texts: Handling of reset with multi bit clock domain crossing

texts:
I have an SoC design with two clock domains, each with it's own asynchronous reset (which roughly means asynchronous assertion of reset and synchronous de-assertion). I am trying to pass a 64 bit signal from clock domain C1 to clock domain C2, which is being handled through an async_fifo with fifo pointers being passed to individual clock domains using gray encoding.

Refer to this link for details on implementation

Let's assume the system wakes out of reset, all fifo pointers are initialized to zero, post that I send 4 transactions through async fifo, which increments the pointer values to 4 on both the side.

At this point, reset is asserted on clock domain C2, which causes read_ptr in async_fifo to go zero, but write pointer is not being reset and still hold the value 4, which results in empty signal going low. At this point my logic starts reading junk data out of FIFO.

One possible solution is to reset both write and read pointers, when one of the domain resets. But this needs reset synchronizer and some more combo logic on reset, and driving reset out of flops, which is not a good practice for DFT.

Is there any other way to handle this?


texts: Powering on specific pieces of circuitry in sequence

texts:
I'm trying to power on specific pieces of circuitry in sequence, and have one piece active at a time.  I thought a decade counter would be the way to go but most people seem to think a decade counter is a binary counter.  I'm trying to do this:

The best solution I've come up with so far is this:

Problem is this solution gets very resource intensive very fast, requiring more NOR gates for each line added.  What's the elegant solution for this?

Just to clarify, I only want one line active at any specific time.


texts: Can I use a simple fuse to protect a CMOS over current?

texts:
I'm designing an output with a MOSFET transistor to control loads such as relays, motors or incandescent lamps, similar to the outputs of a PLC.

Obviously, there is no problem as long as the load doesn't exceed the maximum current that the CMOS can handle. But there is the possibility that the user connects a load that the current to be circulated is greater than the allowed and that is where the fuse would act as in the following schematic:

simulate this circuit – Schematic created using CircuitLab

I think there is no problem with this design (obviously the fuse must be of some special character for inductive loads) but it is possible that something is not considering or it is possible that there is a better solution.

Any comments or suggestions are welcome


texts: I am measuring the admittance of a circuit, by switching a load off and on at different loads. The admittance value I got from the measured voltage drop and current flowing through my circuit. The problem is calculation is only good when the circuit is only resistive or having high power factor (0.9 to 1.0). As soon as the inductive impedance value goes up, the admittance measurement shows discrepancies. Can somebody please throw some light on it?


texts:
I have been given a small board which consists of 4 photodiodes and a precision amplifier.

To power the opamp I need to supply it with +2V and -37V according to the schematic I've been given.

Below is the schematic of the power supply that supplies this board and I was having difficulty understanding it completely

simulate this circuit – Schematic created using CircuitLab

The parts I think I understand is the 4 diodes that make the bridge rectifier. C3 and C4 are ripple smoothing capacitors and that V+ will be ~14V (10V x √2 - 0.7Vf) and V- will be ~-14V (-10V x √2 - 0.7Vf) although please correct me if I'm wrong.

The part I have trouble with is the voltage I've labelled 'X'. It has to be more negative than -37V otherwise the LM337 wouldn't be able to regulate it to -37V.

I'm going to make an assumption that it's something to do with C1 and C2 being connected to the AC input lines of the bridge made from the S1ML diodes connected to 'X' but I can't quite figure out the last bit myself.


texts:
I am working on a RGB LED Strip controller to light the inside of my PC. I plan to use a Molex connection 12V DC to power the circuit, the LEDs I am using can run up to 12V, but it should run at about 9V. So I need to drop 12V - 9V for that.

In controlling the LEDs I have designed a system using 3 potentiometers and a HEX inverting Schmitt Trigger to control the LEDs values. The IC runs off of 2V - 5V and need to control power.

I designed the system by combining this design, and this design, to power the LED strip and drop the power using a design I cannot find again.

(Note the LED in schematic is different from the ones actually plan to use, Ground in this case is meant to be +12V)

Before I go buy parts and start trying this, I want to get some better eyes on the project. I have yet to do anything other than messing around with an Arduino Uno and a breadboard to learn this stuff basically (I just figured how to use transistors as logic gates).


texts:
In the below schematic,

Photodiode is used ( not diode)

OP-AMP OPA 380

So, Vo = If X Rf

Case1:

IPh= A , Rf= 10K, VCC pin =5V

Vout = A X Rf = A(10K)

Case2:

IPh= A , Rf= 10K, VCC pin =3V

Vout = A X Rf = A(10K)

Does it means, Vout will be irrespective of VCC voltage?

Thank you in advance.


texts: Would connecting an amplified sound output to a line level input(aux cable) affect my car's stereo speakers negatively?

texts: My Bluetooth module has a built in amplifier and I connected the outputs to an aux cable and would like to plug it into my car radio, which also has a built in amplifier... I didn't think this was a problem before but it was brought to my attention on a previous question I had answered.


texts:
I need to find the inductor current for t > 0 and initial conditions as in example below. I think it's enough to divide V1 by 5*s and take the inverse Laplace Transform but my answer 3*e^-2*t - 7*e^-t + 4 is not the same as the book answer. It has +3 instead of my +4. It seems to be that book answer adds -1A initial current to my answer but I can't fully understand why it's so. It's clear that the original nodal equation was created with taking initial values of capacitor voltage and inductor current into account and it's not need to make any manipulations to current result, because the nodal difference V1 to ground already takes into account the existence of the inductor's initial current.

My solution is:

Multisim part of question is placed in another post: Multisim setup transient analysis with initial conditions


texts: how to find Thevenin Equivalent Voltage and Thevenin Equivalent Resistance?

texts: pls help me solve this question it’s confusing me


texts: Why would you short two pins of a potentiometer?

texts:
I've found a potentiometer which controls the heat of a cook top. One of the outer pins and the centre pin were shorted with a soldered jumper.
Why would someone do that? What does this achieve?


texts: I recently saw a video on khan academy which states that a capacitor acts like an open circuit. The video also states that the anode of the battery repels electrons and the cathode of the battery attracts electrons. How is that possible? I mean that electric potential provided by a electrochemical cell is the amount of energy per unit charge which comes from redox reactions. If the circuit is open there would be no redox reactions!


texts: what value is written onto microcontroller pins if i send the value as character type in Embedded c program?

texts:
#include<reg51.h>
     sbit sw=P1^0;
     sbit led=P1^1;
    void write(unsigned char m);
     void delay(unsigned char k);

     void main(){
      while(1){
        delay(60);
         sw=1;
         led=0;
         if(sw==1){
           delay(50);
           write(1);}
          else{
           delay(50);
           write(0);}
           }}

           void write(unsigned char m){
              led=m;}

           void delay(unsigned char i)
           { unsigned int k,l;
           for(l=0;l<=i;l++)
           for(k=0;k<65500;k++);
           }

what value is received by write function whether it is character or integer? i want to send integer value to write on led? is it right?plz tell me


texts: 'Time step too small' Error when simulating d-flip-flop in LTSpice

texts:
Im just looking to simulate a 3 bit counter in LTSpice and im receiving an error during simulation:
 Analysis: time step too small; time = 1.1e-009, timestep = 1.125e-019: trouble with d-flop instance a3
so the circuit im simulating looks as so:

and the clock/simulation parameters can be seen here:

where the voltage source parameters are as follows:

could anyone possibly give me some pointers as to why I might be receiving such errors and how it may be fixed? Thanks.


texts: I2C Master communication with a Ten bit slave

texts:
I have a doubt related to 10-bit mode of I2C protocol for multiple transactions with repeated start:

I would like to know how an i2c master / slave has to be designed to support 10 bit addressing for multiple transactions with repeat start (say to change the direction of the transfer) in between transactions.

Following is the scenario :

start + Read from a ten bit slave + repeat start + write to a ten bit slave + stop

As per I2C protocol,

Master-transmitter transmits to slave-receiver with a 10-bit slave
address. When a 10-bit address follows a START condition, each slave
compares the first seven bits of the first byte of the slave
address (1111 0XX) with its own address and tests if the eighth
bit (R/W direction bit) is 0. It is possible that more than one
device will find a match and generate an acknowledge (A1). All
slaves that found a match will compare the eight bits of the
second byte of the slave address (XXXXXXXX) with their own
addresses, but only one slave will find a match and generate an
acknowledge (A2). The matching slave will remain  addressed by
the master until it receives a STOP condition (P) or a repeated
START condition (Sr) followed by a different slave address.
Master-receiver reads slave-transmitter with a 10-bit slave address.
The transfer direction is changed after the second R/W bit. Up to and
including acknowledge bit A2, the procedure is the
same as that described for a master-transmitter addressing a
slave-receiver. After the repeated START condition (Sr), a matching
slave remembers that it was addressed before. This slave then checks
if the first seven bits of the first byte of the slave address
following Sr are the same as they were after the START condition (S),
and tests if the eighth (R/W) bit is 1. If there is a match, the
slave considers that it has been addressed as a transmitter and
generates acknowledge A3. The slave-transmitter remains addressed
until it receives a STOP condition (P) or until it receives another
repeated START condition (Sr) followed by a different slave address.
After a repeated START condition (Sr), all the other slave devices
will also compare the first seven bits of the first byte of the slave
address (1111 0XX) with their own addresses and test the eighth (R/W)
bit. However, none of them will be addressed because R/W = 1 (for
10-bit devices), or the 1111 0XX slave address (for 7-bit devices)
does not match.

From the scenario that i mentioned above, the first transaction (read) can be implemented as mentioned in the spec. Once there is a repeat start on the bus for second transaction, master has to put (11110xx0) for second transaction i.e. master write. But there can be many devices on the bus with the same 2 MSB bits which acknowledges it.
How can this scenario be handled ?

Also wanted to know how to perform a write followed by a read transaction with the repeated start for the same ten bit slave ?? (after repeated start (which comes after first transaction), are we supposed to send all 3 address bytes or only 11110xx1 address byte is enough).

Thanks in advance.


texts:
I'm new to fpgas, and there are some timing subtleties that I'm not sure I understand: if all my synchronous processes are triggered on the same edge, then that means my inputs are 'captured' on one rising edge, and my outputs change on.. the same edge? the next rising edge?

if I have two modules, where the output of one flows into the inputs of the next, there could arise the situation where the inputs to my module (the outputs of a previous module) are changing at the same time as they are captured.

The marker at 205ns shows what I'm talking about, op and data_write being my inputs. Everything seems to "just work" in this test case, but in the simulation it's not clear exactly what is being captured when. Is the data_write="0001..." being captured at 205ns or (205ns + 1 clock cycle)? Is there a way to get more detailed waveforms in ISim that show setup and hold times?

Thanks.


texts: Timer problem on STM32F7 - erratic behavior

texts:
First off I'm a complete n00b and just getting started with STM32.
I'm encountering some weird behavior while setting up TIM1 and also using external interrupt EXTI3. I'm attempting to measure a low input frequency on the external interrupt and using TIM1 to increment a 1 MHz counter, so I can measure in microseconds. I'm doing this as it seems SysTick isn't fast enough (1 ms) to give me an accurate measurement.

The core clock is 16 MHz, and TIM1 is set up as follows:

htim1.Instance = TIM1;
htim1.Init.Prescaler = 16; // 16 MHz / 16 = 1 MHz
htim1.Init.CounterMode = TIM_COUNTERMODE_UP;
htim1.Init.Period = 1; // 1Mhz no sub-dividing
htim1.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
htim1.Init.RepetitionCounter = 0;
...
HAL_NVIC_SetPriority(EXTI3_IRQn, 0, 0);
HAL_NVIC_EnableIRQ(EXTI3_IRQn);
...
void TIM1_UP_TIM10_IRQHandler(void)
{
    timerTicks++;
    HAL_TIM_IRQHandler(&htim1);
}
...
void EXTI1_IRQHandler(void)
{
    previousTimerTicks = currentTimerTicks;
    currentTimerTicks = timerTicks;
}
...
// Start the timer as interrupt
HAL_TIM_Base_Start_IT(&htim1);
...
while(1){
    // Blink a light so we know the program is running
    HAL_GPIO_TogglePin(GPIOB, Led_Green_Pin);
    HAL_Delay(100);
}

However, the program pretty much locks up and the while() run loop doesn't seem to execute. Yet, I can see the TIM1 counter is incrementing. If I slow the Period down to say, 100, the main application loop seems to run OK.

Is this a problem with TIM1 and EXTI3 conflicting at that speed - or something else going on here? I figure the device should have no issue providing a 1 MHz counter, but maybe I'm doing this all wrong.


texts: what inductors are used to reduce coil whine?

texts:
I was wondering about this after 2 years of heavy coil whine from a pS4Pro
PS4Pro power supply looks like the worst designed PSU ever made, and I'm aware some modern ATX PSUs have reduced close to zero the amount of coil whine by using inductors
what kind of conductors and how they are placed in the board I wonder?


texts: Arduino Teensy++ 2.0 PWM pins assignments

texts: I was wondering if anyone would be able to tell me what the pwm pin assignments for the Arduino Teensy++ 2.0. I have googled the assignments, however, I have tried two different boards and had an issues connecting to 0, 1, 24, 14, 15, 16 (as in they absolutely do not respond). We tried to use a different breadboard with no luck.


texts: How does one duplicate tracks on both sides in KiCad?

texts:
I have a problem: I'm making an Arduino shield that has tracks which are supposed to handle up to 10A (maximum, instantaneous) current (usually it's around 2A, but we want to be on the safe side.

KiCad calculated the according tracks thickness as ~11mm, which is huge for an Arduino Uno shield. Therefore, it was suggested to me to have two tracks on both sides, ~5mm thick each. However, when I connect two nodes with the second track, the original track gets removed, even if I lock it.

How can I get around this?


texts: how to create a circuit to represent x^2 +2?

texts:
and x would be a 3 bit variable

I tried to write it as a truth table, but then I would have the inputs from 0, to 7, and outputs from 0 to 51! Is there an easy way to do this?


texts: How to compare a re-writable 4 bit value to a given 4 bit input in Verilog?

texts:
The goal of this project to design a computational lock alarm in Verilog to be run on an Altera board (note on the board 0 is actually ON and 1 is OFF).

Based on the design criteria I created a state diagram of all possible states and contained them into a "cases" statement in my verilog code.

However, I'm having trouble comparing the inputted combination code and the registered password and ALSO rewriting a new password to the registered password when the design is in a particular state.

Note that I've included many of my troubles in comment blocks/lines.

/* NOTES: FIX THE PASSWORD REGISTER AND INPUTS*/

module combinationalLock (clock, INPUTS, enter, change, reset, door, newPass, alarm);

    input enter, change, reset;
    input [4:1] INPUTS; // I don't know if I've defined this correctly

    output door, newPass, alarm;

    reg[3:1] y, Y;

    wire[4:1] passwordREG; // rewritable and comparable to INPUTS (I don't know if I've defined this correctly)
    parameter[3:1]

    // Binary state values

    START = 3'b000,
    AGAIN = 3'b001,
    ALARM = 3'b010,
    CHANGE_OLD = 3'b011,
    OPEN_DOOR = 3'b100,
    CHANGE_OLD_AGAIN = 3'b101,
    CHANGE_NEW = 3'b110;

    // Default password combo

   passwordREG = 4'b0110; // IM TRYING TO SET THE DEFAULT PASSWORD HERE

    // State conditions and changes

    always @(INPUTS, y, reset, change, enter)

        case(y)

            START: if((enter == 0) && (/*INPUTS ARE EQUAL TO REGISTRED PASSWORD*/)) Y = OPEN_DOOR;
                     else if ((enter == 0) && (/*INPUTS ARE NOT EQUAL TO REGISTRED PASSWORD*/)) Y = AGAIN;
                     else Y = START;

            AGAIN: if((enter == 0) && (/*INPUTS ARE EQUAL TO REGISTRED PASSWORD*/)) Y = OPEN_DOOR;
                     else if ((enter == 0) && (INPUTS != passwordREG)) Y = ALARM;
                     else Y = AGAIN;

            ALARM: if(reset == 0) Y = CHANGE;
                     else Y = ALARM;

            CHANGE_OLD: passwordREG = 4'b0110;
                            if((change == 0) && (/*INPUTS ARE EQUAL TO REGISTRED PASSWORD*/)) Y = CHANGE_NEW;
                          else if ((change == 0) && (/*INPUTS ARE NOT EQUAL TO REGISTRED PASSWORD*/)) Y = CHANGE_OLD_AGAIN;
                          else Y = CHANGE_OLD;

            OPEN_DOOR: if(enter == 0) Y = START;
                         else Y = OPEN_DOOR;

            CHANGE_OLD_AGAIN: if((change == 0) && (/*INPUTS ARE EQUAL TO REGISTRED PASSWORD*/)) Y = CHANGE_NEW;
                                else if ((change == 0) && (/*INPUTS ARE NOT EQUAL TO REGISTRED PASSWORD*/)) Y = ALARM;
                                else Y = CHANGE_OLD_AGAIN;

            CHANGE_NEW: passwordREG = INPUTS; // NOTE IN THIS LINE IM TRYING TO REWRITE THE REGISTERED PASSWORD
                            if((CHANGE == 0)||(ENTER == 0)) Y = START;
                          else Y = CHANGE_NEW;

            default: Y = 3'bxxx;

        endcase

    // Clock pulse

    always @(posedge clock)
        y<=Y;

    // Output

    assign door = (y == OPEN_DOOR);
    assign newPass = (y == CHANGE_NEW);
    assign alarm = (y == ALARM);

endmodule

Note: I'm also getting some odd syntax errors at line 27, 47, and 59 where they expect an "end case".


texts: Kicad: Switching front Silk for Back Silk

texts:
I'm making a circuit using kicad and I want to add the silkscreen to it. It is a 1-layer board that I created using the front copper layer (red) of Pcbnew. The problem is that now the silkscreen doesn't match the physical layout of the circuit, because Pcbnew silkscreen output corresponds to the front silkscreen which fits perfect on the copper side of my board, but I want to stamp it on the other side. The board is already etched :(

So, my question is: is it possible to swap the Silk_Front and the Silk_Back layers, so that the silkscreen output file matches the physical layout of my circuit and I can stamp it on the fiber side of the board?

So far, I have tried the following methods to make the file matches my board:

1.- Importing the PS output file into Gimp: Really low quality.
2.- Editing with Okular: Doesn't have the option mirror or flip.
3.- Pcbnew layer swapping: Nothing happens.
4.- Mirroring the file with the printer settings: It can match the components, but the labels are reversed.
5.- PS->PDF then importing it into LaTeX, with mirror option: The same as 4.

I don't want to create the circuit again or etch the board again.
Thanks in advance!
Charlie


texts: Using Motor Oil as a Transformer Oil Substitute

texts:
I need a rather large volume of oil to insulate a few 15 kV wires/coils. Unfortunately, the volume of oil required puts transformer oil outside of my price range.

I've noticed that others have discussed motor oil as a fairly economical substitute that works effectively around this range.

Are there any types of motor oils and/or materials inside of mineral oil that i should be taking into account when selecting a brand of motor oil?

As some background, the materials I'm insulating are made of copper with a few jagged edges. There're also a few little electrolytic caps and inductors.


texts: I saw quite a few custom computer units and laptops that are powered by adapters/batteries totalling 18 to 24 V. What's the significance of this design choice?


texts: PWM, PAM, PCM sine generation and usage confusion

texts:
I am confused about something fundamental regarding PWM, PAM and PCM. I am going to be using a speaker's driver analogy to explain my point. As far as I know motors use PWM for power input, I don't know if my scenario with the speaker is any different but that's where it all began from.

As far as I know some DAC's convert digital signal to analogue signal using PCM. So you have pulses varying in amplitude being used as a carrier to represent a quantized signal (Fig. 1). That signal is then passed through a low-pass filter to interpolate the discrete pulses and get rid of the high frequency carrier. We feed the reconstructed signal into the speaker and we get clear audio.

                                          Figure 1

Then we've got PWM with varying duty cycle (Fig. 2). Let's assume it's Vhigh is 1V and its Vlow is -1V. By varying the pulse width in a certain order we can get a desired signal (a sinusoidal in this case) as we can calculate the average voltage of each cycle: Vavg = D*Vhigh + (1-D)*Vlow, where D is the duty cycle. The result is a choppy sine wave but a sine wave nevertheless.

                                          Figure 2

Now, this is where I am getting confused, sounds like a paradox to me. If I fed a PWM signal from Figure 2 into the speaker, what would happen? Would I hear a sine tone or the speaker popping as if it was being pushed back and forth? I understand that the average voltage comes to a sine wave, but if I connected an oscilloscope to the signal's output I would see a PWM, so what outcome would I get without any filtering or interpolation?

Similar thing with PAM, if we have 50% duty cycle and PAM pulses in a sequence of a sine wave, what would the speaker output, a tone or a popping noise?


texts:
I have found at some places, especially:

Raspberry Pi Forums

eLinux RPi Hardware page

the following wording:

  S2: DSI interface. 15-pin surface mounted flat flex connector
  (possibly no-fit) S5: MIPI CSI-2 interface. 15-pin surface mounted
  flat flex connector (possibly no-fit).

  P2: 8-pin 2.54 mm header expansion (header not fitted on Revision 2.0
  boards), providing GPU JTAG (ARM11 pinout, pin 7 is nofit for
  locating)

For a non-English reader this is not 100% clear. Could you please tell me what it means?


texts: Linear Regulator: Output current for stabilization different than datasheet?

texts:
TLDR; Why does my regulator require a minimum current for stabilization if the datasheet specs 0 mA as the minimum output current?

I have a strange situation that I've "found a solution to," however I'm not exactly sure why it worked.

I'm using the STMicroelectronics ST1L05CPU33R for a design I'm working on, taking 5 V in, 3V3 out. Nothing groundbreaking. I included the 4.7 uF caps as specified in the datasheet. Schematic (you can ignore the status LED and jumper I use as a test point:

The 3V3 load is a uC and some additional logic circuitry, pulling about 180 mA. I had 10 PCBs fabricated and assembled, and noticed on 3 boards that Vout is not always the 3V3 I am looking for. From the datasheet, my understanding is there is no minimum load current for voltage regulation:

However in tinkering around, I added an 18Ω load to the output and immediately saw the voltage stabilize. Take a look at the output vs input voltages for reference:

Am I understanding the datasheet wrong, in that a minimum load current is necessary for stabilization? Its even more confusing because certain PCBs work exactly as is, some don't. To be candid, I fear my assembler in China may use some gray market parts, but don't want to point fingers until I know for sure the mistake wasn't on my end.


texts:
We're communicating Arduino Mega 2560 I2C with MCP4728 and INA219
MCP4728 address are 0x60, 0x61, 0x62 and INA219 address are 0x40.
With 10k resistor as pull-up we're getting signals as below for SCL

Shall I change the resistor value?
(p.s. edit) Below are schematic portions

Any help would be appreciated.
Thanks in advance


texts: this is a super simple question. Does the diode work the same in this circuit if you place the motor after the transistor, instead of before? I'm trying to understand variations of where I can place the diode and how it really works. Thanks!


texts: Bad effects of coiling electrical cables

texts:
I have a desktop computer and a lot of external hard disk cases. I coiled all cables to make them organized and easy to clean. But an electrician told me; if you are using a cable, coiling (wrapping) cables is wrong. It could damage your computer, electronic devices, etc. You should un-wrap cables of devices if you want to use them. So;

Are there any bad effects of coiling electrical cables?

Note: I found this on a Stack Exchange site, but still I'm not sure enough: Physics of Coiled Cables

A quick answer that I learned; If cable is long and power usage will be high (up to 200 W), don't use a coiled cable. It melt and start a fire.


texts: I'm currently using the PIC18F45K20 for my project. I would like to know if there is any need of configuration of software if I'm using an external clock (8MHz crystal oscillator). The external clock I am using is 2 ceramic capacitor connected to the crystal and the other end of the capacitors are grounded. The software I am using is the MPLAB IDE X v 1.41. If a configuration is needed how do I configure the PIC?


texts: I am having difficulties in finding the DC component of the voltage across capacitor C2 expressed in terms of Vg and duty cycle D. In the first interval (DTs) the current through C2 is zero, hence the voltage Vc2 is zero. My problem is when analyzing it during the second interval (D'Ts). The voltage across Vc2 has to be ramping up or down but I have no idea how to proceed from there. I can't seem to apply charge balance to that cap. Please help. TIA!


texts: Using an Arduino Uno to program AT32UC3B

texts:
Is it possible to use the Arduino as a programmer for an Atmel 32 bit microprocessor? I have tried searching for something and was not able to find anything. If anyone could give any insight that would be much appreciated.
On a side note, I am looking to get this microprocessor (http://www.digikey.com/product-detail/en/AT32UC3B0128-A2UT/AT32UC3B0128-A2UT-ND/1769692)


texts: What is the difference between sCMOS and CMOS?

texts:
I am interested in microscopy applications, and am looking at both sCMOS and CMOS sensors as options.

Why are sCMOS sensors so expensive compared to CMOS sensors?  What are the benefits, and are they really worth the extra cost?


texts:
I use Stm32 and recently upgrading my design. Current product uses built in USB full speed and I do everything via this port. (Fw upgrade, service, other usual use cases).

In the new design marketing asked for Hs USB and I will add a ulpi phy to make stm32 Hs capable but there is a catch. The Hs operation doesn't allow dfu etc.

So, can I connect the dp/Dm from ha USB to FS port and use them together. The only time the FS port will be used is during dfu where the ulpi won't be working. As soon as the CPU boots I will make FS port high impedance so that it doesn't interfere with the Hs operation.


texts:
What would be a better heatsink to buy, copper or aluminum? What does copper do that aluminum doesn't? I know it is more expensive and is heavier, so what is the advantage of copper?

EDIT: more detail about the application. I need a heatsink for a TEG peltier module, the cool side. The source of power is simply the heat of your hand, coming from the hot side. To prevent it from neutralizing both sides of the peltier, I'm using heatsinks to cool the other side. Therefore, I need the most powerful heatsink available so that the peltier will produce voltage longer.


texts: Are ESD safe tools necessary with proper setup?

texts:
My current setup is an ESD mat and ESD wristband both connected via alligator clips to unpainted screws that are screwed into a secondary PC power supply (not mounted in a PC case.) This power supply is then connected to an outlet. Would this be a good solution to be safe from static discharge and component safety from it?

I use regular screwdrivers and some of them are from a gunsmithing set, some from an electronics set. Would these screwdrivers cause damage since they are not specified ESD safe? Wouldn’t me touching the screw drivers ground them to the same level as me?

Is this a good set up to prevent ESD damage to components?

Are ESD safe screwdrivers and tools necessary in this case?


texts:
I've built an amp using TDA2003. If I use a common 9V battery, it works nice, with very low noise.

But, if I change to a power supply (that I borrowed from a cell phone charger) that delivers 8.4V (1.7A), the noise gets too high. I can hear the noise even when the amp is playing. I tried to change the power supply, but the problem was the same.

So, It seems that the problem is with my power lines. I live in Brazil, and as far as I know, we use 127V/60Hz.

Searching the internet, I found that, in order to reduce noise, I should use decoupling capacitors. But the circuit already has two decouple capacitors: a 100uF (electrolytic) and a 100nF (polyester).

I'm just a hobbyist. I don't have an oscilloscope. Assuming that the circuit is OK (since it works with a battery), how do I reduce noise that is coming from the power lines? I was thinking about put an small extra cap (maybe ceramic), but I'm afraid to blow something.


texts:
I'm new in communication protocols and ICs. I would like to know if it is possible to connect a RS-232 (TX, RX and GND) to a RS-485 (Vcc, A, B and GND). I only need a half-duplex communication. The problem that I'm strolling around is that I need to enable/disable the RE and DE pins, to ensure bidirectional communication. How should I detect automatically the time to set RE or DE?

I want to design a PCB with a similar functionality as the transceiver below:

Does anyone have suggestions?


texts: Use power line to communicate between devices - simple communication

texts:
So I am a google programmer getting interested in hardware hacking.

What I want to do:
Use Arduino or a similar microcontroller to control the lighting in my house, of course for as cheap as humanly possible.

Proposed Method:
Using the power line itself for the communication (similar to ethernet over AC). A base station would be plugged into one power outlet in the house, that would send signals to N number of microcontrollers which are plugged into other power outlets. The communication between the devices needs to be very simple. Sending a packet containing the UID of the microcontroller to trigger, and command code (on/off). This command would trigger a relay to switch the power current on/off.

Reason for Proposed Method:
Most devices that do this use Wifi. Which having a Wifi device on every outlet would be very, very expensive. Having the base station only be Wifi would decrease costs tremendously.


texts: Terminology for referring to a normally open switch vs the normally closed setting it is used in

texts:
Is there some standard way to distinguish between the normal state of a particular component and the environment in which it is used?

For example, a reed switch would be considered normally open if it results in an open circuit when a magnet is not nearby.  If this switch is used in an alarm system to monitor the state of a door, however, it is likely expected that the door is usually closed which would put the switch in its abnormal state.  This means that the monitoring system is expecting that the circuit is closed under normal circumstances and alarms when the door is open.


texts: Problem getting correct output of filter in VHDL simulation

texts:
I have simulated a FIR filter. VHDL editor gives me no errors and compiles the code.
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.NUMERIC_STD.ALL;
USE work.types_numeric.ALL;
entity fir_filter_numeric is
    GENERIC
        (
          bits_data:           natural := 12;
          taps:                natural := 69
        );
    ---------------------

--<<<< hier die Namen der Ports festlegen
    Port
        (
        MainClk:                                    in  STD_LOGIC;
        Rst:                      in  std_logic;
    h :             in coefficient_array;
        sample_input:             in std_logic_vector ( (bits_data - 1) downto 0);
        sample_output:            out signed( (bits_data - 1) downto 0);
        FIRin:                    in std_logic;
        sample_out:               out std_logic
        );
  end fir_filter_numeric;

--! @copydoc    productDescription
  architecture Behavioral of fir_filter_numeric is

    type data_array is array (integer range 0 to (taps - 1))  of signed ( ( bits_data-1 ) downto 0);
  type mult_array is array (integer range 0 to (taps - 1))  of signed ( ( 2*bits_data-1 ) downto 0);
    signal shift_data    : data_array     := (others => (others => '0'));
  signal mult_data     : mult_array     := (others => (others => '0'));

  begin
     main_process : process(MainClk)
     variable add_data: signed (24 downto 0);
        begin
        -- synchronous_reset
        if rising_edge(MainClk)  then
          if Rst = '1' then                   -- do reset
          sample_out <=                                     '0';
      else
               shift_data    <=  signed(sample_input)    & shift_data( 0 to ( taps - 2));
              if FirIn = '1' then
                  -- count = 0, data_in
                  shift_data(0)    <=  signed(sample_input);
              else
                  -- (M-1)-zeros, count = 1:3
                  shift_data(0)    <=  (others => '0');
              end if;

               add_data := (others => '0');
               for i in 0 to taps-1 loop
                    add_data  := add_data    + mult_data(i);
               end loop;
               sample_output   <= add_data (22 downto 11);
                end if;
            end if; --

          end process main_process;

product_calc :
 for i in 0 to taps-1 generate
    mult_data(i)   <= (shift_data(i) * h(i));
  end generate;

    end Behavioral;

The simulation gives me an output  and to check if the output is correct I am going to send 1 as input.  If I send 1 ( in signal processing it is Dirac impulse I believe), I will get filter coefficients in the output.

Unfortunately I have gotten the wrong output.
Could someone help me to find where I have mistaken?


texts: What is maximum range of voltage measurement?

texts:
Another 'Basic EE' question here (from a mathematician).  Being rather ignorant of the matter - I would hazard to guess that there is some physical limit to the range of voltages that can be practically measured in an electrical circuit.  Would anyone know what that limit might be?

The terms 'practical' and 'electrical circuit' are meant to imply the context of an average consumer electronic device: ie computer/toaster/stereo/radio/etc.

For example: is \$-2^{100}\$V to \$+2^{100}\$V a range of voltage that can be accurately read?  (I'm assuming not but...)


texts:
I want to measure a low current (from 0 to 75mA) using the attached schemtaic for ACS712. The ACS712 sensitivity is 185mv and I want to use the max gain of 47 to input vout to a microcontroller(0-5vmax).

I want to make sure that this is how to correctly callibrate:

V=I x sensitivity x max gain
so when I is 0   V is 0
   when I is 75m V is 0.652125

Also I don't have any negative current so how do I connect the offset(R4)?


texts: Are there semiconductor materials with hole mobility greater than electron mobility?

texts: Every material I've ever seen has a hole mobility much less than its electron mobility. For silicon, it's by a factor of two or three; for gallium arsenide it's more like twenty. But are there any materials where the hole mobility is larger? Is it even physically possible for hole mobility to be larger than electron mobility?


texts:
I've been a long term desktop application developer and now I have the need to dive into embedded. What I am looking to do is implement a Zigbee mesh network where there is one co-ordinator interfacing with 9-27 'routers'. I have looked at various chips from TI and Freescale and narrowed it down to Freescale's MC13224 and since I am a n00b, I need some expert advise.

My question is, I have read through Freescale's Zigbee toolkit called Beekit and how I can use their desktop application to configure my Zigbee chip and then import those settings to my embedded project. What I don't understand is:

1) Will the chip come with some sort of BeeStack code on it? In other words, from a software standpoint, what work will I have to do to make Zigbee work for me on that chip?

2) If anyone has worked with this or a similar chip, can you guide me on what I need to do on my main MC to interface with this chip? Do I need to write some stack implementation? Does the MC13224 provide everything on the chip and I just read/write over SPI?

I'm basically asking a starting point for implementing this Zigbee chip with a main MCU. Please make the answer as layman's terms as possible since I have been learning embedded only for 2 weeks.


texts:
I have a very basic question about rf-electronics: I tried to understand how feed-through terminators work, but I could not find a wiring diagram online.
Intuitively it would make sense to me if such a feed-through terminator is equivalent to a t-piece with a termination at one end of it, e.g. for a 50 Ohm feed-through terminator I would expect to have a 50 Ohm termination at one output of the t-piece and the output-signal at the other end of the t-piece.
Is this a legitimate way of understanding this?
Thanks a lot for your help! :)


texts: USB-232 converters - rts/cts latency problem

texts:
I am integrating the USB controller FT230X into a new product.
It interfaces directly with the 32 bit Cortex M4 MCU, the STM32F303x

The receive buffer on the STM32 is only 2 bytes deep, which I assumed would not be a problem since I could use the RTS signal handshake to halt the receive stream.
However, when I send the RTS signal Hi automatically at the end of the first received byte, the data transmission from the FT230X continues for another 2 bytes, which causes an overrun.
Is this expected behaviour?
Is this a typical problem with USB/232 interface chips?


texts: Logic Level Translator with series resistors

texts:
I'm designing two MCU boards. These boards will be used for somewhat different purposes, but they should communicate with each other via UART. One of the MCUs has an I/O voltage of 5V, while the other has an I/O voltage of 3.3V. Thus I decided to use the push-pull logic level translator, TXB0104.

TXB0104 has 4-channels. I will use two channels for the UART lines and others for some simple GPIO lines. I'm going to mount the logic level translator on the 5V-compatible MCU board.

The problem is that I must protect all connectors from the ESD event. Of course, the connector for the UART lines should be also protected. The 5V MCU board should have its own protection circuit, and this is the same for the 3.3V MCU. Then is it okay that I put series resistors and TVS diodes to the UART lines in both of the boards? The datasheet of TXB0104 says that the IC can derive capacitive loads of up to 70pF. Can one use the circuit below without disturbing the operation of the TXB0104?

The line should have a series resistance of 400 ohms, and the length of the wires is about 30cm. I'm thinking of using NSP4201 for the TVS diodes. The configuration of the diode array is different from the schematic diagram above, but I thought it would not make difference.

Also, I wonder how people protect such logic level translator IC from ESD event.


texts: CE mark on a PCB sold as a part of a kit or part of a project, necessary?

texts:
I've a prototype that I want to sell as a product. My prototype is made by an aluminium structure, a motor, a moving part (made by 3D printer) and an electronic circuit.
The electronic circuit is made by an Arduino, a motor shield and a simple PCB on top of it (the green one in the image)

The only parts that I've exclusively are the aluminium structure, 3D component and the PCB.

Should I CE marks the PCB if:

I sell the entire product as a kit?
I sell only the exclusive parts, making available instructions to mount them with other components (not sold by me)?


texts:
As part of a school project, I need to measure milliseconds from the start of a timer. I will need that value to later process it, subtracting and adding it later multiple times. At most the timer will last 5 seconds.

I have a clock signal with a frequency of 1kHz, what component can I use as a counter?

In school we've studied the theoretical components, but I need one(or more) actual IC that can count up to 5000 (probably 2^13). The only operations i need to do are add 1 and reset.


texts:
Is it possible to create a Karnaugh Map when there are two outputs, the examples I have seen are all one output. If it is possible, what is the process to convert a truth table like this to a k map? If it is not possible, are there any processes like a k-map I can use to help simplify the truth table?

For Example:

A,B,C|OutA,OutB
0,0,0|0,0
0,0,1|0,1
0,1,0|0,1
0,1,1|1,0
1,0,0|0,1
1,0,1|1,0
1,1,0|1,0
1,1,1|1,1


texts: Quartus ii - How to manually set coordinates of blocks or elements

texts:
I am trying to implement TDC on Altera FPGA so i need to make carry chain with carefully placed delay elements. I was searching and found a lot of examples for XLINX where manually placing of elements is done with attributes which are given to wanted element. One of the examples is below:

ATTRIBUTE LOC OF delayblock : LABEL IS "X_SLICE"&INTEGER'image(Xoff)&"Y"&INTEGER'image(Yoff+i);

Quartus ii compiler can't recognize such statment. On other hand i didn't found any examples for Quartus.


texts:
I have problems with Arduino Mega drivers on Windows 7.

I've downloaded  newest driver from http://www.ftdichip.com/FTDrivers.htm, but i cant install driver.

I've installed  USB Serial Converted, but USB Serial Port dosen't work (i tried to reinstal driver, but it don't bring any effect).

I've used this below instruction:

In Windows 7 the FTDI driver is plug and play (windows should identify that it has been plugged in and
can automatically download/install the correct driver)
If this doesn't work download the FTDI drivers from: http://www.ftdichip.com/Drivers/VCP.htm
Make sure you're using the latest JRE in 32-bit (even if you run 64-bit)

.... and it doesn't bring any effect too. Could you help me?


texts: Is it possible to make a keyboard with "Game Controller" style printed circuit boards and buttons?

texts:
For a long time I've wondered if it's possible to make a keyboard with PCBs similar to the ones used in NES controllers or just video game controllers in general. If it can be done with keyboards it'd be cool to do the same for a mouse or something, replace the clicky switches inside with 3 small button PCB, one for the left, right, and wheel clicks.
Anyway, I want to know if this is or has been a thing, if it's even possible, and if people make these so I can buy one, or better yet make it myself. I'll be honest, I love membrane keyboards more than mechanical (I know call me crazy) but I love the feeling of NES, PS1, and Xbox Controller buttons a lot more.
I was thinking of making long strips of PCB (or buy custom PCBs) with the button pads similar to the one on the image above, buy button contacts and modifying an old keyboard I have laying around. It seems to me like an easy enough job to do.
Another question I have is, if this has been possible, why haven't companies made keyboards like this yet? Would it have to do with the cost of making such a thing?


texts:
I'm finding that some GPSs (e.g. Garmin nüvi 2300) have a "HotFix" feature that causes satellite connections to be made more quickly.

How does this feature work? Is it internet/WiFi-based, is it similar to WAAS, or is it something else?


texts: Confusion in sync-async transmission in RF circuit

texts:
I am learning about building an RF transmitter circuit. Now one answer in Answer to DIY RF Transmitter Circuit specified " Very first thing you have to decide on data is whether you want synchronous/asynchronous one. By which I mean the local sine wave oscillator (stage 2 above) are in phase or not."
So, my understanding of synchronous-asynchronous comes from using a clock. For example we use clock in sync-counters, so we say outputs of each flipflop is in sync with the global clock(one clock). In async-counters, we say output of each clock, in some sense, is in sync with the output of the previous block(because output of one flipflop is fed as clock into the next flipflop) and not a global clock.
Now, in above RF transmitter circuit, say my data is 1010, say I converted it into a signal like square wave where 1 becomes 5 volts and 0 becomes 0 volts and the signal has a period of 2T where T is duration for high and low in signal. I modulate it on the carrier signal generated from oscillator and I send it. When I am sending the signal then I should receive it in same order, right? Because my Left Most Bit(0) left first from transmitter side and I should receive it first at receiver side. The notion of asynchronous or synchronous does not make sense here to me.


texts: Programmer for MSP430F2274 TI microcontroller

texts:
I want to program that specific microcontroller (MSP430F2274) and i would like to hear your opinion on what programmer to choose . I prefer one that can be used with a linux machine.

So what you suggest me ?

Thank you.


texts:
In a boost converter, what is the factor that determines whether the power supply (dc-dc converter) will be in the CCM, BCM or DCM mode?
Because, I have an LED Driver A80604. And I am trying to calculate the inductor value for it.
Input Voltage = 9.5V to 16V
LED string = 9 LEDs (each Vf of 3.1V and If=0.3A)
Output voltage = 30V
Output Current = 300mA
In this case, I have been following the design example from page 35.
I have got to this point :
Vout_typ = 30.64V & Vf_schottky=0.52V. Vbat = 9.5V, 13.5V & 16V (Min, typ and Max)

Are my above calculations, right?
My questions:

What is the factor that determines whether the power supply (dc-dc converter) will be in the CCM, BCM or DCM mode?

What is the required inductor value that I need to choose for this application which requires constant current for the LEDs?


texts: Getting different measurements from power supply vs a battery

texts:
to start with, I am very new to the hardware side so don't beat me up too much.
For a project I am doing I need to build a couple power rails, one 3.3v and another 24v. The power supply will be from a 3.7v 1A LiPo battery.
I started on the 3.3v first, I already had a 3.3v fixed voltage regulator (L78L33A), so I figured I could probably just use this, in the datasheet showed a schematic but didn't have the zener diode and resister values and I don't yet know how to calculate these so I figured I would just play around with different values to see what I could come up with.
I set my benchtop supply to 3.7v, 1A for testing and after playing around a bit I got a nice 3.3v output, still don't understand it but eventually I will learn.
Then, I hooked up the battery and did not get the same 3.3v output, instead it was much lower and when I probed right at \$Vin\$ with the battery in, I would get ~2.5v, however, when I probe the battery without it hooked up to anything I got ~3.9v.
I'm wondering why the results are different and if this is normal to have the different results? If this is, then should I have instead tested using on the battery since that is what it will ultimately be running off of?
Here is the schematic with the values I ended up with (I will start a new question about how to figure out Vz/Vx/R1).

Thanks!
Update 01
Based on the answers and comments, clearly this is def wrong for what I'm trying to do, I was reading the schematic for a boost circuit, will take the suggestions and try this again.


texts:
I setup TIM3 on my STM32F411 using the following code:

void Enable_Timer_3()
{
    __TIM3_CLK_ENABLE();
    TIM3->PSC = 8399;               // Prescaler value, 8400 - 1, 84 MhZ / 8400 = 10000 Hz
    TIM3->EGR = TIM_EGR_UG;         // Update prescaler
    TIM3->ARR = 9999;               // Period, 10000-1, 1 second period
    TIM3->DIER = TIM_DIER_UIE;      // Enable interrupts for this timer
    TIM3->CR1 = TIM_CR1_CEN;        // Enable this timer
}

The timer counts just fine - inspecting the TIM3->CNT register shows it correctly counting from 0 to 9999 in the span of a second. But my interrupt handler is not called.

My handler:

void TIM3_IRQHandler(void)
{
    TIM3->SR = 0;
    HAL_GPIO_TogglePin(LD2_GPIO_Port, LD2_Pin);
}

It is set as the TIM3 interrupt in the interrupt vector:

  .word     TIM3_IRQHandler  /* TIM3 */

Did I do something wrong?


texts: What is the FTDI config for a Numato WaxWing Spartan 6

texts:
Unfortunately I've overwritten the configuration of the FTDI chip on my Numato WaxWing Spartan 6 FPGA development board.
I've managed to reset some values back, so I can at least communicate with it, but don't know what I've missed.

I have the ability to set values as I want, but don't know the correct values. Can someone answer, what is the output from "lsusb -v -d 0403:6010"* for a factory configured Numato WaxWing Spartan 6 FPGA development board?

* I think these where the original IDs


texts: IR Reflectance Sensor for a Wheel Encoder - Analog or Digital?

texts:
I'm in the process of building wheel encoders for my robot and have come across 2 different IR Reflectance sensors.

Analog
Digital

I'm trying to find out what the potential benefits or drawbacks of each one would be and what I should use for my project.

With the digital one, I presume I will receive a HIGH/LOW reading but I will have no way to adjust the thresholds. Would this eliminate noise as mentioned in this answer?

With the analog one, will I have more control over what's supposed to be HIGH/LOW? Are there benefits to going the analog way and handling the signal through code?

At the moment I'm inclined towards purchasing the digital one for the sake of simplicity but I'd love to hear what you have to say on the matter.


texts: Can the electron source be known as the anode in one place and the cathode in another?

texts:
It is my understanding that in a Galvanic or electrolytic cell the electrode from which the electrons flow is known as the anode.  Yet it is also my understanding that in a vacuum tube the electron source is known as the cathode, i.e. "cathode ray tube" and that electrons flow toward the anode.

Is my application of these terms backward in one of the examples?
Do the terms anode and cathode fail to uniformly distinguish electron flow?
Do I misunderstand the function of a vacuum tube?


texts:
I am trying to get a toggleable 2.0 to 2.6 ish voltage reference that can supply up to 45 mA.
I simulated the below circuit and found this to be acceptable. However upon building the circuit, I found my Vout voltage to be much higher, around 3.2V. The voltage drops slightly to 3.0V depending on the load (used 100 ohms to test).
So I think the Zener isn't operating correctly.
However, when measuring the voltage across the 50 ohm resistor (5.5V-3.2V)/50ohm = 46mA, I found that the Zener should be on! This Zener diode only needs like 5 mA to operate correctly. So what gives? Is the knee of this zener just really bad? What should I do to ensure the voltage never goes above 2.6V?
The PNP is toggled with a GPIO pin from an MCU.


texts: Finding the SOP expression for the XOR gate and the circuit for it

texts:
Would the sum of products expression look like so:
\$\overline{A}\cdot B+A\cdot\overline{B}=Z\$ ? And the corresponding circuit should look like so?

Sorry for the bad drawing. I'm just wondering if this is how this concept works, but surprisingly this is not in any obvious google results.

Thanks for any help!


texts:
Background:
Despite having a degree in Computer Engineering, working for 2 years as a vb.net developer, and someone that enjoys messing around with electronics. I've narrowed my buying options down to the PICKIT 3 or the ICD 3. Cost differential aside, I'd like to get something that I can get started with quickly, and will 'grow' with me as a PIC developer. As such, I'm heavily leaning towards the ICD 3. I'd rather invest in something good up front, then only wish I bought the better thing later. I've fried a power supply to my computer trying to build something before, so the option to replace the ICD 3 is lucrative to me.

Question:
Is it fairly common to fry a programmer during the learning process of PIC programming development? Worded differently, and based on your experience, would you agree that the option to replace the programmer outright is valuable?


texts:
I have this existing LED circuit with 2 LED strips with built in resisitors and 1 switch. Normally 1 LED strip is always on and when the switch is closed the other LED strip also turns on. Power Source is a Sealed Lead Acid battery 6Ah and the switch is a regular rocker switch.

I want to modify this circuit so that an MCU can control the LED strip which was wired to be always on in the existing circuit. So I have made this new circuit diagram which I want to verify is correct or not. In the new circuit diagram (+) power from the closed switch goes to a tiny buck converter which steps it down to 5V for the MCU (ATTiny13a). (- ground) of the second LED strip goes to the drain of an N channel Logic level MOSFET which has it's gate connected to the digital out pin of the MCU. The function of the MCU is to make the LED strip blink every other time the switch is closed. The programming for the MCU will make use of the EEPROM to achieve this so that it knows (remembers) when the switch was closed last time.

In short, the intended function of this circuit goes like this

Switch Open - Both LED strips OFF
Switch Closed - First LED strip ON, Second LED strip OFF
Switch Open - Both LED strips OFF
Switch Closed - First LED strip ON, Second LED strip blinking

... and this function repeats

Note: I want the second LED strip to stay OFF even if the MCU isn't powered.

So I wanted to know if my circuit was correct or is there something wrong? like the way MOSFET is connected to the MCU?. Also is it possible for me to switch the (+) of the second LED strip with the MOSFET instead of switching it's (-) ground?


texts: When exactly was the RS-232 standard issued?

texts:
This year is 50th anniversary of RS-232 standard. Despite its age it is still used nowadays, and I work in company that has to deal with it.

So we have a half-serious idea to celebrate the exact day the standard was issued. Does anyone knows that date? Maybe someone has printed copy to look into?

Though this questions relates more to history than to electrical engineering, I think that this site is the best place to find people who might have an answer. I've asked this question on Superuser, it was closed as off-topic, but I was advised to ask here.


texts:
How do I go about identifying an LCD display module so I can get a data sheet?

16 Pins to one side in 2 rows of 8.

printed on PCB: hy-211
printed on PCB: v0022201 rev.b

printed on a sticker on side: 2220stldygbn-0   255

No other identifying marks on PCB


texts: solder pins for stripboard to breadboard

texts:
This might be a really daft question but...

My breadboard accepts 0.6-0.8 wire sizes. I have a load (about 50) SMD chips soldered to breakout boards, the boards have 1mm holes for pins, same as standard stripboard. I want to test all of these chips on a breadboard circuit- but the solder pins are 1mm and don't fit into the breadboard! Any such thing as a pin that is 1mm at one end, but thinner at the other? What would such a pin be called? Is my breadboard just abnormal? Any better ideas on how to test all these breakout boards?

Bonus points if the parts/pins are sourcable in the UK too!


texts: Questions about voltage drop at the transformer secondary and primary due to loading

texts:
Below there is an impedance matching aimed step-down transformer circuit where the primary to secondary turn ratio N1/N2=10. To actualize such turn ratio and voltage ratio, I set the inductor ratio L1/L2=100. I also set the magnetic coupling coefficient K1=1 to neglect any magnetic leakage. And I also set inductors' series or parallel resistances and capacitances to zero. But I guess this still does not represent an ideal transformer.

I have come to this conclusion because of the following observation. When the secondary is open V1/V2=10 where V1 and V2 are rms values of the primary and the secondary windings. This is expected since we set the ratio to 10. Below circuit and the plots shows this:

But when the secondary is loaded with 8 Ohm load as in the below circuit, both V2 and V1 starts decreasing as we increase the loading by decreasing R2 as shown in below plots:

And the the winding currents does not have ratio of 10:

My questions are:

Why does the secondary voltage decrease when loaded? And most importantly why does the primary change at all? I think I have some fundamental wrong understanding of a transformer. I thought primary's action is independent from secondary. So I thought the process is unidirectional like in an amplifier i.e. output port is dependent on the input port but not the other way around. How to explain this?
When the secondary is loaded the voltage decreases but voltage ratio is still 10 but why does the current ratio is very different and varies with loading? Isn't  V1/V2 = I2/I1 always?


texts:
I am designing a simple 16 bit adder circuit in Digilent's Xilinx Spartan 6 FPGA. The Verilog design accepts two 16 bit inputs A and B and returns the 16 bit sum C = A+B. I am ignoring carry in and carry out.

I want to send A and B from PC to FPGA using serial port as well send the sum C from FPGA to PC using serial port. I am not sure how to do this. I have googled but could not find something simple. Can i send A and B as decimals like A = 5, B = 3? or do i have to send it as ASCII? How do i distinguish  A from B if A = 255 and B = 512 (i.e., both A and B have multiple digits). How does FPGA deal with ASCII.

Some pointers or explanations will be really appreciated


texts: How can I make a test bench for an electric motor?

texts: I'm in college and we are designing a plane for SAE Aero Design, we are trying to come up with a design for a litle test bench for our motor any idea how can we do it, a DIY way, also do you guys have any advice for us?


texts: Need help modifying a motion detector circuit

texts:
I'm working with my son on a 4-H project, and we have great ambitions, but very limited knowledge.

We're looking to use a motion detector to switch off the current to electromagnets that will hold the doggie door closed.

We found a Motion Triggered Room Light Kit at Jameco, and it looks like it would do the trick for us except that it's designed to turn power on when motion is detected - we need it to cut the power to the magnets so the door will swing.

The other thing we'd like to be able to do is modify it to use 2 motion detectors instead of one - one on each side of the door so it unlocks no matter which way the dog is coming through.

We'd also like to eliminate the light sensor portion, as we want it to work day and night. It looks like replacing the CDS photo resistor with a regular resister of the appropriate resistance (it looks like 100KΩ should do the trick, but I'm not 100% sure). We can simply leave the light sensor inside the box so it always thinks it's night if need be.

Here is the schematic provided with the kit:

Sorry it's not particularly good quality, I simply pulled the image from the PDF of the instructions I downloaded from Jameco

We can do the soldering and follow the very detailed instructions in the kit, but neither of us have enough electronics knowledge to be able to modify the circuit to do what we need.


texts: Microcontroller circuit. How many capacitors needed for Vdd?

texts:
I am developing a circuit for a dsPIC30fxxxx microcontroller. In the documents I found a picture that depicts the Vdd circuits, see attachment.
What does the picture say?
Do I need 3 capacitors for each Vdd?

B


texts:
I have a question regarding the LM317 and PWM. My circuit receives +12v and has three grounds (R,G,B) that are PWM. I need to drop the voltage down to 3.2 volts from the 12 volt source.

NOTE: I know this could be done with resistors, but that is not what I want to do. Also, I cannot change the 12 volt source or the grounds.

Here is my circuit:

I am using a LM317 to take the 12 volt source and dropping it down to 3.2 volts. The issue I am having is when I run the LM317 to ground after the R1 resistor. Since R, G, and B are PWM grounds, will that impede the LM317 and not result in a nice 3.2 volts?


texts: Power factor correction in a simple phasor circuit

texts:
I've been having a bit of trouble with a relatively simple power factor correction problem involving a simple circuit in the frequency domain (\$f=50\,\text{Hz},\omega=2\pi f=100\pi\,\text{rad/s}\$).

From what I can tell, my first step is to determine the complex power \$S=V_{eff}I_{eff}^*=\frac{V_{eff}V_{eff}^*}{Z_{eff}^*}=\frac{|V_{eff}|^2}{Z_{eff}^*}\$ consumed by the circuit in its current state (without the corrective capacitor), in which case I figured the total impedance should be \$Z=-j10\,\Omega+\dfrac1{\dfrac1{20\,\Omega}+\dfrac1{j20\,\Omega+10\,\Omega}}\approx11.435\angle{-19.653^\circ}\,\Omega\$.

However, this strikes me as quite odd; \$\arg S=\arg Z<0\$ suggests that the power is lagging and therefore (intuitively) the power factor cannot be 'corrected' with the use of another capacitor (negative reactance), requiring instead an inductor (positive reactance).

In fact, when trying to solve this problem, I found two results -- both giving positive reactances \$X_C=-j\frac1{\omega C}\$ and thus 'negative' capacitances. This is nonsensical, no? Have I computed the total impedance incorrectly?

Thanks.


texts: Thevenin and Norton circuit analysis example

texts:
I have trouble solving the following problem, I have to find the Thevenin and Norton equivalent at the head of the R5 resistor:

simulate this circuit – Schematic created using CircuitLab

I have calculated successfully the equivalent resistance, I am having trouble finding Vth, I replaced R5 with an open circuit like this:

simulate this circuit

But I don't get the expected result, I realize that this problem isn't necessarily difficult, but I find that there is something I am missing while trying to solve it and I would appreciate some help, thank you !


texts:
I am using a 3v3 logic level (VCC in schematic) to switch low-current 12v power for a remote sensor (SPWR). The switch is to power down the sensor when not in use to save power. Even with the sensor removed, so that SPWR is open circuit, the MOSFET does magic smoke and dies. I can't fathom what's going on here.
The MOSFET is "P Trench 30V 4A 1.3V @ 250uA 44 m? @ 4.3A,10V SOT-23-3L": https://datasheet.lcsc.com/szlcsc/Alpha-Omega-Semicon-AOS-AO3401A_C15127.pdf
The NPN transistor is an S8050: https://datasheet.lcsc.com/szlcsc/Changjiang-Electronics-Tech-CJ-S8050_C2146.pdf


texts: Once a week pulse out of small circuit for slow clock?

texts:
I have a clock (a regular quartz clock), that I want to go very slowly. I want it to tick 60 times a year.

I disconnected the internal chip and hooked up an arduino to do the counting, and every 525948.76 seconds it tells the clock to tick. This works fine, but using an arduino is overkill.

How cheap and simple could I make this "pulse every 525948.76 seconds"-device that would replace the arduino? It would not need to be as precise a timekeeper as an arduino.

(this person did the same thing and explained how to
http://www.cibomahto.com/2008/03/controlling-a-clock-with-an-arduino/)


texts:
I have an EE background, but am new to metering hardware.  Looking at metering equipment for high voltage measurements (up to 6.6 kV), it seems most only go up to 480 V, even when classified as industrial.  Some are marked as having "Transformer input" or "resistive divider input" for voltage.  Couldn't any meter have input come from a PT?  Are there some models that are more or less accurate when measuring through PTs?  Am I missing something obvious about how to measure high voltage signals?

Thanks


texts: How to solve via on pad without plugging?

texts:
There are some vias on pad in my design. I've read some articles and know that these vias should be plugged to avoid solder wicking. However, the board house told me that they can't provide a plugging service. Besides, it's impossible for me to move all the vias out of the pads because of the narrow space.

Can someone help me to find another solution to handle these vias on pad properly?


texts: Voltage in a circuit at a particular point

texts: Can anyone help me in understanding how to simplify this circuit and get the voltage at point V? The negative terminal and 1 ohm resistor have a ground in between.


texts: One wire (+GND) serial communication. How to have a correct coupling?

texts:
I'm a firmware developer more than a hardware designer. I've a doubt about an idea of mine.

I want to obtain serial communication between eight ATtiny85 (slaves) and an ATmega168 (master - It might be also an ATtiny85, but for this question is the same) using only one wire (plus GND).

I'm writting my protocol and it  begins to run. I've used the INT0 pin (PB2) of the ATtiny85 and the INT0 (PD2) of the ATmega168; these pins act as digital output when transmitting and, after transmission or as normal behaviour, become/are digital input to receive.

All the MCUs have the same power source, then if two MCUs transmit simultaneously there will be line conflicts and short circuits (if one transmits 1 and an other transmits 0). I want to avoid short circuits!

Is it the right way to use resistors connected with each single pin
limiting the current?
If I use 9 resistors on the line, one for each pin, do the signal
will have stronger attenuation?

At now I will avoid to use active chips other than the MCUs to manage the communications!

The MCUs are each one on a separated circuit, not on the same card, as it may seem in the following picture.

I apologize for the bad pattern, but I have not designed it yet. I have only a small breadboard with just two MCUs now.

simulate this circuit – Schematic created using CircuitLab


texts: Using single-supply OpAmps with a bipolar-supply OpAmps in the same circuit

texts:
I have a prototype circuit that is based around some arbitrary bipolar-supply OpAmp.

It uses "virtual ground" voltage divider so that it can be powered from a 9V battery (hence the "-" of the battery goes to -4.5V rail, the "+" goes to +4.5V rail and the middle point is the "virtual ground").

The requirements evolved such that now I need to add a high-precision OpAmp to one of the stages. However the chip that I will be using is a single-supply chip that would be connected to the "virtual ground" and the +4.5V rail.

Is there any general reason that I should expect degradation in signal quality, now that one of the stages uses the -4.5V rail as negative supply and the new stage uses some internal-to-the-chip negative rail that might be slightly different?

The various datasheets and implementation notes that I have found do not discuss anything of the type.

Here is the single supply opamp datasheet: http://pdf1.alldatasheet.com/datasheet-pdf/view/28867/TI/TLC277.html


texts: How to take bank configurations in NAND flash chips into account?

texts:
8-bit bus, 8 GB NAND flash chips come in a variety of bank configurations:

1 x 8 GB  (e.g. Toshiba 04914-008G)
2 x 4 GB  (e.g. Micron 29F64G08AFAAA)
4 x 2 GB  (e.g. Toshiba HVPG3P3)

What are the differences in terms of interfacing (electrically or logically) and addressing? Does it make any difference?


texts: How to connect 2mm surface mount component to 2.54mm breadboard

texts:
I have an RF link module with surface mount connectors 2mm apart. This is the datasheet.

How would I connect this to a breadboard with 2.54mm spacing?


texts: Using Electronic Components To Make A Chain Reaction

texts:
I've been tasked with creating a Rube Goldberg machine that employs mechanical, chemical, and electric components as a school project. I've got ideas ready for the two former topics, but I'm stuck on what to make of the electrical category. The rules of the project state that I cannot use any computers or integrated circuits, but I'd still like to have something creative and effective in the machine. I am allowed to use batteries (up to 10 V) and battery-operated motors.

The purpose of the machine is to move golf balls from their original positions to activate the next portion of the reaction, so lateral movement, lifting, and dropping are all valid options. My main concern is that I'll end up using just switches activated by the golf balls and not anything more complex or varied. Have any ideas on what I could implement into the box?


texts: Is there a standard symbol for a pressure sensor?

texts:
I am using Eagle to design a PCB that includes an analog pressure sensor. However, I can't seem to find if there is any standard symbol for the device. There isn't anything on the datasheet. I began to browse the web without much luck. Some block diagrams represented them as a simple circle with an "X" inside. Some schematics showed them as a circle or a circle with an arrow inside.

I also looked to see if there was a symbol for a generic transducer. Results included what I thought was the symbol for a piezo oscillator, as well as more circles with symbols inside.

Is there a standard symbol? If not, what is my best bet? Should I draw a circle with an arrow or letter "P" or something? Would it be better off to draw a block and label the appropriate pins, like some ICs?


texts: How can I build a 12V to 24V DC-DC Converter with up to 3A of Output current to power up a motor

texts:
I've built a 12V to 300V boost covnerter using a MAX1771, but now required one which can handle up to 3A with a 24V output. Should I attempt this task with the same chip or could someone point me in the right way to solve this problem?

EDIT: MAX1771 can only handle up to 24W of output power, seems like I'll have to find an alternate.


texts: Does a solid-state DIN relay typically need a flyback diode when switching an inductive load?

texts:
I'm using this Phoenix Contact DIN rail relay, DigiKey part 277-17665-ND (data sheet). I thought it would be prudent to add a flyback diode, but looking at the data sheet, it vaguely suggests it already has protection.
In the section “Input Data”, there’s a line “Type of protection” with value “Free-wheeling diode.” In the section “Output Data,” “Type of protection” says “Reverse polarity protection” and “Surge protection.” Later it says the rated surge voltage is 4 kV.
I don’t know much about industrial controls, but it would be convenient if they could handle inductive kickback without external protection, so I wonder if they don’t.
My inductive load is a motion brake (data sheet) labeled 24 V, 0.41 A, 9.8 W (and that was borne out in measurement on the bench; the data sheet is incorrect).
Will my relay be okay without additional protection?


texts: Garbage value written in .csv file by ADC


texts: Is it possible to power an AC-to-DC switching adapter with a DC input?

texts:
Typical "wall-wart" switching power adapters are often rated for ~110-240V 50-60Hz AC input and output low-voltage DC. For this question let's assume the output voltage is 5V DC.
Internally, the adapters pass the AC input through a rectifier to produce pseudo-DC, and ripple is reduced with one or more reservoir capacitors. The now-smoothed DC is then sent through other electronics (e.g. a transformer, a switching element, regulator, etc.) to produce the DC output voltage.
Can these adapters also be powered by a DC input?
My naive assumption is "yes", since the AC input is rectified to pseudo-DC and the internal components operate on the pseudo-DC. This seems to be supported by this page, which states in part

The reason for the lower frequency limit being imposed is owing to the smoothing capacitor not being able to hold enough charge between cycles. The lower the frequency the higher the ripple, the higher the ripple the hotter the cap will run. The upper limit is due to the above mentioned input filters starting to filter out the mains frequency and, as they would now be absorbing energy, would run warm.
Powering a SMPS from DC eliminates both the above problems. The capacitor is no longer required to hold a charge between cycles as the DC will maintain a constant input voltage and the filters would merely prevent any unwanted spurious generated by the SMPS from reaching the incoming supply.
The only concerns when operating a SMPS from DC is the incoming voltage range that ensures correct operation. The lower DC limit is the lower AC limit multiplied by 1.414 e.g. 85VAC would mean 120VDC lower limit. The upper limit of 240VAC equates to 340VDC, 265VAC being 375VDC, levels not usually found.

Does this seem reasonable?
Are there any risks, either to a person or to the adapter itself, that might arise if testing such a setup (other than the typical risks of working with mains-level voltages)? While one risks failure by using a higher-than-rated input voltage, should one expect issues if using a lower-than-expected voltage? For example, while connecting an adapter to a 12V DC input might cause it to not work, is it possible to damage the adapter?


texts: i have a circuit in which some components need 5V and some need 3V.

texts: should i get 3V battery and go for a buck boost or 7.4V battery and go for a voltage regulator? which is easier and better to use?


texts: Troubles using a Low-Dropout Linear Regulator

texts:
I've designed a board, that includes a charging part :

the problem that I have is in the LMS8117A-3.3:

here I can measure 5V on Pin1, but nothing on pin2, I was expecting 3.3V :
I've check the board and no I don't have any bypass, to test the board, I've put a 3.3V voltage at "target voltage pin" and the board works fine! So my question is how may solve this and what am I missing!
This the layout part!

and here a link to the datasheet


texts: What does this logic/circuit symbol mean

texts:
While browsing through the datasheet of an ATMega324p description of a pin I noticed this symbol which looks like four diodes/triangles pointing at each other.

So my question is what is it actually?


texts: How do I answer to a question asking "Is the purpose of the trigger system to sincronize the signal acquisition with the input"?"

texts: I'm aware you can get triggers from other sources and that in general the trigger syncronizes the acquisition with a trigger event. But as for its purpose, is it always to sync the acquisition with the input?


texts:
I need to buy a 9 pole mini din plug (male) to create a ps2 -> quadrature mouse adapter but I'm a little concerned the socket I'm connecting to is non-standard:

[
The reason I think this is the top 3 pins are not evenly distributed and the data sheets I look at for ordering online have them evenly distributed.
So my questions are:

Is this socket standard?
Are the datasheets wrong?
Could I buy a 10 pin, and just pull one of the pins out of the plug?


texts: Inverting effect of resistance in an RC circuit

texts:
I have a question on basic electronics. I'm looking at a very simple CMOS RC Circuit around a Schmitt Inverter which creates square waves. Something like this.

simulate this circuit – Schematic created using CircuitLab

Now the frequency of the square waves is a function of the value 1/(R1*C1). Hence the frequency is inversely related to the value of the resistance. High resistance = lower frequency

Is there any configuration of such an RC circuit where the relation is direct instead of inverse? Higher resistance = higher frequency? I was thinking along the lines of having a second resistance and getting to the ration of R1/(R2*C), but I can't figure out the circuit.

My use case for this is when R1 is replaced with a LDR. LDRs increase in resistance when light level goes down, but I would like the square wave frequency to increase instead when the light level goes down.


texts: How to make electronic systems which work below −40°C (−40°F)?

texts:
I notice on a lot of electronic products that most of them work down to −40°C. Glaring example with Microchip microprocessors page: https://www.microchip.com/ParamChartSearch/chart.aspx?branchID=1012 (check last columns).
What I want
I would like this electronics to work down to −80°C (or ≈ −110°F)
What I cannot do
I cannot "heat" the case of my circuit or even the circuit itself.
Some examples

weather balloon (−56°C from 10km to 15km excluding extremes)
electronic thermometer for Pfizer vaccine freezer (−60°C to −80°C)
Perseverance rover (on average −65°C on Mars excluding extremes and excluding SuperCam)
rockets
military air planes
satellites
etc.

My case
Operate a fairly basic electronic system in a remote-controlled air balloon at very high altitude thanks to Dihydrogen or Helium. The circuit should work for about 7 hours.
So I have 3 questions:

Why "generally" −40°C? Why this particular value?
Why not −39°C, −41°C?

Can we add additional protection to withstand its low temperatures (until −80°C or ≈ −110°F)?
I sometimes see on certain circuits a thickness of silicone poured on the circuit. I understood that other alternatives exist such as urethane, varnish and acrylic. Does it help withstand the temperature? Let's assume we want to run a board in a −80°C freezer.

So how do space electronic systems work?
For instance, on Perseverance rover, SuperCam need to be heated to maintain a temperature above −40°C. However the remaining parts are not heated. So if it does work, how?

Warning
I think trying to found a specific "patch" to my case is not a good idea. The real answer could be very useful and would allow me to modulate my needs and truly understand how it could work.
The question is about TEMPERATURE. Please AVOID long developing on anything relating to:

electromagnetic compatibility (CEM)
pressure
rapid temperature change
UV / infrared / light destabilising electronic circuits
efficiency

We just stay focused on the temperature. Can come into the line of sight:

humidity or condensation
ice formation


texts: matching network design for transceiver with differential outputs

texts:
I'm trying to learn about matching networks.  I have a 2.4GHz radio chip with differntial TXP/TXN outputs, and RXP/RXN input.  These both share the same single ended antenna.  I've been reading and I sort of understand how you would come up with a matching network from a single ended transmitter to a single ended antenna.

I don't really know where to start with two differential inputs.  I've seen it done with just passive LC circuits but I can't say I can follow the circuit.  I assume you need

a way to connect the RX and TX
then a balun to go from diff to single ended
maybe the inverse of that for the receiver
an impedance matching portion for the antenna
some EMI filters?
DC blocking?

Where do I start with something like this?


texts:
I have difficulty understanding how the delay (mainly inertial delay: AFTER) mechanism works in VHDL.
I'll start with this:

target <= waveform AFTER 3 NS;

As long as waveform is a pulse longer than 3ns it only gets delayed by 3ns, else nothing appears on target. But that's just the result of how VHDL interprets the above signal assignment. I want to know what exactly happens there! For example what happens if we have a conditional assignment defining waveform itself, like this:

waveform <= '1' AFTER 2 NS WHEN (waveform = '0' AND NOW < 10 NS)
                           ELSE '0' AFTER 5 NS;

(I got a bit carried away writing the condition!), What I mean is which time and value for waveform are taken into account when evaluating the condition to assign waveform to target. Or is waveform simply evaluated (drawn) to obtain an actual WAVEFORM and then applied to target as I said above (shorter than 3ns gets thrown away, otherwise just shifts 3ns); [I know its obviously not the second way, just wanted to make my point.]


texts: Heat sink for the L298 stepper driver IC

texts:
I am coming today to seek help from you for sizing a heat sink for the L298N IC.
This Ic will be used to drive a 2A/phase stepper driver, supplied with a 12Vdc signal, and 5Vdc for the logical part.
The stepper motor will be driven in a way that only one phase will be energized at once. Which should mean that it will consume a maximum of 2A at once.
If I understood well, first thing I have to do is to calculate the maximum power that my Ic will consume.
Could you verify my calculations, and if they are wrong, explain me why? Thanks a lot
Power supply voltage = 12V, Quiescent power supply = 50mA    -> P = 600mW
Logic supply voltage = 5V, Quiescent logic supply = 25mA     -> P = 120mW
Input High voltage = 5V, High voltage input current = 100uA  -> P = 0,5mW
Enable high voltage = 5V, High voltage enable current = 0,1uA -> P = 0,5mW
Source saturation voltage = 2V for input current = 2A         -> P = 4000mW
That would give us a maximum total power of 4721mW = 4,721W...does that make sens?
Those are the electrical characteristics describing the L298N found in the datasheet :

Thanks in advance !


texts: Bypass SuperSpeed USB3.1 lines around USB2.0 Hub

texts: I found this document online, which shows an interesting USB routing topology that I have not seen before.  The 4x superspeed lines go straight from the USB3 connector to the SuperSpeed IC, but the USB2.0 lines go off to a USB2.0 hub, where one of the down stream ports connects back up to the SuperSpeed IC.  I can't find any other examples of this online... is this allowed?  I would have probably just designed in a USB3.1 SuperSpeed hub, and not split the signal lines off.


texts: Which transistor and resistor(s) do I need to hook up the FSA-410BT smoke alarm to Raspberry Pi's gpio?

texts:
The documentation for the smoke alarm: http://cms.dsc.com/download.php?t=1&id=16756

When the alarm is going off, this device draws 25mA (max) and idles at 20µA. It's 12v too, and I'm sure that complicates it.

I would like for the non-alarm state to be closed, and the alarm state to be open.

I know there are many transistor types, but I'm completely ignorant of the differences in any meaningful ways (some allow higher currents or lower currents, some higher voltages or lower... not very useful).

Is this even possible in a single device, considering that the alarm is 12v while the gpio is 3.3v?

I intend for the cable to be between 12ft and 25ft. I have not selected a particular kind, and if this affects the answer I can choose whatever is recommended (shielded, gauge, solid/stranded). If this is sensitive to the exact length of the cable, I can get the measuring tape out and provide something more specific (to within +/- 8 inches or so) in a few hours.

This model does not include the optional (LED) terminals.


texts:
The company I work for uses conductive point-level water sensors to determine water level in a small tank. The manufacturer of these sensors has proven to have very unreliable quality control and ~30% of the sensors we buy for them fail in the field. This is very bad for us because our machines are usually in remote locations  which makes it expensive for companies to send techs to service them.

We have looked at the following alternatives

Capacitive sensors

These sensors come with a screw on the back to set the sensing distance. We have tried to determine a standard setting from the factory, but some of the units that we have received with the standard setting have needed adjustment. It seems that the sensors are dependent on temperature/humidity etc. This, in my mind, makes these sensors a bad solution

Optical

These sensors work great until a film develops on the surface

We are very restricted in our mounting options as well. The sensors mount to a 1"ID ,1.25" OD sight-tube connected in parallel with the tank. There are 3 M12x1 tapped holes in the side of the sight-tube that the sensors screw into. One sensor at the bottom, one sensor in the middle and one at the top.

If these restrictions weren't in place, I would go with float switches, but since they are It seems to me that the best solution is a custom conductive sensor.

My idea is to first find some sort of 2 pin electrode that will screw into the M12X1 tapped hole. Then develop a circuit to connect to one of the electrodes(555 timer generating a sinusoid) and a detector on the other electrode that detects when the electrodes are shorted by the water.

The trouble I am running into is finding suitable electrodes. Does anyone have any suggestions for what I might be able to use, or any other potential solution? I have attached a picture of our current sight-tube and the sensor we use currently.

Our current sensor has the signal generator/detector inside of it, and because of the constant issues we have had with this company, my manager does not want to entertain the idea of having them make us electrodes based on their current design.

The interface that the sensor goes into is a 1.25" housing with 0.25" walls. The screw thread that it must fit into is M12x1

There is an opportunity to change the thread size/hole size if an off the shelf solution is available.


texts:
Are dielectric losses the same for two different 50ohm structures that are built in the same dielectric medium?

Eg. Two 50ohm Stripline traces in FR4 where one is very skinny with close GND planes, and another where traces are very wide with far GND plane separation.


texts:
If I have the following circuit and I want to reconstruct using only NAND gates is my approach correct?
Initial:

simulate this circuit – Schematic created using CircuitLab

Solution:

simulate this circuit

I am getting conflicting information online so I wanted to make sure I am understanding this correctly. Are my conversions correct? A clear explanation of how to go about bubble pushing would be also very helpful.


texts: Finding the operating point of a transistor circuit

texts:
I want to find the operating point of this circuit:

where we have a npn-Transistor and \$R_V = 47k\Omega\$, \$R_C = 1k\Omega\$, \$R_E = 4,7k\Omega\$, \$\beta = 100 \$,
\$+U_B = 10V\$ and \$-U_B = -10V\$.

My problem is, that I don't even know what the operating point really is.
In the exercise it says, that the operating point is the pair \$U_{CEA}\$,  and \$I_{CA}\$. But there is no letter A in the circuit shown.

So what is the operating point in general, and how would I go about finding it here?


texts:
I'm designing a very simple microcontroller breakout board. I wonder how can I protect microcontroller output pins against accidentally connecting another signal to one of them and burning the pin's output driver (because it's an output not input) ? Would a small (say 10 ohm) resistor in series to the pin be enough to protect it ?

EDIT: For example mistakenly switching UART RX and TX line.


texts:
Good Morning,

I am a scripting programmer (PHP) and do a lot of backend development with web servers.  I am very interested in learning VHDL, but the tutorials I have tried seem very antiquated and difficult to follow without some previous coding experience directly in that language.  I am considering buying a Xilinx FPGA, but would like to learn more before I make an out-of-pocket purchase.

I especially interested in online or downloadable testing environments where I can prove out a theory before I move forward.

Any advise here is appreciated!


texts:
I seem to be having a weird issue regarding cbi/sbi instructions on Atmega8-16AU.

I have it connected to an external 16Mhz crystal.

I am able to verify that it is running at 16Mhz by using _delay_ms(1000) and checking with a logic analyzer that indeed a delay of 1 second is produced during toggling of an output pin.

However when I call the following the assembly function:

asm_toggle:
    sbi PORTC,4
    cbi PORTC,4
ret

I would expect PC4 to be HIGH for 2 clock cycles ((1/16M)*2) or 0.125us. However when I check using a logic analyzer, the pin is actually HIGH for 1.5us! That's almost 24 cycles.

I understand that some cycles would be used for jumping and returning to the function from the main routine but that should not affect the actual HIGH time of pin PC4.

Can someone explain whats going on here. I have a feeling that I'm missing something very basic here.

There are no interrupts running and my fuse settings are

LFuse : 0xFF
HFuse : 0xC9


texts:
How can I draw the timing diagram for the circuit below? What are the steps?

I can't understand even how to read it. What do I do with the numbers below each logical port, eg: 5ns , 10ns etc)?


texts:
I'm trying to understand how this AD8402 digital potentiometer works, I need it to be decoupled from the circuit it's driving, that is Vdd, GND and all logic inputs not connected in any way to A, B and W pins.

According to the figure 45 (page 20) of the datasheet I think I can safely connect a 5V power supply to the IC power pins and connect a completely different system (also 5V) on the A, B and W pins.

On page 11 however it seems that VA, VB and VW must be between VDD and GND...

Also on page 24:

  Certain boundary conditions must be satisfied for proper
  AD8400/AD8402/AD8403 operation. First, all analog signals must remain
  within the GND to VDD range used to operate the  single-supply
  AD8400/AD8402/AD8403.

My question is: can I connect the VDD and GND of my AD8402 to my 5V supply and regulate a potentiometer input on another device that supplies its own 5V and GND to the A and B pins, but without the GND of the AD8402 and the device being connected?


texts: Beta Multiplier Reference: What is going on with the current output?

texts:
I have been working on a beta multiplier reference circuit using a 0.35um CMOS process. The circuit was previously designed and tested for a 0.7um process, but otherwise there have been no changes to the implementation. The circuit has no input, only a nominal supply voltage VDD of 3.3V and an output current I which is the drain current of transistor M1 (Fig. 1).

The circuit was simulated with a DC sweep of supply voltage VDD. For a supply-independent reference, what's expected is a current response with a generally flat profile from 3-10V (Fig. 2). Instead, the simulation shows a sudden increase of I at VDD ~5V (Fig. 3).

Any thoughts on what exactly is the cause of this current behaviour? I have tried scaling the linewidth of devices as well as fiddled with W/L ratios, but the "breakdown" at ~5V still remains, so I suspect the issue might be CMOS process-related.

Device dimensions, W/L (um/um):

M1 : 160/40

M2 : 40/40

M3 & M4 : 2/10


texts: Resistor value calculation for optocoupler input

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I am working on an optocoupler (LTV-845) circuit.
Below is my working circuit:

Forward current flowing to opto input would be
(Vcc-Vf(LED)) / Rf = (24V-2.1V)/470 = 0.046A.
Is my understanding correct?
Also need to understand whether LTV-845 is capable of handling 0.046A, as the forward current is 50mA maximum and collector current is 80mA.
Need clarification.

This would be my circuit:

What would be the current flowing to the load connected to pin 3 with RL=1K?


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I have an LED (don't know the part number unfortunately) that lights up red when its anode is tied to Vcc and its cathode to Gnd, and when the polarity is reversed, it lights up green (opposed to some common cathode LEDs that have multiple anodes, this one has only 2 "legs")
The LED has a forward voltage of 1.8V, so I calculated a current limiting resistance of 330 ohm (about 10mA)
I'd like to make a transistor equivalent of this circuit:

simulate this circuit – Schematic created using CircuitLab
I came up with this circuit:

simulate this circuit
When A is tied to Gnd, the LED lights up green (as expected), but when I pull A high (at Vcc) the LED is not lit.
I measured the emitter voltage at Q1, and it is about 3.3V. Same goes for Q2's emitter, but in both cases.
I don't quite understand why the emitter voltage doesn't drop to 0V (I used this question's answer as inspiration). Am I missing some extra resistor somewhere? (or is this not the recommended way to switch polarities?)
Thanks in advance


texts: What's the relationship between capacitor and resistance in a fading LED circuit with a 555 timer?

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I followed the instructions in this video to make a fading LED circuit with a 555 timer:

https://www.youtube.com/watch?v=qLAi7hkDuYw

...apparently loosely following the schematics here:

Note that the guy in the video uses different values for both resistors, the capacitor and the voltage source, and only one LED. And so do I. I use a 6V voltage (4xAA), a 130Ω resistor in series with two 3,4V LEDs in parallel, as the "high" resistor I use a potensiometer, and I use a 470µF capacitor. All is good and the circuit appears to work as it should.

1) Now, what I don't understand is the relationship between the capacitor and the high resistor (potensiometer). In the video instructions the guy said to use a 1000µF capacitor, which I tried. The comments below the video said a much smaller capacitor was all that was needed. I found that there seemed to be a linear-ish relationship between the capacitor and resistance. I could choose different values of capacitors, adjust the potensiometer, and the circuit behaved the same. Can someone explain this to me, and whether I'm tinkering with this in the right way?

2) Is the 130Ω resistor in series with the two LEDs (in parallel) an adequate value?

Thanks for your help.


texts: One shot pulse generator Low->High->Low even if button is still pressed?

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I am trying to use a 555 IC to create a low-high-low pulse that will trigger only once and still go low even if the button continues to be pressed. This is the circuit I have now but the pulse stays high if I continue pressing the button:

Edit: Wrong circuit diagram


texts: Creating a Delay Locked Loop (DLL) on an FPGA

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I currently have a delay line using a series of flip-flops and buffers which precisely measures the time between rising edges of a start and stop signal. I would like to implement a delay locked loop (DLL) on my FPGA to help reduce error accumulation between flip-flops.
Has anyone designed a DLL on an FPGA before and could provide some useful resources or advice? Most of the information I have found online uses FPGA's with existing DLLs or ASIC designs that use custom DLLs.
Cheers
Here is my delay line architecture:


texts: Wiring a switch to a new power supply for a 12v lamp

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I am trying to fix a sign that wouldn't light up anymore and I got confused when it came to installing the actual switch. It does work now but with the "fix" (replaced electronics of the sign with a new power supply) I have no idea where the switch goes.
So originally it had a lightbar in the back of the housing, with two wires +/- going to a board. That board also had 4 wires going to a switch and two more wires +/- that went out to the wall plug.
I disconnected the lightbar from the board and hooked it to a generic 12V power supply that's just a wall plug with 12V/1A output where I cut the dc plug off so I have the + and - wires. Now the light works when it's directly on the power supply but where does the switch go? The switch I have has 4 pins, but don't I only need to switch the one "+" wire coming from the power supply? I don't understand how that switch would be hooked up. I also don't know if I can just put the switch between the power supply and the light or if I need one between the power supply and the wall power socket.
Is this even possible with that switch or do I have to get a new one? Maybe that switch only works with that board because it did have 4 wires. I don't get what it had 4 wires for when it still works now with 2, do I need to split both to get 4 for the switch? If yes, wouldn't I need to split the wires on the lightbar as well?
I know I can give that up and plug the new power supply into a power strip that has a switch and then use that to turn power on/off for everything but that would look awful and the idea was to keep as much of the original installation as possible. I also want to understand this more so I explained as good as I can, I'm sorry if the question is stupid.
I have a photo of that switch. Please someone tell me how or if it can be wired or if I'm wrong and what else I should buy instead??


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I am trying to "light" all the net labels that are connected together , to see if everything is right.

So for example if one pin of a resistor called "R_A"  and another pin on some other chip called "R_A" , i would like to push something in Eagle to see both of them(and all other labels with the same name) in some bold color/light .

How would you do that in Eagle ?

Thanks a lot .


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The figure below is the schematic of the circuit,

I have to admit that this is a homework question which I have stuck for a while.

I try to use Wheatstone Bridge theory, but here in this question I couldn't find such a loop which  satisfies  that theory.
Even I couldn't see a conventional path to solve the circuit. For me this is a mess. That's why I am asking this here.