: How to find the Fourier transform when it is in the form of \$\frac j\pi\$ [\$\frac{1}{(t-3)^2-1}+\frac{1}{(t+3)^2-1}\$]

texts: So as the title suggests, I can compute Fourier transforms in basic forms using the known properties. But how would one attempt to do this? How do I compute the integral? Or is there a pattern/pair that I could use? The equation is as follows x(t)= \$\frac j\pi\$ [\$\frac{1}{(t-3)^2-1}+\frac{1}{(t+3)^2-1}\$]


texts: Why is the outlet ground voltage different from grounded Macbook voltage

texts:
Measuring on A/C with a digital voltmeter:

Measurement One
I connect the ground lead to earth on a 3-prong plug,
And hold the other lead with my thumb and forefinger,
And observe that I register approximately 53 +/ 2 mV.
In this configuration I conclude that my body electrical potential compared to ground is about 53 mV.

Measurement Two
Same as above, but now my body is also grounded to earth.
I now observe that I register 1 +/ 1 mV.
In this configuration I conclude that my body electrical potential is about the same as earth.

Measurement Three
I measure my body vs. ground with a hand on my Macbook Pro with aluminum case and connected to power through a 3 prong outlet.
I observe 38 +/ 2 mV.

Measurement Four
Macbook case vs. ground yields 5 +/- 1 mV.

Hypothesis:
I had thought that by touching my MacBook Pro, my body would have the earth voltage (basically something like 2-5 mV).

Instead, even though the case is sitting at 5 mV, when I touch it, my body voltage (53 mV) drops to only 38 mV instead of the hypothesized 2-5 mV.

Why is this happening?

And is my experiment any good to begin with?
I had hypothesized that working on my Macbook was equivalent to touching the grounding strip at removing voltage across my body. This seems to not be true.

Thank you in advance for any insight and education.


texts: HDMI for Jetson Nano contradictions in guides

texts:
For my drone, I want to develop a custom Jetson carrier board with minimal required interfaces. For quick debugging, I would like to add an HDMI port on the PCB. However, I’m not familiar with HDMI and I found some contradictions between guides.
In most guides, it’s written the impedance of the trace should be 100 Ohm. I found some pretty easy schematics examples

However, in the Jetson Nano design guide, there are more required elements as these capacitors and Rs resistors, which I do not completely understand the purpose…
Schematic:

At the end, there is this figure, which tells us to have 500 Ohm impedance traces where all segments should be 100 Ohm :/
Schematic:

I can blindly reproduce the carrier board but I would like to understand better what I’m going to do.
Thx in advance!


texts: AVR external crystal not working with UART

texts:
So I have an ATmega328P with a 14.7456MHz external crystal, full-swing settings, and I'm trying to talk to my mac via UART and an FTDI friend-type device.

If I connect AVR Tx to AVR Rx, then all bytes come through perfectly (I can view it on some 7-set displays). If I connect FTDI Rx to FTDI Tx, then all bytes come through perfectly (viewed on Arduino serial monitor). The baud rates of both devices are the same.

However, when I connect them together ...

Serial monitor gets data (scroll bar appears and starts scrolling across), but no characters are displayed. It's as if they are all spaces (I send 'a', or an arbitrary 8 bit number). If I select half the baud rate, then weird characters appear, but not what I send.

AVR receives characters (receive interrupt fires), but what it receives is either 0, or the same number (eg. 173, but it seems rather random) for any character I send.

I've googled and googled, and have found no solution to this. Any ideas? Help on this is much appreciated. (hopefully I've provided enough information)


texts: Determining Blanking for HDMI Transmitter

texts:
I am working on a project which produces a video output over an HDMI connector. The driver I am using is the Texas Instruments TFP410PAP.

The image I am attempting to display is WVGA, 800 x 480 pixels. I designed my board to configure the driver via the I2C bus which is controlled by a small MSP430 microcontroller. The I2C registers allow me to enable and configure a built-in data-enable (DE) signal in the driver IC which controls the blanking at the top, bottom, left, and right of the screen. There are six registers that control this: DE_DLY (left border width), DE_CNT (image width), H_RES (screen width), DE_TOP (top border height), DE_LIN (image height), and V_RES (screen height). DE_CNT and DE_LIN are easy - that would be the 800 x 480 pixels of the desired image. However, the issue has to do with determining the other values. When a monitor is plugged in to my board, the driver chip does not know what its resolution is, so selecting values for DE_DLY, H_RES, DE_TOP, and V_RES seems tricky.

I know that some monitors will automatically detect the input resolution and adjust their settings accordingly, but in any case how would I determine appropriate values for the four aforementioned configuration registers? Obviously my goal would be to center the displayed image in the screen and make it as large as possible (i.e. minimize blanking time), but I am not sure if there is a limit to that (in other words, is there a minimum required blanking time?). Furthermore, if the monitor has a different aspect ratio than the input signal (which is likely), how will it handle the transmitted WVGA image?

Below is a graphic from page 16 of the datasheet to illustrate the purpose of the different values:


texts: PWM vs ESC for speed control for Arduino quadcopter

texts:
I'm from a computer programming background, but I'm interested in combining hardware with software, so I'm playing around with Arduino.

Currently going through things on things needed to build a quadcopter. And I came across ESC and PWM. The way I think is that both control the rpm of the motor, so whats the difference of the two?

I googled a bit about it, and I got something related to brushed and brushless motor, without diving in too deep, I understand there is difference in the design of the two motors. But the question remains can I use PWM to build a quadcopter or do I have to use ESC?


texts: Use a OR wired with diodes to control the gate of a PMOSFET

texts:
If a have an OR wired with collector outputs to control the turn ON and turn OFF of a PMOSFET, shall I use a pull up resitor in the source input of the PMOSFET? Does the design need a pull down in the PMOSFET gate?

With this design the MOSFET is always turn ON, even when the gate is 5V, how is possible?

UPDATE:
I have replaced the input connected to the schottky diode by an open collector NPN and added a pull up between the source and the gate and a resistor in the input of the gate but the circuit doesn't work. The intention is to do a OR gate, so when one input is high the PMOSFET turns down.


texts:
I'm looking at powering an embedded board PC using a 12V PSU and I'm having some trouble due to inrush current.  The board draws 5A for about 1ms on startup and unfortunately this trips my PSU's overcurrent protection.  I did some research online and it looks like I can get an inrush current limiter from Digikey (http://www.digikey.com/product-search/en/circuit-protection/inrush-current-limiters-icl/656273).

My question is will these inrush current limiters work for a DC output, or is there a better way around this?  I've only seen people talk about using the inrush limiters at the input side of AC-DC converters, although some places mention it can be used in DC scenarios, but with no examples.

If these inrush current limiters will work for my purpose, do I just pick one with a steady state max current that's lower than my PSU's maximum output, and pick one with an R@25c value that gives me an acceptable current limit at 12V?


texts: I have a Non-Inverting amplifier with single supply which doesn't have offset-null pins, is there any method for external Offset-Null without the need negative supply.


texts: Arduino UNO R3. IDE Error-Not in sync. TX shorted to 5v?

texts:
I have (had?) an Arduino UNO Rev 3.

While uploading sketches Arduino IDE reports this error
avrdude: stk500_getsync(): not in sync: resp=0x00

I'm not sure when or why it stopped working. It would be either while I was messing with the ambient light setup which was working perfectly. I could have accidentally shorted something.

Here is what I have tried so far using a multimeter.

Tested using the multimeter and the 5v pins reads 4.75v.
3.3v pin reads 3.4v
Removed the ATMEGA328PU from the socket before testing further
from this point
TX Pin reads 4.8v
Multimeter shows no continuity between 5v pin and TX pin

It looks like the TX pin is shorted to the 5v pin.
Is there anything I can do to fix this?

Or while trying this.

I powered the ECG circuit from the Arduino's 5v pin. I tried to upload a blank sketch (Bare Minimum from the examples) thats when this problem popped up.

Tried the loopback test

Connected GND to RESET ... and RX to TX..
Removed the ATMEGA328
from the socket and connected RX to TX

In both cases when I use the serial monitor there is no echo.
When I type something in serial monitor and hit enter the RX LED on the Arduino UNO blinks but the TX LED does not blink.

Same happens while uploading sketches.
The LED on pin 13 is always powered up.
When I upload a sketch PIN13 led blinks around 4-5 times. LED on 13 turns off. then the RX blinks 3 times. LED on 13 turns and stays ON again and thats it.

Are there any other tests I could do to determine the problem?
Should I consider my Arduino UNO dead?

P.S. I have no background in electrical engineering but referring to the EAGLE schematics found on the link below can anyone tell me what I should test for using a multimeter?
http://arduino.cc/en/Main/arduinoBoardUno


texts: Optical encoder from printer always has about 1.60V on output

texts: I have disassembled HP DeskJet 3000 j310a. I've removed paper feeder encoder board (shown on image). The problem is that when I connected it to 3V3 supply (it has builtin resistor on LED side), it always has 1.60-1.63V on output A or B no matter whether the gap is cutted or not. I'm sure sensor is not damaged because the printer was fully working (was a donor for a damaged j310a printer in better condition). What might it be?


texts: How to deal with LFBGA217 package when building prototype boards by hand

texts:
I am involved in a project in which I need to create a few prototype boards that will use the AT91SAM9G20B-CU processor in the LFBGA217_J package.

Because this is a fine pitch BGA package, I'm not sure how to go about building prototypes that can be populated by hand. One thought I had was to have a PCB
manufacturer create a simple "breakout" or adapter board that contains the BGA package and brings out the pins in some manner that will allow the board to be fairly easily soldered onto a main board that has the memory and I/O ports etc. Basically I'm trying to find a way to have a CPU board manufactured that converts the BGA package into a form that is more friendly to use in prototype boards.

I have the ability to solder fine pitch SMT packages with legs, but I can't deal with BGA's. I realize that once the prototype board is proven I can have the boards manufactured and assembled by a PCB fab house that can deal with BGA's, and that is what I eventually plan to do.

Currently I'm laying out my boards using Eagle CAD 6. Do you have any recommendations or advice for me?


texts: How does the Arduino compare to PIC and AVR for serious learners

texts:
I'm trying to get into microcontrollers, but as you might guess, choosing the first microcontroller to start with is a difficult task due to the many great choices available.

I have studied electronics (both analog and digital), computer organization and I'm presently reading a book on computer architecture.

What better way to cement my understanding than having a real microcontroller at hand. I have been tempted to get Arduino due to its popularity and its purported simplicity. However, just like programming in something like C# and not necessarily knowing what happens behind the scenes, I'm apprehensive that with Arduino, I'll only been using it like C# without understanding how the architecture works which is what I'm hoping to learn.

So, in short, am I wrong in my above assessments of the Arduino above?, and how does the Arduino compare in terms of understanding how embedded systems work to other microcontrollers from the PIC and AVR families.

Thanks


texts: Total phase inductance of three phase reactor

texts:
Consider a three phase  reactor (inductor) using E-I or E-E laminations with phase winding on each limbs. Now inductance of R phase is given by:

Lr=Lrr+Mry+Mrb

Lrr: Self inductance of R-phase
Mry: Mutual inductance between R and Y phase
Mrb: Mutual inductance between R and B phase.

When such inductance is excited with three phase supply Mry=Mrb=-0.5*Lrr. Hence total inductance will be zero.

This means three phase reactor does not offer any inductance?


texts:
I apologize if this is not really an EE question, but it seemed most appropriate. I am considering the following application.

Object is 3000m far away and emits a sound of 94 dBSPL at 0.5m, I, therefore, expect it to be 18.44dB loud at 3000m.

1) Using a microphone with 80dB S/N ratio and -24dB sensitivity. I should be able to hear it (albeit lost in ambient noise). Correct?
(eg https://www.digikey.com/product-detail/en/pui-audio-inc/AOM-5024L-HD-R/668-1596-ND/7898328)

2) My sensors are 0.5m away from each other. if the source of noise is exactly in front of one sensor the time difference of arrival would be around 0.12 uS meaning, that to meet the Nyquist sampling theorem I would need to sample to audio at least 16.5Msps, in order to be able to at least measure the time difference, more, if I would require higher degree of accuracy.
(eg. https://www.tme.eu/cz/details/ad9280arsz/prevodniky-a-d-integrovane-obvody/analog-devices/)

Does that sound reasonable? Or am I missing something?


texts: Current Sense Amplifier and Voltage Comparator in Same Pacakge

texts:
I am in need of sensing the current in a circuit and cutting off power when current exceeds a threshold which should be about 2A. It seems that everything I've read recommends using separate "current sense amplifier" and "voltage comparator" packages but I would think that this need is so common that someone would manufacture a device that does both in the same package. Board space is limited and I don't need to access the intermediate analog signal between the two devices. I have already tried using just a voltage comparator but it doesn't seem to be sensitive enough by itself to detect the small voltage difference across the current sense resistor.

The device needs to operate with a 12VDC supply. I am setting absolute max voltage to about 13.5VDC so the device should be rated for more than 15VDC.


texts: In MIPS Instruction set, why do we sign extend the immediate data instead of zero extend in I type instructions?

texts:
Recently I was reading the "Computer Organization and Design" Book By Patterson and Hennessy, and I came across the question that in order to make the immediate data 32 bit in Immediate type instructions(generally load/store), we sign extend it, but why we do not zero extend it instead?

thanks in advanced


texts:
I've got a trouble with this filter:

I tried calculating transfer function from four-pole matrix, but can't handle it :(
Any help much appreciated.
That shaggy drawed element near U1 source is coil. Sorry for my drawing.

What I've done so far (I think it is wrong):


texts: What are the display parameters for a TFT LCD?

texts:
I want to use this display with a system on module running Linux. I need to configure the device tree below with the parameters for the display so it will work properly. A description of these parameters can be found here.
/* ETM070080BDH6 display (7inch) */
            timing_wvga: 800x480 {
                clock-frequency = <33260000>;
                hactive = <800>;
                vactive = <480>;
                hback-porch = <88>;
                hfront-porch = <40>;
                vback-porch = <33>;
                vfront-porch = <10>;
                hsync-len = <128>;
                vsync-len = <2>;

                de-active = <1>;
                hsync-active = <0>;
                vsync-active = <0>;
                pixelclk-active = <1>;
            };

The problem is that I cannot identify the parameters correctly and some of them I think aren't mentioned in the datasheet. I searched for documentation regarding these parameters, but I found them with different notations and got confused.
Does anybody know what are the parameters requested by the device tree? Also, what values should I put if they aren't given in the datasheet?


texts: Coupled DC/DC-modules - correct input filtering

texts:
According to the support from TracoPower I use two THN-30WI modules (±15V) in conjunction as shown below (without each C1 and C2) to produce ±30V.

This works but I get a lot of noise.

The application note explains how to filter one module according to EN55022 Class B:

I would like to apply that filter to my two-module-setup. How do I place capacitors C4 and C5, when -Vout, +Vout and COM are at completely different voltages than in a single-module-setup? Or is that irrelevant and do I still place them across (-Vout and -Vin) and (+Vout and +Vin)?

Thank you!


texts:
I am new to electronics, with minimal circuit knowledge, and I am trying to build something that does the following:

simulate this circuit – Schematic created using CircuitLab

I have a power cable that is outputting 12 V and about 10A.  My goal is to design a relay into that cable, that will cut the power supply if the arduino supplies 0 V and will do nothing to it if the arduino supplies 5V.  I have been told to look into solid state relays, but they are expensive and I was wondering if I could just use a simple SPST.  My only issue is that the arduino can only supply ~100 mA, and I want the device to not fry when it has 10 A on it.


texts: Is an arrangement of solenoid valves the only way to achieve fluid redirection?

texts:
Not sure if this fits in the charter of this site. If not, pointer to another stack-exchange site would be great.

For a rain-water harvesting system that I am designing for my house, I need to be able to control the flow of water out from/into a reservoir in 3-4 different directions, i.e. a case of multiple inputs and outputs.

I am only aware of solenoid valves as the mechanism, that I could control via a microcontroller, to achieve the desired flow-path -- including having a water-pump on/off. Are there other mechanisms to achieve such goals (of course, under microcontroller supervision) ?


texts:
I have a question about power a portable LED light source. I understand the various ways to power an LED array but my question is more about the best practical approach.  I have created a portable “LED Light Bar”/“Book Light” for lighting sheet music. In order to spread out the light for a more even cast with less shadows, I have created the following layout:

12 LEDs, each LED has the following specs: 6.1 V / 117 lm / 150 mA / 4000 K / 90 CRI (Luminus Devices MP-3030-2100-40-90), that are paralleled and spaced 10 mm from each other on a 10 mm x 200 mm aluminum PCB.

I would like to power this with a 2S LiPo (7.4 V – 8.4 V) supply. I wanted the supply to be as small, simple and fail-proof as possible. The light will only be needed for about 30 min per use so battery efficiency is not a concern. I was thinking about using just a single resistor or a single AL5809 (SOD123 120 mA CCS AL5809-120P1-7) on each of the 12 LEDs. I was leaning a little more toward the AL5809 since the level of light would remain more constant as the battery voltage changes.

One other thought I had in order to not use resistors or CCS on each LED, was just to power the LED board through a 5.6 V linear regulator, which is below the 6.1 V drop of the LED.

Again the goal is for the smallest, simplest, fail-safe, portable LED light source that produces a good quality of light for 30 min at a time.


texts: can an AC 110V motor controller be used with a bridge rectifier work as a DC motor controller

texts: I was going to buy a DC brushed motor controller but would an AC power supply, with heat sink and fan, connected to a bridge rectifier work? The dc motor is 48VDC 300W 5 amps.


texts: Fixed Point Division in verilog for Spartan 6

texts:
I am developing a core on Spartan 6 which needs to do divisions like
1/6,2/4 etc... so the values are always between 0 and 1. As I dont need the precision of floating point I am want to use a fixed point divider as division is costly.
I found some dividers on opencores.org but all of them can computer normal division problems like 4/2,8/4 etc... well but cannot do 1/6 kind of operations. Can anyone point to a suitable divider for my application

Thank You


texts: what is the impact of a resistor when it is connected to the output terminal of an inverting amplifier. Does it make any difference to the output voltage or to the gain?


texts: Are there tips and tricks for SOM for place power pin and reduce PCB layers?

texts:
I'm developing a SOM with microcontroller, SDRAM and flash.
Following the documentation that I found on the web and that made available by the component manufacturers (such as this: STM32MP1 Series DDR memory
routing guidelines - it is for microcontrollers and DDR but the suggestions are still valid), creating a PCB with 8 levels.

My questions are:

Are there any tips or tricks to follow to reduce the number of levels that are hardly found published in the literature?
Is there a rule to follow to arrange the ground and power pins of the SOM (for example, a ground line or power supply every "n" pins)?

Thanks in advance.


texts: Need help identifying a strange symbol in a wiring diagram

texts:
I have this simple wiring diagram for an old tractor, and there are some symbols that look almost like diodes, but not quite. I have highlighted most of them in red in the attached image. Do these symbols represent diodes, or something else?

The text in the wiring diagram is in Norwegian, but do the following substitutions, and you'll understand most of it:

lys is light
bryter is switch
hoved is main


texts:
I'm trying to find and plot the CMRR of the following circuit:

I'm getting zero for common mode gain, that gives an infinite CMRR for the circuit. When I followed normal feedback laws, I get (2/SRC)+1 as the differential gain.


texts: I have a new wired door bell which has two source of power i.e. from AA batteries and AC grid. On connecting the bell to bell switch, the bell rings continuosly even though the switch is not pressed. This was not the case with my old bell which gets power from AC grid alone. What could be wrong here?


texts: What is the purpose of 5, 9, 15, and 20 Volt rails in the USB PD spec?

texts:
The reason for 5 Volts is obvious, baseline compatibility with USB protocol, lowest common denominator.  Higher voltage options were required to deliver the wattage required by modern devices.

Allowing a PD charger to deliver a continuously variable voltage range, for example passing through vehicle supply voltage, or LiPo pack voltage, seems like a simple efficient method of achieving that goal.  Yet, my reading of the USB PD spec seems to prohibit that option.

First, is my understanding correct, that such pass through via USB Type C PD 3.0 is a violation of the spec?
Please suggest any way(within PD 3.0 spec, perhaps an alt mode) to pass vehicle supply voltage(always < 20v), current limited to 5A, from a charger/OBDII device I am designing, via USB Type C full featured cable, to an Android device I am also designing.

Second, why are 4 fixed voltage levels required to be provided by charger instead of a continuous range(as in Qualcomm Quick Charge)?

Third, what are the advantages for a charger to supply each of those specific voltages, 9, 15, 20v.

As I understand it, maximum wattage 100W was chosen due to international safety requirements.

Any answer that states the reason for the voltages is to maintain safe current within existing cables must also explain how this is relevant given that PD is only allowed over USB Type C cables and that 5A is allowed at 20V, but only 3A at the lower voltages over the same cable.


texts: Clock Oscillator - Topology and PCB Layout recommendations

texts:
I'm designing one of my first layouts and I've read a lot of articles and StackExchange questions about guidelines and recommendations.

It's a university project realized by another student that I had to correct for some major mistakes. I've corrected those and now I'm trying to improve the layout in general. This extra work is not really required, but anyway I'm trying to make things how they should be done to learn more.

Here is how I've made the layout for an oscillator NBXDDA016, connected to a DDS AD9958.

C18 and C19 are 100nF, required by the DDS for input AC coupling.
R25 and R26 are 50 Ohm terminator resistances placed there I suppose because they where present in an example of the oscillator datasheet.
C_TA13 is a 10uF decoupling capacitor.
R25, R26, C18 and C19 are 0805 standard package.

Are R25 and R26 terminator resistances really necessary? (see Update 1)
Is 10uF for C_TA13 too high value for its purpose?
Assuming the schematic is right, I feel like I've done a terrible job with the layout. I've tried to connect all supply and ground pins together before going to the ground and power planes with vias only at one point. Do you see any problems with this layout?
Should I connect the oscillator ground with the DDS ground on the top layer and then connect to the ground plane only at the thermal pad of the DDS?

UPDATE 1

The DDS has an input impedance of 1500 Ohm and an internal bias of 1.15V (hence the AC coupling). Should I terminate the line before the capacitors even if there is an impedance mismatch at the receiver?
This Application Note pictures a really worring scenario caused by paralleling decoupling capacitors, especially if very far away in value (decades like in the suggestion from The Photon and in other common answers). Should I be really concerned and carefully simulate the real capacitors in parallel, or is that A.N. exaggerating?
I'm insisting with the "single via to the ground and power planes, just after decoupling" concept, because I'm trying to avoid the center-fed patch antenna that Olin Lathrop always points out in his answers. This way I try to keep fast switching currents away from the ground plane. I understand that using multiple vias for the oscillator pins and terminator resistors would defeat the purpose. Is it correct?


texts: What sampling rate is needed for demodulating and decoding GPS signal data?

texts: I just got a software-defined radio (SDR) and am trying to record GPS frequency (L1 1575.42 MHz).  I understand that GPS is modulated using Binary Phase Shift Keying.  I also read about the Nyquist rate which says that I would need to sample the signal at 1575.42 * 2 MHz (3150.84 MHz).  Is it true that I would need to sample at 3150.84 MHz to be able to correctly demodulate the GPS signal?  My SDR maxes out at 2000MHz sample rate.  I'm quite a beginner to RF electronics so may be confusing things.  Thanks in advance.


texts:
I have some design equations from a text book which are designed to realised a KHN filter. However, when implemented and simulated, the values shown do not realise the design. A gain of 20 dB should be expected in the pass band. I have a feeling it is to do with the large input resistor (R1), and the dividing effect between R1, R2 and R3 meaning the signal is attenuated before even reaching the filter/amplification stage. However, would have assumed this would have been accounted for in design equations.
See page 164, https://gctjaipur.files.wordpress.com/2015/08/continuous-time-active-filter-design.pdf

The circuit parameters are seen below:

X is the denominator of equation 4.93c


texts: Why GSM module connects with same apn for different operator?

texts:
I'm using SIM868 in one of the GPS tracker that is being developed.
HTTP protocol is used in sending data to the server.I have tried this with SIM cards of 2 network operations,Vodafone and Airtel.
AT+SAPBR=3,1,"APN","www"
is the command I use to set the apn of the network, in here the apn of Vodafone is "www" and the apn of Airtel is "airtelgprs.com". However it is found that Airtel network also works with the apn of Vodafone and vice-versa. Both networks are able to connect and send data to the server(verified in the server side as well).
How is it happening? Is apn not a mandatory parameter in connecting to internet?
Regards,
Joe


texts:
I am designing a power supply card using V7805-2000 for 12V to 5V conversion. In the datasheet on page number 6 they have a recommended input filter and output filter circuit. For the inductor they have mentioned value between 10uH to 47uH.
The input to the V7805 will be 12V@2A. I used 0805 footprint for the inductor in input and output path.
I am unable to find the part number for matching the recommended value(10uH to 47uH) in 0805 package at the input and output current rates of 2A. I want to use an inductor current rated twice the needed current rating to be on the safer side.
What happens if I use this Inductor in both input and output path?


texts: How do power generators generate AC at a constant frequency?

texts:
As far as I know, alternating current is generated at power plants by converting rotational energy to electricity. The frequency of the AC depends on the rotational frequency of the rotor. In USA, the frequency must be 60 Hz, correct me if I'm wrong.

However, I don't know how power plants can maintain such constant frequency. This might be easier in nuclear or thermal plants, but how about in case of wind turbines, where the wind speed isn't constant, and hence, the turbines can't spin at the constant rate?

I tried looking around, and I found this Reddit discussion. I however do not trust Reddit as a reliable source, so I wish to get a reliable answer here.

So, in short, how does a generator generate constant frequency despite inconsistencies in the energy source (such as irregular wind flows)?


texts:
https://github.com/hzeller/rpi-rgb-led-matrix/tree/master/adapter/active-3

This board is for level shifting 3.3v RPi GPIO output to 5v. There are 3 outputs; half of the pins of each output are unique to that output and the other half are common outputs.

Of course, the unique outputs are separately buffered; however, some of the common output pins share one buffer vs. other common output pins being separately buffered - particularly:

  The strobe, OE and clock signals are separately buffered for each connector.

Is there any benefit to separately buffering a common pin for each output?


texts: BeagleBone Black HDMI to VGA converter creating problem with the display

texts:
I recently bought a BBB and have started setting the initial environment before I start some actual developments. Since, my monitor has a VGA input, I bought a HDMI to VGA converter adapter to interface my BBB to the monitor. However, I am facing a problem i.e.

Problem Scenario : I power my new BBB from an external 5Vdc/1A adapter and then connect the BBB to the monitor using the HDMI to VGA converter. After booting the BBB, the display comes on the monitor for a few minutes and then, some how the display goes off and the screen blacks out (I presume it is to do with the HDMI to VGA adapter).

Has anyone using BBB comer across this problem?, If so could you please detail me on what is creating this issue and how to resolve it. Thank you all in advance!

Between to add, when it was tested with my friends BBB, it worked perfectly fine, but with mine it was giving this problem!.

Regards
~VD


texts: ATmega128 output compare normal mode. Generating a waveform with ISR

texts:
So here are specifications:
-prescaler of 8
-Channel A
-pulse_width is determined by user defined degrees (converted to clock ticks)
-pulse_period is 40000 clock ticks (20ms)
-Normal mode
-Timer3

So we have a move_servo(unsigned degrees) where all it does is convert the degrees to clock ticks and store it in pulse_width. Ok no problem.

Then we need ISR(TIMER3_COMPA_vect). This interrupt is supposed to actually generate the waveform where pulse_width would be high and (pulse_period-pulse_width) would be low (so total pulse length is 20ms).

Now I am not quite understanding how the OCR3A register works. My thinking for the ISR was to have a flag variable so that the first time ISR goes off, it sends pulse_width out of OCR3A, then set flag, next time it goes off it sends off pulse_period-pulse_width (which will be low and is the wait time between each movement of servo) and will set flag to 0 again.

But writing to OCR3A will move servo right? Will my plan work in the toggle mode for normal mode? So every other trip into the ISR sends out the "wait time" which is low so it doesn't move servo?

My question is basically am I on the right track? Or if not can anyone help me understand how to generate a random lengthed pulse followed by a "wait time" waveform in normal mode?

This is ATmega128 again fyi

THANKS!!


texts: How to switch 1000w AC load with minimal heat?

texts:
I am trying to heat a 1000w heating element with 120VAC. I am currently using a thermocouple and SSR to regulate the temperature, but the SSR is getting too hot at full power even with a heatsink. In open air, it's fine, but once it's in an enclosed, even with vents, there isn't enough cooling. I want to avoid moving parts so I didn't want to use a relay or a fan; is there an alternative?

Edit: Since people mentioned zero-crossing, I am switching at the zero-cross points and while I say it was an SSR, it wasn't a prebuilt one, but one I made with a BTA-16 600B triac, 4n25, and moc3021. It was based on an AC dimmer module sold by RobotDyn since I wanted to originally use PSM to control heat output, but now I simply need the AC load to switch on or off and I'm not sure if there is a better way to do it.


texts: Use a device in the board that is not listed in the schematic in Eagle

texts:
I am making the design of a PCB. The problem is that I need to use a device that is not listed in the schematic from a library that I downloaded. The next image shows how is not listed:

But it is in the board:

The problem comes when I try to place that device in the board since I get the next message:

I don't understand how I can backnotate this operation in the schematic if I don't have the symbol listed. Please help


texts: How to handle duty cycle below deadtime in 2- and 3-level inverters

texts:
When programming a pwm for a 2-lvl inverter what would be the suggested strategy for a duty cycle close to 0% or 100%, meaning when I cannot guarantee for dead time. What would cause less distortion limiting the duty cycle to 1/99% or setting bridges to always on/off?

Same question for a 3-lvl inverter.

From my guess in a 2-lvl I should set them to always on/off to archive over-modulation, in 3-lvl inverters (this might also be affected by the topology) I would clamp the duty cycle to 1/99% (anpc). Am I right with my guesses or is there a better way to handle this?

Info: I’m talking about grid connected inverters.


texts: Why is the LM386N-4 power rated @ 32Ω load, when the other variants are rated @ 8Ω? How can I find an appropriate speaker?

texts:
I'm trying to build an LM386 amplifier, but when looking at the datasheet to select the appropriate chip, I noticed the LM386N-4's power rating is based on a 32\$\Omega\$ load, while the -1 and -3 variants are all rated based on an 8\$\Omega\$ load. Why is that variant rated on a different load?

The only speakers I can find at my chosen suppliers (DigiKey or Mouser, which seem to be the only two that have all the other parts I'm looking for) that also will fit the enclosure I'm using and have power ratings within the LM386's range are all 8\$\Omega\$ speakers -- how do I figure out what the power output of the -4 variant would be with an 8\$\Omega\$ load, and would I need to do anything to make it work?

Lastly, I'm trying to get the most power possible, so the 1W of the -4 variant is of course appealing... but I note that the -4, despite having a minimum supply voltage of 5V is also rated at 1W based on \$V_s\$ of 16V. Since I plan on using an existing 6V supply, will I get less actual power from the -4 variant than I would by using the -3 (whose 700mW power rating is based on \$V_s\$=9V)? My instinct says the power would be something like \$\frac{6V}{16V}\times1000mW=375mW\$, versus \$\frac{6V}{9V}\times700mW\approx467mW\$.

What confuses me further is that the performance characteristics graphs (which I can barely make heads or tails of in the first place) don't seem to be different between any of the variants. Are they really all the same?


texts: How to disconnect 3.7V battery when USB is connected (boost)

texts:
I am developing a circuit which enables me to charge a lithium battery and boost the output voltage up to 5V for a microcontroller. My boost converter is the MT3608, and the charging circuit is the TP4056 board.

Everything is working well, but I would like to disconnect the battery when the USB is connected, in such a way as the boost module doesn’t receive any power supply, and so, the microcontroller would work thanks to the USB port, but not through the boost, in order to reduce the global consumption.

I’m following this schematic, which allow me to select between the USB or battery, but I would like to disconnect the battery when the USB port is connected, and therefore the boost module won’t work.

“USB o Fuente”: It is the USB connector.
“Circuito cargador”: It is a charging circuit like the TP4056 board.
“Circuito aplicacion”: It’s my load, a microcontroller in my case.
“Canal P”: It means a common P-channel MOSFET.

I would really appreciate it if someone could show me a schematic that solves my problem.


texts: LDR, LDRD and STR instructions with immediate offset in ARM Cortex-M3

texts:
The Cortex™-M3 Devices Generic User Guide explains the instruction LDRD R8, R9, [R3, #0x20] as "Load R8 from a word 8 bytes above the address in R3, and load R9 from a word 9 bytes above the address in R3". I would like to ask why 0x20 equals to 8 bytes and not 32 bytes?
The guide explains the instruction LDRNE R2, [R5, #960]! as "Loads (conditionally) R2 from a word 960 bytes above the address in R5, and increments R5 by 960". Is the value or the address of R2 updated? Is the value or address of R5 incremented?
The guide explains the instruction STRH R3, [R4], #4 as "Store R3 as halfword data into address in R4, then increment R4 by 4". Is the value or address of R4 incremented?


texts: How to change a sum of produts using AND and OR gates to make it only use XOR gates?

texts:
I have the SOP (Sum of Products) equation: F = ¬A¬BC + A¬BC + A¬B¬C + ABC, which is the sum output of a full adder.

Could someone please help me and show me how by using Boolean algebra i can change this SOP expression to use only XOR gates.

In table below CIN is C the from formula of F above and Sum is result of F.

$$
\begin{array}{c|c|c|c|c}
\text{A} & \text{B} & C_{IN} & C_{OUT} & \text{Sum} \\
\hline
0 & 0 & 0 & 0 & 0 \\
0 & 0 & 1 & 0 & 1 \\
0 & 1 & 0 & 0 & 1 \\
0 & 1 & 1 & 1 & 0 \\
1 & 0 & 0 & 0 & 1 \\
1 & 0 & 1 & 1 & 0 \\
1 & 1 & 0 & 1 & 0 \\
1 & 1 & 1 & 1 & 1 \\
\end{array}
$$


texts: How are PCBs with castellated pins arranged in a panel?

texts:
Can anyone please describe to me how PCBs with castellated pins are arranged in a panel. My understanding is that castellated pins are formed by drilling the edge of a PCB then plating, similar to a normal via process (except the result is a plated semi circle hole, like in the image attached).
Does the castellation process occur after panelization? If the PCB requires cutting the edge before plating, how are these boards arranged in panel that uses either mouse bites or V-scoring for breaking the board off of the panel? Are the areas around the castellated pins routed instead?


texts: Energy stored in capacitors connected in series

texts:
I am confused with calculating total energy stored in capacitors connected in series.
To calculate a energy stored in a single capacitor in terms of joules is C(V*V)/2. I want to connect 2.5V 500Farad capacitance of 20 capacitors in series to a 48 Volt source.  so Total energy stored is equal to
500(48*48)/2 or
20(500(2.5*2.5)/2)?
Which one is correct?


texts: Dual Mosfet Not Gate Getting Very Hot, Critique Circuit

texts:
I have put together this circuit from parts I had lying around, It is to invert a normally closed momentary switch to behave like a normally open. The switch is for a car and toggles a tail light.

Even though the operation is correct the N-Channel is getting very hot, (too hot to touch) worst when the switch is open.

Can you help with this ? Thank you

simulate this circuit – Schematic created using CircuitLab

(R1 is to act as pulldown)


texts: Calculate the time constant for a RC circuit

texts: The switch S has been closed for a long time, and the it is opened. I want to calculate the time constant for the RC circuit below. I don't know how to tackle this problem, is the time constant for an RC circuit always RC, no matter how the circuit looks? If yes, is R and C the equivalent resistans and capacitance one gets when reducing the circuit to one containing a resistor and capacitor in series?


texts:
I'm reading this DAC datasheet. The last page (p. 32) gives certain of the chip's dimensions, some in units of "BSC SQ".

What does BSC SQ mean? Is it standard to express sizes in BSC SQ?


texts:
Possible Duplicate:
  Can we build capacitors on a PCB board?

I have learnt that a capacitor is really just parallel plates. I guess I could use a stripboard as a capacitor by putting links at each end but for a normal 0.1" stripboard like the below is there a formula depending on length and how many elements are across each other? While it seems I couldn't make a large capacitor maybe doing that would be handy for some smaller value, like I see in some small RF bugs?


texts:
I have BASYS3 board which outputs 3.3 V, however my sensor (pir sensor) works with 5v. I also have a 5v supplier but I'm not sure how to connect these 3. I don't want to damage my BASYS3 as well so I'm reluctant to try anything. How can I connect these 3 on my breadboard? Thanks.
Edit: This is what I'd like to do basically:

But the sensor does not work with Basys3's 3.3v output. Normally it does not work when I try to connect vcc and ground pins to the 5v power supply and the output pin to the fpga.
datasheet for my power supply: https://pdf.direnc.net/upload/3-3v-5v-breadboard-guc-karti-datasheet.pdf
datasheet for pir sensor: https://www.mpja.com/download/31227sc.pdf
datasheet for basys3 fpga board: https://reference.digilentinc.com/_media/basys3:basys3_rm.pdf


texts:
I'm trying to perform esr calculations of this capacitor(1uF):
https://alconelectronics.com/wp-content/uploads/2020/06/KP-6-JUNE-2019.pdf
to do that I need to know dissipation factor and at the bottom of the first page there is a dissipation factor-frequency graph, I'm going to use cap. at 60kHz and I choose dissipation factor as 10^-4 because the value is not clear.
When I calculated the "esr = dissipation factor / 2pif*C"
esr=0.00026 Ohms in my situation which is too small in my opinion.
and when I calculate esr zero frequency: "1 / 2piR*C"
fesrzero= more than 600MHz which look weird to me.
Am I doing the calculations right, I mean the values are unfamiliar to me and I'm not sure about it
source: https://forum.digikey.com/t/calculating-capacitor-esr-from-tan/2633


texts: What should I do with multiple 5V to 3.3V voltage regulators?

texts: I'm trying to put a PN532 breakout board, BLE "shield" daughterboard, and a PIC microcontroller all onto one board.  The PN532 breakout board has an ADP121 (5V to 3.3V) regulator, the BLE breakout has a XC6204 (5V to 3.3V regulator), and I also have an AZ1117T (5V to 3.3V) regulator for a level shifter and a RS232 transceiver chip.  I'm curious about what is usually done with multiple regulators with the same input and output voltage?  Should I cascade them, or choose the best one and eliminate the rest?


texts:
I'm looking to design a high current low voltage power supply that goes beyond my limited circuit knowledge. I have plenty of experience putting circuits together, but not so much on the design side.
What I Want
Input: 120v AC at 60Hz (US Wall outlet)
Output: 3.7V (I can deal with 4 if that makes a difference) up to 10A DC. The loads are going to be small, less than 2 Ohm.
I could probably hack this together with a transformer, full wave bridge and a capacitor but here's the part I'm having trouble with: I want 4 outputs that can be, but aren't necessarily, all operating simultaneously.
My Thoughts
The output would be easy enough to wire 4 outputs in parallel to meet the same 3.7v/10A requirement for a total current of 40A if I understand correctly. What I'm not sure about is being able to run, for instance, 2 of the 4, and not get 3.7v and 20A in each. So some way to limit the current in each line is needed.
Generally, I'm lost apart from the simple circuit I described above. Any direction is greatly appreciated. Thanks!


texts: Get negative control voltage for a AS3310 chip

texts:
I'm trying to use a AS3310 chip to generate an envelope from a trigger/gate signal.

The AS3310 expects for the ADR (attack/decay/release) control voltage 0 to -5V - for the S (Sustain) 0 to +5V

I have a power supply of +12V/-12V/+5V sharing the same Ground. So where or how would I get the 0 to -5V from? Would I need to use an inverting op-amp? Is there a more simple solution?

Datasheet for AS3310: http://www.uk-electronic.de/PDF/AS3310.pdf


texts: Is nodal analysis should be applied only when circuit containing current sources..? Or otherwise we have to use source transformation.. When any voltage source is present in the circuit..?


texts: Calculating the cut off frequency of a electronic filter

texts:
I've the following circuit:

I know that the transfer function is given by:
$$\mathscr{H}\left(\text{s}\right)=\frac{1}{1+sb_1+s^2b_2+s^3b_3}\tag1$$
Now, in this post they say that I can find the cut off frequency by finding:
$$\left|\mathscr{H}\left(\omega j\right)\right|=\frac{1}{\sqrt{2}}\cdot\left|\mathscr{H}\left(0 j\right)\right|\tag2$$

Question: so in my example I found that (when all the components have a value of \$1\$):
$$\omega_0\approx0.335005\tag3$$
Is that correct?


texts: Why is this LTC4010 charging circuit resetting?

texts:
I have designed the following circuit based around the LTC4010 battery charger IC.

This circuit is essentially a direct copy of an example circuit from the datasheet.

The target battery is an 18V 1.5Ah 15 cell NiCd cordless drill battery.

I've built it and it's exhibiting strange behaviour that I've been unable to debug, explain or fix.

When a 24V DC source and battery are connected to their respective terminals, the following sequence repeats:

ready and charge LEDs illuminate for ~2ms
fault LED illuminates for ~2.5us

Occasionally the ready/charge LEDs will remain on for 2-4 seconds before the fault LED comes on. From this I believe the IC attempts to start charging, detects a fault, stops and restarts.

My two main observations are:

The datasheet says that any fault state should latch until power is removed, unless the fault occurred due to an over-temperature condition. I don't believe this to be the case. I am using a 10K resistor to GND in place of a thermistor, as per the datasheet. There is a 68n filter capacitor in parallel that is not on the above schematic. There is a steady 1.41V on the VTEMP pin. The IC itself is not warm or hot when touched.
The IC does not appear to be producing any switching waveform on BGATE (for the N-channel FET). I believe this to be because the charger is operating in soft-start mode until it restarts.

Everything else looks sensible, as far as I can ascertain.

TGATE is producing a 550kHz PWM waveform to drive Q1
Vcell is 1.28V, which is the correct per-cell voltage and within the IC's requirements.
I have replaced the IC and both FETs. At no point did the behaviour change.
I'm not a professional PCB designer, but I believe the layout to be sensible in terms of component placement, routing, track widths etc. I can post additional pictures if it would help.

I am at a loss to explain the behaviour that I am seeing. Why is the IC going into fault and resetting?

I know that "please debug my entire circuit for me" questions are slightly frowned upon. I hope I've done enough debugging of my own to help.


texts: Best practice for implementing bare metal or lightweight OS flash file system?

texts:
I am looking at flash devices that are available for rewriteable data storage, and it's clear that they need either some sort of translation layer for an overlying file system (such as FAT) or a specific type of filesystem designed for them (such as JFFS2).

Examples:

Cypress S25FL032P
Microchip SST25VF080B

This seems like such a common thing, but I'm not seeing a lot of resources (specifically on the stm32 platform) for dealing with the flash issues of write-only by page, wear leveling, and bad block monitoring.

It seems like a system like JFFS2 would take care of a lot of that, but it doesn't really seem to be used much outside the Linux ecosystem. What are some of the more common ways to deal with this in a leaner OS environment?

One highly-desirable feature is fault tolerance. For example, if the power is removed during certain operations, FAT can be corrupted. A good solution should be journaled or something similar.

(Note: "Write your own" is a highly obvious and undesirable answer)


texts: How to Wire 7-lead Fan Motor for 3-speed Honeywell HT-380BPC Table Fan

texts:
I have a 3-speed Honeywell fan that stopped turning on when pressing the momentary switch that toggles Low, Med, High, Off modes. I opened it up hoping to find an obvious issue, but didn't see anything. At this point, I'd be fine bypassing the speed-control function, electronics, and just wire up the fan motor to one-speed when plugged in, but I can't figure out the motor wiring.

The motor has 3 short leads: Black, Grey, White, and 4 long leads: Black, Brown, Yellow Red.

The circuit board has the following connections: COM, ACN, ACL, Low, Med, High

AC Outlet, Hot - Motor, Short Black
ACL - Long Black Lead on Motor
ACN - AC Outlet, Neutral
COM - Motor White Lead & Grey Lead (but with 3 uF 250V Capacitor in-between)
Low - Brown
Med - Yellow
High - Red

The speed connections use triacs, and they all tie back to ACN, and ACN is tied to COM with a 7N241K varistor in-between. COM is tied to White & Grey Motor Leads, so I'm not sure how to modify the circuit to permanently enable one of the speeds and discard the other speeds.

I'm not sure if I need to do anything with the connection from the motor to ACL, or if that's just for powering the board... ACL and COM is connected with a fuse in-between (fuse looks good).

Thanks for your help.


texts:
I'd like to design a simple device that uses a microcontroller (in my case a TI Tiva C Series Launchpad) and a relay to drive a load, then monitor whether the load is actually drawing any current.  The load will draw about 5-10 A at 12 VDC.  What is a good method to determining if the load is actually drawing any current so I can use that as feedback into my microcontroller for other functions?  What electronic components would be used?

I'm essentially trying to duplicate how my car knows if I have a failed headlight.  If I flip the switch to the headlights, a signal to an ECU that then commands a relay to close.  If the relay closes, but the lights don't come on, I get an indication on my dashboard info panel (not a dummy light, but a text readout; in other words, the indication comes via the ECU).  The only wires going to my headlights are two power wires (one each for high and low beams) and a common return/ground.


texts: user data generator and user data partner receiver for gtp transceiver

texts:
I want to use gtp transceiver of Artix7 xc7a200t to send and receive Ethernet data, so the transceiver is in full duplex and framed. The reference clock of the transceiver is 200 MHtz.

I want to send my Ethernet packets with line rate of 3 Gbps. First i wanted to use the Aurora Logicore but now i want to use 7 Series FPGA Transceiver Wizard.

In the Xilinx HSSIO Solution Center - Design Assistant Transceiver Design Implementation, they said and i quote:" Replace the frame_gen module with a user data generator, and replace the frame_check with a user data pattern receiver."

I do not no how to replace these modules. I want help to write user data generator and user data partner receiver.

Is there any one who can help me?


texts: Does the second schematic sheet title block need all the same information as the first sheet. To me it seems kind of redundant to keep the signoffs and proprietary statement...


texts: LTSpice Operational Integrator not Working

texts:
I'm fairly new to LTSpice and I'm having a hard time making this circuit to work. So I'm making an Operational Integrator but my Output signal doesn't seem to match my predictions.

If I'm not mistaken Voltage at node Va should be zero since the Operational Amplifier is in a negative feed back configuration.
I'm using the Universal Operational Amplifier and I was wondering if maybe the parameters of the Op Amps where the cause of this unusual signal at Va which in turn effects the Vout.

EDIT:
Here are some more detailed images relating to my confusion.
I understand that the resistors and the capacitors are unusually non ideal for practical use but I just wanted to know why the voltage across the input terminals differ by so much.


texts: Should I insulate between 2 PCB's when SMT joining them together?

texts:
I have designed a circuit board (5v, .02 amp max draw, UART and I2C comms) for an electronics project with many surface mounted components, which I have built and SMT from a house in China. When the board with mounted components comes back to me, I then join a mass-produced SMD bluetooth module (BLE) to the board using hand-soldering technique. I have shown the back of the board below, the top has all of the factory-mounted components.
I have traces running underneath the BLE mount area on the back, both power and signal, as well as a significant portion of the ground plane.
It is at this point which my electrical "ghost" seems to always appear. The board seems to always short out at some point after this, where I can either smell ozone (sometimes even see the smoke), or serial output kookiness appears. Being that I have only done this 10-15 times because I only have so many boards to test, I know that randomness may be at play, as far as timing of the problem.
I am experienced at SMD hand-soldering, have all the right equipment, so I know that I'm not doing anything wrong on that front. For the past 2 days I have experimented with putting a piece of electrical tape insulation between the BLE module and the main board before I join them together, and it SEEMS like the problem has disappeared (again wary of randomness). I wrote some code to track serial output and have not had a SINGLE piece of noise in throughput in 2 days of runtime. The power supply has stayed completely stable too, as tracked by my code.

Before I reconfigure my board or add an insulation protocol to the build process, I would like to know if this community who has much more experience on this front thinks that the two boards were shorting each other (perhaps that is a common problem?), or have I just been lucky that the ghost has not appeared for this admittedly small sample size? I come from a world of large-scale engineering projects and this is my first circuit board design (self-taught) so I know I have a lot to learn about design and implementation.
If the community thinks that the problem is actually occurring between the two boards when joined together, is the best solution to A) remove traces from underneath the BLE module or B) add insulation (if so what is the best insulation solution for a professional product)? I searched high and low on Google for answers to this, but to no avail. Not much I can find about design considerations when SMT'ing boards together.


texts:
I am running a PIC18F with an HS oscillator of 40 MHz. The hardware is not the problem and all the connections are properly done. The microcontroller is connected to the MCP2510 (with a parallel cut crystal of 20 MHz) via SPI, so I can interact with the CAN bus line through the MCP2551. I have done the configuration to run at 1 Mbit/s, but it is not working because it is running at 500 kbit/s. The CAN bus configuration is correctly done, but it is not running as fast via SPI as I want.

Configuration:

SJW=1
BRP=1
PSHEG1=7
PSHEG2=5
PROPSEG=7

The initialization of the SPICAN bus is done as the MikroElektronika CANSPI library.

I have been working on this a lot of time, and I think that the SPI initialization is the problem. As far as I know a 20 MHz crystal is enough to run the MCP2510 at 1 Mbit/s. Where is the problem? Is the SPI module running slower than I want?

I do not know why, but when I change the speed it always divide it by two.


texts: Impedance matching network and power transfer to the load

texts:
The picture below is a circuit consisted of an RF generator, an impedance matching box, and RF plasma reactor.

The RF generator with an output source impedance RS (= 50 ohm) is connected to an input port of the impedance matching box via the cable of a characteristic impedance of Z0 = RS. The matching box consists with CT, CL, and L and an output port of the box is connected to the plasma reactor via the another cable. So, basically, RF power from the generator transfers to the plasma reactor through the 1st cable, matching box, and the 2nd cable.

ZL is the input impedance to the box and it is the equivalent impedance of the plasma reactor and cable. When CT and CL are adjusted so the impedance matching is done, The equivalent impedance from the input of the box to the reactor (the circuit enclosed by the large dashed box) becomes ZO = RS = 50 ohms. This is a 1st interpretation of the impedance matching. I think there is a 2nd interpretation of the impedance matching that the equivalent impedance from the output of the box to the RF generator becomes the complex conjugate of ZL. This impedance is the impedance seen by the ZL when it looks back toward the RF generator. I'm wondering whether or not it is right.

I build a 2nd question by assuming that the 2nd interpretation of the impedance matching is right. In the impedance matching, the maximum power transfers to the circuit of the big dashed box, according to the 1st interpretation. The 2nd interpretation ensures that the maximum power transfers to ZL. My question is about what exactly happens in ZL. Once the power transfers the ZL, the power propagates from the one end of the cable to ZP. However, it is general that the ZP is not equal to Z0, so some power is reflected from ZP and propagates back. Since Z0 is generally also not equal to the impedance seen by ZL looking toward the generator, some power also reflects at the interface between the cable and the matching box output and the rest power transmits back to the matching box. So... there is a power reflection toward the generator even if the impedance matching is done?

Please help me to clarify this confusion.


texts: Looking for design info for a shaded pole for large contactor. Everything I find is for motors

texts: I have a large contactor with a shaded pole to prevent buzzing. The actual coil on one side is badly distorted and the other one is missing. I made two new ones as close as I could to the one I had, but they get over 500 deg in a few minutes. I don't know if the one I have is correct. The work well, no buzzing, but that is way too hot. Any practical design information would be appreciated.


texts: Is it feasible to remove non-functional via pads on outer layers

texts:
During PCB design & manufacture it is common to remove the via annular rings on internal layers where the via is not connected to anything, so called non-functional pad removal.

Would it be feasible to remove a non-functional pad on an outer layer? Would this introduce any manufacturing or reliability problems?

As a real-world example, I have a 4-layer PCB design with two outer signal layers, and two inner power layers. A BGA chip on the top layer connects to a power layer through a via, and this via takes unnecessary space on the bottom signal layer. Could this pad be removed to reclaim space for better clearance or routing density on the bottom layer?


texts: Reverse engineer a chip or go with a new one and start from scratch?

texts:
I'm working on an existing toy product and the chip has been discontinued. We still want to produce more of this product. You press a combination of buttons and it talks to you.

What would be a more cost effective approach?

Reverse engineer a chip (a possiblity based on this post: Is it possible to reverse engineer a chip design? ) and retrieve the program off of it (is this possible?). Make a new chip based on what we find.
Start from scratch and see if there are any chips that are compatible (pin assignments, features, package or die) with our existing chip. This way we can still keep the existing PCB design).
Start from scratch and use a totally different chip, which would mean PCB redesign, chip programming, etc.

Can anyone give me an order of magnitude comparison between these options?

More Details
We're talking about:

thousands maybe tens of thousands units a year
25 x 10 second audio tracks (mono)


texts: Unsure about designing an ultra wide band antenna

texts:
So, a bit of background, I have designed and measured some antennas in college so I have a decent theoretical grasp of the subject, but they were optimized for a narrow band usage and certain frequency.
I am now doing my own home project which would include an internal antenna that is supposed to be ultra wide band (from 30 MHz to 3 GHz) done on a PCB. Online resources are scarce and I do not know how to get started so that it haves any semblance of an actual antenna.
What I am actually looking for is any tips and tricks for a person who already has some understanding of a more "typical" antenna designs, I am comfortable with sacraficing efficiency for more bandwidth. If you could recommend me any literature witch discusses UWB internal antenna design, it would be much appreciated.


texts: Why use RMS values instead of "mean of absolute"

texts:
Why do we use rms values? I can't get my head around why these values are used. I am doing an intro course to elec eng and we get given some values (normally voltages) in rms and others not, and we are expected to calculate other values but I don't know when to calculate rms or when to calculate something else.

I realise that the root-mean-square is different from the mean-root-square or mean of absolute but it seems logical to me to use the mean-root-square not the rms. Why do we want to use the rms? And when do we want to calculate rms instead of another "interpretation" of the value?

I have seen a similar question to this that addresses only power calculations where voltage is squared but we seem to use rms even when we don't square anything and we aren't interested in calculating power...


texts:
In this question the solution manual takes Eb as 250v and solve it to get the torque. How's that possible ?  How can one takes the supply voltage as Eb? If there's something i don't or i didn't get please enlighten me.
The given solution :
Pd = Te*Wr

Eb=Z * P * Phi * N/(60 * 20)--- substituting values we get

N =543.47

Pd =Te*Wr = > 250 * 50 = Te * 2π * 543.47/60

Te=( 2π*N)/60 = 219.6Nm.


texts: Problems in reading a sine wave from an ADS1115

texts:
Hello I am using an ADS1115 to read a current on a SCT-013-030 based on an example setup by the manufacturer.

I have followed the setup where i have to use differential mode, and connected to the end of the transducer to A0 and A1.

What I am expecting is a graph that is a sine wave ( or relatively close to looking one), basing from the analogy that since the SCT-13-030 is a current transducer the voltage reading i should get from it should relatively look like a since wave, since the current of Mains line is a sine wave too.

Here is my code, I am using Python in MU on a Raspberry Pi 4

import board
import busio
i2c = busio.I2C(board.SCL, board.SDA)

import adafruit_ads1x15.ads1115 as ADS
from adafruit_ads1x15.analog_in import AnalogIn

ads = ADS.ADS1115(i2c,data_rate=475,mode=256)

chan = AnalogIn(ads, ADS.P0, ADS.P1)

import time
arrays = []
arrays2 = []

t_end = time.time() + 1

while time.time()<t_end:
    arrays.append(chan.value)
    arrays2.append(chan.voltage)

for x in arrays:
    print((arrays2[x]*1000,0))

and here is my output graph

I could not tell if this is the actual reading off a current from the transducer ( unfortunately i have no access to an oscilloscope ) or noise or even my programming.

The load i am using is a soldering iron.

I have tried running the program with no load and i am getting a reading of 0volts with some noise spikes here and there that are less than 0.1 which is acceptable, which led me to believe that those value are actual readings.


texts:
Can anyone identify the series of connector used for the AC input of this TDK MSA818 PSU from the late '80s?

The pin spacing is ~7.3mm (3.65mm if you count the missing pins) which doesn't match any JST series that I know of.   The pin size is ~1.1mm.

I'll be replacing it with a Meanwell RPT-60C, which uses a JST VH connector with 3.96mm spacing.


texts: How do I correctly position two connectors that must be spaced precisely while soldering?

texts:
I am having someone else assemble some very small boards I designed. There are two board-to-board Molex slimstack connectors that must be spaced precisely (3 mm center-to-center), in order to mate with another commercially available board with the corresponding pair of connectors. The assembler has requested a "mating gauge" to hold the two connectors in place while soldering, to be removed after.

This seems logical, but I can't find any reference to a soldering "gauge" through google.  Anyone know what this is or how to make it?


texts: Low frequency response of a BJT amplifier.How is the cutoff frequency equal to \$ \frac{1}{2\pi (R_S+R_{in})C_{in}}\$ in fig 2

texts:
In a low frequency region of the single stage BJT amplifier, it is the
  RC combinations formed by the capacitors \$ C_{in},C_E,C_{out}
\$ -Electronic Devices and Circuit Theory-Boylestad

Considering the equivalent  circuit formed as shown in fig.1

The output voltage and input voltage are related by:

$$\Bbb V_{out}=\frac{\Bbb R}{\Bbb R-j\Bbb X_C}\Bbb V_{in}$$
The magnitude is given by
$$V_{out}=\frac{R}{\left[ R^2+X^2_C \right]^{1/2}}V_{in}$$
$$\text{When } X_C=R$$
$$V_{out}=0.707V_{in}$$
The frequency at which this occur, is given by the equation,
$$R=X_C=\frac{1}{2\pi f_LC}$$
or, 3dB cutoff frequency
$$f_L=\frac{1}{2\pi RC}$$

In case the equivalent circuit formed by the BJT circuit is something like fig 2, which is the case when we are considering the input portion of the BJT circuit, the analysis is something like this:

$$\Bbb V_{in}=\frac{\Bbb R_{in}}{\Bbb R_{in}+\Bbb R_S-j\Bbb X_C}\Bbb V_{in}$$
The magnitude is given by
$$V_{in}=\frac{R_{in}}{\left[ (R_{in}+R_S)^2+X^2_C \right]^{1/2}}V_{in}$$
$$\text{When } X_C=R_S+R_{in}$$
$$=>\frac{1}{2\pi f C_{in}}=R_{in}+R_S$$
$$=>f=\frac{1}{2\pi(R_{in}+R_S)C_{in}}$$

But for \$  X_C=R_S+R_{in} \$
$$V_{in}=0.707 \frac{R_{in}}{(R_S+R_{in})}V_{S}$$

Which is not
$$V_{in}=0.707V_S$$

How is then the cutoff frequency equal to \$ \frac{1}{2\pi (R_S+R_{in})C_{in}}\$ in case of Figure 2
?

Furthur,

For

$$V_{in}=0.707V_S$$

$$\frac{R_{in}}{\left[ (R_{in}+R_S)^2+X^2_C \right]^{1/2}}V_{in}=\frac{1}{2^{1/2}}$$
$$=>\frac{R_{in}}{(R_{in}+R_S)^2+X_C^2}=\frac{1}{2}$$
$$=>2R_{in}^2=(R_{in}+R_S)^2+X_C^2$$
$$=>X_C^2=(R_{in}-R_S)^2$$
$$=>X_c=R_{in}-R_S$$


texts: Assembling helical antenna in production

texts:
How is small PCB mounted helical antennas (100 MHz - 1 GHz) assembled in PCB production? See picture below.

I have thought about mounting it both horizontally and vertically, but I can not figure out a process that does not require and abundant load of work done by hand. I plan on producing the PCBs in the thousands. How are these usually mounted and assembled in a factory? Why does almost all antennas include the 90 degree bend at the end? Is it supposed to be mounted in a hole or surface mounted on a pad? How are the antennas kept in place in the assembly and hand/selective soldering process? Is there any special considerations when designing a cutout in the PCB? The questions are many, the answers are few.


texts: Complex Power: \$S = V \cdot I^*\$ OR \$S = \frac{V \cdot I^*}{2}\$. Which formula is correct?

texts:
Different examples and videos have shown that:
$$P_{complex} = V \cdot I^*$$

However, my textbook shows:
$$S = \frac{V \cdot I^*}{2}$$

My professor has even using \$S =  V \cdot I^*\$ himself during an example problem, yet other problems were solved using the other formula. Which formula is correct or, if both are correct, what circumstances do you use either formula?


texts: Canbus over canberry with raspberry pi two messages together at the same time

texts: Im using a canberry with raspberry pi. Is there any way possible to send two messages at the same time with same id and be received by the other raspberry without any particular chance of getting a middle man attack ? I mean if someone is using the same id would it possible to prevent this in your opinion ? I made a research and I cannot find anything particular to this.


texts:
In CDI, the magneto-flywheel assembly along with pickup coil generates ignition timing signals which is one negative and one positive pulse separated by some angular distance used to decide the ignition time for spark. I wanted to know these:

which pulse should be used to fire the spark?
Does these pulses occur at like TDC and some x degrees befre TDC?
I heard of 3 or more pulse output per cycle, are these pulses too occur like at TDC and some angle before TDC?
Does BDC also generate some pulse in this pulser coil?
What is the significance of generating two pulse per cycle one at TDC and another some degree before TDC?

Also, please tell me if I have any misconception about CDI engine.

Thanks for answers

Ashutosh


texts: What causes a three terminal short circuit failure in IGBT

texts:
A pair of IGBTs that I was using in a high frequency application failed with 3 terminal short. The devices are rated 650V that's well higher than the operated voltage of 200 V. Snubbers were working effective in the circuit. So, the failure could not have happened due to voltage of high dv/dt, I suppose.
I specifically want to know if IGBT Gate insulation can breakdown and form a short circuit between gate and channel during channel breakdown due to high temperature from switching losses.


texts: PIC16 10hz timer with timer1 and 1Mhz clock

texts:
I need to increment a stopwatch at 10hz using timer1 on a PIC16F628. The external clock is 1Mhz, supplied by a packaged oscillator (EPSON sg8002db). With no prescaler, the value to set the timer to (I think) should be:

clock ticks in 1 second: 1000000

timer ticks in 1 second: 250000 (clock/4)

timer ticks in 1/10th of a second: 25000 (timer ticks/10)

So: 65536 - 25000 = 40536

but I need to consider the latency from timer overflow to when the clock value is reset - this is the number of cycles it takes from the overflow occurring to when I set the timer value.

The IRQ code is:

    irq             movwf   w_temp          ; save state
                    swapf   STATUS, w
                    clrf    STATUS
                    movwf   status_temp
                    movf    PCLATH, w
                    movwf   pclath_temp
                    clrf    PCLATH

                    btfss   PIR1,TMR1IF     ; timer1 IRQ?
                    goto    notimer1
                    bcf     PIR1,TMR1IF     ; yes, clear it

                    movLw   T1SPEED >> 8    ; reset timer1
                    movwf   TMR1H
                    movLw   T1SPEED & 0xff
                    movwf   TMR1L           ; timer1 is off and running again

                    call    timer           ; increment clock

    notimer1        btfss   INTCON, T0IF    ; timer0 IRQ?
                    goto    notimer0
                    bcf     INTCON, T0IF    ; yes, clear it

                    call    led_set         ; update display

                    btfss   PORTA,6         ; button pressed?
                    goto    nobut
                    clrf    digit0          ; yes, reset clock
                    clrf    digit1
                    clrf    digit2
                    clrf    digit3
    nobut
    notimer0        movf    pclath_temp, w  ; restore state
                    movwf   PCLATH
                    swapf   status_temp, w
                    movwf   STATUS
                    swapf   w_temp, f
                    swapf   w_temp, w
                    retfie

Which looks to me like somewhere in the region of about 14 cycles, so LATENCY = 14

65536 - (25000 - LATENCY) = 40550

but this gives a clock which is far too slow, losing multiple seconds per minute. If I change the LATENCY value to ~200 (eg set timer1 to 40736), it's close - within 1 second per minute, but still not accurate. In fact, with LATENCY = 199, it's too fast, and with LATENCY = 200, it's slow.

I can't see where these extra cycles are being spent - it sets the clock value first thing in the IRQ routine. I can't find anything in the datasheet about timer1 being stopped during an interrupt routine, but is it? If so, that would be a bummer, because the routine takes a variable number of cycles depending on which digits overflow.

Is it necessary to pick 2 different reload values and alternate between them in order to hit exactly 10hz?


texts:
I have a circuit here which was designed by others. It takes a 32.768 kHz IR input and outputs a logic low when the input is present. I see 3 distinct stages... everything up to U1A, everything between U1A and Q3 and everything to the right of Q3. I follow the left and the right... but not the center which is where all the magic happens.

The circuit actually works. I've wired it up and can verify that this does indeed work.

Can anyone explain the piece in the middle? It makes no sense to me. How is this circuit functioning? Why do they make use of all the gates? Why do they have a resistor in series with Vcc on U1? What purpose does R26 serve?


texts:
I am looking at BD9E102FJ buck converter, which has maximum current output of 1A.
Reading the datasheet I found this calculation:

It shows inductor ripple of 752mA with given values.

I need to convert 24V to 1V, so my ripple calculation yielded me a 247mA ripple.
I would be using this buck converter to drive 6 filaments of bulbs, which require 50mA each @ 1V, so a total load of 300mA.

My questions are: How can there be so much ripple? Is it something that Cout takes care of? Would this converter give stable 1V out, or is it not a good converter at all for this task?

EDIT: Added layout and explained application more.

So this is my schematic for this buck:

The filament voltage was rated 0.85-1.35 V and these feedback values put it in the middle.


texts:
Was looking into capacitor placement in dual ideal op-amp circuits and came across this circuit (R1=R2=R3=1kOhm, R4=10kOhm, C1=1uF):

I attempted to determine the voltage gain (transfer function) of this circuit G=(vo/vi), to which I get the following expression:
$$\frac{v_o}{v_i}=\frac{R_2}{R_{eq}}\frac{R_4}{R_3}=\frac{R_2R_4}{R_3R_1}(1+sC_1R_1)$$
where Req=(R1||(1/sC1)) and s=jw=frequency variable.
I decided to plot a Bode plot for this transfer function and obtained an unstable result at high frequencies, as expected since G approaches infinity as s approaches infinity. However, when I simulate this circuit (I used CircuitLab) the Bode plot I obtain is similar in shape to that of a band-pass filter.
This has me thinking that my derivation of the transfer function G is incorrect, and that it should match the transfer function associated with a 1st order band-pass filter. Would someone be able to confirm my suspicion?


texts:
I'm looking for a source for the mating part to the proprietary USB connector on the Kinect, which includes standard USB signalling and power, and also the special 12V supply rail. The cable version of it comes on the dongle in the Kinect box, but it would be awesome to be able to have (or somehow fake) the PCB-mount one which is in the new 360.

Any ideas?

Just to give an example of where I'm at, I note that of the nine contacts inside the Kinect connector, you actually only need to contact the ones on the side with the angled corner:

Would it be possible to simply put five mating stripes on a PCB, and then put a shim on the other side of it to make it the correct thickness? (It's actually extremely close to just being 2x PCB thickness.) Would just traces in contact be enough, or would it need to be an actual springy component? If so, is there one that the community could recommend? Bonus points for something that can be populated by machine.

Here's an example of someone who made one out of two butchered USB plugs. Anyone know how to buy pieces of USB connectors?


texts:
I'm trying to get a button to work on my Beaglebone. I bought MAKE Volume 32 and tried to follow the guide in there.

But when I read the GPIO pin, do I always get 1.
I also tried to disconnect everything and is still got 1 from that pin.

I tried to read the value using the file systen as following

echo 70 > /sys/class/gpio/export

cd /sys/class/gpio/gpio70

echo in > direction

cat value

Here is my setup.

The resistor is a 10k resistor and the button is a arcade push button from Adafruit.


texts: Why does diode keep conducting even after voltage across it is negative

texts:
consider single phase two pulse semiconverter asymmetric configuration.

simulate this circuit – Schematic created using CircuitLab
Note the high value of inductance L1.
Let a be trigger angle of SCR, which is greater than t = arcsin(E/Vs). Now the SCR will work from a to pi-t and maybe beyond if current does not fall below holding current. But would not the diode D2 turn off after pi-t because voltage falls below zero?
Why does using a high value of inductance allows current to flow in D2 beyond pi-t and upto pi+a ? Does the emf E play no role in switching off the diode?
What actually happens after pi-t to pi+a? I assume that D3 cannot start conducting before pi+t and SCR4 cannot start conducting before pi+a. So where does the inductor current go?


texts: How do calculate / determine the reference voltage for the error amplifier of my analog PWM generator for a 0-100% duty cycle

texts:
For a school project I am building an analog PWM generator with 0.1 to full-scale linearity and a duty cycle 0-100%. Powersupply is 5 Volt and 100% is equal to 5V at the output. The frequency 1 Khz.

My circuit is done for like 80%. The problem I have is with the reference voltage of my error amplifier. My research so far has shown that this gives you the ability to have the 0-100% duty cycle.

When I apply a reference of 2.5 Volt, I see that my dutycycle is 50%. When I change Vin to change the duty cycle , it changes with 0.5V to 0% or 100% from reference voltage.

So,
2V = 0%

2,5V = 50%

3V = 100%

Sidenote:

I used the slau508 design and theory, but my design differs slighty because mine is not going to be used for audio, hence why I need to adjust the reference voltage according to my teacher.

How can I fix this so that I can change the dutycycle from 0 to 100%?

I need to have a reference voltage for my error amplifier so that I can have a duty cycle from 0-100% with a voltage change of Vin from 0-5V.

With the reference of 2,5V that I have right now I can only go from 0 to 100 procent with an increase or decrease of 0,5V. This should be 5V in order to change between 0 and 100% dutycycle.

My question is:

How can I calculate or determine what I have to do with the reference voltage in order to have the 0-100% duty cycle with a voltage change of Vin from 0-5V?


texts: So, for a small home-made engineering project I have cannibalized a 14.4 V DC 20 A motor from a Bosch battery powered screwdriver/powerdrill to spin a flywheel. I'm still using the trigger (drillswitch) from the powerdrill to control the speed of the motor but I want to switch this control for a variable resistor w/ potentiometer for preciser control. In other words, I am trying to make a speed control. How do I do this? What do I need? I will still be using the 15 V 1.5 Ah battery.


texts:
INTRO: (PS, if you're not interested, skip to the last paragraph)
I'm building a battery pack for my university electric racecar team. We plan to use 18650 cells, the Samsung 30Q which are only rated for 15A continuous. However, Mooch over at e-cigarette-forum tested them and shows that they are capable of 20A continuous and 25A peaks -
https://www.e-cigarette-forum.com/t...t-results-a-great-20a-3000mah-battery.727190/
However, in his testing, he pushes them to 50A pulses for 5 seconds and they still work fine. Due to weight and size constraints, we're forced to use the batteries in 8 parallel circuits. According to Samsung's datasheet, that's only 120A continuous, but going by Mooch that's 160A continuous with a 200A peak. We might, however, draw up to 270-300A in very short bursts of less than 5 seconds, that's a burst from the battery of about 37A.
Our problem is that we are required by the rules to fuse the batteries at the rated max current of the cell which isn't mentioned in the datasheet, and results posted on a forum don't count as scientific evidence of max possible current. Moreover, we have a custom cooling solution which should help increase our peak currents even higher than the tests mentioned above.
Our only option then is to test the batteries ourselves and show sufficient proof of the max current, which brings me to the problem I'm having. A single cell, going by the aforementioned tests should be able to output 50A+ and thus a pack of 8 of them can easily exceed 400A given proper cooling.
Why do we need to test the whole pack of 8 you ask? If we blow the fuse on one cell, say if its defective, or even just badly welded on, the remaining 7 cells will have to supply more current than before. We need to ensure that it won't cause a chain-reaction of fusing all the cells and break the circuit.

To test the batteries, we need some sort of current limiter and load. All the circuits I found here and elsewhere are rated for around 50-100A. How would I go about building a battery testing rig at that can limit up to currents of 350A? Could I do a multiple parallel BJTs in a current mirror circuit configuration? Are there any caveats to that?
Also, what safety precautions do I need to take considering I'm pushing these cells to their limits and to failure?
I appreciate all the help and suggestions I can get

EDIT:
I realized there were some additional calculations I missed. The lowest allowable battery voltage(not cell EMF) is 2.5V. At 40A, that's an external load of \$62.5\,m\Omega\$. To reduce power dissipation of the current limiting circuit, I can add a power resistor of that resistance in series, limiting the power dissipation of the current limiter to \$20*20*62.5*10^{-3}= 25\,W\$ (Max power dissipation when loads are matched).

When testing 8 cells in parallel the external impedance can drop to
 \$62.5/8=~7.8\,m\Omega\$ and power dissipation through the limiter would be about 800W


texts:
I am looking to build a float sensor for a tank and automating the motor based on sensor input. I am looking to execute this without using a microcontroller.

Below is my intended sensor setup in the tank. This is a magnetic float sensor which acts like a simple switch which closes when the water reaches its level in the tank.

The circuit uses two float sensors. One should be fixed at the top of tank (top float sensor or TFS) to detect when the tank is full to signal the motor OFF and another sensor (bottom float sensor or BFS) at the bottom of tank to signal the motor ON when the water level goes to the lowest point of tank.

There are 4 scenarios this circuit needs to meet:

When water level is full activating TFS, the BFS will be in activated state as well. In this case motor should be turned OFF.
Water consumed it drops down but still over the BFS, in this case the motor should be still in  OFF state
Water gets consumed further and it drops down below  BFS, in this case motor should be turned ON to fill the tank
Water fills up the tank and it crosses the BFS level but still below TFS, in this case the motor should continue to run and fill the water until it reaches the TFS.

From the above scenarios I have plotted a small logic table that needs to be achieved.

I have designed a circuit using D Flip Flop and 3 input NOR gate. This circuit meets the need for first 3 scenarios or meets the first three logic in the above table however I cannot figure how to meet the 4 scenario. I am stuck with this for a day now, any help or tip is highly appreciated.


texts: Is my instrumentation amplifier's voltage offset causing problems?

texts:
I am using an MCP6N11-100 to amplify the signal out of a 2 mV/V load cell with a excitation voltage of 10 V, so the maximum output (differential) would be 20 mV. The load cell is rated for 4000 kg.

I am using the instrumentation amplifier in the following configuration. Note that at the inputs I have the outputs of the load cell connected directly. Rf = 9.9 kΩ and Rg = 55 Ω giving a gain of ~181 (both resistor values are measured). VREF is grounded.

My problem is that the gain doesn't seem to be 181 until there is sufficient difference between the inputs of the instrumentation amplifier. Suppose the difference is just 0.5 mV. The op-amp outputs 200 mV giving a gain of almost 200! However, as the difference is increased to 2 mV the output now is 366 mV to 368 mV - matching the gain much more accurately (183 vs 200). Why is this discrepancy present at low levels of input? My guess is that it's the offset voltage. The datasheet suggests that the MCP6N11-100 has a maximum Vos of 0.35 mV. Could this be the cause?


texts: Bidirectional assignment in Systemverilog

texts:
I need to create mux block that works with inout pins.
My module has n inputs and n outputs, I want to be able to switch
between different outputs.

The problem that I am currently having is that I need to do that with
inout pins. So if my output pin is pulled down, the input pin of the
mux shall see that. This doesn't work with a common assign statement since
it will only write in one direction. I have tried an alias statement, which
works like a bidirectional assign, but I can not combine this with an if statement for the mux.

What I want to do:

alias net_out = (config) ? net1 : net2;

I have created an example on edaplayground


texts: How to determine MRF24WG0MA wifi bottleneck?

texts:
I have a PIC32 running a MRF24WG0MA (which is a b/g wifi transceiver which supports up to 11MBaud on b and 54Mbaud on g).

I have measured the sustained transmission thruput over several minutes at approximately 800 KBaud.  I was hoping to get several MBaud.

I get MBaud speed from a laptop on the wifi network so I don't think it is an infrastructure problem.
I think it is either the PIC32 or the MRF24 chipset.

What is the best way to determine where the bottleneck is?

Currently my approach is to first analyze the packet timing with WireShark, then dive into the TCP/IP Stack provided my Microchip.


texts:
In power systems, I understand why S=VI*. However, I am having a hard time understanding why I=S*/V*.
Can someone explain, or better yet prove, that I=S*/V*?
You don't have to prove it under power system conditions, I just want to know the property that falls under this conjugate proof.
Thanks,


texts: Programmable current laser drive circuit

texts:
I'm trying to design a circuit to programmably control the laser drive current from 0-200mA. The current needs to stable (<50uA variation)  but with a settling time of <1us (faster if possible). The circuit has a current limiting resistor and an on/off switch. There is also a monitor ADC to measure the current.

I'm concerned about:

Oscillation between OA1 and M1
DAC output variation due to supply ect.

Should a cap and resistor be placed in the feedback loop or on the OA1 output to limit possible oscillations?

What are the calculation steps to work out the required slew rate / bandwidth of the op-amp and filter value?

Is there a way to improve the DAC output? This circuit uses a ratiometric DAC, is this a good option?

simulate this circuit – Schematic created using CircuitLab

EDIT: The application requires the lasers be completely off at all times when LASER_ON is low.


texts: How do I create a visual and/or auditory indication that an inverter has switched off and the mains are back on?

texts:
EDIT

I came to know that o/p of inverter is AC. I apologize if I sounded silly previously. To be more specific,

How do I create

a visual indication
an audio indication

in my living room such that a bulb switches on when the inverter works and switches off when the mains work and also if possible hear a beep or a string of beeps in my living room to know when the inverter has switched off and the mains are back on?

My first question in electronics SE.

I have an inverter at home, India. It always beeps 4 times when the power goes out and it switches on. But, when the main line comes back on, there is no beep or indication except the small LED on it. It'd be really useful/helpful if something can be done to let a person (my parents and grandparents at home) know that the main is back on and the power is running on the mains and not the inverter. It is kind of painful for them to go check out whether or not the power has come back every single time, because of its location and because of the frequency of power cuts here. The inverter is a basic one (supports just one fan and light), so they need to check so that they can run essential items like mixer, washing machine, etc. when the power comes back.

Are there any ideas or suggestions as to how I can proceed or what I can do? I thought of two ideas, one is a simple beep (or multiple beeps) and the other is a bulb (a small one) situated at a comfortable place in the living room which can switch on when the power is on the inverter and switch off when it is running on the mains. I don't exactly know how to proceed or what to do here.

NOTE: I don't want to touch the inverter for any purpose here because if I screw up then it'd be an additional expense to call someone to fix it.


texts:
I've removed a capacitor, but like the n00b I am, have forgotten which way round it went.

From this picture can you deduce the polarity?  It was removed from the board in the circle with the two holes.

There is a plus + sign there, but that might be related to a much smaller blob to the side of it, and the circle is marked slightly thicker black on one side.

Any ideas?

EDIT

Added pic of other capacitor.  Yes - it does follow the pattern.  Thick black signifies neg.

I will proceed.... wish me luck!

THANK YOU GUYS!

It worked... my first cap. replacement...

Old dreambox PSU back from the dead.


texts: PSpice VSIN frequency - how to set it in rad/s?

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I know, that if I want to set FREQ, I need to set it in Hz, not in rad/s. I know, that

1 Hz = 2*pi rad/s,

but how to do this in PSpice? What should I enter exactly?

and btw. if I want to set VOFF (voltage offset), I need to pass it in volts, not an angle. How to convert it, so I could pass angle as an offet?


texts: Will coiling a mains power electrical cord cause interference?

texts:
I am a maker working on a lamp design in which a decorative power cord is wound through the structure, creating a coil down the lamp's main structure. The coils are about 3cm apart and the same in diameter, and the power standard is 220V.

I'm pretty certain that this isn't in any way dangerous, however will coiling the cord in this way cause any interference with other electronic devices? Are there any other concerns?


texts: why boost PFC topology is the most used?

texts: While searching about power factor correction topologies, the topology I came across almost all the time was the Boost PFC topology, and I'd like to know why? why is it the most widely used one, in comparaison to say, buck PFC or flyback PFC.


texts:
I have two questions regarding paging in EEPROM here:

What is paging in EEPROM?
In what situations is it normally used?

If you can provide an example with the AT24CXX that would be much appreciated.