texts: Combining hand-routing and auto-routing in Eagle; selective ripup in an Eagle ULP

texts:
In Eagle I often prefer to route some wires myself (power, xtal, UBS, etc), and leave the rest to the autorouter. When I am not pleased with the result I route some more myself, and let the autorouter have another try.

My problem is undoing the work of the autorouter, without undoing my own work. The basic way to do this is simply not saving the autoroutered version, and then loading the board again. But once I make the mistake of saving the autorouted version (and purging the backups) I still want to be able to go back to the pre-autorouted version.

One attempt to do this is to identify all autorouted wires in an ULP and create the command string to RIPUP these segments. I can arrange for the ULP to identify the autorouted wires, for instance by giving them a different width. But the RIPUP command seems to ripup the selected wire segment AND ADJACENT SEGMENTS. So far I have not found a command that rips just the selected wire segment.

So I guess I have two questions:
- How do you combine hand-routing and auto-routing in an iterative (trial-and-error) way?
- Is there a way (probably using ULP and commands) to ripup a subset of wire segments?

(update)
I tried the opposite approach: in an ULP, gather all wire segments I want to keep, do a full ripup, and then restore the wires segments (using the ROUTE command). No success, the segments must be in a specific order for the route commands (not the order in which the ULP finds them :( ), the via's must be made first, and some more problems.

GRRRR, there must be an easy way to do this, or am I overly optimistic?


texts:
This is the view of my circuit related to the question. My intention was the opAmp will adjust its output so that the voltage on the speaker will be equal to the input waveform at the noninverting terminal of the opAmp(V(out_adder)).

Here you can see that(see red arrows), the output of U5 opAmp and the power on the transistors change while time passes and stabilizes at some level. However, this is not desired. I like circuit as when it is in its initial situation.

Here you can see the very first results in a closer look.

Here you can see the final results in a closer look. The distortions on the output of U5 opAmp result in(I assume) distortions(please focus on the peaks, there is a little bit clipping at some points which alters speaker voltage from V(out_adder)) at my speaker(load) voltage.

Why does the output of U5 opAmp changes in that way? I assume the changes in the power consumption of the transistors are tied to this change.

Edited to up.


texts: What if a capacitor exposed to slightly higher voltage than rated?

texts:
I'm building my 5 V circuitry for my bike's dynamo rated 3 W 6 V.

Today I went for testing peak voltages without load and capacitors, just with diode bridge 4 x 1N5819.

Unfortunately my multimeter doesn't have peak function, so I made peak detector from LM324N:

Capacitor used: 100 nF ceramic. Meter leads were connected to Vout and GND pin of LM324N. Maximum readings were 24 V at maximum speed I could do.

I tested this peak detector on my ATX PSU (bridge rectifier omitted), I got:

real 5V -> Vout = 3.9 + 0.1V (Vdrop of 1N5819) = 4V, delta = 1V
real 11.1V -> Vout = 9.8 + 0.1V = 9.9V, delta = 1.2.

Considering that real peaks are higher then 24V, real peak I'd say +2V for rough estimation = 26V

Can those peaks be damaging for 25V electrolytic capacitor with no load?
And with load?
I personally think if there is a load, the cap cannot be fully flooded (charged), hence cannot be damaged that way. But I'm not sure.

UPDATE:
Just in case I'll use 24V transil


texts: Why does my power diode have 4 terminals?

texts: I am using a high voltage diode (APTDF400U120G) to freewheel an inductor in a switching circuit. It has four terminals, two for either side of the diode.  I cannot figure out why this is.  If I only connect to one input and one output terminal will the rating of the diode be lowered from the listed 400A? What is the purpose of four terminals?


texts: How to change polygon clearance in Altium

texts:
In Altium, when I draw a polygon, it automatically leaves a gap around copper of a different net. However,  my Vin net is high voltage, and needs to have a 1mm clearance. Therefore, If I draw a Vin polygon, it needs to leave a 1mm clearance between itself and other nets. And if I draw a polygon of another net over a Vin via, then, again, it needs to leave a 1mm clearance.

I have tried setting the design rules, but to no avail.

How do I get polygon to automatically leave 1mm clearance when one of the two nets is Vin?


texts:
From this Reference Design, I have the following inquiry:
Usually in three phase applications I see varistors connected between phase to phase, or between phase to ground. In the reference design, the common point of the varistors RV1...RV4 is not connected anywhere. I would expect it to be ground, but they intentionally left it floating. How are varistors protecting in this case?


texts: in order to understand bldc motors and their working principle, I read a lot on the web, and I see them like a tripolar steppers, am I right?

texts: I was told my previous questions were not well received by the community, it was never my intent to post a repeated question or a bad formulated one, and english is my second language, not my maternal one. so I humbly request any corrections from the community so I can continue asking, please.


texts: 4-20 mA sensor output to STM32 ADC input

texts:
I have a industrial sensor with 4-20mA output and I want to read that output from Stm32 ADC pin but I need suggestions to do that work in a nice way.
Can you guys suggest me the best way to do it? It is very important for me.
Thanks.


texts: PIC18F4550 : How to convert 16 bits integer to two 8 bits chars in C?

texts:
I'm blocked because of an issue that is causing a lot of time loss. I've created a function to get the LSB and another one to get the MSB.
char get_LSB (int n){

    unsigned char lsb = (unsigned)n & 0xFF; // mask the lower 8 bits
   return lsb;
}

char get_MSB (int n){
    unsigned char msb = ((unsigned)n >> 8 );// shift the higher 8 bits
   return msb;
}

It doesn't work as when I call the function get_LSB or get_MSB I get a result different from what I expected. Let's check the following example:
void main() {
              TRSISC = 0x00;
              PORTC = get_LSB(100);// function should return 100 but returns 68
              Delay_ms(5000);
              PORTC = get_MSB(360); // should return 1 but returns 0
}


texts: How to power a button's LED within a guitar?

texts:
I'm working on a guitar, and the plan is to use three latching push buttons so that each pickup can be turned on and off individually. I'm fairly confident that the following diagram should work for that (Feel free to correct me)

The buttons I want to use are these, which have a built-in LED when turns on when the button is pressed.

Which brings me to my question: Is there a way to power the LED? If I introduce a 9volt into the wiring, wouldn't that cause problems with the guitar's standard electronics?


texts: Why would the capacitance of a co-planar pcb capacitor not match changes in nearby dielectric constant?

texts:
Background

I have a piece of double sided PCB that I am plan to use a capacitor to measure soil moisture (somewhere between 133-170MHz).

I used the "two-pin method" of measuring small capacitance on the Arduino (calibrated against several values of ceramic capacitors between 2pF and 1nF).

Using the insulated board, I got the following results:

Air: 62pF
Hand grip: 26-27pF
Immersed 1/4 in water: 48pF
Immersed 1/2 in water: 60pF
Immersed 3/4 in water: 69pF
Immersed fully in water: 97pF

Questions

Firstly, why would the capacitance value initially decrease as the dielectric constant went from 1 (air) to >1 (my hand and partially submerged in water)?

Secondly, why would I only see such a small change when the board went from air (dielectric constant of 1) to fully immersed in water (dielectric constant of 80)? I accept that the leads from the boards will have some effect on the capacitance, but I doubt that they will have enough effect so as to swamp out the effect of water.


texts:
I drew an AND gate as follows which mimics this diagram:

(source)

I understand how current flows between A and B(when both inputs are logical 1) because there is difference of voltage, maybe 6V, and AFAIK A and B are possibly connected making a circular circuit(at least via earth).

But I don't understand how current can flow from some signal sources to two transistors to manipulate transistors. There seems no difference of voltage regarding i1 and i2. I want to know the entire circuit diagram including the signal sources.

PS. Are there 3 separate circuits containing i1, i2, A-B, respectively?


texts: What is the difference between a 120v 10 amp transformer and a 240v 5 amp transformer?

texts: I can't seem to find an answer for this online. What are the design considerations taken into account to determine the voltage rating of a transformer? If a transformer made in the U.S. is rated for 120v and intended to draw 10 amps, and its U.K. equivalent is rated for 240v and intended to draw 5 amps, what exactly is the difference between the two? What would happen if you connected a U.S. transformer directly to a U.K. outlet with its secondary open?


texts: How to convert a three wire hall effect sensor to a 2 wire sensor?

texts:
Would there be any possibility to convert a three-wire hallsensor to a 2-wire equivalent.
The connections are a V+, GDD and OUT.
The voltage between V+ & GDD would be 24V and the OUT port would reflect the influence of a magnetic field on the sensor.

I assume that if one would connect the wires in the correct way you could get an sum or subtraction hence enabling a 2-wire circuit.

Thank


texts:
I am designing a BUCK converter 24V/12V, 80A, 300kHz switching freq. It will be used for stepping down battery voltage, so it can be expected for input voltage to vary from 22 to 30 volts.

I am stuck trying to design a viable bootstrap circuit. The problem is that if I just put a diode from 24V rail to charge the bootstrap capacitor, it will charge to 24 volts which is too much for mosfet gate (irf3206, Vg=20V, Qg=170nC).
If I were to use a 10V zener in series with said diode, the capacitor would be charged to acceptable 24-10 = 14V, BUT in case where input voltage was 29V, it would be charged to 19V which is dangerously close to gate's absolute maximum 20V. Besides, turn-on times, and thus switching losses would vary wildly depending on input voltage.

Would it be a viable solution to use a LDO like 7812 between bootstrap diode and capacitor?


texts: RC Low pass EMI filter for IN-Amp, component specification

texts:
I want to implement a low pass filter in front of instrumentation amplifier as shown below:

In this this tutorial, it says "The overall differential-mode filter bandwidth should be at least 100 times the input signal bandwidth." But it doesn't explain why. What would be the effect if I have the cutoff frequency just above the signal bandwidth?


texts: I want to know how high voltage generator works

texts: This is the product im reffering to. I have seen this product being used in many DIY and wanted to know the circuit it uses and how it is able to step up the voltage so high in such a small space and price.


texts: AVR interrupt service routine not executing as fast as expected (instruction overhead?)

texts:
I'm developing a small logic analyzer with 7 inputs. My target device is an ATmega168 with a 20MHz clock rate. To detect logic changes I use pin change interrupts. Now I'm trying to find out the lowest sample rate I can detected these pin changes. I determined a value of minimum 5.6 µs (178.5 kHz). Every signal below this rate I can't capture properly.

My code is written in C (avr-gcc). My routine looks like:

ISR()
{
    pinc = PINC; // char
    timestamp_ll = TCNT1L; // char
    timestamp_lh = TCNT1H; // char
    timestamp_h = timerh; // 2 byte integer
    stack_counter++;
}

My captured signal change is located at pinc. To localize it I have a 4 byte long timestamp value.

In the datasheet I read the interrupt service routine takes 5 clocks to jump in and 5 clocks to return to the main procedure. I'm assuming each command in my ISR() is taking 1 clock to be executed; So in sum there should be an overhead of 5 + 5 + 5 = 15 clocks. The duration of one clock should be according to the clock rate of 20MHz 1/20000000 = 0.00000005 = 50 ns. The total overhead in seconds should be then: 15 * 50 ns = 750 ns = 0.75 µs. Now I don't understand why I can't capture anything below 5.6 µs. Can anyone explain what's going on?


texts: How is the phase of a local oscillator synchronized to the carrier for demodulation?

texts:
How are phases of a wireless TR/RX pair synchronized for coherent demodulation?

I understand PLLs will match the frequency of the local oscillator to the carrier via maintaining a constant phase difference between the received signal and the local oscillator but for coherent demodulation the phases of the oscillators need to also be synchronized(at least as far as I understand).

How is this done?


texts: Current Measurement. 50Amps 0.5% error margin

texts:
I am working on a solar energy project and I'm using a 10 panel array. For monitoring purposes I'm using a combiner device which tracks various data parameters like current, voltage and temperature. This combiner device should be able to withstand a 50A current and give current measurements with 0.5% error rating.
Now I have already tested 2 different methods and faced the corresponding problems.

Hall effect based sensors: For the sensor I selected, I was still getting 1% to 2% percent error in ideal conditions and the sensor was going out of my budget,too.
Shunt resistor: I was able to find some shunts with 0.5% error, but the problem was with the dissipated heat. On longer testing cycles the Shunt PCB was getting extremely hot. I tried different design techniques:changing shunts, track width and others. Still,on long testing cycles.the heat dissipation was beyond acceptable for my application.(I've added an image of the same below)

Now on searching for other techniques online, I found some using an inductor, current transformer, transistor. But I have no experience or knowledge of their capabilities. I need help to choose the best technique for current measurement with 50Amps and 0.5% error margin and also not too expensive.
Thank you!


texts: What are the standard PWM output signals that a microcontroller should generate for 3 phase motor control?

texts:
I am programming a FOC 3 phase motor controller on a Teensy4. The motor will be driven by 6 MOSFETs and a gate driver IC for the MOSFETs.

I have looked though the data sheets for many different gate drivers and they don't have any images of the signals required for their inputs from the microcontroller. Some have 3 inputs, which I assume is just a basic sinusoidal PWM signal going from 0-100% duty cycle as the sine goes from -1 to +1.

However most have 6 inputs. Are these 6 inputs standardised? My guess is that 3 are for the high side MOSFETs and 3 are for the low side. The PWM signal for the high side going from 0-100% duty cycle as the sine wave goes from 0 to +1, and the low side PWM going from 100-0% as the sine wave goes from 0 to -1.


texts: A conceptual question on turning power on/off for a wireless communication

texts:
I want to interface a wireless modem with a micro-controller.

What I want to achieve is that when I send a signal to the wireless modem I want the power to be turned on and when the modem does not receive any signals I want the power to turn off.

How can this be possible?

Here below I want to turn on off Power_gmod.


texts:
I am using DRV8834 IC driver to run the 5v stepper motor. I've managed to run the 5v stepper motor using DRV8834 IC by using a breadboard. But I've found we need 3 pins (Step, Direction and enable) to enable and step the device. I came to know that by making the enable pin to high makes the driver disable where there is no power consumption in the whole system.

But the requirement is only to use 2 pins (step and direction). If I don't control the enable pin via microcontroller then the driver and motor (whole system) consume 50mA. I have to find a solution where the driver and motor shouldn't consume any power until enable line receives the step output pulse from the microcontroller.Also, the step output will always stop in the low state. Is there any idea you can help me with to use any MOSFET/any other idea/pulse stretcher to control the power consumption without using the enable pin? Please let me know if you guys got an idea. Your help is much appreciated.

Update to clarify @Transistor's answer.

simulate this circuit – Schematic created using CircuitLab


texts:
I've created a simple controller with a nodemcu to connect a RGB strip that I had to the internet.

The thing that happens is that when I go to plug in the nodemcu to my iMac(to power the nodemcu), I see small sparks on the metal casing of the iMac appear until I fully plug in the USB. I don't know if this is a problem because I've had this working a while and it still works just fine and causes no problems, I'm just curious.

I created a simple fritzing diagram below:

Is this right? I have IRF540N N-Channel Mosfets and 470ohm resistors. The 12v power supply is there to power the RGB strip.
One thing to add is that the mosfets get quite hot when under use does anyone know how to fix this?


texts: In microprocessor 8085, how can I clear/reset all flags(s,z,ac,p,cy) without affecting contents of accumulator?

texts: I only know the code in which accumulator contents are affected. It is not a duplicate as I have asked for a solution which doesn't affect accumulator.


texts: IC boost converter performs poorly in breadboard prototype circuit: is this to be expected?

texts:
I'm using a TLV61220 IC boost converter to get 3.3V from a 1.5V AAA battery. I've built the circuit as specified on the datasheet (p. 1 of http://www.ti.com/lit/ds/symlink/tlv61220.pdf) with R1 at 1MΩ and the appropriate value for R2. The converter outputs 3.3V as expected with a small load, but appears not to be able to handle loads that draw more than a couple of mA (the output drops to about 1.8V with a 1K load, for example). The battery should of course be capable of supplying much more current than this, and figure 3 on p. 7 of the datasheet suggests that the converter should be too.

I was wondering if this sort of performance is to be expected given that the prototype circuit is on a solderless breadboard (and that the TLV61220 is hooked up via one of the crappy SOT-23 to DIP converters sold by Digikey). I've read that high frequency circuits do not perform well on breadboards, but I'm unsure whether it's plausible to put the extremely poor performance down to this factor alone. On the other hand, if the circuit was not hooked up correctly, then it seems unlikely that I'd be getting 3.3V output with small loads.

(I've tried with two different TL61220s with exactly the same results.)


texts: How do I calculate constant values across several modules at compile time in Verilog?

texts:
I have a Verilog module that uses three instances of the same low-level module, called 'pole'. The instances are identical, except for a constant offset value, which is provided by the top level. There are other constant values within 'pole' as well.

Here's a rough pseudo-code concept:
(please forgive any syntax typos, I'm just trying to illustrate the idea)

module toplevel{
    localparam offset0 = 0;
    localparam offset120 = 120;
    localparam offset240 = 240;

    pole myPole0(offset0, variable);
    pole myPole120(offset120, variable);
    pole myPole240(offset240, variable);
}

module pole{
   input offset;
   input variable;

   localparam x = 1;
   localparam y = 2;
   localparam z = 3;
   localparam transitionConst = x + y + z + offset;
   reg transitionPoint = transitionConst + variable;
}

'variable' is dynamically updated during operation, but is consistent across each instance of pole. 'offset' is statically set at compile time, but there is a different offset value for each pole.

I want to calculate the total of the constant values (transitionConst) for reg transitionPoint at compile time. How do I do this?

I tried using a localparam as shown above, but this gives me compilation errors at the 'pole' level because offset is not a constant. Obviously, I know that I will be providing offset as a different constant for each instance of pole, but
the compiler doesn't know that. Is there an easy way to add constants across multiple modules at compile time?


texts:
I want to display 2 or 3 images in a loop (every 5 seconds or so) on a 3 inch TFT. The TFT can be found here, Resolution 240x400 Screen 3 Inch Tft Lcd with MCU Interface

It uses an MCU interface, I am looking for the easiest way to drive this display. I have done some Arduino stuff before, could I drive this display with an Arduino and display images such as JPEGs on it?

I'm always nervous when it comes to buying these parts from Alibaba, because I don't know if there is a library that will drive the display or not already. I'm also trying to do this as cost effectively as possible and was planning on driving 10 of these display for a mini project that I am working on.


texts: How to go about debugging PCB Power Supply Circuits to ensure correct output voltage?

texts:
I'm currently soldering, testing and validating the components on this PCB that I designed a few months back.
As it is right now I have soldered the 1.2V, 2.5V, 3.3V and 5V buck converter power circuits and that schematic is shown below.
I have done continuity tests to check for shorts, that passed, and also haven't found any solder bridges. After continuity testing, I decided to power it just to do some initial testing of the output voltages for each converter to make sure the power planes were getting the correct voltages.
This is the part I'm not fully understanding. When I check each output capacitor I get the same voltage as my Input Voltage (~15V).
I can't figure out if this means that every converter circuit is either designed poorly, soldered incorrectly, or an incorrect testing method. My current thought is that I'm completing the circuit from the power adapter, at my output capacitors, and reading the input voltage. That leads me to wonder if I need a load to test the output voltage correctly and how that could be implemented on a PCB that utilizes SMD components. If you have any suggestions I would appreciate it!


texts: How can I use the TI ADS1243 8-channel ADC to convert a line-level audio signal (ideally balanced) to a digital 24-bit (as stated on data-sheet) stream.


texts:
I would like to use an Si514 as a tuneable oscillator driving later stages with 50 ohm impedance.  So I put an opamp on it and attempted to configure it as a saleen-key low pass filter (to round the squares).  The problem I have is, although it works, the output is 5mVpp if my cheap oscilloscope is to be believed.  My fluke multi-meter on DC says 1mV at J2 with no coax hooked up.
The first thing I know I did wrong is I accidentally swapped the + and - of my opamp when transcribing the circuit.  An online circuit simulator doesn't seem to care about this fact.  Nevertheless, is this the issue or is something else wrong?

Channel 1 is a coax cable attached at J2.  Channel 2 is a probe touching the oscillator side of R1.


texts:
I am new here.
I am trying to write VHDL codes for my FSM that has got 3 states : s0,s1,s2
At reset it comes to S0 and then if start is one goes to s2 and stays there for 12 clock cycle and then goes to s2 and then in s2 if done =1 goes to s0 again.
here is my VHDL code for it but it is not compiling .

Could someone please help me out here.

Thank you

library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_arith.all;

entity state3_fsm is
  port (
    clk_H : in std_logic;
    res_H: in std_logic;
    start : in std_logic;
    done_H : in std_logic
  );

end entity state3_fsm;

--
architecture arc of state3_fsm is

  type statetype is (s0,s1,s2);
  signal pr_state ,nx_state : statetype ;
  constant clock_delay_12 : integer :=12;
  signal s_counter : std_logic_vector(3 downto 0);

begin

  ff_pro : process (clk_H,res_H)
  begin
    if (res_H ='1') then
      pr_state <= s0;
    elsif (clk_H'event and clk_H = '1') then
      pr_state <= nx_state ;
    end if;
  end process ff_pro;

  com_pro : process (start,s_counter,pr_state,done_H)
  begin
    case pr_state is
      when s0 =>
        if (start_H = '1') then
          nx_state <= s1 ;
          else nx_state <= s0;
            end if;
      when s1 =>
        s_counter <= s_counter + 1 ;
        if s_counter = clock_delay_12  then
          nx_state <= s2;
          s_counter <= '0';
          else nx_state <= s1;
        end if;

      when s2 =>
        if done_H ='1' then
          nx_state <=s0;
        else
          nx_state <= s2;
        end if;

      when others =>
        nx_state <=s0;

    end case;
  end process com_pro;

end architecture arc;


texts: SIM800L EVB audio output on Raspberry Pi

texts:
I have a SIM800L EVB GSM module connected to a Raspberry Pi and it is working correctly. However I did not find any pins related to speaker or audio output as shown in the wiring:

This is different than the old model which has pins for speaker and audio:

What am I missing here?


texts: Why is it required in radio receiver to tune the LC circuit to the the resonant frequency of the station in order to receive the station ? How this tuning filters the desired signal from the other signals. Can anyone explain this to me please ?


texts:
I was given the system defined by the open-loop transfer function:

\$L(s)=\frac{5(s^2+1.4s+1)}{(s-1)^2}\$

I was told to use the Nyquist criterion to determine stability. Examining the Nyquist plot shows one CCW encirclement of the (-1,0) point. The open-loop system has two RHP poles (although they are repeated poles). Using the equation:

\$Z=N+P\$

Where N=-1 and P=2, we see Z=1. This means there should be 1 RHP pole in the closed-loop transfer function and we would expect the system to be unstable. However, upon inspection of the impulse response, and step response the system does in fact appear stable. I'm struggling to understand why this system is not unstable. My initial thought is that the repeated pole at s=1 should only be counted once, but I haven't been able to find any literature to suggest this.


texts: How to start implementing your own computer?

texts:
The question

As a first step I need to select a circuit board, CPU & RAM/ROM chips and I/O connectors. How do I select a board that can interconnect all these components? Perhaps you could give examples of a full configuration (board and chip models). What type of board would you recommend for a beginner (solderless, stripboard, PCB, ...) ?

Project Outcome: create a motherboard by myself to which I could connect a monitor and a keyboard and the monitor would display the keys I've typed. An additional extension would be receiving and sending data from a network interface.

Question background

I have a fairly decent background in software development. However I would like to start doing some hardware projects in my spare time.

I've been looking around on the internet for materials to understand how programs are executed on hardware. Two great resources I've found are the http://nand2tetris.org/ which I am currently undergoing and the raspberrypi motherboard which seems like a simple hardware platform to write your first OS. Given the understanding I can get about the basic workings of operating systems from those resources I would like to start to assemble my own motherboard using standard ICs and write programs for it.

Could you give some initial pointers on where to look for information regarding such kind of projects? In particular I have no idea which ICs would make up a working computer, which kind of board to use to assemble them, how to create the circuits between the ICs. Any kind of information on those basic things would be useful to get me started.

UPDATE:

Since the question seems to be considered vague (how else it could be if you need some kick-start information on an unknown topic) I would like to emphasize that I know programming (Java, C/C++, Python, Assembler x86), i've also done some projects in tools like OrCAD etc. The problems I am struggling with are:

 I've never learned the basics for working with physical components
 I have little knowledge in components other than general purpose CPU and RAM/ROM chips and how they interconnect with CPU and memory chips in order to make a working computer (the clock, power supply unit, keyboard/monitor/network interface units)

So given all this I need some pointer to resources that contain step-by-step instructions on buying the necessary components and assembling them into a working mini computer. An example of such a resource is the one given by Alfred Centauri in the comments below. [A Homebuilt Z-80 Computer].


texts: Why is this MOSFET showing this behaviour?

texts:
I have solar charge controller PCB in which I am using MOSFET IRF9540. I am using ATmega328P as microcontroller to read the voltages of battery and solar and to enable/disable the charging process. Below is the schematic:

Now in the above schematic, I am giving solar voltage at X1 connector. R1 and R2 are used as a voltage divider and its output is going to an analog pin of the microcontroller. CHARGEPIN is a GPIO of the microcontroller. So when this GPIO is high, it turns on the transistor, which then turn on the MOSFET and solar is then connected to the battery to start the charging process. When the GPIO is low, solar and battery are disconnected. I am also using a serial port to monitor the voltages.

Now what's happening is when I have not connected the solar pins and only connected the battery pins. At that time, charging is off (because we do not have a solar voltage), so CHARGEPIN is low thus, the MOSFET will be OFF. So solar and battery should be disconnected. But somehow battery voltage is going to solar voltage because when I read the voltage at the MBR2045 diode, it shows the battery voltage, which should not show because the MOSFET is OFF. Why is the MOSFET acting like this?


texts: How to add a low frequency dither signal in a bias-tee?

texts:
I am driving an optical modulator with a driving signal with DC(2 V)+RF signal(bandpass signal from 1GHz to 2GHz, 500 mVpp). The DC and RF are combined with a bias-tee (mini-circuit, ZFBT-6G+). The passband of the RF port of this bias-tee is 10 MHz to 6 GHz.
However, I would like to add a 1 kHz sinusoid dither signal to the driving signal, to monitor the working status of the modulator. The problem is, 1 kHz is too low for the RF port of the bias-tee.
Is there any suggestion on this?
Intuitively I came up with the idea to feed in the dither from the DC port, not the RF port. I tried to search whether the DC port of the bias-tee can get the 1 kHz dither in but google did not give me any clue.
Thanks in advance.


texts: PWM and MPPT charge controller on same solar panels

texts:
I have two identical solar panels in series that are connected to an MPPT controller (EPEver Tracer 1210A), which is currently charging two SLA batteries connected in parallel meant to power some lights.
The overall solar panels wattage is 200Wp, whereas the MPPT is meant to support 130W at 12V.
I bought LiFePo4 batteries as I plan to power some tools so I need larger battery capacity. This however leaves me with two perfectly fine SLA batteries that I'd much rather re-use somehow. I know I can't connect the two different battery chemistries directly in parallel, so I'm trying to work out different solutions.
I have a spare PWM charge controller (your typical random chinese brand), so I was wondering whether I can connect the series of solar panels to both the MPPT and PWM controller (assuming the latter can tolerate the voltage of two panels in series) without causing strange behaviours (on the MPPT controller in particular, given the power tracking features) or other problems on either controller.
The MPPT controller would be used to charge the LiFePo4 batteries, whereas the PWM controller would charge the SLA batteries. You can assume that both chargers have embedded reverse-charging protection, so the batteries won't be drained at night.
Is this a sensible setup?
Here follows a diagram. Apologies if it's not perfect: I'm not used to drawing electric diagrams.


texts: Interfacing barcode scanner with microcontroller

texts: I am doing a project involving barcode scanner, netduino plus 2(microcontroller). I came across different types of interfaces(pin standard used such as USB etc..) for barcode scanners which are Keyboard wedge, RS232, USB (which again acts as keyboard wedge or RS232). I shortlisted datalogic QW2170 (barcode scanner) which supports both USB and RS 232. The USB interfacing is of plug-n-play type. I was wondering if i can use USB (use usb cable from barcode scanner to connect to netduino plus 2) interfacing to capture the stream of data coming from barcode scanner after scanning barcode (to be specific 1D barcode) and save it in the microsd card (netduino plus 2 has a slot for microsd card upto 2 GB) or do i need to use a RS 232 interfacing for this purpose.


texts:
I want to use Eagle or Kicad to design a board using Maxim chips MAXQ1103 and MAX32550

http://datasheets.maximintegrated.com/en/ds/MAXQ1103.pdf

and

http://datasheets.maximintegrated.com/en/ds/MAX32550.pdf

MAXQ1103 is 144 pins TQFP package (see page 1 of the above datasheet)

while

MAX32550 is 121 CSBGA package   (see page 2 of the above datasheet)

The question is i am not able to find these parts in the Eagle's library (my google search didn't help me much). Where can i find these parts or do i have to create myself? If so, is it really worth the effort (how hard is it for Eagle beginner)?

The reference schematics of both these chips are done in Cadence ORCAD, which is very expensive to purchase.

Thanks


texts: How to insulate DC from earth noise while keeping it referenced to it

texts:
I have an AC/DC converter (220 to 24) inside an electrical cabinet. The 0VDC is referenced to earth, like this (couldn't find a symbol for an AC/DC converter in the schematic editor so I made a dirty sketch):

I've noticed there's a bit of noise on the output line:

I assume it's not coming from the AC input side because the converter should have a big capacitor there. I assume it would suppress all this high-frequency noise? So could the noise be coming from the earth connection?

If so, can the 0 still be referenced to earth, but without receiving all the noise from it? Would a ferrite bead help? I don't know if they make them for DIN rails, though.

Edit:

The voltage between the cabinet chasis and 0 output of the converter produced the same image. Measuring between two small bus bars for zero and earth created a different image though:


texts: Saturated BJT Transistors. \$V_{CE} < V_{BE}\$ : AKA - Things that make you go "Hmmmm"

texts:
We use them every day and those in the know fully understand the functional characteristics of BJT transistors. There are documents and links galore explaining the operational math. There are even tons of nice videos that explain current theories of how they physically work. ( Most of the latter given by folks that speak "Tele-marketer English" for some reason. )
However, I have to admit, even after 40+ years, a lot of it I have to accept at face value, since the descriptions of how the collector junction fits into the equation is always a bit hand-wavy.
Anyhow, that aside, there is one facet I really just don't get. It seems to defy the laws of physics, Kirchhoff's Laws et.al.
I'm talking about your standard saturated common emitter circuit.
It is known, and we accept, that when saturated, the collector voltage will be less than the base voltage. We obviously use that to our advantage in circuits and chose parts to give us as low a Vce-Sat as possible for a particular load current.

simulate this circuit – Schematic created using CircuitLab
All fine and dandy, till you look at the quintessential mode of a typical NPN transistor...

How the heck can the collector be a lower voltage than the base in that sandwich?
Even if you add in some back-EMF type voltage in there to account for it, the collector current would be going the wrong way through the base-collector junction..


texts:
How to build a 555-circuit IC with a delay at the beginning and a delay at the end?
I want to make a LDR switch that When it gets dark Turn on the relay after 10 sec and When there is light Turn off the relay after 10 sec.Please help me build this circuit


texts: Can massive ammounts of 0603 SMD 1uF ceramics displace power caps?

texts:
Edit:Warning: there's an error in one of my assumptions in this question, which more or less invalidates it. See Tom Carpenters answer.

I'1m designing a switched mode power supply, and of course need various capacitors in the design.

For instance, to spare the mains from all the noise from the switching action, I'm thinking about building an LC filter with a 3uF capacitor.

So now I've been trying to source 3uF capacitors. Of course it's not difficult at all to source a 3uF 450V capacitor. Polypropylene caps seem to be suitable.

But the cost of a capacitor capable of handling at worst 1A of ripple current, is signficiant (say 5 euro). See for example.

However, 1uF ceramics can be had almost for free, see for instance. 2000 caps for ~13 euro.

If I put the 1uF 100V caps 15 in series, 3 in parallell, I need 45 caps. This will cost approximately 0.3 euro.

Of course I'll need some resistors to balance the caps. Placing the caps at a reasonable distance I calculate that they would all fit within a 12.5mm x 12.5mm box, which means they take up a fraction of the space of the Epcos one.

One possible problem could be that DC bias reduces capacitance of ceramics. But for my application I need approximately 400V, so with 15 in series the 100V 0603 caps are loaded only marginally, and should retain most of their 1uF capacitance.

I'm not really considering doing this, but would it work? Or will the 0.3A+ ripple current kill the little 0603:s?


texts: How hot does a lithium-ion phone battery have to be before it explodes?

texts:
I have an LG G4, model LG-H810 (serial indicates it's one of the shoddy-soldering ones) and it gets extremely hot during light gaming or while watching videos. It's not too uncommon for me to pick it up by the case and burn myself. I'm concerned that my battery might explode due to the extreme heat. The battery is OAM.
I've seen temperatures of up to 80 celsius (176 farenheit) as reported by both a contact thermometer and CPU-Z. Is this hot enough to cause an explosion?


texts: How can I solder to stainless-steel semi-rigid coaxial cable?

texts:
I need to run coaxial cables into a cryostat, and because copper conducts too much heat, I decided to use semi-rigid stainless steel cables. As far as I can tell, both the shield and the inner conductor are made of stainless steel. I want to connect this cable to electronics in the cryogenic region, but the connection must be non-magnetic. My standard electronics solder does not wet the stainless steel at all.

Are there special fluxes or surface treatments so that I can solder to stainless steel?

Update: Thank you all for your comments and for the answer! I tried different soldering approaches and wrote my own answer below. I'll wait for a few more days, and then accept the answer with the highest vote.

As for RF or DC: There are several cables, some with DC, some with RF, some with both. The DC needs to be extremely stable (10 µV), but only needs to be precise on a 10 mV level. This stability requirement makes thermovoltages very relevant, which is why we want everything that sees the temperature gradient to be made of the same material. The RF has to be as clean as possible (I don't have numbers, here). I think the special problems with sending RF and DC voltages into a cryostat could best be separated into another question.


texts:
everyone.
I have a really simple power input network like so:

The SMPS will power analog devices with +12V and the regulator will regulate the rest downstream to power digital circuitry with +5V. Additionally, I have two sense terminals on the board that will take measurements of an attached load. The - terminal is connected to ground with everything else. This throws a wrench in my workflow with respect to reverse polarity protection at the sense terminals. If I hook up something in-between 5 and 12 volts or maybe higher on the negative side, I'm afraid my current setup wouldn't be enough and it could damage chips. Should I consider placing a barrier diode on the OUT side of the regulator as well? What are your layout recommendations in regards to protecting against a positive voltage scenario on the - sense terminal?
Thanks in advance.
Edit: I've added more of the schematic for clarity.


texts:
I have a DAC using MCLK from an oscillator. All literature that I read suggest  to ground it to analog ground. However the output of my DAC (analog output) is also close by and I am afraid that my (48MHz) oscillator will inject noise in my sensitive audio signal.

Am I right to build a "fence" to keep the 2 analog grounds separated? Can you suggest the best way to isolate the noise?


texts: Is there an audio amplifier chip or circuit that amplifies certain amplitudes in a signal less or more than other amplitudes?

texts:
Like for instance, that would amplify on an exponential curve where the lower amplitudes get the maximum amplification and the highest amplitudes would get no amplification?

Is there an analog chip or circuit that could do this or is it something that would need to be done with DSP?


texts: JLNINK(SWD)+IAR can not debug stm32: communication error

texts:
guys. I am using J-link with SWD interface to debug my STM32F103VCT6 in IAR. I can enter download and debug mode but I can not use "step over" or "stop" function. Once I use one of them I will get communication error

and if I click "NO" , another dialog window will appear

I have tested STM32F103VCT6 with J-link commander, I can use basic command to find core:

I have already added a reset circuit( 5.6K + 30pF). can anybody give some suggestions？


texts: How data 0xFF is stored in Flash memory?

texts: Hi i am using SST25VF032B flash memory. Before writing ,it has to be erased to 0xFF. But my doubt is that how it stores real 0xFF. Will is store 0xFF or some other value?


texts: Why is the magnitude of mutual flux in a transformer independent of the current in primary?

texts:
Consider a transformer with no load,

Given \$\phi= \phi_m \sin (\omega t)\$
\$e_1 = N_1 \dfrac{d \phi}{dt} = N_1\omega \phi_m \cos (\omega t)\$
\$E_1 = e_{1rms} = N_1\omega \phi_m \ \frac{1}{\sqrt{2}} = 4.44 \phi_m N_1 f\$
Since the supply voltage \$v_1\$ is fixed, in order to satisfy Kirchhoff's law: \$v_1=e_1\$
\$\implies V_1 = E_1 = 4.44 \phi_m N_1 f\$
Therefore, the maximum value of \$ \phi\$ is determined by the supply voltage and frequency (given the remaining  terms are constant)
\$\phi_m = \dfrac{V_1}{4.44 N_1 f} \$
Therefore even when the current is the cause of flux, the magnitude of flux is determined by the supply voltage.

I understand this fact mathematically. But why is this fact true, intuitively or physically? (I'm not really sure what I mean by intuitively, but if there's a different perspective on this, please do share)
The second question is kind of arbitrary: When we consider non-linearities of the B-H curve, it's the current that becomes "peaky" to keep the flux sinusoid, why is this true, isn't current the cause of \$\phi\$, why doesn't \$\phi\$ alter to draw a sinusoidal current?


texts: May I use CD4066 instead max 232, to convert rs232 UART(USART) level

texts:
As in the title, Is it possible to use the CD4066 as level driver through RS232 and TTL(USART)?
If it's possible how this work.
Thanks.


texts: Why is the TP4056 IC called a "linear li-ion battery charger"

texts: Being new to electrical engineering, I'm wondering why the TP4056 IC is called a "linear li-ion battery charger" (emphasis on linear). Is it because the TP4056 is designed to work with a constant voltage/current input? Or is it linear as in "linear power supply vs switching power supply"?


texts:
I'm using a PIC16F1824 with an external 4MHz oscillator.  I actually want to use the internal oscillator, but the timing seems incorrect.

For example, I tried to use delay_ms(1000), and it delayed 5 seconds instead of the expected 1 second.

What did I do wrong?

Data sheet:
http://www.microchip.com/wwwproducts/Devices.aspx?dDocName=en546901

I'm clueless reading the OSCCON details:


texts: Why is a horizontal rod a full wavelength oriented radially to a broadcast antenna not the best receiving antenna

texts: I have always struggled to get a good physical understanding of Electromagnetic waves. I've done the whole Maxwell's equation approach, wrote boundary element solver tool but cannot rationalize that with a phenomenological understanding of E/M. The waves propagate radially from a broadcast antenna, so you have a time/distance varying electric field in a radial direction. A full-wave horizontal rod with feed taps at 1/4 and 3/4 of its length seems like it should be the best receiver. Help me get a better understanding, if I am wrong.


texts:
I'd like to turn on a broken laptop LED backlight  without laptop and use it as light panel.
How can I do it?
Thanks


texts: What is this socket name and where can I buy the female counterpart?

texts:
I have this socket on a PCB which is half inch wide (1.27 centimeters) with pins being close together (I think 0.05") and not uniformly spaced like in a normal IDC connector.
I need to create a ribbon cable from 6-pin JTAG to this socket: what is this socket name and where can I buy the female counterpart?

(pics from a 3D model)


texts:
I will buy a custom made 47.5 amps multi tap transformer .of course i will use full wave bridge rectifiers(e.g mda5010) to convert to DC.I want to build a dual channel linear DC power supply 20 Amps each channel.I will switch the taps so there is minimum heat generation i.e use one tap for low DC output voltage and switching to higher voltage tap for higher output DC voltage.
questions:
1) can i get 5 amps between 0 and 6v and 10 amps between 0 and 12v taps?e.g one channel consumes 5v/5amps and the second channel consumes 9v/10amps.
2) should i use isolated taps like the above image
or i should use non isolated taps like the below image?.

3) where is the best position for ground or 0V?.
4) what voltages will be the best to wind the taps for?Remember i will wind the transformer from a local shop.I haven't bought yet.I intend to use the power supply for lab work,charging 12 and 24v lead acid batteries 3.7v lithium ion  batteries and testing different things in a typical electronics lab.
5) can i switch the output pass transistors to get 40 amps single channel/20 amps dual channel or will i have to parallel two channels to get 40 amps if each channel is 20 amps or is there any other way of doing it?.
6) what is the upper limit on current that i will need in maximum situations?
7) any ideas for good heat sinking.I have got many small computer power supply fans
8) how much capacitance value should i use per channel?
9) which type of switches will best suit my case to switch the taps?


texts:
I'm trying to power a 12V 1A device with 1 cell lipo battery. At 12W, the lipo would need to provide 3.24A (assuming no power loss) to step up the voltage to 12V and providing 1A.

However the DC-DC Boost coverter (XL6009) is rated at 2A continuous input. So I've decided to connect 3 DC-DC Boost converter in parallel, so each of them share the load and keep everything cooled down. Did some googling and I'm not sure if this is a good idea, some say the small different in output would fry the converter with lower output over time.

My question is should I do this at all? If so do I need a diode to deal with the different in output voltage? And if so what diode should I use in my case?


texts: Measuring battery with low power requirement

texts:
I am trying to create a low power device, which would work off a LIR2450 or similar coin cell battery. athe device has long periods of sleep with short periods when it performs operation (e.g. reading sensor and/or sending LoRa data).
For this purpose, I am using an atmega328p. The idea is to have a stable 3.3V out of a voltage regulator and correct battery reading over the voltage divider R9/R10.
Here is the relevant part of the diagram:

I have selected high resistance values for the voltage divider in order to reduce current (this might have been a bad idea).
I am getting readings of Vmeas, but depending on the battery voltage they are somehow - not consistent. When I have approx. 3.5V I seem to get around expected measurement of ADC, however, with around 3V or 4V the readings are strange - either lower than expected or sometimes higher, as if the ADC is not linear in its readings.
How do I measure:
// calculate Vbat from adc value, assuming Vbat:Vmeas is over the resistor-devider 1M:2M
float adcVbat(int adcV) {
  // first calculate adc measurement (10 bit adc - reference 3.3V)
  double meas = ((double)3.3) * ((double)adcV) / 1023;
  // calculate Vbat from voltage devider
  double result = meas * (R1M + R2M) / R2M;
  return result;
}

// read Vcc in miliVolts
long readVcc() {
  int adc = analogRead(A6); // read ADC
  return (adcVbat(adc) * 1000);
}

Do you see anything wrong with my concept and should it, in general, work as I expect?


texts: 48V DC Power Supply Using LM7812 in Series

texts:
I want to create a 600W 48 VDC power supply with input taken from the line (220VAC) and so far the steps that I've had in my mind are:

Stepping-down the voltage to 15V using transformer with 3A current rating.
Rectify using bridge diodes.
Use 4 pcs. of LM7812 (linear voltage regulator with 12VDC output) to generate 4 12VDC voltage source.
Connect the output of LM7812 in series to produce 48VDC voltage regulator.

Will this method works or is there any flaws in the method I have? Is there any better method? Any suggestions are welcome.

Thanks.


texts: Why dc motor is buzzing when using it with XL6009 converter?

texts: I have the following scheme RPI, L298n with 6v DC motor. I'm trying to add a XL6009 boost converter but set to boost 5v into 6v but sometimes the motor is rotating and sometimes is buzzing. Does this have any connection with PWM? I would like the motor to rotate all the time when I run my code. Without XL6009 is working without any problem.


texts: When I try making the concatenation mapping below, I get the following outputs. Is there anything in particular that's wrong with my mapping ideas?


texts: Input change notification not interrupting after sleep()

texts:
I have quite a large codebase running on a PIC24F (PIC24FJ128GB106) and have a Change Notification IRQ handler managing external inputs from the user. Everything's been working well for quite some time, until I changed some clocking to slow the CPU down to it's FRC oscillator during standby.

The problem I'm finding is that one single CN interrupt source isn't triggering the interrupt correctly anymore (the CNIF flag isn't being set), but is still waking the system up from sleep() mode.

All the other external sources which I'm running through this handler are setting the IFS1 register CNIF bit and then immediately entering the IRQ handler after sleep() and being processed as I'd expect.

The troublesome source is waking the system from sleep() then running the next 10 or so lines of code after sleep(), THEN triggering CNIF and entering the interrupt. When it finally goes through the interrupt, the startup conditions have changed and it's redundant.

Everything else is working as before, which is why I'm at a loss. To my knowledge nothing serious was changed.

CN priority is at 7, I've enabled all CNEN bits for each individual source, I've checked all other sources and they all raise the CNIF flag and the CN interrupt enable bit is set. The actual source I'm monitoring is definitely alternating between 0 and 1 (it's a 12v trigger line) when off/on.

Are there any glaring things I might not have checked here?

Edit:

It's worth mentioning this one external source also causes MPLABX to breakpoint at an imaginary breakpoint after sleep().

...
Sleep();
/* Woken up! */
}

The code breakpoints ON the closing brace. I can't stop this happening on this source, but there seems to be no clear reason why. No breakpoint set up, traps, RCON seems OK etc.

All other sources (there are 3 other CN enabled sources) work correctly...


texts: program works even when hexfile size is greater than flash memory

texts:
I am working with AT89S51 microcontroller and using keil to write program in C. It produced a hex file of size about 4875 bytes but flash memory on the microcontroller is only 4kbytes.

I programmed the flash successfully and the program is also working fine.

I am glad its working but I want to know why is it working since there is no enough space on flash to program my code on the microcontroller.

Let me know if you need any additional info.


texts: How to shift differential signal to read with single ended adc?

texts:
I'm using a current sense resistor (0.02 ohms) for a high current battery monitor for a hobby project. I'd like to shift this to a 0-5 V range to monitor using an ADC input (single ended.)

I understand how to set the gain of an opamp using a resistor network. I also understand how to use a differential input of an opamp. But I can't seem to figure out how to do both at the same time. The negative feedback resistor will cause a direct path to ground (this resistor is high side at 12-17V.) In the case of unity gain, there will even be a short!

So what am I missing?


texts:
I've just bought some 6mm^2 copper wire for my project where I will have large pulse currents - ~500A peak (driving very large Xenon flash bulbs, 1000J pulse in 2ms).

But I know that skin effect make it useless to use thick wires on high frequency, but does it apply to sharp fronts? Is that correct that having multiple non-isolated wires make it even worse? (mine cable have about 20 tiny 'wires')


texts:
I am attempting to build the following circuit using an LM6171 op-amp. I know that this op-amp is unity-gain stable. I previously had this circuit working with an LT1637 op-amp, but I had to switch parts for a higher GBWP.

simulate this circuit – Schematic created using CircuitLab

I want to put a low amplitude sine wave (10 mV, peak-peak) on the input. The output is connected to a low impedance load (< 10 ohms) through a relay, which is normally off (so normally open circuit).

When I switch on the power, the output shows a ~20 V, 20 MHz sine wave (without me applying any voltage to the input). Why is this op-amp oscillating? I am not sure what part of the datasheet would give me a clue here - I figured that the main issue was the phase margin.


texts:
I'm trying to make an ultrasonic beam breaker circuit - a transmitter sends a continuous ultrasonic signal to a receiver, both placed in a straight line. When the beam is broken, a peizo buzzer turns on. When the beam is restored, the peizo turns off. I was thinking of generating the ultrasonic signal using a 555 timer, and found this. However, I have no idea on how to implement the receiver circuit.

Meanwhile,  I found an alternative way to make this project here, but I can't understand the explanation provided.

So, how can I go about implementing the ultrasonic receiver circuit? Is the receiver circuit given in the Electroschematics website the only way, or is there an better, simpler way to do this?


texts: How to decode the markings on an SMD choke?

texts: I have a broken Ravensburger Tiptoi pen for kids. I opened it and the choke L7 broke. It is SMD and marked 420. I found out that this could be either 42 micro or nano Henries. Question is, which is it, so I can order a replacement?


texts: Shouldnt the magnetic field at a certain angle be minimum in center of current loop?

texts:
Magnetic field is strongest at the center of current loop. But if it is calculated along a single magnetic field line like this: A and B are magnetic lines.

Shouldnt it minimum in the center since there would an equal force pulling it in opposite direction? Shouldnt it form an equilibirum?


texts: How to select the equivalent coupled inductor to a flyback transformer?

texts:
Given a recommended transformer with certain parameters (inductance, saturation current, rms current, dc resistance), how would you go about choosing the equivalent coupled inductor? All the coupled inductors I've seen state their values with the coupled inductors wired either in parallel or in series. However, the flyback transformers aren't wired in either configuration, so you don't seem to be able to directly compare the values.

For example, given the SRF1280-101M inductor, if I were to use it as a 1:1 transformer in a flyback regulator, what would be the equivalent inductance, sat
current, rms current and dc resistance?


texts:
Can anyone recommend a good place to go making PCB's? I'm particularly interested in places that also offer assembly, because this makes SMD parts an option.

GoldPhoenix is an option, but not the cheapest.
Anyone used OurPCB?
Any order time is OK- there is no particular rush, and the slowboat from China is just fine.


texts: How do I calculate the diode parameters for reverse polarity protection?

texts:
I understand that a diode allows current to flow in one direction only, and that inserting a diode in series with a power source will protect the circuit from a reverse polarity battery.

How do I calculate what capacity diode is appropriate? I want to minimize the voltage drop as the battery is a one cell lithium unit with maximum 4.2V.  The device (a camera) seems to shut itself off when the battery hits 3.8V.


texts: PCB design considerations for running 48 stepper motors

texts:
For a while now I'm working on a project where I want to control 48 stepper motors.

A pair of two motors is controlled by an Atmega8. All modules are connected as slaves on an I2C/TWI-bus with an Arduino acting as the master device.

A while ago I already posted a question about power supply issues and got many useful comments regarding ground loops, capacitors and PCB design. The main issue that the Atmega8s are not working properly anymore when I run more than 5 of the motor-control-modules simultaneously.

I've tried to implement most of the suggestions, but still have some questions for possible improvements:

Are the large capacitors at the VCC-input as well as next to the motors placed properly?
Is the layout of the "power-plane" designed properly?
Is the decoupling of the analogue ground any good?

One module with both steppers running takes up roughly 0.5A at the same time. My power supply should be capably of running all modules at the same time. I'm running a star-topography with thick wires between all modules.

Okay, so here is what the whole thing looks like (I2C-bus/resistors not displayed to keep it simple):

The circuit for each of the modules (0X10 etc.) is looking like this. Some notes about the different sections:

The two motors on the bottom right are connected to the ports PB and PD via darlington arrays
Connected to PC1/PC2 on the top right are two optical sensors for homing the stepper motors
PRG on the bottom is the programming port for the Atmega8

duostepper_RevC_schematic

The PCB design (40 x 60 mm) I plan to order looks like this. This is not implemented, yet!
duostepper_RevC_topbottom

duostepper_RevC_top

duostepper_RevC_bottom

UPDATE 2017-04-15:

I updated the power input section of the schematic with a beefier capacitor, additional 100nF-capacitors and a ferrite bead. I changed the motor-capacitors to 220µF as well.

In the layout, I implemented it like this:


texts: Should I gate SCRs on when reverse-biased?

texts: I've been told that it's a bad idea to gate SCRs on when reverse-biased. Is that accurate? I'm reasonably confident that the SCRs won't actually conduct reverse-biased whether gated or not; are there circumstances where that is not true? Are there other problems with gating a reverse-biased SCR? Increased losses? Decreased lifetime?


texts: Simulating digital and analog inputs on a PLC

texts: What would be the simplest way to interface digital and and analog inputs from a PLC to outputs on an AVR ATmega328? All I need to do is simulate different analog values and digital states.


texts: Driving LED with 555 timer and BC639 transistor

texts:
I am trying to produce an LED dimmer circuit using a 555 timer circuit and a BC639 NPN transistor. I know there are better transistors that would suit the task better, but the BC639 is what I have to work with.

I've got the 555 timer configured so that it is outputting a ~12V 1.4kHz signal.

I am using a BC639 NPN transistor to drive a white LED, with a maximum forward current of 50mA. I have put a 330Ω resistor in series with the LED so that the current is 26.36mA.

I'm trying to figure out how to make it so that the LED turns all the way off when my 555 timer is outputting the lowest average DC voltage.

I have been told that this is down to the value of R3. I have calculated a value for R3 of 51.4kΩ:

IC=26.36mA

hFE=120

IB=IC/hFE

IB=0.00022A

R=(V-VBE)/IB

R=(12-0.7)/0.00022

R=51.4kΩ

This resistor value does not allow the LED to be turned off fully. Through trial and error I have found that the closest E12 resistor value that does allow the LED to turn off fully is is a 680kΩ resistor.


texts: Replacing a sound module's LCD/EL backlit display with a LCD/LED backlit display

texts:
I am attempting to upgrade my Kurzweil K1200 rack sound module's display with a LCD/LED display (it currently has an LCD/EL display). The reasons are numerous; but longer life, brighter display, and being easier to read are just a few. I try my hand at most DIY projects with success. However, I am stumped on accomplishing this task and hoping to solicit some direction so I can finish what I started. Here's what I've done so far: I have taken apart my module, and removed the LCD/EL display (Seiko M1632). I purchased an LCD/LED display from mouser (LCM-S01602DSF/C) http://www.mouser.com/ProductDetail/Lumex/LCM-S01602DSF-C/?qs=sGAEpiMZZMt7dcPGmvnkBkF%252b4jg01Mq8jGsitNZZC5U%3d

Connected voltage to the LCD seems pretty straight forward, just making sure the pinout matches. But, I am trying to understand how to implement a regulator and a resistor as pointed out on the K1000 website, where several people were successful in upgrading there backlights to LED (I have tried to make contact with them, to no avail). http://k1000.net/display-led.htm

The section that I don't quite understand is:

Driving the LED:

The LED backlight requires a circuit that will provide the correct current (depending on the product) Each product specifies the typical current required (100ma to 200ma) and the typical voltage at that current. (3.7 to 4.2). Michael's solution was to drop 11 volts from the power supply with a regulator to 5 volts (about a watt of heat), then drop the 5 volt (thus limit the current) from his regulator using a diode. Here is a simple solution (not ideal either). Just connect a 1/4 watt resistor from the 5 volt supply to the LED + connector. ( + 5 volts is on pin 1 or 14 of the display, Ground is on pin 2 or 13. Different vendors label the pins differently so check the data sheet). The value of the resistor (R) depends on the display you use. R= (5.0 - LED voltage)/(LED current). Example: If the data sheet says the LED requires 150ma at 4.2 volts then the resistor must drop .8 volts (5.0 - 4.2). R= .8/.15 = 5.33 ohms. Using 10 ohms would limit the current but might not be bright enough. Calculate the resistor for your display then experiment with the value to use. DO NOT connect 5 volts directly to the LED. If anyone uses any of the above displays, let us know how it goes and what value of resistor you used. For some other pictures and another way to drive the LED see the K1000 users group forum message dated Jan 27, 2010 - topic 1000 series lockups and updated display.

Michael's Method:

To power the LED back light, I tapped +11 volt unregulated from the C2 capacitor (K1000 power supply) leads on the power supply (after the 5 amp fuse). DO NOT USE the PURPLE wires used for the EL back light - you will destroy the back light (and perhaps start a fire). The +11 volts are regulated with a 7805 linear regulator (use bypass caps near the terminals) followed by a 1N4004 diode at the output (in series) to drop the voltage down to the 4.2 volts needed by the back light. Watch the polarity of the LED connections and polarity on C2. The regulator gets warm - I added a heat sink and bolted with one of the LCD display mounting screws. Leave the old purple wire connector to the power transformer unconnected - it is not used. Since the primary +5V regulator for the K1000 is rated at 2 amps and the fuse is rated at 5 amps, I figured I could tap this and regulate another 200 mA without overtaxing the PS and blowing any fuses.
-For LCD contrast control: I clipped pin 12 from the LCD header connector and wired a small 10K pot to pins 12 (wiper), 13 (gnd) and 14 (+5V) and attached to the backside of the keypad with glue gun. Alternately, a pot mounted thru a hole drilled in the back of the K1000 would offer external contrast control to the user.

Any advice or direction is greatly appreciated.


texts: Logic in displaying numbers in 7 segment 4 digit display

texts:
what is the logic in displaying desired numbers in 7 segment 4 digit display.
Ie, how to know the leg combinations to see the desired number in the display


texts:
I'm studying about Ohm's Law, and the following problem perplexed me.

The answer is \$I_{t} = 11\$mA and \$U_{r} = 41\$V.

What I need to find is \$U_{t}\$ and \$I_{t}\$. The only thing I've found so far is the total resistance:

$$R_{t}=\dfrac{41}{11}\Omega$$

Can you help me to understand it?


texts: Is there a good reason not to name most digital signals in the flavor of COPI/CIPO (MOSI/MISO)

texts:
I have always been irritated from the fact that one of the biggest stumbling blocks that I encounter is determining a reference in digital IOs.
I mean my issue is that RX and TX is reference dependent. COPI/CIPO removes that uncertainty in cases where a controller is well defined. (PCIe, for instance)
Is there a good reason not to implement this scheme in other peripherals?


texts: Am I on the right path to solve this RLC-Circuit? (Need to find the voltage at the resistor)

texts:
I'm currently taking Physics II and I'm tasked to solve for the voltage $$U_R(t)$$ in this circuit.

It's driven by a current source $$I(t) = I_0*e^{i*\omega*t}$$ and I can neglect the switch on process.
I'm currently at the point of having the differential equation to solve this problem but I'm not entirely sure on how to solve it yet.

I wanted to ask if my thought process was correct so far and if I landed at the correct differential equation or am I on the completely wrong path?


texts: I've been making some coils with wires and I find out that sometimes they work and sometimes they don't work at all, the inside of those that don't work are some what more "silver-ish", more "metal-ish" like iron. While the coils that do work do look more thin like copper. Does the conductive material used for the coil matter? (If it does I'm -greatly- interested in why)


texts: What is the physics behind width of the duty cycle in Arduino?

texts: I was wondering if someone can tell me how Arduino changes the width of the duty cycle? How it produces an on-off pattern? I am looking for an explanation for modulation in this system.


texts: Relation or difference between Input clamp current and Sink current

texts: I want to take input from external peripherals to PIC micro-controller(PIC18F66K22) through buffer IC(74HC541). My problem is o/p of buffer source current is +/-35mA and i/p of PIC18F66K22 PORTF pin is 2mA. And another case input clamp current of PIC18F66K22 is +/-20mA. We may directly interface these two IC's? And in what way input clamp current and sink current related or differs?


texts: Understanding single sideband modulation and demodulation

texts:
I know this question has been asked a lot of times before but I cannot really understand how the message is transmitted in single sideband modulation.
See the following images taken from the book "Eletronic communication systems" by Kennedy :
Full AM modulation

DSB-SC

SSB-SC

Now the message is clearly visible in the first two diagrams, but not in the third one.

Doesn't the sideband modulated wave look like a regular sine wave from a generator?
Where is the message in sideband?
How exactly is the message recovered from the third diagram?

Please explain in TIME domain with diagram.
Please focus on conceptual treatment rather than individual techniques of modulation and demodulation.


texts: Pre-Made Cables & Headers for (Parallel Interface) GLCD's

texts:
Is it possible to buy Pre-Made cables & headers to suit GLCD's, the model Im using has a 20-Pin interface like the model in the image below.

If as I fear such a convience does not exist what do you use/have you found to be the neatest way to connect these?


texts: Is it possible to decrease the power dissipated in a winding with a constant braking torque?

texts:
I have a 4-quadrant current controller which regulates the braking current of a brushed DC motor with a high-inertia load to a constant level, but the motor winding cannot handle the current required to halt the load in the time I want.
I thought I could dissipate the energy elsewhere by regulating the braking current and letting it drain back into the supply where a DC link regulator is, but I was wrong: the only thing I would be doing, would be to charge up the inductor, and discharge it into the DC link regulator.
I have the feeling now that I can't decrease the power the winding itself dissipates for a given mechanical braking power, since I can clearly see the mechanical breaking power is the back-EMF (constant at a given time) times the current (constant because regulated at the desired braking torque), regardless of what I do with the current.
Could anyone confirm or suggest how I could achieve what I want electrically (except brake over a longer time)?


texts: What is the significance of 0V output from a regulated power supply?

texts:
I am mainly interested to know the application of 0V output from a lab power supply. Which linear regulator IC one can use to get 0V output?

Edit:The LT3080 datasheet says that it is adjustable to 0V. How is it useful?

As far as I know, the well-known linear regulator LM317 can output as low as 1.25V but nothing less. However, this page 0 – 24 Volt, 2 Amp Bench Top Power Supply shows a linear power supply circuit that uses LM317 which can output 0V. Is it true?


texts: Design rf trace antenna 433MHz + 315MHz on pcb

texts:
I'm a hobbyist and I'm designing a PCB in Eagle that include micro controller and RF receiver and transmitter, 2 modules of 433mhz and 2 of 315mhz,

I have a defined place on the PCB of 10x50 mm for the 433mhz antenna, and another 10x50mm for the 315mhz.

I searched the entire web and could not find a design,
I created a simple doodle of antenna (i have no experience in antenna design... and this might be horribly wrong)

So this question is for the experienced ones out there:

How should a 433mhz trace antenna look like in 10x50mm space?

How should a 315mhz trace antenna look like in 10x50mm space?

I uploaded a picture of what i got so far.

Thanks for the help!


texts: Statemachine as a separate module in VHDL?

texts:
I would like to create a state machine as a separate unit with multiple inputs and one output. The output will be the state.

The states are defined by a syntax similar to type states is (s1, s2, s3);

Now, how do I build the units ports. What should I assign to it. Is it std_logic_vector or is it "states" type?

If I set std_logic_vector it says that the types are different and you cannot asssign.

If I use "states" it says that it cannot find this type. (because states is defined in its arhitecture)


texts: Maximum Power Transfer in a Signal Chain

texts: I have a source signal generator with source resistance Rs, I want to buffer/amplify the signal before using it further. Do I need to match the input impedance of the amplifier to the source resistance as to maximize the power transferred or do I need to maximize the input impedance to have no voltage drop across the source resistance?


texts: Is this the best way to make a timer auto-off feature for a CPU fan?

texts:
This circuit is outside of a PC

simulate this circuit – Schematic created using CircuitLab
I want to make a fan that shuts off after a preset time depending on the capacitor value. The button restarts the timer. Is this the best way to do so?


texts: Why voltage regulators instead of voltage dividers for supplying power to loads?

texts:
I have to supply 80 Raspberry Pi's with power, so I began looking into it and found a power supply of 12V 20A (might not be enough current to supply 10 Pi's that typically draw 1.5A - 2A though).

This meant that I would need to drop 12V to 5V, which I was originally planning to do using resistors for a voltage divider. However with a bit of brief researching I found you should never use voltage dividers as a power supply to loads due to the power that needs to be dissipated.

So I discovered using a voltage regulator was the way to go, however what I don't understand is, if a schematic of a voltage regulator component shows it is comprised of many resistors and transistors wouldn't this suffer the exact same problems as a voltage divider? Wouldn't the resistors internally burn up due to the power dissipation?

Or is it due to the heat sink attached to the component, which would mean hypothetically if you could attach a heat sink to a resistor it'd be fine to use a voltage divider to supply a load?

The reason I ask is trying to work out the best way to efficiently and safely supply 5V at 1-2A to all 80 Pi's I'm aware a few computers is a smarter option however the project involves 80 Pi's and that'sthe way it must remain


texts: Rowley Crossworks STM32 Start from Reset

texts:
I am using an STM32F4 with the Rowley CrossStudio for ARM. It is not clear to me how to have the MCU start from int main() on reset (i.e. power up the device). I thought building it in release mode would have done this, but that seems not to be the case.

Looking online, I see some people saying that you somehow change the startup vector but this may prevent future debugging?

Is there a good way to accomplish this so that I can debug if I need to and run my program without the debugger on startup?

Thank you!


texts: How many LEDs can I connect to each attiny85 port?

texts:
I only learnt about the attiny85 microprocessor a few days ago, but I'm very amazed with its capabilities, so I would like to start making some toys with them. However since I'm very new at it, I have several questions.

For my first project, I would like to connect 10 LEDs of 2 different colours to it - 5 of one colour to one pin, and 5 of another colour to another pin. As the website I bought the LEDs from didn't mention the current it uses, is it safe to assume that it draws a typical 20 mA?

The user from this article did mention that his (or her) attiny IC burnt out after connecting 8 LEDs to it.

Hence I would like to know if connecting the LEDs in the manner I described earlier would work? I also do have the concern that the maximum output voltage of 5V is insufficient to power all the LEDs.

Thank you all in advanced!


texts: High Torque Brushless DC Motors in Small Package

texts:
I have a particular set of requirements that call for a relatively high stall torque for the space available (300 ozf-in for < 8cm length of motor). The motor would be operating at a relatively low speeds (max speed of motor can be between 10-100 rpms) at a torque of about 200 ozf-in. The diameterical space available is less than 3“.

Initially I looked at some brushed DC motors and while there are some that meet these particular set of criteria, there is not much choice in terms of that package size.

So I decided to look at some BLDC motors usually used by hobbyists but the stall torque, rated torque, or speed-torque curves are not published anywhere. The motors quote only speed characteristics and I have yet to find one that publishes speed-torque curves.

I was wondering what kind of torques I could expect from these motors and if it would be sufficient for my needs. Are there any alternatives to the hobbyist motors that also come in a small package size?

I was also wondering if these motors could be operated at the low speeds I need (100 rpm), due to the commutation of the coils in the BLDC motor. If so, what kind of adverse effects could be expected by running it at such low speeds (maybe even below 100 rpm)?

Thanks for your help.


texts: Can the saturation of an OPA influence its input?

texts:
I am working with an analogue processing circuit, finishing with 2 non-inverting OPA one after the other.

To characterise the noise produced by the circuit, I wanted to add a third non-inverting OPA at the end of the circuit, in order to amplify x10.

Since the circuit is made to amplify just before saturation, I was wondering if the saturation of the third OPA could have an action on its input (i.e. does the measure after the second OPA will be the same with or without the third OPA following it).

As the third OPA has an infinite input impedance and that we are in a non-inverting sketch, I think that it won't change anything, but I am not sure about it.


texts:
I have a USB wall charger with this text on it:

INPUT: 100-240V 50/60Hz 0.5A
OUTPUT: 5.2VDC 2.0A 10.4W

I'm building a circuit I want to power via USB and I calculated it would sink 500mA from VCC. Can I use this charger for it? Will it force the current to be 2A and fry my circuit? Does "OUTPUT 2A" mean "2A source" or "2A max sink"?
Also, if it does force the current, how can I regulate it in a nice and cheap way? Do I have to fuse/polyswitch it?


texts: My values for this DC block and level shifter, part of an amplifier, are incorrect. I must be missing a key concept

texts:
I am trying to find the correct component values for a leg of an amplifier. There will be non-inverting amplifiers attached to From_First_Stage_Out and To_Second_Stage_In. This part of the circuits needs to:

block the DC offset from the first op amp
shift the center of the signal from 0V to 0.625V so that the signal range changes from [-0.3V,0.3V] to [0V,1.25V].

Here is the diagram:

I know that the filter comprised of C3 and R4 blocks noise from the +9V supply to R5. I am told that the "ideal" low pass cutoff frequency of this filter is 60Hz, so, knowing the value of C3, I calculated R4 to be\$\ R4 = \frac{1}{2(60Hz)(1μF)}\$ ≈ 2.652 kΩ.

R4 and R5 make a voltage divider. I am also told that since we're blocking the DC offset coming from the first op amp, the only offset remaining will come from the second op amp, which will have a gain of 100. Specifically, my lab manual says, "The voltage divider consisting of R4 and R5 must, when followed by a gain of approximately × 100, yield the required DC output of 0.625 V; i.e. the divider should yield a voltage of approximately 6.25 mV." So \$\ \frac{R4}{R4+R5}\ = \frac{1}{100}\$, which means R5 ≈ 263 kΩ.

Apparently, R4 ≈ 700Ω and R5 ≈ 1 MΩ. I realize that \$\ \frac{R4}{R4+R5}\ = \frac{1}{100}\$ is likely incorrect. I want Vout = 6.25mV so that in the second amplifier the output is 0.625V. I do not know, however, what Vin is. Since the max input before the level shifting is 0.3V, should I use this value? Or do I use 1.25V, the max input after the shifting? This comes down to me not knowing exactly which part of this circuit is going the shifting.

Clearly, I have something totally wrong here. What am I missing?

Thank you in advance.


texts: How can I turn an LED on only at 24 V ± 1 V?

texts:
Is it possible to make a circuit so an LED turns on at a specific voltage?
My requirement is to indicate whether 24 VDC is available at the pcb or not (used as a power supply indication.)
I want the LED to light up at precisely 24V (± 1V tolerance) and I tried with a voltage divider circuit but I can only limit at lower side(5,12,21 V) not at the higher. Once the 24V drop across the LED it starts to glow even 28V as an input voltage.


texts: How do I measure the amount of energy consumed by a device?

texts: I am considering installing solar panels to power a shed. The shed will need a lighting, a fan, a heater, and some other appliances. How do I measure how many kilowatt hours of energy is consumed by a specific device over a certain period of time? I want to do this to get an estimate of just how many kilowatt hours of energy the solar panels will need to generate.


texts:
I went through a previous Industrial PC Motherboard design in my company where Ritchtek RT9045 was used for DDR4 design. it's clearly recommended tat this device is ideal for DDRII/DDRIII in the features.
I'm designing a PC motherboard which uses Intel Tiger Lake UP3 CPU. and I was wondering if I can use this device for my DDR4 SODIMMs.
what are the parameters that I should consider that could affect my choice?


texts: GPIO using StellarisWare with LM4F120H5QR LaunchPad. SW2 not working as expected

texts:
I am trying to figure out how to properly use StellarisWare, the built in ROM calls, for GPIO. The Stellaris LaunchPad has two switches (SW1, SW2) and three LEDs (RED, GREEN, BLUE).

I wrote a little program that reads the switches and turns on the related LEDs when I push them. Everything works as expected:

SW1 lights the green LED;
SW2 lights the blue LED;
SW1 & 2 simultaneously light the red LED.

This is the code:

#include "driverlib/gpio.c"
#include "driverlib/rom.h"
#include "driverlib/sysctl.h"

#include <stdint.h>

#define LED_RED   GPIO_PIN_1
#define LED_GREEN GPIO_PIN_3
#define LED_BLUE  GPIO_PIN_2

#define SW1 GPIO_PIN_4
#define SW2 GPIO_PIN_0

#define GPIO_PORTF_LOCK_R       (*((volatile unsigned long *)0x40025520))
#define GPIO_PORTF_CR_R         (*((volatile unsigned long *)0x40025524))
#define GPIO_PORTF_DEN_R        (*((volatile unsigned long *)0x4002551C))

int main() {

    // Enable GPIO port
    ROM_SysCtlPeripheralEnable( SYSCTL_PERIPH_GPIOF );

    // Enable LED pins for output
    ROM_GPIOPinTypeGPIOOutput( GPIO_PORTF_BASE , LED_RED | LED_GREEN | LED_BLUE );

    // Enable switch pins for input
    ROM_GPIOPinTypeGPIOInput( GPIO_PORTF_BASE , SW1 | SW2 );

    // Enable switch pins pull up.
    ROM_GPIOPadConfigSet( GPIO_PORTF_BASE , SW1 | SW2 , GPIO_STRENGTH_2MA , GPIO_PIN_TYPE_STD_WPU );

// GPIO Lock (GPIOLOCK)
GPIO_PORTF_LOCK_R = 0x4C4F434BU; // unlock the lock register
// GPIO Commit (GPIOCR)
GPIO_PORTF_CR_R = 0xFF; // enable commit for PORT F
// GPIO Digital Enable (GPIODEN)
GPIO_PORTF_DEN_R = 0xFFU; // enable digital on all pins in PORTF

    while ( 1 ) {
        switch( ROM_GPIOPinRead( GPIO_PORTF_BASE , SW1 | SW2 ) ^ ( SW1 | SW2 ) ) {
            case SW1:
                ROM_GPIOPinWrite( GPIO_PORTF_BASE , LED_RED | LED_GREEN | LED_BLUE , LED_GREEN );
                break;
            case SW2:
                ROM_GPIOPinWrite( GPIO_PORTF_BASE , LED_RED | LED_GREEN | LED_BLUE , LED_BLUE  );
                break;
            case SW1 | SW2:
                ROM_GPIOPinWrite( GPIO_PORTF_BASE , LED_RED | LED_GREEN | LED_BLUE , LED_RED   );
                break;
            default:
                ROM_GPIOPinWrite( GPIO_PORTF_BASE , LED_RED | LED_GREEN | LED_BLUE , 0 );
                break;
        }
    }
}

However, when I skip the six lines starting at // GPIO Lock (GPIOLOCK), the program starts to act in an unexpected way: SW2 is always read low, wheras SW1 is working as expected!

I would expect that there is a StellarisWare ROM call that does "the hard" stuff, but I can't seem to find the right call. So the question is: What (StellarisWare ROM call) am I overlooking here?

®Stellaris LM4F120H5QR Microcontroller
Stellaris® Peripheral Driver Library


texts: If I use twisted pair cable for I2C, should I twist SDA with SCL or both with the ground/power?

texts:
I need to design about 1 meter cable for I2C communication. It contains 4 wires, SDA, SCL, ground and power. I plan to use the shielded cable with the shield grounded at one end only.
It looks reasonable to use the twisted pair cable (that has 2 twisted pairs inside.) Which should be twisted with which? I initially assumed that SDA and SCL, the signal wires, should be twisted together (like in USB.)
However, I found on the web random posts that the signal wires should be twisted one with the ground, another with the power instead. How much of this is correct?


texts: Questions about Interfacing ADC: ADS5463 with FPGA

texts:
Im beginner FPGA Designer.

I need to interface the ADC component: ADS5463.
datasheet: http://www.ti.com/lit/ds/symlink/ads5463.pdf
with a FPGA (lattice ecp3).

I need suggestions how to start implementig it.
From my understanding all I need to do is State Machine based on the timing table and graph given by the datasheet:

and to understand the inputs & outputs of this ADC, espcially the digital signals: (clk, dry, d[11:0], ovr)

I wrote a body for the verilog code.. but still think how to really write the logic:

    module top(
    input clk,                       //clock input = 250MHz
    input rst,
    output reg dry,              //DRY
    output reg ovr,              //OVR
    output reg [11:0] d_o;       //D[11:0]
    );

    reg [5:0] cs, ns;

    localparam  idle        = 6'b000001,
                start       = 6'b000010,
                busy        = 6'b000100,
                read_middle = 6'b001000,
                read_end    = 6'b010000,
                done        = 6'b100000;

//clock input = 250MHz -> Ts=1/fs=4ns
    localparam  t_aperture = 200 ,   //200ps
                latency    = 8   ,   //3.5 input clock cycles -> 8 rising+falling edges of clock
                t_dry      = 1600,   //950-1600ps CLK to DRY delay
                t_data     = 2100,   //750-2100ps CLK to DATA/OVR delay
                t_skew     = 650 ;   //-350-650ps: t_data-t_dry: DATA to DRY skew.

        always @(posedge clk or posedge rst)
        if (rst) begin
            cs <= idle;
        end else begin
            cs <= ns;
        end

    always @(posedge clk or posedge rst)
        if (rst) begin
            ns = idle;
            dry = 1'b0;
            ovr   = 1'b0;
            d_o   = 12'b000000000000;

        end else begin
            case (curr_state)
                idle:

                start:

                busy:

                read_middle:

                read_end:

                done:

endmodule

My Questions:

what is my job in this kind of design? I need to write onyl state maching based on timing table and connect all the inputs/outputs to the FPGA andd I'll see the right results?
based on the datasheet, on which signals I should have control of? for example DRY is signal which the ADC produce and I should use in my code or I should control it logic levels in my code => take the CLK divide it by 2 and delay it to the middle of the clock?
any Idea how I should build my state machine? seems like I need 3-4 states here: IDLE, BUSY, DONE. any idead how i create 200ps delay with 150-250MHz clk? i thought about just make 1 clk cycle of delay and it will do just fine.. maybe a bit slower that what the datasheet recommends but safe and works.
I would be very glad for any good explanation or piece of code for how to start to do it.

Thanks!!


texts: Altera DE2 interfacing with analog sensor

texts:
Can Altera GPIO pins read the analog output of a light sensor? The light sensor output is analog and I want the Altera to turn an LED on whenever the signal of the sensor is greater than some specific value.

Can I do that directly, or do I have to connect the output of the sensor to an ADC? How would I go about that?


texts:
If the following is true:
"When forward biased current in a diode is due to flow of majority carriers and in reverse biased it us due to minority carriers also called leakage current".

I relate this concept to the transistor (BJT) in that current flow can be explained as majority carriers are injected into the base from emitter, these  essentially become minority carriers in base and flow to the collector crossing the reversed bias junction.

So the Question basically is :

Could we say that current in the transistor is due the flow of both majority carriers(from emitter to base) and minority carriers(from base to collector)  in the same direction?


texts: What is the right way to measure K on an inductor with three coils?

texts:
I have an inductor which has three coils, L1, L2, L3.
In normal use L2 and L3 are connected in series, and resonated with a capacitor.
L1 would then drive the tank circuit.
In Spice, I need the coupling factor "K" which is found by measuring L1 with a second winding open and shorted, K=sqrt(1-(L2s/L2o))
Is it more accurate to take the K measurement for each winding independently against the others, or should I just series connect L2 and L3 and measure a single K for L1 vs the series combination of L2 and L3?


texts: Where does the additional capacitance come from ? (Pull-up delay)

texts:
I am using a couple of daisy-chained ADG1414 switches, that use a serial input of the switch state.
Data is clocked into the first chip in the chain into an SDI pin, and clocked out via an open-drain SDO pin to the subsequent chips.
I am pulling up the SDO with a 680 Ohm resistor to 3.3 V. The datasheet specifies 4 pF of Open-Drain Capacitance and 4 pF of SDI input capacitance.
I thus estimate a conservative time constant of 10 pF * 680 Ohm = 6.8 ns.
In practise, I measure a time constant of ~18 ns on the board, implying a node capacitance on the order of 26 pF. This slows down my serial input by a factor of 2 to 3. Of course I could use smaller pull-ups but I would prefer not to.
Where is that additional ~18 pF of parasitic capacitance located ? The screenshot shows an example SDI-to-SDO connection. The trace is 0.254 mm wide and ~9 mm long. There is no GND plane under the trace; the next plane is 1.6 mm away. The chip on the right is the SDO side.

One guess would be of course the stray capacitance to the neighboring conductors. I crudely estimated this as a plate capacitor with d =0.254 mm and A = 35µm * 9 mm. The result is way sub-pF. This sounds too low, so I wonder what better way there is to estimate this stray capacitance.


texts: I am using a mini-360 dc-dc converter with arduino pro mini, so will mini-360 discharge battery without any load? Is it correct to use power switch as on image?


texts: I study computer engineering and I read Hennessy's book about Computer Organization where it's described how the microprocessor does pipelining and that the microproceossor has on-chip cache, as much as 8 MB on-chip cache in a modern microprocessor such as AMD's Opteron. Is that on-chip cache made from SRAM or what are the physical characteristics of a modern registry file and its 2 caches, instruction and memory? Is it the same material in the L1, L2 and L3 caches?


texts: What is a Redundancy Buffer Power Supply?

texts: I was browsing DIN Rail power supplies by output voltage and noticed Redundancy Buffer Power Supplies for very cheap relative to normal supplies. It looks like a normal supply is still needed and these units are for when extra reliability is needed. That said, I'm still unclear exactly what for and when these units are used.


texts: How does 13 connections control a simple LCD with 34 segments?

texts:
Inside my digital scales I find a 7-segment style LCD capable of displaying "-88:8.8" plus 3 symbols indicating Kg, Lb or St. This adds up to 34 individual segments, assuming the colon is a single symbol.

The LCD is connected via one of those rubber strips to the circuit board, which has 13 contact points.

I can not see any circuitry on the LCD.

How does this work? Most of the LCDs I have seen earlier seems to have individual connections to each segment.

Is there perhaps some sequencing of segment groups going on, where each group has a separate ground?


texts: Is there any Laplace transform whose ROC contain a pole?

texts: While I was reading "Signals& Systems" by Oppenheim, I read that "For rational Laplace transforms,  the ROC does not contain any poles". So, I was wondering is there any non-rational Laplace transforms that contain poles.


texts: IO port register whose address is software defined (x86)

texts:
I want to do something that I assume must be fairly common in digital logic/bus design. It’s for a new expansion card for an old 8088-based computer. This isn’t some kind of college homework project.
I want to create an 8-bit R/W IO port register (port A) whose address is software defined. By which I mean its address can be software defined by a write to a 16-bit IO port register (port B) – let’s say port B is at 100h, just for example.
So if I write 60h to IO address 100h (port B), then subsequent IO reads and writes to 60h are reading or writing the contents of port A.
I was thinking I could use some 74x373/573s to create IO port registers A and B.
I’d take the outputs from port B to the P inputs of a 2x 74x688 comparators, with the Q inputs coming from the latched address lines.
If an address on A0..15 matches the value in port B (100h in my example), the comparator outputs would enable a 74x363 connected as my IO port A.
That means that a read or write to IO address (60h) defined by Port B would read or write to register IO port A. I know I’d have to use IO/M-, RD- and WR- appropriately.
I drafted a schematic - does this look right? The port B address is decoded on the left (I know I have to take care of the higher-order address lines).
I'll have latched address lines going into the two comparators.
My RD- and WR- are IO Read and Write, active low.
I thought I'd need a bus transceiver like a HC245 - but isn't the HC373 good enough on its own??


texts: Soft power off with delay after flipping physical switch

texts:
I have a microPC (the Jetson Nano, 10 W) that cannot handle a sudden power loss. However, the casing I need to design it for only has a latching switch for powering on and off. I need to design a circuit that will facilitate the powering of Jetson Nano (along with some power converters) and will keep powering it for about 30 seconds when the user switches off the system with the switch. This way the Nano will be able to read the switch and shut down in time.
To read the battery status I will be using a ATmega328PB and a small 1inch OLED. This MCU will come out of low power mode by a momentary "check battery" button. The system will be using a 99 Wh battery so a few milliamps of power are no problem. Is the schematic below a viable solution? Can I use analog components to completely power down the system?

simulate this circuit – Schematic created using CircuitLab
(battery display and button are not shown for clarity)


texts: How to remove DC offset (and make average DC value 0V) from ADS1261 square wave AC-excitation circuit

texts:
I am attempting to remove the DC offset from the 1 kHz, ± 2.5 V, AC square wave output pins of an ADS1261 (http://www.ti.com/lit/ds/symlink/ads1261.pdf). However, when measured on the oscilloscope (and modelled in LTSpice), the average DC value is approximately 2 mV.

I have modelled a passive RC high pass filter in LTSpice (similar to Changing a Signal's DC Offset), however, I have found that instead of maintaining the ± 2.5 V and removing the offset, I get 0 - 5 V output instead.

How can I remove the DC offset/average while maintaining the ± 2.5 V square wave?

Circuit:

Result with C1 as 15 nF

Result with C1 as 100 uF