texts: Is there an FPGA chip that has a built-in image sensor (or vice versa)?

texts: I would like to have an FPGA chip that is tightly connected to an image sensor. Ideally I would like to read all image columns (or rows) in parallel straight into the FPGA. Does such hardware exist?


texts: Puzzled with the result of LM317 constant current

texts:
So, LM317 can be used as a constant current regulator by adjusting the voltage in the Adj pin. The internal voltage reference is 1.25V, and so using a 1.25/0.900 ~= 1.4Ohm resistor and a constant current source of 12v, one would output a constant current of 893mA.

simulate this circuit – Schematic created using CircuitLab

At least in theory, and according to every site I read on the internet; however, I just did that and measured the current passing to the led: approx. 200mA!

What am I doing wrong?

Addendum: I'm using these type of leds, and I'm measuring the current passing between the limiting resistor R1 and the LED1.


texts: NC Opening Contact detector to drive a NO relay Contact circuit

texts:
I'm looking for a simple +5.5vdc powered circuit (perhaps a PNP transistor driving a NO Reed Relay coil?) - I need a circuit that can detect when a pair of Normally Closed contacts with no voltage across them at its input, then Open, and then a transistor? drives a NO relay coil to close a pair of contacts at the output.

I have a +5.5vdc source and 5.5 return pin available at the output relay side of the detector (so don't want to use a battery) and I plan to add the flywheel-diode across the coil and bias resistors but am not sure what wiring/ resistor values, or transistor type to use.

I have small a SPST-NO Digikey PN: 725-1354-ND 5V Reed Relay in mind but am open to substituting it with something else. If I could eliminate the transistor or the relay I would,  but assume I need something similar to detect and convert the OPEN contact state I'm monitoring into the closing pair of contacts that I need at the output to carry a very small current back into the equipment connected at the output. See this draft Rev2 schematic:

simulate this circuit – Schematic created using CircuitLab


texts:
I am very much a software person and a rookie in electronics.

I am trying to understand why do we need Diode D1 in the diagram explained in this post:

http://www.susa.net/wordpress/2012/06/raspberry-pi-relay-using-gpio/

I understand the need to the transistor to protect the GPIO pin; however, do we actually need D1? Is it a nice to have or if I don't use it, I damage my PI?

Thank you,


texts:
First, let me start off by saying that I have read the answers to this question (which is the same as mine), but the answers basically explain the different ways voltage is created or compare it to water in a pipe or altitude above the Earth's surface, so I was still a bit curious after reading those answers.

So, when I learned about voltage, it was often compared to height of a waterfall, pressure in a water pump, etc. The cartoon below helped me remember Ohm's law easily.

But, I want to to know exactly what voltage IS, not really what it's LIKE. As the top answerer of this question said, "If someone really wants to understand electricity, they need to dispense with the fluid analogies and just learn how electrical fields and charges work." So, I guess my question is: in terms of electric fields and charges, what exactly is voltage, what is happening in the circuit to make one point at a higher potential than at another, and why does increasing that difference increase how much charge passes between those two points, assuming constant resistance?


texts:
I need to design a current amplifier.

I'm sending a PWM signal from 0 to 5V that needs to be converted to 60mA at the maximum (so 5V). I am having trouble figuring out how to design this with either a BJT or MOSFET. I understand how both of them work except for the datasheets are confusing sometimes.

Any help is appreciated


texts: How do you use op-amps in a design in LTspice

texts:
How do you use an op-amp in a design in LTSpice?
I am trying to build my first circuit using an Op-amp in LTSpice, i.e., a subtractor.
However, do I need to build the circuit with my components around the op-amp model, as shown in image (1) or within its macromodel's test fixture, shown in image (2)? This is not quite clear to me. Please see below images!


texts:
`timescale 1ns / 1ps

    module Control(H, C, S, X, rst, clk);
    output reg[1:0] H, C;
    output [2:0] S;
    input X, rst, clk;

    reg[2:0] state, state_n;
    reg[4:0] cnt_12, cnt_34;
    reg[2:0] cnt_23, cnt_40;

    parameter   S0 = 3'd0,
                    S1 = 3'd1,
                    S2 = 3'd2,
                    S3 = 3'd3,
                    S4 = 3'd4;
    parameter   green = 2'd0,
                    yellow = 2'd1,
                    red = 2'd2;

    always @(posedge clk)
        if(rst) begin
            state = S0;
            cnt_12 = 5'd20;
            cnt_23 = 3'd5;
            cnt_34 = 5'd25;
            cnt_40 = 3'd5;
        end else
            state = state_n;

    always @(negedge clk)
        case(state)
            S0 : begin if(X)
                        state_n = S1;
                    else
                        state_n = S0;
                  end
            S1 : begin
                    if(cnt_12 > 1) begin
                        state_n = S1;
                        cnt_12 = cnt_12 - 1'd1;
                    end
                    else begin
                        state_n = S2;
                        cnt_12 = 5'd20;
                    end
                  end
            S2 : begin
                    if(cnt_23 > 1) begin
                        state_n = S2;
                        cnt_23 = cnt_23 - 1'd1;
                    end else begin
                        state_n = S3;
                        cnt_23 = 3'd5;
                    end
                    end
            S3 : begin
                    if(cnt_34 > 1) begin
                        state_n = S3;
                        cnt_34 = cnt_34 - 1'd1;
                    end else begin
                        state_n = S4;
                        cnt_34 = 5'd25;
                    end
                    end
            S4 : begin
                    if(cnt_40 > 1) begin
                        state_n = S4;
                        cnt_40 = cnt_40 - 1'd1;
                    end else begin
                        state_n = S0;
                        cnt_40 = 3'd5;
                    end
                    end
            default : state_n = S0;
        endcase

    always @(posedge clk) begin
        H = green;
        C = red;
        case(state)
            S0 : ;
            S1 : ;
            S2 : H = yellow;
            S3 : begin H = red; C = green; end
            S4 : begin H = red; C = yellow; end
            default : ;
        endcase
    end
    assign S = state;
    endmodule

The code can be simulated correctly and get the right figure

But when I try to get a bit fire and write it into my basys2, I got this error:

I don't understand cause when cnt_12 or other reg change when rst turn high at posedge clk, they can also be assigned at negedge clk, will posedge and negledge time contend ? how can I solve this problem or modify my code ?


texts: Current Transformers (CT's) wired in series for two meters or relays

texts:
I'm looking for a wiring diagram for the connection of two energy meters (or an energy meter and protection relay) in series to one set of 3 phase CT's, I've heard it can be done, is it S1 on the 1st meter to S2 on the second, should be simple right, as long as we consider the burden of the two meters and the burdern of the lead wires?

Or if we want to connect an energy meter and a protection relay is this 'not allowed' cause of the class of the CT's being different or if we get protection class 0.1 or 0.2 CT's, that is OK?

Please Help?


texts:
I am interfacing a 3X4 keypad to PIC16f877a uC on PORTD as:

In the first half of the C program I have set first four pins to Input (From LSB-RD0) and others to Output and store the value in a variable and in other half I have set last four pins to Input and others to Output and stored its value into another variable I have called this function in a continuous loop to get a pressed key.
The code is as follows:

int getKey(void)
{
    int toRet = 0;
    int firstHalf = 0, secHalf = 0;
    TRISD = 15, PORTD = 240;
    firstHalf = PORTD;
    TRISD = 240, PORTD = 15;
    secHalf = PORTD;
    switch (-((firstHalf + secHalf)-255))
    {
        case 20: toRet = 7;   break; //1
        case 36: toRet = 8;   break; //2
        case 68: toRet = 9;   break; //3
        case 18: toRet = 4;   break; //4
        case 34: toRet = 5;   break; //5
        case 66: toRet = 6;   break; //6
        case 17: toRet = 1;   break; //7
        case 33: toRet = 2;   break; //8
        case 65: toRet = 3;   break; //9
        case 40: toRet = 0;   break; //0
        case 24: toRet = 10;  break; //*
        case 72: toRet = 11;  break; //#
        default: toRet = 255; break; //null
    }
    return toRet;
}

The code is running fine on simulator but not on hardware it even doesn't generate any random key pressed. I am not using any pull up or pull down resistor because I think it may disturb the input mechanism.
What should I do to solve this problem?

EDIT: After abdullah kahraman's answer I tried adding pull down resistors of 10k ohm on all keypad pins but the problem is stil the same. Also in simulation (Proteus ISIS simulator) the code runs fine with a warning Logic contention detected on net on both pins input and output(+5V from uC) at that time. I am not using any pull resistor in simulation.


texts:
What is the Max value of Y cap (or what is max leakage current) should be select for EMI power Line Filter. understand increasing Y cap value will help to reduce Common mode noise but it will also increase the leakage current.

My product is Industrial grade, CISPR 11 CLASS A.

Thanks


texts:
I'm having trouble determining the value of the parameters of a LC Ladder Filter

Consider the available tables for designing second-order lowpass ladder filters (series first) with a Bessel response. The filter is terminated with resistors on both end with RS = RL/2. Find the values of the components parameters in order to obtain a filter with \$\tau_0\$ = 0.8 ms and adapted for a load resistor of 250 ohm.

So first I consulted some Bessel filter design table to obtain the normalized parameters
$$R_S=1/2$$
$$L_1=0.2601$$
$$C_2=3.5649$$
Then I performed the impedance scaling
$$R_S=1/2 \times R_L=125 \Omega$$
$$L_1=0.2601 \times R_L=65.025$$
$$C_2=3.5649 \times 1/R_L=0.0142596$$
Everything ok. Now the problem comes when I need to apply the frequency denormalization. I thought I just needed to multiply by \$\tau_0\$ leading to:
$$L_1=52.02 \space m H$$
$$C_2=11.49768 \space \mu F$$
Which is incorrect, as the values should be:
$$L_1=38.2 \space m H$$
$$C_2=8.378 \space \mu F$$
What am I doing wrong?


texts: For power pins of IC we add a decoupling capacitor, suppose a design misses the decoupling cap. Is there anything that can be done on layout to counter the missing decoupling capacitor? My first guess is to increase the width of the power traces.


texts:
I'm coming back to this design again after some time away from it. Previously I was trying to design the circuit to be completely passive, but that hasn't wound up being very reliable, so now I'm resigned to attempting it with an isolated power supply.

This little excerpt might be a little hard to read, but the "relay test" inputs each come from the load side of a contactor that switches North American split-phase 208/240 VAC (so each leg is 120 VAC from ground 180 or 120 degrees phase separated). The 150k resistor is a 1W flame-proof resistor, followed by a 1 mA current limit and a 1k resistor to ground. The voltage across the 1k resistor is compared to 1V. The output of the comparator isn't shown, but it lights an optoisolator that passes the status on to the logic circuitry.

The questions I have here are about the portion of the circuit shown.

Is the 1 mA regulator serving a purpose here or should I just remove it? My own paranoia led me to put it in to insure that if the path to ground was poor enough that any potential residual current would be limited to 1 mA, but the big series resistor is supposed to be guaranteed to fail-open, so there should be no way for its value to reduce by enough... right?
As designed, the comparator and its optoisolated output are completely isolated (one detail missing from the screen grab is that pin 8 of the comparator - its Vcc - is connected to Viso - the isolated +5 supply from DC1). Does this have any implications for the potential voltage the comparator could see if the ground impedance rose to infinity? Should I ground the isolated supply output? It's an isolated supply because I'm trying to insure that there's a good and proper "moat" completely around all of the HV circuitry. The one ground connection allowed is from the low side of the two 1k sense resistors in the GCM circuit. There are no other "exits" from the HV playpen other than components rated for many thousands of volts of isolation.

The goal here is to detect when the ground impedance rises above no more than 100Ω/V, or in this case, 24kΩ. The secondary side of the optoisolator has a peak-hold, so it's ok that only the peaks rise above the comparator threshold.


texts: tunable Wave form generator design with op-amps Multisim

texts:
I need to simulate a waveform generator using Multisim. I used the design in this Link. the frequency is 1KHz.
It works fine but I need some modifications:
1. I need the peak to peak voltage(Vpp) to be changeable so I did this
I got the right Vpp but the frequency decreased to about quarter of its original value. why did the frequency change?
2. I need to be able to change the duty cycle while keeping the same frequency so I did this modification
But unfortunately the frequency went up to 1.5KHz and the duty cycle wasn't the calculated value ( 2/12 )
For both issues, I am asking for an explanation and if there is a better way to do them.


texts:
I have two single-phase motors. This motors working in a fan. When I disconnect it from the mains and rotate it manually it produces 160V-190V.
The problem is when this generator runs manually and totally disconnected from the mains, I connect the two wires to Christmas lights and it lights up.  When I connect it to a 110V-220V appliance, the appliance did not work, the voltage (using a multitester) from the fan drops down and the fan seems to run from the electricity it produces.
I learned this from google and it says it's backfeeding.
Please help me to stop this backfeeding problem from an AC generator.
Electricity is always going back from its source, so I think the backfeeding is because the electrons is going back to the generator is why it is running from the electricity it produce, am I right? (I use this picture to describe the image of the problem in my head.)

This is the motor. I don't know what type it is.


texts: What is the need for amplifier stage in a data acquisition hardware?

texts:
Below is a typical data-acquisition block diagram:

As you see above after the multiplexer there is an instrumentation amplifier IA.

This IA stage can be shown in more detail as below:

Since this is a differential amplifier IC, its input stage must be a differential pair topology as follows:

Now my questions are:

1-) All the data-acquisition boards I used measured the actual voltage applied, and did not amplify them.
Normally if one sets the daq input range to -/+10V, and if one applies 2V with to daq's inputs, the daq will meaure 2V.
Here my first question is, what is the need for the IA stage if it doesn't amplify? Is that common mode rejection?
And what if the daq used for single-ended inputs? Would the IA still have a use? Why not directly coupled to ADC converter?

2-) If I swing the input voltage to the daq from -10V to 10V this is a large change.
Wouldn't it cause non-linearity in the IA's differential input stage(large-signal analysis)? How is  this be linearized?


texts: Making one usb headset work with two computers

texts:
I have a question about connecting one Logitech USB headset to work with two computers at the same time.  I would think this would be able to be accomplished in the same kind of way a KVM works but not sure.  I tried the basics of just splicing a usb cable together so it has two male ends and one female end.  This did not work so what I did was make it so one computer powers the usb headset and the data is sent down both lines.

Neither of these methods worked.  Does anyone have ideas on how to do this, cheaply, so i can use one headset across two computers?


texts: How can we read two digital inputs simultaneously from ATxMega128?

texts:
I am new here..

I have two IR sensors that give digital output (0 when there is something in front of it and 1 when there isn't).

I am using a ATxMEGA128 to run motors using these sensors but I am unable to read them simultaneously.

The way I am reading 1 pin is :

if(PORTD.IN & (1<<3))

this works perfectly fine but I do not know how to accept two inputs, For instance if my two sensors are on bit 1 and bit 3?

Can anyone please tell me the syntax?


texts: Using very low voltage from dimmer switch to trigger 12 volt supply

texts:
I have a new stereo head unit in my car that auto dims when the headlights are on.  The head unit does not have a variable dimmer, it is either on or off.  I have a dimmer switch in my car that is used for all of the internal panel lights.  I have measured the voltage from the vehicle dimmer switch as follows:

Position 0 is full brightness, position 7 is the dimmest (gray wire):
0 - 0.0 volts,
1 - 0.5 volts,
2 - 1.2 volts,
3 - 1.8 volts,
4 - 2.5 volts,
5 - 3.2 volts,
6 - 3.9 volts, and
7 - 4.6 volts

I measured the voltage of the headlight trigger wire that runs to the head unit and when the car is running it sits around 13.4 to 13.8 volts (orange wire).

In the past I have used relays for situations where I want an event to trigger something else, but through my research I am seeing that relays will require much higher voltage to trigger than I have. So I need a solution that allows for low voltage trigger, approximately 450 mV but, is also able to handle up to 14 volts.
 The solution also has to be able to handle up to 5 volts on the trigger side and wont lead to failure.  I have been looking around and it seems that a transistor might be my solution, although even reading up on transistors and watching a number of YouTube educational videos on the use of transistors, I am still not sure of how to wire one in, and or if it the best option, plus I haven't worked with current switches before.

Ideally I would splice into the gray wire and run that to my switch (part I am here asking about)  as the trigger, and then using the power from orange wire (vehicle side) as my power feed, then my output from the switch goes to the head unit.

Thank you in advance for any assistance!

Edit 1:
The radio head unit has an input power wire that is used to trigger the internal head unit dimmer. The power wire from the vehicle is at 0 volts when the headlights are off, and then jumps to 13.4-13.8 volts when the headlights are on.  So I don't believe the head unit can handle PWM. The dimmer switch in the vehicle has 7 different positions, with position 0 being all internal lights are at full brightness, and position 7 they are at the dimmest. I would like to trigger the head unit to dim at position 1 of the dimmer, but not have any damaging effects, if the dimmer switch were set to position 7. If that makes sense?


texts: What capacitor value to choose between the relay terminals for arc suppression?

texts:
I have an issue where I use a double pole double throw relay to switch between 170VDC and 120VDC. The issue here is that relay turns bad after switching a few times; I am guessing that it is due to arcing.
I plan on using a snubber capacitor between terminals for arc suppression.
How do I determine the value of the capacitor?


texts:
Determine if the system is stable?
How is this done? Is this at one frequency? Is the Loop gain is A x B x C = 0.5
Should phase angles be added together = 173 degrees?
Should I be considering the open loop or the the loop gain?
The only info i have been given in material regarding stability is that at any frequency if the loop gain is greater than 1 and the the phase lag is 180 degrees then it is unstable. The course is only an intro the control engineering but I have no clue where to start with this. The material is terrible and provides very little info.
This is the entire question. There is no other information with it.
Thanks all for your help


texts:
I derived electric field at a distance z above and perpendicular to the centre of a sheet as
E =
Now i want to approximate the sheet as a point charge and derive the electric field . I am not sure what am i suppose substitute in the equation
Can anyone explain the next step


texts: How can I measure the VBAT voltage throuth ADC of STM32F103?

texts:
I've got a board with a MS621 rechargeable backup battery. Some data should be kept in the memory after the device is powered-down.

Sometimes the battery will be discharged to a voltage below that which the STM32 backup registers require. In that case, I want to warn the user.

Therefore, I must measure the voltage of VBAT through the ADC of the STM32F1.

My question is that when STM32 is powered off (No VDD), will the connection between the battery and the ADC pin of the STM32 cause unexpected power consumption?

In other words, what's the state of the pin of the STM32 after the device is powered down? Will current drain from battery to the ADC pin of STM32?

Is there a better solution?


texts: Placing Input capacitor of boost after output capacitor

texts: I have a battery charger for 12V input with integrated buck that charges a single cell (3.7V nominal). The charger also has a power path and I would like to place a boost converter to boost the 3.7V to 5V. That means I am chaining a boost converter  after a buck converter (battery charger). How do I select and match the output cap of the buck with the input cap of the boost?


texts:
I'm trying to use a Teensy 3.2 to control a digital scoreboard display. I'm using 6 common anode 7-seg displays controlled by two 74HC595 shift registers daisy chained to control a transistor array. (Schematic attached).

I followed this tutorial to connect the shift registers to the board using 3 output pins. I have tested and mounted the circuit onto protoboard but I cannot get the displays to light up at all. (The Teensy is powering up and excecuting code correctly).

I have tested every connection between nodes with a multimeter and there are no shorts or missing connections, but no matter what data I send the output pins all read LOW when tested with a multimeter. I know the circuit should work as I tested a condensed version with one shift register and one 7-seg display on a breadboard and all worked fine.

I aim to multiplex the displays such that only one is on at a time (selected by the first (leftmost) shift register and the number displayed driven by the rightmost chip so each LED should be able to recieve the required current from the DC source.

The schematic and test code (just lights up one display) are attached below as well as the data for the components:

Transistors: 2N5210; Displays: SA40-19EWA (8V 20mA common anode);

Any help as to what could be going on would be really appreciated as I am relatively new to digital circuits

EDIT:

The schematic shows sets of 8 LEDs in series-parallel as one LED for clarity.

int dataPin = 3;
int clockPin = 5;
int latchPin = 4;

void setup() {
  pinMode(dataPin, OUTPUT);
  pinMode(clockPin, OUTPUT);
  pinMode(latchPin, OUTPUT);
}

void loop() {
  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, B11111111);
  shiftOut(dataPin, clockPin, MSBFIRST, B00010000);
  digitalWrite(latchPin, HIGH);
  delay(1000);
}


texts: Eddy current in transformer and its minimization

texts:
There is a loss in transformer that is known as eddy current loss. It also known as core loss. If we use solid metal instead of laminated layers of iron as core then the eddy current will much compared to the laminated layer.

My question is "What is eddy current? How it is produced in transformer? How laminated iron layers minimize eddy currents?"


texts:
I'm trying to make a little buzzer for my bike to sound occasionally to warn off bears. I have a 12V buzzer from Radio Shack (Cat. No. 273-065) and was wondering if I could run it off of 18V directly (2x9V Transistor Batteries series) for 1-2 second bursts, or if I should run through a lm317 which I worry might use more energy than the protection it provides. Are piezo elements relatively rugged when used like this?

Note: I can directly run the buzzer off 9V, with OK results, but I imagine 12V (or 18V) should be much louder.

Thanks!


texts:
Can you identify this component.  I think it is a fuse.

It is 5 mm long and 2.5 mm in diameter.


texts: How long can I draw 5 Amps from AAAA batery

texts: So this question might sound a bit weird, but if I had 14 rechargeable AAAA Battery strung together in series so the total voltage out put is 16.8 Volts, how long could I draw 5 Amps from the batteries before I cause damage to the batteries or the voltage drops below 15.6 Volts?


texts:
The USB charging port is on a AOBO spy camera, ive no charging cable and this doesnt appear to me to be standard.

Instructions with the device indicate it is a USB interface port. The instructions do not indicate which type of USB cable is required, but did originally come with one.

It's definitely not type C or B or micro B or mini B.

It also appears to be 8 pin

Any ideas?


texts: What type of connector do laptop webcam modules use?

texts: I'm trying to do a home practice with some used old laptop webcam, the model is "BA59-02608A" and it is from a Samsung NP-N150, it came without cable so I have no clue how could I connect to it, as I have never seen such kind of connector, I thought it might be a JST but I think I am wrong, I even asked Samsung but they didn't show much help.


texts: Issues with a Sallen-Key low pass filter for turning a PWM into a DC voltage

texts:
I need to turn a 490Hz PWM into a DC voltage using a Sallen Key low pass filter.
In the picture, you can see my bode plot and there is -60dB attenuation at 490Hz. The passband has 0dB of gain. The load is the 10k resistor. (Don't ask about the weird capacitor values it's what I got.)

The results from the simulator are perfect. For a 50% duty cycle I got an output voltage of 2.5V.
When I went to build this circuit here's the output I actually am getting:

Now I'm fairly certain that my circuit is working somewhat properly, because here is the signal at the positive terminal of the op-amp.It is a DC voltage of about 2.4V with a little ripple.
Here's what I've done so far to fix the problem:

Switched out the op amp for another one to see if it was just broken.
Checked to make sure that all of my wiring is correct (it is I've checked 100 times.)
Verified component values.
I've checked the signal at every "node" and compared it with my simulation. The signal at every single node matches up with simulation except for the output pin.

It feels like maybe the DC part of my + input signal is getting rejected and the ripple is the only thing getting through.


texts: Some problems with my dump load controller

texts:
The requirement is an automatic dump load controller; for balancing lead acid or lifo batteries.  While the input voltage is above 1.75V the circuit should dump 10A into the load continuously.

simulate this circuit – Schematic created using CircuitLab

So in theory (I think).  R1, R2, Q1 and Z1 form a variable zener trigger; switching on Q2 while the input voltage is above that set by R2.
Z2 should then sense the voltage across the load resistor; keeping current at 10 amps, by pulling Q2 low.

The problem is that I need to balance the batteries down to 1.75V, and the smallest zener I can find is 2.4 Volts.

Any other problems I'm not seeing?


texts: Confusion about ADR in ARM (assembly code)

texts:
I'm confused on what's happening with ADR R14,cnt1. Is cnt1 signifying the end of the program? And if so how will B sumi get called? In the ARM manual, it said that ADR takes in PC but I don't see that here.

c++:

s = 0;
for(i=1;i<=n;i++)
   s += i;

assembly:

sumi:
MOV R0,#0
MOV R1,#1

next:
CMP R1,R2
BGT end
ADD R0,R0,R1
ADD R1,R1,#1
B next

end: MOV PC,R14

ADR R14,cnt1
B sumi
cnt1: ; ...


texts: Parametric stabilizer circuit optimization for reducing ripple

texts:
We have a TV mainboard that will be used in cars. The input voltage will have lots of noise and not be regulated well. So we want to use a parametric stabilizer at the 12V input. Acumulator voltage may vary between 11V to 15.5V, we determined that we can accept input voltage levels between 11 V to 13.8 V and required current is 450 to 500 mA. Our stabilizer circuit do start to regulate input voltage when it exceeds 13.4V but with big ripples.

This is our standard Panel switch circuit in the red line and Parametric stabilizer which I added in green line:

The circuit in the red line is fixed standart power shutdown circuit of us and I can not make any changes on that. So I added the parametric stabilizer circuit in green line. The problem with this stabilizer is that it manages to trigger when the threshold is exceeded but it has enormous ripples:

Here the yellow line is output and purple line is voltage reference's output (pin 2).

The limitation is I can not use a DC-DC or LDO chip for this design (because they are expensive, this project is going for Mass production) and I have to implement this stabilizer with only components we have in our stock. So if you suggest any modification on this circuit or if you could suggest any circuit  for inside of the green line here it would be very nice. At this point I have to warn you that we do not use opamps! This circuit can be formed by only transistors, references etc. simple components.

What I have tried so far:

I tried a shunt 1 nF capacitor with R537: it did not do much, just made so little.

I took out input capacitor C1029: it made it worse.

I put 22 uF large output capacitor at output: did not make a difference.

I tried 1k-1pF RC compensation between cathode and reference: not much difference.


texts:
I've been trying to build a shunt resistor based current sensor using OP07. I've particularly chosen this because of its ultra low offset value. Its configured to be in differential mode as shown in the circuit below.

simulate this circuit – Schematic created using CircuitLab

The output is to be scaled from milliVolt range to 5v where the full scale deflection is set to be 5A -> 5v.

The problem I'm facing is the output is not scaling with the change in current. It gives out random values which almost has no relation with the input.
I've tried the circuit with low side sensing, high side sensing along with Non-inverting configuration.. All the circuits are tried separately and the output is not the expected one. Please help me understanding the issue.
Again to test if opamp is damaged, I tried voltage follower and it was working as expected and I tried with common mode(both inverting and non-inverting shorted to ground), the output comes to be saturated. Is this behavior expected?

Thank you for the help!!


texts: In the documentation of the DHT11 is said that it has sampling period of minimum 1 second. When I was using one DHT11 I could read new values exactly every 1 second or even less but on another DHT11 when the sampling period is 1 second I'm getting nan every to two measurements. The problem is gone when the sampling period is at least 1,2 seconds. Why is that different on different sensor or may the sensor be defected?


texts: How can i find the ESR of a capacitor using datasheets?

texts: I'm trying to find the ESR of the capacitor C0402C123K4PACTU but due to no avail, i can't find it. I've searched online on how to do so but all of the ones i've searched has a specific part of the datasheet that they can use to calculate the ESR, but this specific capacitor's datasheet doesn't have it (for example the table with tan(δ). Any help will be appreciated. Datasheets are as follows: data sheet for C0402C123K4PACTU and specification sheet


texts: I am trying to create a box that has a UVC light in it. I am going to have the light on the top of the box, this part will open up. The issue is the batteries and parts are at the bottom of the box with the other UVC light. So how do I wire it, because if I open the box then I have to pull on wires, and then if I close the box where will the wires go? Can anybody help me with this?


texts: Using mosfets to switch between two thermistors

texts:
I've got an Atmel ATmega328P and I'm trying to run two thermistors into one analog pin (TEMP_M5), using a digital pin to select which thermistor is active (TEMP_SEL_M5). I thought the circuit below would let me do that, but I've breadboarded it and while the right-half of the circuit seems to work when TEMP_SEL_M5 is pulled to ground, whenever TEMP_SEL_M5 is pulled high, the voltage at TEMP_M5 is 0 V.

Description of the circuit:

The lower half is the bottom half of a voltage divider.
TEMP_M5 is an analog pin.
TEMP_SEL_M5 is the digital selector pin.

My theory was that pull-down R27 would pull Q3's gate low, so Q3 would enabling TH_M5 to form the upper part of the voltage divider, while also pulling Q4's gate low, keeping thermistor Q4 inactive.

Can anyone point me in the right direction please? Or might I have an error on my breadboard (or both!).


texts: Getting temperature data from traditional pizza oven

texts:
I'm building a traditional Italian pizza oven in the back garden and would like to get some temperature data back to my home computer.  The major requirements for such a piece of kit are:

Record a temperature of at least 500c
Have reliable data recorders - once their set in concrete they're not coming out
Send data back to my house (which is out of wifi range)
Operate on battery power (edit: I'm happy to have a on/off switch but would like data every 5-30s when on and using the oven)
Operate in the UK climate, so be operable from around 0-30c, I can keep the box with the electronics under the oven so will be out of extreme cold/heat

I'm a programmer by trade so more than capable coding and building electronics.  I'm aware of the existence of Arduino but are also aware there are many other possible solutions.

My initial thoughts are a thermocouple with some kind of radio wave back to the house but that's pretty much where my limit of electronics gets me.  Can anybody give any pointers on typical setups that would fulfil these criteria?


texts: Which is the advantage of using an autotransformer instead of a simple inductive divider?


texts: An "operation" game sensor where the stylus is NOT attached to the power source

texts:
Edit: The person operating the catheter will be wearing latex gloves.  The only human tissue the catheter would touch would be that of the patient.  Also, to clear up some confusion about what exactly we're trying to, I included a picture below. The catheter is not threading through the dura, but outside of it.

So, we're designing what is essentially an operation-type game, with one major exception.  Whereas a normal operation game has both the tweezers and the metal rims attached to the battery.

Ours, however, is intended to function as a medical training tool. An actual stainless steel catheter or needle will be used, and we obviously can't hook that up to a battery.  Whenever the metal touches this long tube (your spinal cord, if you like the bio stuff), we're going to have an LED light up.

All of the information we can find about completing a circuit by touching something to it involves that something hitting in a precise spot to close the circuit. But we need to trigger the LED by touching ANY part of the tube.

We're planning on wrapping the tube in copper tape, in bands separated by rubber.  Our output is a row of LED lights, indicating the generally area touched (based on the bands).

Our only idea so far, in terms of circuit design, is to design a floating circuit and then use the catheter tip as the grounding element. Once grounded, the circuit will activate and turn on the LED.  Any idea if this will work or not?  Or any other ideas?  The only thing that cannot be changed is the medical grade stainless steel of the catheter/needle- all other materials are flexible.

Thanks!


texts: How to calculate power from this diagram?

texts:
I need to calculate the apparent power, active power and reactive power and I only got this diagram ( in german ):

So the equation for active power is $$P = \int_0^T u(t)i(t) \, \mathrm{d} x$$

Edit: Adjusted my solution to the answers:

$$ i(t) = kx+d = -{2t \over T} +1$$
$$ u(t) = 0.5 \rightarrow t=[0,T/2] $$
$$ u(t) = -0.5 \rightarrow t=[T/2,T] $$

$$P = {\int_0^{T/2}( {-t \over T}  +0.5 \,) \mathrm{d} t + \int_{T/2}^T ({t \over T} -0.5) \, \mathrm{d} t \over T} = \frac{1}{4}W$$

Complex power: $$S = RMS(i(t)) * RMS (u(t))$$
$$RMS(i(t)) = \frac{peak}{\sqrt{3}} = 0,577$$
$$S= 0,289$$
$$Q = \sqrt{S^2-P^2}= 0,144$$
$$cos(\alpha) = \frac{P}{S}= 0,866$$


texts: How to create variable clock frequency source in Cadence Virtuoso?

texts:
I am working on Delay Locked loop Project. I want to check the lock range of the dll. I am using vpulse for clock but by giving parameters clock period, clock width, rising time, falling time. It giving the clock pulse with same frequency.

I want the variable clock frequency. Is there another type of clock source which give me the variable clock frequency.

I am using Cadence Virtuoso tool and i am doing project in GPDK 180nm technology.

Anyone please help me to solve this problem.


texts: Efficiency of a multi-output power supply

texts:
I purchased a device labelled "AC Adapter" that labels the input to be 110 to 240 VAC, 50/60 Hz, 1.5A max and the output is labelled as 12, 15, 16, 18, or 19 volts, DC, 4.5A max or 20 or 24 volts, DC, 4A max. Physical dimensions of the plastic enclosure: 2 x 4 x 1.5 inches. The unit is surprisingly/very light.

The price of this new unit was 11 USD in a surplus store.

There is a slide switch for output voltage selection. This was purchased as a potential replacement for a power supply to a gaming console that requires 12 VDC, 3.5A. I will glue the switch at 12V to prevent misapplication. Given the range in possible outputs, will this unit be operating inefficiently at this extreme (low) setting?


texts: Why is it harder to turn the shaft of an unpowered stepper motor when connecting the terminals of a phase?

texts:
I experimented this phenomenon, but I don't know why. My guess is it has to do with back EMF, but I am not sure how.

I found it's also documented on wikipedia:

  (For the experimenter, the windings can be identified by touching the terminal wires together in PM motors. If the terminals of a coil are connected, the shaft becomes harder to turn. one way to distinguish the center tap (common wire) from a coil-end wire is by measuring the resistance. Resistance between common wire and coil-end wire is always half of what it is between coil-end and coil-end wires. This is because there is twice the length of coil between the ends and only half from center (common wire) to the end.) A quick way to determine if the stepper motor is working is to short circuit every two pairs and try turning the shaft, whenever a higher than normal resistance is felt, it indicates that the circuit to the particular winding is closed and that the phase is working.
  https://en.wikipedia.org/wiki/Stepper_motor


texts: Do I need to learn AC circuits for working with micro-controller projects?

texts:
I am a Computer engineering student. I am very interested in micro-controllers, FPGA, and digital design projects, and actually, I am good at these topics. In addition to that, I have a good knowledge of DC circuit analysis.

My problem is in AC circuits. I am just not that good at it. My question is: would I really need AC circuit theory as a computer engineer interested in DC electronics applications only (digital circuits, micro-controllers, FPGA, etc.)

I think once you feed a circuit with DC current through a power supply, from here on it is just DC stuff.

If the answer is “yes I need AC”, then how much of it (the required topics), do I need?


texts:
Are there any good references or simple tricks for making robust logic circuits?
I am implementing a critical decision circuit with a single 4-input AND gate and I am worried about something going wrong with it, and would like to do something simple to make it more robust to failure of the chip.

What I mean by that:
If you are clever with ordinary components, you can sometimes make more capable devices that no one ever really tells you about, or that you won't find in a textbook. For example, paralleling transistors to increase output current, or putting resistors in series (instead of using one resistor with the equivalent value) to increase voltage rating, or paralleling power resistors to increase power dissipation capability. I am looking for a similar concept, but for increasing the reliability of logic circuits.

I know about triple redundancy and voting circuits, but I am looking for something that won't require >3x the components.


texts: Adding ethernet ports - increase in gbps

texts:
I was wondering how this would scale. If you have one ethernet port on a device and it can handle 1 Gb/s - let's say - it can handle 1 Gb of data each second, right?

But if you add more ethernet ports, does the amount of data the device can receive increase linearly?


texts: Why do sensors or biosensors use AC excitation signal and not square wave signal?

texts:
I have recently started looking into transducers to measure a natural physical phenomena. The sensors I read about, especially electrochemical sensors like interdigital electrodes use a sinusoidal signal to enable the sensor electrodes. I came across this post, but it does not really answer my question.
Why do these sensors use sine signal but not square signal or even triangle waves? Perhaps some experimentation would help me understand what I would see on oscilloscope but unfortunately I do not have access to one at the moment or any electrodes to experiment with, hence my question.


texts:
The motor control for a small winch I have has the following diagram:

Note: (4, blue) and (5, gray) are connected together.
I do not understand what the voltage divider connected to the (4) connector is for?
Both resistors have the same value, which means that for an nominal input of 220VAC, the voltage at (4) is 110VAC.  Why is it connected to the output of the bridge rectifier?
EDIT:
I have disassembled the motor controller, here is an image of the voltage divider. It consists of 1/4W 120k resistors and it is clamped together to the varistor (DNR14D471K).


texts:
I have a question regarding the electricity generation using either steam or gas turbine.

After the process of gas or steam accrues and the turbine rotates. the turbine which is connected to the synchronous generator using a shaft.

Here I do not fully understand how the turbine rotation is converted into electric energy.

Could someone explain me the process, I want to know if the turbine is connected to the stator or rotor and how the magnetic field will be induced.

I hope my question is clear and thank you in advanced


texts: How does voltage splits when 2 devices was attached together

texts:
I'm new here and im not an electrical guy. Just trying to create some DIY stuff.

I want to know how to properly buy power adaptor for my newly purchased led light.

I have led light which is 12v and a 12v 2A power adaptor. This combination works OK so far.

Now I bought another led light and use the same power adaptor by commbining the positive and negative wire of the 2 LED lights which from my view works OK. No noticeable change in the light when powered ON

My question now

Does doing it this way divide the voltage that is being supplied to the led light to 2x6v or it is being supplied with 2x12v?

Is this the propper way of doing it or shall I need to buy another power adaptor per led light?

Thanks


texts:
Today I created this circuit and it works fine:

Now I want to replace the single LED with this row of LEDs:

But after this all the LEDs have a low brightness. How can I get back the brightness of the LEDs to a similar level to that of a single LED?


texts: Does layer order matter in a four layer PCB?

texts: The PCB doesn't have blind vias. In a four layer PCB the inner layers will often be a ground and a power plane. Does it matter which one you place closer to the component side?


texts: Is this a fake STM32F105? There is no parts listed with that many pins

texts:
I am working with a device that has a 100 pin qfp it is labeled:
ARM Z
STM32F105R8T6

But this part only seems to be available in a 64 pin package.

The R in the number dictates that it is a 64 pin package.

I don't think its mislabeled because I have three boards two of which were ordered a year apart and they're all the same.

Could this be some lame attempt to protect firmware? I can't really think of any other reason on why it would be done on purpose.

What could be going on here?


texts: Generating 40 kHz square wave using ATtiny13

texts:
I'm using an ATtiny13 running at 1.2 MHz and would like to generate a 40 kHz square wave on PB3 and PB4. The signal on PB4 should be 180 degrees offset (inverted) from PB3.

I know that I need to set certain registers to achieve this, but I do not know which registers or which values they need to be set at.

Any help with the code would be appreciated.

Update:

Thank you for the help so far. This is what I have got:

void setup() {

// Disable all interrupts
TIMSK0 |= (0<< OCIE0B) | (0<<OCIE0A) | (0<<TOIE0);

// Define outputs
DDRB = (1<<DDB4) | (1<<DDB3) | (1<<DDB2) | (1<<DDB1) | (1<<DDB0);

// Enable CTC
TCCR0A |= (1<<WGM01) | (0<<WGM00);
TCCR0B |= (0<<WGM02);

// 1.2MHz / 40kHz
OCR0A = 30;
OCR0B = 30;

// Toggle on Compare Match
TCCR0A |= (0<<COM0A1) | (1<<COM0A0) | (0<<COM0B1) | (1<<COM0B0);

// No prescaler
TCCR0B |= (0<<CS02) | (0<<CS02) | (1<<CS00);

// Make it start
GTCCR |= (1<<PSR10);

// Force one invert
TCCR0B |= (1<<FOC0B);
}

void loop() {
}

With this code, I am getting an 18.5 kHz signal on PB2 and PB1, with a 180 degree phase shift between them.

Does the code look correct or have I missed something? If I play around with the OCR0A and OCR0B values, I might be able to get the desired 40 kHz. However I should not have to do that, since 30 should be the correct value if the microcontroller is running at 1.2 MHz.

Any ideas?


texts:
Which way is better to feed the heaters of a vacuum tube on a guitar amp, AC or DC?

With the same transformer, is it possible to change between AC and DC supply for the heaters?


texts: Is a load needed to measure the voltage drop of a long cable?

texts:
Should be a simple yes or no question.

If I attach 20ft of 16AWG cable to a power supply, in theory I should see some voltage drop. Do I need to place a load at the end of the cable to read the actual drop or can I just connect my multimeter to read the end and take that as the voltage available.


texts: why isolate the run capacitor from circuit when off?

texts:
Back in 8/24/2016 Charles Cowie answered a question regarding a bidirectional AC motor with hand sketches. At the top left corner, the run capacitor for a motor with 2 stator windings seems to "always connected" between these 2 windings. In this case, why not have it hardwired and need only a SPDT relay that selects which winding get energized vs. using a DPDT relay.

But in more than one occasion, I have seen circuits with on-off-on switches, not relay, that always disconnects the capacitor between these 2 windings when the motor is off.  Is there a logical reason behind it?


texts: drilling SMT footprints for fitting THT parts

texts:
I have bought by mistake some THT caps instead of SMD and would like to use them still. They were bought from a supplier who has the bad habit of not answering customer requests. These are 5000h caps, costed me a few bucks.

I guess I could drill the SMT pads and iron solder the parts from above, inserting the soldering tip between the SMT pad and the cap's body. Any reason for not attempting this ?

edit


texts: Can I power multiple devices from one output of a power supply?

texts:
I am working on an LED project so I need to buy a power supply for powering some ESP32s and some LED strips.
During my research I saw Philips Hue's 3 output adapter, with which if you want to power more than one device you can use one adapter to power all.
I want to design an adapter like that which has 2 outputs for LEDs and ESPs and maybe add 2 USB ports to charge phones.
I found a power supply which has AC input and 5V 16A output.
This is power supply I found:

Also I drew a simple diagram (very simple) of what I want to do:

The LEDs consume a maximum of 3.6A at 5V, the ESP32 consumes not so much (not sure about maximum) and this power supply can give up to 16A.
All devices work at 5V.
Also I want to know if I can do this do I need anything like current protection module (I don't know if  there is anything like that) or a current limiter for USB output to charge phone. Is there any risk to phone?


texts: Necessary Bandwidth of Current Shunt Amplifier

texts:
I want to measure a bidirectional current using a Shunt and Current-Shunt Amplifier in High Side topology.
The ADC will work at a lower sample rate (<10 kSpS) than would be required for the faster parts of the signal (up to 500 kHz). Therefore a low pass filter between Amplifier and ADC will be used to prevent aliasing.

Would an Amplifier with a Bandwidth smaller than than the fast signal components but larger than the sampling rate suffice (without a noticeable impact on the measuring)?
The bandwidth of most Current-Shunt Amplifiers seem to be in the range of 100 kHz to 400 kHz.
Or do I need a Current-Shunt Amplifier with a Bandwidth of >= 500 kHz for this?
I am not sure here if the Amplifier behaviour can be regarded as a low pass filter like the frequency response suggests. See the Gain vs Frequency plot of the LTC6104 for example (Page 4).

One reason I am asking is, that so far I only found Current-Shunt Amplifiers with a Gain of >= 50 but low bandwidth available in stock. The LT1999 for example has a high bandwidth and is available with a Gain of 50 but needs to be sourced directly from LT or as non-stock from Digikey.


texts:
I'm kind of new to electronic and recently bought a Adafruit 9DOF Sensor. I use it with a Raspberry Pi Zero connected through I²C and when I try to read the Z-axis magnetic field data of the LSM303DLHC on it I always get 1111 0000  0000 0000, but the other axes output correct values.
To test it, I used a simple C code found on github, and after I got my incoherent result I searched on internet other ways to get them and tried for example using the address pointer of the chip but I got no better outputs.
The code I found (link):
    // Read zMag msb data from register(0x05)
    reg[0] = 0x05;
    write(file, reg, 1);
    read(file, data, 1);
    char data1_2 = data[0];

    // Read zMag lsb data from register(0x06)
    reg[0] = 0x06;
    write(file, reg, 1);
    read(file, data, 1);
    char data1_3 = data[0];

Is my sensor broken? Is there another way to get the data?
Thanks in advance for your response


texts:
I have a Sigma Delta Modulator with a SINC3 Filter. The System runs at maximum oversampling possible for this application and I know my (Full Scale Signal)ENOB for this szenario to be 14.

Is there any reason NOT to truncate Bits below thath threshold? The Target is a FPGA so keeping 2 more bits because a C variable is 16 bits large is no reason either. My guts says there must be some reason to at least keep "No missing Code" Bits, but I find no explanation other than maybe truncation adds some weird bias to a signed value or that I just dont want to surrender accuracy that wasn't actually there in the first place.

Are there any reasons to keep Bits below the noise floor, when further oversampling is not possible?


texts: Significance of gl/gG rating on circuit breaker

texts: I noticed that circuit breakers have a gl/gG rating. eg: gl/gG= 100A. Can someone explain the significance of this rating?


texts:
I made a little custom data logger.  It's powered by a rechargeable AA Ni-MH battery.

Typically, it lasts about 2 weeks on one battery.  Then it uses a low voltage cutoff to sound a low battery alert, after which I swap in a new rechargeable battery and pop the old one back in the charger.

A few weeks ago, I had a little minor problem where the whole thing got wet.  The battery was found to be pretty hot.  The data logger was completely destroyed and has since been replaced.  After the battery had cooled down, I put it back in the charger (BQ-CC17).  It seemed to charge normally, but I can't say for sure since that charger doesn't calculate capacity or anything.

I used the (potentially damaged) battery in the (newly replaced) logger.  It worked fine for about a week, then abruptly died (no low battery alert).  My speculation is that the voltage dropped off so abruptly that the logger didn't have much or any time between the low voltage cutoff and the battery dying completely.  (The logger worked fine after putting in a new battery).

So, my question is this:
Is it possible for a battery to "fail" in such a way that it shows the following symptoms:

Appears to work normally to roughly half its normal capacity
Voltage drops off almost instantly

If the battery were totally destroyed (internal short circuit), I would not expect it to work at all, certainly not for half the time it normally does.  Is there an "intermittent short circuit" failure mode, where e.g. the short circuit occurred based on ambient temperature/humidity/phases of the moon, rather than being related to reduced capacity?

P.S. Please, no answers telling me that getting a new battery is cheap and easy.  I already have.  I just need to satisfy my academic curiosity.


texts:
On one of my PC USB ports, I am using the power lines only, to drive a relay module that switches other devices on and off in sync with the PC.  This is working well.
The two data lines I have left floating, but I think they are getting stray interference that is bothering the computer, because for the first few minutes after power on, I get continual notification sounds of device connected/disconnected, before it gives up on that port and ignores it.
How can I terminate the data lines safely so the PC knows that there is no device active on it?  Should I:

connect them together?
tie them together with a resistor?
connect them to the power ground line?


texts: Sending 120VAC to a device for a certain amount of time after a single button press

texts: I am trying to use a push button switch to send 120VAC for a certain amount of time after it has been pressed. I want it to only be pressed once, and not have to be held in the closed position. Is there some sort of timer/timed relay I could use to accomplish this?


texts:
I have to obtain the pole of this circuit and the conversion function, but I can not do it .

How many poles does this circuit have?
And what are their relationships according to the arrangement of the figure above?
thanks ❤


texts:
Beginner with battery tech here, so forgive my naivety :)

I'm making a portable bluetooth speaker, and am wondering about the best battery solution to use.

The amp needs 60W max, and accepts 12-24V. I would like the charging circuitry to be contained inside the speaker so that I can simply connect a laptop PSU (19V) to a jack in the back to charge it. Ideally would like a runtime of at least 2 hours @ 15W.

At the moment I'm between Li-Ion and Lead-Acid (open to others!)

Essentially - which is the easiest/cheapest to install charging circuitry within the unit for? (I don't mind building a circuit but I'd rather not if possible :) )


texts:
I am using Arduino duemilanove and a Sharp gp2yoa21 sensor for proximity sensing.

Now i will be using it to calculate the distance as well so i need pretty consistent and smooth data. But i observe this periodic spikes (ignore the big spike) in my data. I even tried to used electrolytic capacitor to remove the spikes, still i can observe the same on screen (though this time its smoother)

I am using laptop to monitor the values(not connected to charging). Assembly is on breadboard.

Any guidance would be of great value. Thank you.


texts: Need help identifying power transistor 11SL60H

texts:
Hopefully someone can help me identify what these two transistor are.  I believe they're toast as the y open across all pins.

Normally I can google parts like these but this one I get absolutely nothing.  Not sure of the brand either.  It's on a Dell monitor switching power supply board by the way.  Thats why I believe it's a power transistor of some sort.  They trace directly into a TEA1716T control IC if that helps.  Of maybe someone can suggest a substitute.

Thanks in advance.


texts: Can you have general communication between an attiny84 and arduino without making attiny unreprogrammable

texts:
I have an arduino uno.   I have 4x attiny84.  now I want communication - general communication using usi and spi
protocol in a certain program between the arduino uno and attiny such that uno will be the  thing between  the tiny avr and my computer.  therefore I want to know if there is a way to do what I mentioned. I also want to know if the pins(those which are used for programming) are automatically initialized to their correct functions at a reset.


texts: Multiple data bit widths in a 4 bit adder?

texts:
So I am learning digital logic and have learned how to create an adder and have come across this question. So I am creating a 4 bit adder. To create the 4 bit adder I just make one 1 bit full adder and stack four of them together and flow the carry out into the carry in of the next adder. The two numbers (a and b) are represented into individual 4 bit segments, one bit for each adder. So a0 b0 a1 b1 etc...

Whenever creating the full adder into an ic and seeing images online, there are multiple data bit widths. So the chip says 4 bit adder and the two inputs have a slash through them and say 4. How would you physically implement this? Is this a symbolic notation so instead of having to say a0 b0 etc... everytime, you would just use the slash symbol with the number of bits? Bits are electrical pulses. The presence of electricity and the absence of electricity represented by 1s and 0s. So how can you implement 4 bits over one line? Is it somehow controlled by the clock? Can someone please help me any ideas?


texts: I2C protocol debugging using oscilloscope

texts:
We are testing an I2C accelerometer connected to the ATMega32A micro-controller. The accelerometer was working fine. We can write and read the registers using I2C protocol. When connected to the oscilloscope, we find it very hard to decode the signals to normal value.

We are just writing a value 0x08 (00001000) into the register 0x10 (00010000).

As per the I2C protocol, after the start condition we have to write SLA+W (slave address + write command). The 8-bit slave address with write command for the accelerometer is 0x30 (00110000).

I2C data must be like this

0 0 1 1 0 0 0 0       0(ack)      0 0 0 1 0 0 0 0     0(ack)     0 0 0 0 1 0 0 0     0(ack)

0(ack) is the acknowledgement of the I2C slave (accelerometer). Yet the signal we got from the oscilloscope gives no clue

The clock and I2C settings are as follows

Controller clock: 4 MHz internal clock
I2C frequency: 100 kHz
Pull-up resistors: 4.7 kOhms

Here is the image of the I2C-clock (Yellow signal) and I2C-data (Blue signal) lines.

I really need someone's hand in it to help in decoding


texts:
I am essentially intending to use this Schneider Electric A9F44120 MCB as an automatic brake for my wind turbine, which has an output of 25A @ 24Vac.
Can I use the normal 240Vac MCB for 24Vac?
Will it affect the current sensing ability or switching ability of the C.B? any suggests will be highly appreciated.
Thanks


texts: Working of bipolar junction transistor with electron flow

texts:
I faced a lot of problems in understanding BJT. I am going to share what works for me.
Suppose we take an NPN as the transistor in our case.
The emitter base region is forward biased, so electrons from emitter will flow in the direction of the base but since the the base region is lightly doped and is very thin only a very small fraction of electrons will recombine into the P region or contribute in the base current.
Most of the electrons will flow to the collector region and contribute to the collector current. The phrase "a small fraction of electrons" is very important.
Now we will deal with fractions so what is amplification? Amplification is the change in collector current with respect to change in base current. So what are the dynamics?
Suppose firstly the emitter was emitting 100 electrons in one second and the base current is contributed by one electron and hence the collector current is contributed by 99 electrons. Now suppose we want the base current to be increased so that it carries 2 electrons per second. To do that we need to increase the emitter current so that it emits 200 electrons per second. So what have we achieved? We got what we wanted in base current but as a result we also ended up getting 198 electrons flowing per second in collector current. So that is the amplification caused in collector current due to the change we wanted in base current.
Please correct me if I am wrong.


texts: What is the usage of Jumper1(JP1), Jumper2(JP2) and Jumper3(JP3) on the STM32F407 discovery board?


texts:
While scanning the VHF spectrum with a SDR USB dongle, I found something that sounded like an old 56k modem (at around 160MHz, FM modulation, Europe region).

After some research, I found out that is relatively common to broadcast digital messages and warnings with sound tones (ACARS)... so I decided to try to demodulate the signal.

With the help of minimodem, and after some trial and error baud rate estimation (1200 baud, ASCII, 8N1), I finally got some text out of those recordings:

CAL/I0M039D042#EXAN:09158700403:250/END
CAL/I0M042D039#OKEY:151/END

CAL/I0M055D053#EXAN:15171500380:244/END
CAL/I0M041D039#EXAN:10139400412:237/END
CAL/I0M039D041#OKEY:150/END

Anyone knows something about these messages?

Wheater forecast? Airport broadcast? Thank you.

UPDATE:

Thank you all for your comments.

I collected the signal for 24h, in order to determine if there was any kind of correlation with the weather (like temperature vs hour etc.). Afterward, I plotted the number following the EXAN keyword in the received string (here in bold: CAL/I0M055D053#EXAN:15171500380:244/END).

Here 4 of the resulting graphs (x-axis represent the sample number, not time). Judge by yourself:

As you can see, every signal seems to behave differently from the others, without any apparent correlation with wheater (pressure, temperature...).

I would exclude any boat tracking system because I live in a mountain valley, at least 80km from the sea. Moreover, the source does not seem to move and the packets signatures are recurrent day after day (at least for the moment).

PS: Thank you all for the interest, please feel free to move the question if inappropriate for "Electrical Engineering".


texts: Determining required signal SNR (beat signal from FMCW RADAR)

texts:
I'm trying to determine the SNR required for signal outcoming from FMCW Radar.
This is the chain: signal will created by "24 GHz VCO and PGA with 2-Channel PA Output" by triangle shape frequency domain, 8 dBm,250 max range.

Then received in this manner:

4ch 24GHz receiver downconverter ->
RADAR receiver path AFE: 4CH LNA & PGA ->
(Op-Amp) summer of 4ch together ->
(Op-Amp) sallen-key filter ->
Transmit to other board

Note: The AD817s Negative voltages is created by switching inverting regulator!

Seems I need to start through PA power then add max distance noise to it, then noise of receivers chain through their datasheet. Then some MATLAB simulation to determine least possible SNR required?


texts: How exactly does voltage drop across a component?

texts:
I have been doing some thought experiment and came across this interesting problem.
Say I have a standard normal wire that is 1 meter long, now I have a DC battery at some voltage level and I connect the positive and negative on each end of the wire. Of course, because of the low resistance of the wire, a large current will be drawn from the battery, causing the wire to heat up.
But here is the question, if I place a volt-meter between the positive side of the wire and to the middle of the wire, what will the volt-meter read? if we can assume the wire absolutely homogeneous in density across the span of the wire,  will it read half of the supplied voltage?


texts: mosfet to use with Raspberry Pi (3.3V) to trigger a 12v 10w led

texts:
I'm looking for a MOSFET to use as a switch to trigger a 10w - 12v LED.
1- I have acquired the module with the IRF520 but it seems that, even the seller tells that it is compatible with Pi, it is NOT as its max Threshold voltage is 4, so it would not fully turn on as the Pi gives only 3.3V. A lot of sellers tell it is compatible with Pi but when you look deeper, it is not. That is crazy !
2- Also, I already have another MOSFET: I don't know if I can use the FQP47P06 P MOSFET for this, as in the datasheet it talks about negative threshold voltages I cannot understand. If it is ok to use with my scenario, can you please give me indications about how to use it ?
3- Also I'm searching over the internet the FDN 337N, that would seem that it's the correct one, but I cannot find a place to order it from Spain without having to pay around 20 € for a single MOSFET (shipment costs) or having to wait months for it
Thanks in advance,
Roger


texts: Do dual-supply switch ICs provide DC Offset internally?

texts:
I am using analog switch ICs for the muting of audio sources, and am looking for some clarity on what I think I understand about them.

Below is a simplified comparative schematic of how I believe these switches can be used to yield the same function.

Where I Need Some Clarification:

Does the GND pin on the dual-supply IC provide DC offset, eliminating the need to do so for each switch channel?
If so, do the dual-supply switches still require AC coupling, or can they be used like a mechanical switch?
Bonus question: What is the purpose of VL? I read about it somewhere on EE.SE, but can't locate the question again. If it's not related enough, I'll keep looking.

I'm looking to minimize component count, as well as understand the differences in single vs dual-supply switches so that I can select between them. I've looked at the internal schematics and block diagrams in data sheets, and I see the connections, but am not 100% clear on what they are doing and how to exploit them.

EDIT: Forgot the links to Data Sheets

CD4066
DG412


texts:
Some background. I am attempting to build a oscillator circuit for use in HV power supply. Using a 555 to create a PWM to switch a MOSFET and then to either transformer or buck converter.
I have gotten the 555 to produce a clean square signal but the waveform output of the MOSFET is not a square wave. It is this:
This is the PWM:
This is the circuit I've made:
I have used 2 different MOSFETS and both give the same result.
What is causing the issue and what can I do to produce a nice clean square wave from the MOSFET?
Any help would be greatly appreciated.


texts: Debugging I2C, Effect of Oscilloscope Probes

texts:
Working on a simple I2C setup: Raspberry Pi connected to a WM8731 audio chip.  The Raspberry Pi configures the WM8731 (which is write only) over I2C.

Problem is WM8731 doesn't always respond with ACK.  I have logic analyzer attached to the I2C lines, and about 5% of the time the transmissions end in NAK.  No other devices are on the bus.

The curious thing is when I attach oscilloscope probes to the lines, it greatly increases the number of NAKs.  The scope shows nice sharp transitions on SDA and SCL, but sometimes the WM8731 just doesn't pull low for ACK.

What could be going on such that merely attaching the scope probes would make the problem worse?

Signals during proper transmission:

Signals during NAK:


texts: How can I modify this opamp circuit's logic

texts:
I need a system where it follows the input voltage below a set threshold voltage, and it outputs a set voltage above the threshold voltage.

Below is my attempt:

The circuit shown can output a set voltage(set by R1 and R4) above a set threshold(set by R2 and R3); but it outputs zero volt when the input is below the threshold voltage(i.e it doesn't follow the input)

How can I modify this circuit to make the output follows the input for inputs lower than the threshold? A diagram in answer would help better to understand.

Again the logic required for the system I need: The output follows the input below a set threshold, and it outputs a set voltage above the threshold.

Basically the input output will look like this:

Until a set threshold the output will follow the input; and at and above the threshold output will jump to a preset voltage.


texts: Olimex/ATMega328 Reading from UART and sending to USB

texts:
I'm getting frustrated with my electronic knowledge, because I want to do this simple thing:

Olimex 328/ATMega328 reads data from UART (Olimex MOD-PULSE or whatever) and forwards it to the USB Port (my computer).

I don't understand how I can do this. I wrote following program:

void setup()         // run once, when the sketch starts
{
  Serial.begin(9600);
  Serial1.begin(9600);
}

void loop()                       // run over and over again
{
  Serial.println(Serial1.read());  // prints hello with ending line break
}

But it doesn't work, since Serial1 does not exist. Could you give me a hint? I can't find anything that I can understand on the Internet.


texts:
I'm trying to Bild my own boombox with an 2*50W Bluetooth amplifier and 10 18650 cells with 3,4Ah each.
I habe bought a tp4056 charging board. The question is if i use 10 betteries connected in parallel and connect the minus and plus to my tp4056 board if it would be able to charge the safely. Or do I need a balance charger?


texts: How to create 1:4 Demux diagram using 1:2 Demux?

texts:
By 2m = n where m is the number of select lines and n equals the number of outputs (4) I found that I will need 2 select lines in total. But, I don't even know how to start drawing the actual circuit diagram using the base 1:2 demux, something that looks like this:

I'm not entirely sure on how I would chain 2 1:2 demuxes to create that 1:4 demux functionality.

EDIT: This is what I think it should look like


texts: How to use cy8ckit-041-41xx as a mutual capacitance sensor?

texts: I want to use the cy8ckit-041-41xx  as a mutual capacitance sensor. However, I am confused on how to proceed as I was unable to find any documentation or tutorials on how to use it as a mutual capacitance sensor.


texts:
I'm working on a two way amplifier/intercom for my parents to use in the car because of road noise and hearing problems.
I got a couple LM386n-4 and I've tried the circuit layout from here:
http://www.learningaboutelectronics.com/Articles/Microphone-amplifier-circuit.php

I've also tried the really stripped down version from this answer:
https://electronics.stackexchange.com/a/473553/76121

For a microphone I want to use a computer headset with ear cup for the speaker, and a boom mic for the microphone. It has a 4 section jack for left, right, mic, ground, and the plug also has 4 pins.
Unfortunately I can't get it to work. With one plug I get a weird tone, and when I tried a different one I only got silence.
I'm trying to get some electret mics, but I don't think I will be able to get them delivered in time for Christmas. So, is there a reason that the ones I have won't just work?


texts: Selecting capacitor for voltage-divider of half-bridge high power SMPS

texts:
How to dimension the capacitor for the voltage-divider of a half-bridge high power (>5KW) SMPS power supply?

The question is more on type of capacitor and current rating than the capacitance.

I have read some projects using electrolytic capacitors, even some computer power supply uses this approach and the capacitors are the DC Link ones too!

But as I know this is not a good choice, its better to use polymer, right?

But if you are lucky enough to find the manufacturer specifications, it's difficult to
get any info about the current the capacitor will support. Some papers says that's this is based mostly on dissipation of the capacitor, I have even made an spreadsheet to calculate that dissipation, I will post if necessary, but I didn't know if this is the way to go.

simulate this circuit – Schematic created using CircuitLab


texts:
I have a general purpose workbench that I would like to use for electronic work. It currently has a wood top, which I would like to protect (think varnished butcher block).

I have a small anti-static mat with wrist strap to use when working with sensitive components.

I would imagine that some sacrificial materials which I could use to cover this 2 x 4 foot bench are more ESD safe than others. Is this a factor I should consider when selecting what to lay down?

This is for home/hobby use but all the same I would like to follow best practice provided the cost is not excessive.

Whis is generally used for the top of ESD safe workstations? What would you recommend for hobby use that is reasonably low cost?


texts: Error handling in embedded systems development

texts:
I am developing a Firmware and I am using 3 layers: Driver, Platform and Application. In order to handle the communication between these layers, I am using an approach where each function will return a success/failure flag:

typedef enum {
  FW_ERROR = 0,
  FW_OK    = 1
}FWStatusTypeDef;

Every function in my FW looks like this:

FWStatusTypeDef function1(void)
{
  /* Do some stuff */
  ..
  ..

  if(something_wrong_happens)
    return FW_ERROR;
  return FW_OK;
}

FWStatusTypeDef function2(void)
{
  /* Do some stuff */
  ..
  ..
  if(something_wrong_happens)
    return FW_ERROR;

  return FW_OK;
}

The approach I am using is good for debugging but when running the application, I want to identify which function is sending an error flag. In other words, I want to keep track of errors and display them in a screen

Example:

FWStatusTypeDef OpenTheDoor(void)
{
  if (!KeyIsAvailable())
  {
    return FW_ERROR;
  }
  Door->Open();

  if (!DoorIsOpen())
  {
     return FW_ERROR;
  }

  return FW_OK;
}

FWStatusTypeDef KeyIsAvailable(void)
{
  return GetKeyStatus();
}

FWStatusTypeDef DoorIsOpen(void)
{
  return GetDoorStatus();
}

In this example, when I call OpenTheDoor() and it returns FW_ERROR. I won't be able to know if the problem is that the key is missing or there was another problem while trying to open the door (for example a cow is blocking it because it hates me).

I've been thinking and I came up with this solution: An Error code handler.

typedef enum {
  ERROR_1 = 0,
  ERROR_2 = 1,
  ERROR_k = k, // A cow is blocking the door
  ERROR_n = n  // The key is missing
}ErrorIdTypeDef;

static ErrorIdTypeDef ErrorCode;

// Getter
ErrorIdTypeDef GetErrorCode(void)
{
  return ErrorCode;
}

// Setter
void SetErrorCode(ErrorIdTypeDef code)
{
  ErrorCode = code;
}

Each function will use the error handler exposed Setter.

FWStatusTypeDef OpenTheDoor(void)
{
  if (!KeyIsAvailable())
  {
    SetErrorCode(ERROR_n);
    return FW_ERROR;
  }
  Door->Open();

  if (!DoorIsOpen())
  {
     SetErrorCode(ERROR_k);
     return FW_ERROR;
  }

  return FW_OK;
}

FWStatusTypeDef KeyIsAvailable(void)
{
  return GetKeyStatus();
}

FWStatusTypeDef DoorIsOpen(void)
{
  return GetDoorStatus();
}

In the application layer, I read the error code using the exposed getter API if an error occurs:

if (!OpenTheDoor())
{
  ErrorIdTypeDef theError;
  theError = GetErrorCode();
  switch(theError)
  {
    case ERROR_k:
      DisplayOnTheScreen("A cow is blocking the door.");
      break;

    case ERROR_n:
      DisplayOnTheScreen("You don't have a key.");
      break;

    ...
    ...

    default:
      break;
  }
}
else
{
  DisplayOnTheScreen("Door is open");
}

Now, my questions are not about the syntax, they're more about "good practices". Does this approach have any limitation ? Is there another known practice to get the same result ? In other words, Am I complicating things here ?


texts:
How can a 12V 80Ah Battery be 1800W? Shouldn't it be 960W?
I was looking for 12V 80Ah Deep Cycle Batteries on Amazon and most of them were 1800W.
Like this one: https://www.amazon.com/Cycle-Battery-RENOGY-SOLAR-PANELS/dp/B0143K89KA/ref=sr_1_fkmrnull_3


texts: A confusion on DC operating point in SPICE

texts:
LTspice calculates the DC operating points for the below circuit as as:

I have couple of questions here:

1-) If I would perform DC operating point for this circuit with pen and paper, I would first: short all the inductors and open all the capacitors. But then circuit becomes as:

But this seems wrong. What am I doing wrong here?

2-) In LTspice if we do not skip the initial operating point solution and obtain results, is that equivalent to: we first do a DC operating point analysis and we set uic for each component and do a transient analysis?


texts:
Please help look into to the below question where total dissipated power is to be calculated. In the solution given in the text they have added the under root of the power and then squared the result.

However, as per my understanding according to the superposition theorem you are not allowed to add the power together as it is not a linear quantity. Can someone help me explain why the powers are added the way they are in the solution is this an accepted formula. Thanks in advance.


texts: Find out the specs of a component without manufacturer

texts:
Today, I started playing with transistors. I have here some teeny tiny 2n2222-108 transistors.

Actually, it didn't take long before I burned my finger against that transistor... It was really hot. I guess my mistake was to assume that a 680ohm resistance would be enough for the base.

Obviously I can't keep working like an idiot, otherwise it won't be long before something really bad happens.

But I have a problem here: I purchased these components from eBay, and except from the 2n2222-108, I have no way of identifying them to find a datasheet. Turns out that looking for "2n2222-108" on google yield me way too many results.

So, given that I only have "2n2222-108" as identifier, how can I know for sure the limits of the component?

Of course this question does not apply specifically to this component. I may be in the same case with any other.


texts:
I have a transformer based AC fan controller (rated for 230V input) with five output steps ( 230V(5) - 200V(4) - 160V(3) - 140V(2) - 125V(1) ). I would like to have more fine grained steps, and am thus thinking to connect two equal transformers in series, giving me a total of 25 different steps.

The second transformer would then get as input the output from the first transfomer (125V-230V). Is it likely that this would work (assuming there are no other components inside the controller which requires 240V)? In other words, does a transformer work well with any voltage below the rated voltage?


texts: Can I use copper tape to connect Live AC power?

texts:
I want to fit a light on a wall in my flat, but there's no way of getting power cables discretely to it (I can't get to it from behind the wall, and the wall's not thick enough for me to embed a cable).

Looking for ideas online, it appears that someone has used adhesive copper tape, sticking strips to the wall to get the power where needed then painting over them.

Can I do this?
I guess I'd cover the tape with insulation tape before painting over.
If it is plausible, how thick/wide would the tape need to be to handle it?

FYI

UK Mains voltage: 240 VAC
Power light would use: 5-10 W

Thank you!

Lloyd


texts: Which standard use for custom communication DC

texts:
I want to transmit data and power over 10 meters at 12 volts with 1 amp. I don't know if I could do it using UTP, because that's a standard for other things. Which standard should I choose? Number of cables needed 4 at least. Frequency irrelevant, slow.
The question is; I'm not following the rules of UTP I'm making my own rules, so I suppose I cannot use UTP even if it fits my needs because if someone plugs a computer there it can be damaged. Is there a general purpose standard?


texts: Making an isolation transformer from two transformers

texts:
I've been reading up on isolation transformers and was wondering if I can set one up.  This question is somewhat related to [1] but without the centre-tap.
I have two 230V->12V AC transformers.  Having read [2], I understand that I can have the incoming mains go into the first transformer,  and have the secondary part be connected to the second transformer's secondary.  Then the second transformer's 'primary' is connected to the  unit in question.
In theory, I feel that it should work.  However, while the transformers have the label of '230V' on the primary and '12VAC' on the secondary,  I don't know the current rating.  Also the size of the two transformers are different.   I salvaged them from an old lighting system at work which powered a series of halogen 'spotlights' (the small round halogen lights that shines downwards... I don't know the right terminology for this).
Is this do-able?
Thanks
[1] - Connecting two center-tap transformers for isolation transformer
[2] - current transformer in reverse


texts:
I have been an EE for over forty years and never did find out the right answer to this one....

How do power-stations and transformer switching stations ensure that the power they are feeding into the grid is in-phase with the existing power on the lines.

I know they are VERY serious about setting the line frequency to a ridiculously good accuracy. However, obviously, you can not connect a power line to another line that is 180degress out of phase. Even a small deviation would presumably cause a huge drain on the system and generate a rather strange, and out-of-spec AC waveform.

OK I can imagine a solution at the power station that uses the target line frequency to synchronize the alternators before flipping the switch perhaps. However, that switching station 100km away maybe switching onto a line from a different alternator that is much closer or farther away and consequently at a different point in the phase cycle...

How do they do that...

Note his is NOT the same as "How to synchronize a generator on the electrical grid?" That article only pertains to a local generator and is not, in my mind, the same as the main power grid and transformer switching.


texts:
So, I'm making a custom PC case for myself. I want to add a simple on/off key switch (like all of the bikes have), only on ignition, start + restart button should work.

Here problem is that, I bought a ignition switch of some motor bike which has on/off as I wanted,  but when switch is ON, circuit opens, when it is OFF, circuit closes. (that's how bikes work, when switch is OFF, earthing doesn't allow bike to start. Similarly when switch is ON, earthing breaks and bike can be started.

I want to use this key switch in my PC. Are there any electronic parts that I can use in my case?

Such as if switch is OFF (here close)  but PC shouldn't start and when switch is ON (open) , PC starts?

Simple on/off key switch is not available at my place. I've searched every single store.

Here's a video about the switch I want.
https://youtu.be/fUeIVqdZyy4


texts: Voltage reference using zener diode and transistor

texts:
Below is a circuit presented in a book as a stable voltage reference circuit.

The other says that "Vref=Vz+0.6". I am not convainced about this equation, and I think that Vref is just VZ because of the virtual ground of the OPAMP. If I am not right, that means there is a trick in that circuit.

Please can anyone confirme to me the formula given by the other and how he did that ??


texts: Protection against EMI for an RFID reader

texts:
I've designed a base board for a Velleman VMA405 (13.56 MHz) RFID reader based on MFRC522 IC. But, due to interference from the base board (I'm assuming the oscillator), the reading range is limited to a few millimeters instead of a few centimeters. I'm in talk with a company that specializes in RF shielding and they offered me a few tapes that I can use to isolate the reader. But I don't know which one to choose.

My question is what materials can shield one side of the coil on the reader so that the base board does not interfere with the operation of the reader? Will this product provide the shielding I require?


texts:
I am trying to understand a grounding system for substations, fault current is something I am not getting. For example, for a small substation with some transformers, if there is a fault in the system how will the fault current flow into the grounding system? If the system has let's say 50 kA full fault current will all of the current (50 kA) flow into the ground or only certain percentage of the faulty current will flow into the ground?

How does this work? an explanation or link to explanation will be very helpful.


texts:
We have 2 Norelco smoke detector in the house. Early this morning, one of them began issuing short "battery is low" beeps every 5 minutes. The batteries for these detectors are 9v. I replaced the battery in the one that was beeping with a Gettop (Chinese) battery that I've never used for anything before. After doing so, the detector started issuing beeps about every minute. Thinking they battery must be run down or defective, I measured the voltage. To my surprise, it was 10v, not 9. I then checked to see if the contacts in the detector had become corroded. They hadn't. I then replaced the Gettop with a Duracell 9v, and the detector no longer beeped/worked perfectly.

Thinking perhaps that detector might have become faulty, I tried the Gettop in the other detector downstairs. Same result; immediately started issuing short beeps at 1 minute intervals.

Why is the Gettop unusable in these smoke detectors? Is it because they're intolerant of batteries putting out 10v (even though it says it's a 9v on the label)? Has anyone else had a similar problem with Gettop batteries?


texts: Interface between DAC and galvanometer board

texts:
I need to control with my Arduino some galvanometers I bought. The galvanometer driver board says it need to have a +-5V asymmetrical analog input.

My Arduino is connected to a MCP4922-E/P DAC from Microchip through SPI. The output of the MCP4922-E/P is between 0 and +10V (it can be between 0 and +5V if I don't enable the x2 gain).

How can I "lower" that signal to be between -5V and +5V? I've read the it could be done with some op-amp, but not sure how.

Any other advice about the design is welcome. Thanks in advance.


texts: Decimal addition using a different BCD WEIGHTED CODING

texts:
The problem that I'm having trouble in understanding is how the addition of two decimal numbers such as 17 + 4 can be represented using the weighted BCD CODE, [7 4 -2 -1] and binary addition techniques.

From what I have understood when doing BCD Addition using the [8 4 2 1] coding is that when the sum of a 4-bit result is <9 then the result is valid. When there is a carry from a sum into the next group of bits then we need to add 6 to the code in order to put it into 8421 code since BCD does not allow codes 10-15. The other case is when the 4-bit result is >9 then we will also add 6 to the bit to return it to the [8 4 2 1] format.

When trying this same logic on the sum of 17 + 4 = 21 I was not able to obtain the representation of 21 using the given coding. The answer should be:

0110 0111 = 21

My logic used for the question was the following:

I have read some further material related to the addition of BCD codes but closest I found was an example using Aiken-Code, [2421] coding.

Aiken-Code addition example


texts:
I've been trying to find the cause of power supply failures, and noticed that an NTC is smoking if it runs at full power.  Obviously the NTC needs changing.  But is it possible that the smoke in the chassis could then allow an arc to form between 400 V traces or components when it wouldn't otherwise?  Either carbon particles on the PCB or ions in the smoke.

  Particles from cigarette smoke or smoke after a fire can land on electronics and can cause them to short circuit.

from a dubious source

(Or maybe it's possible, but components are designed with materials that won't have this effect?)


texts:
simulate this circuit – Schematic created using CircuitLab

I have a 5V DC source that passes AC noise (alternator whine, spark plug discharge through the smoke-lighter-to-micro-USB port) in my A2DP bluetooth receiver, which passes it along to the headphone jack Aux input on car stereo. This A2DP bluetooth receiver it powers needs under 50mA, likely 20.

I want to make a low pass filter that will only pass everything under 200hz or so.
Modelling the 50mA load roughly as a resistor gives me a real component of 1k ohms, which requires a not-significant imaginary component (aka large inductor) to begin the attenuation at the pole where (R+jwL)=0.

What do I do about this? BTW, two doesn't really help.


texts: VCO from a rectangular and triangular signal generator

texts:
I need to create the simplest rectangular and triangular signal VCO I can using op amps. The output frequency should be changeable between 1k and 15k. I should also be able to change the amplitude of rectangular signal between 2 and 4 V. The triangular has to have the amplitude 5V. I was hoping I could modify this circuit by adding a DC voltage source somewhere to the V- input of the integrator, but I don't know how or if that's the answer to my issue. Can this circuit be modified for what I need or am I wasting my time and should look for something else?

simulate this circuit – Schematic created using CircuitLab


texts: Generating a (ideally several) PWM signal from GPIO, alternative to software-based pulse

texts:
Scenario:

I am trying to control precisely (without glitches) several servo-motors from a computer through GPIO. Final position, speed and ideally acceleration need to be controlled.

Currently I generate the PWM signal by software, but software seem not precise enough (due mostly to kernel context switches, the PWM signal is some times several micro-seconds late, producing some "shaking").
I know several way to improve, for instance implementing the signal from a driver (kernel) context, but the problem will inherently stay.

Question:

How to generate a PWM signal, based on software indications. Which solution is recommended?

Building the logic myself: That seem an overkill: 2 clocks, plenty of logical gates.. Even if probably achievable, the final result would take too much space.
Using an intermediate pic, dedicated to provide precise PWM, the protocol between the computer and the pic to be defined. Could be a solution, I am not sure however of the result or if there are better ways.
Looking over internet shops by PWM, servo controller, ... I did not found any chip which integrate this feature. Probably I miss an important concept.
other?


texts: Running 3,6V MCU on full 4,25V Li-ion battery

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How can I run 3,6V MCU on a fully loaded 4,25V Li-ion battery?
Normally the battery would be 3,6V, but on fully charged it is 4,2V, it would kill the microcontroller.

Load is 10mA, minimum voltage is 3,0V.

Is there a solution without any fancy LDO/IC?
Zener calculator said 3V is too low for Min input:
http://www.calculatoredge.com/electronics/zener.htm


texts: External oscillators for a microcontroller

texts: How do you go about choosing an external oscillator for a microcontroller, given the frequency you want? What's the difference between just a crystal (https://www.digikey.com/en/products/detail/suntsu-electronics-inc/SXTHM212AA164-16-000MT/12264644) and an oscillator (https://www.digikey.com/en/products/detail/suntsu-electronics-inc/SXO53C3A161-16-000M/12163949)? Why does the oscillator need a supply voltage? Most of the circuits I've seen that use straight crystals also have some capacitors connected to them, what are these for and how do you select their values?


texts:
How do I find S parameters from Z parameters, for a two port network.
I am sorry to ask such an elementary question but I am not from an engineering background. I have tried to search answers online but could not find it.


texts: What program would be appropriate for designing a reimplementation of the TurboGrafX16 at gate level?

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To be clear, I'm looking for a program I could use to redesign the TurboGrafX hardware at gate level, but to gate to gate, just for functionality.

Also, given that I'm interested in GPU design, what program do they most likely use for hardware design at a company like NVidia?

The only program I know of that could do this kind of thing is Logisim, which isn't industry standard, by a long shot.


texts: How do you constrain input delay for a multidimenionsal input vector?

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I am defining SDC input constraints for synthesis of a small module that is part of a larger ASIC design. I plan to run the module through synthesis using Synopsys tools. A few of the inputs to this module are multidimensional arrays. For example:

input signed [15:0] data_x [3:0][1:0],

data_x is a 3 dimensional vector.

For a vector such as

input signed [15:0] data_y,

to define the input delay, the constraint would be

set_input_delay -clock [get_clock clk] 5000 [get_ports data_y\[*\]]

However, for a multidimensional array input, the following wildcard setup does not appear to match the inputs:

set_input_delay -clock [get_clock clk] 5000 [get_ports data_x\[*\]\[*\]\[*\]]

The following works, but matches other internal signals in the design( such as data_x_d, which is undesirable):

set_input_delay -clock [get_clock clk] 5000 [get_ports data_x*]

Is there a way to specify the name with a wildcard to correctly identify all ports in a multidimensional array?


texts:
I have a LED controller that has several temperature sensors in different places of the system. I want to implement an overtemperature protection for the system.

Now this would be theoretically a simple excercise but the thing is that the system needs to keep on operating at a reduced output power when overheated. The ambient temperature load can vary greatly (sun/no sun etc). So the feedback needs to be proportional, simple hysteretic control will not do. In essence if the ambient thermal load is large enough to trip overheat protection, the system starts operating as an PI controlled unit with the limit acting as a setpoint.

I'm thinking of doing this with a trusty PI control sans the delta function. Is there any proven method of implementing this type of control which in normal operation remains permanently below the setpoint? If I do straight PI control the I portion will grow excessive and will prevent reasonable response to overheat condition.

I'm thinking of imposing a hard cap on "below setpoint" integral portion. For example it cannot exceed whatever 32 minutes at 1 degree below setpoint works out to. This would allow the integral to "reset" relatively quickly at overtemperature condition.

Is this a good solution?


texts: I assumed that a Schmitt Trigger inverter would act as an open circuit when unpowered, but discovered today that this is not the case. What does a Schmitt Trigger inverter act as when unpowered? I'm using the 74HC14.


texts: Why do I experience a voltage drop between logic gates when combining multiple gates (7408 and 7402)

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I am trying to combine logic gates (using ICs instead of trying to piece them together using transistors or MOSFETs).  Below is the simplest example of what I am trying to accomplish, though ultimately I would like to be able to combine 10 or more logic gates together in series.  In short, the problem I have is anytime I have an output from one of my gates it shows the appropriate voltage, but immediately when I connect that output to an input of another successive gate the voltage on that gate is almost cut in half resulting in the input being somewhere between high and low.  I looked at this post and read it over a few times, but am not able to apply the answer to my problem especially if I want to create a network of logic gates rather than just combining a NOR and NOT to get an OR.  I also don't have a firm understanding of TTL, which is why I am using IC packages.

simulate this circuit – Schematic created using CircuitLab

When I breadboard this out using +5V as high, I get something like this:

simulate this circuit

Again, when I leave the output of the 7408 open and look at the voltage it is 5V, but immediately when i connect that output to the input of the 7402, the voltage drops to 2.6V.

I have a feeling that I am missing something pretty basic here but have rebuilt circuits like this several different times with different gate combinations and see the same thing occur when I try to take a logic 1 output from one gate and feed it as a logic 1 to the input of another.

Am I using the ICs properly?  Can anyone tell me why the voltage is dropping between the gates?

Thanks for taking the time to read this.


texts: Best way to control 130 - 140 LEDS with Arduino Uno 32/64 bit led drivers?

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I am new to electronic prototyping and had a few questions.

I need to control 132 LEDs individually. I want to  make 3 rows ( 2 rows of 60 and 1 row of 12) I think i can matrix them but i would still need 63 outputs (3 high, 60 long).

I don't want to use 8 different  shift registers.
Are there any 32 bit or 64 bit led drivers(or shift registers, not really sure what there are called)
And where can i buy them.

Any help is appreciated .


texts: Is there any wire with many small wires which i can use for multiple video signal

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I have 6-7 cameras at one location. The problem is i don't want to have separate cable for 8 different cameras comming to my room.

I am looking for one big wire in which i can have small 12-14 wires so that i use pairs to carry video signal in one wire only.

Also my camera man was saying that we can use Cat6 cable for carrying 4 video signals with 8 wires. Is there any type of wire avaible with more small wires that cat6