texts: How to verify the contents of ROM in FPGA

texts:
I'm new to FPGA and VHDL. I'm using Xilinx Spartan 3A.

I have wrote a custom ROM with initalization file .hex. I would like to verify that the rom is initalized with the values in the .hex value. Is there a method to verify the contants that is loaded from the file.

here is my design file
LIBRARY ieee;

 USE ieee.std_logic_1164.all;
 ------------------------------------------------------------------
 ENTITY rom IS
 PORT (address: IN INTEGER RANGE 0 TO 15;
 data_out: OUT STD_LOGIC_VECTOR(7 DOWNTO 0));
 END rom;
 ------------------------------------------------------------------
 ARCHITECTURE rom OF rom IS
 SIGNAL reg_address: INTEGER RANGE 0 TO 15;
 TYPE memory IS ARRAY (0 TO 15) OF STD_LOGIC_VECTOR(7 DOWNTO 0);
 SIGNAL myrom: memory;
 ATTRIBUTE ram_init_file: STRING;
 ATTRIBUTE ram_init_file OF myrom: SIGNAL IS "test.coe";
 BEGIN
 data_out <= myrom(address);
 END rom;

I have used a test bench and I tried to simulate a ROM using initialization file but I get undefined output according to that image.

Test bench:

-- Entity

library ieee;
use ieee.std_logic_1164.all;

entity tb is
end entity;

--#############################################################################
-- Architecture

library ieee;
use ieee.numeric_std.all;

architecture sim of tb is

  --===========================================================================
  -- Clock and reset decl.

  -- Clock
  constant CLK_FREQ : real := 100.0E6;  -- Clock frequency in Hz
  signal clk        : std_logic;

  -- Reset
  constant RST_PER : time := 100 ns;    -- Reset period; and then waiting for rising clk edge before deassert rst
  signal rst       : std_logic;

  --===========================================================================
  -- Device Under Test (DUT) decl.

  signal dut_address  : integer range 0 to 15;
  signal dut_data_out : std_logic_vector(7 downto 0);

  --===========================================================================
  -- Test control decl.

  -- None

begin

  --===========================================================================
  -- Clock and reset impl.

  -- Clock generation
  process is
  begin
    while true loop
      clk <= '1';
      wait for 0.5 sec / CLK_FREQ;
      clk <= '0';
      wait for (1.0 sec / CLK_FREQ) - (0.5 sec / CLK_FREQ);
    end loop;
  end process;

  -- Reset generation
  process is
  begin
    rst <= '1';
    wait for RST_PER;
    wait until rising_edge(clk);
    rst <= '0';
    wait;
  end process;

  --===========================================================================
  -- Device Under Test (DUT) impl.

  rom_e : entity work.rom
    port map(
      address  => dut_address,
      data_out => dut_data_out);

  --===========================================================================
  -- Test control general

  process is
  begin
    -- Wait for reset release and clock.
    wait until rst = '0';
    wait until rising_edge(clk);
    -- Address apply and data output check
    for address in 0 to 15 loop
      wait until rising_edge(clk);
      dut_address <= address;
      wait until rising_edge(clk);
      -- Check output of ROM
    end loop;
    -- Run for a while
    wait for 1 us;
    -- End of simulation
    report "OK   ########## Sim end: OK :-) ##########   (not actual failure)" severity failure;
    wait;
  end process;

end architecture;


texts: How to solve infinite grid with the observing terminals at diagonal of infinite square matrix?

texts: The answer given is 2/3ohm solution is not given but I can expect how they got that answer but can't justify the way.


texts: Is the slide-lock on an SD card optional?

texts: When enabling the write lock on the side of an SD card, is the write protection a physical limit on the SD card, or a flag sent to the reader or OS telling it to please not write?


texts:
On the arduino uno (= ATmega328/P), how can I manually clear the timer 1 output compare signal?

The purpose of the code is to generate some output pulses after a precise interval from the input pulse. There are two output channels that need to be driven, potentially with different delays. The pulse length isn't critical, just needs to be at least 8µs long, but the timing for the rising edge needs to be accurate.

Currently my code looks like this:

#define MAINS_PERIOD 16667 // in microseconds

ISR(TIMER1_CAPT_vect) {
    GTCCR = _BV(TSM);
    TCNT1 = TCNT1 - ICR1 - MAINS_PERIOD + 1 + 300;
    GTCCR = 0;
}
ISR(TIMER1_COMPA_vect) {
    delayMicroseconds(8);
    OC1A = 0; // <---------- what do I do here?
}
ISR(TIMER1_COMPB_vect) {
    delayMicroseconds(8);
    OC1B = 0; // <---------- what do I do here?
}

void setup() {
    TCCR1A = _BV(COM1A0) | _BV(COM1A1) | _BV(COM1B0) | _BV(COM1B1); // set output on compare match, normal mode, prescaler /8
    TCCR1B = _BV(CS11) | _BV(ICNC1) | _BV(ICES1); // input capture noise cancel, positive edge
    TIMSK1 = _BV(ICIE1) | _BV(OCIEA1), | _BV(OCIEB1); // generate interrupts for input capture, A/B compare match

    pinMode(8, INPUT);  //set data direction
    pinMode(9, OUTPUT);
    pinMode(10, OUTPUT);
}

I could potentially reconfigure the timer's output mode to clear on match and then force a match, but it seems like there ought to be a more straightforward way to do it:

ISR(TIMER1_COMPA_vect) {
    delayMicroseconds(8);

    TCCR1A &=~ _BV(COM1A0);
    TCCR1C = _BV(FOC1A);
    TCCR1A |= _BV(COM1A0);
}

Just clearing the output pin register bit (PORTB &=~ _BV(PORTB1);) won't work in this case because the port register is ignored whenever an alternate function (like the timer output) is enabled on the pin.

Alternately, if there is a way to get the timer outputs to clear on overflow (some kind of undocumented 16-bit PWM mode?) that would be even better, but I doubt there is a way to do that.


texts: Battery connectors inside a UPS, F1 for F2 subsituted, consequences?

texts:
I have a 10-year old APC UPS.  Naturally the 12V SLAs were dead, so I bought 8 new ones of similar specs.

After swapping out the batteries the unit starts and charges fine, but when I try and run a load on it then pull the line input power, the UPS shuts down and lights up the red X "battery failed" light while pip-pip-pipping.  The load goes down hard at this point.

On inspection, the original batteries used the F2 connector (pictured on the right), and my replacements use the smaller F1 connector (on the left)

Question Is it likely that using the wrong connector with the original F2 wiring is limiting the current that can be drawn?  The battery back reads about 52 volts (its 48v nominal with 12V x4 x2 so a total of eight 5Ah batteries)   or is my UPS simply broken ?

I don't have the resources to buy 8 more batteries on the off-chance this is the root cause.
Should I recreate the battery pack internal cabling with F1 spade connectors - would that help?   Or do something else to improve connectivity?
UPS is an APC 2RU rackmount job rated at 2.2kVA, and has a network management card, so its not a cheap and nasty home-grade device.
I've changed batteries in over a dozen different UPSs in the last couple decades, so while not an every day thing I haven't made any significat mistakes.  Size range from 275VA up to a 6kVA emerson monster.
Data sheet for the batteries I used


texts:
If I use an LM311 Comparator, then we are required to connect a pull up resistor at the output. Does the square wave output depends on the value of the voltage the resistor pulls up to?

Would it be that if i had a 5V on the pull up, then the output would be a square wave with 0V to 5V(max).
And for a 12V pull up - a 12V to 0V Square wave?


texts: Why are capacitors used parallel to transistors

texts: In the circuit attached. There are two capacitors. One is parallel to "PWR LED". Although I understand it delays the turning on and off of the LED, why would you need that? Also, the other capacitor is connected in parallel to the phototransistor. This connection I completely fail to understand the purpose of. This circuit diagram is of a flame sensor, which generates an output when the phototransistor detects IR.


texts: Maximum separable distance between Micro-controller and LM35 (temperature sensor)

texts:
I am using LM35 temperature sensor to sense temperature of surrounding. I have connected LM35 to Micro-controller through a jumper of about 20 cm. It is working fine.

Now I want to increase distance between Micro-controller and LM35 to about 10m-12m.

Is it possible? If not, how it should be done for such distance and what is maximum separable distance for LM35 and Micro-controller?


texts: How can the equation V=I*Z be applied using complex numbers in AC circuits

texts:
So reading chapter 9 in James W. Nilsson, Susan Riedel-Electric Circuits (10th Edition) book explains perfectly how can complex numbers be used to add and subtract sinusoidal waves as in the below figures:

due to the property that adding the real parts of any two complex numbers is equivalent to adding the complex numbers as a whole and getting the real part of the result which is very intuitive and makes sense, however this is not true for multiplication or division(multiplying the real parts of two complex numbers is not equivalent to multiplying the complex numbers as a whole and getting the real part of the result), which makes me wonder how can Ohm's law for AC Circuits (V = I*Z) be possible using complex numbers to get the voltage by multiplying together the impedance and current where both are complex numbers.


texts:
I need to detect the presence of large metallic objects. The detector will be on the ground. The detectable object will be around 60-70cm away. The detector will need to be protected to support heavy weight. The detector will be on/near/under asphalt and cars might run over the detector. I am not sure about what type of detection will be suitable for this scenario.

What possibilities of detection mechanisms exist for such a scenario?
What type of detector will be most accurate?
Which of the options would be most cost effective?


texts: Reverse Current leak Battery+Diode in parallel

texts:
on my design, I am using two coin batteries in parallel and each battery has a Schottky diode in series to block the reverse current, in theory, it will avoid the higher potential battery "charge" the lower potential battery.

But I am facing a higher current consumption when the two batteries are connected to the circuit, probably in reverse leak
Single Battery connected avg consumption 2.6uA
Two Batteries Connected Average Consumption 7.8uA
What should be the recommended to avoid that probable reverse current leak?
Change diodes, add a second diode in series (2 diodes per battery), replace diodes per an ideal diode IC?
update
diodes:MBR0520L
The voltage at uC e.g: 3V it takes higher voltage between the two Batteries, usually exist few 1-15mV in the difference between each battery


texts: DMM fault: diode test function not working

texts:
I have two Protek 506 digital multimeters, and they both have a fault with their diode testing function.
The first meter only displays the word "OPEN" with a voltage of 3.999V below it, and the second one only displays the word "Shrt" with a voltage of 0.000.
Neither of the meters will shift from their respective displays, no matter what I do.  I've never used the diode test function before today, and I was surprised that my first meter had this fault, so I tried the second meter, which has barely been used, and was surprised/disappointed that it too should have a faulty diode test function.

Is this a particular problem with the Protek 506?
What would be causing the problem?
Can it be fixed?


texts: Collector-Emitter short but not Base-Emitter

texts: I have a power amp that blew the pair of transistors(2SD1047 and 2SB817) at the output. The positive side 1047 is totally shorted, all junctions, the negative side 817 is only shorted Collector-Emitter. My question is how can that junction short without affecting the Base-Emitter junction?


texts: Best way to affect a compass in 2 meter distance

texts:
Visitors of two public exhibitions A and B are equipped with compasses.

Exhibition A:

I want to guide these visitors along a certain path throughout the exhibition by "overriding" the earth magnetic field so that they can follow there compasses "north" along the path. The path where this deviation should work on is no wider than 1.5 meters. This deviation can be turned on and off by a switch (thus can not be accomplished by permanent magnets).

Exhibition B:

I want to notify the visitors of events by generating a short magnetic pulse that will shortly deviate their compasses. This should work over a ground circle area of at least 1 meter radius.

Update 13th April:
The direction of deviation is not of importance.

Annotation:

Update 13th April:
The path will guide the visitor along a rectangular playing area of about 20mx20m. Due to the nature of the installations, the only options to install hardware are the sides and the floor (max. height 20mm).

Assumptions:

Local earth magnetic field strength is below 65 uT.
There are no other electromagnetic influences.
Height of compasses above ground are 2 meters maximum.

Research so far:

I built a small solenoid magnet with about 400 windings, 4.8V and iron core. Although getting up to 1400 uT at the magnet itself, it rapidly drops in the distance (between ~1/r^2 and ~1/r^3) to a level where it cannot be distinguished from the earth magnetic field; reaching 70uT as soon as 20cm.

In order to reach compasses in 2 meters height (200cm distance, 20cm*10) I would have to amplify the strength by a factor of 1000 (10^3, because of 1/r^3) in case I assume a Dipole (Wikipedia). I doubt this can be accomplished with my small self-built magnet.

What would be the most cost- and time-efficient way to accomplish exhibition A and B?

In particular I'm interested in:

how to simulate such an environment on a computer,
what kind of magnet type/layout is suitable,
can this be accomplished with off-the-shelf equipment,
are there any dangers for the visitors.

I'm happy to provide more details if needed.


texts: I want to translate -200uV to 800uV coming from a sensor to a range of 0-5V using Op-amp. Is there any way I can do it?


texts: How do I interpret the zero-g level change vs temperature specification for this accelerometer?

texts:
This is an extract from the datasheet of the MPU6050 sensor.

I was expecting the level change vs temperature to be in units of mg/oC. Instead, as you can see, the temperature range is specified separately as 0 to 70oC and the level is in mg. The sensitivity change w.r.t temperature for the same accelerator is given in units of %/oC. So this doesn't seem to be an error due to oversight.
My current interpretation is that this spec means that the manufacturer only observed the variation but wasn't able to characterize it. What do you think?


texts:
I'm putting together a Morse code decoder circuit with Arduino (a photodiode sensor connected to an analogue pin, the Arduino will then decode the high and low light pulses the photodiode receives to be dots and dashes) and I'm currently working on the sensor portion of the circuit.

I have the following amplifier circuit to amplify the signal coming from the photodiode.

As well as this I also took the optical filter off of an old barcode reader and put it over the photodiode so that mainly the light from the red laser pen that I am shining at the detector (10 meters from it) should get through.

The speed at which I'm modulating the laser is proving to be the main problem; I'm modulating the laser by turning it on and off every 50 - 200 microseconds; if using a plain photodiode on it's own the photodiode rather than reading this as highs and lows just waits till it has received enough pulses to saturate the sensor and then turns on, it's acting more like a low pass filter.

So I chose to use this amplifier circuit instead however I'm struggling to get the correct resistor values to give me the sensitivity I need; I've tried from 10k up to about 5Mohm but everything is either too sensitive or doesn't even register.

Can anyone recommend some resistor values for the above circuit or another amplifier circuit that might be better suited to the sensitivity and speed that I need?

For extra info, as well as the above I'm thinking about further reducing ambient light getting to the sensor by either pointing the sensor and the laser at a surface a few mm from the detector and measuring the reflections or by putting a thin piece of paper over the sensor that the laser would shine through and hit the sensor that way.

Any help much appreciated

Edit 2:
Here is the current circuit after Photon's suggestions.


texts: What would be the difference between the output of a power bank and a laptop usb port?

texts:
I have an encoder which I have been successfully using when powered from my a USB2.0 outlet on my laptop. I need to be able to run it whilst disconnected from the laptop and so tried powering it from a power bank. This is only intermittently powering the encoder with more noise in the returned signal when it was working.

The encoder requires between 4.75V and 5.25V the power bank supplies 5V

The encoder requires current of 0.07A the power bank provides up to 2.1A

The encoder is the MAXON EASY 16
https://www.maxongroup.com/medias/CMS_Downloads/DIVERSES/ENXEASY_EN.pdf
Pg 19

The Power bank is:
http://www.energizerpowerpacks.com/product_page.php?p_code=P0014&l=en

What is different between the usb port and the power bank? And how could I replicate the output of the usb port without having to connect to a laptop?


texts: Input sound to arduino via microphone jack

texts:
I'm designing a gadget which will light up LEDs using a microcontroller. I'd like for it to respond to an audio signal, so I was thinking there are a lot of ways I could do it: If I can accurately sample the voltage from a microphone or an analog signal (microphone out) fast enough I can run an FFT algorithm on the microcontroller and find out the gain at any arbitrary audible frequency, and flash the lights in tune, or other fancy fun stuff.

If it cannot sample at 44kHz, I can still get some meaningful data subject to aliasing. I'll need to flip through some textbooks in that case...

If my microcontroller is too slow to do a fourier transform, I figured I could still create an AC band-pass filter (can do it with two capacitors and two resitors) and amplify it so i could still give my microcontroller a couple of analog inputs representing certain frequency intensities.

So I think I am pretty sure how this plan works on a big-picture level, but I'm not sure where to start to figure out how to wire together my components. I have a couple of different op-amps, a few BJT's, some assorted resistors. My assorted capacitors are still in the mail. I have a few arduinos which will hopefully be sufficient for prototyping. I also have the requisite materials for printing my own circuit boards (copper plated laminate, etching acid, laser printer, iron) and stuff for soldering. However I do not have an oscilloscope or function generator, only a DMM and a current- and voltage-controlled DC power supply.

So an audio signal is carried over two wires. The difference in potential between the wires (and perhaps to some degree the current??) represents some function of the air pressure displacement due to sound at the point in space occupied by the microphone. This is due to the common design aspects of nearly all speakers and microphones. This would mean that this voltage will go both positive and negative (no DC bias, as I understand it) and therefore would require offsetting so the analog input read will not clip half of the waveform. How many volts would the amplitude of the signal be, from the headphone out on a sound card for example? What about an iPod? Could I play an mp3 of a sine wave on my computer, and examine the AC voltage on the audio jack using my DMM? How do I know what frequency range the DMM will make accurate AC voltage measurements?


texts: Why don't they use more than 12v in high power car audio?

texts:
In every single high-powered car audio system I've seen, in person and on the internet, the amplifier has been run off of the main 12 volt power system.

Such systems feature multiple parallel runs of heavy-gauge (Commonly 2 AWG or lower) wire between the battery and amplifiers and several alternators in parallel to supply the required current, which is in the hundreds-of-amps range. For a 5KW system, the maximum current would be around 400 amps.

Additionally, modern class D subwoofer amplifiers often have easily 2/3 of the internal space dedicated to converting the ultra-high-current 12 volt input up to a higher voltage, typically 70-100 volts, to drive the subwoofers.

Instead of using the 12v and boosting it, an alternative approach would be to have the alternators wired in series or using higher turn count windings to generate a higher voltage (70-100 volts as above) and run the output stage directly off of that. It would be a much simpler setup, as you could omit the voltage booster section of the amplifier and would only need the output stage and signal processing.

Why isn't the latter setup used in high-power car audio systems?

[Edit] For clarification, I am not concerned with "normal" (~1kw or less) car audio setups. I'm asking about competition builds where they are using extremely high amounts of power and are so weighted down with equipment that their primary purpose is to make noise and set SPL records, not be everyday commuting vehicles.


texts: What is this component on circuit schematics?

texts:
It's a resistor like coloured 2 pin component from a power supply board of a home theatre, with a glass-transparent aspect. I'm a hobbyist and not into complex circuit till now...  looking for an answer online but couldn't find anything.

Thanks


texts: Unknown ticking sound on bad ite power supply

texts: I have a power supply with the model number NU70-1120520-l1. It is supposed to have an output of 12vdc@5.2A. When i test the voltage i get a reading of 1-2vdc so i opened it and i hear a ticking with the frequency of about 2×/second. After removing the heat sinks and testing the voltage again i got a proper reading. So whatever the problem is its intermittent. But as far as i can see there is no relay or anything else i can see that would make such a noise. When i unplug the supply the noise decreases in frequency and then stops. What could cause such a noise in this video. https://www.dropbox.com/s/qrl4aqnctn70doh/20171029_222750.mp4?dl=0 It would be much easier to replace the power supply but i am interested in the knowledge i will gain from diagnosing the problem with the circuit.  I can identify certain parts of the circuit and have a basic understanding of most electrical components.


texts: How the electric water heater and stove works?

texts: I notice that some appliances have heating  elements such as electric stove and water heater. I know that both of them using heating elements maybe some type of a resistor or something. I want to know more about them since I notice in my house, the hot water coming out of the tap shocks me. So maybe the earth wire is not connected but in which case, this happen ? Is it because the the heating elements in the electric water heater got rusted thus water more conductive ?  Does anyone have any links that explain the working principle of each devices please? I need them.


texts: Uncertainty in op-amp propagation delay?

texts:
I'm using an OPA211 amps in a simple differential-to-single-ended configuration (a subtracter circuit, with all four 10k 0.1% resistors). Each OPA211 has a 50-ohm resistor in series at the output and going to a BNC edge connector.  Traces are really small --- approx. 1.5mm from OPA's output pin to the resistor, and 1mm from the resistor (the other resistor's pin) to the BNC connector.  I attach the figure with the relevant parts:

C12P and C12M are decoupling capacitors (0.1uF X7R), and CB12P and CB12M are the "bulk" decoupling caps (10uF tantalum).  On the left there's the two inputs and on the right is the BNC edge connector.

I built two of these to simultaneously measure two signals on a device we're studying --- as a "debugging test" or "sanity check test", I connect the two OPA211 boards to the same signal, at two points in the same twisted-pair cable about 2 metres apart, and I see a time difference of about 70 nanoseconds!!  (that's at least 10 metres of cable at a conservative estimate of 1/2 velocity factor).  Since I'm measuring the same signal on the same cable just two meters apart, the delay between them should be no more than 10 or 15 ns, assuming a velocity factor between 1/2 and 2/3).

I have double- and triple-checked those values --- my question is: can this difference be attributed to a large difference in the input-to-output propagation delay between the two OPA211 amps? (the datasheet says nothing about this)  They are likely manufactured in the same batch, as I got both from the same cut-tape that came from the same Digikey order.  The two boards were next to each other, so their temperatures and humidity conditions would have been essentially identical.  The cables from the device to each of the OPA211 boards had identical length, and the coaxial cables from the OPA211 to the digital oscilloscope also have identical length.

If the answer is yes, and there can be such a difference, my follow-up question would be:  is the propagation delay in the OPA211 amps consistent?  (i.e., if it is XX ns today, could I expect it to be the same XX ns for a reasonable amount of time through its lifetime?)

Thanks


texts: I want to know the name of this below component

texts:
Its a turn Knob switch for setting timer and push start in Samsung microwave oven
I also want to desolder this component. How to do that?

https://www.buyspares.co.uk/microwave/mw87l-mw87l-bxeu/assy-key-module-dkm-mw87l-key-module/product.pl


texts: output voltage of an operational amplifier

texts:
A student designs an electronic sensor to monitor whether the temperature in a refrigerator
is above or below a particular value. The circuit is shown below.

Question: An operational amplifier (op-amp) is used as the processing unit. Describe the function
of this processing unit.

Solution: gives a high or a low output / +5 V or –5 V output
dependent on which of the inputs is at a higher potential

My enquiry: Can the output value be between +5 V to -5 V in this case? Or should it only be saturated( +5V or -5V) because this is an ideal op-amp? Or should it be saturated because of other reasons such as: there is no negative feedback to reduce gain. Hence, it has to be saturated. So that, only types of circuits (op-amps), which can be both saturated and non-saturated are those with negative feedback -only inverting and non-inverting amplifiers.

To be more specific, my question is that which type of circuit can the output voltage be saturated or non-saturated.

Thank you very much for your help. My writing is quite poor. If you don't understand anything, please leave a comment. I would try my best to clarify.><


texts: Help in assessing the input mains circuit integrity

texts:
I've been working on designing a (220-380 VAC) 3/4 wire  phase energy meter and in terms of metrology operation,  things were working very well quite similar in terms of metrology if compared to a commercial unit. Now I'm no expert in mains power electronics circuit design so I opted to integrate an off the shelf AC/DC flyback power supply, which when integrated in the meter worked well in lab conditions. I've followed and implemented the mains Input protection circuit going into PSU which is specified by the PSU manufacturer but to be honest I feel helpless as I have no idea how to calculate/know how and why the values are specified in this stage, I need to be able to know how much energy/ voltage and the where bouts of the circuit operates in a surge, fast transient and ESD situation since I plan on doing a pre-compliance test and one of the tests I'm concerned with is if the input protection fails then I have not backup plan so I would really appreciate if someone would kindly share his insights and knowledge on how to pre-simulate or calculate the values of the input circuit below in order to pass the following test conditions below as well.

Schematic of the mains input circuitry with the power Supply

Test 1

Test 2

Test 3

Some information on the MOV used on each line (230 VAC

My questions :

How do you calculate/simulate or choose the correct MOV model/value for the above application to pass the test conditions mentioned above?
Will the current input stage of the power supply survive the tests mentioned above?

Final Note: I come from an Electronics and Communications background and i have done a reasonable amount of work in low voltage (analog, digital) board designs but I'm no expert in this subject but I'm willing to learn. I know how to simulate how an AC signal going in to a bridge rectifier and analyse the output; you know basic stuff that most of us learned during undergrad, but the (fast transients, etc) on an AC mains situation, I've never worked with such case. I'm having a hard time on how to figure out how to model and simulate the MOV in the simulation programs (LTSpice, Proteus ISIS & TI TINA).


texts: Photo resistor is giving off an unsteady output, how can I fix that?

texts:
I just started out with Arduino, and for my first project, I need to use a photo resistor to get an accurate reading of ambient light in my room.

Problem is, the photo resistor is not giving off a steady output, even in a very steady light. For example, in daylight conditions in my room, the Analog Pin Monitor shows that the photo resistor output varies from around 70 to 80:

This problem becomes even more pronounced when light levels are low - I can't get a steady, accurate output. What can I do to fix this? Is it the way I'm wiring the thing? Let me know if you need any additional information, and I'll gladly provide it.

Thank you in advance.


texts:
I need to generate 0-15V output PWM singal ( max out put current is 4.5 mA only), using micro controller PWM feature. I observe one Design by using Two Transistor(PIC 1) ,I don't why two transistor needed for this , I think this can be done by sigle transistor only (PIC1). Tansistor used is MMBT2222A NPN.

Q1) One reason I can think , to keep same polarity of both input and output signal, but does it matter if some load need PWM input to drive it.

Q2) R1, R3 and R7 is to protect transistor from floating base condition , Correct me if i ma worng.


texts: The NUCLEO F411RE Works with float point?

texts:
I need a MCU to works with Wifi and Floating point for PID application. In the later I acquire a Wifi expansion board, but I wants know if the STM32 NUCLEO FR11RE works with a Floating Point. I don't find this information in web.
http://www.st.com/en/evaluation-tools/nucleo-f411re.html


texts: Can the DNL error of ADC be less than in negative more than 1LSB

texts: I have seen ADC with DNL error of more than +1LSB but did not see DNL error of -1.5LSB or -2LSB. In a practical ADC is it possible to have DNL in negative more than 1LSB


texts: On what inherent parameters does the speed of mosfet depend in a SRAM cell circuit?

texts:
I want to design 3D IC with 2 stages for a simple SRAM cell. Some of the MOSFETs will be on the top stage while some on the bottom stage.

The MOSFETs on the top stage are supposed to be degraded in performance compared to the MOSFETs on the bottom stage due to material fabrication issues. I want to know what exactly slows down the MOSFETs on the top stage.

Does the speed depend on the mobility of the charge carriers?
What are the main parameters that decide the speed of a MOSFET apart from its intrinsic capacitance?


texts:
I have 3 "Emitter-Coupled" Oscillator, the difference is that I don't use a resistor on the tank circuit and I do vary the Inductor inductance. They're close on the PCB and they got some disturbs, if only one is running everythings is great, but if the others starts to oscillate, then everything got messed up. What can I do to fix this?
Everything got messed up: when more than 1 oscillator are working, their frequency isn't as stable as before, take for an example, running alone Osc 1: 110kHz, Osc2: 75kHz, Osc3: 45kHz, they oscilllate about 500Hz, but when more than 1 are working together, it seems like they frequency connect to each other.
I'm using this circuit as a "Metal Detector", so when I got some metal stuff near my inductor a LED should turn on, but when something get near to Ind from Osc1 if more than one is active, multiple leds will turn on.
My Oscilator are close, my inductors not much.
UPDATE: Tuned them on the same frequency, used 500ns on my oscilloscope and now my wave is looking like a hysteresis.
Edit:
Trying to clarify myself.
My board is 3 oscillators, like the one I said on first line, my tank circuit is capacitors, a coil 1:1 and a inductive loop, this one is kinda far from my board. I have them on a 8051 which I'm measuring their frequency and checking if there's a metal near.
About AC analysis I'm trying to do the things the way I know, I don't know much about oscillator nor Control theory, so I'm just observing things slowly. About the capacitor I can try, another notable thing is, a circuit like mine that works have 2 differences, their oscillators are far apart from each other and they use Neon Lamp to protect the loop while I use a bourne gas discharger. I read that gas discharge have a high capacitance, would that interfer this much?
Tried to couple each oscillater voltage supply(5V) using a 100nF ceramic capacitor, still the same problem.
I guess I have a problem with the stored energy on inductor, how could I eliminate "odd" current, I mean eliminate the current that was brought by other oscillator or the metal messing up with the magnetic field? Also, tried using a 1M resistor parallel to LC Tank, nothing changed, should it be minor?


texts: What happens as the gate voltage continually increases on a MOSFET?

texts:
I wanted to ask a quick question regarding mosfets. and fets in general.
When the gate voltage is increased, the current through the drain doesn't increase proportionally; correct? Current through the drain increases less and less with each volt? What exactly happens? I understand we reach the threshhold voltage and then go into the ohmic region. For an increasing Vgs does the region go from saturation>threshhold>ohmic? Or am I off? Is saturation only achievable with too high of a Vds?
Or would it theoretically saturate with continuing increasing of Vgs? Does the device breaks down before the current through the drain could saturate with an infinitely high gate voltage? I just want to understand what happens when the gate voltage keeps increasing with a constant Vds. Does it stay in the linear region until the mosfet blows up?


texts: STM32L073xx Internal Bootloader - Get Flash Size issue

texts:
I tried recently to develop custom app flasher (based on stm32loader python module) for STM32L073xx microcontrollers but I stuck at one point.

This lib tries to obtain flash size from micro because for the same chip UID (0x447 - STM32L07x/L08x/L010) we can have different flash size. Lib sends command to read memory (cmd 0x11 0xEE) and now starts my problem:

flash size is stored at address 0x1FF8007C (RM0367, section 34.1.1)
internal bootloader allows to read memory in range of system memory: 0x1FF00000 - 0x1FF01FFF (AN2606 Rev35, ch.56 "Device-dependent bootloader parameters", STM32 series L0, PID 0x447)

It causes that when I try to read flash size from this address, I receive response 0x1F (NACK) and i cannot continue process.

Of course I could copy flash size byte somewhere in RAM before jumping to system bootloader or assume some flash size but then pc application won't be robust for all chips.

How it should be handled in proper way? Is there another address where flash size is stored?

Now I'm able now to read whole flash content, but there is new challenge. I've tried to perform mass erase to prepare flash for writing new content and surprise surprise...bootloader returns NACK for any type of mass erase!

My communication looks like that:

enter bootloader
send 0x7F, get 0x79 (ACK)
send 0x44 0xBB, get 0x79 (ACK) - Extended Erase Memory command

now i tried following:

send 0xFF 0xFF 0x00, get 0x1F (NACK) - Mass Erase
send 0xFF 0xFE 0x01, get 0x1F (NACK) - Bank 1 Erase
send 0xFF 0xFD 0x02, get 0x1F (NACK) - Bank 2 Erase

None of them work...any suggestions?


texts: Subwoofer hums when no audio source is connected

texts:
The hum stops as soon as an audio source is connected or any metal part of the subwoofer is connected to the ground of a socket.
Does anyone have any idea what the problem is?


texts: Finding datasheet for this MOSFET! (SMS5408 0932)

texts:
This component carries the markings SMS5408 0932 is busted! It is part of a 1000W psu of a flagship subwoofer of a (very) respectable brand, and I can't find any datasheet at all for it!

I assume it is a MOSFET because of the G,D and S markings on PCB. Only thing I could find for the SMS was this company:

http://www.siliconmicrosystems.co.uk/contact.html

that seems to provide asic services, doesn't seem to manufacture components. Also couldn't find any reference for 5408 except diodes.

Usual websites like alldatasheet, datasheetcatalog, etc didn't bring anything up. Contacting the manufacturer is no good, they've sent me another unit so no one would have to worry about repairing anything. But I really won't let this off because I can't find a replacing mosfet!! ;)

New image (PCB backside):


texts: In LCD/LED displays, does the back light strobe or remain on?

texts: In LCD/LED displays, like the ones used with computers or for watching TV channels. Does the back light strobe in sync with the refresh rate or does it remain on all the time?


texts:
I salvaged a few components like that from some old ISA Ethernet card (10Base2 + 10BaseT combos), many years ago. If my memory doesn't fail, those boards were replaced by 1995, I kept them, and dismantled them somewhere by 2004...

Now I just found the time ;-) for asking about it. It´s a DIP package (fits perfectly on a breadboard).

I did some googling, I founded that it is a DC-DC converter, but I found no datasheets for those 20+ years old obsolete components...

There are clearly labeled pins VCC, IN, OUT, and G.

What could be the pins 1, 2, 3, 4?

What could be the search terms in order to find information about this or a similar device?

I'm pretty sure that I will not find an use for this, but, I think you'll understand, this is not my objective.

I sincerely hope that I didn't hurt your eyes (not so much) with those words that I wrote in a language that, obviously, is not my home language. :-)


texts: Are there thermovision cameras available to hobbyists?

texts:
Years ago, while investigating a short, it came to me that using a thermal vision camera would help an electrical engineer in a lot of situations. Checking it then, such devices were prohibitively expensive, especially for a hobbyist like me.

Recently I saw the "Mµ Thermal Camera" campaign, so there's some movement in that direction. Also, technologies keep improving, and I'm wondering now - are there any affordable thermal vision cameras that are suitable for EE stuff (like finding shorts, analyzing heat issues, checking for unexpected problems, etc — the Mµ guys seem to be focused in a different direction)? Anybody played with such technology to report on pros and cons?

To clarify - I'm not looking for shopping options. More interested in the general state of the market.


texts: I want an opto-isolated MOSFET driver that works at high frequency

texts:
Is there an opto-isolated MOSFET driver that works at high frequency?

If possible show the circuit.

It's for ballast, fluorescent lamps, and things like this. I'm really a layman about these things. but it's not for me, so I asked for help. The frequency is in the range of kilohertz, average 25 I guess...


texts: Desing Problem with Single Axis Solar Tracking System

texts:
I'm second year Electrical-Electronical Engineering student (It's Electrical Engineering basically but naming issues I guess) and my knowledge about circuits is limited to capacitors, inductors, resistors, basic diodes element-wise and simple circuit analysis using KVL-KCL and Terminal Relations.

TL;DR: I have been getting circuit lessons for the past 2 months, so I am not that knowledgeable about circuits (not considering high school experince).

Anyways, let me describe my problem. Here's my desing so far:

Edit: I forgot to connect DC Supplies to U4. Assume there are.

Notes: U6 detects higher of V2 or V3 and outputs a voltage to change the position of SPDT relay which in return activates Q1 or Q2 to by completing the connection between bases of Q1 or Q2. U5 detects if V1 is the highest or not. If not, SPST relay turns on. If V1 is the highest then SPST relay should disconnect the circuit rendering transistors as off. But the problem is if V1=Vhighest, comparator will behave unpreditibly. So for the time being I'm stuck here. I'll be analyzing the circuit as if U5 will work as I wanted then check if this schematic will do what I want. But I'm uploading revised desing before analysis to get feedback. Thanks for your help.

Let explain my design:

1- Sensing Unit

Positive DC voltage applied stationary LDR's used a light sensing units. Changing resistance values will create different voltage drops across LDR's thus voltage values will be used as inputs.

LDRs are near a point. They're angled wrt surface like this: \|/

2-Control Unit

a)Decision Subunit
This unit compares input voltages and gives highest input as output. This unit is incomplete and I'll be explaining what I want to and my question in a second.

b)Function Subunit
This unit generates a PWM wave that drives a PWM Servo Motor. As you can see this unit is also incomplete and I'll be asking about this too.

Now, my need:

I need to obtain 3 different Square waves each input. For this purpose I tried using transistor as swicthes. When base voltage meets a criteria it'll turn on, thus changing the duty cycle. (So I want 3 states: Q1-2:off, Q1:on Q2:off, Q1:off Q2:on) But I don't know how I can turn my Vhighest information to a controlling information for transistors' on/off states?

I thought that if I can compare this Vhighest value with V1, V2 and V3 and find out which one it equals to, then find my way from there but I don't know how I can do it, if this method even sounds plausible. So I need advice about how to complete the incomplete parts of my desing, basically.

Notes: If you need further information about project, I can give you this: 3 different PWMs are required for obtaining 3 different states from a motor. If V1 is the highest I need a specific PWM which indicates that light intensity at LDR1 is the highest and changes the angle of motor to a specific value. If V2 is highest then I need another specific PWM and the same for V3.

Also this circuit should completely be analog. Please feel free to inform me if my problem is not clear.

Another Note: The elements that can be used are limited with LDRs,LEDs, resistor, diodes, capacitor, inductors,op-amps, transistors and servo motor without encoders(don't know what that is)

More notes: Thanks to @Trevor, I have found out that my pulse generator is incorrect. I'll be changing that part of my desing in a day or two but please feel free to give advice until then.


texts:
I want to control a relay RSB1A120BDS that works on 24V DC using my Arduino. But, my power source that I use for other parts is 41V AC connected to a bridge rectifier. So my idea was to put a resistor in series with the relay coil to get the right voltage. This is a bit my setup:

simulate this circuit – Schematic created using CircuitLab

The transistor is a TIP 120 STM NPN-Darlington TO-220 60V 5A 65W. (I know now MOSFETs are better for switching, but I didn't know that when I bought the transistors) I added a 220Ω resistor, because I read somewhere that this is necessary to limit current. I measure 3.27 V over R2 and 1.37 V between the base and the emitter. So we have 3.27 / 220 * 1000 = 15 mA base current.

The datasheet says the average resistance of the relay coil is 1440 ohm and the rated operational voltage is between 19.2 V and 26.4 V. So then by using a resistor of 1 kΩ, the voltage over the relay coil should be 41 * 1440 / (1440 + 1000) = 24 and that should be alright.

The flyback diode is a 1N4001 50V 1A. It removed it and measured it with my multimeter, and it seems to be working. (low resistance one way, very high resistance the other way)

However, it didn't work. When I turn the transistor on, sometimes I measure 23.7 V over the relay coil, but most of the time I measure 0 V, and all 41 V are over R1. So maybe the relay coil is short circuited. I also hear a sound sometimes while I'm working with the multi meter, I think the realy is turning on and off. I thought maybe the issue is that I use pulsed DC instead of normal DC, and the peak voltage of 24 * sqrt(2) = 34 is too high. But this answer says that shouldn't be a problem.

A thing is that 26.4 / 19.2 = 1.375 < 1.4 = sqrt(2). So I can never pick a resistor R1 to keep both the peak voltage and the RMS within the rated operational voltage limits, but almost though.

The relay makes a sound when I touch it with scissors. See this video.

When I try the simpler circuit below (same diode and relay, different but same type resistor), it does work as expected. No noise when I touch it with the scissors.

simulate this circuit

What is the problem here?


texts: Can noisy USB traces slow down USB communication?

texts: Does USB slow down when there is too much noise, or does it simply fail? The USB host driver I'm using is ehci-hcd on Linux.


texts:
I want to make a Sallen & Key 2nd-Order Butterworth highpass filter with a defined gain. Let's say gain is +6 db.

Then,
R3 = R4 = 1 kOhm
F = 1000 Hz
C = 100 nF
R2 = 2 * Q / ( 2 * 3.14 * F * C )
Now, I would assume that Q = 1 / ( 3 - A), where A = 1 + R3 / R4.
But this table here doesn't agree.

What am i missing?


texts: How did wireless telegraphy reach so far?

texts:
Even as far back as the early 1900s, telegrams transmitted wirelessly could reach hundreds of miles. For instance, the Titanic communicated with Canada, 400 miles away, with relatively low-powered equipment. Given that telegraphs are very simple, how could these pulses have traveled so far?

And would these pulses still travel that far today with the same equipment?

And doesn't this mean that there couldn't have been very many people using the systems, since operators within hundreds of miles would all be jamming the airwaves? It seems this would produce a lot of cross-talk. Or were there multiple frequencies available for wireless telegraphy?


texts: 7-seg. Display Multiplexing Disturbing Real-Time Clock

texts:
One of my colleagues is designing a digital clock with 7-seg displays. The clock function is shouldered by a Real-Time Clock IC, PCF8563.

The RTC IC is clocked with a 32.768kHz crystal and its external caps (one cap is a fixed one and the other one is a trimmer for frequency trimming). The trimming is guaranteed by measuring 1Hz output (test frequency) function of the RTC IC using a precision counter/frequency meter. By the way, the communication protocol between MCU and the RTC IC is I²C with a speed of 400kHz.

Instead of using 7-seg display modules (like this one), he decided to use discrete 0603 case SMD LEDs for 7-seg display effect (this is important) and cost-effectiveness. He placed these LEDs on one side of the PCB, and the other side is full of other components (i.e. regulator, MCU, backup battery, RTC IC, driver ICs etc). The PCB is made from 1.6mm FR4 material.

PROBLEM

The displays are multiplexed with a frequency of 100Hz (min). Before the LEDs light up, test frequency measured from RTC IC's output can be trimmed to 1.00000Hz. But, once the MCU starts multiplexing the LEDs, test frequency shifts to 1.5Hz or even 2.5Hz and stays unstable.

TRIAL & ERRORS

Grounding the crystal's outer metal case, adding ground areas, adjusting multiplexing frequency did not work. It's quite interesting that using 7-seg display modules or separating RTC IC and its external components (i.e. crystal and caps) to another PCB does not cause any problem(s).

QUESTION

Despite using a separate PCB for the RTC block or using 7-seg display modules solves all the problems, he is restricted with using only one PCB housing all the components. So, what can cause this frequency shifting problem? What should be done to deal with this?


texts:
I am trying now to implement Hbridge using 2*p-2*n mosfet "ZXMHC6A07T8
" from zetex semiconductor  , I used the offered spice model and I connected simply as

and I connected to two PWM

what I do not understand is why the behaviour of the output in in between 9 and 9.6 and look like

What should be done to my circuit to get an appropriate behaviour?
Is it possible to add gate driver for my circuit? if yes how can I decide which gate driver is acting good with my circuit? what is the parameters of choose

PIN 6 and 8 are the output


texts: Resolution gain in Delta-Sigma Converters

texts:
Suppose I have a two bit quantizer with the following voltage levels: [0 0.2 0.4 0.6]. Thus 0V corresponds to bits 00 and 0.6 to bits 11. Suppose I use this quantizer in a first order delta sigma loop with a simple integrator y[n] = x[n] + y[n-1], if I use a DC input signal, say 0.25V, I will hit codes 0.2V and 0.4V with certain frequency. Hence after averaging this delta sigma ADC would work better than normal averaging ADC in terms of resolution.
In normal averaging ADC, the quantizer would only hit the code 0.2 V and averaging the values will have no effect on the resolution of the ADC.
Can we know how much resolution improvement is done by the SD ADC in this case? I am a little new to ADC's so I might have missed certain information, but all I really want to know is how much better the SD ADC works as compared to normal averaging ADC for a DC input signal in terms of resolution.
EDIT: Can someone explain how would we calculate the resolution of SD ADC in this case in time domain?


texts: Flip flop/latch with isolated differential input and differential output

texts:
I am looking to make something that takes a pulse of floating voltage (say from a feedback coil of on a transformer), and maintain a differential output voltage depending on the sign of the amplitude of the pulse. Then when another pulse comes along with a different sign, the output would change signs as well. I naturally looked into flip flops/latches, but after some experimentation and closer reading, I realized they do not really provide a differential output, and they do not seem to work with floating inputs. They seem to work instead with pulses of non-floating voltages and send a high to one of two nand/nor gates.

In summery: My problem is I am given an isolated voltage in the form of a pulse. I want something that will "remember" the sign of that pulse in the form of a voltage difference between two output leads.

The reason I emphasize the "differential" part is that the two output leads of a flip flop/latch will not form a complete circuit when connected through a load or something that senses voltage differences. It is just an open switch and a closed switch.

I may just be doing this wrong, or misunderstanding, but based on what I have tried, this seems to be nontrivial.


texts: Harmonic detection using lock-in amplifier

texts: Can a third harmonic of a signal be detected using a lock-in amplifier under the same parameters fixed for collecting the fundamental or the parameters needs to be adjusted.Here by parameters I mean sensitivity , time constant and phase. I am using a Mach-zehnder interferometer to intensity modulate my laser beam which is pulsed at 80 Mhz rep rate. The beam is modulated at 1.2 MHz. One arm of the interferometer is used for reference to lock-in which is stanford 865a. other arm is used for sample excitation. I am trying to extract the harmonics just by choosing the harmonics on the lock-in. The fundamental signal and the second harmonic are relatively easy to extract but even at inexorbitant powers i have not been able to see a stable phase for third harmonic.


texts: Circuit model, microcontroller to peripheral bus wire

texts:
For my project I have to connect a IMU sensor via SPI with a Cortex M4 microcontroller (Teensy 3.6). The sensor has to be about 0.5m apart so I will probably have to add some extras to deal with the longer than normal wires.

Ideally I would like to calculate/simulate my bus before soldering everything. I made a LTSpice model to simulate the behaviour of a 1MHz square wave (see bellow). What I'm not sure is if I have modeled the input of uC and Sensor correctly (as it is now the uC would just float high). From the datasheets I could only gather that the uC has a capacitance of 7pF on it's digital pins and the IMU (MPU9250) 10pF. So I added two capacitors as shown in the schematic bellow. Additionally the IMU breakout board has a 10k pull up.
What I could not find is if there is a second internally pull-up that I'm missing.

I want to use the simulation to get a sense to where I can adjust my components to stay within rise time margins and avoid transmission line effects by adding a low-pass filter if necessary.

I'd appreciate any feedback on this.


texts:
I am making a battery bank for portable LED projects. The battery bank has a 5V 12A (60W) DC to DC converter DDR-60L-5. I would like to add some extra (nice to have) USB Female plugs to this battery box for any USB device that I might need in the future.

I assumed I could connect the USB 5V(+) to DDR-60L-5 5V(+) and USB GND(-) to DDR-60L-5 GND(-) and that would be all that is required.

After reading this article How do I design a 2A or more power supply for my consumer USB devices? I found that I need a resistor network to tell the devices to use more current. After watching this video about Building the ultimate USB power distribution system I am worried about protection per port of the UBS charging. Reading this article I am told that I need to add filtering-caps between Vcc and GND. I am now a little overwhelmed with all the things I SHOULD do.

My question is:

Is there an existing IC that I can use to add all the protections, high charging current, etc.. to a USB charging port?
What is the absolute minimum I can safely do to create a simple USB charger port?

Edit: I am using this power bank to power 5V LEDs strips, 12v LEDs strips and other electronics projects. The USB charging port is a 'nice to have' since I already have 5V available in the battery pack.

simulate this circuit – Schematic created using CircuitLab


texts: Does the combined  input IP3 of the LNA+Attenuator change with the attenuator setting  if the attenuator is placed after the LNA?


texts:
I was wondering what granularity means? It is used in the context of:

  A background task that performs a simple operation. The granularity of the background task, specifying the number of calculations performed for each activation, is passed as a parameter


texts:
Good morning,

I am trying to work on some home improvement DIY projects and trying to control light from an RPi / Arduino using USB connection. I've found two possible products, that I think might suit me:

http://www.sainsmart.com/8-channel-dc-5v-relay-module-for-arduino-pic-arm-dsp-avr-msp430-ttl-logic.html

or

http://www.amazon.com/gp/product/B0093Y89DE/ref=pd_lpo_sbs_dp_ss_1?pf_rd_p=1944687622&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=B004JWW1GQ&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=1QWFW0X2KN49TCBWJW0K#product-description-iframe.

However, I was not really sure how to exactly read the specs for the relays that are given on each website. The light that I am trying to control are going to operating at 12V drawing around 5A (60W bulbs). The specs that are given are:

Relay specification: 10A 250VAC/10A 125VAC/10A 30VDC /10A 28VDC
Power Supply: 12 VDC
Current consumption: 300 mA

Thus I wanted to ask if somebody could enlighten me what the first line "Relay specification" means? Would it be able to handle 5A / 12V bulbs that I would want to connect to it?

Thank you very much to everybody.


texts: What are effects of attaching more antennas to Wi-Fi router via RP-SMA splitter

texts:
Theoretically and practically speaking what are effects if in typical Wi-Fi router attach more than one antenna per output using something like RP-SMA Splitter and or extension cable ?

In my case, Asus AC66U 802.11ac Dual-Band; 2 chips(bgn, an + ac) connected to each 3 antennas. MIMO: 3x3:3


texts: What lubricant is suitable for switch contact?

texts:
I have this expensive DPDT switch (20A 250V 2hp) which the only problem is dirty encumbered inside. The encumbrance is made of carbonized material and some kind of wax and dirty electrical contacts. The contact poles are in good shape after a good cleanup. I cleaned all part thoroughly. Now it all look clean and neat, ready to reassemble the switch. Since, originally, there was some lubricant inside, that looked like some kind of wax, I am on the search for a similar product.

I recently dipped contacts on a relay (2HP motor) with high temperature silicon grease called Dielectric Grease 67VR. My repair lasted about 3 days (perhaps 20 ON/OFF cycles). The contacts ended up welded together and the grease was carbonated. So, obviously, the dielectric grease is Not a good option.

The Question: What kind of lubricant would be suitable in my switch so it does not end up being a disaster but rather a successful repair ?


texts: I have about 100 of these very small diodes, approximately 1/3 smaller than the diameter of a dime. They are all umarked and all I know is that their voltage drop is about .55v to .62v. I am thinking they are silicon based diodes, but I am not for sure. Any ideas? Thanks.


texts: draw out as frequency divider from circuit

texts:
I have this circuit and I have to get the out "S" but have no idea how The initial condition is D0 and Q1 = 0

And i just have what I guess is q0, and with that i supposse S is 0 and then all 1, but not sure.

I hope you can help me. Thanks.


texts:
We live in a moderately sunny place. We do get some cloudy days frequently. I have seen the output to go above 24V(like25V) on a fully sunny day middle of the day which means lots of days the solar output might not be enough to charge the 24Volt battery pack.
My solar panel setup has (2  * 12V 100W in series  and 2 * 24V 100W in parallel). And both connected in parallel) to produce that output(400W). Is there a solution to generate more consistently 24V in a moderately sunny place?
The issue I have is that with 22-24V output lots of the the days, it is not good enough to drive charge into my battery pack/inverter(minimum requires 24V). What will the right solution for making sure that I can generate more than 24V even on cloudy days?


texts: Why the Wien Oscillator output is a sine?

texts:
I don't understand why the output signal of the Wien oscillator is a sinusoidal waveform.

I can easily understand how a sine waveform can be generated by an oscillator which contains an LC circuit (such as the Colpitts oscillator) or by a square waveform generator with a low-pass filter.

But for the Wien Bridge (like the following scheme) I don't understand the physical mechanism of generation of the sine.

The only thing that I think when I see this circuit is that it seems quite similar to the astable multivibrator with an Op-Amp (except for the capacitor in the positive feedback and the resistor R between the + input and GND), which generates a square waveform. Does this capacitor in the positive feedback make the difference?


texts: How to find the half-bridge MOSFET Cstray for LLC half-bridge converter?

texts:
I am designing an LLC half-bridge converter for the 1st time.
Everything seems fine according to the AN2450 from ST from which I am making an excel sheet.
I need Czvs to complete some formulas. However, Czvs = Cstary + 2·Coss. The Coss is found according to the MOSFET datasheet, but I do not know how to find Cstray to calculate Czvs.


texts: Is it possible to amplify near zero signals?

texts:
Is there an amplifier has an ability to amplify any signal down to -500 dBm?

If there is not, can it be possible?

If it is not possible, what is the weakest ever signal that can be amplified?


texts: Why are flash memory chips commonly packaged in Type I TSOPs?

texts:
While available in many sizes, the presence of a Type I (pins on the short sides) TSOP is a clear indicator of a flash chip in a typical embedded system.

Is there a technical reason for the manufacturers to use Type I over Type II (pins on the long sides), or it is just that they are making compatible versions of the first available chips?

Why is it different for SDRAM, which generally has pins on the long side?

UPDATE: I clarified that I am asking about the preference of Type I TSOP over Type II TSOP. Added SDRAM reference.


texts: I am failing to understand the difference in Impulse Sparkover voltage vs DC Sparkover voltage of GDT

texts:
Lets say I want to use a Gas Discharge tube for indirect lightning protection, and I have a tvs diode in parallel with GDT. Since this is indirect lightning and has a fast waveform, should the tvs diode be slightly above the Impulse Sparkover voltage? Or can I just have tvs diode above the DC sparkover voltage?

I know that Impulse Sparkover applies for fast surge waveform, and a DC sparkover applies for a slow waveform in second.

If I were to choose a tvs clamping voltage slightly above the Impulse Sparkover voltage, wouldn't that already destroy the equipment the I am protecting due to high voltage. Impulse sparkover voltage are usually around 200V-600V.

Also which is more dangerous or destructive - equipment destroyed from high voltage or equipment destroyed from high current?


texts: Measuring noise figure of a microwave radio receiver

texts:
As part of college assignments, I've been asked to explain in detail how certain parameters - informed by the product's manufacturer - of a specific microwave radio system can be measured. Among these parameters, is the receiver's noise figure.
Now, I've proposed a measurement diagram like this (from maximintegrated):

Nevertheless, I've been told that this method has a problem, which is that as my DUT is a receiver, it performs demodulation of the microwave input signal and therefore the frequency found at the input of the DUT is different from the one found at the output - I fail to see why this is a problem for this measurement.-

Anyway, the "tip" I was given was to look for the method used by the manufacturer, or the standard applied. Unfortunately, it seems that this information is not provided in the technical description, which I provide below.

Then what I would like to know is how can I overcome this problem of different frequencies at the input/output of the DUT (is it really a problem???) to perform the required measurement.

Link to technical description:
Technical description

It's a long document but I believe that the only relevant information in this matter is on page 49, section 8.2.6 "Noise Figure"; and section 7.2 page 39 "Reference Points" which clarifies the points between which the noise figure was measured.

Please note that although I've found related questions to this topic, I could not find any information concerning the frequencies problem I described before.

I will appreciate any help, thanks in advance!


texts:
I am trying to modify a Roland SVC-350 that is currently configured for 240V power to run on 120V.  I ran into some questions as I was speccing out the transformer that I needed.  The full schematic can be found here, but the relevant section is here:

note: The OP-143 fuseboard shown just uses a different cap/fuse combo for the different voltage configurations.  Capacitance is the same across all versions (only the voltage rating changes) so I should only need to swap out for the fuse.

The closest thing I could find to a datasheet for the TA7179p is here.

My first thought was that a 120V:35VCT transformer would work fine, as it should generate the spec'd 18V RMS with respect to the center tap.  However, the +/- 22V spec doesn't make sense to me.  If it's rectified voltage it should be around 16.2 VDC with maybe +/- ~1V of ripple based on the power rating of 8W for the device and those 1000uF caps, minus a diode drop.  I don't think it's peak voltage either, as that should be closer to 25V (minus a diode drop) if my understanding is correct.

I admit that I'm not entirely sure the what the function of those two transistors is, though I imagine it's just to act as a current source so the regulator doesn't have to work as hard.  They're connected via jumpers and bolted to the frame so I assume they're expected to dissipate a fair amount of power.

My concern is the regulator itself appears to require a dropout of at least 2V, and is designed to work at 20V.  So, I'm inclined to believe that I'd need more than 18V RMS to have enough room above 15V after rectification.  The next "standard" transformer size of 48VCT would lead to +/- 24V RMS.  Those peak voltages get pretty uncomfortably close to the 35V spec on the 1000uF caps though.

So, I see a couple options:

Just use a 36VCT transformer and trust the spec
Use a 48VCT transformer and replace the 1000uF caps with 50V rated ones
Get a more expensive 44VCT transformer (It's $25 vs $10, so it's not a huge deal, but I want to be sure it's the best option)
Say f*** it, cut a bunch of traces, and just replace that TA7179 with a 7815/7915 pair.  I'd rather not mess with a circuit board on a piece of "vintage" equipment, but...


texts: Hello iam a bit stumped with this i have 2 mcu's both MSP432E on the same pcb.I only have one ethernet port but need both MCU's to be connected to the one ethernet port.Can i simply have 2 ethernet transformers,and connect the media side together with there like pins connect so tranformer 1 RX+ pin would have a trace going to transformer 2 RX+ pin?What would be the correct way going about what iam trying to accomplish?Thanks


texts: Is it possible to tell the frequency of the noise in this case?

texts:
I have a scope screen shot from a while ago and Im not able to generate another test.

What can we say about the frequency of the ringing pulse noise by looking at this scope screen?


texts: How to define a primitive device in Proteus?

texts:
I'm trying to make my own full adder and some other devices as a sub-circuit in "Proteus" and use them several times in a bigger circuit.

The problem is when you copy a sub-circuit you need to rename all of its inner parts, otherwise, the parts with a same name in two sub-circuits would be considered as one, therefore you'd get some errors.

So I'd like to know if there is a way to define a full adder of my own and use it like "74LS183" which is a primitive device, and by primitive I mean it has been defined in the library.


texts: What is the purpose of op-amp in the output of Instrumentation amplifier

texts:
I encountered a problem while solving an analog circuit.
I just need to know the purpose of the last op-amp (K4) at this circuit:

while solving I understand it just amplify the output voltage from the Instrumentation Amplifier, but there is known purpose for it beside to amplify Vout3.

thanks!


texts:
I've been spec'd a MID400 in a high voltage A/C power monitor circuit. After receiving the prototype (board is done), I've determined this device is for power on/off application. Problem is I need to detect brown out conditions where service voltage is below an acceptable value. EXAMPLE 240VAC 1/PH application. Anything less than 180VAC needs to trigger an alarm.

MID400 spec sheet states current > 4mA = "Saturated" mode and <.15mA = "Off" mode. Spec sheet also calls out a condition called "unsaturated", which is current between the 4mA and .15mA. Spec sheet states "Under these conditions the device makes an attractive, simple 120Hz clock generator that is free from most of the normal power line transients for many digital applications."

My thinking is to monitor the output of the MID400 via microcontroller analog configuration and increase dropping resistor to create a acceptable voltage range (EX:510kΩ in 240VAC application) thus operating the MID400 in unsaturated mode and use the analog configuration to detect brown out and brown out return.

I have been in contact with MID400 mfg to ask what their design requirements (current threshold) are to attain this "attractive clock generator" feature. They have been of no help. My testing shows no consistency regarding current and 120Hz. Very random results per individual MID400.

I am trying to salvage this project but am nearing the point of restarting. Anyone have any input on MID400 "unsaturated" mode? Experience or suggestions?

https://www.fairchildsemi.com/application-notes/AN/AN-3007.pdf


texts: Desoldering a through hole capacitor with weird terminals

texts:
Apologies in advance if this is the wrong place to post this question.

So I've just RGB modded an old CRT TV, and now I'm trying to replace a series of capacitors to hopefully fix some screen geometry issues, and I've run into a little road block on a few of the larger high-voltage ones. The terminals on the underside have some sort of star-shaped grip that I've never seen before, and can't figure out how to detach them. I've been able to get some of the solder off with my vacuum desoldering gun, but I can't quite figure out the gripper part.

The replacements I bought on DigiKey (same capacitance/voltage rating, but the terminals are just thick stumps) don't have these, so I'm at a bit of a loss. Has anyone seen anything like this before? Thank you for your help.


texts:
I have a DFN component with a thermal pad underneath. On the other side of the PCB, I need to place a few other components thus leaving me with very little freedom in placing the ground vias on the thermal pad.
Is it fine if I place the vias irregularly (somewhat as shown in the picture below)?

What trouble could I be facing for doing this?
Thanks!


texts:
I have a code where I have 2 functions:

1 - read_loadcell - which reads 5 HX711 (5 load cells)

2 - rpm_read - which is supposed to read rpm's using an inductive sensor. Basically I have a metallic wheel which has 4 symmetric holes in it. Each time when a whole is under the sensor I get pin in high state.

Now my issue:

If I run in loop() only "read_loadcell" is working fine.
If I run in loop() only "rpm_read" also working fine.
The issue is that if i run both of them, the rpm don t work anymore

So the question is how can i have them both working?

#include "HX711.h"

HX711 scale_GS1(A1, A0);
HX711 scale_GS2(A3, A2);
HX711 scale_GS3(13, 12);
HX711 scale_GS4(11, 10);
HX711 scale_FS(9, 8);

float gs1 = 0, gs2 = 0, gs3 = 0,gs4 = 0, fs = 0;

// read RPM

volatile int rpmcount = 0;
int rpm = 0;
unsigned long lastmillis = 0;

void setup() {
  attachInterrupt(0, rpm_fan, RISING);//interrupt cero (0) is on pin two(2).

  Serial.begin(9600);   //start serial communication

  Serial.println();  Serial.println();  Serial.println();
  Serial.println("/////     WELCOME     ///////");
  Serial.println();

  //set scales
  scale_GS1.set_scale(1324);
  scale_GS1.tare();

  scale_GS2.set_scale(1324);
  scale_GS2.tare();

  scale_GS3.set_scale(1324);
  scale_GS3.tare();

  scale_GS4.set_scale(1324);
  scale_GS4.tare();

  scale_FS.set_scale(1324);
  scale_FS.tare();

  Serial.println("Readings:");
}

void loop() {

rpm_read();

read_loadcell();

}

void rpm_fan(){ /* this code will be executed every time the interrupt 0 (pin2) gets high.*/
  rpmcount++;
}

void rpm_read(){
  if (millis() - lastmillis == 1000){  /*Uptade every one second, this will be equal to reading frecuency (Hz).*/

 detachInterrupt(0);    //Disable interrupt when calculating

 rpm = rpmcount * 15;  /* Convert frecuency to RPM, note: this works for one interruption per full rotation. For two interrups per full rotation use rpmcount * 30.*/

 Serial.print("RPM =\t"); //print the word "RPM" and tab.
 Serial.println(rpm); // print the rpm value.

 rpmcount = 0; // Restart the RPM counter
 lastmillis = millis(); // Uptade lasmillis
 attachInterrupt(0, rpm_fan, RISING); //enable interrupt
  }
}

void read_loadcell(){

  scale_GS1.power_up();
  gs1 = scale_GS1.get_units();
  scale_GS1.power_down();

  scale_GS2.power_up();
  gs2 = scale_GS2.get_units();
  scale_GS2.power_down();

  scale_GS3.power_up();
  gs3 = scale_GS3.get_units();
  scale_GS3.power_down();

  scale_GS4.power_up();
  gs4 = scale_GS4.get_units();
  scale_GS4.power_down();

  scale_FS.power_up();
  fs = scale_FS.get_units();
  scale_FS.power_down();

  Serial.print("GS1 :\t");
  Serial.print(gs1);
  Serial.print("\t GS2 :\t");
  Serial.print(gs2);
  Serial.print("\t GS3 :\t");
  Serial.print(gs3);
  Serial.print("\t GS4 :\t");
  Serial.print(gs4);
  Serial.print("\t FS :\t");
  Serial.println(fs);
}


texts: How can voltage of a battery be calculated?

texts: If voltage is calculated using the formula V=IR, how can the voltage be calculated of a battery if it is not connected to anything (i.e. no current)? I am not 100% sure about this, but neither do I think there is a resistance. Thus, how can V be calculated when both I (current) and R (resistance) are unknown?


texts:
I am trying to power a 5v circuit from any voltage between 100-240v. I know it is possible to do this with a transformerless power supply, but only for a single voltage (e.g. 120v only), but how do I make it work with the entire 100-240v range?

So if I power the circuit in the U.S. (120v) or Britain (230v), the circuit should still work.


texts: Air cooled heatsinks - horizontal or vertical fins?

texts: If we have a heat sink with fins, for example like this  how does the efficiency vary between horizontal and with the fins vertical in non forced air?


texts: checksum phase in the I2C model shown bellow for si7021

texts:
in the diagram shown bellow taken from Si7021 sensor datasheet shon bellow page 20.
we have a checksum stage.
I cant see where the LS Byte ends and where the checksum starts? the while 10 step is not clear to me with regarding of what going after what?
Thanks.
https://www.silabs.com/documents/public/data-sheets/Si7021-A20.pdf


texts:
I want to convert a generated PWM by a microcontroller to a 3-level voltage.

[]

the maximum output voltage range is between -5 to 5 or -10 to 10 volts. Another point that may well be considered is that there is an optocoupler after the MCU. Also My micro is availabe to drive 6 PWM outputs.
I tried push/pull but I didnt get any right answer.


texts:
When it is necessary to use an oscilloscope with isolated grounds?
For nearly 5 years now, I have been using oscilloscopes with a common ground. But I have no experience in using one with isolated ground.

The question popped when I was going through a spec-sheet for a DSO that the sales person had shared.


texts:
I see a few questions here casually mention that image sensor modules have a
"standard parallel digital video port (DVP) or ... MIPI high-speed serial interface"

"Where do I start with embedded video?"
"Processor with hardware camera interface port?"
"digital video port (DVP) parallel output interface MIPI serial input and output interface"

Is there a specific digital video port (DVP) interface standard?
Is there a specific MIPI standard?
If so, where can I get the details on the signals, standard connectors, etc.?
Or is "DVP" merely a generic term that includes a variety of interfaces such as DVI, DMP, HDMI, SDI, UDI, DVB-ASI, FireWire, i.LINK, DisplayPort, etc.?
Is there maybe more than one interface standard that (confusingly) has the same "DVP" initialism?
In particular, some people seem to think that it's possible to directly connect a 44 pin processor a DVP interface, so apparently they are not talking about the 100 wire SGI DVP interface -- are they perhaps some other DVP interface, or is this merely a typo for one of the above specific interfaces?


texts:
I am trying to compile a project and it takes a very long time to route. - ISE 14.3

In my main module, I am using a package where I have declared an array of constants. These constants use functions that I have declared in another package.

As far as I know, the synthesis tool precomputes these contant values and stores them as a LUT or block RAM before synthesis.

But I am wondering if using this package is creating routing issues.

The constant package looks like this:

the function real_to_sfixed is defined in a fixed point library that in turn calls few more functions

the table is used as:


texts: Instrumentation Amplifier Gain set resistors

texts:
We are looking for Instrumentation Amplifiers for an application.  At this stage, we have decided a certain gain value for our Instrumentation Amplifier. The datasheet of the product mentions the very precise value of gain resistors to attain certain gain value. We haven't ordered the products yet as I am confused about whether we will be able to acquire the gain resistors ourselves (from some other manufactures) or they will come with the Instrumentation Amplifier package we will order?  Because these gain resistor values for certain gain sets are very precise which are difficult to get from manufactures. I am attaching the screenshot of AD8237 gain resistors from the datasheet as a reference.
https://www.analog.com/media/en/technical-documentation/data-sheets/AD8237.pdf


texts:
In class, we were given equations for the transformer in terms of number of turns primary/secondary and coupling coefficient K, however effect of distance between coils, presence/absence of core, and composition of core were not covered.

Of particular interest: What is the equation for 2 parallel straight wires? Clearly turn ratio is 1:1, but how to account for distance between the two?


texts: Protect soundsystem from GSM/GPRS pulsing noise sounds

texts: What is the best way to isolate soundsystem from an modem/cellphone to not hear pulsing noise sounds when GSM/GPRS communication is active.


texts:
This is making me think more than it should, I'm obviously missing something obvious.
I have a hydraulic power pack and the control unit has stopped working, I need a quick and simple circuit to bypass the control unit.
It can only be operated by one momentary SPDT switch.
There's a signal for right, left and motor.
To turn right you need to supply 24v to open and motor
To turn left you need to supply 24v to close and motor
Every time I think of a circuit that works, I then draw it and realise I will send power to both the open and close supply on both switch presses.
What circuit will make this work?


texts:
I have a handful of relays that I am working with for a project. I'm familiar with 4 pin relays, where there is a coil and switch,but the relays I am working with have 8 pins.

Here is the model# and data sheet

EC2-5NU https://www.mouser.com/ds/2/212/KEM_R7002_EC2_EE2-1104574.pdf

On page 3 there is a diagram, I have the Non-latch type on the left.

Pins 1&12 are for the coil, but the switch pins are a bit confusing to me.

It looks like 3-4 & 9-10 are normally closed, and 4-5 & 8-8 are normally open.

What is confusing me is why there are two sets of switch pins.


texts: Create small variations in voltage for opamp reference pin

texts:
Hello and thanks beforehand.

I'm designing a circuit to measure 4 wheatstone bridges using 4 Analog Devices AD8422 in-amps. Now, i'm feeding the AD8422 output to a 3.3V ADC, so i'm offsetting the output 1.65V in order to be able to measure the full scale output of the bridge. However i'm aware that tiny differences in the bridges, opamps and resistors will require slightly different offsets for every bridge (i'm expecting something like +-0.05V would do).

The AD8422 requires the reference to be fed from a low impedance source

Now, to create the 1.65V reference, i'm using a 3.3V source, a resistive voltage divider, and a Texas instrument's OPA333 as a voltage follower. However, to individually adjust every AD8422, I would need 4 of those circuits with potentiometers in the voltage divider, each one feeding into one AD8422. The boards that have the AD8422 are very small and integrating another opamp (even a SOT23 one like the OPA333) is pretty difficult (and expensive if we want to expand the system), so, here comes the question:

How would you apply small variations in a reference voltage without altering the low-impedance nature of the output?

I'm aware that the potentiometer aproach would not work, as you would need precise knowledge of the intensity going into the REF pin and pretty high resistances (2k+) which would be like a voltage divider.

Thanks for your help!

simulate this circuit – Schematic created using CircuitLab


texts: Dielectric absorption in capacitor (audio crossover)

texts:
I want to understand the selection of a proper capacitor type for a simple audio crossover (passive lowpass filter before woofer, passive highpass filter before the tweeter).

Various blogs more or less recommend foil capacitors because of their low ESR and their low dielectric absorption.
While I know that dielectric absorption is a concern for S&H circuits, where a DC voltage should be kept stable over time, I have no idea why it should be a concern for audio circuits operating somewhere between 20Hz and 20kHz (and not at DC). Isn´t dielectric absorption a purely DC related characteristic?

Can someone explain why dielectric absoption is a key characteristic when selecting a capacitor for a (passive component), audio crossover?


texts: How to calculate and measure motor constant for stepper motor?

texts:
I am working on a project using ST4118D30004 stepper motors and powerSTEP01 drivers.
The ST4118D30004 is a bipolar stepper motor with 4 wire connection.

While researching how to find the optimal settings for the driver I came across

  "Holding torque (T) is the product of a motor's torque constant (KT) and the current (i) applied to the stator windings."
  controleng.com Stepper motor torque basics

  "the k_t parameter is the motor torque constant which is equal to the k_e constant, but expressed in Nm/A instead of V/Hz"
  page 6 of PowerSTEP01 Voltage mode control operation and parameter optimization

as well as how to measure K_e by applying scope across a phase and turning it at constant speed, K_e is then supposedly the ratio of peakVoltage/frequency.

  "The \$k_e\$ is the coefficient that relates the motor speed to the BEMF amplitude. This value is not usually present on stepper motor datasheets, but it can be easily measured by means of an oscilloscope:

  Connect one of the motor phases to an oscilloscope channel
  Set the oscilloscope to the trigger value on the rising or falling edge of the channel and set the threshold value close to zero (few mV above or below zero)
  Turn the motor shaft. This can be done by hand or by means of another motor. The most important thing is to obtain a rotation speed as constant as possible
  Set oscilloscope time and voltage scales in order to display a sine wave during the motor rotation.

  If the rotor is turned by hand, the operations should be repeated until a good sine wave is obtained. A good sine wave keeps its amplitude constant for at least 2 or 3 cycles (Figure 7 and Figure 8). This operation might require several attempts.

  Measure the peak voltage to frequency ratio of the sine wave. The resulting value is the motor electric constant expressed in V/Hz."

  page 14 of PowerSTEP01 Voltage mode control operation and parameter optimization

calculating K_t from values given by specification by manufacturer of motor
holding torque T = 0.8 Nm  current i = 3 A
T/i = 0.8 Nm / 3 A = 0.267 Nm/A

Measuring K_e

2.55 V / 85.5 Hz = 0.0298 V/Hz = 0.00474 V/(rad/s)
5.55 V / 208 Hz = 0.0267 V/Hz = 0.00425 V/(rad/s)
7.00 V / 263 Hz = 0.0266 V/Hz = 0.00423 V/(rad/s)
11.1 V / 420 Hz = 0.0264 V/Hz = 0.00420 V/(rad/s)

About a factor 10 difference 0.267 Nm/A to 0.0266 V/Hz, why?

Addition 1: As mentioned in comments and also specified here http://www.spectrum-soft.com/news/spring2014/stepper_motor.shtm the K_e should be in V/(rad/s) not in Hz for K_t to equal K_e. This however actually means the difference in my results is a factor ~6.28 bigger does it not?

About a factor 60 difference 0.267 Nm/A to 0.00423 V/(rad/s), why?


texts: Can a feed wire also be used as a relay trigger?

texts:
Can I use a low voltage wire (10.5 V) as a supply AND trigger With a single pole double throw relay? Is there a solid state option available?
I need a way to switch power back and fourth to LED lights from one 12 V wire to a 10.5 V wire (dimming feature) but I would like the 10.5 V wire to activate the relay. Would I need diodes as well? The 10.5 V wire activates auto dimming for another component too.
I apologize for the crude schematic. lol


texts:
What is the relation between  the input and output current  of a generic efficient ( not just a zener diode) DC voltage stablizer ie:
If the input voltage  equals 15 V  the stabilized  voltage equals 12V  and the output current equals 2A whats the input current of the stabilizer? Does the input current decrease with input voltage ?


texts: Universal 3.3V & 5V power source for small device

texts:
I'm working on a hobby project which combines two modules that require 3.3V @ 130mA and 5V @ 100mA power sources. I want to make my device work at wide range of power sources - from single 3.7V battery up to 12V. So far I think to use step down regulator to get 3.3V and feed that to step up regulator to get 5V.

Is this a valid solution to my problem? Is it effective solution?


texts: Does my signal generator's ground need buffering?

texts:
I have an AD9833 signal generator (sorry I mislabeled it in the diagram as an AD9388) whose output is fed into a unity gain buffer, see picture below. The output is then passed into various materials to see how they react to signals.
What I'm confused about is the GNDac connection. Does this need buffering as well?


texts:
I have this power jack socket. I would like to connect wires to the terminals permanently and to have a stable connection. I searched for a connector that would fit with the terminals of the power socket but couldn’t find one. Is there a wire connector I could buy or what method would you suggest for connecting wires to the terminals?

link to the power jack socket I have


texts:
Project

The system is effectively a sensor network  that connects to a star topology routing network. The Identities of each node's identity must be kept secret from all listeners as the range of the RF transmission and relay may be on the order of tens of miles. Each sensor node has its own Identification number, as required by laws pertaining to our systems target deployment.

This means that if someone is able to read the identifier on the node then the security has not value, so a side channel attack on our implementation is a waste of time, unless they can implement it from a long distance, but I do not believe our SPI will radiate that well when sandwiched between a power and ground layer.

Security Options

This question is asking for solutions to using AES-128. I will explain what I found in an answer that I was lead to directly by Joby Taffey. Thank you Joby. I was looking for off-chip low cost solutions that could speed up our system greatly, it ends up i missed something from my chip supplier.


texts: Choosing an FPGA based on ADC sampling rate

texts:
I have a project involving an ADC sampling at 500 MHz. I need to take this ADC data and boil it down into something a cheap CPU can process. I believe this is a good application for a low-grade FPGA, so I am trying to understand how best to approach selecting a specific FPGA device.

The math involved in the FPGA will be minimal. Basically, I need the 500 MHz sampling speed to capture the physical event, but the FPGA will be selectively discarding most of the samples. So I don't think I care about how many LUTs, cells, or RAM bits the FPGA has. I need relatively fast I/O, and I need it to be cheap.

How can I tell if one of the cheap FPGAs (example: Spartan-6) I'm looking at is fast enough to keep up with my ADC? For the purposes of the this question, assume the ADC has an LVDS connection. Two ADC chips I am considering are the AD9434 and the ADS5403. I'm trying to understand the minimum requirements to interface with an ADC of this caliber.

What dictates the limit on an FPGA's I/O communication speed?

What are the key datasheet parameters I should be paying attention to when looking for an appropriate part?

Note that this is an embedded application, so stringing together some dev boards can be effective to prove out chip performance, but ultimately this will be a custom design.

Also note that the final sampling speed for future work may differ, so I am interested in understanding and comparing key I/O parameters between FPGAs in general. Other applications may require 250MHz sampling, or 1GHz, or 1.5GHz. I want to understand the FPGA I/O bottlenecks so I can choose a cost-effective FPGA for whatever sampling speed may be required.


texts: Wireless power transfer efficiency calculation

texts:
So I'm looking into retrofitting a Qi transmit eval and receive eval kit with coils of a larger diameter than the stock ones, then looking at what playing with the separation will afford me for my theoretical use-case (I would be exceeding the recommended Qi 5mm max sep). To clarify, I understand I may be taking them out of the Qi specs for now and that's fine for the purpose of my study. Starting with this stack exchange discussions:

Is the QI norm about the components or the coil?

and

How big does my wireless charging coil need to be?

I thought I could in theory, take the field generated by the Tx'er Bt(z=0), then that received by the Rx'er Br(z), solve them for current, then take the ratio of received to transmitted current multiplied by the required voltage ratio and get the required power ratio to calculate efficiency. This would give me the variables of the separation of the coils 'z' and their associated radii directly influencing the efficiency (power ratio), but the numbers don't make sense. Have I made a gross oversimplification or is my logic not valid outright?
Thanks in advance for any insight or any pointers on a direction I should go from here,
b


texts:
My question is, how are cell phones bale to produce on the fly video like mp4?
Are they using a hardware encoder chip?

Because most of them run on ARM chips? Are there ARM chips that can handle the encoding of the video on the software side?

If there are using hardware video encoders, what are they?
Are there hardware video encoders for the hardware enthusiast and diy to try and play with them?


texts: Why did spilled coca-cola on a terminal strip cause this odd voltage problem?

texts: I recently repaired a vending machine that had coca-cola spilled on a terminal strip. A 9.5V source from the strip measured correctly on a DMM when there was no load on it but dropped to 2V with its normal load (less than 1 amp). Cleaning the strip of hardened cola fixed the issue. There was corrrosion damage noted after cleaning. Why would the 9.5 volts behave this way? (I know cola is corrosive).


texts: Need help for troubelshooting a modification to a reverb circuit on a guitar amp to an FX loop circuit

texts:
Sorry if I am redundant here. I am totally new to this type of site so I apologize in advance. I found a similar question on the site but I didn't know if it was still active and I think my question is actually a bit more specific.
So here it is. I have a Fender Frontman 25R and I would like to use the reverb send and return as an effect loop instead. I don't mind getting rid of the reverb tamk of the amp. So I found the schematic of the amp and here is the area of interest:

As you can see, R42 adjusts the reverb level and I would like to keep it for my general effect level. Note that P13,14,15 and 16 are not connected. On P17 and 18, I used the wire going to the point with a dash on top as the sleeve of a 1/4 jack plug, P17 for the send jack and P18 for the return jack.
I made a little bit of research and found an article discussing the topic. The writer gives the following schematic and explanation:

Simple, right? So, I was happy and thought my problem was solved. I made the little circuit, correcting what looks to me like a mistake (J1 sleeve goes to J2 tip in figure 2, which does not make sense to me but feel free to correct me if I am wrong...) and it... kind of work. I can plug a pedal in the then created loop but I have to push the level on the pedal and even then, the effect is not that much present even with R42 on 10. Plus, it changes the sound in an unpleasant way (thin and trebly) and add quite a bit of noise to it as well. If I unplug the pedal, the sound goes back to normal.
Does anyone have an idea on how to fix this? I was thinking about an impedance or a signal level issue. If needed, I also have the reverb unit model number and specification document.


texts: Hello everyone i'm working on a project of pwm command using simulink,but i'm stuck in this error "Undefined function 'etapar' for input arguments of type 'cell'" any solutions please??


texts: PSRR and CMRR in a diffferential amplifier

texts:
Please, can anyone help me how to find the PSRR and CMRR in this simple differential amplifier circuit as shown below in figure 1?

I have searched on the internet and I decided to follow this methodology to find it:

First of all, I calculate the differential gain of the amplifier (the figure 1) which is for a single-ended output 4.510 (so for differential output is 9.021) as shown in figure 2.

After this step, I apply an ac voltage source in series with the DC supply voltage (1.2V) of the circuit, to insert the supply noise.Also in the transistor, I apply only dc voltage values.Again I measure the gain which is very small for single ended output:7.58*10^-6 (I have named this gain as Asupply.Also a differential output does not make sense because Asupply is zero) as shown in figure 4.

So the PSRR = Adm / Asupply = 9.020 / 7.58*10^-6 = 1.189*10^6

PSRRdB =20log(PSRR) = 20log (1.189*10^6 ) = 121dB

Because I am little trouble can someone advise me if the methodology that I follow is correct? My result for PSRR is correct? Am I doing something wrong?

Furthermore, I insert a mismatch between W (W=1um right hand and W=2um left hand)of the input transistor to become more realistic the circuit and my schematic become as shown in figure 7 and results is in figure 8.

Also, I try to calculate the CMRR of the amplifier.We know from figure 1,2 that the differential gain is 9.021. To find the CMRR I follow these steps. First of all as shown in figure 5 I apply the same input in the input transistors and calculate the gain as shown in figure 6.So

CMRR = Adm / Acm = (9.021/3.11*10^-6) = 2.9 *10^6
CMRRdB = 20log(2.9 *10^6) = 129dB

Is this result correct for CMRR?

Thanks in advance

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8


texts:
I have built an electronic circuit that connects to a 5V power supply. The power supply does get a bit warm when the circuit is operational. The supply is cooled using air convection method.

Will buying a 12V dc fan help to cool down the supply? If not what can I use that will not break my wallet.

Is there a criterion to follow when selecting an electromechanical cooling system i.e. cooling fan.?

The power supply is a Meanwell RS-15. The circuit pulls about 1.8A.


texts:
I live in a rural area.

A problem occured when my UPS could not run my computer simply because of voltage fluctuations. I have tried many stabilizers but its too rapid that it would make a tick and the UPS would switch to battery then on line after some time it would run out of juice and just decide to shut off.

I now have many stabilizers but none worked. the last fix I can think of is the cap/ throttle the outlet voltage to 100-110 depending the minimum its fluctuating from so the stabilizer won't tick and the UPS neither hence running all day long.

TL;DR: How to Cap / throttle the output voltage a wall outlet to stop stablizer from making a tick, hence running the UPS on line. ANY way even bringing an electrician and do what's described in the answer.


texts:
Given two computers:

Has X gigabytes of RAM, that's the amount it ships with and that's all it will ever have, it can be designed around that number in whatever way is most efficient, solder chips directly to the motherboard if that turns out to save money, whatever.
Has X gigabytes of RAM, but field upgradable to 4X gigabytes.

How much does the expandability cost? That is, not the cost of buying the extra RAM at expansion time, but just to include the capability on the motherboard, how much does that add to the initial cost of the machine?

Does it have any effect on performance? If memory wasn't going to be expandable, could you shave cycles off memory access time or anything?


texts:
I have a Max 202 Ic and Max 232 Ic
I currently want to make a USB to RS232 Serial Db9 converter
i have the db9 male port, a max 232 and max 202 , usb female port and bunch of other passive components .
Is it possible to make a USB to DB9 Rs232 converter ? if yes , how ( any schematics ) ?
PS : also what is an alternative IC circuit to make USB to RS232 db9 ,  if this is not possible , ( i have this for my college project )
image : this is the project flow , as u can see at starting I need to make a USB to rs232 male DB 9 converter and this thread is about that