texts: Designing amplified speaker for legacy car navigation system

texts:
We have a 2003 Honda Odyssey with built-in nav and stereo.  The two were integrated -- the nav audio went through the stereo, there was also a mute signal to signal the stereo to play the nav audio on the front speakers.

I replaced the stereo a few months ago which severed any navigation audio.  We bought a BC23A 15 watt powered speaker as a workaround.  After wiring it to the nav system, the audio was too quiet.  (I turned the powered speaker up, and turned the nav system all the way up.)  Hooking the BC23A directly to an ipod gave me audio much louder than I needed, so I know the speaker works.

My assumption is the line level from the nav system is too low for what the BC23A is expecting.

I began thinking I should make/buy a small amp to raise the line level before it gets to the BC23A.  Then I found the MAX9744 at adafruit.  The specs say:

  The outputs are Bridge-Tied-Load which means you can only connect speakers   up directly. Don't connect the outputs to another amplifier!

So I can't put it in series with the BC23A.  Then I realized that this amp is probably sufficient to replace the BC23A.

The specs for the MAX9744 say this about the input level:

  This audio amplifier takes in stereo audio, either using a 3.5mm stereo jack or terminal blocks. Line in audio is a-OK. The audio inputs are not differential! The ground connection is connected directly to the power ground, this chip simply does not handle differential inputs. However, the inputs do have blocking capacitors, so if your audio levels have DC bias, its OK to connect them up directly without extra audio blocking caps.

I believe this is sufficient to put in and connect directly to a speaker, maybe recycling the BC23A as a non-powered speaker.

A friend suggested I amplify as near the source as possible -- so I am thinking of running the amplified output from behind the stereo to the remote speaker, rather than running line level to a modded BC23A.

My questions:

Does this sound like a reasonable plan?
How important is it to place the amp near the source?  It would be convenient to just gut the BC23A and put it in there!  (Maybe I should just do that initially since this isn't hi-fi music we're talking about.)
I would like to use the "stereo mute" signal from the NAV system to turn the amp on and off -- to reduce hiss when not operating.  The amp has a SHDN pin that shuts down the amp when grounded.  I believe the nav system has a mute signal (high) when speaking.  What's the simplest / reliable way to switch this?  Is it as simple as this?  What value should R be?

                              R
  [MAX9744 SHDN] ----+----\/\/\/\/\--- [MAX9744 GRND]
                     |
                     +----- [NAV MUTE]


texts:
I am trying to simulate a buffer with an op-amp using CMOS, I am using Cadence. The gain I am getting is low (16dB). I am trying to reach a gain of 90. how can I increase it?

https://www.ti.com/lit/ds/symlink/opa358.pdf?&ts=1589808642619


texts: swapping the ground reference on a transformer's secondary winding

texts:
I'm looking to build a [simple] high voltage power supply in order to make electrets via corona discharge. I'd like to be able to fabricate both positively and negatively charged electrets using this method, ideally with the same power supply requiring only minor configuration changes.

Right now, I'm leaning towards using a "wasted spark" automotive ignition coil which has both ends of the secondary winding exposed as such:

The logic behind opting for such a coil is that they're plentiful (i.e. cheap), can generate 30+ kV, and some are easily interfaced with needing only a 12V supply and a logic-level signal for pulse triggering.

Based on my understanding of the corona discharge method used to make electrets (but not the "triode" method), the insulator that you're making the electret from sits on a grounded metal plate, and then some electrode (be it a wire, or needle/s) sits above it at either a high negative or positive potential depending on the charge on the electret desired, and produces a corona discharge.

So my question essentially boils down to this: assuming nothing on the primary side of the transformer changes, is swapping the polarity on the secondary as simple and switching the two output leads, and grounding the appropriate leg?

Also, I may want the output to be DC. If I'm to add a blocking/rectifying diode and filter caps, can I still easily swap the polarity? If so, would I do that after the diodes+caps?


texts:
I recently bought this ceiling speaker (http://www.3acctv.com/upload/uploads/Specification/T-103C.pdf), as shown in the PDF it has 3 wires attached to it. I am no expert in this, so I was wondering if someone could help explain the difference between the 3 wires.

I do understand the concept of +/- wires and how to connect them, the fact that this speaker has 3 wires baffles me though.

Thanks!


texts: Signal Integrity and clock waveform measurement

texts: Where do you probe and measure the signal quality of a clock signal that has series termination? Do you probe at the end of the series resistor that is pointed towards the load? Or do you measure at the load itself?


texts:
I'm trying to wire a PSC motor for use outside of a washing machine. I need some help identifying the wiring and where the capacitor should go.
The model is WH20X10063 and I attached the only documentation I could find for it. I believe this is a reversible model since it has 5 wires, but I only need it to run in one direction. So I shouldn't need all the relays listed in the schematic. The wire colors are red, orange, yellow, violet, and blue, with the resistance values below.
R-V = 5.6 Ohm - auxiliary winding?
O-Y = .1 - ?
O-B = 2.2 - main winding?
Y-B = 2.2 - main winding? but with two, is one reverse?
I think the capacitor goes between the red and yellow wires. I think orange is the overload switch and doesn't need to be hooked up. I think violet might be neutral. I'm not sure what blue is, maybe speed control.


texts: Power supply turning off when a motor is stopped then quickly turned back on?

texts:
When I stop my 12V wiper motor, then turn it back on within a second or so, my 12V 5A cheap power supply turns off for less than a second, and comes back on, then turning on the motor. What causes this?

The motor's stall current is 4A at 12V, if that's relevant. And I'm using a diode to protect a transistor connected to an Arduino which switches the motor on. Very infrequently, this problem does not occur and I'm able to switch the motor back on immediately after turning it off.

Anyone know what's going on??


texts:
I am currently designing a processor on an Altera DE0 Nano and found out that the power consumption of my design may be computed by this equation:

P = C * V^2 * (a * f)
where P is the power consumption/sec, C is the capacitance, V is the voltage, a is a constant and f is the clock frequency.

Can someone help me understand how to get the values for C and V? TIA.


texts: At what current and voltage do typical resistors explode?

texts:
I don't have an explosion chamber, so I cannot test critical values.

If you explode resistors with too high current-voltage combination, does it damage your equipment, such as multimeter and DC-supplier, even in the explosion chamber?
How do I notice when a critical point for resistors is achieved, not touching the hot component?
I want to test a Zener diode for increasing voltage. I have a great amount of different diodes, but I have no idea which ones are Zener diodes. Which resistors and Zener diodes should I use and how do I find the right ones without exploding them?


texts:
I have a project being setup in my garden for an aeroponics system its basic components are:
1. Esp8266
2. Single channel relay board
3. Temperature & humidity sensor
4. 12v 3a - 100psi pump
5. 2 x 12v 12ah batteries

I now want to add a charger and solar panel to maintain the power on this system or atleast reduce charge frequency as much as practically possible.

My setup will be 30 seconds every 2 minutes the pump turns on, the pump is 36 watts I'm overestimating the rest of the system to say 2.5 watts so we are possibly looking at using 38.5 watts for 30 seconds every 2 minutes.

Now a 40 watt solar panel is incredibly expensive for what I'm using it for and I have looked at the 4.5 watt version but how do I work out the correct panel I need.

Is there a proper way to do this? I just calculated it will have the pump running for 3.4 hours in a 24 hour period.


texts:
I made a H bridge using 2 half drive like the picture

this works fine, but how can I disable the driver IR2110?
I'm afraid to put 0,0 in the input and that the driver will burn


texts: Will ARM replace that older processor architecture?

texts:
I know that those processors with ARM architecture have their advantages, but will it replace those old kind of ones? Or they just will be dealing with different kinds of applications and continue to live?

Edit: I am not seeking a fotrune teller. I just needed someone who knows it to describe what is going on right now? How does it seem to go?


texts: How do Ethernet controllers show activity with the LED indicator?

texts:
Ethernet controllers usually have an "activity" LED which blinks in some sort of correspondence with the packets traversing the port.

I'm wondering how the controller decides when to turn the LED on and off.  It's not a random or timed flashing when data is being transmitted - it is somehow linked to the data transmissions.  But the individual transmissions would likely happen much faster than our eyes could see (or at least it would look like extremely fast "blips" on the LED, or the LED would just appear to be illuminated solid).

How do these controllers convert the extremely fast pulses to something that resembles "activity" to our brains?

I remember seeing somewhere (some odd piece of hardware) that the indicator speed could be adjusted, but I can't remember where I saw that, or how it applied to the port.


texts: How does this button work without any circuit closing device?

texts:
This may be a stupid question, but I have searched online for a little bit and can't seem to find my answer. I am working on a circuit board that uses buttons that i've never seen before. These buttons just have a metal lead around them and an LED in the middle (for lighting up the button I'd assume) but how does a button like this even work? I've attached some pictures to show you what i mean.

this is the back of the push buttons from the device


texts: Workaround for the obsolete ATTINY15 1.5Mhz clock for FCC exemption?

texts:
The ATTINY15's was ideal for designing FCC Part 15 exempt battery powered products since its 1.6Mhz internal RC clock ran just below the 1.705Mhz cut-off.

The ATTINY2/4/85 replacement parts come with a 1.6Mhz compatibility mode, but this clock is derived by dividing an internal 6.4Mhz clock. Since the FCC exemption requires that the device "not generate or use frequencies above 1.705 MHz", this replacement part does not appear to be eligible for the exemption.

It does seem possible to qualify for the exemption by using the ATTINY2/4/85's internal 128KHz clock, but this is much, much slower and not practical for some applications.

With the ATTINY15 dead, are there any good ways to design Part 15 exempt battery powered products that need more horsepower than 128KHz, without needing to resort to adding an external oscillator?


texts:
I'm designing a device that needs to interact with smartphones and I need to choose between WiFi Direct and Bluetooth for communication. I don't need high speed, while a higher coverage would be good. I essentially need a serial communication and I already used RFCOMM with Bluetooth. Is it possibile with WiFi Direct or is it more complex?

What's the best choice looking to the future?


texts: programming atmega2560 by ISP on self-made PCB

texts:
For one of my project, I need an atmega2560.
So I made a PCB with the atmega2560 and ISP headers.
But I can't communicate with the atmega2560
There is also an external 16000Mhz oscillator.

Here is what I checked :

No short circuit
MOSI, MISO, SCK and RESET all have continuity from the header to the pins
The programmer used is an arduino Uno with the ISP Programmer sketch on it. (This arduino has been tested and is able to program another arduino uno via ISP)

Here is how everything is wired on the PCB. It's very minimalist : atmega2560, oscillator and two 22pf capacitors

What am I missing ?

I just have one VCC pin of the atmega2560 connected to VCC. Same for ground. Is this okay, or every VCC pin and every GND should be connected ?

Thank you in advance!


texts: Finding value of Resistance for Maximum Power

texts:
I am badly stuck in finding value for R in this circuit for maximum power transfer in the network,

It is my assignment question and I am badly confused.

Please help ,
Thanks.


texts: Can I use the 32.768 kHz output from a RTC instead of an external oscillator on a PIC MCU?

texts:
Using the 28 pin PIC18(L)F2X/4XK22 and a DS3231S real time clock. The MCU has input and output pins for an external secondary oscillator and the original schematic has no RTC, but an oscillator circuit attached to these pins.

Can I simply use the output from the RTC to feed the input of the MCU or is this an improper way? I will not be programming this setup, I am simply trying to add an RTC to an already crowded board and while I could fit it all the 32.768 kHz output from the RTC is temperature compensated and has a much better PPM tolerance.


texts: Power glitch when switching between voltage sources

texts:
I have I device with USB. When connected to USB it is powered from the USB port (an LDO to adjust from 5V to 3.3V), and when not connected to USB it is powered from a CR2032 battery. Below is the schematic with a P-MOSFET to switch between battery and USB power. The output from the LDO is 3.6 V, since it will drop slightly over D1.

simulate this circuit – Schematic created using CircuitLab

The problem I'm having is that on USB disconnect, there is a rapid drop in voltage. See the oscilloscope image below. When connected to USB the voltage is 3.28 V, and on USB disconnect the voltage rapidly drops to 2.1 V, before stabilizing at 2.5 V for approx. 60 ms before rising to battery voltage of 3.08 V. The duration at 2.5 V can be anything from 1 ms to, as in this case about 60-70 ms.

On a previous version of the device, the exact same components and schematic layout is used, just a different PCB/board layout. Below is an oscilloscope image for that version. The same behavior is observed, but the "in-between voltage" is 2.75 V instead of 2.5. The duration at 2.75 V can be anything from 1 ms to 60-70 ms in this case as well.

But how come the difference (2.5 V vs. 2.75 V) with the exact same components, just different board layout? And how do I go about fixing this problem? There are components in the device that does not survive (loses settings) when forced to run on 2.5 V for as long as 60 ms, and maybe the rapid drop to 2.1 V is a problem as well.

How do I fix this?

UPDATE:
The circuit load (across C1) is a low-power microcontroller, and some LEDs and buttons.

What I refer to as "USB disconnect", i.e. removing the USB power source and switching to battery power is accomplished through removing the device from the computer USB port. I.e., the LDO input disappears, and hence the LDO output 3.6 V.

ADDED:
Voltage drop on R1 (10K) when USB is disconnected:

Voltage drop on R1 (1K) when USB is disconnected:


texts: What do you call the cross-crossing network you see under a microscope?

texts: I'm self-studying computer architecture and digital logic design and have a question regarding integrated circuits. When you examine a chip up close, such as through a scanning electron microscope, you see a layered, criss-crossing network. Would these be what my book refers to as "supply rails?" They have diagrammatic illustrations but I'm not sure it's the same thing.


texts:
I want to find the amount of current that can be carried by a wire. The first step is checking out the AWG rating of the wire. It states 30AWG. Now, I checked out the table from this link - AWG link.

.

I see there are 2 columns that are related to currents - chassis and power. Which is the one that I must check ?


texts: Using an Arduino (Mega ADK), how do I blink an LED on a separate IC (ATMega328) using SPI?

texts:
I am attempting to learn how to control an ATMega328 IC from my ATMega2560 Arduino using SPI. I have found the various tutorials that use digital potentiometers, but I have no digital potentiometers and all I want to learn to do is blink an LED on the ATMega328 from the code running on ATMega2560 via SPI.

Can anyone please provide a few lines of code to show me how this is done?

Here is my pin configuration (using Arduino pin names for both ICs):

ATMega2560 pin 50 (MISO) => ATMega328 pin 12 (MISO)
ATMega2560 pin 51 (MOSI) => ATMega328 pin 11 (MOSI)
ATMega2560 pin 52 (SCK) => ATMega328 pin 13 (SCK)
ATMega2560 pin 2 => ATMega328 pin 10 (SS)
ATMega2560 5V pin => ATMega328 Vcc pin
ATMega2560 GND pin => ATMega328 GND pin
ATMega328 pin 3 => LED that I would like to blink

Here is my current code:

#include "SPI.h" // necessary library

int SLAVESELECT = 2;
int DATAOUT = 51;
int DATAIN = 50;
int SPICLOCK = 52;

void setup()
{
  pinMode(DATAOUT, OUTPUT);
  pinMode(DATAIN, INPUT);
  pinMode(SPICLOCK, OUTPUT);
  pinMode(SLAVESELECT, OUTPUT);

  SPI.begin(); // wake up the SPI bus.
  SPI.setBitOrder(MSBFIRST);
}

void setValue(int pin, int value)
{
  digitalWrite(SLAVESELECT, LOW);
  SPI.transfer(pin); // send command byte
  SPI.transfer(value); // send value (0~255)
  digitalWrite(SLAVESELECT, HIGH);
}

void loop()
{
  setValue(0x11,255);
  delay(1000);
  setValue(0x11,0);
  delay(1000);
}


texts: What kind of inductive load does a mains LED lamp present?

texts:
This follows on from another question I'd been asking.  Having been 'gifted' dozens of mains LED lamps, I've been blithely assuming that they don't offer much in the way of inductive load.

But, of course, they aren't just a mass of LEDs: there's a rectifier, and perhaps an inverter (though a glance at the wiring of the LEDs in my lamps suggests that there's two parallel chains of 65 LEDs, which would be about right to drop 230 V).

I've searched for information, but there's nothing that I've found.  Does anyone know a) if there is appreciable inductance in such lamps, and b) how one could set up a test rig to measure it?  thanks


texts: How to create a constant current source from a 12V,19AH Battery which is load independent?

texts: My intention of connecting a copper coil directly to Battery is to basically make the copper coil red hot to boil water. What I have observed is when I connect the 12V,19AH Battery to the 15mm thickness 50 turn copper coil, the Battery tends to drain quickly and the voltage shown by a multi-meter of the battery confirms the draining. On the other hand, when a 30V,10A Laboratory Power Supply is connected to the same coil, it gives a stable current of 9A at 9V, 10A at 10V and trips OFF above 10V. With 10A of current the heating of the coil achieved is fair enough that serves my purpose. How can I provide the coil a consistent of 10A of current which will also stop the draining of the Battery at such a fast rate which otherwise would had been greater than 100A?


texts: Use a Passive High Pass filter to filter out voltages from piezocrystal under a certain threshold

texts: I have a piezo crystal (SEN-10293, datasheet: 7BB-20-6L0) that I am using to detect if a person sits on a chair. The compression of the crystal generates enough voltage to wake up a microcontroller from sleep. This is done by connecting the crystal to a relevant GPIO pin set to wake the microcontroller when it is set to high. The problem is, the piezo crystal seems to be too sensitive, it will generate enough voltage to wake the microcontroller even when a person just moves around a little on the chair. My question is then, is there some way to reduce the sensitivity of the piezo crystal? I was searching around and came across Passive High Pass filter circuits which allow you to filter out frequencies below a certain threshold, but would this work for a piezo crystal, I am not super familiar with how voltages and frequencies relate to each other. Secondly, when a person gets off the chair the piezo instead produces a negative voltage, is there some way to invert this so I can use this to also wake the microcontroller, or is that not feasible?


texts: Buck, Boost..etc Is there always an IC for that?

texts:
First of all I am still in school so perhaps I have not been exposed to material that may answer this question for me.

I have recently become interested in power electronics. I have purchased a book on the subject and I am taking an online course.
Like usual they start with basic models where everything is ideal and as the course  goes on you begin to model losses.
I have breadboard a basic buck and it works great.
My question is that I feel a bit disillusioned because almost everything I learn "there's an IC for that"
I get the feeling that the fellas that design those IC are REAL engineers and everyone is just pluging and playing parts.

I understand the benefits of using an IC because it will reach an unparalleled level of efficiency versus discretes... but out there in the industry is there anyone making power converters not using a one size fits all IC? if so can anyone give some examples?

I have not taken a formal course on power electronics at school, so that fact contributes to my ignorance on the subject.


texts: A lot of places where I've read explanations about potentiometers either go into so much detail or they're so superficial that I don't understand the actual concept behind it. How would you easily explain to me what a potentiometer is and how it works?


texts:
can anyone please help me identify a datasheet for that CCD/CMOS sensor ? on the camera it says CCD but i highly doubt it since it's 4 dollars.
it's a reverse camera and i want to remove the overlay, tried to desolder the EEPROM and it just freezes and doesn't work.
EDIT : HERE IS THE EEPROM

https://anonymousfiles.io/owjwdNgk/


texts: 4 layer PCB stackup for motor control board suggestion

texts:
This is my first high power PCB. I have been doing some reading and going through few reference designs. really looking for some guidance from the community. Please do correct me and if possible point me at the right direction.
Lot of people has suggested for 70um or 2ounce copper. I personally want to avoid it if possible and use any existing PCB Stackup from JLC PCB 4 layer stackup with standard FR-4.
Also my stack up plan is to keep [1.SIG TOP| 2. GND | 3. POWER | 4. SIG BOT].n
The layout keeping the digital and analog grounds on the same ground plane with decent separation.
The board has to drive a 3 phase BLDC motor.

I was planning on keeping control board (TMC 4671) and the gate driver with power MOSFET on a separate board connected using a board to board connector. Should I do it on single board?
Usually design guides recommend lots of vias  while routing in between planes. for the power MOSFET. What is lot and how can I  calculate it?
I am using vias with 0.45mm diameter and 1.6mm height. I am not sure what should be the height should I assume board thickness from top layer to bottom here?
Should I use thermal relief vias for the MOSFET? If yes how  can i use and also where to decide to put thermal relief vias?
Planning for a 2mm trace with standard FR4 dielectric and minimum conductor space of 0.6-0.8mm. Is the conductor spacing and trace enough since 100A (assuming less than 5A continuous)?


texts:
I have tried many different op-amps in many configurations. But almost always I am getting a very unstable configurations:

https://youtube.com/watch?v=ybhDs-dw6j8

https://youtube.com/watch?v=O2C596rmJqg

The original signal is very stable.

Parameters I try to archive:

Bandwidth - 50 MHz
Slew Rate - 200-300 V/µs
Single supply if possible

Is it actually achievable? I know that the stability is much better in the dual supply configurations.

Some pictures:

The actual test circuit. .1u & 6.8u caps on +Vc.
I have tried many different resistors (from zero to 4.7k) on the feedback circuit and I am not getting any better results:

With small resistors it is a bit better on changing signals but it is much worse with the level ones. Larger are better for level ones but worse for faster changing ones.

I took this from the IC datasheet:

After many experiments this is the best waveform I have archived


texts: Connecting one circuit to another via a transistor as a switch

texts:
I'm a software engineer, and know very little about electronics. I'm learning slowly, so appreciate your patience and kindness :) I will gladly return the favour someday.

I'm trying to build a circuit to release the shutter of a DSLR from a raspberry pi. Releasing the shutter is as easy as closing a circuit, the circuit is entirely contained within the camera. So, I have a camera, with two wires from a disassembled shutter release cable sticking out of it. When I touch those two wires together, the shutter fires. Great, now to do it electronically.

The schematic on the left is what I prototyped using an LED and the on the right is the same (?, we'll get to that) connected to the camera in place of the LED. The LED scenario worked fine, which was exciting, the camera... did not, regardless of the value of R4 - I started with a resistor I believed to be correctly calculated (2.6MΩ) and worked down in resistance until I was using no resistor, the shutter never fired. I've tested all the components and swapped them around diligently checking they all work and are connected correctly.

There are two major differences I can think of, if you understand these and can help confirm and explain, that'd be great. If you spot something else that is the cause of my problems, that's great too.

I can think of:

1) The grounds on the RHS aren't actually the same, one is the camera and the other is the pi. So I'm essentially connecting two circuits via the transistor, whereas on the LHS, I used the pi's + and gnd pins to create power the LED circuit, meaning this is a common ground? Does this make a difference? What should I be doing to connect two circuits in such a way?

2) The current in the camera circuit is very low, 68μA, maybe this isn't enough to cross the transistor C to E (way out of my depth here :) )?
Details on the camera circuit can be found here: http://www.doc-diy.net/photo/eos_wired_remote/


texts: Compatibility between XBEE-PRO 900 HP and XBEE SX

texts:
I wanted to use a 900 MHz xbee and I need one side to be surface mount. So I'm thinking of getting an XBEE PRO 900 HP (XBP9B-DMST-002) and an XBEE SX (XB9X-DMUS-001). These devices have the same frequency and network topography but list different rf data rates [1]. Is it possible to get these device communicating with each other?
Thanks


texts: if transformer secondary remains open, and primary is excited by sinusoidal source will there be heating produced?

texts: If secondary coil of a transformer is left opened, and primary is excited by sinusoidal current source, will there be heating produced in the core of secondary ?


texts: Measure EMF Radiation from High Altitude Balloon

texts:
I'm participating in a competition which involves building a probe that will be attached to a weather balloon. It will probably rise up to an altitude of 30 km.
I am thinking of measuring EMF radiation with a frequency of ~1GHz. The idea is to determine how much activity there is on the ground (how many cell phones, wifi transmitters etc.). I don't need to extract any information from the signal, I just want to determine the "quantity" of wireless communication.
Due to the nature of the competition I have to deal with the following constraints:

The sensor may not cost more than 100$
The weight may not exceed 300 g
The device must either be small enough to fit into the isolated casing of the probe or be able to withstand temperatures of -40°C

Is it plausible to measure EMF radiation from such a distance? What sort of sensor should I be looking for?


texts: What FPGA chips support verilog-ams or verilog-a

texts: I am having trouble finding explicit evidence on any FPGA vendors website that their chip supports the verilog-ams and/or verilog-a. Do all these chips support it, or is it only "mixed-signal" chips, or something different entirely.


texts: Voltage regulation and current limiting with a microcontroller

texts:
I'd like to build a power supply for my desk. I've found a few projects based on the L200 adjustable voltage regulator.

In the example below, how could I replace R3 with a microcontroller, so that varying the current limit can be automated?

Likewise, how can R2/R1 be controlled?

Is there a better device for a task like this?


texts: How to increase current output of capacitor bank with buck booster?

texts:
I'm pretty novice when it comes to electronics given that my background is in mechanical engineering. But I am trying to design a circuit that can take a 5V (almost 0A current) to charge a capacitor bank, then have the capacitor discharge to power an Arduino. My Arduino circuit draws about 300mA at 5V for almost 30-40 seconds.
In my circuit, I am using a TPS61030 breakout board (Adafruit Powerboost 1000), which is capable of boosting a voltage as low as 1.8V to 5V and supposedly capable of outputting 1A of current. This works great and I can get a constant 5V for plenty of time by charging a 0.1F capacitor to 5V and letting it drain into the TPS61030. The problem is, I'm getting very little current, not nearly enough to power the Arduino for more than about 1 second. Can anyone suggest anything I can use to get the current I need? Again, I know very little about electronics and have a lot of learning to do - any leads would be appreciated!!
Thank you for your help.


texts: Need help to understand mechanical drawing for footprint

texts:
I am a new user of Altium Designer. I need to make a footprint of this varistor, and I cannot understand its drawing. Same thing happens for the rest of the components. Can someone here tell me how I am supposed to decide the pad diameter, height, width? Take this doc as a reference, and I hope I will cater other drawings as well then!

Here is the datasheet link (Littelfuse LA Varistor Series).


texts: Replacing the physical layer of MIL-STD-1553 with RS-485

texts:
I've been reading about MIL-STD-1553 buses, which very briefly are

multidrop
Manchester-encoded
1 Mbit/sec
32-station: a single "bus controller" master and multiple "bus terminals" slaves which speak only when spoken to

Given how similar the two buses are electrically ...

I was wondering if it's possible to replace the electrical layer with RS-485?

This is an engineering-curiosity question for an industrial application: don't worry, it's not in a fighter jet!

Wikipedia shows a 1553 slave responding to the master's transmit instruction like this:
 (source)

Is there any reason we couldn't do this pretty much exactly with an RS-485 transceiver?  [Edit for clarification] By which I mean replace all the 1533 transceivers, transformers and cables with RS-485 transceivers, cables, terminators, cutting at the red line of the diagram below.

A typical 1553 transceiver looks like this:

(from DDC-8553 datasheet)

It's not clear to me why the transceiver has differential connections to the the decoder and encoder (ie to the right), but I'm guessing it's for signal quality.

As far as I can tell, something like this with a classical 75176-format RS-485 transceiver should work identically as far as the interfaced device is concerned (assuming suitable RS-485 wiring, lengths, termination etc):

Any reason that wouldn't work?


texts: What timing constrains would I need to set for a handshake based clock transfer

texts:
I want to transfer a couple of bits between two clocks, so I build a small handshake logic, but my timing analyzer shows me some violations.
Setup/hold violations and in addition some rule check violations, about un-constrained asynchrous data transfer. I guess this is all related to some missing constrains.
I tried using multi-cycle constrains, but this didn't do much. (The clocks both use the same frequency so I assume this to be wrong anyway?)
The design, despite the violations works, but I still want to get rid of the / understand what's going on. Maybe someone here has experience in this field. When everything is derived from one common clock using a pll I never had such a problem, my first time working with a rather big fpga and multiple external clocks.
In case this helps:

Software Quartus PRO
FPGA Stratix 10
DE10PRO (Board from terrasic)

Edit:
The clocks should be unrelated and they are not derived from the same source (atleast not inside the fpga)
A bit more information:

(clk_sys) The first clock I get from a clock pin and change it using a pll inside the fpga (pll to make sure it has the same frequency as the following ones)
(clk_tx) This one is provided by a transceiver ip inside my fpga
(clk_rx) This one is provided by a transceiver ip inside my fpga

The transceiver uses an external reverence clock which is in turn generated by an external pll.
What I want to do is transfering the tx data from my user logic to my transceiver and the rx data from the transceiver to my user logic.
The whole design works more or less as a fast network card using fiber optics. (So there are even more clocks inside the design, like pci-e and even some ddr4 for logging purpose, but for the I used an avalon bus, which takes care of clock-crossing. Only for the transceiver I had to use user logic)
Finally:
Yes my question is how to transfer data safely between 2 clock domains without warnings from my timinanalyer.
As I have a handshake inbetween with multiple stages synchronisation register for the control signal I'm confident my transfered data is stable at the time. But my analyzer doesn't seem to recognize it (?).


texts: What exactly determines recovery time of Schottky diodes?

texts:
I see that low-voltage Schottky diodes have essentially zero recovery time. But would there not still be a small recovery time even for low-voltage Schottky diodes? If so, what determines recovery time there?

Some people say capacitance loading is the reason for some recovery time.

If this is true, what exactly is capacitance loading?


texts:
I've gotten interested in beam-forming via a phased antenna array. I read a few articles/tutorials and they have very  nice diagrams of antenna arrays and how the antennas interact to behind each antenna is the key piece: A phase shifter. And yet when searching for it it seems like more of a theoretical device rather than a physical one-yet really phased antenna arrays exist. What is it exactly? Is it something so simple it's just assumed I know what it is?

What, physically, is a phase shifter?


texts: How to select all components on Top layer in Altium PCB?

texts:
How can I select all components on Top layer of a multi-layer PCB in Altium without selecting the route traces?
And is there any way to select all components on both Top and Bottom layers together?


texts: What is OTP for selecting GPIO function in PMICs?

texts: I've been going through this datasheet and I don't understand what is meant by 'OTP' for selection the function of the GPIO pins. The function select table can be found on page 20. I'm also confused why it refers to inputs and ouputs as CMOS and NMOS. Can someone explain this?


texts: RF connector/ interconnect for Gate signals

texts: I need connector as shown in pictures. I spent good couple of hours trying to find them on Farnell but the lingo for such connectors is little difficult for me. I read a lot too but couldn't find those. Can anyone tell me what to search for?


texts:
We all know why using a properly compensated 10:1 probe is a must when viewing MHz-speed signals on a scope with a 1 MOhm input impedance. Now who can supply a good use for a 1:1 probe? These probes have not found much use in my lab.

The only thing I can think of is that the 1:1 probes might be useful for making measurements of power supply ripple, switching artifacts, etc. I, however, question whether the 1:1 probe is readily capable of a connection with low-enough ground transfer impedance to really see what's going on in, for example, a switching power supply rail. Howard Johnson ("Healthy Power") and Jim Williams ("Minimizing Switching Regulator Residue in Linear Regulator Outputs", page 11) both discuss a similar technique but use plain coax instead of a 1:1 probe. In Howard Johnson's example, the coax shield is then soldered to the board with bus wire to achieve the lowest possible ground transfer impedance. Eliminating inductance in the ground wire is key to probing the fast switching artifacts. I'm not sure how well a 1:1 probe would do in this case, but it can probably be made to work okay.

Can anyone recommend any other uses for the 1:1 probe??


texts: Motor is consuming less than rated current and more than rated power

texts:
I have a brushless DC motor of following specs.

I am using a roboteq controller to operated the motor. While running the motor i have collected the few params and here are the plots.

power curve - expressed in watt.

Current curve - expressed in amps.

Its running at 42 rad/sec (400 rpm). But i am not sure why the power is so high and current lower than rated. Can some one give a possible explaination also how can i increase current and reduce the power.

I am using a motor controller in a closed loop (small PID gains). As far as i understood, I only command the motor controller with the desired rmp. Based on the varying load ,i think the motor controller will vary the voltage(not constant) to stay close to the command rpm.  On top of the roboteq controller , I wrote a small piece of code to capture the current and power (can't capture how roboteq controller is varying the voltage).  Correct me if I am wrong.

I am new to the motor control, if you need more information kindly let me know.


texts: For a small Vin-Vout difference, is it worth using an LDO vs a buck regulator?

texts:
I want to step down 5V to 3.3V at around 250mA.

As far as I see it, there are two options to consider:

Buck: more space, higher cost
LDO: less space, lower cost, more difficult to remove heat(?), less efficient(?)

What I am wondering is will the LDO be more efficient and better at doing this job? I've heard things like 6V to 5V solutions usually use LDO's instead of buck regulators because they are more efficient, but I'm wondering if this works for 5V to 3.3V?


texts: Do I need bypass diodes when Vout is higher than Vin for an RTC?

texts:
tl;dr:  I need 3.3v at all times, but it clashes with a secondary switched on/off 3.3v I also need.  How can I address Vout being higher than Vin, without feeding voltage back into Vin when I don't want it there?

I'm working on a project that is battery powered with two 18650's.  It requires an RTC that is built into the uController I am using (Sparkfun's Artemis).
This means I need to always supply 3.3v to the Artemis.
So I have my "switched on/of" portion of the circuit, battery -> load switch -> 5v reg. -> 3.3v reg.

It's probably important to also note that there are other powered components after the load switch, beyond the 5v & 3.3v regulators.

Then I have an extra low power 3.3v regulator that is not switched, for the RTC...   so, battery -> 3.3v (The artemis can deep sleep on the order of 10's of uAmps)
This means that when I want the system to be powered "off", the uController will always have 3.3v in it because the uController needs power for its RTC, even if minimal.
Does it make sense to do something like in the following picture, to the 3.3v regulator on the switched rail?

I could do this instead,

but then 3.3v will exist in my "switched on/off" power rail, when off, which doesn't sound ideal because of a few other IC's that may be in a brown state because of that (I.E. a high voltage power controller)

What is a good way to tackle this design challenge?
Thank you for any help you can provide! It's tremendously appreciated.

  Small note..  I do have battery protection circuitry, so if the
  battery voltage falls below 6 volts, a high-side mosfet will shutoff,
  at which point I don't mind losing power to the RTC.  My load switch
  shuts off power when it gets near this threshold, but just not to the
  low power 3.3v regulator.

Edit:  Upon further investigation, I think the key term I was looking for is "reverse current & reverse voltage protection" in my parts search.  I didn't realize this was a feature for some power regulators. An example being, https://www.ti.com/store/ti/en/p/product/?p=TL1963A-33DCQT

Awesome!  :)


texts:
This is the adapter i got in My hand

I need a cheap diy stable circuit for making an Adjustable PSU using LM317 Voltage Regulator. I got a adapter with output power supply of DC 30v 400mA. I need a circuit can  do both  variable voltage and variable amps. Lets say the voltage between (1-30 volts) and Amps between (10 mA-5 A)

Thank you!


texts:
I'm trying to understand how to drive a servo that needs 5V power with a 3.3V output microcontroller. If I have a 3.3V PWM signal and a 5 V power source, is there a way that I can use a single N-Channel MOSFET to control the servo's motion?
Thanks


texts:
I'm learning electronics and found this question below, which is exactly what I've been questioning myself. But there was no good answer there, so maybe someone here can help.

Original question:

  Suppose you have a 9 V battery that you connect to a load having a
  very low resistance (e.g. 0.1 ohm). From Ohm's law, the current would
  be I = V/R = 90 amps, which seems impossible to obtain from such a
  battery. If we suppose that the load will not burn, which of these
  options is the correct one?

  1) The battery has a maximum power it can
  provide. For example, if this power is P = 100 W, then since P = RI^2
  the current will be I = (P/R)^0.5 = 31.6 amps and the voltage V = RI =
  3.16 V.

  2) The battery has a maximum current it can provide. For example, if this current is I = 5 A, then V = RI = 0.5 V. I am aware
  the values given for P and I might not be realist.

  I am just
  interested in the general behaviour of a battery (is current, power or
  voltage the fixed value?). Thanks for your help.

Source: https://www.physicsforums.com/threads/maximum-power-current-for-a-battery.96159/

So far I've read datasheets for some batteries and found some intriguing data about how a battery behaves, given certain circumstances such as temperature, load (current discharge), and average voltage.

Beyond these factors, I'm trying to understand if there's a definitive quantification of the total "energy" of a battery? Since mAh, Wh and Joules seems to vary depending how the discharge occurs.

For example, this datasheet from energizer shows that the mAh capacity changes as a function of the discharge rate. If that's the case, is the 'total cell energy' varying?

Thank you.


texts: For embedded code, why should I use "uint_t" types instead of "unsigned int"?

texts:
I am writing an application in c for an STM32F105, using gcc.

In the past (with simpler projects), I have always defined variables as char, int, unsigned int, and so on.

I see that it is common to use the types defined in stdint.h, such as int8_t, uint8_t, uint32_t, etc.  This it true in multiple API's that I am using, and also in the ARM CMSIS library from ST.

I believe that I understand why we should do so; to allow the compiler to better optimize memory space.  I expect there may be additional reasons.

However, because of c's integer promotion rules, I keep running up against conversion warnings any time I try to add two values, do a bitwise operation, etc.  The warning reads something like conversion to 'uint16_t' from 'int' may alter its value [-Wconversion].  The issue is discussed here and here.

It doesn't happen when using variables declared as int or unsigned int.

To give a couple of examples, given this:

uint16_t value16;
uint8_t value8;

I would have to change this:

value16 <<= 8;
value8 += 2;

to this:

value16 = (uint16_t)(value16 << 8);
value8 = (uint8_t)(value8 + 2);

It's ugly, but I can do it if necessary.  Here are my questions:

Is there a case where the conversion from unsigned to signed and back to unsigned will make the result incorrect?
Are there any other big reasons for/against using the stdint.h integer types?

Based on the answers I'm receiving, it looks like the stdint.h types are generally preferred, even though c converts uint to int and back.  This leads to a bigger question:

I can prevent the compiler warnings by using typecasting (e.g. value16 = (uint16_t)(value16 << 8);).  Am I just hiding the problem?  Is there a better way to go about it?


texts: The PWM output of dsPIC chip fail to drive the motor with H-bridge circuit

texts:
I am simulating a dsPIC33FJ32MC202 in Proteus to control a motor.

I used an H-bridge to let motor rotate, but the motor is not rotating after the simulation started.

You can see the oscilloscope output connected to the IO pins of the dsPIC. The ideal output should be 3.3V to -3.3V, I don't quite understand why it is 2.3V to -2.3V, but it seems OK.

And also the oscilloscope output connected to the lines between Q3-R1 and Q1-R3. The output looks weird, and I don't know the reason causing this phenomenon.

P.S. You can download the Proteus design file and my program files(.c and .hex files) here.


texts: Can you use a 5 input NAND gate as a 4 input one?

texts:
I have a circuit that has 4 inputs and am only allowed to use 5-, 3- and 2-input  NAND gates. Yes this is an assignment question but I have already solved the design of the circuit.

I just don't know how to use (if possible) 4 outputs with a 5-input NAND gate.


texts:
I want to boot an ARM Linux board (Allwinner H3 for example) from a generic (micro) SD card through an SPI interface. Can an SD card accept SPI communication right away or is there any "SPI mode initialization" needed on the card?

I must admit I have not gone through all the SD documentation and examples available (like linked in this answer) as I am not on such a low level like Arduino but on a Linux system instead.

This post says an SD card needs to be "switched" to SPI mode first and I am not sure how this is compatible with the SPI boot process in Linux. Can someone explain please?

Edit: The reason for booting from SPI on a Linux board that has a micro SD card slot is that I want to use this slot as a secondary removable storage only (for saving photos etc.) and want to have a system on different SD card that will be directly soldered to the SPI interface (possibly without intermediate board/controller).


texts:
If a transformer has efficiency of 96%. It means for a 500W capacity and load, the input would be 520W, output 500W so 20W would be emitted as heat.  If load is 250W, then input would be 260W and 10 watts would be emitted as heat.

But if there is no load (zero load), how do you compute the wattage that would be lost as heat during the initial stage when magnetic field and flux is being built with no load on the secondary? Is it more than the inefficient percentage lost with load?

I'm computing sealed enclosure heat transfer for a design I'm having and I need to know the above.


texts:
I am new to electronics and since I am studying computer engineering (4th semester right now) I am not that familiar with analog electronics.
I have a small project that I want to implement mostly in my free-time which includes a small boombox controlled by STM32 NUCLEO F446RE. Right now I am trying to design the power supply. I am going to post a screenshot along with the files for EAGLE.
Input voltage is 230 V 50 Hz.
Regulator datasheet
I want to achieve a 10 V output voltage in order to supply the NUCLEO F446RE and the TAS6424L-Q1 amplifier.
I will give you both eagle and circuit lab schematic.

simulate this circuit – Schematic created using CircuitLab


texts: Please help understand how a household electrical component works in context of step down voltage and ampere?

texts:
I will try to ask as intelligibly as possible, please bear with me.
I understood that P = VI which is the power to be transmitted, and V = IR is a voltage loss which must be overcome by transmitting at high voltage and low current.
Now, a transformer works on the principle that it transforms power (ideally with no loss) from one circuit to another. So, a circuit with 10000V and xA will convert to 230V and yA, to retain the same amount of power transmitted.
The real questions:
1] How do two different rated components work from the same line? Eg a 100W bulb and a 40W fluorescent tube?
2] A mobile phone charger uses only 5V and provides a low current to charge the phone. But it has a transformer to step down the voltage from 230V to 5V. Does that not increase the current as per P = VI and transformer principle V1I1 = V2I2?
3] With the understanding that somehow the current passing is decreased as well as the voltage in a mobile charger, where does the extra power go if it is not transmitted to the phone?


texts:
I have an RFID antenna that seems to be on a custom PCB. The issue I have is that the antenna on one side works fine, but the other side does not. I'm not sure if it is even possible or worthwhile to troubleshoot and try to repair the antenna. I would have first resorted to buying another one, but a vendor charges ~$350 for the unit since I guess it's niche... There isn't really a model number of the antenna and is used in a 3D printer to detect the material cartridge. Could a trace be cut somewhere or are there other obvious things to check/test?

Any help and advice is greatly appreciated, thanks.


texts: Can polarized capacitors be used for negative voltage generation?

texts:
simulate this circuit – Schematic created using CircuitLab

I want to use this circuit for charging, discharging and creating negative voltages off capacitors for a special application.

I will then charge this capacitor series by its negative terminal.

This circuit looks very vell for ceramic capacitors but my question is if it would perform the same for electrolytic polarized capacitors? Since I will be charging the negative voltage capacitors again by the capacitor's negative terminal, I don't know if I should charge those polarized capacitors by the negative terminal.


texts: Carrier generation at receiver in DSB-SC modulation?

texts:
As shown in fig., In this scheme input signal is square and passed through a narrow(high Q) bandpass filter tuned to \$ w_c\$.Finally the ouput comes to be a sinusoid of frequency  \$ w_c\$.

But to implement this scheme you need prior information of \$ w_c\$ because you need to tuned your bandpass filter at \$ w_c\$.

My question is that if you know \$ w_c\$ then why not just use a crystal oscillator to generate carrier of same. why use all PLL, filters etc. ?


texts:
I am making a project using at89c51. I used my mobile charger (output: 5V, 1A)
 as the power supply. Will my IC get damaged due to the high current?

I asked cause, without loading the program I connected the pin40(Vcc) and pin20(gnd) just to check whether all the port pins except port0 give output 1 or not, which is as I believe by default. And I got haphazard values which changed everytime I turned the supply off and on.

I also couldn't find the supply current range in the datasheet so got more confused.

Please advise.


texts: How to use CR2032 button cells for excitation of load cell

texts:
I am using a load cell that required 9-12V excitation voltage. Can I use a few, say 4 CR2032 button cells to generate 4x3V=12V of excitation voltage for the load cell?

I could also use a 9V batter. But my problem is that the battery goes down and that affects the accuracy of the load cell output.


texts:
So,here's the equation of Mass-Action Law:-

\$ np =n_i^2 \$

Here, \$ n= \$ Electron Charge Density ; \$ p= \$ Hole Charge Density
And, \$ n_i^2= \$ Intrinsic Charge Carrier Concentration

The equation is true for both intrinsic and extrinsic semiconductors and tells 2 important facts about extrinsic semiconductors:-

For n-type semiconductor, \$ n>n_i \$ so \$ p<n_i \$
For p- type semiconductor, \$ p>n_i \$ so \$ n<n_i \$

My book says that

"If a pure semiconductor is doped with n-type impurities, the number of electrons in the conduction band increases above a level and the number of holes decreases below a level. Similarly, the addition of p-type impurities to a pure semiconductor increases the number of holes in the valence band above a level and decreases the number of electrons in the conduction band below a level."

The question is:-

Suppose we have an intrinsic semiconductor. It is known that, in a intrinsic semiconductor, \$ n=p=n_i \$
It is doped and  turned into a n-type semicondctor.

My book says the number of holes in valence band/hole density, \$p\$ decreases. My question is that does the hole density (minority charge carriers) in n-type semiconductor decreases only due to recombination process or is there any other reason other than the recombination process?

Why has the question arisen in my mind?

See, in n-type semiconductor, holes can be generated by using thermal excitation only.

Now, if in the intrinsic semiconductor(sc), the hole density is \$ p \$ (which can be produced only by thermal agitation) and then that intrinsic sc is changed to n-type sc, the hole density, \$ p \$ will not change but the electron density \$ n \$ will increase by large amount(\$ n>>>p \$) due to the presence of pentavalent impurity atoms and due to thermal agitation.

So the only way left with which the hole density, \$ p \$ can decrease is the process of recombination.

 A way to Describe the Decrease in Hole Density other than Recombination Process in n-type semiconductor(According to Me):-

Suppose a crystal of intrinsic sc having 10 atoms(not possible but assume). 4 out of 10 atoms gets thermally excited and thus, 4 electron-hole pairs are created(\$n=4;p=4\$).
It is turned into a n-type semiconductor by doping it with 2 pentavalent impurity atoms. The 2 impurity atoms replaces the 2 host atoms so to maintain the total number of atoms, i.e., 10.

One of the 2 pentavalent impurity atoms replaces that host atom which was earlier generating an electron-hole pair. So,now,

Electron-Hole pairs generated due to thermal excitation=3
Electrons generated due to pentavalent impurity atoms=2

Thus, \$ n=3+2=5 ; p=3 \$
So, hole density decreases from 4 to 3

So, while doping, if pentavalent impurity atoms replaces host atoms which were earlier creating electron-hole pairs, then there will be decrease in the value of hole density in n-type sc.
And that's how, the hole density can be reduced other than recombination process.

But the whole hypothesis is just based on the probability of replacement of thermally excited host atoms with donor atoms.

The hypothesis given most probably is wrong. But that's how I am visualising it.

But my main question is why the hole density in n-type semiconductor decreases and electron density in p-type semiconductor decreases? Is the recombination the main cause or something else?

Note:-
Please, bear with me. I am studying introductory electronics.


texts: What does RADOM stand for in this datasheet?

texts:
I found the following sentence in the datasheet of a FMCW module:

FMCW ramp is visible at the outputs caused by self-mixing effects, near objects and cover (RADOM).

My search results are flooded with information about the city Radom and the firearm. Is it something like a term for a collection of radar obstructing materials?

EDIT:

I see the suggestion RADOM standing for radome as both a comment and as answer. However, I wouldn't expect capitals if they mean radome. Is there any reference to these two being one and the same?

The context suggests RADOM being some kind of obstruction. As far as I know, radome polymers don't count as obstruction (that's why they're radome, invisible to radar).


texts: Are devices damaged by high current, or high temperature?

texts: I'm wondering if electrical devices are damaged by the current or by the temperature. Imagine we have a little device with a maximum input current of 500mA. I'm sure that if we subject it to 1A or 4A it will become very hot and probably explode. The question I'm asking is whether the high temperature induced by the current is the principal cause or it's the high amount of current that is the cause. I'm wondering if we cooled the device at -230 Celsius (we're accepting that it's still working) and then we applied that high amount of current would it survive?


texts:
A solid state relay specifies a trigger current of "7.5mA/12V". How much current does it draw at 5V?

This is the relay. I'm controlling it with an Arduino which has a maximum current draw of 40 mA per pin. Am I correct in calculating it multiplying 7.5 by 12 then dividing by 5 (the new voltage)? That gives me 18 mA, well within the limits of the Arduino pin - is it really that simple, or am I missing something important?


texts: What is a fast built in op-amp to use in OrCAD Pspice Capture? Or how can I design one?

texts:
I am trying to simulate a 100 kHz FitzHugh-Nagumo oscillator in OrCAD Pspice capture (this paper gives the motivation for the configuration, but is for a 180 Hz oscillator, https://ieeexplore.ieee.org/abstract/document/6313098). I have built this oscillator and have the differential equations, but we are trying to troubleshoot some discrepancies between experiment and simulation at a high level. The ODEs look okay for an individual oscillator, so I want to reproduce a single oscillator in PSpice. We are using a fancy op-amp with a 50MHz bandwidth, AD844 (datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/AD844.pdf) which does not appear as a simulate-able component in Pspice.

I am not an electrical engineer, so please humor me with what I hope are reasonable questions. I am pretty new to PSpice as well.

First question: what is another high bandwidth op-amp that does appear in Pspice? I have been hunting for an hour and I'm not getting any closer.

Second: if there isn't a suitable built in op amp, is there a way I can enter values from the datasheet into a generic op-amp shell? There appears to be this kind of a method for Multisim, but I can't find this interface for OrCAD Pspice.

My FHN: C1=13 nF, R3=100 Ohm, R1=110 Ohm, R2=100 kOhm, L1=100 uH.

Edit: I should comment that we are using AD844 rather than LM358, a more normal 1.2 MHz bandwidth op-amp, because the LM358 doesn't seem to support oscillation. I don't know why that is--I wouldn't be surprised if the LM358 clipped the waveform a bit, but it doesn't move at all. This is a separate mystery that I also welcome commentary on.


texts: What are the advantages of CPW over microstrip?

texts:
I have to use a coplanar waveguide (CPW) for a project which is going to characterise small amounts of tissue.  I have never used CPW before.

What are the advantages of using CPW?  What would be some key words for searches to get me started and help me understand more?


texts: Best way to manage multiple 12V inputs and outputs from Arduino?

texts:
For a bowling alley I am going to make a circuit using an Arduino Mega to turn on arrow lights(1-4 bulbs in each) given the bowling pin lights that are lit up at the moment on a masking unit. AMF no longer makes the board that originally did this internal to the pinspotter chassis. All of these lights are 67 bulbs(BA15S base, 12V). Here is a draw-up of the plug from the chassis that lights up the pin lights:

How these pin lights are wired is that the 12V(Pin 29) is wired in parallel to all of the lights and then to turn on that pin light, the chassis grounds out the specific pin(14-23) that the other end of the pin light is wired to:
My question is, what is the best way to go about getting 5V inputs from these lights and then controlling 12V to power the arrow bulbs?
What I am thinking for the inputs is using opto-isolators. Here is an example of knowing when bowling pin 1(Pin 18 on the plug) is on/grounded:

For the outputs, there are 11 arrows in total for each lane. I was thinking of using relays, with the 12VDC(Pin 29) going to the common and then the NC and NO would go to the bulbs for each arrow, then going to the Ground on the plug(Pin 2).
Is there a better way about doing this? I looked at the patent for the board AMF used to make and it shown they used NOR Gates, optical couplers, a ROM/PROM for determining the arrow, and a decoder. I don't have much knowledge about ROMs or PROMs.
Edit: I am planning on using IRLZ44NPBF or STP16NF06L MOSFETs, will these be good enough for switching 12V at most around 1.2A(for the arrow which has 4 bulbs in it, the rest would have lower current)?


texts: Why are power supplies almost always made using through hole components? Every computer PSU I've taken apart uses through hole components, though occasionally (not in all cases) surface mount components are found on the bottom. Don't these have to be hand assembled? (before reflow or wave soldering) If so, why are they still doing this, even though labour costs are low in China, it still must cost less for a machine to pick and place SMT stuff... or am I missing something?


texts: BJT Current limiter for linear power supply

texts:
I am trying to design a current limiter or my LM317 based power supply using this schema.

The power supply must be able to provide a maximum of 1.5A@30V.
I made some calculations and I would like to understand if I am on the right way.
Goal is to find suitable values for the resistors and the right BJTs.

1) Q1:
Assuming the power supply is working at its limit, on Q1 we will have a Ic=1.5A and Vce=Vcc-Vq2be=30-0.7=29.3V.
A suitable BJT able to support this values could be the D44H8.

2) Value of R1:
The D44H8 has a worst case current gain of 10. So, on Q1, if Ic=1.5A the Ib=1.5/10=0.15A. Being near the limit of 1.5A, we can assume Vq2be=VRsen=0.7V, thus: VR1 = 30-0.7-0.7=28.6. This lead to R1 = 28.6/0.15=190 Ohm

3) Value of Rsen:
On Q1: Ic=1.5, Ib= 0.15, Ie=1.65
Voltage drop across Rsen is circa 0.7. Then: Rsen=0.7/1.65=0.42 Ohm

4) Q2:
Q2 must be able to support at least 30-0.7-0.7=28.6V on its collector, but much smaller current. I choose a BJT in the BC337 family, which will guarantee 45Vce and a max collector current of 800mA

Keeping R1 constant and varying Rsen I can set different maximum current values on the load.

Am I more or less right?

simulate this circuit – Schematic created using CircuitLab


texts: Circuit to convert negative voltages to MCU / FPGA

texts:
I am trying to connect a tacho that is fitted on a DC motor to an MCU / FPGA. It is being used to provide speed feedback of the DC motor.
At full speed the tacho generates around 5.5Vdc which is converted with an ADC before being connected to the MCU / FPGA. As this task requires the motor to go in both directions the tacho also generates negative voltages.
If the voltage was negative only it is easy to convert it with an inverting op amp setup.
Is there a circuit that can convert the 0 to -5.5Vdc to an equivalent positive voltage and leave the positive generated voltage unchanged?


texts: Overdrive Voltage Effect on Cascode Operation

texts:
Working on this exercise:

I understand that if all the transistors in a cascode have the same current and the same Vgs then they will have the same Vov. However in this case the Vgs do not seem to be the same and so I'm wondering how all Q's have the same Vov. Additionally, if all Q's have a Vov of 0.2 V then shouldn't the possible range of output voltages be this?:

*Side note, when I initially tried the question I used Vds=Vov and worked from the top and bottom to get Vovs of Q1 = Q4 = 0.2 V and Q2 = Q3 = 0.3 V, which give the output voltage range given in the answers of the book.


texts: What's the difference between an infra-red and a normal phototransistor?

texts:
I was wondering if there is any difference between an infra-red phototransistor and a normal phototransistor.

I was also wondering if either of these would be directly compatible with an Arduino?

For example, I'm looking at this phototransistor. It's for a line follow robot.


texts: Turning on an LED based on light and darkness?

texts:
I know this question has been asked a lot of times and there are a lot of tutorials but please bare with me for one second. I understand the basic concept but based on my simulated results, one thing is not matching my expectation. Please see circuit below.

I expect that when I increase the base voltage very high, the collector voltage will decrease to 0, as it does. But why doesn't this put the transistor into cutoff/saturation? Why doesn't the current decrease to zero? No matter what Vbe is, all Vce curves go to zero.

Here is a link to the VCE curve:
https://www.st-andrews.ac.uk/~www_pa/Scots_Guide/info/comp/active/BiPolar/bpcur.html

[EDIT] Also, note that the 2N3904 has a saturation collector-emitter voltage of 0.2. So really, as soon as the voltage decreases below 0.2, it should decrease.


texts:
I'm using the MMA8453Q for tilt detection of 45 degree in any axis. I'm a newbie to embedded devices. I have a few questions.

1) Should I be using Transient detection or Motion detection for my use case? I referred the Application note AN4071. But, I'm unable to understand the use case scenario for both transient detection & motion detection with respect to tilt detection.

2) I'm currently using Transient detection. But, it is detecting only abrupt shakes. When I turn it slowly, it doesn't detect the tilt even if the board is in 90 degree. Is there any specific reason for that?

Register configurations are:

CTRL_REG1 - 0x1A  (100 Hz ODR & F_READ)
XYZ_DATA_CFG - 0x00 (2g)
HP_FILTER_CUTOFF - 0x01 (2 Hz)
TRANSIENT_CFG - 0x1E (Enabling all axes & latch)
TRANSIENT_THS - 0x0B (For approx 45 degree tilt)
TRANSIENT_COUNT - 0x05 (50 ms debounce count for 100 Hz ODR)

Kindly suggest me which registers I should change to detect if I move the board really slowly. Any kind of related suggestions or explanations are much appreciated.

EDIT:

I tried reducing the cut-off frequency. But, I couldn't reduce it below 2 Hz, as it started detecting interrupts even when it is stationary.


texts:
This is a very classic problem
I am working on a buck converter using LTC7803 to charge a battery but to do that i need to make a relation of battery & Buck voltage for the feedback voltage (Vfb).
For example:
Battery range: 0.5v to 4.2v
Buck charging range: 1v to 4.7v (0.5v offset)
Vfb pin changes output between 0(max output) to 2.0v (cut off)
my goal is to design the control using op amps, if someone can help me design its control, i will be very grateful.
I will control the current and charging time by myself, just need help in designing control using op amps.


texts: Quartus/SignalTap: Is there an equivalent to Xilinx's ICON, VIO, ILA IP-Cores in Altera's SignalTap?

texts:
Xilinx offers an Integrated Logic Analyzer (ILA) / called ChipScope. Altera's Quartus II comes with SignalTap - an equivalent solution.

As an advance user\$^1\$, I'm using ChipScope as pre-compiled netlists. These *.xco and *.ngc files are generated via CoreGen and embedded into the design hierarchy by VHDL entity instances.

I would like to equip a Quartus II example project in the same way:

configure analyzer cores
compile them to a netlist
embed them into the design and connect the analyzer ports to my list of observable signals
provide a default SignalTap configuration file

Question:
Is there an equivalent to Xilinx's ICON, VIO, ILA IP-Cores in Altera's SignalTap?

Appendix:

Here are the Xilinx steps compared to list:

Configure an ILA core in CORE generator (=> *.xco file)
While saving the*.xco file, it's compile to a netlist (*.ngc, *.ncf, ...)
A wrapper *.vhdl file is provided, which is replace by the netlist in the translate step
each ILA provides a *.cdc file, which can be imported into the ChipScope project to load the signal names

\$^1\$ Pre-compiled ILAs save synthesis time; can be configured with complex cross-triggers; can be used with VIOs (Virtual-Input-Output cores).


texts: Overvoltage protection for low side MOSFET using TVS or Zener

texts:
For the following overvoltage scheme taken from this document, it appears that a zener diode is used to turn the gate of the MOSFET on when the drain voltage exceeds a certain value. For this protection scheme, does it make a difference if a zener diode or transient voltage suppression diode is used?
Note: There is a pulldown resistor between the gate and source.


texts: How does this circuit work? (AM receiver)

texts:
I do not completely understand how this circuit works:

First, I do not understand how the LC filter selects the frequency. I know that it's impedance is 'infinity' at the resonant frequency, but I don't understand how it rejects the other frequencies: no matter the impedance of the LC filter for a given frequency, the voltage is applied at the 'X' node and hence every frequency is applied at the input of the diode.

I do not understand the concept of 'shunting a signal to ground.'

Second, I do not understand how the R1/C2 network works.

It is said that its purpose is to 'smooth' the input signal in order to get only its envelope at the amplifier input. How does it work? Because the output signal of the diode (the AM signal of the selected frequency) is directly applied at the input of the amplifier, so I don't see how the R1/C2 network can smooth anything.


texts:
I'm trying to do the following let's say bit extension in a generic way.

First Considering B signal with an even number of bits (NBITS). here is an example:

B = 10100011

Second, adding a zero bit to LSB

B1 = 101000110

Finally, By doing an extension I mean repeating even indexed bits (Bold ones) except for the LSB (0) and MSB ones as:

V= 101 100 001 110

I tried this but it's not working:

process(B1)
variable j: integer :=0;
begin
  for I in 0 to (NBITS-2) loop
    if (I mod 2)=0 then
      j:=j+3;
      S(j-1 downto j-3) <= B1(I+2 downto I);
   end if;
end loop;
end process;

I appreciate any help...

EDIT:

Consider NBITS=8 as the given example, I get this error during simulation, While clearly i'm not reaching to 14 for varaible j!

# ** Fatal: (vsim-3734) Index value 14 is out of range 11 downto 0.
#    Time: 0 ps  Iteration: 1  Process: /tb_booth_encoder/t1/line__37 File: /home/ms20.58/LAB02/P4ADDER/vhdlsim/BOOTH_ENCODER.vhd
# Fatal error in ForLoop loop at /home/ms20.58/LAB02/P4ADDER/vhdlsim/BOOTH_ENCODER.vhd line 43
#

EDIT

Here is the full code:

LIBRARY IEEE;
USE IEEE.std_logic_1164.ALL;
---------
entity BOOTH_ENCODER is
    generic (NBITS :integer := 8
        );

    Port (
        B:        In        std_logic_vector(NBITS-1 downto 0) ;
        S:        Out        std_logic_vector((3*(NBITS/2)-1) downto 0));
end BOOTH_ENCODER;

---------
architecture BOOTH_ENCODER_BEHAVIORAL of BOOTH_ENCODER is

signal B1: std_logic_vector(NBITS downto 0);  --Input with extra 0 at LSB

begin

B1 <= B & '0'; --Extension of bit for encoding

process(B1)
variable j: integer :=0;
begin
    for I in 0 to (NBITS-2) loop
        if (I mod 2)=0 then
            j:=j+3;
            S(j-1 downto j-3) <= B1(I+2 downto I);
        end if;
    end loop;
end process;

end BOOTH_ENCODER_BEHAVIORAL;
```


texts:
I would like to control the tension of a string attached to the armature of a DC motor. I think the StackExchange thread here does not fully answer my question. Here the schematic (pencil sketch) of a test rig that I have in mind.

Essentially there is a DC motor that is controlled by some drive electronics which enables the motor to provide a certain torque at the motor's shaft. The drive electronics is driven by a high power switched mode bench-top 24 V power supply. The string is attached to the shaft (without slip) of the motor. The string is then routed through a pulley coupled to a load cell, and then secured to an immovable wall. So, the torque applied by the motor linearly correlated to the tension on the string since Torque = moment_arm x Force

My question is in multiple parts:

I understand that torque control is performed by altering the armature current. I also understand that this can be done using a PWM DC brush motor driver. But, I am working on a wire-driven robot and need the motor to be backdrivable (essentially if I pull the string with a tension greater than the tension on the string, it should safely allow the motor to turn backwards against the torque that it produces). Doesn't this mean that there will be a large back EMF when we backdrive the motor by pulling on a string with a tension greater than that produced by the motor?
Does this mean mean a switched mode power supply will be ruined by the back EMF and does this eliminate the use of PWM voltage control?
What electronic drive circuit will allow me to do this safely without the worry of brown-outs or circuits failing?
It is decidedly easy to deduce that the the tension on the string given the mounting orientation of the load cell. Does it make sense to build a PI controller to maintain a reference force by using the PWM drive circuit mentioned above?

EDIT: I was afraid of being too verbose with my question, but I am adding more information below as requested:

For context, I am building a wire-driven robot using motors to simulate muscles. Muscles typically don't have speeds over 500 mm/s. This means that in my sketch, the wire can be wound fast enough to account for this. Assuming a shaft with 3 mm radius and one wire thick winding only,that results in a max rotational velocity of 1591.5494 RPM (or 26.5258 RPS). I don't need the motors to run at stall torque, but I need is the ability to run the motor to pull the wire with varying torques while achieving a maximum of 1592 RPM which is well within the range of the motor that I use (I don't need specific speed control though - it is fine if I can run at 1592 RPM at all times).


texts: Buck/Boost converter TPS63070RNMT is not working properly

texts:
I am working on a Buck/Boost converter design which is based on Buck/Boost converter TPS63070RNMT. Below is the schematic design. All the selected components are as per the Section 9 of the datasheet.

U6 is powered by either USB (5V) or a rechargeable battery (2.8V-4.2V) as shown in the Schematic below. Expected Output is +3.3V/2A.

USB connection is given priority in the design. If both USB & battery are connected to the board, PCB will be powered on by USB while battery gets charged.

The issue I am facing upon powering up is U6 not working as expected. Output is approx 1.2V and there is a lot of humming sound coming out of inductor. U6 is getting heat up very quickly. It is also affecting Original input waveformsand other sections. For example, USB input = 5V DC is superimposed with square wave. VBATT net on U1 also has some distortion in the form of sawtooth signal.

I am suspecting the inductor saturation issue. Did anyone face similar issue earlier?

Below is the layout of 3.3V supply section. It is as per the recommended layout mentioned in datasheet.
Copper pouring added for VIN, Inductor nets and 3.3V. There is a 3.3V copper plane on Layer 3. On TOP layer, whole section is surrounded by Ground copper.

Need some inputs from the expert.

Thanks in advance.


texts:
could you help me to find the band-pass gain of the following filter please?

The correct expression of pass-band gain hasn't the term \$ C_{B}R_{B} \$ to the numerator (said my professor), instead in my expression there is:

$$G_{PB}=\left(1+\frac {R_{4}}{R_{3}} \right)\left( 1+\frac {R_{2}}{R_{1}} \right)R_{B}C_{B}$$

Thank you for your help.


texts: Multiple switching LED drivers on single PCB

texts:
I am working on a high power LED board project. It requires to have 100 LEDs, of different types and colors. There will need to be 17 individual strands (need to be able to dim them separate.) Max current of any strand will be around 1A. It is planned on powering this from a single 24VDC supply. This can be done using a 2Oz copper board, the back will have a full aluminum heat sink, and active cooling is allowed. Board is pretty large, around 1' x 1'.

My first thought was to definitely use switching LED drivers, to avoid having to burn off excess power as heat. But the idea of using 17 separate switchers seems like a EMC nightmare that may not have a easy solution.

I thought about using a TPS92512 driver, which allows me to drive all of their clocks together from an external crystal to help with EMC. But 17 switchers on 1 board still doesn't seem feasible to me.

So, should I not even consider using switchers, and just figure out the thermals with linear drivers instead? Or is there any other option I may be missing?

Edit: Did some quick math. If they were all driven linearly we would have to dissipate around 150 watts total..

Since the most a single linear driver can dissapate is around 5 watts, that approach isn't an option.

Only other thing I can think of is to use a FET to drive each strand, and use several high power resistors per strand to help spread out the heat across the board.

Edit 2: Some needed information. LED strands can not be combined

(number of LEDs in each strand, TOTAL voltage drop across strand, voltage needed to dissipate assuming 24VDC supply, Current req'd)

7 LEDs, 20.2V, 3.8V, 1.2A
7 LEDs, 20.2V, 3.8V, 1.2A
2 LEDs, 5.8V, 18.2V, 1.2A
7 LEDs, 20.2V, 3.8V, 1.2A
7 LEDs, 20.2V, 3.8V, 1.2A
2 LEDs, 5.8V, 18.2V, 1.2A
4 LEDs, 13.6V, 10.4V, 0.3A
8 LEDs, 22.4V, 1.6V, 1.8A
4 LEDs, 12.4V, 11.6V, 0.8A
10 LEDs, 21V, 3V, 1.2A
10 LEDs, 21V, 3V, 1.2A
4 LEDs, 8.4V, 15.6V, 1.2A
8 LEDs, 16.8V, 7.2V, 0.76A
4 LEDs, 8.4V, 15.6V, 0.76A
4 LEDs, 8.4V, 15.6V, 0.76A
8 LEDs, 14.8V, 9.2V, 1.62A
4 LEDs, 12.8V 11.2V, 0.78A

Another thought I had:

We can drive strands 1, 2, 4, 5, 7, 8, 9, 10, 11, 13, and 17 directly using the 24VDC input, using a FET and resistors to limit the current. The rest of the strands we can use one switching driver each like I originally thought. We would then only need 6 switchers, and would dissipate only around 60W from the strands directly driven via the 24VDC supply.


texts:
When routing an I2C (SDA, SCL) bus or SPI (SCLK, MOSI, MISO) bus to multiple slaves is it preferred to wire the slaves in parallel or series? Below are two diagrams with distances labeled to help with answering. In all schematics I see people seem to wire in series, but why is this the case - what if capacitance of the path (A + B + C) < capacitance of (MNP)?

Parallel:

Series:


texts: Introductory Digital logic/design question

texts:
How can I abstractly describe a sequence of instructions/function at a register transfer level, given a certain set of instructions.

For example, here is the type of questions that we would be asked for our homework.

(1)Implement the following program repeatedly using a single 8-bit
adder/subtracter (AS) module, 8-bit registers, as few as possible as small as possible
counters and combinational modules of your choice.
The AS module executes addition, when control signal c1 is 0 and subtraction when
control signal c1 is 1. Every five cycles the 7-bit input variables b, c, and e are updated
with new values. All values (given and calculated) are positive. Values a, f, g, h, and d
should be available one each clock cycle, in their respective order.

statement 1. a = b + c;

statement 2. f = b + e;

statement 3. g = a − c;

statement 4. h = b + e;

statement 5. d = b − c;

And a more challenging question.
 Design a system that computes the following expression:
F = ax4
 + bx3
 + cx2
 + dx + e
The constant values a, b, c, d, and e are stored in five shift registers. Variable x arrives
every 8 clock cycles. Use the minimal number of shift registers, multipliers, and adders to
design the system.

Im not necessarily looking for answers to this, I just want to know if there is someone that can provide me with certain topics that would allow me to solve these types of problems. Essentially, I want to be guided in the right direction so that I may be able to understand this topic.
I understand we have to use ALU's and registers, but how can I translate this to some sort of state table and diagram so that i may implement the situation.

Thanks to all.


texts: Explain Idle, Sleep, Stop and Standby modes of power consumption in a microcontroller with examples

texts:
It is given in a website that "In Idle Mode, the CPU and Flash are stopped. The rest of the chip continues to operate in this mode. If you do not need to execute code, but are taking a sensor measurement with the A/D or communicating to a radio, Idle Mode should be used."
I am confused about how a microcontroller (STM32L475) continues to take sensor measurement even after the CPU and Flash are stopped. I think Reading data from a sensor is an instruction which the CPU needs to execute by fetching it from the memory which is FLASH. If CPU and FLASH stop, how does the rest of the chip or peripherals do their work in Idle Power Mode?


texts: Relay's maximum rating current and voltage

texts:
I'm looking at this Form C relay: IXYS LCC110

Its max load current is 120 mA and max voltage is 350 VDC. My question may be dumb, but can I use this relay to safely control a load that is only 5V but 700 mA?


texts: Good ARM development board for bare-metal development

texts:
I'm looking for an ARM development board for bare-metal (no underlying OS) development. Some criteria that I value:

1) External SRAM/SDRAM, at least 1MB
2) External Flash, at least 512kB
3) Built-in JTAG, or atleast standard JTAG interface
4) Nice, well documented and easily programmable accessories (UART, GPIO, USB, Networking)
5) Good documentation.
6) Not too expensive.

I've been looking at the BeagleBoard (and BeagleBone). It seems to cover everything except (4). Any other ideas?


texts:
I read a textbook and it states that:

  "The effects of electrical noise can be minimized using circuitry external to the MCU"

I don't understand how this scenario works. What does it mean with 'external circuitry'?


texts: Trying to read the data from an ASK RF transmitter

texts:
I'm trying to duplicate the operation of a simple RF remote control (for some remote power outlets). In the remote control there is an unmarked 8-pin microcontroller. I've worked out which pins are connected to the buttons on the remote and which pin sends the data to the transmitter part of the circuit (pin 6 on both, incidentally). The Tx IC is marked F115, after some googling it appears to be this one.

I'd like to read the data that is being sent from the unmarked MCU to the Tx so that I might be able to duplicate it with an arduino or ESP. Currently I'm using an ESP-01 module and some transistors to "push" the buttons. I need to determine the code that it sends to each remote outlet, I just don't know how to do that. I don't have a scope, so I'm wondering if it's possible to use the arduino itself to intercept the signal from the MCU to the Tx. I don't suppose it would be as simple as programming the arduino to receive a signal then connecting MCU pin 6 to the arduino? I'm not super well-learned in more complex stuff like this (RF and serial communication), but I'm trying to learn!

Please, if anyone knows anything that could point me in the right direction I'd be really appreciative. I don't know where to start, so I really need some input.


texts: Confusion with a measurement method suggested for an opamp input impedance

texts:
Before asking my question, I want to show the probe and scope model I use in the simulation:

In the above schematics the section inside the rectangle represents a scope probe set for DC coupling at 10X which is coupled to the scope's inner network C3 R6. I also set the compensation capacitor C4 such that for a very sharp square input the output at the scope end is a sharp square wave as shown in the below plots:

So now I will use this probe and scope model for my question.

The question is about the following task from a lab text:

Here I modelled this follower's input impedance and the probe-scope as follows:

What I understand from this is that, the extreme high input impedance of the opamp's non inverting input will not let us measure it correctly. This is because the max scope impedance is 10Meg and when probed it will be in parallel with the opamp's huge input impedance and the ratio of Vp/Vin will not reveal the opamp's input resistance, it will see the input impedance around 10Meg.

But at high frequencies as the text says the opamp's input capacitance dominates. So it mentioned one can measure the input capacitance by measuring the f3dB point. But probe's and scope's capacitors have big effect on this measurement. So by measuring Vp/Vin I can find the freq. for f3dB point and from the formula f3dB = 1/ (2 * pi * R1 * C1) and I can find C1 which is the opamp's input capacitance. But the problem is that probe's and scope's capacitance are effecting this measurement a lot. I checked with simulation and it doesnt make sense without putting the probe and scope circuitry into account.

The text is confusing and doesnt give an answer to this.

So my question is, is it possible to measure the input impedance here by using the methods mentioned in the text?

Edit:

uint128_t's answer gave me an idea.

How about if I first measure the 3dB point when probe&scope connected but without opamp and find the total capacitance(caused by the probe-scope system) for 3dB freq. I mean 1Meg and the total capacitance Ctotal will cause 3dB at a freq. we observe supplied by a generator.

And after this now if I also couple the opamp to the system and find again a new 3dB point and a new corresponding corner frequency, and again I can find the new Ctotal lets call this one Ctotal'. Now can we say Copamp=Ctotal'-Ctotal?


texts: What will be the value of resistor to be connected in series with freewheeling diode if brake coil is 110 V DC

texts: In order to quickly off the brake, what will be the value of resistor to be connected in series with freewheeling diode? Brake coil is 110 V DC.


texts: Relaxation Oscillator Issue, comparator self-oscillating at 25 MHz (40ns propagation delay)

texts:
I have a relaxation oscillator circuit, which is supposed to oscillate around 6 MHz, and mostly it oscillates in a very stable manner around it.

However sometimes it starts to oscillate at 25 MHz, which is the fastest oscillation available for this comparator (TLV3202) given its propagation delay is 40 ns. Some cases where this happens are:

on frequent on-off, I can put the circuit in this mode
bringing fingertip near inverting input, not touching just in air.
touching an open ended wire to non-inverting input.
also during normal handling of running circuit we have seen this.
As this circuit will be used for further capacitive sensing, we are in trouble.

A few observations:

touching non-inverting input with an open ended probe bring it back to 6 MHz
or power reboot also fixes it.

Circuit diagram:

PCB layout:

A few things that I tried to fix this, with no success:

putting a 10 pf capacitor between  comparator-output <----> comparator-non-inverting input.
putting a 200 ohm resistor on comparator-output.


texts: continuous vs discrete systems in control theory

texts:
What are the advantages and disadvantages of using continuous or discrete systems for control? I'm going to list some that occurred to me, but would appreciate if people help complement the list. (If this question doesn't belong here, please let me know, I'll delete it).
Advantages for discrete:

Data from the real world is discrete.
Computers are discrete, hence they can more easily deal with discrete control systems.

Advantages for continuous:

Sampling is not an issue.


texts: I would like to use a 30W RGB LED that is in common-anode configuration.  The issue is the voltage ranges for the LEDs are different, 20-24V for red, and 30-36V for green and blue.  Is it possible to run the red led at the same time as the blue or green?  If using PWM w/mosfets you still get the full 34V across the red LED I'm assuming that's not going to work.


texts:
have been trying to replace a capicitor on this inherited pcb. Sadly the negative pad for C6 (Orange circle) seems to be missing. Can anyone advise how best to get a capitor seated here?

Thanks.

PS no idea what’s going in the with the blue circle....


texts: SVPWM for BLDC Motors: Switching Losses vs Neutral Point Voltage Swing/fluctuation

texts:
I am implementing a SVPWM (Space Vector Pulse Width Modulation) scheme for a 3-phase inverter (3 H-bridges, nothing fancy) to control a BLDC Motor.

Since one can choose which zero vectors (000 or 111) to use, a huge variety of implementation alternatives are present. The main division seems to be between "2 leg active 1 leg completely ON or OFF" and "3 legs active" versions.

In the first variant, its clear that there is 33% less switching and this will lead to less switching losses. The second approach has more switching losses (3*2 compared to 2*2 per PWM period) but in many papers I have read its presented as "it has less neural point voltage swing".

I have no problem implementing any of the alternatives but I am having a hard time understanding the pros and cons of "less switching losses" vs "less neutral point voltage swing".

I am driving Gimbal motors which are designed to operate at lower speeds and I plan to have a full-fledged F.O.C (Field Oriented Control) at some point. My aim is precise control at lower speeds. The PWM frequency is at 20 Khz (center aligned) and i am using IFX007T from Infineon for the H bridges.

Any help is much appreciated on deciding which variant to use for my goals.


texts: Suppressing sparks when attaching buck converter to battery

texts:
i have bought a cheap DC/DC converter (24v to 19v, 15A, link). When i attach a 24v battery pack to the converter input i get sparks. Is there any way to suppress these sparks when i attach the converter?

Edit: I want to power a Intel NUC mini computer with the converter. My idea was to use a relay to turn the dcdc output on and off. Wouldn't the sparks damage the relay contacts or weld them ?


texts: a temperature sensor for battery heating system in cold environment

texts:
I'm making a device that will operate in cold environment. The ambient temperature will vary between -50℃ and -20℃. The sensor is supposed to monitor the temperature so that the microcontroller in my device decides, whether a battery heating system in the device runs or not. The temperature could change at a speed of 0.2℃/s.

What would be the best sensor type among a digital temperature sensor (like DS18B20), a RTD, and a thermocouple?


texts: Understanding capacitive load conditions for a microcontroller

texts:
This is from a PIC24E microcontroller datasheet.

My question is understand what does "load conditions for device timing" mean ?
Does it mean in order to maintain timing (say for a high speed PWM signal, or anything a designer wishes to maintain a sharp edge), the capacitive load ( parasitics + receive input) must be a max of 50pF ?

I'm confused about Table 32-15. Are these special case in which the Figure 32-1 is not true? For instance, Figure 32-1 states that all I/O have a CL = 50pF except for OSC2 which is 15pF. This will apply to all clocking modes and table 32-15 gives exceptions to this, such as OSC2 is not 15pF when in EC mode.


texts: I'm designing a readout circuit for a photodiode consisting of a transimpedance amplifier. I've noticed that the photodiode has a relatively large capacitance (320 pF). Are there any tricks/adjustments I would need to compensate for this capacitance (in terms of speed and noise)?


texts:
Can someone explain me what impact-ionization current means and when does it happen? As far as I'm concerned, it's about gate current leakage when operated with high Vds and Id. If I'm right, why does this happen? What are the consequences of this situation?

Thanks in advance.


texts: Why do we need an isolation transformer to connect an oscilloscope?

texts: My professor always insists that I provide power to an oscilloscope thorough an isolation transformer. What is the necessity of this? What is the risk if I don't connect it?


texts: Looking for advice on building a USB inline device to remap CapsLock key on USB keyboard

texts:
I want to build a small inline USB device that changes the CapsLock key to be a Ctrl key. I want to do this because I rarely use the CapsLock key. Unfortunately, I don't have admin on the machine, so I can't use the regular approach (ie: registry change, or PowerToys).
So I need a microcontroller with USB-A and USB-B (host and device?) that can read USB codes from the keyboard and then send them to the computer.
What works to do this?


texts: Convert decimal fraction to binary number

texts:
I have this code that works for me to convert a double into a binary representation, I want to know how to convert the Fractional Part if it were separately.
Example Function Prototype would be:
    int decimalToBinary (int Integral, int Fractional, int k_prec);

// Function to convert decimal to binary upto
// k-precision after decimal point
int decimalToBinary(double num, int k_prec)
{
    //int binary = 0;
    int NumF=0;
    // Fetch the integral part of decimal number
    int Integral = num;
    int count=0;
    // Fetch the fractional part decimal number
    double Fractional = num - Integral;

    // Conversion of integral part to
    // binary equivalent
    while (Integral)
    {
        int rem = Integral % 2;

        rem=rem&0x01;

        NumF=NumF|(rem<<count);

        Integral /= 2;

        count=count+1;
    }

    NumF<<=k_prec;

    // Conversion of fractional part to
    // binary equivalent
    while (k_prec--)
    {
        // Find next bit in fraction
        Fractional *= 2;
        int fract_bit = Fractional;

        if (fract_bit == 1)
        {
            Fractional -= fract_bit;
            NumF=NumF|(0x01<<k_prec);
        }
        else
            NumF=NumF|(0x00<<k_prec);
    }

    return NumF;
}


texts: Supplying less than 3.3V voltage for power inputs

texts:
I want to do a re-design for i.MX 6Dual/6Quad  CPU-based mini-PC, where one of the DC-DC converters used to supply 3.3V for its power inputs, is going to be replaced with a new DC-DC that outputs Vout=3.22v.
My main concern is that supplying 3.22 will not be sufficient for various devices on board, including this CPU.
I did a rigorous check for all devices that are connected to the 3.3V output, and turned out that 3.3V was connected to their VCC supply pins, which in all of them, the minimum supply voltage required for operation is lower than 3.22V.
On the other hand, some inputs had confused me. let's give some examples:

VDD_HIGH_IN input in i.MX 6Dual/6Quad : is 3.22V input is a good choice for its range? and how does -0.3V min voltage makes sense when we are talking about VDD HIGH?

VCC input for Micro SATA Disk Chip where it's VCC voltage range is 3.135V ~ 3.465V, is 3.22V input for VCC also sufficient in this case?

Since there are 3 DC-DC converters on board, and I want to replace all three of them out with a new ones out of price concerns, it turns out that in order to choose 3 similar converters, the DC-DC converter which used to supply Vout=3.3V, now will have to supply only 3.22V.
I measured the total maximal current that could be consumed from all devices that are connected to the 3.3V output (which is now 3.22V output) and the new DC-DC is able to provide such current.


texts: What's simplest way to measure mass or weight with Arduino

texts: I want to track the mass of a hanging window farm project. It seems like I should be able to get some sort of load cell device to interface with my arduino. What is the simplest way to do this?


texts:
I am a student. I acquired EMG signal (sampled at 1KHz) by using dry electrodes. At first, it was all noisy. I then applied a Notch Filter (@50Hz) and the signal looks better but still not great.

Any suggestions on the further processing of the signal? Thanks in advance.

I attach Signal vs Notch filtered Signal

FFT of the original signal


texts: How to implement an ADPLL in Verilog that locks onto an arbitrary sine wave?

texts:
I'm unable to figure out how to implement an ADPLL on an FPGA that can take in an arbitrary periodic input and lock onto its frequency (some finite range is okay) and phase. A square wave output will do.

As a first step I thought of assuming that the input is a sine wave. I know how to digitise the same using the onboard ADC.
How do I proceed from here?

Any links to existing code repositories that implement all or parts of this are welcome.


texts: How to find the actual measurement range of a temperature sensor, HTS221?

texts:
I am considering to buy the HTS221 Digital Temperature and Humidity Sensor by STMicroelectronics. The datasheet says the operating temperature of the sensor is from -40°C to 120°C. But on page 33 of the datasheet, they say under accuracy, 15 to 40°C = +/- 0.5°C and 0 to 60°C = +/- 1°C. They never talk about sub-zero and temperatures above 60°C.

Does the operating temperature (-40 to 120°C) mean that this sensor will not melt off during high temperatures like 100°C, but I cannot expect it to measure that temperature?
Does that mean that the temperature sensor can measure only from 0-60°C with the above accuracy and the rest of the measurements are going to be way off?


texts: Building a VCCS with AD8220 Instrumentation Amplifier

texts:
This question is to help me with my work in building a VCCS for the excitation signal of an Electrical Impedance Tomography measurement set-up to use with EIDORS. I have only basic knowledge in electrical engineering since I'm a computer science student.

I'm trying to build a similar system as described in this paper for my Electrical Impedance Tomography (EIT) system. In particular, I took this Figure from the paper as a reference for building my test system:

I am generating a sinusoidal excitation signal (10kHz-100kHz) with the AD5930 DDS waveform generator that has a full-scale current output of 3-4mA and 0.56V peak-to-peak.

I want to build an AD8220-based VCCS to generate the EIT excitation signal. However, I don't know how to build a VCCS, especially with the AD8220 instrumentation amplifier, and was hoping someone could help me with that?

The constant AC current should be less than 1mA, for example, around 100uA p-p would be sufficient.

What I have tried so far: I used LTSpice to simulate the following circuit to try and build a VCCS:

However, I don't know how to set and calculate R2 given R_Load and if this really is a VCCS and the right approach to this.