texts: Oscilloscopes and Packed Two-Layer PCB boards? (“Operating Table” PCBs)

texts:
I have recently completed a very complicated 2-layer circuit board. Every square mm has a component in it, two of the sides undergo edge plating, and one is riddled with right-angled connectors.

I would like to use my oscilloscope and logic analyzer to help me debug this circuit, but that will require having somewhere to plug the probes, as the analyzer has two rows of 8 female plug sockets separated by 2.54mm.

Credit: Rigol Technologies

Notice how the evaluation board that comes with the kit has been set up so that the probe can plug straight onto the pin headers.

Many other development boards I see follow this convention of laying out the design with pin headers connected to relevant nets as well:

Credit: ST Microelectronics

This setup with pin headers seems user-friendly and I would like to design an “operating table” pcb board which contains the two-layer board that I plan on producing at the center. On the free edge (non-plated and without connectors) another extrusion will jut out that contains rows of pin headers. To connect the headers to the nets, I will add two more layers in the center of the “operating table” pcb that will not be present in the final design. On those layers, I will snag nets from vias passing trough the board and route them to the headers. (Almost) all of my nets pass through the board through vias.

What considerations, aside from the effect of separating the two outer layers a bit (which can be compensated for by changing the board thickness during fabrication), should be taken in laying out such a design? All of my signals are under 20MHz. Should I be concerned about coupling on the inner layers?


texts: STM32F411 - I2C failure during heavy polling load

texts:
I have a STM32F411 communicating to 2 peripherals (an IMU - MPU6050 from Invensense, and a LED Driver - CAT3626 from ON Semi) over its 2 I2C buses (one peripheral per bus).

I'm running into a strange issue - if I try accessing the registers on the two devices too quickly, the peripherals eventually stop responding. There is no hard fault - to the microcontroller its as if the device is not connected anymore.

I originally thought it was an issue with the peripheral, however, on deeper investigation it seems the peripherals are not an issue, since if I reinitialize the I2C bus on the STM32F411, I can communicate out to the peripherals again.

Adding a timeout to ensure I only poll each device's register's every 100ms has helped reduce the frequency of the issue, but it still shows up every now and then. I'm hesitant to increase the delay as 100ms already seems like a long time, and any longer and I risk missing critical samples from the IMU.

I'm looking at other workarounds (a timer interrupt to sample the IMU so we have the longest possible delays), but there is not guarantee they will work. I'd rather spend more time understanding the root cause first, but I'm out of ideas as to where to look.

Any thoughts?


texts: How is the power calculated for Si(t) in the picture?

texts: The formula I've seen is to multiply the signal by its complex conjugate, then integrate across the time period interval, and then divide by the period. But when I do that I don't get A^2/2


texts: Help understanding the voltage waveforms across the components of a series RL circuit

texts:
The waveforms shown below are voltages taken across a 10 Ohm Resistor (pink) and an 1mH inductor (blue) in series with one another. The circuit is excited by a 1 kHz, 1 volt peak-to-peak sine wave. What is happening that causes the waveforms to flatten when the resistor waveform is at it's peaks? Someone suggested it had something to do with the ESR of the inductor. Is this correct? If so, how does it have this effect? If not, what is actually going on?

Here is a SPICE rendering of the schematic for good measure. But the waveforms shown above are not simulated, they are measured from a physical circuit.


texts:
I've built an audio adapter for car stereo system. It contains microcontroller, a connector to stereo system (a few data pins and line-level audio output), Bluetooth audio module (RN52) and power connector.

I've successfully tested it with a separate, floating power supply, and audio noise falls within my expectations.

However, when I power the adapter with a power supply which is also referenced to audio amplifier/speaker system, I am hearing significant noise. This happens in car, but I also hear the same issue on my desk, if I power the PCB from PC's USB port, and speaker system is also referenced to my PC.

I kind of suspect grounding issues on my PCB. When designing it, I did not pay a lot of attention to routing GND pins of the modules/ICs used- I relied on having ground fills on both sides of the PCB.

This is a high-level overview of the PCB I made:

I recall having heard about "star ground" concept, where all the ground points should connect in a single place, power input connector.

The questions are:

1) How applicable the star grounding is if there are multiple connectors (each with a separate ground wire), which may, or may not be referencing a "common" ground somewhere further.

2) Is it possible to improve noise with a different/proper grounding on my PCB, or should I isolate either the audio output or power input?

Images of the actual PCB layout (warning, hairy stuff):

Top: http://faili.wot.lv/tmp/2014-11-02_03-12-03.jpg
Bottom: http://faili.wot.lv/tmp/2014-11-02_03-12-13.jpg
Both: http://faili.wot.lv/tmp/2014-11-02_03-12-21.jpg


texts:
I'm building a pet-project that involves a 'dumb' chinese USB PD IC (IP2721) and I'm trying to figure out if there is an analog solution for this problem:
Basically I have two circuits that require different voltages. Circuit A +9V and Circuit B +5V.
If voltage is 9V current flows to circuit A, but not B.
And
If voltage is 5V current flows to circuit B, but not A.


texts: What factors affect the threshold voltage in MOSFETs?

texts:
Does orientation of the MOSFET devices on a chip affect the threshold voltage similarity (matching?)
What are the factors affected by different orientation.


texts: How do I measure an 'industry standardised' noise given Vrms ~ oscilloscope settings?

texts:
I have an example of a noise source, but the specific device is unimportant to the fundamental aspect of this question. I'm trying to measure it's level with an industry standardised method so that I can share and compare it in a meaningful way.
I can't imagine how to arrive at a singular figure such as Vrms.  I used a digital 1 GSa/s oscilloscope with the 20 MHz bandwidth limiter set on. I got:-
   mVrms   Sa/S    Depth
   -----   ----    -----
    155     25 M      6 k
    236    250 k      6 k
    382     25 M    600 k
    457    250 k    600 k

By virtue of the sampling theorem, I sampled the noise at 12.5 MHz and 125 kHz (trying to stay well away from the 20 MHz limiter).   I also varied the memory depth between 6,000 and 600,000 samples. Vrms seems very much related to both settings. I measured a 'range' of ~3x for Vrms (457 mV - 155 mV).
It seemed easier with the old (green screen) analogue scopes. The had infinite horizontal resolution. I seem to be able to 'select' the Vrms I want when using a digital scope. (Is this progress?) A simple RMS value seems to exclude all concepts of crucial sample depth/sample rate. And different scopes have different sample depths/rates.
Q. How do I measure an 'industry standardised' noise Vrms that I can share with other people, given that Vrms ~ digital scope settings? What scope settings?
Supplemental:
It seems that you don't. Ti's note How to measure LDO noise suggests that spectrum analysers are used instead.  I don't have a spectrum analyser.

I've seen Measuring noise with an oscilloscope, How to measure broadband noise (unanswered)  and How to calculate RMS of total noise from digital Oscilloscope (FFT)? , but they don't seem to address the point of noise readings being related to scope settings.
Hope this isn't too much stuff, but these are the relevant screen shots for exactly the same noise source:-


texts: How to prevent false trigger to PIC chip input

texts:
I am trying to use an off the shelf battery operated device in a larger project.  The device was powered from 4 AA batteries which I've replace with a +5V power source. The device uses a 16F505 PIC chip and it's operating range is 2.2V to 5.5V.
PIC Spec Sheet

I have replaced the start button with a simple relay contact closure, externally controlled. The device's Start input is tied to Vcc with an EXTERNAL 20K pull-up resistor. The Start button shorts the pin to ground to start the action. In testing, when I simply place a test probe on the power input the device also starts on its own. Also, I simply touch the pad leading to the Start with a test lead (without shorting to ground) and the unit will start.  I tried adding a 1000uF cap at the device power input that didn't seem to reduce the "spontaneous starts".  I don't think I can increase the pull-up resistor value as the spec sheet says for 5.5V typical is 21K and max is 23K. I think a filter on the power input would help but I'm unsure and also unsure how to spec one. Can someone advise on selecting one and perhaps offer additional tips or possible solutions? Thanks in advance!


texts: Why don't we have very high layer count PCBs (usually a maximum of 4-6 layers)?

texts:
It seems like there has been so much research being done on making circuits and components that are smaller and smaller, but at a certain point we are going to be designing components and boards that are literally just a few atoms wide.

Why is it that companies pour so much money into making say a 4 layer circuit board that is 10 square inches still only a flat 4 layers but maybe 8 square inches, rather than just making an 8 layer board only 5 square inches for example? (8 is still possible and it is done, but why isn't this taken up to say 100 layers or more?)

Also does this same principle apply to IC design? Are ICs usually only a few layers and spread into thin sheets, or are they typically built more vertically?

*Edit: So one thing that has become apparent to me from the comments is the fact that in circuit board design you can only really place components on the outer 2 layers. That would make inner layers unnecessary for anything other than weaving. What about in IC design, something like an intel processor? Are there still special components on the outer two layers, or is a processor more 3D than a circuit board?


texts:
I have a USB keyboard which has a somewhat faulty wire. On shaking the wire, the USB keyboard sometimes gets disconnected or sometimes gets connected. This is normal.

But I have another very strange phenomenon with my keyboard: On switching on/off the tubelight in my room, I hear the USB disconnecting and reconnecting sound clip in my computer. This only happens when my keyboard is connected to my PC.

I do not have any light sensors in any device. Or is this due to some fluctuations in the voltage that the USB kb gets disconnected for a few milliseconds?


texts: Teensy 3.0 (TeensyDuino) + L3G4200D === "574" reading? Why? How to fix?

texts:
I have an Arduino Uno, an Arduino Nano, a Teensy 3.0 and a 3-axis gyroscope (L3G4200D module from Parallax http://www.parallax.com/StoreSearchResults/tabid/768/txtSearch/gyroscope/List/0/SortField/4/ProductID/778/Default.aspx)

When I hook up the Arduino Nano or Arduino Uno to the gyroscope and use the sample code provided at the bottom of this page, it works great: http://learn.parallax.com/kickstart/27911

I get the readings I expect from the gyroscope.

When I hook up the same gyroscope to my Teensy 3.0, I get readings... but they aren't quite right. Instead of reading (x, y, z) 0, 0, 0 at rest, it will read 574, 0, 574. Sometimes 574, 0, 0, and sometimes 574, 574, 574.

When I move the module around, though, the numbers read closer to what I would expect from the Arduino boards.

I'm still very new to hardware. I understand some of the basics, and I know enough to make sure I have all the right wires plugged in to the right pins, etc. I'm sure there is something in the sample code that I'm using causing the problem - after all, this is arduino sample code that I'm using with a teensy...

I'm coding in the Arduino IDE w/ the TeensyDuino add-on. I have the board configured correctly in the Arduino options, of course.

Does anyone have any idea why my X and Z axis are reading 574 most of the time? What do I need to do to fix this?

[EDIT]

Per comment requests, here are images of my setup.

The Teensy setup: http://cl.ly/image/0E3R0x380d3R

The Arduino Nano setup: http://cl.ly/image/2S1J03123L16

As you can see, the setup is the same - just putting the pins in the right place for the controller I'm using. The Nano produces the correct results, while the Teensy does not.

[EDIT]

Would the Arduino being 16 bit while the Teensy being 32 bit cause problems? Do I need to adjust the math to calculate the two's complement differently? Use different variable types to store the resulting information? Or am I thinking wrong on this path?


texts:
Full disclosure: I'm fairly new to all this hardware-stuff

Prologue:
I have old bluetooth speakers that I wanted to be run from a normal 5V USB-Powerbank.
Which worked perfectly but the music was pretty quite.

So I installed a Boost Converter Link to step up the voltage to 9 Volt (Standart power supply voltage)

Here a picture:

I simply replaced the battery input with a USB input

Problem:
As soon as I connect the Powerbank it shuts itself off.
When connecting the Boost Converter to the Powerbank via a USB to TTL Converter it works just fine.
So what is the difference? I only have ground and 5V hooked up.

I think I maybe need a capacitor, but I have no clue what kind of capacitor and what other specs to pay attention to.
I went for the cheapest Boost Converter I could find straight from China. Should I maybe invest a bit more?

Thanks in advance


texts: 16 bit analog reference voltage design for stm32 chips

texts:
I am trying to make custom 2 layer PCB using stm32 microcontrollers for my flight simulator rig. My intention is to use magnetoresistive sensors in the joystick to get 14 or 16 bit signals and interface them with PC using stm32 chips. Will a linear power regulator with decoupling capacitors getting power from USB be sufficient for supplying analog reference voltage?
I am considering using the design shown in the attached video.
https://www.youtube.com/watch?v=C7-8nUU6e3E&t=6511s


texts: 1:1 and flyback transformer at low frequency and high temperature

texts:
I am designing a circuit in that I need 1:1 and fly-back transformers at low frequency (0-100kHz) and high temperature. Can anyone help me with these?

I am looking for voltage being handled around 12V, if possible at 175-200°C, with same voltage isolation.

I need fly-back transformer to buy from the market but not to design.

I found this one but not useful in my application transformer link

I found 1:1 transformer for my application at BHelectronics 1:1 transformer.

I am looking for one more transformer at same temperature which can provide +10v/-10v power supply from battery.

I need to get +/- power supply to my electronics from the battery. I am trying to find a transformer to do this job. Can anyone help me with this kind of transformer.

I can't disclose my application, i am sorry about it!.


texts: SPDT relay as SPST: why tie common to NC?

texts:
I came across a circuit that switches line-connected heating coils using relays.  The relays are SPDT, and are connected as so:

simulate this circuit – Schematic created using CircuitLab

Why connect the relay like so?  My intuition would be to just leave the NC contact open.  Is there some subtlety that I'm missing?

The only thing I could come up with is that connected these two leaves more room for thicker copper on the LINE trace.  Behold the relay's pinout:

This way one could route a beefy trace through the NC and common (left and center, respectively) instead of slimming down at the common pins to avoid the NC ones.


texts:
I have an RF IC (ADF4113) with input impedance (@500MHz), given as (85-j263)ohms.

So this could be seen as a 85 ohms resistor in series with a -j263 (1.2pF) capacitor.

The datasheet says the Input sensitivity is minimum -15dBm or about 32uW in 50 ohms load.

Ok, now for the question: So I need to feed minimum 32uW into the input, but the input impedance is complex, so do I just calculate the RMS voltage needed on the input, with 85 ohms as reference?
Or do I need to take account for the complex part (-j263)?

I know it is not possible to deliver power the the complex part (-j263), but not sure if it has some other effect.


texts: High side current monitor to measure microamps

texts:
I am trying to sense very low current (50 - 200 uA)  on the high side of a circuit, and was considering LTC6102HV for the job since it can be "floated" to 105 V.

My problem however is that my circuit is not floated to +105 V but to -105 V and the current does not flow to the ground. if I understand it right, I cannot use LTC6102HV.

Here's a picture that illustrates the problem, I am trying to measure I_sense, across R_sense.

I can probably just use a diff amp (e.g. AD629), but since I am measuring microamps, I am not sure if it is the right way to do it.

Any ideas?


texts:
I'm trying to find a circuit capable of boosting a normal alkaline battery or maybe a li-po to 5V/500mA. I want a through hole IC to try it on the breadboard.

Vin could be 2.5V (or lower) and maximum 3.7V.

Is there any DIP package capable of doing that? A diagram would be appreciated too.


texts: Purpose of 1 microfarad capacitor in IR receiver circuit

texts:
What is the purpose of the 1 microfarad capacitor in this circuit? The source webpage says:

  Output of TSOP1738 oscillates at the rate of 38KHz, which is applied to clock pulse of 4017. So we have connected a 1uF capacitor across the output of the TSOP so that this 38KHz pulse train is counted as one clock pulse to the IC 4017.

However, I could not understand what this means:

  So we have connected a 1uF capacitor across the output of the TSOP so that this 38KHz pulse train is counted as one clock pulse to the IC 4017.

The circuit does not state the voltage of the capacitor, but I bought and used a 1 microfarad 16 volts capacitor. How 1 microfarad capacitance and 16 volts rating of the capacitor affect this circuit? Is the capacitor really needed?

Source webpage (remote-controlled light switch):
https://circuitdigest.com/electronic-circuits/remote-controlled-light-switch

UPDATE:

If I understand correctly, each pulse from a TV remote control for example produces a maximum of 6 volts at the output pin of TSOP1738 and charges are stored in the capacitor. But how does the capacitor know when to release the charges it holds to IC's pin 13? Does the capacitor wait for the burst of pulses to finish before releasing the charges to the IC's pin 13?


texts: How to enable c++11 support for Atmel Studio?

texts: I am currently using Atmel Studio 7 and I need to enable c++11 support for it. I couldn't find any documentation about this topic. Moreover, I am not even sure it has c++11 support, yet.


texts: Are eDP driver boards compatible between resolutions?

texts:
I'm looking at various eDP to HDMI controller boards that are available. The ones that I've found identify a very specific resolution: 1920x1080 or 1366x768, etc.
If I buy a controller board for 1920x1080, can I hook it up to an eDP panel that is a lower resolution? Or do I need a board that specifically matches that resolution.
I do understand that some panels require a different number of pins and wires; 1-lane or 2-lane, 30 or 40 pin, etc. This question is not about the cable but the driver board and panel mating once a compatible cable has been used.


texts: How can I hook up a simple MOSFET to amplify the PWM signal from Arduino?

texts:
I have an 8-ohm 1/2 Watt speaker I'd like to hook up to the Arduino. I'm currently hooking up the gate of a FQP30N06L MOSFET to the PWM output of the Arduino. I've tied the drain to Vcc (5V) and the source to the (+) speaker terminal, with (-) speaker terminal to ground. I also have a 10Kohm resistor from the MOSFET gate to ground.

This gives a pretty good volume output, but I'm worried about two things:

Doesn't a speaker act as a short for DC current? I'm afraid this could fry the MOSFET.
This seems to run a DC current component thru the speaker, which I'd like to remove.
There is a lot of high-frequency "ringing" (bad audio quality)

I've tried other things, but the speaker just isn't loud enough. For example, putting a resistor in series with the speaker makes the sound too quiet. Also,  using a DC-blocking capacitor in series with the speaker results in no audio output.

Is there a better way to amplify the PWM signal and block the DC component?

The PWM signal ranges from 0-5V (square wave) with a frequency of ~30Khz.


texts: About Quine-McCluskey method on circuit design and don't cares

texts:
My teacher have give me a question is like this.

  Design a 2-of-5 Code to BCD 8421 Code converter. Minimize each of the output to SOP form using Q-M method and draw the circuit diagram using basic gates (i.e. AND, OR, NOT gates).

Can I treat the non 2-of-5 code output as logic 0 insteat of don't-care terms? because I dont have any idea how to do the QM method without error with 22 dont care term. =.='


texts: Is there any open source alternative to MyHDL? I have started learning but finding it very difficult.


texts:
I'm trying to build a basic circuit that can monitor a thermocouple, compare the resistance to a known source and then adjust a valve to maintain a certain temperature.
I have designed and tested the circuit to compare the thermocouple with the known voltage and have an output of between -5 and +5v.
Ideally I'd like to take that variable voltage and simply add it to the voltage currently going to the valve so the final voltage will either go down, stay the same or go up.
Is there a way I can use an op amp to monitor the final voltage and the sum it to the variable one? I've attempted to use a capacitor as a 'memory' for the final voltage, but I'm not getting anywhere.
As a side note, I'm running at 24V with a virtual ground to create +-12V.
The thermocouple and known source are both variable resistors with their outputs going through a differential amplifer to give the -5V to +5V range.
The valve takes a 0-20ma signal which I'm generating from 0-5V.


texts: How to Reset ESP8266-01 with a proximity sensor

texts:
I really would appreciate your help.
I'm trying to build an external circuit to reset my esp8266-01 when my proximity sensor is triggered. Why am i doing this ? When the ESP wake up from deep sleep (by the reset pin), a motor DC is activated and after some delay, the esp go into deeep sleep mode again.
So instead of using a button to wake up the ESP, I really need the promixity sensor to act in similar way. So while the sensor is not triggered, the reset pin logic level is HIGH (1). Then when the sensor is actived, the reset pin logic level become LOW(O).
After the context above, i need an external circuit to wake up the ESP when the sensor is triggered and keep the reset pin logic level HIGH until another trigger provided by the sensor wake up the esp again...

What this circuit above does? It turn the led off and then quickly turn it on... just a way to simulate kind of waking the esp depeding the input logic level sensor.
In other words, the external circuit must do this:
[][1
Sorry for the portuguese language describing the wave output. What matters in the picture above its just the output response that the external circuit must provide.
Someone could please help me how can i achieve it ?
Since now thanks a lot!!!!


texts: strong capacitive coupling of mains to isolated output of AC/DC converter?

texts:
I am using a RS-15-5 PSU from Meanwell for a test: datasheet here
I built the following circuit:

The left side (V1) is the mains side. The right side (V2, C3, L1, C2, R2) is the isolated DC side.
As a first test, I connected only R1 (and not C1) between earth and the isolated output. And I believed that this would pull the 0V node to Earth potential
To my surprise when checking the output voltage with an oscilloscope I got about 100V AC at 50 Hz on the 0V node. After checking with Spice, this leads me to believe that there is about 10 nF in C4 which is a parasitic capacitor.
When I added C1 to the circuit, the voltage of 0V with respect to earth was reduced to a couple of V at 50 Hz. See the scope shot taken of the 0V node, referencing earth.

Still this is a tremendous common mode voltage and spice tells me that there is mA's of 50 Hz common mode current through C1 and C4. When I short out C1 and R1 with an Amperemeter, the 0V voltage collapses as expected and I read 3 mA AC of current.
How then are isolated power supplies used without failing all EMI tests ? The output nodes will unavoidably have a large potential to all earthed conductors, e.g. the Chassis ?
Replacing R1/C1 with a short would get rid of the large common mode voltage but the output would not be isolated anymore.
Where is my problem in understanding ?
EDIT:
I checked two other wall plug AC/DC converters, a 3 prong one and a 2 prong one. Both showed similarly large AC common mode voltages with respect to Earth on their isolated DC sides. So I would exclude a fault in the Meanwell PSUs.
My conclusion at this point would be that all equipment running off isolated AC/DC converters would be floating around at large 50 Hz common mode voltages, unless its DC side is bonded via a very low resistance to Earth. Is this indeed the case ?


texts: Mixed forward voltage LEDs in series with constant current driver

texts:
I've been looking for answers for a few weeks, so now I'll actually voice my question!

My plan is to power 109 LEDs in series off of one constant current driver. The goal is to create supplemental light bars for a greenhouse. 3 bars powered from 1 driver. The plan is to maximize efficiency, reduce electrical waste, focus on the specific wavelengths for photosynthesis, and take advantage of the Emerson effect.

The driver model is Meanwell HLG-185H-C700. In order of forward voltages from low to high, there will be 11 at 1.7v, 46 at 2.2v, 25 at 2.8v, 11 at 3.5v, and 16 at 3.6v. The driver outputs 286vdc @ .7A. All the drivers are rated at .7A.

Can I simply connect all these LEDs in series?

If that isn't a workable solution, what are my best solutions?

I've considered the following, but any complications to the circuit increases costs and decreases efficiency:

Wiring each group of Vf to its own CC driver with the appropriate Vdc output
Installing a resistor of the appropriate value for each diode so that all Vf are equal (this seems counter-productive to me, will lessen the number of diodes, and increase heat and waste.)

I'm fairly ignorant electronically, so any help is welcome!


texts: Where can I find the C/W rating for PI48, PI49 and PI51 heat sinks?

texts:
I was wondering if there is any reference to calculate the C/W ratings for PI48, PI49 and PI51 heat sinks? Just for reference, I am referring to these devices:

http://www.nex-robotics.com/heat-sink.html

I am not even sure if PI48, PI49 and PI51 are standard terms. Also, I think the C/W values would change for different lengths.

Thanks!
Abhishek


texts:
I want (have) to use  external SRAM on my STM32 and want to have in total 16Mbit.
Because big SRAM is quiet expensive, I want to use 2 smaller ones.
The question is, how do I achieve this (google is no big help in this case :/ )

My idea was that I use the 19 Adress lines for the first SRAM Chip and then for the second SRAM chip I use the lower 18 + 20th Adress line, so this memory scheme applies:

SRAM1: 0x00000 - 0x7FFFF
SRAM2: 0x80000 - 0xFFFFF

plus Offset of course ;)

The last thing is the Chip select line, but I can achieve this with a simple NOT-Gate

CS1 = ¬A[19] (indexed zero)
CS2 =  A[19]

Does this work? I'm concerned about rise and falltimes and delay from the gates. Does anyone have ever thought about this or even have experience?


texts: Can the two same current monitoring ICs give different results?

texts:
Have trouble testing of 30 pieces INA250A4PWR circuits like below. Produced as PCBA.

According to test results 21 out of 30 have mainly 1.98 V/A gain ratio.

But, 9 out of 30 have mainly 1.55 V/A gain ratio.

Question is, is it an ordinary situation if not what am i missing?

These are the gerber views:

Top:

Bottom:

This is what the PCB looks like:

I'll send you detailed test results when possible.

Edit: 25.03.2020

The supply current is DC. For a quick test that can reveal the problem, we chose two subjects to represent the perfect circuits(Sample 1 and sample 2) and two subjects to represent the circuits that we thought were defective(Sample 3 and sample 4).

This is the test result of four INA250A4:

Note: The supply current is DC.

And these are the test subjects:


texts: Voltage Measurement through Spectrum Analyzer

texts:
I have done some measurements with a Spectrum Analyzer of a square wave of 100kHz and amplitude equal to 1V. The resulting power spectral density is here shown:

The highest peaks represent the odd harmonics (even harmonics are very low since the input square wave is approximately odd). Peak values are expressed in dBm. Now my question is: how can I evaluate the voltage amplitude of the peaks?

I have done this reasoning. My signal generator has an output impedance of 50Ohm, and the Spectrum Analyzer has an input impedance of 50Ohm. This means that the equivalent circuit of the measurement is this one:

Let's consider the first peak: since 4.62 dBm corresponds to 2.52mW, I have done the following computation:

where the term 1/2 is due to the voltage divider between the two resistances of 50Ohm, and 1/sqrt(2) is due to the rms value. But the result of this computation does not agree with the ideal computation of the fourier transform of my square wave. In fact, the first peak of the fourier transform should be equal to:

2/pi = 0.64V

This last computation is due to the fact that the Fourier Series of a square wave is:

and so the first peak of the fourier transform is 4/pi * 1/2, since the Fourier transform of a sine is proportional to 1/2 * delta dirac.

Where is the mistake?


texts:
I'm designing a circuit that will open a chicken coop when the sun comes up. I've attached a bungee cord to the door which opens the door when a pin is released. This pin is released by a car door actuator: http://amzn.eu/9r2gjnP

To power the actuator I've picked up a solar panel: http://amzn.eu/e3XX7WB this doesn't have the current to power the actuator so I'm thinking of pairing it with a rechargeable 9v battery.

I've come up with this but am not an expert by any means so would really appreciate it if someone could sense check it for me?
 Falstad Simulation

The idea is that the sun coming up triggers the LDR, this triggers the 555 timer which in turn allows power to flow to the actuator for a couple of seconds. I may have overcomplicated it so welcome opinions! :)

UPDATE 10/07/2018 15:00 (BST)

Based on feedback from @Chris Stratton and @brhans

Updated schematic: Falstad Simulation V2
The battery I was looking at: http://amzn.eu/6SgbNqA

UPDATE 13/07/2018 21:13 (BST) - Lower tech solution

So I decided to go with @Drew's suggestion of a lower-tech solution. However, I've run into a problem. My relay is simply making a buzzing noise when I expose the LDR to light. Is there a fundimental mistake in my circuit design? Falstad Simulation V2


texts: Applying an oscillation to a DC voltage?

texts:
I've lost a 555 IC that I had owned, so thought I'd make an relaxation oscillator for practise out of an operational amplifier:

The example of the simulator I have been using creates a square wave quite nicely, however there is no battery or current attached to it.

Is it possible to apply this, or amplify it with a DC current from a small battery so that it can be more useful in terms of powering something with a current? (i.e. a solenoid)

I seem to remember people putting an AC voltage source behind a DC source to have it risen (ride) on the DC voltage.

I am unsure weather to use a transistor or what!

If I am able to, how would I safely handle the inverse current (- peak of the square wave) if connected to a battery? Would it damage it? Would I have to redirect that portion with a diode or possibly have to lose it if I am using a transistor? Two transistors to handle each direction separately?

Edit: Adding a non-inverting op-amp circuit after the output seemed to in simulation jump 5 to 15 volts, and allow a current (150mA), however that current is coming from "nowhere" (ground and out a resistor to ground again) so I am unsure it could provide any real power.


texts: Buck/boost output voltage manipulation via feedback node

texts:
I'm designing an emitter follower circuit attached to the feedback node of a Buck/Boost SMPS in order to pull current out of the node and subsequently increase the output voltage by varying a DAC voltage, as described here: http://www.ti.com/lit/an/slva861/slva861.pdf. Here is the circuit I've been testing:

simulate this circuit – Schematic created using CircuitLab

Where NODE2 is the Feedback node on the Buck/Boost (VFB).

Originally, the resistor divider on the feedback node was R3 = 280k and R5 = 20k, in order to achieve a voltage of 800mV. However, I need an output voltage range of 1V to 14.4V and pulling current out of the feedback node only increases the output voltage. So I replaced the resistors to achieve a starting output voltage of 1V. I found my current resistor values using the following equations:

Where Req is:

I built the circuit on breadboard and replaced the Vout/VFB voltage divider with a 800mV power supply signal (since the Buck/Boost will keep the signal at 800mV). And tested the emitter voltage at 500mV increments of VDAC. Here are the results (note that I used a emitter resistor value of 1180 instead of 1194 in the actual test):

My question relates to the operation of the BJT in the context of this circuit. The emitter voltage varies fairly linearly with the DAC voltage, which is expected. However, I did not expect the voltage at the emitter to get any higher than 800mV (the voltage at the feedback node.) I was also trying to operate the BJT in its forward active mode (where VCE > VBE), but it looks like I'm operating outside of that range as soon as VDAC goes above 800mV. So what mode is the BJT operating in? Why is the voltage at the emitter greater than 800mV?

Apologies for the long report! Any feedback and thoughts are welcome!


texts:
My mom had an old Roku that she no longer wanted so I took it figuring I might be able to hack it and run a generic Linux on it. I took it apart and saw two headers that looked like they might be for debugging. I found the ground (on what I'm calling pin 2) and then probed the rest and found out they are all 3.3V (at least on P12). I hooked up my logic analyser to all the pins and rebooted, found a 115200 baud signal on what I am calling pin 6. Looking at the data it says "U-boot..." then "Linux 2.6.4-roku..." so I think I have the right pin.

My question is how could I go about finding the RX pin? I have a Raspberry PI which has a 3.3V uart and one of these https://www.sparkfun.com/products/9873. Is there a safe way to do it? Is there a standard header that has 10 pins with ground on 2 and tx on 6?

In the pictures I left the logic analyser hooked up. https://imgur.com/a/UL80fPe


texts: How does flux work, chemically, and what are the products?

texts:
Ususally, electronics solder comes with a built-in flux core. Among the solders I have laying around, I have a silver/tin solder with an "F-SW-21" flux core (ISO 9454-1: 3.1.1, this is zinc chloride and/or ammonium chloride), and a lead/tin solder with a rosin flux core.

As far as I know, these fluxes are there to "break up" the oxide layers on the metal surfaces. But how does this work, chemically? What are the products of this reaction, and where do they go? I am especially wondering about the voids that can form inside the solder: Are these mainly due to gaseous flux that simply boiled due to high temperature, or are these gaseous products of a chemical reaction?


texts: How are new 'best performance in the world' devices measured?

texts:
Say you build an ADC or a DAC (or a scope/spectrum analyser) that has the best performance in the world. With what exactly do you test it with?

I'm guessing:

Build the best ADC. You'll get digital numbers that you can collect, then run them through an FFT on your computer. But how do you know if your source or your ADC is the weak link if you get disappointing numbers?
Build the best DAC. As long as you've a better ADC, you can use the ADC to measure the DAC.

Am I thinking along the right lines?


texts: How do I design a microgrid using Simulink?

texts:
I have to do a project in which I have to model a microgrid which is controlled by using reinforcement learning techniques.

In doing so I have a problem, because I study control systems and I don't know how to model a microgrid using Simulink or Simscape.

I need to have in my model of the microgrid a solar panel, some buildings and a storage system, but I have no idea how to model them and searching on internet there is not much, and what I find is not clear since it expect to know a lot of concepts I don't know.

Can somebody help me understand how to model such microgrid?


texts:
I am new to Arduino so, bear with me. I am trying to make a project for a counter countdown using my Arduino Uno whereby any of the 1 out of 14 pushbutton has been pressed, it decreases a digit number on a seven segment display. & when the pushbutton is not being pressed, the number will increase. So that when all the 14 button is being pressed, the display will show 0. When all of the button is being released, it will show 14.

Also I need guidance on how to install the seven segment display on the Arduino Uno.


texts: Is it normal for a lithium ion battery to read with a very low voltage on a multimeter?

texts:
I have a PS Vita and I suspect the battery is dead and needs replacing, as the Vita won't charge at all. But the issue could also be the charge circuit, as when plugging it in to charge the charging light doesn't even come on.

I've disassembled the Vita and removed the battery, which is a Sony SP65M 3.7V 2210 mAh Li-ion pack. It has 3 connectors: positive, temperature, and negative.

I suspect that the battery may be damaged from being left discharged for an extended period of time. I'm using a multimeter to measure the voltage across the + and - connectors, and I'm seeing a voltage of 20mV.

Does this mean the battery is dead, or am I jumping to conclusions? Is there any reason why I might see a voltage reading like this on a healthy battery?


texts: Where's the energy in simulated caps/coils?

texts: I understand that you can use a gyrator to simulate capacitors or inductors with (very) high values. A capacitor stores its energy in an electric field, an inductor in a magnetic field. Where is the (high?) energy of a simulated 10H inductor? The gyrator doesn't even have to have an inductor. This gyrator simulates an inductor of 1H for every 2\$\mu\$F.


texts:
I have a device with a thermal fuse in it. The fuse has failed, and I would like to replace it.

Does thermal fuse have a polarity, similar to an electrolytic capacitor, or is it the same with normal fuse? It has a stripe marking on it.

Is it sensitive to polarization, or will either way work?


texts: How does an active device work as an oscillator when its output is fed back to the input?

texts:
In the book The Art of Electronics by Paul Horowitz and Winfield Hill, it is mentioned that "Device with power gain are distinguishable by their ability to make oscillators, by feeding some output signal back into the input". I have two question regarding this statement.

Is this statement complete in itself? Is there no need of another circuitry(let's say a filter)? If yes, what causes the oscillation in such a feedback circuit which contains only an active device?
Is it true for all device which can produce a power gain (that is active devices)?


texts: Having issue with draw timing diagram for logic circuit

texts:
Hey all! This is a question for draw a timing diagram for the circuit I was try to do it, but I don't understand what is the first input should I use then go through the whole circuit.

Can anyone explain to me step by step that would help me a lot! By the way I know the basic things about timing diagram and flip flop.


texts: Measuring current using ACS712 interfaced with ESP8266

texts:
I'm using ESP8266 interfaced with ACS712 current sensor to measure current and voltage.

However it displays some values without any load being applied, and after applying the load, the changes are not that much (about 0.06).

Below is the code:

//Measuring Current Using ACS712

//#include <Filters.h>            //This library does a huge work check its .cpp file
#include <Adafruit_GFX.h>       //OLED libraries
#include <Adafruit_SSD1306.h>

#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels
#define OLED_RESET    -1
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

const int sensorIn = A0;
int sensitivity = 66; //  66 for 30A Module
int adcvalue= 0;
int offsetvoltage = 2500;
double Voltage = 0; //voltage measuring
double current = 0;// Current measuring

void setup() {

 Serial.begin(9600);//baud rate at which arduino communicates with Laptop/PC
 display.begin(SSD1306_SWITCHCAPVCC, 0x3C); //Start the OLED display
 display.clearDisplay();
 display.display();

}

void loop()
{

 adcvalue = analogRead(sensorIn);//reading the value from the analog pin
 Voltage = (adcvalue / 1024.0) * 5000; // Gets you mV
 current = ((Voltage - offsetvoltage) / sensitivity);

 Serial.print(adcvalue); //prints the results on the serial monitor

 delay(2500);
  display.clearDisplay();
  display.setTextColor(WHITE);
  display.setTextSize(1);
  display.setCursor(0, 20);
  display.println("Voltage");
  display.setCursor(50, 20);
  display.println(Voltage);
  //display.setCursor(75, 20);
  display.setCursor(85, 20);
  display.println("V");
  display.setCursor(0, 30);
  display.println("Current");
  display.setCursor(50, 30);
  display.println(current);
  display.setCursor(75, 30);
  display.println("mA");
  display.display();

 Serial.print("\t mV = "); // shows the voltage measured
 Serial.print(Voltage,3); // the '3' after voltage allows you to display 3 digits after decimal point

 Serial.print("\t current = "); // shows the voltage measured
 Serial.println(current,3);
}


texts:
A question on SCR/thyristor voltage rating: For SCR rated at 100A 400V.

i.e. It seems common the rated current can take 10x more surge current so 1000A surge for 100A SCR without damage.

Can also the listed 400V take much larger surge volts for a short time?
If not 10x then at least 2 or 3x?


texts: Why in a PMOS transistor VDS has to be negative?

texts:
I can't understand why it is required that VDS is negative in a PMOS transistor while it must be positive in an NMOS.

Thanks


texts: Stepper Motor H Bridge High Side N-Mos Burn Problem

texts:
Last year, i designed a stepper motor driver card with DRV8711 and CSD17506. I am driving my stepper motor with Vm=24 Volts and motor current Im= 2.14A. Texas Instruments gate driver drv8711 is driving both high and both sides. The design schematic values are same the as DRV8711EVM user guide. Here are my H-Bridge schematics.

My company is using this card in our products and at least 100 cards worked great and there was no problem until new Mosfets arrived. We get these mosfets from digikey.

The problem is, when I powered 'MOTOR', one of the high side Mosfets burn suddenly, some of them are working for 1 second and some of them are working for 2 hours, but all of them are burning in the end. Only high side mosfets, and mostly Mosfet1 in schematic.

I first thought about soldering, and solder mosfets with special care and problem decrease but not removed.

I thought about if there is a problem about components and ordered new ones from Digi-Key again and the same problem occurs. Resistance of drain and source of burned mosfets are nearly 0\$\Omega\$.

Next I thought about if there is a version change in CSD17506 but could not find any change in the datasheet or on Texas Instruments forums.

When I solder older ones they are working well, but the new ones are getting damaged.

Then I thought about using gate resistors.

Results:
Gate resistors at only at high side mosfets gates = 20\$\Omega\$. The problem continued but worked for only a little longer.

Gate resistor at all mosfets gates = 240 \$\Omega\$. Problem solved but mosfets generated a lot of heat and step motor is vibrating and working a bit noisy and vibrating. While motor driver enabled any driver keeps stepper motor at a position there is still noise.

I measure VDS of mosfet while driving my motor, it sometimes reaches 30 V.

One of TI experts recommended that I change my mosfets to 60 V. I changed my mosfet and problem removed. And also he recommend me to use gate resistors only at high side no larger than 20 \$\Omega\$. And also extend the dead time but dead time is already at its highest value which is 800ns

Although I solved my problem with 60 V rated mosfets, the main problem is I have approximately 1500 Mosfets and each cost $3. I need to use them in some way.

I already used 20 \$\Omega\$ at high side but problem decreased but continues.

What can you recommend me?

What can be the main reason?

I also thought to use flyback diodes at mosfets but I dont have any space to use any additional diodes at mosfets on my PCBs.

Can you help me to find and solve the problem?


texts: I have a defective 120 Ohms 3 watt resistor that needs replacement. My place have 120 ohms with all available wattage except for 3 WATTS. I have checked online but they don't sell 120 Ohms 3 Watt. I am thinking of combining 2 or 3 resistors to get the value of 120 Ohms 3 watts. The problem is with the connection. I don't know how to do it. I have made some research but they are using formulas in their discussions which I couldn't understand. I am seeking help from anyone who could give me the right resistance, wattage and connection (series/parallel) so I can get the exact resistance value and wattage. Thank you in advance.


texts:
I have an ebike which I installed some cheap lights on just so it's legal for the time being.
I have received the components to make a light that works off of the main battery. The issue I am having is when I try to plug in the 35-60V to 12V converter, there is an initial spark.
The battery mount doesn't have anti-spark connectors and I don't think I could modify it to have that. Reading on the internet I found out that using an inductor would cause unwanted voltage fluctuations.
I am trying to think of a way to make a timed resistor system whereby when the bike's battery is plugged in only 5 amperes can flow through the converter circuit before the resistance is taken away.
I don't know if that's possible and I would just like to hear about some possible solutions.


texts: In one of the answers on this site, I found link to this project. That article mentions internal resistance of batteries and cells. Where can I find data about common ranges of internal resistances for batteries? I've always heard that it's low, but I couldn't find anywhere how low is low and common resistances for common battery types.


texts: Confusion over binary radix usage and formatting through FIR filter (and circuits in general)

texts:
I'm having a bit of a hard time trying to get my head around binary radix's. Specifically when it comes to use them in a circuit. On their own I can understand them fine. For example, 2s complement, fixed point, BCD etc..

This is where I'm getting confused.

I've been building a FIR filter in VHDL and have come to the point where I have to implement the coefficients.
Each coefficient is below 1 and is 9 bits. The numbers are signed fixed point numbers. The first 8 bits are the fractional part with the 9th bit the sign bit / integer bit.

Now my problem is: now that I have chosen a format (say, 8 bits for fractional part of the number), does that mean every other number I choose to input into the system have to follow the same radix? Fixed point with 8 fractional bits?

As what I'm being told is, when you input an impulse response to the filter the output should be each coefficient in order. When I use "0000000001" as the input then yes I do get each coefficient on the output. But I don't understand how. I understand that a '1' is getting clocked through each stage and being multiplied with each coefficient on each clock but it doesn't represent a "1" in the same format or radix as my coefficients. A true 1 would be "0100000000" as the first 8 bits are fractional.

I'm having a hard time getting my head around the number side of system, the structure and how it's supposed to work.

Is there something wrong with my understanding?


texts:
My old multimeter, with all through hole components had an accident (I was measuring current on the 10A unfused range and then decided to check the voltage of the a lead acid battery) with one large carbon resistor glowing and melting and another through hold low value 1 Watt component suffering failure. Everything works apart from current measurement.

Can anyone identify this resistor (I cannot measure it as it has fused).

I have checked various sources and this value doesn't appear in any of the E... series. I think that the colors are blue silver white and gold and suspect that is is a sub 1 Ohm value part as it was used as a shunt for < 0.5 Amp measurements but I have never seen a dark green resistor before (I think that this would be early 90's vintage).


texts: Is it OK to trickle charge a disposable battery

texts:
So I am playing around with designing a UPS when another question hit me.

If I have a source feeding a small amount of current into a non-rechargeable battery is this OK?

By OK, I mean is this acceptable as a circuit to be put into products.

The battery will self discharge and begin to receive very small amounts of leakage current. After reading a bit I was surprised to find that you can actually recharge non-rechargeable batteries(disposable).

What scared me: Wikipedia quotes, "manufacturers do not support recharging, and warn that it may be dangerous". So this of course makes me worry about using this simple circuit. My intention is for the consumer to not use a rechargeable battery.


texts:
Reading the datasheet of the MAX17055, I found on page 11 the following example circuit:

It clearly shows a ground symbol at the CSP pin. As far as I understand, the IC directly connects to an external load with SYSPWR to VCC and SYSGND to GND.
Since this would imply that the sense resistor is also grounded at the other side, its voltage sits at 0V. The resistor's purpose is the measurement of current flow across itself.
But how is this possible when both ends are already at 0V?


texts: Is there a difference between TI brand of the 74HC595 and the NXP brand?

texts:
I have been trying to figure out the functional differences between TI's version of 74HC595 and NXP's version. I've been looking at the function tables in the datasheet for TI and the datasheet for NXP but am having a hard time determining if the function tables are equivalent. They have the exact same number of states and seem to be very similar. The confusion is arising from the fact that some values that are L or H in one table are X in the other table and that TI's version is missing the output columns.

If someone is able to figure out if these two chips are functionally equivalent, i.e., they do the same thing given the same input signals, I would appreciate some help. Thanks.


texts:
I'm wanting to replace 4 su'scon 1000uF 16V capacitors. I believe they just failed due to having bad ripple rates (internet searching).
They are also marked 1519(m). I found some Panasonic fm low voltage capacitors that match! But I don't honestly know what the fm is for, or if it might not be for a tv?
I assume the low voltage isn't an issue because this board seems to control all of the power up stepping 24v and down to 1A.


texts: Streaming live video from a camera to a display using two arduino UNOs

texts:
My question is pretty much in the title. Is it possible to send live video from a camera connected to one arduino uno, to another arduino uno with a monitor connected? (Via wifi, Bluetooth, radio, etc.) Will they have enough processing power and can any simple data transfer methods allow such large amounts of data? Please inform me on the details if this is possible, or if not possible, explain other ways using a similar setup.
Thanks in advance.


texts:
I made H-Bridge circuits with HIP4082IB & FDMS86101.
It works good with 30V power, But some low-side FET & gate-driver die when 70V applied.
Load is stepping motor, But problem even in without load.
2.4K discharge RES between G-S, No snuber.
I tried feed 12VDC to gate driver first, and 70V for bridge next. The same bad result.
Sometimes only the low FET burnout. So I believe the FET die first, And the gate driver follow.
Also IRFP260 have problem too.
What is it that I missing?

Gate drive and MOSFET connected via 2.54 pin header.


texts: Can MQ-135 Gas Sensor be used to make DIY CO2 level monitor?

texts:
So I am thinking of building an device to measure CO2 levels in the air DIY fashion as premade equipment costs upwards of 100$.
I have found some information on how to build such a device using Arduino and a MQ-135 Gas Sensor.

Seeing how the MQ-135 sensor is about 5 bucks I was wondering if it would be able to actually measure CO2 parts in the air, as other CO2 specific sensors I have found are more in the hundreds of dollars price range.

Has the MQ-135 Gas Sensor already been used for projects like this?


texts: Footprints for SMD electrolytic capacitors

texts:
Does Altium Designer Summer 09 has footprints for SMD electrolytic capacitors? If so, where can I find them?

I've noticed the dimensions of these type of capacitors are given in diameter x height. How can I find out the dimensions of the pads, provided I don't have the datasheets for the capacitors?

Is there a standard for the SMD electrolytic capacitors' footprints?


texts: Understanding how PCB CAD designs affect the final product

texts:
I'm looking to design my first printed circuit board and having trouble understanding PCB CAD systems conceptually. I've started on schematics with EasyEDA, KiCAD, and Fritzing without finishing, as there is a lot of detail and it's rather unclear what's important. In software terms, I don't know which fields are code with an actual effect on the product, and what stuff is comments that's just there for human communication, or to make a drawing look pretty?

There are large libraries of user-contributed part definitions and I'm reluctant to use them because I don't know how to evaluate them. What does quality look like and what's going to screw me up if it's wrong?

I have hand-wired a couple of projects by cutting FR4 and drilling a lot of holes in a couple of boards with less precision than I'd like. I have a simple model of how an unsophisticated through-hole based board design should work, where if the holes are in the right places and there is connectivity between the right holes, this is what actually matters? But there seems to be a lot of other stuff involved in drawing schematics and maybe simulation, design rules and so on, and I don't know how much of it is important.

I'd appreciate any explanations or references to conceptual introductions you might know about.


texts: Is the wattage important when buying a replacement solder tip?

texts:
I have a Weller SP15N (15 watt) soldering iron which needs a replacement tip. It needs 3.5mm tips.

Replacement tips on ebay often come with what looks like a wattage rating.

Why do tips come with wattage ratings, and is that rating a max. rating? In other words, can I use a 30 watt solder tip for my 15 watt soldering iron?


texts: Isn't my ground different from the factory's ground?

texts:
My understanding is that ESD safety things (mats, wrist straps, specially marked soldering irons) are designed to bring everything that can touch a component to the same electrical potential energy – ground.

But it seems unreasonable to expect that there's no voltage between my desk and the factory where my components were produced.  After all, the factory is likely halfway across the world, and the resistance between here and there is significant.

So, say a component is carefully packaged and shipped to me in one of those little ESD-safe bags.  Before opening the bag, I carefully ground myself and my workstation.  Despite this, the component is destroyed as soon as I touch it because the ground that I tied myself to is much different from the ground that the component was tied to when it was produced.

What precautions are taken against this?  Is it just something that can happen in theory but that isn't an issue in practice?


texts: Howcome it is safe to assume the the voltages are equal in this picture?

texts:
For the below picture, howcome it is safe to assume the voltages are equal, despite being having different resistor setups. For example, to get from point A to C, it's a different path of resistors from point A to D.

Also, if the voltages weren't 0 or symmetrical, how would we deal with the pair of resistors around E?


texts: I am currently routing a 4 layer PCB and I was wondering how I connect the ground and power planes to the connector and components that need them. Do I simply leave the two planes without routing on them? If so how can a connection be created between those planes and the components.


texts: Will a higher voltage to get the desired current hurt RGB LEDs?

texts:
I have 29 RGB LEDs connected in parallel and will control them with PWM.
They can handle 20 mA per color. I was planning to supply them with 5V and measured the voltage drop per block at 20x29 = 580mA input 5V.

Blue drops 3.06V so resistor needed: 3.9 ohm
Red drops 2.15V so resistor needed: 5.6 ohm
Green drops 2.95 so resistor needed: 3.9 ohm

Combined resistance: 1.45 ohm
The cable is a common UTP CAT6 cable I merged the ends so 8m of wire and measured with 2 multimeters and it's 3 Ω. This is the problem. The total resistance is 4.45 ohm and that is max 1123 mA instead of the desired 1740 mA
Can I do a 9V supply to get the current with adjusted resistor values or will it hurt the LEDs?
They won't be running at ful power all the time, PWM will adjust the colors so power dissipation should not be an issue.
Unfortunately I can't find the datasheet. Part number EVERLIGHT EVL-504-90-CA


texts: Put saved data in flash of STM32 at the end of all other sections

texts:
I want to emulate EEPROM over flash of STM32F103. Is there a way to use all free flash instead of the only page? How can I initialize starting point of my EEPROM emulation so that it would be after all sections? I tried to add section after .text like

.text: ...

.myvars :
{
. = ALIGN(1024);
KEEP(*(.myvars));
KEEP(*(.myvars*));
} > rom

and define variable as

__attribute__((section(".myvars"))) static const flash_storage Flash_Storage = {
    .magick = "1234567890absdef0987654321",
    .all_stored = USERCONF_INITIALIZER
};

but it doesn't helps me: I see some more data after this structure in binary dump.

UPD: the solution of this problem quite simple. The section .myvars should be after last section in ram, i.e. after .data!


texts: What is the max current that this circuit can handle?

texts:
I'm making a simple project. For me, it is recommended that the output current is 1.5A. But it's OK if it is 1A or 0.5A.

For voltage regulator:

Datasheet says that the output current is up to 1.5 A.

Can I use this max current rating?

For diodes:

Datasheet says that the output current is 1A at a temperature of 75 deg.

In Egypt, the temperature is between 20 and 40 deg.

So, can the diodes handle 1.5A?

For capacitors:

I don't have their datasheet but I think capacitors can handle this current.

For transformer and fuse:

I have not bought them yet. I will choose them according to the answer of this question.
I would like to know the max current of the transformer and the fuse.

Thank you very much

simulate this circuit – Schematic created using CircuitLab


texts: Need help understanding this circuit (with LUTs, multiplexer and flip-flops)

texts:
The exact question is the following:

For the programmable logic block shown in Figure 5-13, show the necessary
configuration settings to implement each of the following types of circuits.
You can assume that the upper data input of each multiplexer is chosen with
a select input of 0.
(a) A combinational function of inputs a, b, and c.
(b) A Moore machine
(c) A Mealy machine

Figure is the following:

When it asks for the combinational function, I think it is asking about the truth table. And from that I can draw the moore and mealy machines too. But the problem is that I'm unable to figure out the outputs of the two LUTs. There are 4 combinations of inputs possible for each but what is the output value of each of those inputs?
I'm also unable to figure out the meaning of the vertical line in middle of the dotted box (labelled as addition logic).
Any help is appreciated.

(The question is from the book "Logic and Computer Design Fundamentals page number 321, 5th edition)


texts: Why won't this bulb light when I put the multimeter in series?

texts:
It lights here with no multimeter, this is fine

But if I replace one of those wires with the multimeter, connecting the multimeter in series, then the bulb doesn't light.  I am wanting to measure current of course, but from what I understand, the bulb should be lighting up. I am as you see, getting a 0 reading so for some reason the circuit isn't happening.

Here's another picture in case the above one wasn't clear enough

Why is the bulb not lighting?

The multimeter is able to measure voltage and resistance ok. I trued adding the wire, so the bulb lit, and putting the probes across the bulb and it measured the voltage, and I tried putting taking a resister and putting a probe on each leg and it measured that, so it's just this issue trying to measure current. I'm a complete newb so most likely I'm doing something simple wrong.

Added

One answerer mentions that I had the dial set to 10A.  I also tried the dial in 200m 20m and 2000 micro, and it still said 0 and the bulb didn't light.

Another answerer suggested a continuity test.. I am not entirely sure how.. one video on youtube showed showed a guy pointing his dial to what he described as a wifi type symbol and then tapping the probes together and getting a beep.. I don't see such a symbol and I don't get a beep on any setting of the dial.

Another answerer asked what model deviceI  am using.   UNI-T UT132A sold by maplin, uk.

Another answerer said the multimeter should be between ground and load rather than v+ and load. I have moved it as you see in the following pic though still the bulb isn't lighting.  I'll take it to maplin electronics store tomorrow and report back.


texts: How do I caluclate which capacitor to use as a filter after the brdige rectifier using the 18Vpk A.C. 50 Hz as a source?

texts: Like how would I go about on it? From calcualating the ripple voltage, to knowing which value of farads to use.


texts: Why voltage source has been connected via inductor at the output of LNA?

texts:
I have been reviewing the schematics of LoRaWAN Gateway designed by Microchip (Page 48). The output of the LNA has been connected to voltage source via inductor.

According to me, the LNA module doesn't have power input pin and it requires the power to operate. This particular LNA Module requires power to be applied to the output and the signal will be modulated upon dc voltage. The Inductor makes sure the frequency won't get pass to the power plane.

I found another schematics and a different LNA module (SAFEA1G58KA0F00). The LNA module again doesn't seem to have power pin and module has been connected in similar configuration (voltage source has been connected at the output via Inductor). See the picture below: (The picture is of SIM7600I reference design and the picture below shows GPS part of the design)


texts:
I am looking for formula and easy explanation for calculating the wavelength of a sine wave. So far I have not been able to calculate the example I want to do as I could not understand the resources I've found from Google.

What is the wavelength of sine wave? Given frequency, distance and time.

For instance, a 0.42 MHz sine wave takes 3.3 µs to travel 2500 meters.

I am asking for patience I know this might look amateur for some but I am learning basics and I struggle to find the answer.


texts: Chart a sine wave, then adapting it to draw a conclusion

texts: I have an unusual request and I am new to this.  I was doing an experiment where I was charting electrical values on a Lecher Line (a type of antenna that creates a standing radio wave).  I'm using 148.000 MHz.  I want to chart the sine wave using the details I obtain from an oscilloscope.  Then I want to predict the amount of voltage change that will occur if I were "stretch" or shrink the wave.  Any assistance would be greatly appreciated.


texts: How to electronically generate exponential and logarithmic functions

texts:
i mean, it is possible to generate with Op amps, or diodes, etc, to generate complex exponential and logarithmic functions, like one can create sinusoidal signals using a Wien bridge oscillator.

Thank you very much, if it does what devices can help me on that?


texts: What is the advantage of an advanced battery charger?

texts:
Since my old, dirt cheap battery charger broke down, I disassembled it and was surprised not to find any integrated circuit in it:

Obviously, I'm now looking for a replacement. Now, there are advanced battery chargers which advertise:

    ... provide longer lasting, better performing batteries ...

But I'd rather ask in this community: What are the specific advantages of the more expensive models? I guess they're limiting the charging current? But if they only inform me on fully charged batteries I'd rather stick to the cheap chargers.

I'm slightly unsure if this is the right place to ask such a question (it sounds like buying advice) -- let me know if not.


texts: How to determine the most appropriate DC amplification value for a BJT?

texts:
The BJT diagram is shown below:

The voltage source at the base side is increased incrementally from 1V to 10V, with the voltage source at the collector side being constant.

The Beta values are recorded in OrCAD PSPICE tool:

1V - 147
2V - 168
3V - 174
4V - 176
5V - 177
6V - 176.9
7V - 176
8V - 174
9V - 173
10V - 158

The beta value increases from 1V and reaches its peak around 5V, and it starts dropping from there till 10V. I want to find the most appropriate DC amplification factor from these values, which will mainly be used in doing the DC analysis of a common emitter BJT amplifier circuit. Do I assume that the most appropriate value of a DC amplification factor is the mean value of all the beta values from 1V to 10V, or? Am a bit confused here.


texts: Altera Quartus not creating symbol files

texts:
I'm looking to create a schematic block from a vhdl file in Altera'a Quartus software.

I've been using File->Create/Update->Create Symbol Files for Current file

The file compiles okay and I get the following message:

with the following warnings:

Warning (10445): VHDL Subtype or Type Declaration warning at fixed_pkg_c.vhdl(1470): subtype or type has null range
Warning (10445): VHDL Subtype or Type Declaration warning at fixed_pkg_c.vhdl(1471): subtype or type has null range
Warning (10445): VHDL Subtype or Type Declaration warning at fixed_pkg_c.vhdl(1472): subtype or type has null range

What I'm expecting to find is a .bsf file in the project directory that I can then use to create a schematic block.... but it doesn't appear (I've searched entire hard drive).

1. Am I correct to expect that a .bsf file has been created?

2. What debugging/troubleshooting steps should I take?

Quartus II 64-bit v13.0.0

EDIT:

here's the code:

library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
library floatfixlib;
use floatfixlib.fixed_pkg.all;

entity gate_zero_initiato is

    port(
        power_on      : in std_logic;
        E1_A      : out std_logic;
        E2_A      : out std_logic;
        E3_A      : out std_logic;
        E4_A      : out std_logic;
        E5_A      : out std_logic;
        E6_A      : out std_logic;
        E7_A      : out std_logic;
        E8_A      : out std_logic

    );

end gate_zero_initiato;

architecture behavior of gate_zero_initiato is

begin

    powerup:process(power_on)

    begin
        if (power_on'event) then

                E1_A <= '0';
                E2_A <= '0';
                E3_A <= '0';
                E4_A <= '0';
                E5_A <= '0';
                E6_A <= '0';
                E7_A <= '0';
                E8_A <= '0';

            end if;
    end process powerup;

end behavior;


texts: How instructions get executed in a pipelined architecture?

texts:
I saw this HW solution in CMU Comp Arch course website. I am reading ComputerArchitecture on my own. I just have a doubt.

Here is the HW question:

Given the following code (MIPS):

MUL R3, R1, R2
ADD R5, R4, R3
ADD R6, R4, R1
MUL R7, R8, R9
ADD R4, R3, R7
MUL R10, R5, R6

Fetch (one clock cycle)
Decode (one clock cycle)
Execute (MUL takes 6, ADD takes 4 clock cycles). The multiplier and the adder are not pipelined.
Write-back (one clock cycle)

Calculate the number of cycles it takes to execute the given code on a pipelined machine with scoreboarding and five adders and five multipliers without data forwarding.

Here is the actual solution:

My doubt:

Why the second instruction ADD R5, R4, R3 is in decode state two
times? (in 3rd cycle and again in 10th cycle)
Why the third instruction ADD R6, R4, R1 did not do its DECODE state
4th cycle?


texts:
Here is a simple dickson inverter:

The simulation shows this:

Is it a problem with the simulator? I don't see why the capactior was charged to the voltage of the square wave signal? Why is the push-pull pair not working?

UPDATE: I have replaced the push-pull pair with a single NPN transistor, as suggested.

 It works as expected, but the current is limited.

Is there a way to do this without a series resistor and single supply? (E.g. eliminate power disciplation on the resistor).

UPDATE: finally! Frequency increased to 100K, voltage source drives a voltage amplifier, and then the push-pull pair.

Simulation result:

Frequency had to be increased because the load resistor was changed to 100 ohms. Now it can deliver about 150mA. Great!


texts: I am currently working on a circuit where we read the time it takes for a capacitor to charge depending on the load. I would like to know what is the purpose of the first stage with Q1 and Q2. I also have a problem with Q2. The transistor is always ON, even when Vin is 0V.


texts: Somebody could help me to understand the first question? I am struggling to build the equation to solve it


texts: What does the gain of a non inverting OpAmp depend on?

texts: I know that it does not depend on the output impedance of the voltage source, but can it depend on the input impedance of the amplifier?


texts:
Is the LEFT circuit of darlington pair, equivallent to the RIGHT transistor circuit?

Is my asumption true?
I replaced the two transistors in darlington pair with one; having beta equal to the product of betas of the two transistors, and the voltage from of 1.4 (0.7+0.7) across Base and Emitter.

Then I am calculating the Ib and hence the Ic.
In practical experiments, I found that my calculations are not very exact, but close enough.

For example, for the circuit to the right I found:

Ib = 63 nano Ampere
Ie = 4.5 mA

In measurements, I am finding the Ie about 5.5 mA.


texts:
I am working on the development of a low-cost capacitive soil moisture sensor which uses dielectric permittivity changes to estimate moisture.

I want to use FDC2214 for Cap to Digital Conversation. Is this suitable for soil moisture sensing?

FDC2214


texts: PCB Mount Push Button Identification Help

texts:
Can anyone help me identify the push button on this PCB board taken from a router? The button is circled in RED and is the one on the backside of the router, used to turn it on/off.

I would like to use it in my circuit but don't know what it is called.


texts: Can power actually be sent into the ionosphere for transmission?

texts:
I always was amazed by a great man named Tesla. I have looked everywhere to see if I could get the truth of what he actually did but I just don't know what to believe. I don't what to trust, what to take as just a "false conspiracy" and how to get evidence.

Tesla brought the Radio, and the AC system and many other amazing electronics to the world, and his claims extended very far. I just don't know where to stop believing in his claims and where to know what was true or not.

One big controversy topic that I am particularly interested in is this. :

I have read a book , seen many articles online, and watched this all agreeing that this method can transmit power without power lines.

If any of this is even true, what methods would Tesla have been using to achieve this and why is his work never referred or attempted many years later?

Is it only because the electric companies are "money hogs" and don't want any of this?

Or is it because it is unsafe?

Or is it just totally some false claim that Tesla said and just built a tower for no purpose spite all of his experiments in Colorado springs?


texts:
I am trying to learn how to use "new" HAL library from stm32.
When I try to do simple ADC conversion it works just one time, but then it stops converting. I suppose End of conversion flag does not get set. I am using STM32f429I Discovery board, which has STM32f429ZI on board.
Note that I know about sprintf being bad practice and making adc with interrupt is better, I know that, please don't point it out, this is not relevant to the question, I am just testing HAL here.
So the question is why EOC flag is not set or what could I do to make it work? Googling is not helping much since very few good materials about HAL out there.

Here is the code:

__IO uint16_t ADCValue=0;
void HAL_ADC_ConvCpltCallback(ADC_HandleTypeDef* hadc);

int main(void)
{
  char str[15];

  /* Various initializations */

  HAL_ADC_Start(&hadc1);
  while (1)
  {

        if (HAL_ADC_PollForConversion(&hadc1, 1000000) == HAL_OK)
        {
            ADCValue = HAL_ADC_GetValue(&hadc1);
            sprintf(str, "%d", ADCValue);
            BSP_LCD_DisplayStringAt(130,30, (uint8_t*)str, LEFT_MODE);
        }

  }

void HAL_ADC_ConvCpltCallback(ADC_HandleTypeDef* hadc)
{
    ADCValue = HAL_ADC_GetValue(&hadc1);
}

I also created the project with CubeMX, adc configuration is the following:

EDIT 1
I tried to debug everything and it seems that program gets stuck into checking for EOC flag - it sees that it is not shown and therefore issues timer waiting for EOC to show up(but it never gets set)
Here is the code where it gets stuck in debugger:

/* Check End of conversion flag */
  while(!(__HAL_ADC_GET_FLAG(hadc, ADC_FLAG_EOC)))
  {
    /* Check for the Timeout */
    if(Timeout != HAL_MAX_DELAY)
    {
      if((Timeout == 0)||((HAL_GetTick() - tickstart ) > Timeout))
      {
        hadc->State= HAL_ADC_STATE_TIMEOUT;
        /* Process unlocked */
        __HAL_UNLOCK(hadc);
        return HAL_TIMEOUT;
      }
    }


texts: Difference between the words 'die' and 'chip'

texts: In some articles speaking about the IGBT power modules, we can see that the word 'die' has been used for calling the semiconductor component of IGBT device. However, other articles calls it 'chip'. Similarly, the solder layer which connects the semiconductor component to the beneath substrate is called either 'die attach solder' or 'chip solder joint'. Accurately, which word is correct for the semiconductor component of the IGBT power modules? Die or chip?


texts:
I came across valve regulated lead acid batteries with the capacity rated as 112w at a 30 minute rate.
Im not sure what this means. Can anyone please help me further understand this method of rating.


texts: Solenoid control with current limiter - is it correct?

texts:
last year, I designed a solenoid control board which is still working very well.
The board was based on ATmega328p and used an optoisolator 6N136 to isolate the high power from the low power and I used a MCP1406 as MOSFET driver for the FQP30N06L.

Now, I would like to update my board by adding a current limiter in order to set the maximum current to 2A.

I saw the Maxim 17525 Adjustable Power Limiter and I tried to integrate it in my previous design. I did the connections in this way:

SETI: I connected a 18.7k resistor to SETI output to limit the current to 2A as specified in table 3 at page 18 in the datasheet.
CLTS1 and CLTS2: I left unconnected the port CLTS1 and CLTS2 to set the continuous mode as described at page 13
OVLO: I connected a 100k resistor to OVLO port to set the overvoltage to 27V as reported at page 12
UVLO: I connected a 340k resistor to UVLU for undervoltage (9V)
OUT: I connected the output of the device to the drain of the MOSFET.

The solenoid can work at 12VDC/24VDC at 2A.

I'm a beginner, so I'm pretty sure I did lots of mistakes with the connections.
Can you please give me some advices?
How can I correct the circuit?

Thank you!


texts:
I have a device which runs on two AA Duracell batteries. The batteries (brand new) together produce 3.2 volts (1.62 volts individually), which is estimated to run for at least 2 years. The device is always running and consumes 300 micro amperes, which isn't a lot.
Could someone tell me how long can the batteries will last on 3.2 volts (1.62 volts individually) before dropping to 3.0 volts (1.5 volts) in years/months/weeks/days/hours/minutes? So basically, how long until the batteries voltage begins to drop?


texts:
I am in the process of designing a custom vaporizer.

So the main coil with a resistance ranging from 0.2 Ω to 2 Ω is switched using a MOSFET shown in the circuit diagram below. The system is powered by 2 cells of Li ion.

My main problem arises when I try to include a feature to measure coil resistance (this is quite helpful while building coils and for overall safety of device). Below is the circuit diagram that I thought of. In black is primary switching circuit. In green, proposed circuit to measure resistance.

According to my research the way to go about impedance measurement is to use a constant current source to find the voltage drop. This would be okay to include in my circuit if I was using a p-channel MOSFET. But due to low available options, high current consideration I cannot go with a p-channel.

I am currently thinking of using a constant current source to draw current through the coil into a dummy load (drawn in green). Then measuring the voltage drop across the coil to estimate the resistance.

My questions are,

Is this an acceptable/safe way to use the current source?
If yes, do I even need a dummy load or can I just short to ground?
Is there any better way to measure it?


texts: How do I find a short in an unpopulated 4-layer PCB?

texts:
I have a 4-layer PCB, designed in Eagle CAD 6.5. The stack-up is:

Signal
GND (ground)
DVDD (digital power)
Signal

GND and DVDD are solid planes, with vias connecting them to layers 1 and 4.

I have 4 PCBs. Three PCBs are bare - unpopulated, fresh from the fabricator.

In the bare boards (and the assembled one) there is a short between GND and DVDD. It could be a manufacturing defect, but since all 4 boards are bad, it's more likely it is a design problem.

I've manually examined the gerbers in gerbv to see if there are vias that connect to both GND and DVDD, but did not see any. But there are a lot of vias, so I could have missed one.

I've done an Electrical Rule Check (ERC) and Design Rule Check (DRC) - to look for problems. I get no unapproved errors. I've examined all the approved errors to look for problems - there are no overlaps.

How do I find the source of the short circuit?


texts:
I'd like to build a lamp for my girlfriend's birthday. The lamp would change colours if she touches the lamp base.

My idea is to use Arduino Nano as the "intelligence" and a line of sensors under the base (which I was thinking of making out a piece of thin wood/bamboo).

What's the best sensor (capacitors? no clue) that would actually pick a signal up from under a manually engineered "wooden" surface?


texts:
After studying timing analyzing in FPGA I still have some confusions about time borrowing like the following:

I have seen some of this site EE having good reputation saying that time borrowing is only for VLSI not FPGA while in Quartus document explaining timing constraints time borrowing is discussed.

Does time borrowing need any configurable material? In fact, what I first understood is that the fact of considering latch with level instead of edge sensitive clock is sufficient to benefit from time borrowing since if for instance we have latch1 sensistive to level 1 applied to latch2 sensitive to level 0 then if the combinatoric circuit in latch1 has a delay higher than the level 1 width but the combinatoric circuit in latch2 has delay less than the level 0 width minus what exceeds from latch1 circuit than timing constraints are ok by time borrowing. What is more confusing for me is that I have found a Patent on a configurable delay for time borrowing (so added hardware needed).

Could someone explain this to me please.


texts: current amplification of a circuit containing a transistor

texts:
I'm having trouble with a BJT circuit.

What we are given:

\$U_{CC} = 10\text{V}\$
\$R_C = 972 \Omega\$
\$R_B = 14\text{k} \Omega\$
\$U_{\text{BE}} = 0.7\text{V}\$
\$I_C = 12\text{mA}\$

We need to find the current amplification \$B\$.
My approach was to calculate \$U_C\$, the Voltage which drops at \$R_C\$. I read in a book that \$I_C\$ is the current we need to use Ohm's Law at \$R_C\$. So I solved the equation \$U_R = I_C \cdot R_C \Leftrightarrow U_R = 12\text{mA} \cdot 972 \Omega \Leftrightarrow U_R = 11.664\text{V}\$.

Having this done I was able to use the Mesh-Current-Law at the upper right part of the circuit which gave me the following equation \$-U_{CC} + U_C - U_B\$ where \$U_B\$ is the Voltage which drops at \$R_B\$. Filling the equation with the known values we receive \$U_B = 1.664\text{V}\$. Since we have \$R_B\$ given we can now apply Ohm's Law with the previously calculated Voltage which leads to the following value for

\$I_B = \frac {U_B}{R_B} = \frac {1.664\text{V}}{14000 \Omega} = 1.188571429x10^{-4}\text{ A}\$

or \$0.1188571429\text{ mA}\$.

Now I found out that the base current \$B\$ can be expressed by \$B = \frac {I_C}{I_B}\$.

Since we know \$I_C\$ as well as \$I_B\$ I went ahead and filled out the equation which gave me \$B = \frac {12\text{mA}}{0.1188571429\text{mA}} = 100.9615385\$ for \$B\$.

Am I on the right track?


texts: I have managed to control an RGB LED Strip with an Arduino Uno R3 successfully. I would now like to switch and dim 12v LED Down lights. I am unsure of how to do this the Transformers I have  are dimmable and have 10 watt dimmable LEDS. Would anyone be able to provide information on how to wire them while still being able to dim them manually. Also I have an assortment of electronics bits such as mosfets, transistors etc.


texts: Can an OpAmp be built without an IC or transistor or a Vacuum tube?

texts:
Is it possible to build an OpAmp without using an integrated circuit or a transistor or a vacuum tube?  I wanted to see how it would look on a larger scale before miniaturization on a chip.

I was hoping for a high view of what that would entail, not only that it is logically possible.

@HarrySvensson Thanks. That is what I wanted. I didn't mean to cause a ruckus. I only wanted to see what was going on outside of all the YouTube videos and all the rest. I figured if I could see it with big chunky non-IC parts, I could understand it. Apparently I miscalculated there.

What I should have asked for was an equivalent circuit.  Now I know the keywords to search and have found many.


texts: Cant get a grasp on how a full bridge on IR2104 works

texts:
I'm trying to build a full bridge DC motor driver on two IR2401 using an Arduino Motor Driver Shield as a reference.

It is recommended (if i understand right) to drive this kind of circuit as follows: put a HIGH at [!SD] to enable the circuit and PWM at [IN], where PWM duty cycle will set the duty cycle of upper or lower FET in a half-bridge.

Now when I try to combine it to form a full bridge - here comes trouble. If I understand right, there will be a moment in circuit's operation, when the opposite direction FETs will be toggled, so my motor will basically be braking a certain percentage of time.
The bridge is powered by booster circuit, so FETs don't need bootstrapping.
For example, if I want to turn the engine ON to 20% of power I will send a 20% PWM to the upper IR2104 and 80% PWM to the lower, this way it will open corresponding FETs (Q6 and Q7), but at the other PWM's half-period there will be Q5 and Q8 opened, effectively setting the motor to a counter-rotation mode. Is there any logic in this opearation mode for this circuit or I'm misleaded in some way?

Pic 1: Normal operation, simple logic LOW on the "B" side, PWM to control power on the "A" side.

EDIT: Added an explanation of my concern, added a note about the booster circuit

Pic 2: Motor winding short circuit when PWM goes to negative half-period.


texts: Is there any alternative device to replace OPA333? I can't find it in my simulation. Is there any DIP-8 chip layout so I can fix in my breadboard for testing? What should be the solution for linear or analog devices?


texts:
I am using CC2640 from TI in one of my designs. As per the datasheet, I can output a clock of maximum 32KHz to any external circuit/IC. As per my design, I Need to provide 1MHz clock to a sensor.

CC2640 has 4 32bit timers & all are PWM capable. So, my doubt is :-

Can I generate a 1MHz clock using timer in PWM mode?
How do I know what is the resolution of my timer if I am operating CC2640 on 24MHz.


texts: Is there a safe way to run a camera on a Lithium ion AND external power at the same time?

texts:
Similar, but not quite the same to this Question; "Charging and Using a Li-Po battery simultaneously", I want to have a battery in my camera but also connect an external charger at the same time.  Is there a safe way to do this please?

The application is to power my DSLR camera (Olympus OMD EM10) during an overnight timelapse shoot. The camera wakes up every minute and takes a picture. It can take 999 pictures, but the battery only lasts a few hundred..s

The battery is a Li-ion 7.2v 1210mAh unit.  This lasts a few hours but isn't enough to do a full night.  Because I'm using a tripod, I could have the battery compartment open and fit the battery on top of the terminals, capturing the leads of an external power supply. But I'm worried this might toast the battery or worse, destroy the camera!

(As an aside, the battery - BLS-50 - appears to have four contacts!)

If this is "dangerous" - it is certainly inconvenient away from the house! - , how could I bodge together multiple cells to safely add duration? [EDIT: SO, this isn't thought dangerous.  Moving on then, how could I power this from the mains and with a battery at the same time? And could a 5v 10AH USB power bank/battery pack be used or would the voltage difference be too much?]

(Surprisingly, Amazon let us all down and doesn't sell such things...)

Many thanks!

John


texts: Driving MFET with IO Expander ( mcp23008/mcp23017)

texts:
for my project I want to drive about 12 x IRLl014 FETs with an ESP32. To get more pins I want to put a IO-expander, either a MCP23017 or MC23008 onto the I2C and out onto the gate.
I know that driving the IRL directly works with an IO but what about the expander?
The maximum current can be 20mA per IO or 150mA total. So using the 16 channel would get me a really low current to charge the FET?
The FETs either drive SSRs or motors.

simulate this circuit – Schematic created using CircuitLab
I tried to make a simplified schematic. It works like this ESP32 > I2C/MCP23008 or MCP23017 > MOSFET (either IRLL014 or IRF3704). > SSR or Pumps directly I use exactly 12x IRL014 and 4x IRF3704 right now it's set up like this:
FET1-8 on MCP23008_1, FET9-12 on MCP23008_2, PFET1-4 on MCP23008_3
On the load side there is either 24V or 12V depending on the jumper/load (whatever it needs, as I have 12V pumps or 24V pumps). Other than pumps there are also DCAC SSR(RLY1 in the schematic) to switch.
I got some questions there:

Would that even work? I don't really know how much current the gate of the FET draws. If every FET draws more than the MCP could deliver for a long while it makes smoke. Would I need a resistor in series to MCP to reduce the maximum current drawn? (And protect from on-off switching currents?)
Would I notice the charging times with <20mA?
Do I need a level shifter if I power the MCP with 5V?

I know I could also just control them with 3v3 Volt but I read that more voltage makes the FET switch better. Is that correct?

Do I need to watch anything specific aswell if I set it up like that (something that I didn't thought of)?

Thanks!


texts: How to become an embedded software developer?

texts:
I'd like some tips for those who want to become a good embedded software developer or want to improve in this area.

What should I need learn about hardware, software?

Which books are most recommended? Blogs?

In the end, how could I go from a beginner hobbyist to an excellent professional?


texts: Is there a difference between SOIC and SOP?

texts:
I'm looking at two integrated circuit packages: SOIC and SOP. They seem (almost) identical (pitch, overall size, etc...)

SOP

SOIC

Is there any important differences between these two packages that I am overlooking?


texts:
The common 555 timer triggers the output when the trigger signal falls down. Although this is not a problem, I want it to do the opposite, which is to trigger when the signal that controls the 555 goes high. The circuit I am using is a typical monostable configuration with the following simulation result:

However, if I design a NOT gate using a BJT to achieve the needed behavior, it does not work properly:

Here is the voltage evolution at the trigger pin compared with the others:

Does anyone know why is this happening?


texts: 140 IR LEDs at 30 MHz using a frequency generator

texts:
I need to blink IR LEDs at different Hz and I am going to use a frequency generator for that. The frequency generator is 30 MHz and that is the maximum I need to blink the LEDs.
I was thinking to use a MOSFET for that so I have a big 12 V battery and flick the LEDs on and off using the MOSFET as a switch with the frequency generator as signal to the gate. I understand that a normal MOSFET would not handle 30 MHz and therefore I need advice. The schematic is listed.  It would work with lower frequency but not high.
The IR LEDs are going to draw 2 A.
Summary: I need something to act as a switch to switch power to the IR LEDs and a normal MOSFET would be good but not when blinking at the high frequencies.


texts: Soldering nickel wiring to nickel plated brass with electric arc

texts:
Oke, this is probably a simple question, although i cannot find it on the great internet.

I was in a factory that solders wires to a jack plug, as can be seen in this video from 2:20:
http://www.tudou.com/programs/view/YL5JebwX-Ac/

The soldering is different than my standard soldering iron at home which is always hot.
Where this iron only heats up at contact with some kind of spark or arc.

What is the name of this soldering technique?
What is the name of the soldering iron tool?


texts:
I am repairing an AVO multiminor Mk 4 which was in a sort circuit across a car battery while in the 1 amp measuring position. circuit diagram here

an obvious casualty was the 0.25 ohm resistance R1 which is implemented as a length of resistance wire of approx ( it has been cooked and burnt out ) 22SWG. The length of this wire was approx ( same excuses ) 10 inches overall

Now to my question:
if I want a 10 inch length of resistance wire to be 0.25 ohm ,  I am looking at a resistivity of 1 ohm / meter. But nichrome wire in 22SWG is 2.82 ohm/meter ( looking at about 7cm total length which would give me quite a fitting problem. Falling back to 18SWG gets the length back into the right ballpark (18swg => 0.924 ohm/meter)

but add to the above that nichrome is a beast to solder do I have any other choice of resistance wire commonly available and easily soldered ?


texts: How to calullate RMS current through switch (MOSFET) in boost converter?

texts:
Trying to calculate values for a boost converter based on document Basic Calculation of a Boost Converter's Power Stage.

Want to know power dissipation though MOSFET which that document does not mention.

It mentions maximum switching current:

$$
I_{SW(max)} = \frac{\Delta I_L}{2} + \frac{I_{OUT(max)}}{1-D}
$$

where:

\$\Delta I_L\$ - ripple current trough inductor
\$I_{OUT(max)}\$ - maximum output current
\$D\$ - duty cycle

How to calculate RMS switching current through MOSFET so power dissipation can be calculated?


texts: ESD Input protection on low Vmax digital inputs (3.6v)

texts:
I have a microcontroller monitoring a few digital inputs. The max voltage on these inputs is VCC + 0.3v. VCC is 3.6v so these inputs can't be higher than 3.9v. These digital input are just switch closures on a button, toggle, or any other various human operated switch. Input response time is definitely not critical. The switch will be connected to the uC via a length of cable. Cable length will vary based on customer's needs; anywhere from a few feet to 1,000 feet. This will be industrial application so lightning is the main concern.

I wanted to use capacitor --> series resistor --> TVS --> series resistor --> capacitor --> uC input. However, I understand TVS diodes will give fastest response, zeners will be too slow as I understand. The problem is, all TVS diodes that have a working voltage of 3.65-3.8v have a breakdown voltage and clamping voltage way too high. I see some breakdown ratings of 3.8, but clamping is upwards of 6-15v! I'm assuming my input will be fried before the VTS reaches full clamp.

With such low input Vmax, am I limited to zener/schottky diode protection?


texts: Is a protection diode needed for a resistive load?

texts: In some applications a flyback diode is added parallel to the load. Is that because the switching causes reverse voltage for inductive loads? What if we have a resistive load instead? Do we still need to take care of switching? In the below figure there is a read switch operating on an inductive load. Would we still need it if the load were nothing but a resistor?


texts: Why do I need I large resistor to the GATE of my MOSFET?

texts:
I tried to control the brightness of a LED using a Linear Hall Effect Sensor fed to an Arduino, and PWM output to the gate of a MOSFET connected to a 12V battery.

The LED was flickering a lot, and after some searching around, I found out that adding a 10k resistor  to ground before the gate of my MOSFET solved the problem. However, I havent found a good explanation as to why this fixes the problem. Does anyone have an explanetion?


texts: ESP32 touch sensor outputs unstable values

texts:
I am trying to implement touch functionality of esp32 development board to toggle a led. But on uploading a simple touch detection sketch, output have spikes i.e. usually value remains near 100 but falls to around 30 randomly for no reason. This triggers false touch. I have tried this with two esp32 dev boards I have and the problem persists in both. Also I have tried this with and without external wire from the touch pin.
Code I've used:-
void setup() {
  Serial.begin(115200);
}

void loop() {
  Serial.println(touchRead(27));
  delay(10);
}

Serial plotter output:-

Without external wire connected with touch pin

With external wire connected with touch pin

UPDATE:-
3. Actual touch represented by T1, T2, T3


texts: Convert from line level to mic level, without worsening the sound quality

texts:
I have an audio signal coming out from an iPhone  which I would like to record in iPad using its mic input.

I have tried this with simple resistor divider (and TRS-TRRS connectors), but it seems to worsen the sound quality.

How can I do this without worsening the sound quality ? Are there any off the shelf components I could use to achieve this ?

I came across this adaptor, but it says 50dB loss, I guess my sound quality would drop, which is not great for my application.


texts: Microcontroller Interfacing with Stepper Motor - Current Consumption

texts:
I have this MPC5606S Microcontroller which I have interfaced with this Sonceboz Bi polar Stepper Motor.
The Microcontroller is powered up by 5V and 3.3V and the Stepper motor interface is connected to the 5V Power domain.
I am a little new to this stepper motor working.
This is the connection between the Microcontroller and the stepper motor :

There is also another same stepper motor for the "SPEED" net but I am showing only for the Tacho net.
The input to the COS+, COS- pins of the Stepper are 15kHz, 50% duty cycle PWM Input and the rise time & fall time of the signals is in the order of 30ns-40ns
All I want to understand is the how to calculate - how much current does the motor consume during the normal condition? How to calculate the current consumption of this bipolar stepper motor which takes the current from the Microcontroller pins? I am trying to calculate the maximum output current of the Microcontroller through its output ports.


texts:
I am working on a small project that requires an Arduino (Yún?) to be powered by battery and connect to wifi. I am thinking of using the Yún since it already has wifi abilities.

My question is: What is the best way to power this in the long term (6 months min) indoors. I also need this to quite small. Would regular small batteries be my best bet? Could I hook up a phone battery or something like that?

Thanks