texts: How do I make a real-world verison of this LC circuit?

texts:
I'm trying to build the LC oscillator show on the bottom of this page for some school project and I'm having a bit of problems translating the theoretical circuit into a real-world one.

Here's the schematic:

I think I get how the circuit works on paper. We have a LC resonant circuit which will produce a certain output frequency. Because the energy in the circuit gets transferred out due to differences between theoretical components and real world components, the transistor is there to keep adding the energy into the circuit. The transistor is controlled by the coupled coil L2 in which we get current induced by the coil L which keeps switching the transistor

For the real world circuit I can use more or less whatever components I want, so my main limitation is that I only have a 1.2 mH 1:1 transformer available.

In some simulations I used that transformer and a \$ 470 \mu F\$ capacitor (I just happen to have one in my drawer) and the expected frequency should be around 212 Hz.

For some reason, the simulations don't seem to be working as expected and I can't figure out why.

For example here's a link to falstad circuit simulator and it's showing bad connections. I also only get the bottom half of the sinusoid.

In Multisim, I'm getting flat line on the oscilloscope with this circuit:

I don't know how to pick a right transistor for this circuit so I just took 2N2714 randomly.

Here's my question: How do I figure out why this doesn't simulate well and how do I determine what I need to look for when picking a transistor for the circuit?

UPDATE
Here's a new link for falstad simulator and it's an improvement. I'm still not getting expected oscillations from it though.


texts: In measuring relay contact resistance, should I use 4 wire measurement or calculate it using the voltage across the relay and current?

texts:
I'm reading mixed things online where a current from a typical ohmmeter is too low to accurately tell us the true resistance of the relay contacts.

I've got a 30V 2.5A power supply, electronic load, and an Agilent 3458A meter at my disposal.

The relays under test have a max carry current of 1.3A


texts: Relay/Contactor for 30A inrush, 250mA steady

texts:
I'm struggling to find any relay or contactor even close to the specs I need, and I've contacted many manufacturers. This is controlling a large contactor, so draws a 30A 24DC inrush current. It then settles to a 250mA hold current. It seems any relay large enough to handle the 30A inrush, then also has minimum current ratings well above 250mA. I can not seem to find anything to handle both, and I can't suppress the inrush.

Does anyone know of any such device? My only other potential idea is to use a number of small relays and split the current through possibly upwards of 12 contacts, so as to put a small current through each and be looking at more like a range of 20mA to 2.5A per contact. Even still, this is bad practice and will lead to failure anyway. Surely there must be a better way.


texts: Relationship between current and temperature

texts:
I am trying to find the specific current needed to heat up a wire to a specific temperature. The wire material is kanthal. I've calculated the resistance, from the resistivty and the dimensions of the wire. I also have the supply voltage.

But what is the relationship between Wattage and Temperature? How do I find out how much current needed to heat the wire to a specific temp?


texts:
I've recently been using an old cell phone charger as a single cell charger to manually charge 18650 li-ion cells. Below is some info about the charger & charging that I have measured.

Charger:
Voc = 5.25V  (Voltage open circuit (i.e. charger terminal V with no cell in  the charger)
Imax = .67A  (max current output of the charger -- no cell in the charger - tested with Ammeter on charger output terminal contacts)

Typical 3.7V Li-Ion Charging Conditions:
Voc  Vic  Aic
3V    5.25V    0A (bad cell - open cell)
3V    0V      .67A (bad cell - shorted cell)
3V    3.09V   .53A (530 mA) (typical good cell - low state of charge)
4.19V  4.2V   .05A (50mA) (typical good cell - near full charge - charging manually stopped)

Voc = Voltage open circuit (i.e. the voltage reading across the terminals of a 18650 Li-ion cell -- not in the charging circuit.)
Vic = Voltage in circuit (i.e. the voltmeter reading at the charger contacts when the cell is in the charger & normal charging is on.
Aic = Amperage in circuit (i.e. the Ammeter is in circuit to measure the current.)

I have installed a spdt switch & a resistor to manually limit charging current to .1A for cells that have an initial low Voc (i.e. < 3V) to reduce the charge rate until they are at 3V.  Then I flip the switch & charge them at the normal charge rate of .53A.

What this charger lacks is some way to set a CV of 4.1V to 4.2V and automatically shut off charging when the charge current = 50mA.  What is the easiest way for me to modify my charging circuit to allow for an adjustable high V limit of between 4.1V & 4.2V & use some kind of current sense resistor to trigger an audible alarm?


texts: How to determine IBM USB 6 pin header pinout?

texts:
I have two IBM Power 7 machines - Power720 and Power740 (8202-E4B and 8205-E6B) and both have an internal USB 6 pin header (labelled J3_TAPEUSB_SIGNAL). These are for connection to a single device (either an LTO drive, an RDX drive, etc.).

The IBM cable is either unobtainable or the price is insane, so I decided to just make one myself.

I am going to mount an RDX drive (dock). I already got the parts (the RDX, a USB Type B cable and a Dupont style 2x3 connector). Now the problem is, how do I determine the header pinout (using a multimeter, etc.) without frying the motherboard, port or any device attached to it?

I searched all over the place for IBM-related pinout information to no avail. So this is basically a hands-on job, hopefully without toasting anything.

Any help or pointers appreciated.

EDIT:

These are resistance and voltage readings I took as per @KH's recommendations:

As for other components/devices nearby, this is it (bottom right SAS backplane cable removed for clarity):

I tested impedance on the front and back USB Type A ports (receptacles) and got 1.2 Ohms on pin 4 (which can maybe match pin 3 top right on the header). All others infinity.

All readings done against the chassis.


texts: Cheap simple way to make an adjustable 1-10 MHz square or sine wave oscillator

texts: For a test of a filter and video transmitter gear, I need a variable frequency (potentiometer adjusted) sine or square wave oscillator, adjustable from about 1 to 10 MHz. Output about 1Vp-p okay, but I could reduce a higher output. I don't have many parts at the moment; so I need the cheapest way to do this. I have a lot of NOR gates lying around and I'm thinking of a ring oscillator but when I try to make them adjustable they become unstable.


texts: Can we program our smartphone camera to detect the frequency and time period of IR light?

texts: My use case is this: I am emitting morse code using a sole IR light source, and I intend to detect the frequency and the time period of the light source using my smartphone camera. Can this be done?


texts: Can I use LM3481 for a system where no-load status can occur?

texts:
I have made a step motor driver board with LM3478 to supply 24v from 12v input.

LM3478
The problem is that a user can power the board without the stepper connected board which drive the board to no-load status on LM3478. Just 2 stepper motor drivers(drv8825) are connected to 24V.
LM3481
After LM3478 circuit is broken and burnt, I googled the problem and found LM3478 is not a proper choice for this situation.
It seems like LM3481 might works with the following feature as stated in the datasheet, but I am not sure at all if this is the right one for my situation.
From the first page of the datasheet: "Pulse Skipping at Light Loads"
Will LM3481 work for my situation? If not, what are the other popular chips usable for my system?
Input: 9v~18v
Output: 24v, 1~2A


texts:
Can I design a counter to increment on the clock rising edge?
For example, I am tying to create a counter that increments on the rising edge of the clock if an input is a logic level 1. If the input is a 0 on the clock rising edge, the counter is not incremented. When I write this logic, the code doesn't synthesise.
It seems like a counter enable signal I need after the clock edge detection but it won't synthesise.
EDIT
The error I am getting is:
[Synth 8-27] else clause after check for clock not supported
[Synth 8-285] failed synthesizing module 'Encoder_Counter'
Code:
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;
use work.Data_Sizes_Package.ALL;

entity Encoder_Counter is
  Port (Clock : in std_logic;
        Count_Input_A, Count_Input_B : in std_logic;
        Reset_Counter : in std_logic;
        Counter_Value : out std_logic_vector(Data_width-1 downto 0)
       );
end Encoder_Counter;

 architecture Behavioral of Encoder_Counter is

signal Counter_Value_Temp : std_logic_vector(Data_width-1 downto 0) := (others => '0');

begin

Counter_Value <= Counter_Value_Temp;

    Process (Count_Input_A, Count_Input_B, Reset_Counter)

    begin

      if(rising_edge(Reset_Counter)) then   --rising or falling edge?????
      Counter_Value_Temp <= (others => '0');

      elsif(falling_edge(Clock)) then

        if(Count_Input_A = '1' or Count_Input_B = '1') then
        Counter_Value_Temp <= Counter_Value_Temp + 1;

        end if;

      end if;

    end Process;

end Behavioral;


texts: I'm designing a flex PCB to place on the back of a human hand and I need to print it out once in a while to compare the shape. In the output job file I have included the PCB printouts under Documentation but I can't seem to find any layer corresponding to the board margin.


texts: Function of transformer as a filter in isolated DC-DC converters

texts:
As far as I understand the isolation is achieved by a transformer(and besides this sometimes also using an optoisolator for the feedback part) in a DC-DC converter. And this is a galvanic isolation.(I don't know what really "truly isolated" means btw.)

But the transformers have leakage capacitances which means a trandformer will block unwanted DC but it will partially attenuate the AC interference. I guess the higher the ferq. the higher it will pass the unwanted interference.

I have two things where I'm totally blank about this topic. Here is an example of an isolated buck converter. Take for example the model TEN 5-2411.

What type of isolation will such a buck converter achieve? Will it help to attenuate common mode interference or differential mode interference between input and the output? And how can one infer from the datasheet the frequency range and for such isolation.

For example lets say we have this buck converter where we want to step down 24V to 5V DC. And imagine at the input these is 1MegHz 1Vpkpk common-mode noise or differential mode noise. How can we estimate the amount of the noise would appear at the 5V DC output?

Will the transformer block CM noise but not DM noise? If so, how can it help preventing ground loops? A ground loop is not CM.


texts: PCB prototyping with Presensitized copper boards

texts:
I'm currently working on my first PCB prototyping by using some pre-sensitized PCB board, purchased from Maplins UK. However, I'm having terrible trouble exposing and developing the board, it just never seems to turn out right. I haven't even reached the etching stage yet because I'm not happy with the presensitized developing results. I'm looking for general tips and tricks, and how to follow the right 'path' to success — I seem to be getting worse at it for some reason! ;-)

I am using inkjet transparency sheets with the darkest tone applied for the mask, and after noticing you can see light thru the printed areas on the mask, I decided to double up, and sellotaped two identical transparencies aligned on top of each other. You can hold it up to the light and still see a kind of dull purple glow, but it is mostly opaque. I acknowledge this may be one of the causes of my troubles!

I started off using a normal 100 watt lightbulb, with little success; exposures seemed to take 40 minutes and beyond to have any effect at all, and got very warm. I used to hold the mask down onto the board using glass, but after realising glass blocks a lot of UV light, I decided to switch to a sheet of clear acrylic.

I then found a cheap portable UV sterilizer, which actually claims to emit UV-C light; I know UV-A is the type required to expose the board as far as I can work out but it seems to be having a much quicker effect, I see an effect even after just two minutes exposure. The manual states it uses a "Long life 4 watt germicidal UV lamp", and yes, it's not what you'd call bright. The longest exposure I have done so far is about six minutes, and I still saw the same problem (see below).

According to their site, the boards are supposedly developed using a caustic soda solution.

On all of my attempts, I am seeing the circuit pattern appear, but the developed copper which is to be etched away ends up nowhere near as shiny as I'd expect it to be — I am expecting the photoresist layer to completely dissipate resulting in exposed shiny copper, going by a lot of those reference PCB etching sites on the internet. Instead I end up with varying degrees of random areas of shiny copper but mostly dull copper (partially disolved photoresist), and other areas complete bluey greeny photoresist layer. I haven't tried etching yet, but its not difficult to see why I expect such a poorly exposed and developed board to poorly etch too. I can't imagine the 'mostly dull copper' areas will etch at all given the photoresist is only partially dissipated.

I'm cutting off small areas of my two medium sized pre-sensitized boards for testing purposes, and I'm running out quickly!

So I am unclear and am proceeding very slowly because of all these variables:

Not sure about exposure time (for my lamp).
Not sure about UV light position and height required.
Not sure if my mask pattern is opaque enough (to UV light).
Not sure about correct proportions of caustic soda to water.
Not sure about time to leave the board in the caustic soda — whether I'm going too far developing.
Not sure about dipping in water to stop the development — Can you put it back in the caustic soda to continue development if you didn't leave it in long enough? Also how can you tell!?
I also don't know whether a developed pre-sensitized board stays so, and won't fade as its left in daylight over time. How long before normal daylight affects a pre-sensitized developed board?

Any help anybody could give me would be appreciated. I haven't kept a decent log of my activities, to learn effectively, because I thought I'd have nailed it by now! However I can provide pictures of my efforts so far, if need be.


texts: What to place first: termination or pullup/pulldown?

texts:
simulate this circuit – Schematic created using CircuitLab

I am routing some ethernet signals that have termination resistors as well as pulldown resistors, my question is that as the signal comes out of the chip, what should I place first - the termination resistor followed by pulldown, or have them both connect directly to the output?

Datasheet makes no mention of this sequence of resistors
http://www.ti.com/product/DP83848I/technicaldocuments


texts: Specific Questions Regarding Use of Regulated Switching Supplies

texts:
For a project I am working on, I have 3 regulated switching supplies, 5v 5a, 12v 5a, 24v 2a. They are the standard, passively-cooled type which look like this

My question:
Can I stack these/have them making contact with each other? I have a very small space to work within, and don't want to screw anything up!


texts: MSP430 Coding, Can I Place an Interrupt Vector Inside a Function?

texts:
As the title said, I am trying to see if an Interrupt Vector can be embedded inside a function? I am using IAR, but gcc or ccs would work too. I don't see it done in any code online. Example:

void function_funtime (int test){
    int lm4970_state = 0;
    int abc = test + 3;

    // Port 1 interrupt service routine
    #pragma vector = PORT1_VECTOR
    __interrupt void Port_1_ISR (void)
    {
         _BIC_SR_IRQ(LPM3_bits + GIE);     // Clear LPM/Disable Interrupts
         lm4970_state++;     // Increase LM4970 state by 1
         P1IFG &= ~PB;       // P1.3 IFG cleared
    }
}

Function "function_funtime" is called from the main code before the interrupt is ever seen. Can this be done?


texts: Li-Ion Battery Charging Board Temprature (Junction Temp)

texts:
I'm looking for a little help with a simple battery charging project. I've bought a pack of cheap USB charging boards on ebay (link) with the intent of using one to charge a small Li-Ion battery. While testing it, I've noticed that the board is running pretty hot. Within 30 seconds of plugging it into a USB wall adapter (5V,1A output), the charging board heats up to ~140F/60C (according to my multimeter's thermometer probe). The battery, however, stays room temp.

I was pretty concerned about this, but after looking up the spec sheet for the charging IC (TC4056A), I see it lists the maximum junction temperature as 125C (257F). As I understand it, the max "junction temperature" is the component's max operating temperature.

This project is a bit of a learning experience for me, so I'm wondering if this sounds ok. While 140F is well below the chip's junction temp, it just seems really high. Thank you for your help.


texts: Am I misunderstanding steady state power disspation calculations?

texts:
I am looking at the Littlefuse 5KP series. It says on the datasheet:

I am trying to understand how they arrive at \$P_D\$ = 8.0W.

Given thermal resistances of 40°C/W or 8.0°C/W, and 100°C temperature difference, should \$P_D\$ not be either 2.5W or 12.5W?

Oddly enough for the Littlefuse SMBJ series, they use the thermal resistance junction to lead to calculate \$P_D\$. (The equivalent of 12.5W above.)

Where does the discrepancy come from? Is it due to the difference of leaded vs SMD components? Inconsistency in the datasheet? Or am I misunderstanding something?

Also: What is the point of specifying \$P_D\$ "on an infinite heat sink" for a round component with leads? Where is the heat sink supposed to go? Why is this seemingly purely theoretical value useful at all?


texts: Analog circuit to generate a pair of non-intersecting PWM signals

texts:
I want to generate two PWM signals, each used to drive LEDs. The sum of both duty cycles will never exceed 100%, so I want the signals to be non-overlapping in order to limit peak currents.
The two channels are controlled by respective voltages IN1 and IN2, whose limits are set by reference voltages REF_TOP and REF_BOT such that VCC > REF_TOP > REF_BOT > VSS.
I want it so that when IN1 ≥ REF_TOP, PWM1 is at 100% duty cycle; when IN1 ≤ REF_BOT, PWM1 is at 0% duty cycle, and varies linearly in between. The same is true respctively for IN2 and PWM2.
So far, I have come up with this atrocity:

My idea goes like this:

when the output of U3 is at minimum (close to VSS), the output of U5 gradually rises. When it reaches REF_TOP,  U1, acting as a comparator, brings its output close to VCC, which in turn, through D1, gets U3 to bring its output at maximum.
when the output of U3 is at maximum, the output of U5 gradually goes down. When it reaches REF_BOT, U2 brings its output close to VCC, which in turn, through D2, gets U3 to bring its output at minimum.
thus, at the output of U5, we get a triangular signal going up and down between REF_TOP and REF_BOT
furthermore, U4 and U6 act in the same way as U3 and U5, but with reversed inputs - thus, at the output of U6, we also get a triangular wave locked between REF_TOP and REF_BOT, but with its phase exactly complementary to the other one
now, comparators U7 and U8 give us PWM signals with complementary phase and the correct duty cycles, which are fed into MOSFET drivers U9 and U10.

Although this works in simulation, it has some drawbacks:

the shape second triangle wave depends on C1 and C2 being completely identical - in practice, U6 will rise/fall a bit slower/faster than U5, which will make its triangle wave cut off / malformed, which will incur some inaccuracy in the PWM2 duty cycle
it has many components (that's a lot of opamps!)

So, my questions are these:

my Y problem: What is a less stupid way to generate complementary triangle waves locked between two reference voltages?
my X problem: Is there a better way to approach this entire problem?

Note:
I am doing this with analog circuitry and not with a microcontroller because I need a relatively high frequency (about 20kHz) and granularity (about 14 bits). This would require a timer clocked at 300+ MHz.


texts: A beginner that could use a few tips on wiring my first circuit involving relays

texts:
I am in no way experienced or knowledgeable with circuits or electronics passed installing my own car subwoofers and amps, or swapping out pickups on a guitar which means I only basically know how to solder.

I want to make sure that I wasn't going to blow myself up, or the chip that I've been checking the mail every day for 30 days to get to me from China.

I have a circuit that does not require any power. I just need it to open and close. Not introducing any power into that circuit that's all I want to happen. I can do this by just having a gap in the circuit and touching each side of a wire to bridge the gap.

Now I want to make it so that same simple bridge happens from a button I press.

After researching I think I have the right parts, I got an RF receiver and transmitter that are both 315 MHz. (receiver is pictured) it is powered by 3 V-12 V (I will use 9 V).
I just wanted to make sure that this circuit wasn't trying to send the 9 V through the circuit. I want it to just open and close an external circuit.

This one says it has 0 V output which seems to be what I'm looking for.

Anyone have tips on how to wire this thing up to do what I need or am I not even using the right parts?


texts: Can we install product above FCC test power level declared in certification report

texts:
we have a product which has radio of 1W maximum output power , we have sent product for FCC through party lab, and they certified the product with 18 dbm only.
So we get the certificate with only 18 dbm.

But in field we need to use more power like 25 dbm. So can we use this power even if we certified the module at 18 dbm or we need to repeat the whole FCC test again.


texts: Issue with circuit board implementing temperature circuit

texts:
I have not got a lot of experience with PCBs, but I have moved a breadboard circuit to a PCB and I am seeing an issue.
The objective of the board is to sense temperature. When the circuit is on the breadboard it works as intended, but when I get the corresponding PCB from the manufacturer, the temperature values are wrong.
I am looking for feedback or suggestions that might help pinpoint this issue. Below are the schematic and the PCB layout from Eagle.


texts:
I have been looking into using LDPC's in some of my projects and have had some questions come up. Currently my structure looks something like this:

I am then able to have hardware wake when it sees the preamble, read the length byte, and even check CRC for me before my processor has to handle the packet at all. This takes a lot of load off of processing time as well as code writing time.

What I am wondering is if there is any hardware out there that can use LDPC or any other correction code in a similar manner to what I am currently doing. Preferably it would be included with the wireless module, especially if it is able to do some soft decoding, but I am starting to think there isn't anything out there that does that currently. Because of this I am also open to "in-line" hardware that can assist with this.

So, know of anything?


texts: What is the difference between full duplex and dual simplex? I can not really distinguish the difference. Is it the fact that in full duplex, data can be exchanged simultaneously in both channels while in dual simplex, it's only one at the time? Is PCI Express well a dual simplex?


texts: Using straight connectors with screw endpoint?

texts:
I am a complete newbie to wiring but have almost completed the install of a MOSFET board on my 3D Printer. Felt it was necessary to avoid potential fires that this particular printer is known for.

I'm on the last step and need to install the positive/negative wires for the hotbed on the MOSFET board. The connectors already on them are straight (can be seen on the black one) but need to go under the metal plate on the board.

Will this be fine or should I cut them and put spade connectors instead? Doing that would void my warranty and the wires are already really short as is, why I would prefer to keep the current connectors if they won't be a problem.


texts: Altium Designer - Method for changing the size of multiple pads at the same time

texts:
I want to edit multiple pads at the same time to have the same dimensions. I have tried selecting multiple pads and editing one of them, but that only changes the selected pad.

Is there a method for editing multiple pads at the same time?


texts: Buck Converter MOSFET Output Voltage distorted (PWM)

texts:
The input to my buck converter MOSFET switch is a PWM signal with a certain duty cycle. However, upon observing the voltage waveform of the MOSFET, the voltage is a bit distorted.

The input to MOSFET (PWM signal) and output of MOSFET is observed and pictures are attached.

The first picture is PWM Input to MOSFET (Blue Waveform) and the 2nd picture is MOSFET Output Voltage (Blue Waveform)

Thanks


texts:
I've to do some work on TINIS400 & TINIM400 evaluation kit From Dallas Semiconductor. These boards are now obsolete and the TINI SDK is therfore no longer available on the Dallas Semiconductor website.

Any idea where I might be able to download the TINI SDK?

Thanks..


texts: Will this circuit work using BC 108 transistor

texts:
Hi guys i have circuit diagram from everyday practical electronics magzine
and i want to make it but there are two problem about the circuits one is
the transistor BC 108 used in this circuit and the second thing is i am
wondering will that work having it made so i want to know is there any
equivalent of BC 108 and and will this circuit work ?


texts: What is the I/O standard for the PCIe data lines?

texts:
I am entering the pin information of my FPGA design using the Altera Quartus II PinPlanner. One of the components of my design is PCIe, and I am having troubles understanding the "I/O standard" associated with the PCIe data pins (one rx and tx for each PCIe lane).

This website claims that the PCIe lines are LVDS. However, looking at the example given for my FPGA devkit (which contains PCIe) I see that they are using either 1.5-V PCML or 2.5V I/O standards, not LVDS.

What is the I/O standard associated to the PCIe data line? Could the Altera Cyclone IV require a PCIe I/O standard that is somehow different from the PCIe electrical specifications?


texts: What is the effect of Saturation on a Ferrite Bead Inductor?

texts:
This circuit shows the "current channel" of an energy meter.

IA_IN are the two inputs for a shunt (typically 250 uOhms) while TP1 is the connection to the energy measurement IC, which uses the 3.3 V supply voltage (V3P3) as a reference.

The input uses ferrite beads as a form of filter for the incoming AC signal. I want to know what the effect of saturation will be on the ferrite bead inductors at the input.


texts: Voltage and current measurement of battery Single ended or differential?

texts:
I am trying to measure battery's current and voltage for a battery charging/monitoring project. I have read all about current sensing (including high side & low side sensing). And i have decided to use Shunt resistors for current measurement as they are accurate as compared to other current measuring devices. My battery would be a Li-Ion Battery, and the maximum rating of this battery stand would be (4.3V , 40A).

However i am confused on how to measure the voltage and current using an ADC, i-e whether it should be measured single endedly or differentially. A very rough sketch of my circuit is given below.
(This ADC would be interfaced with a microcontroller)

The battery can be seen connected to a buck converter for the charging purpose. And and ADC can be seen as well.

(Please note that my sketches might not be accurate, but i mean all what i have written here and in the diagrams)

What i think is that, if i try to measure my Battery's voltage and current in this way (shown in the image below), my voltage would be differential(since battery's negative terminal is not directly grounded, theres a shunt in between) so i have to feed it to a differential input ADC, whereas the current is to be measured singe endedly, as one leg of the shunt is grounded.

And if i try to measure my Battery's voltage and current in this way (shown in the image below), my voltage would be singe ended (since the battery's negative terminal is directly grounded), and my current measurement would have to be done differentially (as my shunt is placed in between my supply and the battery).

Now, i am no expert in ADCs, but as far as i have read about them (also their data sheets), if an ADC has both single and differential ended inputs, we can use it as a single ended input ADC OR we can use it as a differential ended input ADC. Which means we cannot use it as both single and differential input at the same time.

Which brings me to my question. What could be a solution to it ? Shall i use 2 different ADCs, one for single ended input and the other for differential ended input ? Or can i measure both the current and voltage differentially and feeding them both to a single ADC configured as a differential ended input ADC ? P.S i am not looking forward to use a single to differential ended AMP , as i am supposed to measure these quantities with as high accuracy as possible, and introducing such AMP would decrease my system's measurement accuracy.

So it leaves the question, whether i can measure both the quantities differentially ? like given in the picture below, which is just feeding the voltage measurement connections to the '+'and '-' input of a differential ended input ADC. As the Battery's negative terminal in this case would be at ground potential, so can it be fed to '-' terminal of a differential input ADC ? (Since i dont have much knowledge in field of electronics, i dont know if it would be possible or not, or what i am asking here is totally stupid)

You helful comments would be really appreciated,

Thankyou.

Thankyou.


texts:
I want to build a T-flip flop in Verilog. So far I have written the following code, but I wish they could see if it is correct please. The machine I was using to make the code is in the image.

module flopJK(q,j,k,c);
 input j,k,c;
 output q;
 reg q;
 always @(posedge c)
 begin
  case ({j,k})
   {1'b0,1'b0}:begin q=q; end
   {1'b0,1'b1}:begin q=1'b0; end
   {1'b1, 1'b0}:begin q=1'b1; end
   {1'b1, 1'b1}:begin q=~q; end
  endcase
 end
endmodule


texts: Join together two flexible electrical cables

texts:
I have 2 electrical cables (audio cables) of same diameter that I want to join, with a connection as discreet as possible. It is common to use some dominos for this kind of task, but these are really to visible. In a perfect world, I'd like the connection to be nearly invisible, as if the cable was not cut.

Do you know how I may do this ?
Precision : I do not want to weld, I don't know how to do it and I don't have the needed material.


texts: How can I easily convert an analog signal to a digital signal?

texts:
I've tried searching for an answer on this topic but I must be phrasing it wrong because I can't find anything.

I have a voltage range of about a 1 volt. I want to pass it through an Op Amp (or something else) to convert it to a 0 V - 3.3 V signal to trip a digital interrupt pin. My friend told me about Rail to Rail op amps but I have a 741 I can use that I have in my kit right now.

Is there an easy way to use a 741 op amp to do this conversion? My VCC is 3V3 & my GND is 0 V and I would really like to avoid using a negative voltage in this circuit.

I know it must be possible because I have a light sensor breakout board that takes a 0 V - 3.3 V supply and outputs a digital 1 or 0.
http://www.dx.com/p/photoactivity-diode-light-sensor-detection-sensor-module-152611#.Vbet_6GlvVM

Is there a better way to do this? It must feed an interrupt pin so please don't suggest sending it to an ADC.

Thanks in advance!


texts: Buck converter input voltage lower than the designed output voltage

texts:
I have this buck converter which is designed to produce an output voltage of 9V for an input range of 18V-36V.
The datasheet of the buck converter mentions that the minimum required input voltage is 4.5V.
Assume my buck converter circuit & feedback network resistors and inductors are designed for 9V.
I am curious to know what will happen at the output of the buck converter when I give an input voltage between 5V and 8V.
I understand that the buck converter will step down the voltage if the input voltage is higher than the output voltage.
But what would happen if the input voltage is lower than the required output voltage for which the output circuit section of the buck converter is designed?
Can someone let me know on what would happen and why would that happen in this scenario?


texts:
The figure is about how DDR SDRAM and DDR SDRAM2 works.

After taking some time searching, I still cannot understand the figure. Can anyone please help me understand it? In this case, is the "operating frequency of internal bus" the frequency of the whole computer system? What is the "External clock frequency"? I am so lost.


texts: How do I identify SMD components? (or how do I identify any component)

texts:
How do I identify the markings on an SMT component and match it up with a part number so I can be a good designer and actually look at a datasheet (and read the whole thing)?
Or identify a part to replace an unknown part on a PCB?


texts:
All remote microphones sends digital samples over the ether. Why no analog remote microphones?

I know that digital signals are less sensitive to noises, but there are several advantages of analog counterpart.

Simpler (only an AM/FM modulator/demodulator required)
Cheaper (no high performance AD/DA required) (Most mixers are analogue so DA is required too)
Lower latency (this is not significant)

Do I miss something?


texts: I have a small toy electromagnetic levitation device that I need to power externally instead of being plugged into a wall. The device uses an AC/DC adapter with a barrel jack connection that outputs 5V at 1A. What can I replace this with to power it without an outlet? I have an Anker USB battery pack. Will that work somehow with a certain cable? I don't know much about this topic. Any help is appreciated. Thanks.


texts: At what cable lengths are termination resistors required for RS-485 networks?

texts: I've noticed my experiments in the lab with RS-485 work fine with fairly short cables, but termination resistors are needed for true installations.  Is their presence or absence a function of the cable length, or other factors?


texts: Overcurrent and overload, current and load

texts:
I know that current is measured in Amperes, and is tied to voltage and resistance in a circuit by Ohm's Law. Load, on the other hand, seems to be a concept tied to the number of appliances connected in a circuit. But what is the exact relationship between current and load, or overcurrent and overload?

So, since I'm interested in the wiring inside a home, and voltage inside homes here is fixed (in my case 220-240 V AC), current equals load. The case would be different if I was considering a circuit where the voltage within the circuit would change with time. Please correct me if I'm wrong.

Thanks.


texts: Can the serial input of a parallel input/serial output shift register be used as an additional input?

texts:
Can the serial input of a parallel input/serial output shift register, such as the 74LS165N, be used as an additional input as it were a 9 input shift register?

If it works, I think the input would be read at a slightly later time, but for reading switches, would that matter?


texts:
I've got a Flights of Fancy AM crystal receiver that has been in the attic for years. I want to put it together but can't find the instruction booklet. Is anyone familiar with this receiver? Does anyone know how it should be wired?

I just add a schematic of how it was wired about 10 years ago. There is no capacitor anywhere. The last wrap of the coil wire is about 3" long and just hangs in the air.

Using a 15ft long antenna and sweeping across the 5" length of coil I get only two stations. Any ideas what would improve it?

I would appreciate any thoughts on my latest schematic below. I've also added a resistor.

Thanks,
henrylr


texts: Recovering from run time errors on stm32l0

texts:
I have the independent watch dog running and I get rare resets for unknown reasons.

How can I catch these errors and do a controlled reset. I want to store some things in EEPROM and then restart the application.

Unplugging the device however, the device needs to forget everything it knows. So I only want to restore EEPROM if an error occured.

void HardFault_Handler(void){
      EEPROM_save_ram();
}

void Reset_Handler(void){
     EEPROM_restore_ram();
}

Is there a bit that shows me if its a warm restart? A watchdog reset? or just a normal cold start?


texts:
When adding extra electrons to pure silicon in a conduction band, the extra electrons will occupy a donor level below the conduction band (we get n-type), as shown here:
When adding electron-deficient dopant atom to pure silicon in a valence band, this provides an acceptor level above the valence band (we get p-type), as shown here:
Is this definition of doping semiconductors true? Is this donor energy part of conduction band or it is between conduction and valence band (so in forbidden gap)? And same for acceptor energy?


texts: Drive 12V Automotive Relay from 3.3v ESP32

texts:
I am working on a project to start a vehicle using Automotive Relays.   And I am following this circuit in the tutorial to do so. Everything works fine on Arduino UNO. But I want to use ESP32 of this kind in my final project and ESP32 is 3.3v with ~12mA max current. When I plug ESP32 to the above-given circuit (Obviously powering through external 5v connection with the shared ground and not 12v battery), it fails to trigger the relay and instead resets. Any suggestions?

My ESP32 Circuit.


texts: Why is it when I set up a Johnson counter, the number sequence rotates fine, but I can't get a ring counter right (explanation below)?

texts:
With a Johnson counter, I hook up every flip flop's Q output to the following flip flop's D input, for D flip flops.  And then the final Q' output is hooked into the first flip flop's D input.  When I simulate this in Multisim, it runs through the numbers fine:

1000
1100
1110
1111
0111
0011
0001
0000
and rotate...

Setting up a Ring counter doesn't seem to work though.  From what I understand, it's the same thing, except the last Q' output is left alone, and instead the last Q output is hooked to the first D input.  When I do this, though, none of the LED lights turn on.

A ring counter is supposed to do this:

1000
0100
0010
0001
and rotate...

I am baffled, so any help or pointers would be great.  I google'd this and couldn't find anything.

UPDATE:

Okay, I added an interactive digital constant that goes to the set for the first flip flop.  When I run it, I set it to 1, then immediately set it to 0, and then it rotates through the numbers just fine for a Ring counter.  However, I'd like it to do that automatically without having to do that.  How can I have the first flip flop initially set to 1 without having to do all that?


texts: Hot air soldering without destroying ICs

texts:
I have designed a circuit board that has about 20 parts on it, including a surface mount LMV431 Adjustable Zener Shunt Regulator and MMBT2907 PNP transistor.

It appears that every time I solder up a board, the Zener and/or PNP transistor get cooked and do not function properly afterwards.  Specifically, the Zener never goes to a high-Z state as it is supposed to (keeps conducting regardless of conditions) and the PNP transistor doesn't shut off (keeps allowing current flow even with zero base current).

Here is my soldering process:

Heat up bottom of PCB with hot air rework station set to 150C on maximum air setting for about 2 minutes holding hot air tip at 30° relative to PCB.  In last 20 seconds ramp temp up to 280°C
Reduce air flow to ~4/8 setting, keeping temp set at 280°C, and immediately begin heating up entire top surface of the PCB, moving the tip constantly at a speed of ~ 8cm/s and tip distance of approx. 1.25”.  Do this for 20-30 seconds
Reduce tip distance from board to ~0.5” and begin focusing heat in 2 cm diameter swirls on the section of the board nearest the USB connector landing area.  Focus heat on capacitors and resistors in this area, and leads of FET.  Make sure to revert back to the 8cm/s area heating from the last step on the part of the board that is not being reflowed in order to make sure its temp stays up.  Probably reverting back to this every 10 seconds for 1 or 2 seconds is advisable.
Blow on 45° angle all around the FET to get the solder underneath to reflow
Move reflow target area to the Zener/PNP side of PCB, taking care to keep tip moving fairly fast.  Try to avoid aiming tip directly at Zener or PNP, instead trying to blow just to the side of them to get their leads to reflow

According to the Zener datasheet, the maximum temperature during soldering is 260 C:

At this point I'm worried because I can't seem to assemble a working prototype in order to validate the design (need to be 100% sure that the inconsistent go/nogo between the 5 boards that I've assembled is indeed due to thermal stress during reflow and not an inherent flaw in the circuit).

Should I give up trying to do this with a hot air rework station and buy a reflow oven?


texts: For a lower voltage drop one could use Schottky diodes, but what are the disadvantages of Schottky's?

texts: In other words, why don't we always use Schottky diodes if they are so much better? What diode properties do Schottky diodes have that makes them unfit for certain applications?


texts:
I want to know does the SIM800L module connect to the network automatically without any user commands?

Because some modules will disconnect in low signal areas & some SIMs will be disconnected by service providers until we pay the monthly bills.

I do not set or poll any network related commands on power up, I just set some SMS commands & Echo off only.The modules works nicely on workbench but not sure above will happen in one day...!!


texts:
In this circuit:

Assuming ideal diodes

We have 8 combinations of assumptions. I have proved that 5 of them are wrong. The three remaining assumptions are:

All diodes are on.
D1 is on, D2 is off, and D3 is on.
D1 is on, D2 is on, and D3 is off.

When all diodes are on, the circuit will look like this:

I = (16 - 12) / 4.7k = 0.85 mA.

Vo = 16v.

When D1 is on, D2 is on, and D3 is off, the circuit will look like this:

I = (16 - 12) / 4.7k = 0.85 mA.

Vo = 16v

3 is identical to 2.

So, is it possible that we have three valid assumptions in this circuit? and if not, what is the wrong with this solution?


texts: Does multiplying range affect accuracy of an analog to digital converter?

texts:
Suppose the built in analog to digital converter of a microcontroller has an operating voltage of 0-5 V. These values are converted to integers ranging from 0-1023. So the resolution is 5/1024.
I want to measure an analog value ranging from 0-1 V.
If I multiply the analog value by 5 in a microcontroller that reads the value (using the multiplication operator in software,) will the resolution be 1/1024?


texts:
I am trying to reconstruct and measure AC current with a current transformer (ratio 1:2500) and an MCU (ATmega328p) like shown in this schematic, so the input voltage will be between 5V and 0V with zero point at 2.5V.

It works OK (with a little offset), but I want to know how can be properly prevented an overvoltage on the MCU input (like if the voltage will be more than 5V or less than 0V) that can damage the MCU?

simulate this circuit – Schematic created using CircuitLab


texts:
In the past I have seen two different symbols for a zener diode. One shows the complete "Z" shape on the cathode, and one shows more of an "L" shape on the cathode (see images below):

What is the difference between these? Do they actually have different meanings, or are they two ways of showing the same thing? Perhaps one is European and one is American? I always thought that they were simply two ways of showing the same thing, but a coworker of mine questioned it and now I am looking for confirmation.


texts: how to store array of long integer values to 16 bit memory

texts:
I am trying to store "long int" values to memory (SM28VLT32) via SPI communication. I am using IAR compiler. Memory is 16 bit read or write access. I would like to store bigger than 16 bit value like "3245672341" and some times float values. ex: "5008.456". I can convert float to int then the integer will be bigger than 16 bit value. I have to store an array of [6] "long int"values every minit to memory.
I can not store long integer value to memory as it has 16 bit read and write access.

I am thinking to convert "long int" to "string"! Any suggestions on how can i store those values and should use less memory?

Presently i am able to store 16 bit integer value using the below coode.

unsigned int sampledata[5]= {34586, 43877,53780, 64879,1};
FlashPointer = 2;

int StoreToFlash(unsigned int sampledata[], int StartAddress);  // Strore Sample to flash

StoreToFlash(sampledata, FlashPointer);   //function calling

int StoreToFlash(long int sampledata[], int StartAddress)
{
int iCtr;
int ErrorCode = 0;
int address = StartAddress;

// Write to flash
for(iCtr=0;iCtr<5;iCtr++)
{
    ErrorCode = Flash_Write(address++, sampledata[iCtr]);
    if((ErrorCode &0x45)!= 0)
    {
      Flash_ClearError();
    }
}
return ErrorCode;
}

int Flash_Write(int Address, long int Data)   //Flash wirte function
{
int error ;
int data0 = 0;

// Make chip select Low
Flash_Set_CS_Status(0);

// Send Command ID 0x17
data0 = Flash_SPI_SendByte(0x17);

// Send Address Byte 3
data0 = Flash_SPI_SendByte((Address & 0xFF0000) >> 16);

// Send Address Byte 2
data0 = Flash_SPI_SendByte((Address & 0xFF00) >> 8);

// Send Address Byte 1
data0 = Flash_SPI_SendByte(Address & 0xFF);

// Send Data Byte MSB
data0 = Flash_SPI_SendByte((Data & 0xFF00) >> 8);

// Send Data Byte LSB
data0 = Flash_SPI_SendByte(Data & 0xFF);

// Send Dummy Byte
data0 = Flash_SPI_SendByte(0);

// Make Chip select high
Flash_Set_CS_Status(1);
}

How can i store sampledata[5]= {3456782676, 3890.345, 5035.675, 1, 64534}?


texts:
simulate this circuit – Schematic created using CircuitLab

This schematic is a bit difficult for me to understand due to the short (red). What is I3, the current over R3 (indicated with open terminals, in blue)?


texts:
How would I implement an differencing op amp circuit that performs the operation 5*v1-2*v2 with the op amp power supply being 12vdc? I already tried the basic circuit but I got negative resistance. Is that normal?

Schematic:


texts: Understanding LiPo charging / protection circuit

texts:
I'm in the process of learning to design PCBs and understanding electronics design. For a project, I need to charge a 3.7V LiPo battery. I also want to protect it from over‑charging / over‑discharging.

I've been experimenting with boards that use the TP4056 together with a DW01 battery protection IC and FS8205A dual N-channel MOSFET.

The datasheets are available here:

TP4056
DW01
FS8205A

The pre-built modules are very cheap - here is an example on AliExpress:

They seem to work, but I would like to know what the circuit is actually doing before I use it :)

I've only found one schematic with these three components combined:

I'm having a hard time to figure out if this circuit is correct. If I understand correctly, the dual N-channel MOSFET is basically 2 switches in one package. Those two MOSFETs are triggered by pins 1 and 3 of the DW01, which are described as:

DW01 pin 1: MOSFET gate connection pin for discharge control
DW01 pin 3: MOSFET gate connection pin for charge control

So basically the two MOSFETs in the FS8205A are switching off the flow to B-, when DW01 tells them to do so.

I understand that this would work when the over-discharge control kicks in, no power would be flowing from B- to OUT-

However what I don't understand, is how this would work with the over-charge protection? When that kicks in, no power should be flowing from the charger to the battery, however, the device that is connected to OUT+ and OUT- should still be able to work, but it seems like B- would not reach OUT-


texts: Intentional RF emitter failing unintentional emission test?

texts: Suppose a commercial product uses a FCC pre-certified WiFi module. If the quality is not consistent throughout the batch, I'd guess some pre-certified modules may produce unacceptable emissions. In that case, could these emissions fail the unintentional emission test for the final product? Or is it that pre-certified modules are somehow isolated during the test such that the emissions produced by the pre-certified modules will not affect the unintentional emission test outcomes?


texts: Doubt regarding ADD instruction of the 8086 microprocessor

texts: I have a doubt regarding the usage of the ADD instruction in Intel 8086 microprocessor.Don't ADD AX,BX and ADD AX,[BX] mean the same thing?


texts: How do I choose a transistor to operate in active/linear mode?

texts:
Short version:
I want to operate a transistor (of any type, but presumably MOSFET/BJT) in its "partial" on state to regulate current through various LEDs, but I'm not sure what transistor type to use, nor how to pick one of said type.
I've got two white LEDs in series, plus an RGB LED, so 4 channels total.

The specs/requirements are:

Supply voltage of 12 V for white LEDs, 3.3-5 V (trimmable) for RGB
Max current of 4.8 A for white, 1 A per color for RGB; typical perhaps 1.5 A white / 0.3 A RGB
Currents smoothly adjustable down to exactly zero, without a step anywhere (e.g. 0 A when off, 0.2 - 5 A when on)
LED forward voltages of 11.2~11.8 V (typical) and 2.2~3.9 for the various colors, over the entire current ranges
Control from 3.3 volt MCU/DAC; <10 mA current capability
Low-side transistor placement
DC operation, current will be unchanging for hours at a time
Relatively low cost (a couple of USD per transistor or less)
DPAK/D2PAK or similar hand-solderable packages with some power dissipation capability (the PCB is 0.8 mm/2 oz, with filled thermal vias, and heatsinked)

Long version:

I've designed a linear LED driver, with at least a decent understanding of its pros and cons (mainly the con of power dissipation). The main advantages I'm after is entirely flicker-free operation and relative ease of design. I'm doing this for four channels, so going with something more complex such as a constant current buck converter isn't really feasible; that's also likely above my skill level.

I used a low-side MOSFET to regulate the current; the MOSFET gate is driven by a DAC, and said DAC is controlled by a microcontroller using a PID loop. There's a current shunt on the high side so that the MCU can regulate the MOSFET to get the desired current.

Since I want to control this from a 3.3 V MCU, I picked out a MOSFET with a low threshold voltage and low RDS(on) (in case I run out of supply voltage at high currents, and want the entire supply voltage across the load).

This all seemed fine to me, until yesterday, when I learned about thermal instability in power MOSFETs. Apparently, my choice of a low RDS(on) MOSFET is a very bad choice when operating in linear mode, as modern "trench" MOSFETs are designed for fast switching only, minimizing time spent not fully on or off, and can fail catastrophically during extended linear-mode operation -- especially at lower gate voltages (such as in my case of <3.3 V at all times).

I'm not sure how much this applies to me, since VDS < 12 V and IDS < 5 A at all times, and they will never be very high simultaneously. I expect less than 3.5 W of power dissipation worst-case.

After a bit of looking at MOSFETs optimized for linear operation, I could only find ones designed for extreme levels of operation, such as 500-1000 volts at power dissipations of hundreds of watts... and prices of $50 and upwards per MOSFET.

Next, I read up a bit on BJTs, but found other drawbacks, most notably the high Vce(sat) voltages that could cause a lot of waste heat during "fully on" operation. I'd also need either a Darlington transistor or some other combination (perhaps a MOSFET driving the BJT base?) to be able to regulate 0-5 A with a <10 mA output DAC.

How should I approach this? Should I go with a plain MOSFET, since the drain-source current and voltages will never be high simultaneously, or something else?

Edit for comments:

LED datasheets:
White LEDs, Cree XHP70.2, 2x in the 6 V-configuration in series
RGB LEDs, Cree XM-L Color

I will add a schematic soon; adding the entire project's schematic is overkill for the question, so I'll need to draw one up.

As mentioned, the MCU runs a PID controller to adjust the DAC output; the prototype (on a single 3 mm LED) works fine at ~300 Hz, and settles in perhaps 50-100 ms, which is more than good enough.


texts:
Question boils down to whether the voltage across a capacitor can ever exceed Q/C.  It relates to what happens to the drain-source capacitance when a NFET turns off.  At the start of turn off V_ds and charge of C_ds is essentially zero.  In my case drain current is a low 1.5mA.  When gate voltage is removed and drops to V_gp (at the Miller plateau) I_d remains constant at 1.5mA and V_ds starts to rise and reaches it maximum (V_dd) when the gate-drain capacitance is discharged in a few nsec (at the end of the Miller plateau.)  Then I_d starts to fall to zero.  My problem is, unless V of a capacitor can ever exceed Q/C, which I think it cannot, V_ds cannot rise any faster than the drain-source capacitance can be charged.  If the drain-source capacitance takes all of the drain current, I_d, (does it or is the current divided between the capacitance and the drain-source FET path??) I calculate it would take about 350nsec for V_ds to reach 90%.  Calculation is not straight forward:  in my case I have a 5.6K resistor feeding C_ds, but that changes from 50pf at V_ds = 0 to 26pf at V_ds = 10.  The datasheet says turn off is 8nsec.  I calculate 350nsec.  Am I doing this correctly?

There are encyclopedias on the gate-drain and the gate-source parasitic capacitances, but nothing that I could find on the drain-source capacitance.  I suspect because all example use 1A to 20A as the drain current which will charge the D-S capacitance in a flash.


texts: How to drive 2/3 color LED's and circuit schematic

texts:
I need to use 2 or 3 color LED for my circuit.(preferably 3 color one).  I am going to use PIC18F26K83 to control the LED. However, I am confused how am I going to make it change colour. I think I need to give different voltage values to it. (For 3 colour one it says: 1.9V Green, 1.85V Red, 1.9V Yellow) In this case what will it be if I give it 1.9V?. To sum up my questions are:

What do I need to do in order to use make the LED to change colour? Do I need to change voltage value of it? If yes how can I change it? Via hardware?
I have a circuit for 2 colour LED and it works fine. Can I also use exact same circuit if I need to replace 2 colour LED to 3 colour one? Do I need to replace any components? (See the datasheets below)

Datasheet of the 2 LED's and circuit schematic are below:

2 colour LED datasheet

3 colour LED datasheet


texts: How do determine MOSFET parameters in LTSPICE

texts:
I am designing a phase locked loop on LTspice (which I'm new to), but have come across a snag in the procedure:

Is there a way to determine the output resistance of a mosfet (as the I'm not able to determine the early voltage or lambda from the model file)?
How does one separate the gain and the phase plot on performing AC analysis?
Finally, how to determine the varying \$g_m\$ (transconductance) that is induced by the body effect whilst performing DC analysis?.


texts: Why are identical value vs different value capacitors between positive and negative voltage supply leads?

texts: I understand why various different value capacitor are added in low voltage power supplies....to be able to respond and absorb various size/frequency spikes.  But why are there also identical value capacitors in a row?


texts: My ATTiny84 circuit works fine until I connect a piezo buzzer

texts:
I've got a mini-game coded with an ATTiny84, a shifter, 7 LEDs and two buttons, plus accompanying resistors. It works great! Until I connect a passive piezo buzzer, that is. Then the timings go off, code gets "stuck", it's really strange.

The amazing thing is I don't even need to USE the buzzer -- just having it in the circuit kills the system. The moment I unplug it from ground everything works.

I'm powering the whole thing up with 3 AAAs as per recommendations elsewhere. No voltage regulators or capacitors... could that be the problem? Or is it an ATTiny84 thing? Anyone know what's going on?

(I had the buzzer working fine before when I was using an ATMega128 and the Arduino UNO's power source.)

Am I missing something like this? Using a microcomputer in the drive circuit of a piezo buzzer

Thanks in advance!


texts:
I'm porting some software from Microchip PIC (using the HI-Tech C Compiler) to TI MSP430, and in the existing code they access the pins directly with something like:
RA1 = 1;

Is there a similar way to do this with the MSP430, or do I have to write to the entire input/output register each time? If it is not possible has any one come up with a good equivalent? I am using Code Composer Studio v5.3 and the compiler that comes with that.


texts: Do I need to isolate the output voltage feedback in SMPS?

texts:
I almost finish with my Half-Bridge SMPS design. I'm now designing the output voltage feedback to the controller stage.

The controller stage drives both MOSFET transistor through an isolation transformer and the power supply for the controller stage is a separate 12V-50Hz transformer so there is a complete isolation between the controller stage and 220V power line.

Now my question is: Do I need to isolate the output voltage feedback using opto-isolators? I know I have to isolate from the 220V power line because of it's high voltage but do I need to do it for my output voltage? The output is 35V 10A max.

The book Power Supply Cookbook from Marty Brown explains I need isolation from the output stage to the control stage but doesn't explain why.

Here is a simple block diagram where you can see the control stage is completely isolated. In my case I can't power the control circuit from the same secondary because voltage goes from 1V to 35V.


texts: Dometic cfx50w fridge - how to choose small DIY battery setup

texts:
I am looking for some help to understand what kind of battery could power a Dometic cfx50w 12/24/120V compressor fridge, while on-the-go. Here are the electrical specifications:

  Input voltage (AC) 120-240 V
  Input voltage (DC) 12/24 V
  Rated input current (AC) 0.79 A
  Rated input current (DC) 7.8 A
  Input frequency 50/60 Hz

(Link to full fridge specifications)

Most people choose a dual battery DC/DC setup for their car. I am looking for a more compact and portable solution, to get a few hours (minimum 4) running in normal conditions. I am thinking of a battery pack like those used in the RC hobby. Would this work?

I am looking for best battery chemistry and recommended ah rating considering the fridge would run for 10 minutes every hour and battery would have to provide 4 hours of power without getting damaged. Fridge has a cutoff voltage of 11.1v. I am wondering if lipo or lifepo4 batteries could replace a flooded lead acid and what would be the usable capacity. Battery would be charged at home by small rc charger.


texts: Pulse reset line with long press of a button

texts:
This question is a variation of How to trigger reset at long press of button.

Namely, I need to pull down a reset line with a short pulse of X length, if a button is pressed for Y>=X or more seconds. To be clear, I need for the reset line to go low for X seconds and then go up again without having to depress the button (this is different to the cited question, since I can't rely on the button being depressed for the signal to go up again).

To give some example values here, suppose I want to bring the reset line to low for 5uS if a button is pressed for 5 seconds or more. It is acceptable if the this 5uS pulse gets generated every 5 seconds for as long as the button remains pressed (i.e. a pulse train), but generating a single pulse is all I really need.

One way to achieve this would be using a pulse generator IC, or other specialized IC's. However, ideally I would like to do it using only simpler components (Rs, Cs and perhaps a transistor or mosfet if required).


texts:
how the battery behaves in this diagram

how a battery behaves in parallel to the charger with a shared load but with a voltage difference


texts: What methods are there for storing electrical potential energy in water vapor?

texts: for an engineering class I had to create an electrical energy storage device and I began thinking about  thunderstorms (I think it was a cloudy day) and how they create lighting. I know it's not feasible, but would it be possible to store a charge in water vapor (maybe like a capacitor). Could that water vapor then be stored in a container and be discharged whenever you connect the container (I am thinking like a metal lead coming out of a soda bottle) to a ground? The thought of a thunderstorm in a bottle seems like a very dangerous but cool idea (not that I would use it for my project, I was just wondering if this would be possible).


texts:
I have a problem which is somehow related to detecting a peak. Let me summarize the problem a little bit, so it might be clear to you. I have to signals, both are not periodic and I know when they start and when they end. I also know the signal has exactely one peak. The signal might be a bit noisy, but I think this could be eliminated.
Now I need to know when between the start and end point the peak occurs. The best option would be that I get an output signal as soon as the peak occurs. Yet, I do not know how high the peak will be. This can vary a lot. The signal itself looks like a gaussian.

Now I could use a high speed ADC and sample the signal continously, do some small calculations and get the peak. Yet, what I would like much more, would be if I simply get an "event" telling me: There was the peak. I don't mind if I get this signal a bit later, as long as the time difference between the peak and the event is constant. I absolutely do NOT care about the peak level, I only want to know the point in time when this happened.

Does anyone know of a circuit which is able to satisfy these requirements?


texts: Why not specify the z axies in module pcb?

texts:
I have a 3 axis Accerelometer (MPU6050) PCB,

but the indication in PCB tells it has only X AND Y axis rotation, why??


texts: How to quantify the effect of the common mode input for a given CMRR?

texts:
The definition of CMRR is 20×log10(Aol/Acm) where Aol is the open loop gain and Acm is the common mode gain.

If we have a buffer with 20dB CMRR opamp and if we apply 1V differential input along with 1V common mode input as shown in my hand drawn example:

In this case we dont know the open loop gain but we know the CMRR. What will be the total output voltage? In other words how to quantify the contribution of the 1V common mode input to the output voltage. We are using feedback here so would that effect CMRR?

Edit:

Look at a data acquisition input parameters:

CMRR is given as 92dB but Aol never mentioned. Does that mean we cannot quantify Acm?


texts: Circuit on a breadboard is not working properly

texts:
I have built the following circuit but it doesn't seem to work properly! The sound from the speaker should be maintained until the power is cut off but it is only maintained as long as the reed switch is ON. I have tried to built it again and again based on different equivalent  circuits but it doesn't work! What is the problem?

The original schematics is the following:

simulate this circuit – Schematic created using CircuitLab

The equivalent schematic and the circuit I built on the breadboard are the following:

simulate this circuit


texts: UL 1971: is there a tolerance on strobe flash rates?

texts:
UL 1971 27.1.3(a) requires that listed strobes used for fire alarm signaling to hearing-impaired occupants flash at between 1 and 2 flashes per second:

a) Signaling lights shall produce a candela output in effective intensity in accordance with Tables 27.1 – 27.3 and Figures 27.1 – 27.3. The flash rate shall not be less than 1 hertz or greater than 2 hertz over the rated operating voltage range.

However, in practice, UL 1971 listed strobes, such as the System Sensor L-Series, are produced with a specified flash rate of 1 flash per second.  This raises a question: is there a measurement tolerance on the 27.1.3(a) flash rate requirement, or does the listing process for these strobes require the flash rate to be strictly between 1 and 2 Hz over the operating temperature range, time (when the strobe is free running), and any unit-to-unit variation that may be present?


texts: Do N-channel MOSFETs require a pull-down resistor?

texts:
I'm using an N-channel mosfet to supply power to a servo. The problem is that even with the gate set at low, I'm still getting some amount of voltage (~0.9V in a 5V system) coming through. Do I need a pull-down in case the pin is floating?

Here's the current schematic:


texts: NPN Transistor Pre-Amp Circuit - How do I calculate gain and voltage output?

texts:
I am calculating the voltage output of the below circuit. The output I have calculated varies by 0.1 of a volt compared with the simulation I created using multisim, but I am not certain this is correct.

The questions I have:

Are the below calculations correct?
How do I display the results in decibels
What is the ouput voltage with no load?

Thank You.

Values:

$$Vs=70mV_{peak}$$
$$2n9304\beta = 100$$

DC Analysis:

$$V_B=Vcc.(R2/(R2+R1))=1.689V $$
$$V_E=V_B-0.7V=0.989V$$
$$I_E=(V_E/(R4+R5))=0.899mA$$
$$V_C=VCC.(IC*R3)=3.022V$$
$$RE=(V_T/I_E)=(23mV/0.899mA)=25.584\Omega$$

AC Analysis (Voltage Gain):

$$Av_{no load}=V_{out}/V_{in}=((R3*IC)/((RE+R4)*IE)=(2.2k\Omega/125.584)=17.518 $$

$$Z_{in}=(R1||R2)||(Z_{INQ})$$

$$Z_{INQ}=V_{in}/I_{in}=(125.584*I_E)/I_B=12683.984\Omega$$

$$Z_{in}=2667.24$$

$$OutputVoltage=V_s*(Z_{in}/(Z_{in}*Rs)*Av_{no load}*(RL/(RL+R3)$$

$$OutputVoltage=0.929_p=1.857_{p-p}$$


texts: Jerk in Power plants due to breakdown of transmission line

texts: I read in news paper "heavy jerk in power plant due to breakdown in transmission line" what does it mean why does it happen?


texts: Output resistance of a BJT in saturation

texts:
It seems by the characteristic curve of a BJT, that it behaves as a resistance in saturation region.

Is this conclusion true? and if so how can I calculate this resistance (seen from collector) from datasheet values?


texts: Connecting negative terminal of DC power supply to negative terminal of other DC supply

texts:
I'm wiring up an electrical box that has several sensors, relays and a PLC. The PLC and relays are powered with a 24Vdc power supply. The sensors, which provide an analog input to the PLC, are powered by a separate 24Vdc power supply.

In wiring all this up, I've inadvertently connected the negative terminals of the two DC power supplied together. The positive terminals are still separate. I've traced all the wires back and cannot find a source of the connection.

Is it bad to leave the negative terminals connected? Should I find the connection and remove it?

Thanks


texts: Burning hex files into multiple micro-controllers at a time.

texts:
I am using attiny88 and the usbasp programmer. Right now I am burning 1 micro at a time. But it is a time-consuming process during the production.
Is there any way to burn multiple microcontrollers at a time just using 1 programmer? If I want to roll out my own software to do such a thing, what should be the procedure to do so and what are the thing will I need?
Thankyou


texts: Help needed configuring battery bank out of smaller cells

texts:
Due to availability and not practicality, I am attempting to build an as large as possible battery bank from 16 AH AGM batteries.

The end goal is a large system that is charged with a solar system that is scalable for future upgrades, while also able to be grid charged. The inititial solar kit I'm planning to use is a 540 watt system including a 40 amp charge controller. The manufacturer informed me I would not be able to link more than 3 batteries in parallel on this 12v system, but general research hasn't been able to provide me with any reasoning for this other than uneven charging.

On a side note, I am considering using a bus bar system with jumper wires for each battery. If I opt to use this system it is my understanding that I create the option of easily monitoring individual battery voltages, as well as fuse each battery.

Highly motivated to move forward with this project but I would like to do so with a solid plan in place.

Thank you for reading, looking forward to input!


texts:
I have two circuits, a latching circuit and a simple 12 VDC to 5 VDC circuit using a 7805.  I would like to combine these two circuits if possible.  The voltage source would be a 12 VDC battery.  When the button is pressed, it should then turn on the 7805 and the latching circuit.  Could someone show me how it is done?  Here are the two circuits I have. I imagine it would probably go somewhere along the green line I made?  Without adding it into the latching circuit, would I just be burning off heat (draining my battery) because it would be constantly trying to supply 5 V?

simulate this circuit – Schematic created using CircuitLab


texts: How does a clock cycle delay skip a computer instruction?

texts:
This is from the Wikipedia entry on Pirate decryption

  The signals moving between the smartcard and the receiver can be
  easily intercepted and analyzed. They can be vulnerable to a "glitch"
  by which the incoming power and clock signals are disrupted for a
  short and carefully timed length of time (such as a millionth of a
  second) in order to cause the processor to skip an instruction. In
  many cases, off-the-shelf hardware with modified firmware designed to
  exploit this weakness was sold to pirates for use in tampering with
  cards for the US-based DirecTV system.


texts: Is the formual for winding distribution factor and winding pitch factor for n-phase (intergal-slot winding) machine as 3-phase machine?

texts:
[]

1 In Image, alpha is the slot angle and eta'v' is harmonic-ordinal, q= solts per pole per phase
[2]All book provide formula for 3-phase winding, and so far no material for n-phase winding.
  Kindly provide me the formula or suggest me literature


texts: What do the markings 40/100/56/B mean on this capacitor?

texts:
I am trying to replace a steam iron capacitor which has the following markings

I know that it's 0.68 micro Farad with 10% tolerance, but I can't seem to understand the 40/100/56 marking. There's replacements online with 40/100/21 so I'd like to know if they're suitable.
Thank you.


texts: Metal enclosure for custom car stereo project

texts:
I'm thinking about developing a custom car stereo, and it surprised me that there's no DIY enclosures for this purpose. I've just found plastic boxes in the 1 DIN size which can be installed into an empty radio apartment of the car to hold stuff, but they are not an option for electronic development. I'm looking for something which is made of metal and allows me to mount a PCB inside and to fix the connectors on the back of the box. (optionally with ready installed ISO connectors, antenna socket and a front plastic panel to cut out mount holes for control/display would be nice aswell).

Is there really nothing for this, or I'm just searching with the wrong keywords?

(Maybe it's not the best place to ask. If it's so then please redirect me to the correct Stackexchange subsite and will move this question there.)


texts:
Can you help me identify the correct values of the marked capacitors? And what are the values between the brackets?

As a bonus question: What is the purpose of this transistors?
The schematics show a one line UART with 13V, 500 boud. The upper part is the receiving part, the lower for sending.

Thank you.


texts: Transient analysis of a step down converter with control loop

texts:
I am trying to run a transient simulation of a step down dc-dc converter using ideal components. This includes a feedback loop consisting of an error amplifier. I am interested in transient response without including any compensation.

I have used a voltage controlled voltage source without any saturation limits for an error amplifier. If I use an ideal opamp, it would saturate even though there is a feedback loop. Why?

If I use an ideal comparator to compare the control voltage with a sawtooth signal of desired frequency fs (same as switching frequency), I would get a PWM output whose frequency will not be fs. Below is the schematic and corresponding transient simulation (Multisim):

Since there is not saturation limit set for voltage-controlled-voltage source, I can have arbitrarily large gain to reduce the error. But the ideal comparator will compare the control voltage with sawtooth signal even if the control voltage is very high initially(that is why I've not included it in plot above). But the output is a PWM signal with a different frequency.

So I tried using a PWM control block instead of a comparator.

But the problem is that unlike an ideal comprator this block will not output a PWM signal with such high values of control voltage. In order to achieve this I have to set the amplitude of sawtooth reference used by PWM block to very high values so that Vcontrol and sawtooth signal intersect each other.

But the result is a pefrect PWM signal with frequency same as fs.

I wanted to analyze the effects of changing amplitude of sawtooth signal, gain of VCVS on transient response. But for obtaining a proper output I have to simulate using impractical values. Is there any other way to obtain a proper PWM signal using an ideal comparator?

EDIT:

Input voltage = 12V

Required Output = 6V

Steady state duty cycle is 50%

Switching frequency fs = 1Mhz


texts: Newbie: resistor and capacitor symbols meaning

texts:
I found a project I'm interested in on the Internet ( http://linnix.com/udip/ ). However, I'm a total beginner to electronics, and I'm not sure about the values of the elements as described in the schematics (see below):

Does a "R220" resistor here mean 22 ohms, or 0.22 ohms? [edit: solved, 22 ohm +/- 5%, see below]
Does a "C180" capacitor mean 18pF? In some articles I read that a capacitor symbol contains a letter after the number, meaning tolerance of the capacitor. Here, I don't see such a letter — is it important? Or does the "C" letter mean it here (+/- 0.25pF)? [edit: solved, 18pF, "+/-10% should be fine", see below]
Similarly, "C105" = 1µF? (and what about the tolerance?) [edit: solved, 1µF +/- 10%, see below]
I believe I can assume the board is powered by the UVCC line (from USB), so VCC doesn't need power, only the capacitor to GND? [edit: partially solved, "yes"; but what about GND vs. UVSS?]

I'd be very grateful for help!

Edit: Wrote some answers above, based on answer by @markrages, and on some more info from atmega32u2's reference (20.3.3 Design guidelines).

Edit 2: Moved questions 5, 7 into: "how to ground?" and "which variant of bus-powered?". Also, deleted question 6, I hope I'll be able to solve it myself later.


texts: What's the issue in this LEDS blinking PIC18 ASM code?

texts:
I got to code the typical example of 8 LEDS turning ON and OFF, then all getting ON in a loop.

I got a PIC 18F4550, and coded this:

    List    P=18F4550               ;Microcontrolador a utilizar
    include <P18F4550.inc>          ;Definiciones de constantes

;**********   Palabra de conficuración  *******************************************
    CONFIG FOSC = INTOSC_EC ;INTOSC_EC          ; Internal oscillator
    CONFIG PWRT= ON             ; Power-up Timer Enable bit
    CONFIG BOR=OFF              ; Brown-out Reset disabled in hardware and software
    CONFIG WDT=OFF              ; WDT disabled
    CONFIG MCLRE=ON             ; MCLR pin enabled
    CONFIG PBADEN=OFF           ; PORTB<4:0> pins are configured as digital I/O
    CONFIG LVP=OFF              ; Single-Supply ICSP disabled
    CONFIG DEBUG = OFF                  ; Background debugger disabled
    CONFIG XINST = OFF          ; Extended Instruction disabled
;******************************Variables***********************************
    conta equ 0x00

;**********************************************************************************

    org     0x0000
    movlw   0x62
    movwf   OSCCON
    clrf    TRISD

CICLO
    bcf PORTD,0
    call RETARDO
    bsf PORTD,0
    bcf PORTD,1
    CALL RETARDO

        bcf PORTD,1
    call RETARDO
    bsf PORTD,1
    bcf PORTD,2
    CALL RETARDO

        bcf PORTD,2
    call RETARDO
    bsf PORTD,2
    bcf PORTD,3
    CALL RETARDO

        bcf PORTD,3
    call RETARDO
    bsf PORTD,3
    bcf PORTD,4
    CALL RETARDO

        bcf PORTD,4
    call RETARDO
    bsf PORTD,4
    bcf PORTD,5
    CALL RETARDO

        bcf PORTD,5
    call RETARDO
    bsf PORTD,5
    bcf PORTD,6
    CALL RETARDO

        bcf PORTD,6
    call RETARDO
    bsf PORTD,6
    bcf PORTD,7
    CALL RETARDO

        bcf PORTD,7
    call RETARDO
    bsf PORTD,7
        bcf PORTD,0
    CALL RETARDO

bra  CICLO

RETARDO
    movlw   .255
    movwf   conta

    CICLO2
         DECFSZ   conta,F

    bra  CICLO2

    nop
    nop
    nop
    nop

    return

    end

tWhen I simulate, That code is almost working. Sometimes they get turning ON and OFF one after another starting at first led, but sometimes the sequence leaps and some random LEDS get ON unexepectedly.

I tried to add this portion of code before bra CICLO to produce the whole leds ON effect, but it just made it behave the worst.

bcf PORTD,0
bcf PORTD,1
bcf PORTD,2
bcf PORTD,3
bcf PORTD,4
bcf PORTD,5
bcf PORTD,6
CALL RETARDO
bsf PORTD,1
bsf PORTD,2
bsf PORTD,3
bsf PORTD,4
bsf PORTD,5
bsf PORTD,6
bsf PORTD,7
CALL RETARDO

This is a picture of my simulation:

What am I doing wrong? How could I make sure, working at 4 MhZ that delays will be 1 second?


texts:
I came across this circuit in pioneer brand vsx522 model amplifier circuit diagram. This supposed to initialize the microcontroller during AC power up.

But it looks like wrongly drawn. The resistor on the left is directly connected to the 3.3V linear regulator which is powered by a tiny mains 240V 50 Hz standby transformer. The output of this circuit, at least in my perception, is used to initialize the micro controller and it looks like will locked up at high state (3.3V) indefinitely. The transistor and everything else around it cannot pull the RESET to low.

Am I right? Or do I miss anything? The values of components are not fully specified.


texts:
I would like to visualize the RF signal of a 6 Channel Spektrum DX6i transmitter that operates in the 2.4 GHz band, in order to visualize changes in the signal when I move the control sticks.

The Tx converts the position of the control sticks into a Pulse-Position modulation (PPM) signal which is then modulated using Direct-Sequence Spread Spectrum (DSSS) and then radiated at 2.4 GHz.

Unfortunately, according to my teacher, the equipment that we have in our University labs don't have the required performance to analyze 2.4 GHz signals, and all the inputs that I got from him were discouraging, because the oscilloscopes that can operate in such bands are very expensive.

This is an incomplete list with some equipment that is available in our labs:

Digital Oscilloscopes:

100MHz - 1Ga/s GwINSTEC GDS-2102
100MHz - 1Ga/s Agilent DSO3102A

Analog Oscilloscopes:

40MHz HAMEG HM-404 / HM-407

Spectrum Analyzers:

100kHz - 3GHz Agilent N1996A
9kHZ - 4GHz Anritsu MS2034A
9kHz - 2.6GHz ADVANTEST R3361A
10kHz - 3.5GHz ADVANTEST R4131B

Network Analyzers:

S-Parameter 30kHz - 6GHz Agilent 8753ES

The reason for posting this list is to give readers some reference. I am curious about Spectrum Analyzers and Network Analyzers because they can operate at 2.4 GHz so I have included them just in case they could be useful.

I'm not giving in yet and I am exploring other alternatives such as software-defined oscilloscopes.

But before going any further I would like to ask:

Is it possible to visualize a 2.4 GHz digital signal without an oscilloscope?

I read this question and found it useful.


texts: Smartphones - are they fully functionally tested?

texts: Smartphones are among the most complex devices ever produced. When they are being manufactured I assume each subsystem is independently tested for functionality. However, is the final finished product fully tested? By that, I mean is it switched on and connected to a network as part of a final testing procedure?


texts: Detecting button press over computer network

texts:
I would like to make a networked device (along the lines of hotel room service call) that has multiple input lines that may be uniquely identified on a computer on the network.

I found a product with similar functionality.

I assume the device will require a microcontroller interfaced with an Ethernet I/O controller? Do I need to have an OS to generate TCP/IP message packets that may be detected on a PC? Kindly suggest a block scheme I can follow to do this.


texts: What is slew rate control for an input GPIO?

texts: I see a register where you can make the slew rate fast or slow for the GPIO. Does this matter when GPIO is configured as an input?


texts: Which is give better result for find angular position of device using 9-axis IMU snesor.?

texts:
I'm Using LSM9DSO 9 axis Sensor Which gives output of Accelerometer , gyroscope , Magnetometer Output data. i want to find the angular position of the device using this sensor.

currently i'm trying to find an angle of device of x-axis but data is fluctuate so , i have refer some websites and documents which show that it is find using Accelerometer data also but i have little confuse about to which is better solution to find angular position of device.


texts: Can triac opto-coupler used as a simple optocoupler?

texts:
I had more than 50 pcs of MO3041 but in my circuit need operation like 817.
I know i can use 817 for DC circuit but i am just  want to know if i can use MO3041 in DC circuit.

I know there is a simple solution to just use a 817 Optocoupler, but i am just curious that does it possible?


texts:
A buddy of mine and I have a project in which we have to implement a PCI Express rootport. I haven't read the entire specification, nor do I have the Mindshare book that everyone recommends, but I think I have a reasonable grasp on the subject.

We're using an Arria 10 FPGA and we're running Quartus 18.1 on a Linux PC.

We'd like to start of quite simple. Something like this example design: https://fpgawiki.intel.com/uploads/e/e9/Basic_rootport_demo.pdf

This is my understanding of how it works. Correct me if I'm wrong:

The configuration space resides inside the PCIe IP. Memory space and optionally IO space reside inside the computer, which is connected via JTAG. First the rootport maps the bus structure. It does this by first sending a cfg0 write, which sets the primary bus number (root port IP), secondary bus number (any device connected to the IP) and subordinate bus number (highest bus number that's directly or indirectly connected to the IP). These number are used for TLPs that are routed by ID (like any cfg TLP).

It then sends a cfg1 write to the device ID that's given by the secondary bus number. The device number and function number can be assumed to be zero.

This brings me to my first question: How does one know if a device has multiple functions?

This cfg1 write tlp writes the PCIe base address of BAR0 into the configuration space of the endpoint. Any address routed TLP that has the same base address, but might have a different offset gets routed to BAR0.

Wouldn't the rootport first write all 1's to this entry of the configuration space and read it back to determine the size it needs to allocate for this BAR?

The rootport then writes to the command register in the configuration space of the endpoint, to configure the endpoint to enable the capabilities we want. In this case it enables the memory space enable bit and the bus master bit.

Setting the base address of the BAR and the command register could have been done in a single transaction right?

The rootport then writes the base address of its BAR0 into its own configuration space, after which it also writes to the command register of its own configuration space also enabling the memory space and the bus master bit.

Again, this could have been done in one transaction, right?

After this, the rootport configures the endpoint's BARs. Again, it would normally do this by writing all 1s and read back the value to determine the size it needs to allocate for each address range, right?

All in all it seems like a great example design. However, since its been created in an older version of Quartus, I can't build it. I was wondering if you knew what Avalon-ST IPs I could use that are in the current version of Quartus to rebuild this design?

How exactly is rx_st_bar used? It seems the PCIe IP analyzes the TLPs and sets a bit based on where it needs to go. For an endpoint it seems pretty straightforward since the TLPs can only be addressed to either one of the BARs, an expansion ROM or the rest of a device's memory space.

For a rootport it seems a little more complicated however, since there are also bits for the primary, secondary and subordinate bus number window as well as an IO, non-prefetchable and prefetchable window. It is my understanding that these last 3 windows are used to map all PCIe addresses inside the rootport. I wonder how exactly this is done, since it seems received TLPs are involved. Those bus number windows are also vague to me. Or are these used for PCIe switches to determine if a TLP is meant for the rootport or a device on another PCIe link?

I think these are all the questions I have for now. Your help is greatly appreciated.


texts: Constant Current LED Driver with Raspberry Pi Zero W

texts:
I have a 12 V DC source that I'm wanting to run a Raspberry Pi Zero and a couple of 3 W IR LEDs.  I'm not using the Pi to control the LEDs in any way.  The LEDs are just to provide lighting at night for a camera running on the Pi.

I have a cc/cv buck converter to run constant current to the LEDs at 1600 mA.  If I limit the output voltage to 5 V, could I run the Raspberry Pi off the same buck converter?  Or do I need to do this in 2 parts with one converter to reduce 12 V to 5 V for the Pi, then run another separate converter to keep the constant current for the LEDs?


texts: At what level of complexity should I consider UL listing my widget?

texts:
I am interested in making a widget to sell, but it will probably have a small market and small volume.  At what level of complexity should I consider UL listing (or otherwise certifying) my widget?

I presume that device complexity is the range I should measure the device against to obtain a safety certification.  I understand it costs several thousand dollars for such things.  For a widget with only a few dollars in parts (off the shelf/eBay prices), and a small market or run, it doesn't make much business sense for sure.

However, in general, what level of complexity should I consider to procure some kind of safety certification?

The particular widget I am thinking of right now is a PCB with connectors and possibly a small 24V to 12V transformer (<100ma).  Basically, something that was wirenutted/butt-spliced together will now be more professional looking on a board in a box.

Don't let the example distract you from the overall question though.


texts:
I've looked at the other answers here regarding building a low voltage UPS and have come up with the following design.

Requirements: 1) At least a couple of hours of up time; 2) USB power 5V @500mA, DECT phone 9V @300mA, DSL Modem + Router both 12V @250mA; 3) Always connected/auto switch over.

Components BoM: 1) 12V Lead Acid battery  + commercial intelligent charger; 2) Use 3 SEPIC converters to supply the 3 different voltages.

Simply connect together and leave permanently plugged in. I need a charger with enough power to keep the battery charged, as well as the devices operational. When the mains power fails, the SEPIC converters go from dropping the 13.8-14.5V charging voltage (typically what I have seen from car chargers) to their set voltage and then maintaining that voltage as the power drains from the battery.

Having tested a decent sized car battery, I know that will power the DSL modem + router for nearly 2 days (just connected straight to the battery, no converter). Maybe overkill but I do have at least one going spare. Those devices didn't like being connected to battery + charger though. Hopefully the SEPIC controllers will provide a steady voltage.

My questions are:

1) What size battery and charger should I go for? Assuming the SEPIC converters are 90% efficient I would need less than 1.5A to power them all full time. One of my car batteries specifies a bench charge rate of 4A, I assume that once fully charged the trickle requirement would be a lot less - it seems to measure less, about 150mA DC.

2) Do I need to add a mains detecting changeover relay to switch from the charger supplying power to the devices to the battery?

Thanks for getting this far.


texts:
I've bought a bunch a LED strips

A friend has built a system using http://resolume.com/ with http://www.heroicrobotics.com/products/pixelpusher controllers, however from what I've read this is geared toward iOS.

An easy-to-use iOS application is available from LED Labs - specifically designed for PixelPusher, and supporting it seamlessly.

I am a Windows programmer by trade and want to program these LED strips using C# ideally.
I just want to know how I can output to the LED strips via a Windows PC? I'm fine with the software side I just need some guidance with outputting to the hardware.
Programmatically using a 1 dimensional array of RGB co-ords I can sequence, eg a few functions with for loops to create shows.
Help much appreciated!


texts: REYAX RYP820U mPCIE (actually USB2) GPS/GLONASS/BeiDou module and PPS

texts:
So, I thought I might try to set a time server (as one does). I have a nano ITX mb with a mPCIe slot on it, and I found a GPS card that supposedly outputs a 'timepulse'. It was cheap enough that I thought I could give it a try. After a bit of fiddling with gpsd I get a 3D fix, but no PPS data. So, shouldn't this give me a time pulse..? I sent an email to the manufacturer; I get a schematic back, apparently the timepulse is hooked up to pin 42 in the mPCIe connector. Now I don't know what to do. Is there any way to get the PPS signal from pin 42 in the mPCIe connector and into ntpd? Doesn't seem like any PPS kernel modules supports this natively, and PPS-tools is no help either.

Any assistance appreciated.


texts: Can a micro operation pass multiple pipeline stages with a single clock cycle?

texts:
I'm learning a CPU architecture and currently found some high-level description of Intel x86_64 CPUs architecture. By the high level description I mean something like the following micro-op flow (might be wrong, this is how I currently see it):

1. Fetching code from memory
2. Caching the code in L1I cache
3. Activating Legacy Decode Pipeline
4. Put the decoded micro ops into the Decoded ICache and to the micro-ops queue (a.k.a IDQ)
5. Send micro-ops from the micro-op queue to RAT (a.k.a Renamer)
6. Allocate necessary resources and send micro-ops to the Reservation Station (a.k.a. Scheduler)
7. Dispatch micro-ops to the appropriate port
8. Write the result of the micro-ops to the writeback bus
9. Retire the micro-op

The question is if it is possible for micro-op to pass multiple pipeline stages for a single clock cycle?

For example:

A bunch of micro-ops are fetched from the Decoded ICache and put to the IDQ then the Renamer moves the micro-ops to the RS during the same clock cycle
Renamer moving a micro-op from IDQ to RS and then RS dispatches the micro-op to an issue port during the same clock cycle
When OOO core finishes execution of a micro-op its result is written to the writeback bus and then the micro-op is retired during the same clock-cycle.

Is it technically possible?


texts:
I have a Matlab simulation which implements vector control with an LC filter

The simulation comprises a voltage source inverter feeding an LC filter model whose output is passed to an induction motor dynamic model

I am trying to implement active damping as detailed here
http://vbn.aau.dk/ws/files/73019790/EPSH1_730_appendix_report.pdf

http://vbn.aau.dk/ws/files/71774890/EPSH1_730_paper.pdf
Which shows the transfer function block

My problem is the report is very vague, it doesnt explain a lot and I am struggling to understand what I am supposed to do

The authors don't go into much detail such as transforms, given there is a PI controller then that tells me that Vref should be a Dc quantity hence I need to transform into the e-frame which is fine

My problems are multiple there is a top heavy transfer function which simulink cant handle and it looks like the Vout is calculated where as in the report they mention measuring the output voltage again I believe this needs to be transformed to the eframe

My simulink model measures output voltage and load currents and the angle is calculated with an encoder and slip equation

I am at a loss as to how I implement this system

Do I measure the filter output voltages and transform to e frame and subtract from the Vref? which is the output voltage from the VC?

How do I get simulink to work with a transfer function that has an higher order numerator than denominator?

Any help/guidance would be most appreciated


texts: Why higher temperatures shorten the lifespan of a PC component?

texts:
It is usually advised to keep the temperatures low for every component of a PC. Not only there is a fan (or similar system) for the CPU or GPU, but there are optional fans for RAM, or hard disks.

While I understand the need of a CPU/GPU fan, since those units can probably melt or burn if not kept at normal temperatures, I'm unsure about the reason to, for example:

decrease the temperature of a hard disk from 104°F (40°C) to 86°F (30°C),
decrease the temperature of RAM from 113°F (45°C) to 95°F (35°C).

I've read in several places that lower temperatures increase the lifespan of hardware. But what are the reasons behind? How a 15-20°F decrease influences the hardware when we talk about the temperatures which are not as high as would be the temperature of a quad-core CPU used at 95% with no fan? What parts of the hardware are affected? Well, in short, what's happening?


texts: Difference between On-die and junction temperature

texts:
What is the difference between junction and on-die temperature.
I am using Xilinx Artix-7 FPGA


texts: How to connect a switch to a microcontroller in an extremly noisy environment

texts:
I'm currently working on redesigning the control circuit of a CNC machine (more specific: an Isel milling cutter). Only the digital part will be of interest, I'll keep the old power electronics (motor drivers and power supplies). Currently all parts of the circuitry are working well independent of each other, but when it comes to putting it all together, my circuit fails at several spots.
Measurements told me that this is mainly due to enormous EMI, crosstalk and other forms of electric noise, radiated from the power supply and some high-frequency, high-current traces going to the stepper motors.

In the second version of the PCB I want to solve all these (and some other) problems by making the circuit design as resistant to interference as possible.
What worries me the most are some DC signal lines that share the same physical cable with the motor's power lines (4x 48V 3A 300kHz stepping speed - the actual current frequency will be by far lower) for 1-2 meters outside the control box (see picture below).

What is the best practice to connect switch to the microcontroller running at 3.3V? Simply connect one side of the swicth to Vcc and the other to a pulldown resistor? I fear that using a voltage as low as 3 volts will make it more likely that errors might occur: just 1V of interference induced into the wire will make it hard for the microcontroller to distinguish between LOW and HIGH. Should I apply a higher voltage, let's say 24V (that's the way the original datasheet states the switches should be used)? But in that case, how should the level conversion be done? A voltage divider would scale the error just as the signal, wouldn't it?

As you can see, I'm a little lost here, any help is appreciated. Thank you in advance!