texts:
I need to amplify a signal which is oscillating between 3V and -3V at a frequency of +- 10MHz, into the 10-20kVolts range.

I've been looking for an opamp or a transistor but the max supply voltage I've found is 1.7kV

Anyone knows of an opamp/transistor meeting those requirements?
Or any other means to increase the voltage of a signal...

Thanks

Edit :
Following different answers, here are some more informations.
I'm trying to duplicate, with a few upgrades, a device that generate a wave at 1MHz, with an constant amplitude of 4kV. I've measured those data with my oscilloscope and a voltage divider quite easily.
Example of such device : https://en.m.wikipedia.org/wiki/Electrosurgery @ "Electrosurgical waveforms"

I would like to be able to generate a carrier wave from 1MHz to 10 MHz and modulate its amplitude at will. And a bit more voltage is always nice ;-)

In order to have complete freedom on the waveform, I believe it is easier to generate the voltage digitally and use a DAC to convert it. This is the reason of the initial signal being between -3V and +3V. (Or between 0V and 5V, or 0V and 3V, ... In the micro-controller range)

I need to be able to change the signal on the fly (some software lags are acceptable but not powering down and changing a couple of inductances to adjust the resonance frequency)

Concerning the power output, less then 100 W is perfect.

Again, thanks a lot for your time and your inputs !!!


texts: I'm designing a board with a micro that controls a hobby servo. The circuit is usually powered from 12VDC but may be disconnected at any point, thus we have 2 lithium cells in series providing ~7.4V that will run the servo(which pulls substantial current maybe ~2A) and a small LDO 5V regulator for the micro. What I'm looking for is a lithium charger IC that will charge and balance the two cells (ofc I can't charge the 2cells in series, which is dangerous, thus I need a balance circuit that is connected to each individual cell) while the external 12VDC is connected. Can anyone recommend anything? Can I run the circuit off the cells always and just use the 12V to charge the cells when connected?


texts: Is there a risk for the HW to debug an embedded software if the JTAG integrity is bad?

texts:
I had to debug a C embedded software in a noisy environment.
As a result the integrity test of the JTAG connection had a failing rate between 30% and 60%.

What are the risks to make JTAG accesses in such conditions?
I mean:

Could I burn the microcontroller?
Is it possible to corrupt the non volatile memory forever?
Do HW protection mechanism that protect the chip exists? (thus preventing any JTAG accesses [program update, debug session, etc.])
Is it possible that the data displayed by the debugger is wrong?

The target is a TI C2000. But I would prefer general answer if possible.


texts: Grounding a soldering iron and it's enclosure

texts:
So, I assembled a soldering iron kit and put the control unit in an aluminum enclosure and intend to use a  Mean Well SP-240 24V power supply with it. I just wanted to verify a couple of things. The tip should be connected to chassis ground via a  1MΩ resistor and chassis ground should be connected to the Mean Well's FG (mains earth), right? To be clear, power/signal ground are seperate from chassis ground in this system and it's only the latter I'm referring to.

[not sure if it matters but this is Sweden, mains 230V/50Hz, PSU is 24V 240W (~10A), soldering iron is 24V 70W (~3A)]


texts: What is the white wire for on this voltmeter?

texts:
I found this voltmeter on eBay, and I know what the red and black wires are for (live and ground respectively, or alternative names), but I have no idea what the white wire is for. As its top range is 99 volts it can't be high voltage.

The listing does not say what it is for, and it has a really complicated circuit diagram which I cannot understand at all.

Please could somebody tell me what this is for?


texts: How to simply introduce a short (2ns) delay on a line?

texts:
We found a race condition in one of our production circuits.

A CPLD chip acting as address decoder plus a couple other functions, receives address and data signal over two buses. A peripheral device has only one bus, and latches the value on the bus as address on falling edge of the ALE line, then as data on rising edge.

The CPLD outputs the contents of the address bus on high level of the ALE line, contents of the data bus on low ALE line.

simulate this circuit – Schematic created using CircuitLab

Data sheets say the peripheral needs both the address and data state to be sustained for 2ns after receiving the ALE edge to latch them properly. Unfortunately, in some cases the decoder is faster, leading to the peripheral latching the lines when they are transitioning from address to data or vice versa.

Introducing a 2ns delay on the line to the decoder (while not affecting the signal to the peripheral) would resolve the issue.

The CPLD is filled to the brim so adding extra logic to it won't work, and since it's a part of a device already deployed, reworking everything is out of question (stuff like adding separate 'toggle' line from the CPU, driven separately from ALE) - we need a "hot fix", something small, simple and easy to add. So my question - how to easily introduce a delay of order of 2ns to a line like that? (specifically, not delaying it on the second branch, so that that the peripheral receives the signal 2ns before the decoder does.)


texts: Should I switch 120 AC or 24 DC with a relay?

texts:
I would like to use a relay to switch power to an LED grow light. The grow light comes with an AC/DC adapter that takes mains US power and converts it to 24 VDC 1.8 A. Should I put a relay before the adapter or after the adapter? At work, we only use 12 and 24 VDC automotive relays so I've never actually had to pick.

Edit: I haven't picked the relay yet.


texts: VU meter noises entering the master output

texts: I'm currently working on a very simple mixing table, and everything works fine except that when I connect the VU meter (using a Y splitter from the master output, one end going to the audio output jack and the other to the VU meter), it produces a high pitched noise that gets into the master output. How could I fix that?


texts:
Its important to mention that I'm noob. I bought 500mw 405nm TTL module laser(5-12 volt) driver circuit. When I supplied laser with 12 volt, it turns on with max power. but when i connects laser TTL module to arduino (pin 11) in order to control turning on & off of laser through GRBL(CNC machine language) command with full power, the output of laser reduces.

"M05 S0" turns off the laser while "M03 S255" should turns on the laser with full power as it is turning on with direct 12 volt supply, but its not happening.

so how can I make laser turn on with full power with arduino control?

Laser I,m using https://www.amazon.in/gp/product/B071J2W7V8/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

Laser driver circuit


texts: Microcontrollers/microprocessors and different bit versions, what's the difference?

texts:
As a general engineering hobbyist, I am learning more about the world of microcontrollers each and every day. Once thing I don't quite understand though is the significance of the bit version of a microcontroller.

I have been using the ATmega8 for several months, and it seems to work great for my purposes. I know how things like clock speed, memory, number of IO pins, types of communications buses, etc. differentiate one micrcontroller from another. But I don't quite understand the significance of, say, 8-bit vs. 16-bit vs. 32-bit. I do understand that a higher bit version allows the device to store larger numbers, but again, how does this impact my decision? If I am designing a product, under which hypothetical scenario would I decide that an 8-bit processor simply won't do, and that I need something higher.

Is there any reason to believe that a theoretical 32-bit variant of the ATmega8 (all other things equal) would be superior to an 8-bit version (if such a device was possible)?

I may be speaking nonsense, but I guess that's a result of my confusion.


texts: Parallel Power Supplies with Ideal Diodes

texts:
I'm working on a project that operates at 5v - and can draw UP to 10 amps.  Under normal conditions, it won't be doing that - probably closer to 3 amps, and (if configured for low-power) only 450mA or so.

It's designed to be powered from USB when in low-power mode, but I also want to have 2 barrel jack to add external power supplies (5V, 8A from aliexpress).  Obviously I don't want the power supply backfeeding the USB, or the USB backfeeding the power supply.  I want the option to plug in two of these power supplies because most of the time, I won't need to activate the 10A mode - so just one power supply would be sufficient.

Considering these power supplies are not designed to be paralleled (no master/slave setup, etc), how effective would an ideal diode be in enabling these various sources to all operate in parallel (to increase max current)?

Note that I don't need the load sharing to be perfect, but I'd like to avoid serious issues.  I originally thought I could just use a P-Channel MOSFET, but after some research have learned that when they are "on" they allow current to flow both ways, which makes them non-ideal non-diodes (less than helpful).


texts:
I have a dc motor that comes from a 18V corless drill. I made a small waterpump that will pump maybe 10minutes at a time 5times a day maybe 20 days a year.
I use the motor to drive the pump. The problem is it has a very thin shaft and becuase it starts at full speed immidiately when it starts, it breaks may attachement to the waterpump. It draws 1.12 amps at full speed,I use a 12v battery to drive it. Is there a simple electronic circuit I can build to cause it to get to full speed in maybe .5 seconds or 1second instead of immidiate full speed? So that there is not so much force on my attachment mechanism?
It does not have to be variable, just soften the initial start every time.


texts:
I am very new to using Eagle CAD. One thing that I am trying to do is use a schematic that is not in a library as a part in my main schematic. I'm not able to find anything that allows me to do that. Whenever I use the "Open" option in the "file", it just closes my main schematic and opens the schematic that I selected. How should I go about accomplishing this?
Thanks.


texts: Distortion due to transmission line effects of low pass filtering?

texts:
I’m currently working on a circuit set up where I’m using high speed serial to send data. However, I took a closer look at the clock signal and it appears to be distorted. I’m trying to determine potential sources of distortion. I’ve narrowed it down to three things: there is an impedance mismatch on the transmission line, the cable is somehow low pass filtering the signal, or the device is simply producing a bad clock signal.

I’ve done some investigation into determining whether or not it’s a transmission line related issue. My setup: A device sourcing the clock signal at 12.5 Mhz with an unknown output impedance. I’m currently waiting to hear back from the manufacturer to determine this output impedance. This signal is then placed on a 10 ft cable (non-coaxial cable - http://multimedia.3m.com/mws/media/343873O/3mtm-shrunk-delta-ribbon-sdr-cable-assembly-ts2120.pdf). It states that the characeteristic impedance of this cable is 100 ohms. The signal is then going into a high speed data acquisition device with input impedance of 50K ohms.

I’ve attempted to impedance match the source, transmission line, and input data acquisition all to 100 ohms. I placed a 100 ohm resistor across the input data acquisition terminals, but I have not done anything related to the clock generating device since I don’t know the output impedance. I have a couple picture of the clock signal running at 6.25 MHz and you can see the distortion.

Does this distortion appear to be due to the effects of transmission lines? Or does it look like it is more just due to low pass filtering? However, there are some jagged steps in the signal which don’t seem characteristic of simple low pass filtering of a clock signal.

And I suppose it could also be due a badly generated clock signal to begin with.

Any ideas?


texts:
I am trying to design an ultra low noise power supply for my sensitive circuit. The supply will provide 5V and 600mA. (Worst case, 200mA typical). My input voltage is 2V to 4V. My ripple target under load is less than 5mV.

The signals I am trying to measure are very small, nA level, and the opamps need to be on a very clean supply hence the very low noise DC/DC converter requirement.

What are the precautions I can take and what are the parameters I should look at while I am selecting the DC/DC converter. I know the forum doesn't like people to provide specific requirements but in this case I appreciate if you could indicate parts that meets the parameters indicated.

Also, what other circuit level precautions I can take? Decoupling caps for once but are there others?

UPDATE
My source is a simple two AA batteries, alkaline, but people may use other stuff. Anything that fits to AA battery compartment.

My signal, the opamp input, is 1Mhz with 75% duty cycle

UPDATE 2
I went back and completely re-look at the design, change the Opamps so that I can turn off the power to them (and they can work at 4.5V), arranged GPIOs etc so that we can control the power flow, changed some of the modulation schemes etc. At last, I was able to bring down the total requirement of power to 400mA where 200mA for 5V and 200mA for 3.3V.

I have chosen the high efficiency TI part for the design on the switcher side. TPS661100. This has an LDO which I will use for 3.3V. (interestingly, this LDO has a great PSRR but I am afraid to use it for the 5V supply since I cannot pass it through a pi network before feeding into the LDO) Now I am trying to choose an external LDO to for 5V. This switcher has 500Khz switching frequency but finding an LDO that has a good rejection at 500Khz proved to be challenging. I can find parts that has a low drop out and 30dB PSRR but nothing like you guys recommended such as 60-70dB. I am now open to suggestions and feedback.

Final note, when my design is complete, I will extend this question so that the next guy can follow or learn from my experience. Thanks to you all.


texts:
I've read that Sziklai is prone to high frequency oscillations due to its feedback loop.
I can't figure out where this feedback loop actually is.
It should be obvious but I haven't understood this concept.


texts: Driving 3 Mosfets with a MSP430FR4133 from 0% to 100% Duty Cycle

texts:
I'm having an issue with a Mosfet driver that I put together. It is a MSP430FR4133 taking in 3 square wave signals and outputting them at a higher frequency. The new signal is put through 3 separate Mosfet drivers to drive LEDs. The problem I'm having is, when I dim the LEDs the Mosfets output the wrong signal at the 2% - 19% Duty cycle Range. 1% works fine and 20 - 100% work fine. I'm sure that I'm just missing some supporting components but I'm really unsure what I'm missing.

simulate this circuit – Schematic created using CircuitLab

Sorry if the schematic is rough, this is my first time using that software.
Here is the signal after the MCU

Here is my issue, after the MOSFET

Edit - I added a Pull up resistor on the drain and it made the waveform more stable. It now inverts the output of the MOSFET in between 2% and 19% Duty Cycle. I updated the issue picture with the new waveform. It is literally inverted from what its suppose to be.

Edit 2 - A symptom of the problem has been found. The Drain voltage is linear when its functioning properly. It is nearly the full 12 volts when we are at a 1% duty cycle and at 20% duty cycle we are at 10 volts. Going up from there the voltage drops properly. In the Problem area of 2% to 19 % duty cycle the voltage starts at 3.3 volts at 19% then around 16 % raises to 5.6 volts then drops down to 1 volt at 2 %. I originally was using a Launch-Pad for the processing of this application but I have now mounted the processor onto the PCB and I'm getting the same issue. The ground that's connected to the MOSFET is the same ground that is runs through the entire PCB. I'm not sure if a ground issue would cause this problem considering the problem is so repeatable. Another Observation is that the problem is eliminated when I drop my frequency down to 600 hz which is the frequency of the input signal coming into my MCU. The higher the frequency the greater the issue.

Edit 3 - After doing some more research I believe that this issue is called Capacitive False Turn-on. Does anyone have advice as to how to fix this? The traces on my board are really thin because its a prototype board, is there something that I can add in order to fix this issue without getting a new prototype board? I have tried lowering the resistance of the Rg to 10 Ohms and it made the issue happen at 10% duty cycle instead of 20% and 1% is now messed up. It shrunk the problem area but hasnt solved it. When I raise the resistance, the issue gets worse.


texts:
I need to pulse a current through a coil, to create relatively short magnetic pulses.

I would like to know if I can use a function generator as the source of the pulses  and amplify the current that it produces, to the level I need or if an alternative method is necessary. I prefer to use the function generator as I can easily create and control arbitrary functions for the signal and vary my tests.

For the coil design I am looking at, it appears I need approximately 40 A of current for the field I am after, with the coil design I have.
Measuring the current from the function generator it appears to be approximately 180 mA when the amplitude of the voltage is set to 10 V. So the current gain would need to be ~220.

I have recently been learning about transistors and how they are used for current amplifier circuits. Would something like a MOSFET be suitable for what I would like to do?

Additionally as the coil is naturally an inductor, my understanding is the rise time is affected by the magnitude of the voltage driving the current. Larger voltages are required for shorter rise times. The calculated self inductance of my coil is 1.96 uH, so for the change in current from 0 - 40 A were needed to occur over a time period of 1us that would require ~ 80 V to drive it. Is this another factor I need to consider for the control of the pulse, or would a correctly implemented current amplifier circuit adjust for this? And if the pulses are even shorter this would require much higher voltages, what would be some things I would need to be cautious off?

The length of the period of the pulses is not as important to me as the rise time. There is a delay of several useconds between what I hope to observe and the rise or fall of the pulse, so the pulse widths should be longer than this, 5 - 10 us or longer would be suitable.

Any advice about the setup, alternative setups and where I may have gone wrong with my thinking would be appreciated.


texts: The transient response of parallel RLC circuit

texts:
I have simulated a transient and steady state response of below circuit. For the transient response the frequency is lower than the steady state. Is there any physics behind this? I was wondering if one could determine the transient and steady state of this circuit only by inspection and not by plotting the output response?

simulate this circuit – Schematic created using CircuitLab


texts: What does this op amp/transistor circuit do? (revised circuit)

texts:
simulate this circuit – Schematic created using CircuitLab

I asked a question yesterday about the circuit above, but my notes showed the op amp terminals mistakenly swapped and the circuit in my original question displayed positive feedback.

After studying it some time, I understand why the circuit no longer displays positive feedback but it's still not clear to me what this circuit does.

It's clear the voltage divider sets the voltage on the - terminal of the op amp to a value between 9V and 10V, but I don't understand how the rest of the circuit responds. In particular, it's not clear to me how the transistor affects the feedback loop and how the second power supply input affects the differential voltage at the op amp inputs.

I'm particularly interested in understanding how much voltage and current the circuit supplies to the load. I'm also interested in how real (ie. non-perfect) op amps might behave differently and the tradeoffs involved in picking the right op amp for this circuit.

Thank you. I'm a beginner and overall very confused by op amps and transistors.


texts:
I have always been told that for a sinusoidal variable (for instance a voltage signal), the fourier transform coincides with the phasor definition, and this is the reason why the analysis of sinusoidal circuits is done through the phasor method.
But I do not find this correspondence from a mathematical point of view.
Consider for instance this signal and this phasor definition:

If now we calculate its Fourier transform by using its properties, we get:

If we evaluate this one at the pulsation 5, it seems to me different from the phasor (especially because of the presence of the dirac pulse).


texts:
I'm trying to receive CAN messages from a radar, whose specification define the following data for bit timing:

CAN baudrate = 250 kBaud
Tseg1 = 8
Tseg2 = 7
Tsjw  = 4
Synchronization on one edge only.

I'm using a 16 MHz crystal in the classic MCP2515 (CAN Controller) + MCP2551 (CAN Transceiver) setup, which I use between the CAN bus and an Arduino Uno, but I believe I'm having some trouble when setting the bit timing configuration in the MCP2515.

This is because using a 16 MHz clock frequency limits the Time Quanta per bit time to be 16. I'm using the MBtime tool to verify the bit timing.

     1 time quanta synchronization segment
   + 1 time quanta propagation delay
   + 8 time quanta phase segment 1
   + 7 time quanta phase segment 2
 ----------------------------
  = 17 time quanta

Which is one more than the required one (16). Being the sync segment is always one, and the propagation segment at least one, how is it possible to make it work with the required parameters?

My ideas are using another crystal, maybe 18 or 20 MHz. (I actually tried with 20 MHz and a four time quanta propagation delay, and it didn't work.)

However, using a CAN-to-USB converter in my PC, I did successfully receive the CAN frames I was expecting from the radar. I set the same settings (Tseg1, Tseg2, SJW, and baud rate). And this converter uses a 16 MHz crystal...

Is there something I'm missing? Should I change the oscillator frequency to another value?


texts: How many clock cycles does reading digital input on an AVR microcontrollers take?

texts: How many clock cycles does it take to read digital inputs in avr microcontrollers? For example, how many clock cycles would SomePreDeclaredByte = PINB; take?


texts: I plan to make a circuit for a system and most of parts in the system use this type of connector. What is it called? (in the picture it is 10 pins while there are also 14 pins in the system)


texts:
Does the diode ideality factor can be lesser than 1? or very close to 1?

ID and VD are the diode current and voltage, respectively

q is the charge on the electron

n is the ideality factor

k is Boltzmann’s  constant

T is temperature in Kelvin


texts: Why do some LCD manufacturers use linear polarizer and some others don't?

texts:
I wanted to buy some pieces of linear polarizing films for experiments with polarized LED lights. I could not find any options in local shops nor in Europe Amazon, but some quick search told me that LCD polarizers are usually linear, vertical, horizontal, 45 or 135 degrees. I definitely knew that I don't need circular polarizers but from most materials I found online, it seems that all LCD panels should have linear polarizers because that is crucial part of LCD inner workings. So I found and ordered some Samsung Note and Galaxy LCD polarizers from AliExpress sellers with high reputation and positive reviews.

When I received the polarizers, I was surprised. They do not work as polarizers at all! They pass the light through, no matter how I cross them and even when I look through them at my LCD monitor or at a smartphone screen. When I look at daylight through one of those polarizers, they seem to be just like tinted film. But when two of them are combined or when looking through them at any LCD screen, a strong rainbowing effect appears. So, definitely they are not just a tinted film; they do interact with light in some way.

In comparison, my linearly polarized sunglasses work as expected, blocking almost all the light when I look through them at my LCD monitor (Viewsonic VP2365WB) and my Sansa Clip MP3 player and the light starts coming through if I rotate my head. But the sunglasses do not work as polarizers with my smartphone (HTC One M8S) - I can see the screen no matter how I rotate my head. Thus I deduced that my smartphone does not have linear polarizer, and also that the polarizers I bought are not linear.

So, they might be circular polarizers but I'm not sure because searching for circular polarizers on the Internet gives me results about photography circular polarizers which seem to work somewhat differently to the ones I have.

How can LCD pixels on my smartphone show up if the LC panel is not put behind a linear polarizer? How else does it work and why the polarizers are needed at all?


texts: Burnt SMD diode identification. General Semiconductor S4 6CA

texts: I have an Artesyn 7001138-Y000 835 server power supply unit that has a burnt component. The burnt component reads S4 6CA and has the general Semiconductor logo on it. I have been looking online to find the specifications so I can replace it, but I have been unsuccessful. If anyone can help me out so I can get this running again that would be awesome!


texts: Why does this simple FET circuit behave this way?

texts:
In the circuit above, when S1 is pressed and released, the LED turns ON and stays ON.  Why is this so?  I can't directly measure the Gate Voltage with a DMM since connecting the DMM results in the LED not staying ON.

If the LED is ON (S1 pressed then released), when S2 is pressed and released, the LED turns OFF, as expected.

I skimmed my intro ECE book chapter on FETs and it didn't seem to mention anything about this phenomenon...


texts: Why is the current mirrors output unequal?

texts:
I made a LTspice simulation of a pmos current mirror. The current source should model a photodiode (without parasitic capacity). The W/L ratio is the same for both Mosfets. I expected the plot of the output current (red) to be the same as the input current (blue). I thought it will rise in a linear manner as the input current (the sweep is linear).
Now I see that the output current is logarithmic (see plot: red curve).
Can someone explain this difference?


texts:
Is it possible to charge 3x NiMH AA (eneloops) in series with a TP4056 module?

I know that TP4056 will automatically cut off charging when Li-ion reaches 4.2v.

So 3x 1.2v Ni-MH = 3.6v, TP4056 starts charging.
When NiMH reaches 1.4v then it will be 4.2v in series and TP4056 shall stop?

btw my TP4056 module is modified to charge at 200mA rate instead of the default 1A rate.


texts: Distance an inverted F antenna should be from the bottom and side edges of a PCB?

texts:
Distance from the bottom is usually either in the center of the PCB or close to the bottom edge with the length arm always pointing toward the farthest edge from the antenna position.
CENTER?

OR EDGE?

This information says the best location is at the side of the board, you can see the darkened lines in the image which indicate the side edges of the ground plane I assume.

This image is for an ESP32 module, it recommends the positions with a green check mark (which are located near the edge) and the length of arm of the MIFA must always be pointed down towards the farthest edge. (datasheet page 17)

But in this video of an antenna generated by the HFSS Antenna Toolkit, it is positioned in the center of the board, and HFSS is some pretty heavy-duty software so I imagine it should have a lot of credibility.

Also, is there an ideal distance the antenna should be from the side edge? Should it have perhaps at least the width of the antenna trace width away from the edge, or more? Or should it be as close to the edge as possible, maybe it would radiate better that way?


texts: oscilloscope turning off during pulsed power tests

texts:
I'm recording voltage and current waveforms using an oscilloscope. The application is pulsed power.

A problem I am having is the oscilloscope is losing power / turning off when I trigger the system. The oscilloscope is connected to voltage and current probes via coaxial cables. Power is provided to the oscilloscope by a battery-powered-UPS (which is disconnected from mains power during tests).

The oscilloscope can lose power immediately after triggering the system, or a few seconds later. Sometimes it seems to work just fine and I can record the desired waveforms. When the oscilloscope does lose power, it happens both when I measure voltage and current together, and when I measure them individually. When the probes are disconnected and the coaxial cable is lying on the floor, it also picks up a signal.

I think the oscilloscope is being turned off because the signal along the coaxial cables is too strong. I don't want this happen, and am concerned I'm damaging the oscilloscope.

What are some things I can do / need to consider to stop this happening? Even generally, what would cause an oscilloscope to lose power like this, and how would that be rectified?

My background is not electrical engineering so I am a bit lost. Appropriate search terms for me to use would also be helpful, so I can try to do some more self-research.


texts: Cheapest way to synchronise date and time for standalone system?

texts:
If you have a device connected to a network, the answer is obvious - use NTP.

If you don't have a network connection, I can think of 3 ways to get the current date and time:

Radio signal, i.e. WWV or WWVH in the US.
GPS.
Cell phone signal.

I don't know any of the pros and cons of each method, i.e. the availability and cost of chipsets or if you need a cell phone subscription to eavesdrop on a cell tower transmission.


texts: Does Nyquist rate depend on the sampling rate?

texts:
The book Computer Networks by Andrew S Tanenbaum mentions the following (paraphrased):

  For a noiseless channel, Nyquist theorem states:
    Maximum data rate = \$2H \space log_{2} V \$ bits/sec

    \$H\$ : channel bandwidth, \$V\$:  no. of discrete levels in the signal

In the end of chapter exercises, there's a question:

  A noiseless 4-kHz channel is sampled every 1 msec. What is the maximum data rate?

From what I understood, the maximum data rate is twice of the channel bandwidth for a two-level (binary) signal, which in this case is 8 kHz. However, I am unable to understand how the sampling rate comes into picture.

I think the sampling rate somehow influences the \$V\$ in the formula. Since we have 1000 samples/sec correspond to 8000 bits/sec (as per formula), this gives \$V\$ = 2, but I am not sure if this is correct, or even if it is required.

Could someone please explain this to me?


texts: An Adjustable Power Supply with Tracking

texts:
I like to built one lab power supply with Adjustable voltage and current control, so i found some cirtuit like this:

So i like t know how much power its need?

Is better (price and voltage quality) touse some  the ac/dc switching power supply or trnasformer by power doide bridge like this?

what do you sugest to combine  above kind system  to work toghter to give more current ( parrrlel ) and more voltage ( series) like traking systme exist in comersial power suppower, similar to this?:

Tganks.


texts: Will using a microSD card reader with STM32 produce logical errors?

texts:
I have a microSD card reader which needs \$5\,\mathrm{V}\$ to operate.
I am interfacing it with STM32 MCU operating at \$3.3\,\mathrm{V}\$.

Will it operate normally when I provide only \$3.3\,\mathrm{V}\$?

Presently, I do not have \$5\,\mathrm{V}\$ to supply to the card reader but only \$3.3\,\mathrm{V}\$.

Datasheet link is here.


texts: Resistance for water heating using 10 W solar panel

texts:
I am trying to do an experiment and see if I can use PV panel heating for a water tank. The problem is the PV panel is only 10 W. What would be the maximum resistance that I can attach to it to see some changes in water temperature, and what kind of resistance?

I was thinking of an aquarium resistance but I don't know if I can find something rated under 10 W.

Parameters of my panel are:

Pmax: 10 W; Maximum Power Current: 0.57 A; Maximum Power Voltage: 17.49 V; Short Circuit Current: 0.61 A; Open Circuit Voltage: 21.67 V; Maximum System Voltage: 1000 V.


texts: How to make 2 bit or more half adder circuit

texts:
I have no idea about electronics, this semester school gave us a strange and confusing lecture about circuits which we shouldn't take because we are no engineer or something close. Question is we should make an 8-bits fulladder and half adder logic circuit on Logisim. Everything is fine until i am stuck with half adder circuit.
I have successfully drawn 8 bit full adder

I have solved the puzzle which is connecting first Cout with second Cin. But in half adder there is only Cout. I don't know how to connect them each other.


texts: Impedance matching photon detector with multiple TTL counting devices

texts:
For my scientific work I wish to register signals coming from a photon detector which generates 50 Ohm TTL signals:

The expected count rate will never exceed 4 MHz.

The devices that need to record these signals are an NI-6343 of which the input impedance is orders of magnitude higher than 50 Ohm and a specialized time tagging device with 50 Ohm impedance on its input.

The time tagging device (TCSPC) and the detector are designed to be used together so there is no issue there. However, for reasons not relevant here, I also need the NI device to register the TTLs.

Everything is connected using Mil spec RG58 coaxial cable and I use a good quality 50 Ohm splitter to run the TTLs towards the NI device and my TCSPC.

Naively connecting things won't work: obviously the input impedance of the NI device is such that no current will flow to it and it 'sees' nothing as long as the 50 Ohm TCSPC is also connected on the other terminal of the splitter.

To address this I think I will use an OPA 2350 of which we happen to have a few in the lab. This opamp is 38 MHz so it might work just fine.

I think I need a unity gain buffer:

simulate this circuit – Schematic created using CircuitLab

However, since my knowledge of electronics doesn't go much further than Ohm's law I am not sure I am not missing something obvious:

Will the fact that the output impedance of the opamp is never really 0 mess with the voltage that is 'seen' by the NI-6343 as it is effectively in series with the NI-6343? Should I be wary of any other voltage division effects that might occur, effectively lowering the voltage of the output below TTL spec?
I do not have a -5V supply voltage in the NI-6343, only +5V. Therefore, I would ideally put the supply of the opamp between 0 and +5 but people tell me a 'symmetrical' supply might be better.

Any feedback would be much appreciated!


texts: An On/Off switch that can be controlled by an Arduino

texts:
I am a complete newb in electronic, so excuse me if I'm asking something completely basic, but here's the problem -
I have an Arduino UNO board, a battery and a motor. The arduino itself can't power the motor, not enough current, so I need to power the motor from the battery.

Obviously, if I just connect the motor and the battery together, then the motor will be on all the time. The solution is simple - put an on/off switch on the anode so that you can turn it on and off when needed.
But is there some kind of an.. electrical switch? That can be turned on/off by applying a 5v voltage to it, instead of mechanically clicking? I think transistors do something like this, but they seem to serve a huge amount of general purposes and I can't find any concrete information on how to use them for that purpose.


texts: I am trying to simulate BLDC drive using FOC with svPWM. The drive works very well in the continous operating regions, however i also want to include current and speed limits on the simulation. I have the datasheet of the motor stating the peak current and max speed of the motor, but how can i implement these limits in the drive model?


texts: Difference between L14-30 and L10-30 NEMA connectors?

texts:
What is the difference between a NEMA L14-30 plug (L14 type, 30 amps) and L10-30 plug (L10 type, 30 amps), electrically? With L10-30, one wire becomes neutral while the other one is hot and they change roles every half-cycle, so why does the L14-30 have a separate neutral?

I was looking for a converter for powering a dryer with a L10-30, but could not find that kind of device. I also want to know if it's possible to power other split-phase appliances in my house with an L14-30 plug on a generator.

Full reference for NEMA plug types is here (PDF).


texts: Sequential circuit: What does state mean exactly?

texts:
I have read some posts like:
What is state in a sequential circuit? about explaining what a state is in the sequential logic circuit. But the responses are pretty much the same as those ones in my textbook and I still don't understand what it is exactly.

From my understanding so far, I think a state is pretty much like the mode of a circuit when some certain inputs are given. For example, if we have a two-inputs SR latch, when S and R are 1 and 0, SR latch is in the set state, which I think it's like the circuit is in the setting/saving mode. (not sure if this understanding is correct or not)

But if this understanding is correct, I found out it is so weird to read my textbook. (Digital Design and Computer Architecture, second edition, David Money Harris)

"The chapter begins by studying latches and flip-flops, which are simple sequential circuits that store one bit of state." If state is similar to the concept of mode, why we can tell how many bits are there in a state?

Can someone please give me an accurate definition about the state? If it is possible to provide an analogy I will be really grateful, this would really help me understand this stuff.


texts: I want to turn on-off 5 big machines within 2 KM radius by Arduino. Will a GSM module work for me, or any better idea?

texts:
My farm have 5 big loads in 2 km radius which i want to turn on or off by Arduino (each load had MCU+GSM).

I have wifi ap in whole farm but it has 5 GHz channel only so drop idea to control it by arduino and ESP8266.

Does anybody have better idea except a GSM module?

If GSM is the only way then is it OK to use SIM900?


texts: How to create an array 1D X 1D X 1D with size 2X4X8 of type sfixed, STD_logic_vector, STD_LOGIC

texts: Is it possibe to create an array of type sfixed or std_logic?


texts: What kind of component would suit my needs?

texts:
I want to apologize first as I'm a beginer in electronics and my question might sound stupid.

I've started experiencing with my Arduino Uno (I love it!) and I wanted to start a project. However, I'm missing a key component and I'm not sure it even exists.

Basically, I want to create a sort of Knob that would be robotized. I want to be able to move it to a specific position (exactly like a Servo motor) but be able to manually turn the knob and that my arduino sense the difference.

I had some ideas, for example using a potentiometer with a step motor, but I'm not certain it's the best idea. I tried a regular Servo motor but I don't think they are meant to be "manually overriden" as it's really hard to do and there is no way to read the new position. Ideally, the solution has to be really precise and inexpensive.

Any suggestion would be greatly appreciated!
Thank you in advance and hurray for an Electronics stack exchange site! :D


texts: Blocking DC when driving a buzzer with a PWM signal

texts:
I am driving a piezo buzzer with a PWM signal (typical freq. 100Hz-1kHz) in order to generate 'beeps'. However due to software constrains (*), when the PWM signal is stopped I can't control if it stays at a high or a low level.

If it stays at a high level when stopped, then the power consumption of the buzzer increases, and it also generates more heat. I believe this could be solved if I could somehow block the DC component of the PWM signal that goes to the buzzer. Can anyone point at a sample circuit or application note on how to do this?

(*) Update: There is a (software) device driver which is not my own that turns the PWM signal on and off; when turning off, the PWM output stays at whatever level it was at that point.


texts:
A microphone jammer is a device that broadcasts ultrasound waves and, due to the non-linearity of mic amplifiers in small gadgets (i.e. smartphones) it overwhelms the microphone so the only sound the mic hears is hissing/beeping.
On the internet there is surprisingly not much about these devices. There is however this link and the github schematic is this one:
So, I am a relative noob with electronics but the questions are:

Does the 555 here generate just a wave or some other noise?
What are scope and scopeground pins?
What is this transformer for and can I modify the circuit not to use a transformer, as I can't find the model?
Can I use the UST40T ultrasonic speaker on this schematic?
What else do I need to modify to make it work?
Can one or two more speakers be attached or will I need a more powerful amp?
If I need to modify something, assume I can supply it with 5V, 9V and 12V.
P.S. Are these ultrasonic speakers easily broken/blown/damaged?
Thanks in advance.


texts: Why are home appliances and other devices made to operate on dc?

texts: Why are home appliances not designed to work on ac?why cant we just stepdown the incoming 230V and design the systems to operate at low ac voltages,instead of converting ac to dc?


texts: Touch screen reacts exclusively skin and stylus, how?

texts: I noticed that with my Android phone, the only things that it will respond to when tapped by are my skin and a stylus. It won't respond to taps by anything else. Not a toothbrush, not my hair, not a rough blanket, nothing other than my skin and a stylus. Why is this? Why does it not respond to taps from objects other than my skin and a stylus? Is there something about the microscopic properties of a stylus and my skin that makes it only respond to those taps? Why does it only respond to these 2 and nothing else?


texts: UC3845 flyback add a OVP (OVC) protection

texts:
I built SMPS based on this schematic:

It's working nicely - I recalculated transformer and flyback to 24V, I used EI33 transformer with airgap (put 6 pieces of paper between halves of the core). I can draw continuous power (100 W) as designed. Till now good.
Transformer details:
EI33 core from old atx PSU, primary inductance 1,5mH. Air gap is around 0,5-0,6mm. I calculated everything with Flyback 6000 software.

Problem is, when I connect resistive load to it (12 ohm -> I=24/12=2 A) and start to decrease it to (6 ohm I=24/6=4 A) - it works, but when increased further - voltage starts to drop. When loaded more (2 ohm or less ) it goes into hiccup mode. Circuit is designed to deliver 100 W, and it does, but when it is overloaded voltage drops, and when it's overloaded more - it does hiccup.
I don't like fact that voltage drops - it will lead to misbehavior of other powered circuitry. I would like it to go into hiccup mode just when I pass let's say 4.2 A.
Why this is so important?
I use this to drive motors, and when supply is overloaded it should stop them (driver for motors) but voltage drops to ~15 V and driver has no enough power. Also hiccup protects against overheating of diode/MOSFET.
How to implement it without compicating this ciruit too much?
What I tried so far:
Adjusted auxiliary turns to make go to hiccup faster (UC3845 goes into hiccup when supply voltage is too low). I was able to lower hiccup threshold, but no much. However circuit had problem with startup - several "clicks" are very bad to my ear :)
I thought about some sort of current sensing at the output.
Schematic from here: LINK


texts: Temperature calibration for of the shelf sensor nodes

texts:
Terminology:

sensor node
sensor

I have been experimenting with of the shelf temperature sensor nodes. The exact device in question is an Aeon Labs LLC, Aeontec Z-Wave MultiSensor 6.

I got the information that to reach the accuracy defined in the specs (+-1 Celsius) the sensor nodes have to be recalibrated after installation. The recalibration is done by using an offset value to even the sensor node temperature reading with a referent temperature reading.

I can reason the calibration of analog sensors where the voltage levels of the power can't be known at production time hence additional calibration is required once the power source is available.

This is an of the shelf sensor node intended to be used as a consumer electronic product. I haven't yet witnessed cheap dedicated thermometers ever needing calibration.

Questions:

Under what circumstances does a temperature sensor need calibration? (given that there are so many sensor nodes that don't offer the calibration mechanism)
Is the precision of +-1 Celsius a difficult requirement to achieve and can be severely reduced (3 Celsius difference between nodes placed next to each other) just by the fact that the sensor has been moved to a different environment (example. from loft to basement)?


texts: What is the (most likely) technical reason behind temperature specifications?

texts:
Im talking about electronic devices, which may be handheld or similar, so nothing exposed to "artificial" temperature (welding, soldering, cooling with liquid gas). Devices designed to be operated by ("unprotected") humans, indoors or outdoors, such is the temperature range.

My question is: What are the especially temperature sensitive parts? I guess Im interested in the lower end (0°C and below). Are the batteries sensitive? What is also likey to fail when it gets too cold? - Which in turn also mean: which part must be kept warm if one has to attempt to operate such device in too cold a enviroment?

Example: I have recently bought a laser distance meassure, a UNI-T UT391A+. The specified operating temperature range: 0°C to 40°C. Many similar devices (even the UT391A, without +) specify -10°C or lower as their lowest. Why is that? The most obvious difference between UT391A+ and others is that the former has integrated bubble levels. Could that be what bumps the temperature tolerance by 10°?


texts:
I've created a power converter based on an LM5085 IC. The converter was designed so that it can work with 24V in the input. Here is my schematic.

Requirements:
VIN - 24V
Vout - 3.3V
Imax = 1A
Imin = 0.1A
Layout:

The red line is a trace in another layer
The problems is that when the input voltage reaches 20V, the output voltage drops to almost 0V and the converter stops working. I've tested it for different values of RT, RSEN and inductors, even with a different layout but it didn't solve my problem.
What are your thoughts on that circuit?


texts:
May I know that when we want to estimate outdoor transmission performance between two wireless points, which model,Two-Ray Ground Propagation Model or Free Space Propagation Model is more suitable?

Thank you.


texts: What would be the peak voltage value of two combined signals (one noise and one sinusoidal signal)?

texts:
As I learned before, the peak voltage value of two combined sinusoidal signals is the sum of the two amplitudes, for example, \$0.6\sin(ax) + 0.8 \cos(bx)\$ can be \$+1.4\$V or \$-1.4\$V. Would it be the case for the noise?

For example, if now the output noise signal is \$1\$Vpp and my desired signal is \$1\$V at \$1\$kHz. Would the peak value of output become \$+2\$V or \$-2\$V?

One more question: If the answer of the above question is yes, would an amplifier which limits its output to the range \$\pm1.5\$V saturate at that time?


texts: How much power does a “smart meter” use?

texts: How much electrical power does a typical domestic “smart meter” use on average, in watts, for its own operation? I have searched the internet for an answer to this question but have been unable to find one.


texts: Are there any effective estimates for up-rating resistors power capability by adding airflow?

texts:
I'm considering using a bank of resistors similar to this:

http://www.vishay.com/docs/31842/fve.pdf

300-400 watt "corncob" wirewound resistors. I understand that they can be run over their spec'd rating continuously with appropriate airflow. But how much over? Is there a reasonable way to calculate, estimate, or look up how much additional CFM corresponds to how much power rating increase?


texts: Operational Amplifier Circuit - +/- Signal to 0 ... 5 V

texts:
I know that this question has been ask in similiar ways already. Since I am rather new to Electrical Engineering and I don't want to waste material I wanted to ask you guys first if my approach is feasible. So basically I think I already solved the problem but still need some feedback.

Problem

In order to measure a position, I want to move a permanent magnet between two hall sensors and calibrate the output to the position of the magnet.

I have two hall sensors positioned at x = 0 and x = L, each of them is delivering an output voltage V_1 and V_2 ranging only from 2.00 V to 2.01 V, depending on the position of the permanent magnet. I am using a Arduino to read the signal (0 ... 5 V, 1024 bits, 256 "effective" bits). I am interested in the difference between the two voltage levels since it is correlated to the position of the magnet.

Approach

I wanted to combine a differential OAmp (left part) and a simple potential divider (?) as shown below.

simulate this circuit – Schematic created using CircuitLab

Question

Do I really get this output voltage? Or is this unrealistic? Thank you very much in advance!

Cheers,
Urs.

Links:

https://www.mikrocontroller.net/articles/Operationsverst%C3%A4rker-Grundschaltungen

Level shifting a +/- 2.5V signal to 0 - 5V

https://ocw.mit.edu/courses/media-arts-and-sciences/mas-836-sensor-technologies-for-interactive-environments-spring-2011/readings/MITMAS_836S11_read02_bias.pdf


texts: I currently have four 12V 6A peltiers connected to PID's, heatsinks, a power supply and I use Labview program to control them. What I want to achieve is changing the temperature of the Peltier devices from 35 degrees C to 15 degrees C under 10 seconds. It seems like Peltier devices can't keep up with the changes in voltage, always follow with a delay and reach the desired temperature a little bit later than I want. I need suggestions for this. What causes this delay? With what kind of equipment, input changes I can fix the problem? How to decrease the temperature change time in Peltier devices?


texts: Trouble understanding how dependent current sources affect a circuit (Two-port networks)

texts:
While reviewing a problem from my recent test on two-port networks I noticed that it made its way online.

When someone was explaining the solution they utilized a point that I just completely missed. I wanted to ask about it here.

The line was in reference to this section of the circuit:
(https://i.imgur.com/lAYySZf.png)

The solution online noted that the current flowing from the top-right node in this picture was the current flowing in (I_1) minus the current flowing through the 25 Ohm branch (2V_1), or I_1 - 2V_1.

My main question here is to try and take away some sort of generalization that I missed during my basic circuits class. Does the dependent current source dictate the current across the entire branch? Doesn't that mean the voltage across the 25 Ohm resistor is always known to be 50V_1?

Sorry if this seems like too basic a question, but apparently between a poor circuits foundation and the circumstances we find ourselves in I am failing to understand something I should have learned last year!


texts: What is a Low Drop Constant Current Driver (LDCCD)?

texts:
In this post, the gentleman describes this device but does not give any details about how it works.  What's underneath the shrink tube?

The easiest way to explain my Low Drop Constant Current Driver (LDCCD) is as follows. It converts the voltage and current of the LiPo to a constant current and voltage suitable for the LED's included in the light set so the LED's remain a consistent brightness as the LiPo discharges. My LDCCD doesn't use resistors to reduce the voltage and current, resistors will shorten flight time as they use additional power to regulate the voltage and current.
For the Ladybird 8-LED Light Set the LDCCD I've built for this application takes the 240mAh and 4.2 V of the LiPo down to a constant 3.0V @ 30mAh for Blue, Green, White LED's and 2.7V @ 30mAh for Red LED's. This particular LDCCD will work with 2S @ 7.2V and 3S @ 11.1V as well.


texts: Is the resultant field of a three phase wound stator always two pole?

texts:
Suppose  I have a stator,  where I've allocated one coil for each phase and I supply a balanced three-phase supply. So the fields, $$B_r = B_{max}\cos(\theta_{mech})\cos(\theta_{elec}) \\ B_y = B_{max}\cos(\theta_{mech}-120)\cos(\theta_{elec}-120) \\  B_b = B_{max}\cos(\theta_{mech}-240)\cos(\theta_{elec}-240)$$ whose sum ultimately gives, $$B_{res} = \dfrac{3}{2}B_{max}\,cos(\theta_{elec}-\theta_{mech}) = \dfrac{3}{2}B_{max}\,cos(\omega_{elec}t-\theta_{mech})$$
which is a rotating magnetic field with a frequency of \$\omega_{elec}\$.

Now, what happens if I've allocated 2  coils for each phase such that each coil crates 4 poles, what will be the resultant field? Will it have four poles rotating? Maybe like this\https://imgur.com/a/hWxnfOm ?

Or does the first set of RYB produce a rotating field \$B_{res1}\$ and second set of RYB produce \$B_{res2}\$ (I've no clue for what's the phase-difference between these two resultants)and the final resultant a sun of these two will be two-pole?


texts:
I was looking through an LED datasheet for an LED I am using and came across some terms that I am not familiar with. I a new to electronics, and have looked on the internet for explanations, but they provide relatively (to me) in-depth and complicated answers.

(Continuous) Forward Current
(Zener) Reverse current
Peak Forward Current(Duty /10 @ 1KHZ)
Reverse Voltage
Forward Voltage

Electrostatic Discharge

Any help in understanding these would be great


texts:
I am developing a Liquid level indicator to be used for my lab breaker.
The purpose is to get real time liquid level data on computer for analysis.

I have searched for many liquid detectors, but mostly they use ultrasonic sensor on the top of container as shown below, but I want a sensor that could be fixed at the bottom of the container (not in contact with liquid) instead of at the top.

What technique/Principle or type of sensor could be used in this case.

Edit:- I want to know the level of any kind of liquid at any given temperature.

Thanks


texts: How is IEEE 802.11(Wifi) made robust to interference?

texts: I was curious to know how wifi is made robust to interference.How there is almost no interference between wifi signals from two nearby routers?


texts: Should I have to include photocoupler in SSR application circuit?

texts:
I'm designing simple circuit for ssr control.

I reviewed some sort of related circuits and previous version of the product(our company's)

Many of them are including photocoupler before S.S.R. control pin not in the diagram of S.S.R.

I thought S.S.R already has photocoupler in own module, so adding photocoupler is over spec or superstition.

Anyone use it for specific reason?

P.S. Surely I wanted to ask why the previous version has it, but there's no records, no one related with that.


texts: CC1101 Transceiver pair not working when relatively close to each other

texts:
I have a pair of cheap CC1101 boards transmitting at 433MHz.

(1): One oddity that first led me to believe that they weren't functional is the fact that they do not receive data when they are within approx. 1m of each other.

The antenna is mounted in parallel to the PCBs ground plane.

The issue could be resolved by setting the transmitting power to "PA_LowPower".

What is the reason behind this kind of behavior, why does the communication fail under the described circumstances (1)? Why can't the two devices communicate properly when in "Long Distance" mode?


texts:
I am considering to design memory controller handling 1GB of the RAM. I did already design controller for Micron's 32MB SDRAM in the past using Cyclone III device.

The new design is for retro computing, and there will be no need in high speed access, let's say access cycle would be ok at 100 ns. The main property is the size of the RAM, and it is a reason I am thinking about SODIMM (mobile computer memory module), which is socketed and easily replaceable.

The controller might be an FPGA (however I see DDR2 controller available in the MegaWizard), or anything else with preferably available building blocks.

The main issue I currently face is identification of the minimal clock frequency for the module. Chips' datasheets seem to have this information (e.g. MT41K1G8, page 73. table 54 - clock cycle is up to 3.9 us), but this information is not available for SO-DIMM modules (e.g. MT8KTF12864HZ) listing only "typical" 1.5 ns timing.

There's another document called DDR3 Point-to-Point Design Support listing at page 3 table 1 "slow clock debug" advantage of DDR3, with lowest clock to be 12.5 MHz (80 ns), but again, this document is for DDR3 chip rather than memory module.

Is there any body of knowledge which would help me to identify how can I apply DDR3 module for slow access in more or less cost-effective manner, or I am looking in wrong direction and there's even better way to put a GB into the retro computer?


texts: plotting a graph and finding the error(its more software and less electronics)

texts: I have found an output for a RC circuit from ltspice and then tried  predicting it using matlab. I converted both the data into text form and observed them by plotting. I want to find the maximum and average error ,  but number of points are different for the outputs (for ltspice is 635 and matlab is 747), so simple excel subtraction wont work. Is there any way to do it?


texts:
I am trying to make a device which can give x, y, z data and also can detect freefall and shock. For that I am using bma220 sensor. I am programming the sensor in 8g as I need shock values < 8g. Now as I put the sensor on a flat surface I expect x and Y to be near to zero while z should be near to 1. But I am getting changes in Y axis continuously. And those changes are almost 1/4 of 1 g so I can not neglect them.

Data directly from the sensor is

x = 0   y = -4   z = 20
x = 0   y = -4   z = 20
x = 0   y =  0   z = 20
x = 0   y =  0   z = 20
x = 4   y = -4   z = 20

The sensor's useful data is invfirst 6 bits in 1 byte, so I am dividing these values by 4 and multiplying with the resolution that is 250 in this case and those values becomes

x = 0   y = -250   z = 1250   //y value is very big
x = 0   y = -250   z = 1250
x = 0   y = -250   z = 1250

I need to know what value I should be getting at idle state? Am I wrong somewhere in interpreting something?


texts: Problem with load switching at capacitor resonant frequency

texts:
I was watching this video (EEVblog #1117 - PCB Power Plane Capacitance) where the author analyses the impedance curve of the capacitance formed between a PCB's power planes.

The comparison with a standard capacitor showed that the PCB capacitance has a less sharp resonant zone. The author argues that this is very good, because if you have a load switching at the "right" frequency, it would cause serious problems.

However, I always imagined that it would be good to have a capacitor that has an impedance valley close to the operating frequency, as it would be a better bypass.

So, what is the basis to avoid operating close to the resonant point?


texts: Root locus, where do they leave the line parallel to imaginary axis

texts:
I know how to sketch by hand root locus of simpler systems. Consider the root locus which Matlab gives for:
$$G(s) = \frac{1}{(s+4)(s+6)(s^2 + 10s + 100)}$$

I've marked the points of interest P1 and P2. When the following task was done during class the points were determined by solving for the breakaway point:
$$\sum_{j=1}^{n} \frac{1}{\sigma - P_j} - \sum_{i=1}^{m}\frac{1}{\sigma - N_i}  = 0$$
Which when solving yields a real solution and two complex conjugate solutions:
$$\sigma_1 = -5, \sigma_2 \approx -5 + j6, \sigma_3 \approx -5 - j6  $$
Obviously the breakaway point from the real axis is the real solution, however for the points P1 and P2 the two complex conjugate solutions were taken, respectively. I have been unable to find the reasoning behind that in my books and on the internet. My question is how do we determine the points P1 and P2 and why?


texts:
EDIT: Edited in response to question in comment (1)

I'm trying to work through some examples from Carmine Noviello's book, Mastering STM32.  In the chapter introducing timers, I adapted his very first example and am getting an "undefined reference" error for the function HAL_TIM_Base_Init.  I have other errors too, but one at a time...

Expected result:  This code should compile, link and create the target, as I have the .h file containing it in my Eclipse 'Includes Path' and am looking right at it in the header file as an "exported function".  As an example, the typedef TIM_Base_InitTypeDef compiles fine and it is in the same header file as the function that's throwing the error.

Actual result:

Invoking: MCU GCC Linker
arm-none-eabi-gcc -mcpu=cortex-m4 -mthumb -mfloat-abi=hard -mfpu=fpv4-sp-d16 -specs=nosys.specs -specs=nano.specs -T"../STM32L476RGTx_FLASH.ld" -Wl,-Map=output.map -Wl,--gc-sections -o "cubemx.elf" @"objects.list"   -lm
Src/main.o: In function `main':
D:\prj\NUCLEO-476RG-03\cubemx\Debug/../Src/main.c:112: undefined reference to `HAL_TIM_Base_Init'
D:\prj\NUCLEO-476RG-03\cubemx\Debug/../Src/main.c:113: undefined reference to `HAL_TIM_Base_Start_IT'
collect2.exe: error: ld returned 1 exit status
makefile:35: recipe for target 'cubemx.elf' failed
make: *** [cubemx.elf] Error 1

I used STM32CubeMX to create the basic clocks and setup GPIO, and all the calls from its generated code of course work fine.  But this one function, which I see online in numerous examples of timer setup on the STM32, for some reason cannot compile.  I cannot resolve this reference without some insight.

Source code (less the generated CubeMX clock and GPIO code, which is working):

#include "main.h"
#include "stm32l4xx_hal.h"
#include "stm32l4xx_hal_tim.h" // HEADER WITH THE FUNCTION IN IT

TIM_HandleTypeDef htim6;

/* Private function prototypes ---------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);

void TIM6_IRQHandler(void)
{
    HAL_TIM_IRQHandler(&htim6);
}

void HAL_TIM_PeriodElapsedCallback(TIM_HandleTypeDef *htim)
{
    if(htim->Instance == TIM6)
        HAL_GPIO_TogglePin(GPIOC, GPIO_PIN_0);
}

int main(void)
{
  HAL_Init();

      htim6.Instance = TIM6;
      htim6.Init.Prescaler = 47999; //48MHz/48000 = 1000Hz
      htim6.Init.Period = 499; //1000HZ / 500 = 2Hz = 0.5s

      __HAL_RCC_TIM6_CLK_ENABLE(); //Enable the TIM6 peripheral

      HAL_NVIC_SetPriority(TIM3_IRQn, 0, 0); //Enable the peripheral IRQ
      HAL_NVIC_EnableIRQ(TIM3_IRQn);

      HAL_TIM_Base_Init(&htim6); //Configure the timer ERROR
      HAL_TIM_Base_Start_IT(&htim6); //Start the timer ERROR

  SystemClock_Config();

  MX_GPIO_Init();

  while (1)
  {
  }

}

I feel as though if I could resolve this one error I'd have a pattern for resolving others that arise from generated library code from CubeMX under Eclipse and the OpenSTM tools and GCC compiler from AC6.


texts: How to create traces that don't touch for a four by four non matrix keyboard grid

texts: Hello. I have a potential design for a keyboard whose pcb I will make myself in eagle. This will use cherry mx browns (http://www.cherrycorp.com/english/switches/key/mx.htm for info.  Rather than use a matrix, I will connect each key to the arduino uno via daisy chained shift registers. The only problem I have is how to route connections for each of them without running into connections for other keys, as they will not be laid out in staggered manner. Attached is a rough draft of my layout. Keys on the left are for selecting which function a right key should perform. The three squares and one circle in the bottom left are mouse related and while they will be on the keyboard, they will not be connected via shift register. To summarize, how should I route the key switch-shift register connections?


texts:
I'm designing a capacitive proximity sensor for detection of human presence. My requirement is that I should be able to detect presence by monitoring change in capacitance at the highest possible distance for my plate size and configuration (I'm looking at a target range of 100-120 mm). I have a DC source of 24V. Additionally, I would also like to calculate approximate distance of the target from the sensor once the target is within range. Most importantly, the detection distance should be consistent and should have low susceptibility to noise. Looking at different approaches for measuring capacitance, I've found the following to be most commonly mentioned:

RC decay circuit
Oscillator circuit using a 555 timer
Op-amp integrator circuit

Which one of these best suits my application? Or is there any other approach that I've missed? What are the advantages and disadvantages of the above methods?


texts: Raytheon JAN-6080WB Vacuum Tube question

texts:
I found this and several more, inside a old ocilloscope, I found the data sheet on it.

6.6 v, pins 7, 8, are the heater pins, but when i put power on it, i do not get a glow. are pins 7 and 8 where i put one + or - connection and somewhere else the power completes the circut. It is my first time messing with a vacuum tube.

tested with my meter, and it chrips away to tell me there is connection. i have even visually inspected under my 10x magnifyer, and there are no broken connections.

what am i doing wrong? why will it not glow? its for a prop project for my brother.


texts: Will this circuit protect my digital IOs from overvoltage conditions?

texts:
I have come up with the following circuit to protect my device's IOs from overvoltage conditions.

simulate this circuit – Schematic created using CircuitLab

The idea is that as soon as the input voltage is higher than D2's Zener voltage M1 will shorten M2's gate to it's source and disconnect the input from the output.

The main reason for this protection circuit is to protect the rest of the circuit from accidental misconnections (e.g. accidentally connection In to 12V). D3 is there to prevent transient voltages from damaging the circuit.

My question is: Does this work? What happens if the input voltage is less than 0V? I think it also lockout negative voltages which would be desirable, but I am not sure.

UPDATE:

I am not too worried about ESDs because they are short and the TVS diode D3 should be able to handle them. My main worry is a high constant voltage (12-24V), when the circuit to be protected is only rated for 5V.

UPDATE 2:

I added a fuse (PTC) to protect against overcurrent, because it has a lower resistance than a series resistor in normal operation. But my main question is still if the cicuit will work as expected or not.

UPDATE 3:

Turns out I didn't have to qorry about the voltage drop across the series resistanse. After simulating it I found that there will be a voltage drop across M2's source and drain if it's drain is connected to ground. Therefore the input voltage can never be pulled low.


texts: How is ASIC design different from FPGA design? Do you write HDL (Verilog, VHDL) to design and ASIC the same way you would for an FPGA?

texts: From my limited understanding i feel as though one could just take the synthesis output from Verilog/VHDL code and then use that design to fabricate on silicon the sea of gates.


texts: Cadsoft EAGLE Some objects extend outside the allowed board area

texts:
I'm trying to Modify an eagle file that I have, it's a relatively simple circuit and I'm using the free version of Cad soft Eagle to do it. One of the components on the board is a 4 pin plug, I'm trying to add another 4pin plug and map it to one of the terminals. The circuit is small (2" x 1") and I am able to modify it, but when I try to add another 4 pin connector or copy the existing one, I get the following error "Some objects extend outside the allowed board area". which makes no sense, because the component is clearly within the board area.

Any idea how to get around this error?

Here is a screen shot of the layout

For some reason this is the only spot on the board where moving J2 does not throw that error, can't figure out if perhaps it's something weird with the component.


texts: adding a switch for direction reversal in 12v DC motor w/ PWM controller system

texts: I have a circuit for a 12v dc motor with a battery and a PWM controller. the system sort of is in this order battery-->PWM-->motor. I want to add in a switch to reverse the polarity to switch directions of the DC motor at will. Without the PWM, its a pretty simple operation and straightforward, but I was wondering how to do it now with the PWM. Do I put the switch after the pwm before the motor or between the battery and pwm? I wasn't sure how the PWM would affect the system direction and didnt want to ruin anything in my system while implementing the new switch


texts: Substitute for 455 kHz Ceramic filters in new designs

texts:
I was wondering what has ever happened with the 455 kHz ceramic filters commonly used in the second IF stage of a superhet radio receivers?

All but just a very few (and those left over don't seem to stock them anyway) don't manufacture anymore and are marked as discontinued.
Murata, AVX etc used to have them and there is some stock left about with the standard distributors, but now obviously marked as NRND and obsolete.

For a new design I would require as much as possible off-the-shelf parts so my immediate search was for this 455 kHz component thinking it would be easy to find. This is the case for the 45 MHz first IF stage crystal filters which seem to be a lot more common (eg Goledge), but not the case for these formerly readily available parts anymore.

Anyway, other alternatives such as active filters is always an option. But in the meantime,

somebody might shed some light on the gradual disappearance of these formerly standard components?
Anybody knows why other than "no demand" perhaps, given there are stil many radio chip-sets that call for this second IF stage?
Or is there an alternative more commonly used that has superseeded
this ceramic filter?


texts: Microprocessors/Microcontrollers - Do registers have addresses?

texts:
My Embedded Systems professor keeps referring to the memory locations of registers as their respective "addresses". I'm confused by this; I was always under the impression that in any microprocessor, the CPU registers don't have addresses since they don't reside in the main memory (they reside in the microprocessor itself). I am also confused about what we refer to when we say the "memory location of the register" - again, it's not in main memory.

With that said, why are we referring to the locations of the CPU registers by "addresses"? Do all/some registers have addresses?

I thought about this and reasoned that maybe they're "connected" to certain main memory locations, allowing access to the values stored in the registers. To extend this thought, is this what memory mapping is?

I should also add that we are working specifically with NXP's LPC1768 microcontroller, which uses the ARM Cortex-M3 microprocessor.


texts:
I'm making a buck converter, this is the circuit I've:

The average voltage at the output is ok, but I'm getting lot of noise at all nodes of the circuit:

I'm using as a main source a 30V 5A bench power supply, and linear regulators 7815 and 7805 to power the circuit.

This is the voltage at the output:
The average of the signal is 15V  and I'm getting an overshoot of 2vp
I'm using a 10x probe.

This is at the output of the 7805, here I'm getting about 1.5Vp of noise

And this one at the output of the 7805,  here the noise is about 1vp

I'm using Manhattan wiring for the power stage:

starting with the input capacitors, 2*479u + 1*0.33u

the control stage is in a breadboard, wires from IR2110 to the transistor gate and source are about 6cm each.

Finally the load is a 8 ohm resistor.

This is the complete circuit:

Edit:

That's how I'm measuring the voltage at the output of the 15v regulator.


texts:
I'm reading the MCP1702 datasheet and there's the typical circuit on page 2 depicting a 9V source and a 3.3V 50mA output.

My question is: How come the current output is 50mA when the spec says that when Vr < 2.5V, Vin > 3.45V the min. output current is 200mA? How is the output current determined? Why is it 50mA?

Thanks for the help


texts: In Circuit Emulation vs On Chip Debugging?

texts: I am using code warrior to debug my code which is dumped on to the NXP Board. By definition would code warrior belong to the In circuit emulator or the On Chip Debugger. I am not clear about the definitions from the web resources.


texts: Multiplex usage of I/O pins: PWM pulse output + UART

texts:
I have the problem, that I have a device with limited output pins and want to know if it is possible to implement a multiple pin usage with additional HW/SW (time multiplexed mode).

In my case my device is a flow meter (based on an ARM Cortex M0 STM32L051) and has by default a pulse output on two pins (which are intented to transmit a PWM signal in push-pull mode via the I/O driver: iC-Haus iC-DXC3).

The other usage I want to overlay these two pins is for a UART communication (RX/TX). Just for the case of service use, like firmware upgrade.
The UART functionality should be only available just after boot the device for a short time slice (e.g. 5 seconds). After that period the pin shall switch in the pulse output mode until the next reboot.

Can someone please explain me, if this would be possible in general and if yes perhaps give some hints how that could be realized?


texts: Voltage Divider for Comparator Threshold

texts:
I am trying to understand how the voltage on the negative pin of U2A of the below circuit is 1V/2.4V.  From the author: "Threshold signal is 0V/5V but it changes the voltage on the negative pin of the comparator from 2.4V to 1V (approx)."  I have seen multiple blogs that agree with this statement. But the math and simulation show voltage at negative pin as being 1V/3.9V with threshold signal of 0V/5V.

Am I missing something or is the schematic wrong?

This image shows how I did the math to get:
1V when V1=2.5V, V2=0V and 3.9V when V1=2.5V, V2=5V


texts: Can I detect whether bytes are getting dropped by the Arduino Serial driver because of buffer overflow (i.e. if I'm not keeping up with my input stream)? If so, how?


texts: AVR Microcontroller board capacitor recommendations

texts:
I am designing SAME70 board with space quite limited, using LFBGA-144 package. According to datasheet it is recommended to place decoupling capacitor nearest to the concerned pin. Due to space limitation I can't use separate capacitor for each line. Is it possible to use one consolidated capacitor for decoupling purpose? The capacitors recommended are MLCCs or tantalum. I'm not going to use tantalum and instead of MLCC I want to try out the new Low ESL NFM series that would reduce the number of these bulk capacitors by approximately 10 and in my case I'll use one instead of using 6. Is it possible that reducing the capacitors per pin affect the performance of my chip if the capacitance of the consolidated capacitor is equal to the sum of the capacitors recommended by the datasheet? I'd like to know beforehand if it would.
Thanks waiting for reply.


texts: Can I operate a 4-lane MIPI DSI Display from just one lane connected?

texts:
I was thinking to integrate a MIPI display into a project with a STM32L4R9 processor, which in my package of choice exposess only 1 of it's two MIPI lanes.

The data sheets of all displays I viewed where rather mysterious about how to operate, but most of them had 4 lanes on the connector side. (data sheet example)

My question now is, can I operate a 4 lane MIPI display with just one lane connected, or do I have to search for a one lane display particularly?

Thanks for any help!


texts:
I'm new to PCB soldering. I just bought a cheap soldering iron, solder wire and flux to try something. I have no previous experience with soldering.
I'm well aware of the potential risks of prolonged exposure to flux fumes, and I have already taken precautions to avoid it.
I was all excited and ready to start soldering, when I saw this on the flux box:

I'm OK with not putting that into my eyes and not tossing it into the waters, but why does it say "CAUSES SEVERE SKIN BURNS"?
All the dudes on YouTube that I saw soldering touched rosin with their bare hands.
While that doesn't necessarily means it is a safe practice, it surely didn't cause severe skin burns! I would rate something as severely burning if it burns like sulfuric acid, for example.
The only explanation I came up with was that maybe this product is made of really cheap dangerous stuff instead of rosin.
The product is this:

However, looking online I saw the same warnings even on boxes clearly marked as containing rosin flux.
If all those people on YouTube can handle this stuff barehanded, I'm clearly overreacting.
So I ask you, why is this stuff depicted as extremely dangerous on the box?

Can I safely touch it?
Are those warnings put on the box only for legal reasons?
Are rosin based and different fluxes more or less dangerous?


texts:
I have an Arty A7 board with Artix-7 FPGA from Xilinx.
from the datasheet, I see that the micro-usb cable can be power up the board and also used as a jtag cable for programming the board and communication with the PC.
My question is, using the Arty A7 board, the micro-usb cable can be used both as a power source and jtag cable for the board? I can also power up the board and program the device at once using the micro USB?
Because I still don't have the compatible power source cable for this board and I'm using the micro-usb cable to power up the board, but when I trying to program my design into the FPGA, Vivado software can't identify the board.
Someone using the micro USB cable with Arty A7 board as a power source as well as jtag cable?
thanks.


texts: Programming several AVR MCUs simultaneously? (with parallel)

texts:
I was able to program three ATMEGA32 simultaneously using ISP.

In your opinion, can I program several AVRs at once with parallel? Unfortunately, I do not have a parallel programmer. Can you test it for me?

I don't know, how it's work? I already thought it shouldn't work! How many MCU can I program together?


texts:
I have attached a 2N7000's gate to my AVR chip output pin. I am sending a PWM signal to it.

I am powering my AVR chip from 3.3V power source so the maximum voltage it can output at G is 3.3V. Then across drain and source is connected my motor which is powered by 6V. Even at maximum G voltage of 3.3V, the voltage across drain and source does not go above 4V. I simply can't understand the relationship between the gate voltage and voltage of the load. Could someone please explain it to me plainly with some examples like what will happen if the motor was powered with 24 volts instead of 6V?


texts: How to ground a 2 prong plug electronic?

texts:
I am installing a strip of 110v led strip outdoors and placing them on an aluminum channel. I will be cutting the strip, waterproofing them and placing different sections of the strip throughout the channel.

What I am worried about the most is eventually the weathering may/will cause a short or ground fault, and it will become dangerous to touch the aluminum channel.

From what I see the led strip is powered via mains to a rectified 110v DC, and only comes with a 2 prong plug.

Is there anyway to wire/rewire the led strip such that it can detect a ground fault from a 3 prong outlet.


texts:
I found this article:

midi-in-through-out

Credits by Zynthian

I like that it has notification LEDS for MIDI in/out/thru.

However, I also notice there are optocouplers for MIDI Out and Thru, while the MIDI electrical spec, page 2/3 only defines an optocoupler for MIDI In.

Is this overprotection or are the additional optocouplers useful?


texts:
What I understand from Faraday and Lenz laws is that(I might be wrong): a voltage appears across an inductor when the current through it changes. And the polarity of that voltage is such that it opposes the increase of flux. In other words voltage appears in a polarity such that it tries to maintain the current.

So if we look at the below illustration:

Above the current increases in the shown flow direction. So the flux increases. According to law of induction v = L*di/dt. For polarity I assume that the voltage induced should oppose the flux or try to stop the increase in current. So I marked the polarity of the voltage I guess.

But obviously Im wrong, after seeing some examples in texts.

And here is a simulation(V(A,B) is the voltage across A and B) result also disapproves me. When the current increasing the polarity does not oppose the current:

Where am I wrong here in my thinking? Can you explain intuitively what's happening?

Edit:

Here is the figure and the argument from the text which confused me:

  The voltage developed by the change in flux linkages has a polarity
  such as to oppose the change in current producing it. A current i,
  increasing in time in Fig. 1.7(b) or (c) induces a voltage +v as
  shown, thereby opposing a source which tends to increase i:

Is the book correct?


texts: What are the components used for the iPhone-sized car hack?

texts:
Recently two security researchers hacked a car with iPhone-sized gadget according to this link.

They didn't release any technical details, but I think we can guess from the picture of the gadget:

That it's based on some popular components like Arduino pro, and it uses Bluetooth.

I would like to identify all electronic components used in this hack starting from the published picture.


texts: How to harden electronics to protect it from EMP(Electromagnetic pulse)?

texts:
My question is about hardening electronics against EMP, Electromagnetic pulse (e.g. from Nuclear burst).

I'm looking for civil solution. For electronics, that not build properly against EMP, like e.g. military radar systems.

For example, Is there way to hard civil satellite antenna against such pulse (e.g. against lightning). Without rebuild inner circuit.


texts: Differences of Solder Gun, Heat Gun? (In Ref. to PS3 YLOD)

texts:
I'm a programmer. I'm also a hardware noob. Please excuse my ignorance.

I'm trying to fix my YLOD (Yellow Light of Death), and I'm assuming (foolishly) that my system has suffered the most common failure; the solder connecting the CPU/GPU to the motherboard has cracked or melted. I figured that to fix a solder joint, you would use a solder gun. But I keep hearing people talking about a heat gun. Me being a hardware noob, I don't have the slightest clue what the difference is, if there even is one. I was hoping I could just whip up a fix with a solder gun my friend owns, but if this involves buying a heat gun, forget it.

So, what is the difference between these two tools, and can a use a solder gun to fix this problem?

Note: I only need a temporary fix. It can work for 2 hours and I'd be happy.


texts: Can long-range radio waves from an RTV tower penetrate thin plastic composite material next to its source?

texts:
We are currently developing a conceptual design for the renovation of Croatia's main RTV tower located on 1033 meter tall peak Sljeme at the Medvednica mountain north of Zagreb. The idea is to renovate and reopen its upper gondola for touristic purposes (as a revolving restaurant and viewpoint towards Zagreb metropolitan area, as it was initially intended) and to build another floor of apartments on the roof-top level of a lower maintenance and equipment gondola. Basically, the wish of the investor is to make it an important landmark of Zagreb and place its touristic purpose, which it was lacking since its construction ended in 1976, because it was only opened for public 2 years, above its primary function which is receiving, boosting and transmitting radio, ATC and television signals in a radius of approximately 100 kilometres.

However, after our social studies and researches, we determined that this investment would be absolutely useless because nobody considers it as an important landmark which tourists should, or would want to visit just because of that, considering its distance from the city and long drive to reach it. As you can see in the picture below, the body of this monstrosity is completely covered with antennas and aesthetically it looks unpleasant and way too much utilitarian. My problem is that I absolutely have no idea what these devices are. Are those receivers or transmitters?

Our concept and solution is as follows: we want to envelop the tower's central body, beneath the upper gondola and part of its lower gondola with organic, deconstructivistic "curtain facade" made out of highly perforated (ca. 60%) approximately 5 mm thick lightweight plastic composite material panels, to visually "hide" those antennas behind, and to give the tower a brand new vibrant composition mixed with LED lights for night light shows, which will make it very eye-catchy from Zagreb and all surrounding cities.

From my personal research and previous general knowledge about long-range radio waves, which are transmitted and received by this tower, is that this should not affect its performance, because of the wavelengths and frequencies of those waves as such, they would just slice through this median without reflection and deviation of direction with minimal losses in strength. There are also some radome plastic materials which we could use to implement this, in which antennas are usually covered and that could be used for this.

Is that all above correct, or will our intervention of this kind render the tower completely useless and we will leave half of Croatia without ATC, radio and TV broadcast coverage? Keep in mind that this is only a conceptual idea we are considering to implement, and it will anyways probably be rejected and scrapped by the investor. We just want to know if it's okay to go out publically with this project as we imagined, or will we embarrass ourselves proposing something as ridiculous as that? I'm still just architecture and civil engineering student with minimal knowledge in electrical engineering and stuff alike, so if someone could give me some advice or answer my doubts about the idea above, it would be highly appreciated. I am sending you a link to some public documentation and specifications about the tower and the channels types it is broadcasting.

Wikipedia: Zagreb TV Tower

Technical documentation with diagrams and illustrations:
https://hrcak.srce.hr/file/18627

Recent image of the tower and antenna cluster it is equipped with:

The upper steel antennas painted in anti-collision red and white pattern are none of our interest, only the antennas installed on the platforms around the tower's central body. Can someone recognize what are those for, and can their path be obstructed with described panels above, without significantly influencing their work on a daily basis?

Many thanks in advance for your time and understanding, I would highly appreciate any feedback and thoughts about our idea and if it can eventually be implemented.


texts: Amplifying pulse signal (0.1 .. 0.5V) to Arduino digital input

texts:
How this can be so difficult (to me :-). The incoming sensor signal rests close to 0 Volts and gives ~ 0.5V pulses, which needs to be read by Arduino digital input (interrupts).

So far, what I have tried:

0.5Volts is just under optocoupler to function, that would have been easy.
Reading directly this small signal to Analog input. OK, but timing is not enough accurate. So, definitely want to use Arduino digital interrupt.

When sensor sends 0.5V pulse -> 5V to arduino digital input HIGH state. If sensor signal goes under 0.2V -> Arduino digital input to LOW state.

OK, OP amps perhaps, but how? Have tried to simulate, without getting right things around suitable op amp.

I have single DC supply +5Volt to drive things.
I would like to keep component amount small, tiny package.


texts: I'm building an IoT device with a Wemos D1 Mini. It should control a relay, and also measure the temperature. The thing is, my only practical power source comes from my garage door opener which I measured to be 25.1V. What would happen if I then use this powershield rated for 7-24V? If it won't work, what are my options? Maybe I could make my own shield with higher input range, but that seems to be a lot of work.. What are my options?


texts:
I'm a recently-graduated electrical engineering student and I've been testing storage capacity of inductors and capacitors in simple DC circuits for circuit control. I wound up making the circuit below.

My confusion with the circuit is the behavior of D1. If the switch has been closed for a few seconds and I open it quickly, D1 lights up very briefly (milliseconds) which is as I expect. The inductance is small so the energy dissipates quickly.

However if the switch is open and I close it very quickly D1 ALSO lights for a few milliseconds. Based on my understanding I can't work out how there could be a voltage across D1 at any point when the switch transitions from inactive to active.

Can anyone please shed some light or why this might be happening? Is it simply due to the non-ideal nature of real components or am I missing something?

Thanks in advance!


texts:
I've connected the sensor this way, from Sensor to Board:

VCC -> 5V

GND -> GND

Trigger -> PD15 ( same as blue led )

Echo -> PA0 ( same as user button )

My C program send the trigger, reads the input and calculates the distance in cm.

However as I lack basic electronics knowledge, I'm worried this setup might damage the board or sensor.

Do I have to add any resistor or diode or anything to protect the components?


texts: pic32mx220 won't enter uart rx interrupt handler

texts:
I'm kinda new to pic32 and have been trying to get the uart to enter the ISR when it receives a byte on the Rx pin. My uart setup works fine both sending and receiving (if I use blocking to read the received byte). But I want to use interrupts to achieve a more 'realtime' feel (since the pic is doing a bunch of other stuff).

This is my code for configuring the uart and Rx interrupt:

INTCONbits.MVEC = 1;

// Peripheral Pin Select
U1RXRbits.U1RXR = 2;    // Set PA4 to RX
RPB15Rbits.RPB15R = 1;  // Set RB15 to TX

// UART1 Configuration
U1MODE = 0;
U1MODEbits.PDSEL = 0;
U1MODEbits.STSEL = 0;
U1BRG = Baud2BRG(9600);

// Configure UART1 RX Interrupt
IEC1bits.U1RXIE = 0;    // Disable interrupt
IFS1bits.U1RXIF = 0;    // Clear the interrupt flag
IPC8CLR = 0x001f;       // Clear priority vector
IPC8bits.U1IP = 7;      // Set priority
IPC8bits.U1IS = 3;      // Set sub priority
IEC1bits.U1RXIE = 1;    // Enable the interrupt

// Enable UART1
U1STAbits.UTXEN = 1;
U1STAbits.URXEN = 1;
U1MODEbits.ON = 1;

And for handling the interrupt:

extern "C" {
    void __ISR( _UART1_VECTOR, ipl7SOFT) uartRxHandler(void)
    {
        IEC1bits.U1RXIE = 0;    // Disable the interrupt

        Serial1Tx( "works");

        IFS1bits.U1RXIF = 0;   // Clear the interrupt flag
        IEC1bits.U1RXIE = 1;   // Enable the interrupt
    }
}

I just send a simple message back to see if it ever gets into the ISR. I can't understand why the interrupt is never triggered. Thanks for any assistance.

Edit: I'm using MPLAB X with the XC32 compiler and a PICKit3 to program


texts: Understanding Kirchoffs laws [elaborate example]

texts:
I'd like to help a fellow student in getting the ins and outs of Kirchhoff's current and voltage law. Thing is, it's been a while for me...

I remember that the current law dictates the sum into and out of a node to be zero, and the sum of the voltage inside a loop again zero. I may also assume the initial current directions.

The circuit in question has 10 resistors and five ideal voltage sources.

I am not sure if I may do that, but IIRC, I can combine those resistors that are in series (same current). That is, R1, R2 and R3 become R123 (3k), the same goes for R7, R8, R9 and R10 (3,45k).

This yields I1 - I5 as the unknowns so I need a system of five linear equations:

Loop 1: 0 = V1 - I1 * (R1 + R2 + R3) - I2 * R5 - V2
Loop 2: 0 = V2 + I2 * R5 + V5 - I4 * R6 - V3 - I3 * R4
Loop 3: 0 = V3 + I4 * R6 - I5 * (R7 + R8 + R9 + R10) + V4
Node 1: 0 = I1 - I2 - I3
Node 2: 0 = I3 - I4 - I5

Plugging this into Mathemathica I get

I1 = 2.1 mA
I2 = 0.36 mA
I3 = 1.74 mA
I4 = -1.72 mA
I5 = 3.45 mA

I am not so much interested in the actual values but if my understanding is correct.

Thanks for reading!
Chris


texts: Design buck converter to meet output ripple voltage specs

texts:
I am stuck at calculating output ripple voltage with non-ideal components for buck converter. As you can see from the picture, the output ripple voltage caused by each individual component is calculated.

However, how about the total output ripple voltage? Is it equal to sum of ripples caused by individual components?

Another point is that with given output ripple voltage specs, how do you choose inductor and capacitor along with their equivalent series resistance values to meet the output ripple specs?

(output ripple voltage specs is 1% of output voltage)


texts: Photoresistor power switch for arduino, does this look correct

texts:
edit: uploaded schematic: I am a novice, this diagram may not be correct but should convey the attempt.

I want to turn-on power to an arduino microcontroller when it is dark.

I white-boarded an example and uploaded the diagram below.

Power

Using a photoresistor and a transistor, I plan to switch the high side that carries power to the arduino from a 5v dc adapter (eventually a battery pack).

Arduino: https://www.arduino.cc/en/Main/arduinoBoardDuemilanove
ARD_PWR: 5v regulated power input of arduino
ARD_GND: ground port of arduino
ARD_OUT_1: An output pin of the
arduino, with 5v
ARD_OUT_2: Another output pin of arduino,
with 5v

LEDS

I plan to control 5v power to the LED's through the arduino's output ports, and use 200Ω resistors to regulate the current on the ground side.

Question:

How do I determine the resistor values for R1 and R2. I'm new to EE and ohm's law, sorry.

Is my logic sound? Is this terribly inefficient?

Reference


texts: ESP32: Power rail transient when using SPI on battery

texts:
Working on a small datalogger project using an ESP32-WROOOM that involves an analog sensor signal being recorded and saved to SD card. Having a big power rail spike issue that has been isolated down to the SPI. Setup is as follows:

Core → ESP32-WROOM
Power circuitry for USB and battery
Peripherals:

a. Sensor (Analog input)

b. ePaper screen (SPI)

c. SD card (SPI)

Channel 1 (yellow) is the 3.3V rail, Channel 2 (Blue) is the SPI clock:

Note:

This issue only occurs when the setup is powered on a 3.7V 1200mAh LiPo battery.

There is no WiFi or Bluetooth in use.

Circuit has been decoupled with bulk caps.

USB: Stable 3v3 and no power dips/ spikes appear during the record procedure.

BATTERY: When the code enters record mode there are significant power dips on the 3v3 rail that appear to be caused by the SPI (SCLK & MOSI).

The only difference between the power input circuitry is that the battery circuit utilises a power trench mosfet whereas the USB goes through a shottky diode.

This is how power gets into the circuit:

The power rail spikes are affecting the 3v3 rail to the extent that the sensor readings are getting completely messed up.

Wondering if anyone has experienced something similar? Sense is that it is a battery/ current limiting issue or something to do with the ESP32.

Closer views of the noise spikes:


texts:
How do I assign certain pins to the appropriate FSMC pins? I've looked through the reference manual and the examples, but there's nothing about pin assignment except configuring them as alternate push-pull. If it helps, I'm configuring the FSMC for an LCD interface.

Thanks.


texts: Why are master-slave D flip flops preferred for pipeline stage buffers?

texts: I'm watching a lecture on designing pipelines in HDL, and it's mentioned that the buffers (for intermediate values) between pipeline stages should be master-slave flip flops to avoid race conditions. Why is this preferable to common edge-sensitive D flip flops? Looking at other places where similar questions were asked, I find answers of why the T operation in JK flip flops causes a race condition (not relevant to D flip flops) or why a master-slave D flip flop must be used instead of a D latch (obvious). What are the differences between a standard edge-triggered D flip flop and a master-slave D flip flop and why is the latter preferable?