texts:
I am trying to correctly implement a circuit context for the e2v MiCS line of gas sensors (for example MiCS-5525). Reading the FAQ from the manufacturer they make this statement:

  HOW STABLE IS A SEMICONDUCTOR  GAS SENSOR WITH TIME?

  Above a certain
  operating  temperature, the heater  resistance will slowly increase
  with time. This is a known  phenomenon that can be easily compensated
  with an  appropriate circuitry.  Long-term tests have shown that at 40
  mW, no drift is  measurable over 6000 hours. At 80 mW, the heater
  resistance can rise up to 30%. By powering the sensor with  an
  appropriate series resistance on the heater, this  resistance does not
  impact the sensor power by more than  2% over the same period, which
  is sufficient for most  applications. More sophisticated “constant
  power” circuitry  can be used to fully eliminate this effect.

I don't understand why a series resistor for the heater is necessary or would help at all to combat the phenomenon in question. For the MiCS-5525 would it not be sound to simply apply 2.4V from a voltage regulator across the heater terminals of the device? I also don't know quite understand what they are talking about when they suggest a "constant power" circuit as an alternative, how would one go about designing such a thing?


texts: Driving EL wire with Supertex HV850 family drivers

texts:
I was considering driving EL wire with Supertex'es ICs or some equivalent ICs from another manufacturer. The ICs are designed to drive EL panels not EL wire. Would this still work?

Supertex'es ICs are rated for "lamp sizes" up to 42 square inch. My wire is 2.3 mm in diameter and 20 meters long. I'm going to assume 2.3 mm is the diameter including the outer protective sleeve and the actual diameter is probably somewhere around 2 mm. Looking up the formula for a cylinder's surface area I determined that my EL wire has surface area of about 2513 cm² (about 390 square inch). That's way too much for those ICs.

According to this calculation I could drive up to 2 meters of EL wire with these ICs. But is this calculation applicable to EL wire at all?


texts: Purely Capacitive AC - voltage and current relationship

texts:
Studying electronics, capacitors in AC circuits currently. Can not understand two formula's.

I see it stated as fact: "In purely capacitive AC circuit Current leads Voltage by 90 degrees." I understand this relationship when viewing Waveform 90 degree phase difference Current leads Voltage.

I can't however find any example with circuit values to prove this is so.

I have two formula that prove this is so.

i = dq / dt

i = C * (dv / dt)

Can anybody show me how this works with actual circuit values?
If I say (random example) AC 10V 200Hz with 0.0005F capacitor

Then i = dq / dt = ?? / ??

or

i = C * (dv / dt) = ? * ?? / ??

Example with number please for above circuit?

I am so confused I don't know if I just take "Current leads Voltage 90 degrees" at face value, but can it be proven with actual numbers? Maybe there is no example because there is no circuit without resistance or truly purely capacitive? Maybe it is just a theory not real world formula?


texts: Inverse Laplace Transform of an LTI with complex roots and s + real term in the numerator

texts:
I have this transfer function

$$H(s)=\frac{10(s+300)}{s^2+20s+50000}$$

and want to find the steady state response to an input of

$$x(t)=2\cos(2\pi30t+0.7)u(t)$$

But I am struggling to do anything with the transfer function.

I am familiar when I can get it to the form

$$\mathcal{L}\left[Ae^{-at}\cos{{\omega}t}+Be^{-at}\sin{{\omega}t}\right] = \frac{A(s+a) + B\omega}{(s+a)^2+\omega^2}$$

But clearly the \$a\$ terms will not match in the numerator and denominator. What do I do to find this response?

I have succesfully found \$h(t)\$ and I know it to be correct, but I'd like to know the steady state response. How is that determined?


texts: Running multiple 4-wire bipolar stepper motors without drivers etc

texts:
I need to use about 120 motors for an arts project. My budget is limited, as are my skills.
I need linear motion. I have found well-priced stepper units driving lead screw and nuts at sensible prices.
I only need simple up and down motion to the limit of travel.
I propose using limit switches at either end for this.
I have seen videos showing stepper units being run from a 12 volt transformer using a capacitor, which allows forward and reverse operation.
My question is -
Is the power output using this method sufficient to drive the lead screws effectively?
The motors are 4-9 volt or 12 volt depending on seller. The following data is for conventional use with a driver and controller:

800 mA per phase.
Bipolar 4 wire
3 mm thread diameter : thread rod pitch +-0.5 mm
Pull out thrust 500 gm

Any help/advice will be much appreciated.

Updates:
Hi Schnedan
Whilst I have good electro-mechanical skills, I have no knowledge of coding hence this is an attractive option.
All relays are closely spaced and fed by heavy duty bus bars.
All start in fully down position - lower limit switch to be overridden by low coil current relay. Central control by a pair of 81 LED sequential programmers. NE555 and CD4017 creating a wave action. Return to lower position centrally controlled for all units simultaneously, via heavy duty relay. Apologies for poor info and would welcome any suggestions.

Hi Brian
Good suggestion, but there's a long lead time from order to delivery of units from China (about 6 weeks) so would appreciate any top tips.
Hi Graham
Good suggestion but none available with built in lead screw , captive nut , guide rails and chassis .Steppers however are plentiful and affordable as a complete unit - see e bay .
Thanks for Arduino suggestion - I want and need to embrace this but at the moment need to stay within my skill set .
Best Tony
Hi Chris
Thanks for your observations.
I have a number of constraints

Money - this is a big project for me with a very tight budget.
The units I’ve sourced cost £7 each and are very well engineered and have sufficient travel for my needs.

2.Time - I’m single handed - modifying 120 units with DC motors ( which I may have to do if plan A doesn’t work ), will be time consuming and add significant extra cost which is a problem.
3.My “driver “which is a pair of 81 LED chaser Units, using NE555 and CD4017 chips is cheap and simple to build , and I’m planning to use a”relay based enabling system as you suggest .
4.I have good electro mechanical skills but no knowledge at all of Arduino and code etc . I don’t have the time for a new and probably steep learning curve so I want to stick with what I’m good at much as I would love to expand my skill base .
5.The “wave” I want needs to be very slow with a long travel time .Each unit has a three second time for the full range of movement  of 80 mm.The units will trigger at 0.25 second intervals giving a total time for the wave motion of around about 33 seconds. Broadly my goal.
So thanks again for your input .
Best Tony
Hi Brian
Ive taken your advice and ordered a dozen units to play around with to see if my  ideas using the AC plus capacitor will work or if I need to go to plan B  converting all 120 units to DC motors - a lot of work . I acknowledge that DC is easier particularly from the point of managing power requirements but the scheme is a trade  off .
I’ll let you know how I get on although it will be 6 weeks before I receive the units to play with .
Best
Tony


texts: UART DMA RX buffer queue are being shifted on every power on- off

texts: There is a communication between TFT NX8048p070-011r and my STM3F4 over UART. TFT sends 8byte data continuously and MCU receives by using circular DMA. I apply a parser to those data in Txclptcallback. When I toggle the RST pin Rx buffer contents are shifting for ex.  if Rx buffer is [0,1,2,3,4,5,6,7], when RST toggling occurs buffer comes like [6,7,0,1,2,3,4,5]. This problem occurs randomly. Baudrate:115200. There is no problem at transmitting. What will I do now ?


texts:
I am answering this question as shown in the image.

I had no trouble deriving \$\frac{V_{out}}{V_{in}}\$ in the first question(answer is \$\frac{j\omega L}{R + j\omega L}\$

I also had no trouble with doing part b). I just plugged in \$\omega\$=0 into the equation derived in a), and got zero.

I am having trouble with c). When I plug in \$\omega\$=0 into the equation derived, I get \$\frac{V_{out}}{V_{in}}=0\$, and thus the angle of \$\frac{V_{out}}{V_{in}}\$ is zero... However, this is wrong. I then tried to multiply the equation derived by the complex conjugate, to which I then separated the real and imaginary terms, however, I still got the  \$\frac{V_{out}}{V_{in}}\$ is 0... I have found that the angle of \$\frac{V_{out}}{V_{in}}\$ when \$\omega\$=0 is 90o, but I do not understand how this is, because when I substitute this value in the equation it does not make any sense to me how the angle is 90o...

Thank you.

PS. When multiplying the equation by the complex conjugate, I got:

$$\frac{\omega^2 L^2}{R^2 + \omega^2 L^2}+j\frac{\omega RL}{R^2 + \omega^2 L^2}$$


texts:
I have a Mackie MR8 MK2 powered studio monitor that recently started making a horrendously loud humming and clicking noise (I mean LOUD, as in cover your ears).  Being just out of warranty, I decided to open it up.

I'm not an electrical engineer, so I'm not sure how to identify a blown capacitor, but I've attached a picture of one I suspect to be bad.  It is slightly bulged at the top, and a small bead of a brown rusty material is right in the center.

My questions:

Is this capacitor suspect judging from the picture?
What's the probability that this cap was damaged due to another component failure?
Taking my symptoms into account, would it be advisable to replace the power amp chips as well.
Are there any other commonly blown components I should replace/test as a precaution.  I don't want to replace the big capacitor just to have it blow again.

I realize answers my not apply directly to my model of preamp, but I'm just asking in general what would be good practice without having to test every single component.  I have limited access to lab equipment.


texts: I have an SMPS which takes input of 220-240V, 50Hz single phase AC supply and gives an output of constant 12V DC.Its current rating is 20A. I needed constant 24V for a PMDC motor which works on about 2A current. So, I connected the outputs of 2 SMPS in series. It showed 24V but when I connected the motor across it wasn't supplying the motor any power. In the above case I was connecting both the SMPS in same phase of the main supply. Then I connected the two SMPS in different phases(just suppose one SMPS in R-phase and other in Y-phase). Now the circuit was working and supplying power to the motor. I know the results but I don't know the physics behind it. Can someone explain?


texts: Is it possible to program the nRF24LE1 with an AVRISP mkII? It has an Intel 8051, and I've noticed that AVR also supports this instruction set, so perhaps they already have a compiler in AVR Studio? Otherwise how would I go about integrating sdcc in? Otherwise how could I program the nRF24LE1?


texts:
I am trying to compile a design in modelsim (which I am new to) and I keep getting the following error for one of the files...

(vcom-1491) Empty source files.

I have looked everywhere for a solution and can't find an answer. As far a can see the file is not being compiled into the work directory but I have no idea why.


texts: Can I Simulate a SMPS Compensator on Matlab/Simulink

texts: I've designed a type 3 compensator for a full bridge dc-dc converter, I just want to be sure about its stability and want to check its bode plots, I have a open loop model, I can apply pi control on it but the real circuit I have has an analog control and I need to check its stability is there any way that I can simulate a type 3 compensator on matlab/simulink environment.


texts:
In signals, we learn that the energy of a signal is the integral of its square.

E.g.

\$E=\int_{-\infty}^\infty x^2(t) dt\$

We know that integrals are the areas under the function in a graph. But what is the graphical representation of the energy of a signal? Or is the integral of a square just a purely algebraic thing?

Thanks


texts: Adding multiple transistors to increase the output power of an amplifier

texts: I have a Sony amplifier 500 watts I like to increase the out put power to 1000 watts if I add more transistors will it work. How practical is this can this be done. Thank you


texts:
I have implemented an ASK modulator and demodulator pair. The modulator works fine, but the demodulator is giving a vague output. Below is the image of the whole circuit and the simulation output.

In the below output, blue is the carrier of 27 MHz, red is the digital wave of 150 KHz, green is the ASK output and yellow is the de modulator output.

I am not much of an electronics guy, so not good in tuning the circuit. Please help me achieve the desired output so that the yellow wave resembles the red digital wave.

EDIT 1 -

After trying many combinations of R11 and C2 values, finally i got one that is sending considerable voltage into demodulator. The output is still a straight line but its non zero this time.

Here blue is the volatage after the R11 and yellow is output from demodulator.


texts:
Reading a lot, I have found nothing about calibration for the MCP9808. I have read the datasheet and understand that the chip converts the temperature to Celsius. The given accuracy in the datsheet is typically -+0.25/0.5 Celsius. And my question to you is if you think this is enough for a normal temperature sensing application ( weather sensing,room sensing and etc.. ?) I mean how do I know how accurate or how precise the sensor is? So far, I have come forth to that a calibration isn't needed, but I think it would be a "timesaver" for everyone if someone answered this question properly and maybe open a discussion if possible.

Regards, junior Engineer


texts: Question on dsPIC33F PWM Period and Duty Cycle Calculation

texts:
On the Microchip dsPIC33F family, the PWM period PTPER is calculated as:

  PTPER = (FCY/FPWM)*(PTMR Prescaler Value) - 1

where PTMR is the input clock to the PWM and FCY = Fosc/2, FCY being the instruction cycle frequency and Fosc the main clock frequency. It is specified that the input clock to PTMR is Fosc/4 (ref. doc: DS70165D-page 178).
Does this mean that the period is calculated in instruction cycle clock ticks, or twice the instruction cycle clock ticks? Does this information relate to why multiply PTPER by 2 in the following line of code (taken from Microchip Application Note AN957):

PDC1 = (int)(((long)(PTPER*2)*(long)DutyCycle) >> 15); // why multiply PTPER by 2?
PDC2 = PDC1;                      // PDCx is the duty cycle register for PWMx channel
PDC3 = PDC2;                      // x = 1,2,3

In my understanding, the factor of 2 shouldn't be there. A more complete version of this code was posted yesterday at this forum:
Help understanding the code


texts: What are the failure mechanisms in an integrated circuit?

texts:
Context

I've always tried to design my circuits for chips to be well within their absolute maximum ratings. However understanding the failure mechanisms is vital to be able to debug a chip when something does go wrong (usually I end up trying with another chip which costs time).

Question

Hence my question: what are the most common failure mechanisms due to incorrect use (i.e. input/output voltages and currents) of integrated circuits? Details and diagrams are a big plus for this complex question, the ideal answer would link most common families of inputs/outputs (CMOS etc.) and bad uses (reverse voltage, overcurrent...) to failure effects.

Example

This is a general question, but what triggered it is that in order to protect against negative input voltages of an asymmetrically powered device it seems that current limiting resistors are enough (I had parallel schottkies before). Does that mean there is no such thing like voltage failure, every failure is current-related (to some extent)? How exactly?


texts: Outputting 10V from 7 ports, low current

texts:
I'm working on a school project with a lighting unit that has seven inputs that read between 0-10VDC. I need some sort of microcontroller, relatively inexpensive, that can be programmed to output what I want to these seven inputs with that voltage range. Would something like an Arduino Mega be sufficient, with voltage doublers to get from 5V to 10V, to send those voltage outputs to our lighting unit? I realize I may also have to use something to convert the PWM signal closer to DC, suggestions on that would also help :)

Any answers are much appreciated!


texts: How to obtain a dual power supply ±2.5V from a battery for a portable system?

texts:
I’m working on a portable system that uses a microcontroller and an analog/digital converter. I want use this ADC in dual power supply mode so I need a ±2.5V .

In my previous project, the system was wire-powered by USB and made use of an isolated dual output DC/DC converter which provides a ±3.3V, so with two LDO positive and negative regulator I obtained the ±2.5V.

Now I want to transfer the project in a portable contest and I need to make some changes to reduce the system size. For this reason, I can’t use the previous DC/DC converter type yet cause they are too big for my intent.

I tried to find on the web distributors some IC that provide a dual ±2.5V power supply from a single positive source, but I found one or two solutions that don’t satisfy me at all. Furthermore, these IC use a charge pump that create on the output a very high ripple, but I think that if I use two LDO regulator with high PSRR the problem is in part solved.

So, my questions for you are:

Do you have any suggestion to obtain a dual power supply ±2.5V from a battery, with the noise as low as possible?
Do you know some good IC that made this?

Thanks in advance.


texts: How many volts is needed to power a coil

texts:
I recently encountered and was trying to troubleshoot a device that's not working properly. In tracing the functionally of the device, I isolated the issue with a coil that does not activate.
Unfortunately, there's no diagram and/or any useful information to follow. I just have a picture of the coil, and at this point, I'm just trying to figure out how many volts would I need to directly power this coil.
I did try to apply 11 (and 13) DC volts, and the coil did not budge. I tested and there is continuity across the coil leads.
At this point, I'm looking for the correct way to power this coil.


texts: An Integrator Reset Circuit not working properly

texts:
I am trying to integrate the output of a Rogowski coil , with an inverting integrator with a reset circuit. I want to have the voltage level 0V during the off time of my switch, however after reset interval, the output voltage does not stay at zero and drops to some negative value.
During the entire time after the reset event, the input is zero, so there is no apparent source for this negative value.. Can someone please answer why does this happen?
EDIT 1:As per the answer by Spehro Pehfany, the problem indeed was the charge injection due to the JFET. However, I do not get the same problem with a non-inverting integrator, what might be the reason for that. I used the same device there too.


texts: How can you delay your fsm to stay in one of the state for about lets say 5 clock cycle?

texts:
If I want to delay my FSM to stay in a state for 5 cycle how could I do that?
I suppose I should use a counter but what is the VHDL code how could I use a counter inside the process statement.

Sorry if the question is simple I am learning VHDL coding.

I am using this coding, but it is not compiling :

library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_arith.all;
use ieee.std_logic_unsigned.all;
use ieee.numeric_std.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;
  signal count              : 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, count, pr_state, done_H)
  begin
    case pr_state is

      when s0 =>
        if (start = '1') then
          nx_state <= s1;
        else nx_state <= s0;
        end if;

      when s1 =>
        count <= count + 1;
        if (count = 5) then
          nx_state <= s2;
          count    <= "000";
        else
          nx_state <= s2;

        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:
I need help naming a type of rotary switch. (If it exists.)

I am looking for a rotary switch with no stopping point, so it would go around and around when turned, repeating each position infinitely.

Do these exist? If so, what are they called so I know what to look for when I try and buy one online?

Thanks in advance!


texts:
I'm using STM32 F7 46 (reference manual) and I'm a bit confused about ADC and reference voltage (VREF).

If I connect 2.5V to the VREF and 3.3 to AVDD, then what is the range of ADC measurement?

Is ADC range from 0V to 2.5V?
Or is 2.5V used to calibrate ADC reference (AVDD) and then range will be from 0V to 3.3V (=calibrated AVDD)?

I know that on AVR, (1) is correct, but I'm confused about STM32.


texts: Phase voltage in impedance grounded vs solidly grounded system during ground fault

texts:
Why does a phase-ground fault in an impedance grounded 3-phase system lead to variation of voltage in healthy phases but this variation doesn’t happen in solidly grounded systems?
I was thinking about using the idea of a neutral shift to explain it but turns out their both connected to ground so I see the neutral won’t float in either case so I can’t use that to explain it. Unless I’m missing something?


texts: Connecting the protective ground of a 3 phase AC motor

texts:
I am wondering how can I connect the protective earth of my 3 phase AC motor?
Here is the background of how my connections are:
I am using 3 phase with a neutral point from the mains which goes to  wye-wye transformers. The stepped down voltage is then fed into a 3 phase diode bridge rectifier, which is then fed into a 3 phase MOSFET bridge inverter. Now I want to connect the inverter output to my 3 phase motor, but I am not sure where should I connect the protective earth of the motor?


texts: What is the function of this choke-like transformer on the PCB side of this RJ45 jack+magnetics connector?

texts: I came across this ethernet jack+magnetics connector the other day and was wondering what the transformer on the PCB side was for. I thought it looked like a choke, but there is a centre tap running through the middle and the choke is usually on the network side. Can anyone explain what it is?


texts: Wiring a Logitech extreme 3D pro joystick for Xbox adaptive controller

texts:
The joystick only allows direction movement when connected to the Xbox adaptive controller, which doesn’t help when I have 1 hand and 17 buttons to connect.
There are only 10 buttons of the joystick that I need to enable through a mono aux cord to each individual button.
I've opened it up, cut the original harness that had circuits attached to the logic board, and I've cut up the tracks connecting everything together.
I'd really like to figure out how to connect the 2 channel Oni cords I got from Walmart since I’m able to shorten the diameter of the cable dramatically but to be honest I have yet haven’t cut into and attempted to figure out how to shorten the diameter of the mono auxiliary cords.
I solder the wires on one side, 2 legs of the 4 legs available.
My lack of experience with logic boards is reflected in my pictures but take in mind that I also have one hand.

Link to switch details

My question may be ignorant but When I check the diode, both single channel and dual channel auxiliary cords connected to the stock BSF-1002S tactile switch, the sound is on only when I activate the switch.
When I connect the male adapter to the Xbox adaptive controller and connect it to my laptop, the switch works but the sound is constant when I check the diode.
Is this normal?
And nobody has yet to explain to me what the set back is if I use a 2 channel aux cord (I cut the 3rd wire and cover it in heat shrink)?


texts:
I'm reading a book on split start motors where single phase ac is phase shifted by two inductors at different resistance and inductance.

My question is how does this offer a 30-45 degree phase shift, which is what my reading material is showing? I was under the apparent misunderstanding that all inductors and capacitors shift voltage and current by 90 degrees.

With a single phase input shouldn't the current through the inductors be in phase with each other?


texts: High speed, TTL compatible, high-side switch IC

texts:
I like full integrated automotive high-side switches, such as the ISP452. I like them because of their simplicity, making extremely easy driving grounded loads at standard voltages (12V or 24V) with limited current requirements (1A). I like them because of their robustness. The only big drawback that I see with these ICs is their limited switching frequency.

While most applications would work well at low PWMs, in the hundreds or few thousands of Hertz, some applications require to use frequencies outside the audible noise bandwidth (greater than 20 KHz). When linearization of the output signal is needed, typically with simple LC filters, a high frequency helps reducing the size of the inductor and capacitor.

My question is, why is it so hard to find high speed (>20KHz), TTL compatible (5V PWM drive), high-side switches?

I would not necessarily require an automotive classified chip, but is there any alternative?


texts: "Fully static" HD63B09EP loses state when clock is paused

texts:
The HD6309 is supposed to be a fully static replacement for the MC6809, where "fully static" means that the clock frequency does not have a lower limit. The MC6809 gets the electronics-equivalent of amnesia when the clock is too slow. The HD6309 - supposedly - works fine with slow clocks and - supposedly - the clock can also be paused indefinitely.

I bought a few HD63B09EP on ebay to experiment with. (B = maximum bus frequency of 2MHz (i.e. 8MHz clock frequency), E = External clock generation, P = PDIP package)
I put it on a breadboard, with red LEDs on pins A0 to A7, yellow LEDs on pins A8 to A15 and blue LEDs on pins Q, E, R/!W, BA and BS.
The big button on the left makes an ATtiny85 output the two clock signals E and Q, where Q leads E. The big button on the right connects to !RESET.
1.5k resistors pull the data bus to 0x12, so after a reset, the controller jumps to 0x1212 and increments its address from there. 0x12 is also the NOP instruction, nothing really is happening aside from the address bus counting up.

If the clock is paused only for a short moment, things continue fine afterwards. A few seconds of pause usually cause the address bus to go 0xFFFF for a moment and then continue normally. Longer pauses cause all sorts of weirdness, like the LEDs on the address bus slowly lighting up, flashing LEDs, or the address bus going high impedance and BA coming high, which can only be remedied by a reset. Here's a video of some of the symptoms: https://puu.sh/EVJET/086da059e6.mp4

Inspiration for this was a video by Ben Eater: https://www.youtube.com/watch?v=LnzuMJLZRdU
He uses a 6502-type controller which is also "fully static" and it seems to have no problem with the clock not running. (Can be seen especially well from 22:42 onwards in that video.)
As far as I understand, this should not happen. Did I just stumble upon cheap "knock off" chips? Or is this behavior to be expected? The datasheet does indeed specify 2MHz minimum clock frequency (which equates to 500kHz bus frequency) but how can it then be advertised as "fully static"?


texts: Approximation of second order system, by step response

texts:
I am trying to aproximate a transfer function of a system. The system is a linear actuator, connected to a feedback potentiometer. The following figure is a step respons, with 24 V as input, and the potentiometer position as output.

By this, i have found the time constant, tau, to be 0.132, and the gain to be 0.2069, resulting in a transfer function:

$$ H(s) = \frac{0.2069}{0.132s+1}  $$

This is a first order transfer function, and i've read that a linear actuator system, is at least a second order system.

If i make a step of the transfer function, i will get this:

If i then integrate this, i will get a graph like the first one, and it will be a second order system:

$$ H(s) = \frac{0.2069}{0.132s+1} \cdot \frac{1}{s}   $$

How should i approach this?

The goal is to create a control loop, something like this:

In this system, the output, Y(s), is a position (correct me if i am wrong).

Can the second order transfer function be made this way, and will it be a viable approximation, for a control system?

The standard formula for a second order system is:

$$ H(s) = \frac{\omega_n^2}{s^2 + 2 \zeta\omega_n s + \omega_n^2}   $$

My system does not look like this at all, is there a way to experimentally find an approxiamtion of this?


texts:
Fundamental mixers (in the context of RF Electronics). What are they? What do they do?

http://www.hittite.com/products/view.html/view/HMC557LC4


texts: Why does oscilloscope still shows the signal even though its GND is not connected?

texts: if i connect oscilloscop's + probe to the components's plus side it still shows the signal. But how can this happen without connecting the GND ?


texts:
I am doing a project using a peltier TEC1-12706, however I am stuck on powering up the device. I am using a computer adapter power supply(20V;90W) and I it coupled with a synchronous buck-boost module to bring it down to 12V. During the initial seconds the power supply did handle powering up the module but later smoke came out with my buck-boost converter.

What are your recommendations for the powersupply? BTW, the peltier supply was also coupled with computer cooler which consumes around 500mA and a raspi fan on the other side.
Follow-up question, is the peltier usually reads as short using DMM
buzz test? Ohmmeter around 1ohm only. Sorry, this is my first time working with the component.


texts:
I can't figure out how to do this exercise: (sorry for my bad english)

Design a synchronous sequential network according to the Mealy model with an input and an output which must assume the value 1 when the sequence 000 or sequence 001 or sequence 111 is recognized as an input. The output continues to assume the value 1 whatever are the next sequences.

How can I solve the problem?

I tried with this:


texts: Charging an ideal capacitor through an ideal diode, forever

texts:
Some context for why I am asking the question:

I have application in which I am to charge a supercapacitor from a voltage source which is equal to the the cap's rated voltage. As such I considered using a diode in series with the voltage source in order to realise a reduction in capacitor voltage. This had me thinking about how such a real circuit would work, and how its ideal counterpart would work.

The ideal problem

In the following schematic please assume all circuit components to exhibit ideal behaviour:

Assuming the voltage source starts at 0V, and is then set to 3.3V, the capacitor will begin charging. The capacitor voltage will be equal to the source voltage less the diode forward voltage drop, Vfwd. Vfwd decreases with current, a behaviour that is described by the Shockley diode equation:

where

I is the diode current,
I_S is the reverse bias saturation current (or scale current)
VD is the voltage across the diode
VT is the thermal voltage kT/q (Boltzmann constant times temperature divided by electron charge)
n is the ideality factor, also known as the quality factor or sometimes emission coefficient.

This equation suggests that given any voltage across the diode, some current should flow. If left forever, the voltage on the ideal capacitor should therefore approach equilibrium with the voltage source.

So before I move on to the real problem - in the ideal circuit above, what would the voltage on the capacitor, Vc, tend to if left forever?


texts: Schematic conventions for different supply rails

texts:
I have two ICs in my circuit. They have different supply voltages, 3.3 and 2.7 volts. The voltages are subject to change as we refine the design. I'm trying to come up with labels for these rails. One common convention I see is to use the voltage, so one becomes 3V3 and the other 2V7, but the voltage per se is irrelevant and may change as the design develops.

Is there a convention that would capture the rail's purpose instead of the voltage? It's common to see VBAT, VREG, VIN, etc., but VU1 looks weird.


texts: I have attempted to design my own custom Atmega32u4 board, but when I assembled it it didn't show up in windows device manager. I fixed the problem where I forgot to connect VBUS to VCC with a jumper but it still doesn't show up in device manager. I have also measured all the power rails and made sure that everything got 5v. Any help would be much appreciated.


texts: Inconsistency in the calculation of the gain of an emitter follower

texts:
I want to calculate the gain of the following circuit, but two different ways give different results.

simulate this circuit – Schematic created using CircuitLab

First method:

(This method is explained in the answer by @AlfredCentauri to this similar question, if you want)

I assume a gain of near 1 for the emitter follower and just obtain the input impedance using the Miller theorem (boot strap), and obtain the output voltage from the voltage divider formed from the source resistance 120k and the input resistance of the circuit (which is near 50k), now the gain will be obtained about 0.3, which I believe is the correct answer.

Second method:

But when I just replace the small signal model of the transistor, I obtain something very near to zero (near 0.004) for the gain. I don't know whats wrong with my model:

In the ac model of the circuit with all of the DC sources grounded and capacitors short-circuited, the two \$1k\$ resistors are parallel and are shown as one 500 Ohm resistor in the circuit below. \$v_{\pi}\$ is the voltage across the \$r_{\pi}\$, as in the pie model of BJT. \$I_c\$ is obtained as \$1mA\$. Also \$V_T\$ is \$25mV\$ and thus \$r_{\pi}=2.5k\$ and \$g_m=1/25\$.

simulate this circuit

I simply omit the \$520k\$ resistor in parallel with \$r_{\pi}\$ and the one with the \$500\$ Ohm, and then I will have this equation: (KCL in the output node) (\$g_m=1/25\$)

\$ \frac{V_o}{0.5k}+\frac{V_o-V_i}{120k+2.5k \approx 120k}=g_m(v_i-v_o)\frac{2.5k}{2.5k+120k\approx 120k}\$

This would give approximately \$V_i=240V_o\$ or gain= 0.004.


texts: Electrical neutrality between electrodes of galvanic cell: why is it necessary for current flow?

texts:
I know that as electrons move from anode to cathode through wire in a galvanic cell, there remains in the anode +ions (Zn for example) while - ions are created in the cathode. Afterwards a salt bridge is required to maintain electrical neutrality by moving opposite ions to both electrodes.

My question is why electrical neutrality is necessary to maintain the current flow? Is it because, the abilities of the elements in the electrodes to attract electrons relative to each other change as the starting charges of the elements(as they gain/lose electrons) in the electrodes change ? Does this affect the voltage ?

Secondly, what is meant exactly by maintaining electrical neutrality? Does maintaining electrical neutrality mean that both electrodes have to be perfectly neutral with no charges ?


texts: MCP6548 comparator circuit isn't working

texts:
Hey guys back at it again, sorry.

I am using a standard MCP6548 Comparator to finish the first stage of my project.

simulate this circuit – Schematic created using CircuitLab

OP's schematic.

simulate this circuit

A little tidy-up to separate the rectifier and comparator functions, run R4 downwards to GND and clean up the power supply. Section labels don't hurt either. [Transistor]

The probem is the comparator isn't working when - > +, it aint staying to GND. When the input signal CH1 is Higher than CH2 it should stay to GND. Yes the output of the OPA350 is solid and working as it should.


texts:
I am experimenting with energy harvesting using electromagnetic induction.

I am using the [LTC3108(Ultralow Voltage Step-Up
Converter and Power Manager) circuit.

==>http://cds.linear.com/docs/en/datasheet/3108fc.pdf

I have a few questions.

My input signal is AC 0.8V. Does this circuit allow AC input?
Is a rectifier included in this circuit? Because I have to convert AC to DC.
The red part uses a transformer to convert dc to ac.

In my case, omit this part and enter ac directly.

If you enter ac in the circuit, will the circuit work?


texts: What is purpose of sideway transformer in PSU?

texts:
In another question someone ask about repair of laptop PSU. I cannot find it ATM - possibly because it was closed as about repair and off topic.
However an attached schematic to one of the answers had a sideway transformer (XFRM1 on schematic below)) surrounded by 2 caps (C1 and C2) before transformer to (I presume) lower the voltage. As far as I can tell it doesn't 'do anything' which leads me to think it may be a safety feature. What may be a purpose of it?

simulate this circuit – Schematic created using CircuitLab


texts: Is the current gain value constant for a single BJT ?

texts:
hfe of a npn bjt transistor is given by collector current / base current so to calculate hfe you need to know the collector current and base current (which can be set using resistors) . I have to ask , what is the point of doing this ? You can simply calculate the emitter current using Kirchhoff current rule . This is obviously pointless since the transistor acts like a resistor between collector and emitter and unless you know the resistance of the resistor you can't find the current .

I see in transistor datasheets a maximum and minimum value of hfe . This leads me to believe that hfe is a constant and I do not undersand the point of a varying constant ; I think for a single transistor only a single value of hfe exists which must be measured using a multimeter and the collector current is dependent of the base current so the collector current can be measured .

And also , if the collector current is entirely dependent on the base current (Ic = Ib*hfe) then what is the point of the adding a resistor to the collector end of the transistor ? Surely there must be some change in current if a greater resistance is added to the collector end . I checked this with a multimeter with base resistance of 10k ohms and collector resistance of 330 ohms and I found no change in current when I connect the multimeter in common emitter topology (I think , I connect the emitter to ground and tested the current flowing through the collector )

I think there is a big hole in my understand or a big misunderstanding in my not understanding . Please help

Thank you


texts:
I've constructed a RF transmitter circuit and have been getting numerous problems. after modelling the circuit on a breadboard and testing it we got unexpected readings. these include

411.5hz output from the timer instead of 350hz but correct waveform (square wave)
17Mhz at the base of BJT Q2 instead of 27Mhz and closer to a saw tooth wave rather than the expected square wave

the circuit diagram included shows the layout and pin connection but we used a 7555 timer instead of a 555 and a 27Mhz crystal was used instead of the 25Mhz


texts: Stability of delta sigma modulator with high frequency signal input

texts:
What happens to the high frequency part of a signal (in the region where the quantization noise is high) requantized with a delta sigma modulator, let's say with $$STF = 1$$ and $$NTF = (1-z^{-1})^N$$? I assume it is just lost into the shaped quantization noise, but does it affect also the stability of the modulator?
In particular I know that MASH structures rely on the fact that the signal is still present inside the secondary modulator superposed to the added quantization noise. Does this "high frequency signal" (the quantization noise of the previous stage of the MASH) affect the stability of the modulator? The literature always assume the first order delta sigma is unconditionally stable, but also in presence of an input high frequency signal? My doubts arise from the fact that the high frequency part of the spectrum is used to stuff shaped noise, if this portion of the spectrum is already occupied by the signal itself does that mean that there is less "space" available and this could lead to stability problems?


texts: WiFi modules only doing PHY and Data Link Layer

texts:
Problem Statement: Need a WiFi module that implements just "Data Link Layer Protocol" after taking in data serially.

I am trying to implement all the stacks(Application Layer, Transport Layer and Network Layer) except for the Data Link Layer. All I want is to test my implementation by sending some data over the internet. Therefore I require a WiFi module which can serially take in data and add data-link-protocol- header to it and just transmit it over the WiFi channel.

All I found online was complete stack implementations. Also, if there is a way to do what I want with a device like ESP8266, kindly help.


texts:
I found a Kicad model for SIM MFF2 on the web that I wanted to use in my project but I don't know what is EPAD pin and how to connect.

EPAD is this central biggest pad on the right image. Does anyone know?


texts: Voltage Divider, increasing resistor value for solar tracker

texts:
I am working on a solar tracking device based on arduino and I am using LDR's (Light Dependent Resistors) as voltage dividers.

The wiring is similar to this:

The problem I am facing is that the sensors when in limited light work fine, but when exposed to sun, gives similar readings (not very different results) on all LDR's which I assume is because of very bright light source (sun) and light being reflected from other sources. The LDRs have also been divided using a cardboard structure like this:

I am thinking of increasing the value of the carbon film resistors to achieve greater variations in voltage. Currently these are 10K. Will that solve the issue? Or I should try something else?


texts: How to contract contact resistance via circuit manipulation?

texts:
I have a circuit that turn on a LED when the switch is open and and turns off when the switch is closed, now the switch i have is of not so good quality and upon measuring the resistance between the terminals when closed has a 11.3k ohms resistance, this is now becomes a problem because the transistor will treat it as open even through it is closed.

here is the schematics

I do not want to change the switch (for reasons). How would i manipulate the circuit to accommodate for this contact resistance?


texts: Is there a C671x DSP development kit with more than 16M Flash?

texts: TI's standard kit C6713DSK has only 256K bytes of Flash, which is too small for my application. Is there a third-party DSP kit that has a larger Flash like 16M bytes?


texts: Why does this LED shine brighter with increasing resistance

texts:
A friend sent me two short clips with the first showing a regular light bulb that shines brighter when resistance decreases.

Then a LED which seems to act in the opposite way. Shining brighter with higher resistance.

It's powered by a 9V battery.

We couldn't figure out why the LED behaves this way.

Higher current should increase brightness, as far as I know.
What are we missing?

Anyone that can enlighten us?


texts: Simple switch with optoisolator - CTR related

texts:
I would like to use a optoisolator to act as a simple low current switch, however I'm slightly confused about how to apply the CTR.

From this answer, I should be using the minimum value on the CTR chart of the 4N28 optoisolator. So, for my application, I have 18mA going through the input, therefore the minimum CTR of 10% would yield a minimum output of 1.8mA. Does this mean that I can only have 1.8mA flowing through the output transistor? (the worst case scenario)

The device that I want to switch on requires a 0.52mA to flow through in order to turn on.


texts: Why is Direct Form 2 (Digital Filters) equivalent to Direct Form 1

texts:
According to Wikipedia : The alternate Direct Form II only needs N delay units, where N is the order of the filter – potentially half as much as Direct Form I. This structure is obtained by reversing the order of the numerator and denominator sections of Direct Form I, since they are in fact two linear systems, and the commutativity property applies.

Direct Form I:

Direct Form II:

I don't understand this sentence, what is meant by reversing order ?


texts:
Using the Cadence GPDK045, I generated the following plots of threshold voltage (left) and drain current (right) vs. body voltage for an NMOS device with 45nm channel length. As you can see, over a significant voltage range the threshold voltage actually decreases as \$V_{SB}\$ increases, resulting in increasing current over that range. This is contrary to what I thought to expect, which is that generally the threshold should increase with increasing \$V_{SB}\$.
Is it likely I made some kind of error in the simulation setup, or is this common for very short channel devices, or perhaps MOS devices in general?
In the simulation I fixed the gate-source and drain-source voltages to be equal at 1 V, so saturation is guaranteed.


texts: The mosfet M1 is clearly in saturation as gate and drain terminals are shorted. Why we take M2 also in saturation? I know Vgs1 = Vgs2 and they are identical MOS but i cant justify why M2 should be in saturation, as drain voltage of M2 can be any value..


texts: What is diffrence between Energy measurement ADC and Bridge Sensor ADC?

texts: What is diffrence between Energy measurement ADC and Bridge Sensor ADC. I came across many ADC. One such example is microchip MCP3901. This is an energy measurement ADC. Can i use it for Bridge Sensor application? And Analog device has many bridge sensor ADC like AD7796 ,AD7901 etc. Could anyone tell what is the difference in these two ADC.


texts:
I would like to know if Atmel microcontrollers come with a bootloader. For example I asked a question earlier where other users were saying that a microcontroller could be used instead of a 555 timer which is old.

I realise you can create a delay by programming the chip using AVRstudio?

Basically do they have a bootloader or libraries installed that run this code or do you need to install it yourself?


texts: Beating (possibly) caused by different sampling frequencies?

texts:
So I plugged a signal generator at 0.06 V peak to peak and frequency 1 Hz into my apparatus.
The signal is processed in two steps:
1) signal fed to a first computer, which outputs stuff at sampling freqency 10 Hz,
2) the output from the first computer is fed to a second machine (sampling frequency 16 Hz), and then plotted.

This is what I see:

The peak to peak voltage is twice the one I selected but that might be caused by a load resistance different from the one that the signal generator is expecting (but if you can explain this quantitatively I would be extremely grateful).

Why is there beating? Could it be due to the difference in sampling frequencies?

Thanks.


texts: What is the difference between a grounded tip soldering gun and a grounded soldering gun?

texts: What if any is the difference between a grounded tip soldering gun and a grounded soldering gun?  My son needs one for school.


texts: Type A USB 3.0 with Type C USB 3.0 orientation:

texts: What if I use a USB A - to - USB C adapter cable, with the A side plugged into a USB 3.0 Type A receptacle, and the C side able to accept a slave device, say perhaps a USB C flash drive.  Will the C  side of the cable still be rotationally symmetrical, as would be the case for using type C USB 3.0 throughout?  My guess is no, because there are no CC pins on the Type A 3.0 connector, and only one set of Tx and Rx pins.


texts:
I am trying deserialize data that come out of a LM98640 into 14 bits words:

Attached you can find a figure of the signals out of the LM98640.
http://www.ti.com/lit/ds/symlink/lm98640qml-sp.pdf
(Figure 24 page 31)

I need to deserialize the signals TXOUT1 and TXOUT2:

A differential clock (TXCLK) is also output with transitions aligned with the center of the data eye. Data rates
range from 80Mbps up to 640 Mbps.

(TXOUT1 and TXOUT2 changes as fast as a 640 MHz clock)

What kind of FPGA should i use to work at these rates?

Can i use flip flops to capture the data and a 14 bit wide shift register to pack this into words of 14 bits wide?

Or is it more complex at these rates? Am i going to face metastability problems since i assume a will be facing crossing time domains between the clock sampling the DATA out of the LM98640 and the clock of the FPGA.

The data deserialized is going to be provided to a NI DAQ or stored in a RAM.

What kind of xilinx FPGA should i use?

Thank you for your help


texts: 74HC595 Shift register - output pin polarity

texts:
Most shift register tutorials I've seen have the output pins connected to ground (for instance: http://www.arduino.cc/en/Tutorial/ShiftOut), however I've seen at least one circuit that connects them to VCC instead (https://learn.adafruit.com/assets/7766).

These circuits both use the same chip (74hc595), and aside from reversing the LEDs look otherwise identical.  is there something I'm missing?


texts: Why is not possible to light a bulb without closing a circuit by using two batteries

texts:
I'm new to learning about electricity. I have learned that Electrons moves from - to + when there is a voltage differential.

My conclusion is, that I can connect the plus side of one battery to a bulb, and connect it to the minus side of the second battery without closing a circuit.

This way, the electrons will move, and the bulb will light?

Is it will light for at least a few nanoseconds?

Bonus: There is an online website that can help me create the diagram and test it? or just share here the image?

Is it the truth that the bulb will be lighted for a few nanoseconds? (see answers below)


texts:
I have a phase regulator and I'm using it for regulating the RPM of a fan - centrifugal blower. The motor is a shaded pole induction motor (220VAC, 28W).

The regulator is working fine, but if the RC Snubber (R8+C8) is disconnected (due to the failure of C8 or R8), the voltage and current are getting out of phase and false triggering / turn off of the triac occurs, which leads very quickly to overheating and failure of the coil of the induction motor.

What type of capacitor should I use to minimize the chance of its failure (I’m using this regulator for 8 hours a day)?
Or is there a way to add additional circuit for protection, if such failure occurs?

I’m currently using Polypropylene capacitor rated for 250VAC/400VDC (Wima MKP 10 - https://www.wima.de/wp-content/uploads/media/e_WIMA_MKP_10.pdf). For the resistor I’m using 1W/Metal Film.


texts: Why does this LTC1440 Comparator switch so slowly?

texts:
I am trying to build an undervoltage protector for a 6S LIPO battery. My idea was to use a comparator to switch off an NMOSFET when the battery fell below a preset voltage, 20V:

R20, R21 and C20 create a crude voltage supply for the LTC1440, VCC varies between 6.6V and 8V in the simulation.
R10 and R11 bring the 20V down to 5V.
R1, R2, R3, R4 and R5 are calculated according to the datasheet.

When I run this through LTSpice, Vin drops linearly from 1.24V to 1.06V (thus crossing the VRef 1.182 at about 20V input):

but VOut falls slowly from about 6.5V to 0V after the 20V threshold is reached:

as a result, the load is switched off slowly:

I expected it to switch off completely at exactly the threshold; why is this not happening?


texts: Not earth grounded old analog oscilloscope

texts:
I have an old analog oscilloscope:
http://www.ebay.co.uk/itm/Advance-OS-240-10MHz-Dual-Trace-Oscilloscope-with-Instruction-Manual-/261220770137
It doesn't have 3 pins power connector instead it has 2 pin connector(Line and Neutral).
It has external earth symbol on it. I think it looks like it is not earth grounded.
Are modern oscilloscopes earth grounded for the GND part of the signal or it is for safety? I mean are they grounded through Line or earth ground?
I mean housing systems are such that at most of them earth and neutral are connected to each other at the end.

My question is : Is my oscilloscope measuring signals correctly?


texts:
I want to increase the Bluetooth Low Energy transmission range of my ESP32 with IPEX connector.
How can I select the right antenna?
Do I have to take a look only at a 2,4 GHz WiFi antenna, the antenna gain and the right impedance or do I have to take something else into account?


texts: What should I be using to amplify a heat flux and load cell signal?

texts: For my senior design project, we have various sensors (Thermocouples, Heat flux sensors, load cell) plugged into our DAQ. We are using LabView and some National Instruments devices (ugh) and discovering that our loaned equipment doesn't have the resolution necessary to read accurate values from our heat flux and load cell sensors. The DAQ can read around a 100 mV range effectively. The heat flux sensor provides values in the microvolt range (0-100uV IIRC) and the load cell is in the milivolt range (0-5mV). We're looking into getting a better DAQ, but I was wondering if there is a way to easily amplify these signals into the volt range? Our grad student we have working for us is very concerned about impedance and other factors that can throw off our readings and is very against any sort of amplification circuits. Is amplification a viable route, and how would we go about amplifying the signal?


texts: I am working on a new product, hoping to start up my company with it. I'm an electronics noob. I want to know whether AVR microcontrollers are open source, and if I use them, should my product be open source as well? Because Arduino also uses an AVR chip and its schematics are open.


texts: What equipment do I need to reprogram an old garage opener remote?

texts: I recently took an interest into hardware programming, and instead of buying something like an arduino I was wondering if I can reprogram the microcontrollers on old garage remotes or tv remotes. I don't want to anything fancy, just want to test some things. If I can do that what equipment would I need?


texts:
I need to design a timing circuit. After a duration of 6 months a  LED must come on. The LED can then be turned off at the press of a button and the 6 month count-down must begin again. Anyone have any idea where I would start? Is a 555 timer capable of doing something for a time of this duration or would I need somthing else? Any help would be greatly appreciated..

[added] it will be used as a reminder to change a water filter so it should be powered off a small battery..something small, easy to setup and with a low current consumption would also be handy..any help appreciated..thanks for the previous input..


texts: Why does compact fluorescent lamp (CFL) save more energy?

texts:
I read information about fluorescent lamp and compact fluorescent lamp (CFL) but I still don't understand why CFL saves energy and produce the same amount of light?

Maybe the electronic ballast consume less reactive power than the traditional ballast?


texts: Driving PWM lights with parallel darlington arrays

texts:
I am building some service light arrays, which I want to operate using the Arduino's PWM outputs.

This lighting is going to be powered by 5V OR 12V with a nominal current of 700mA per array. There will be 4 arrays total.

Elsewhere in my design I am using ULN2803s; I am thinking of again using this chip. There is obviously a problem though; as the datasheet notes, the maximum collector current is 500mA. However, since the ULN2803 happens to have 8 darlington arrays, I was thinking of putting the darlingtons into parallel pairs, giving me 4 pairs with a max current of an amp. I do know that one of the tradeoffs for the darlington's high current gain is a slow turnoff time, but I am reasonably sure that the accuracy of the PWM is not a very important consideration.

There are a few things on which I am hoping this question can answer for me:

Does anyone know the total power dissipation that this IC can handle? I can see that the maximum Vce is 50V and the maximum collector current is 500mA, so is it safe for me to assume that the maximum power dissipation for the entire chip is 200W or thereabouts?
I know there is going to be an issue with mismatched transistors leading to current hogging, as noted in this wiki article. I know it has something to do with the fact that the voltage drop across the darlington pairs will be different between transistors because of minute manufacturing differences, leading to different collector currents in each pair and worst case to a failure in one of the parallel pairs. I also have found that it can be solved by putting a small resistor on the emitter or collector of each darlington in the parallel pair. I'm not exactly sure which as it seems there is some conflicting information. Additionally, I'm not sure how to calculate this resistance given the datasheet and my parameters. Could anyone shed some light on the exact theory behind this, and how I would go about calculating this resistance?

Alternatively, is there another chip or collection of discrete components that you would recommend I use? I would prefer an array, if possible, to minimize assembly costs.


texts: Can I reprogram my Arduino via a wifi shield?

texts:
My Arduino is hooked up to some lights over my aquarium and I can control them from a web browser on my LAN. I wonder if I can modify the program on the Arduino without having to plug it into a machine via USB which would be a little inconvenient. There must be some way I can take advantage of the wifi connection.

I have used Pololu's wixel shield to send programs wirelessly (it just acts as a serial port radio) but that's a different technology than my WiFi shield.

Does anybody know of a way I can do this via WiFi? Maybe if I upload new code to the flash memory in the WiFi shield, it could then bootload from the flash memory? I'm not sure how to do that or if its even possible.

Perhaps a completely different approach would be simpler?


texts: AC adapter not working on one outlet only

texts:
I have a switching AC adapter with an LED on it that shows when it's plugged in and receiving power. It works fine in all my outlets except one. But this one outlet works because it powers everything else fine. I tried removing the power strip and plugging the adapter in it directly but still the LED is off.
What could explain this?


texts: Voltage Regulator that gives an output of 12V and 10A

texts: I'm looking for a voltage regulator that takes 9V-20V input voltage and gives an output of 12V and 10A. I found a couple of buck-boost regulators that can do that but i just cant seem to simulate it. I need something that i can simulate in multisim or LTSpice so that i am 100% sure that it would work in real life. Can anyone please help me with this?


texts:
New to this site so hoping it's the right place to ask.

I'm trying to prototype something for use in a retail store and an idea a teammate had was using an RGB sensor to detect both ambient color as well as a proximity sensor to detect when someone is near the display and get the color of their clothing. We'd then use a series of LEDs to recolor the display to match that customer.

The problem I'm running into is that most RGB sensors I've found seem to only be accurate at a few inches (at most) and for proximity sensors it's a bit better but not enough for use in a store setup.

I have a pretty limited electronics background though so I'm mostly browsing Arduino suppliers. Does anyone know if you can get sensors with a larger distance and if so can they be controlled by something like an arduino?

One potential fallback is a camera like the MS Kinect with a full on computer but the client is weary of having a real camera for legal reasons.


texts: Do I need an external oscillator for PIC16F887A?

texts:
I'm working with a PIC16F877A. Do I need to add another external oscillator to pins 13 & 14 or can I use its internal oscillator with 4MHz frequency?

I don't need precise timing in my project. I just want a delay of 10 seconds which I can generate with an internal 4MHz oscillator.


texts: What's the highest precision achieved for an ADC?

texts:
I was browsing Digikey the other day (don't you?) and I stumbled across some 32bit ADCs, there were offerings from Linear, TI and Analog. One stood out, the AD7177 from Analog which states in Table 7 on page 19 of the datasheet that at 5 samples per second it's got a staggering 27.5 effective number of bits (and an RMS noise of 50 nanovolts). On the other hand of course, it's accuracy is significantly worse, but still.

This got me wondering, if a relatively cheap off-the-shelf ADC can hit an ENOB of 27.5 bits...

What's the highest ENOB ever achieved? Be it in some super integrated IC, some piece of stupidly expensive lab gear, a lock-in amplifier? Has anyone ever beaten 27.5 bits of precision?

[edit] A bit of clarification I'm not looking to buy/build or otherwise aquire such a device I'm just curious what the current state of the art is, modern atomic clocks have hit 3x10-18 (3 quintillionths) uncertainty, where do modern scientific voltmeters sit on the scale?


texts:
I am curious on how capacitive sensing work. How does it sense hand gesture, or measure water level when the distance between the capacitance plates are large (5-10cm)?

I thought that capacitance plates need to be very close to each other to have inducing of electromagnetic waves? For example, a normal capacitor consists of a nonconductive layer sandwiched by two conductive layers, so the distance is very small (< 1mm).


texts: Strange behavior with CA3130EZ op amp in follower configuration

texts:
I am assembling a simple follower circuit and am confused about its behavior.  In the diagram below, R1 = R2 = 15 k\$\Omega\$.  As expected, the voltage at the non-inverting input of the op amp is 2.5V.  I expect the output at Vout to also be 2.5V.  When I use a 741 for the op amp, everything works as expected and Vout is 2.5V.

However, when I use the 3130EZ op amp, I find a significant voltage drop between the inverting and non-inverting inputs (which seems to violate one of the fundamental op amp principles) and Vout is not 2.5V.  I've tried varying the voltage supply to the op amp from about 5V to 15V and this causes Vout to change.  I've also tried replacing the op amp and the results are the same.  Any ideas why the 3130EZ would behave so differently from the 741?  I'm pretty new to op amps and electronics in general, so it's possible I've missed something really obvious.


texts: Providing voltage to USB port and battery terminals from same voltage regulator. Safe to do?

texts:
I’m trying to use my old smartphone as an IP camera. I hooked up a voltage regulator providing 4.4V straight to the battery terminals and it works perfectly. However to have the phone boot automatically after a power outage I need to provide voltage to the phone's USB port as well. I
I have this setup running right now but I'm not sure if it will damage anything in the long term.
My questions is:
Is it safe to hook the USB cable straight from the voltage regulator? Isn't the voltage regulator essentially ‘charging’ the ‘battery’ which in this case, is the voltage regulator itself?


texts: MCP2221A USB to USART with Windows 10 Drivers

texts:
I just designed a board using the MCP2221A USB-to-USART Bridge device from Microchip. My development platform is currently on Windows 10. I have downloaded all of the files and utility programs I could find from the Microchip website. I also downloaded the file set MCP2221 Windows Driver 2014-10-09 and installed it. The driver install package ran without problems, so the driver install appeared to work.

Next I used the MCP2221 Utility program to attempt read the chip device and possibly program it. This is where Windows 10 appears to fight the device and driver. When plugging my PCB board into my PC Win10 gives me the following popup error:

Apparently Win10 will not allow the driver to proceed because the blank MCP2221 device does not have any VID or PID information in it. That is the reason I was using the MCP2221 Utility--to initialize the PID and VID and maybe other items. Below shows the Device Manager listing...

...showing that the device descriptor failed. The whole point in using the MCP2221 Utility is to setup this information.

Microchip's Web Forums were no help at all. All comments pertained to WinXP and Win7. No drivers, app notes, or other support items have been upgraded since 2014.

Has anyone encountered this problem with Win10 and devised a work around?


texts: Getting 10 LEDs in dual parallels to be brighter

texts: I've go a small scale strobe light and from the output I'm using a power transistor to amplify it and Then I have two sets in series of 5 LEDs in parallel with one 200 ohm resistor after the transistor (9v Vcc). The problem is that is I use it with one LED its very bright, but when I use the Dual 5LED parallels the LEDs are very dim and I need them to be as bright as possible. Probably very simple, but I could use some help with how to go about it.


texts: Bidirectional shifting in VHDL efficient implementation

texts:
I need to implement a variant of the bidirectional shifting (I basically need to process the part of the less significant bits that are being lost during the right shifting specifically). Since it is a slight variant I need to implement, I basically was wondering how efficiently could it be modelled a bidirectional shifting in vhdl, leaving the specific processing I need to do for the moment.

Assuming the shift parameter n could be both positive or negative I would perform in parallel left shifting and right shifting by n, and then using the sign of n I would select between the left or the right shift (so basically I would use the concurrent stamenent when ... else). I'm not entirely sure of the efficiency of such code because the compiler would instantiate probably both shifters. Is there a best way to achieve such result but more efficiently? (I also would like to avoid if possible working at bit level to implement such shifter, i'm just asking if there's some kind of "recipe" that it's worth to be aware of).

By the way... I'm speaking of "barrel shifter" not "shift register", I'm not interesting in keeping the result at all.


texts:
I am looking for a sensor that could be mounted on the front of a car, to tell the distance to the car ahead, to detect safe driving distance.

I was thinking of the possibility of a laser perhaps, but I am unsure of where to get a sensor like this, or if I am going to have to build my own.

What are some feasible and inexpensive ways/products to sense this distance?

Please note, I do not intend to break the rules by asking for specific products, I am just asking what should I search for.


texts: Biasing circuit schematic clarifications

texts:
I am designing a biasing circuit using application note from AMPLEON.
I have following doubts on which I need clarifications:-

The switch S1 functionality in this circuit. I understood the functionality to some extent.

In "6.6 Full schematic" section, It has been mentioned that:-
When Switch is in "stand by" position the nominal gate voltages are applied and drain voltages are disconnected.
When the switch is in "VD_ON" position the drain voltages are not fully on.
What is the meaning above line? When does VD is generated?

Resistor Value selection

Some formulas have mentioned to calculate resistor values based up on Drain voltage VD. I am not understanding how these values are calculated.
Can someone guide me on this?


texts: Non-isolated DC-DC converter for power supply and equipment at remote location (on top of a tower)

texts:
I am designing a DC-DC converter system for powering equipment in remote locations (on top of a tower.) Each device needs 150 W of power.
I designed DC-DC converter both at ground-level power supply and for the remote equipment. Here is the logical connection:

This is how system will be deployed:

"REMOTE EQUIPMENT" to "POWER SUPPLY" has maximum distance of 100 m (or more if power cable somehow not routed efficiently.)
The DC-DC converter in "POWER SUPPLY" and "REMOTE EQUIPMENT" share the same ground.
Question:

Is a non-isolated (shared ground) topology like this is problematic for this use case? Should I use an isolated topology instead (flyback with transformer?)
How would a lightning strike (on top of the tower) affect remote equipment and ground-level power supply if this topology is used?
If a grounding cable at tower that connecting busbar to ground somehow disconnected, what risk exposed to remote equipment and ground-level power supply?
If a grounding cable connecting busbar to busbar somehow disconnected, what risk exposed to remote equipment and ground-level power supply?


texts: Can change number of data bits in NI LabVIEW's VISA serial?

texts: I need to send 16 bits of data through serial UART to LabVIEW. I have 16bits of data frames with 1 start bit, 1 stop bit, and 1 parity bit. Is it possible to change the number of data bits in VISA component of NI LabVIEW to 16bits.By default it is 8 bit. is this impossible change number of data bits to 16 in VISA serial?


texts: How do you choose loops for the loop circuit method?

texts:
I need to understand how to choose loops for the loop current method of circuit analysis; ideally I'd like to be able to do it by means of an algorithm, so a vague intuition isn't sufficient. Can someone please clarify exactly how this works for me, in terms of necessary and sufficient rules and/or an algorithmic solution?
The only explanation I seem able to find is the pair of rules (1) "make sure every element is included in a loop or mesh" and (2) "make sure at least one element in each loop is not part of any other loop or mesh". These do not suffice to correctly choose loops, as is evident in the following trivial planar example, where the choice on the left clearly satisfies them:

Moreover, there are situations where a clearly sane loop selection fails to satisfy (2), for instance almost any choice including the central mesh as a loop in this example (including the standard choice of using the 5 meshes):

In this example I've included a weird alternative "solution" which satisfies both rules, but it won't be valid, since it involves only two loops which share no elements. Presumably (2) is just a heuristic for ensuring independent equations and not actually necessary, but that doesn't help me know what IS necessary.
O glorious lords of the electronics stack exchange, please save this lowly and ignorant brother!


texts:
I have problem with understanding the feedback part in flip flop. Consider a flip-flop circuit containing just two NAND gates as shown in the picture below:

Problem 1) Let A & S' be the inputs of 1st NAND gate and B & R' be the inputs of the 2nd NAND gate. What will be the values of A & B when both S' & R' are 0? (To find output we need to know the inputs, but here the inputs are depended upon the outputs of each other which makes me confused!)

Problem 2) If A & S' are 0, Q will become 1. Since Q=B, B will also become 1. Now let R'=0, then  Q' will become 1. Since Q'=A, A will change to 1 from 0. Is this analysis true?


texts: Building homemade low inductance capacitor

texts: i am trying to build a low inductance capacitor. I could just buy a doorknob capacitor but i don't wanna pay that much. So i know that you need a dielectric, i am using overhead transparency sheets. And im just using aluminum tape as my conductor. Now i know how to build these, i just dont know how to build it to get close to my capacitance i need. I want 4700 pf, i know i have to stack so the whole thing isnt so big. How do i figure out how big to make each sheet and how many sheets i need to get to my capacitance i am looking for. Any help is greatly appreciated!


texts:
I was fiddling around in LTSpice for a project I'm working on.

This circuit is a basic preamplifier and a low-pass filter. But this question refers solely to the amplifier stage. The opamp is the "universal opamp2" model.

However, the resulting waveform has a 4.5V DC bias. Since I intend to run this from a single-supply source I was planning on biasing the input signal at 4.5V so the opamp can swing the signal to 0 and 9V. But I hadn't added the bias yet.

Without C3 there is no bias and the output waveform is as expected. If I add a, say, 1M resistor from the noninverting input to ground, creating a high-pass filter, the bias is gone.

The C3 is supposed to remove any DC component from the input signal.

I figured this was just SPICE being stupid, but is this something that would be expected in practice?

Nodes:

V[n004]: Input signal (green)
V[n005]: Signal at non-inverting input (cyan)
V[n006]: Signal at opamp output (red)


texts:
A customer has asked:

  I want to slow down a small hobby
  sized DC motor to a user variable
  range that runs from slow to zero
  RPM. I would simply use a wall wart
  for a power supply and a potentiometer
  to set the speed but the load on the
  motor might change slightly. Although
  the drag on the motor will be very
  low, if that drag does change, I would
  like the speed of the motor to stay
  fairly steady in spite of this.

  A couple of people told me to use a
  PWM controller for this purpose
  because a PWM has a range of 0 to
  100%. Of course this in not in RPM.
  One other person said that the motor
  might not slow down properly because
  the hertz rating on the PWM could be
  to high to allow this or because the
  pulses might not have an adequate
  amount of strength to excite motor
  enough to move it at all when the
  motor speed is set near zero.

  I thought about using a steper motor so
  I looked a an Adafruit
  Motor/Stepper/Servo Shield for Arduino
  kit - v1.0 but I know almost nothing
  about this stuff so I don't know if
  this would be just the right thing
  either.

  I want to turn a knob to vary the
  speed of a motor form a few parts of
  an RPM up to a "slow" speed ...say 60
  RPM? ...maybe?

  Oh ...comparatively inexpensive and
  simple to set up would be great as
  well !

Any thoughts?


texts: Need help with finding the electronic schematics

texts:
I'm trying to find what kind of circuitry(circuit components or schematics) is used in this anemometer: http://www.nrgsystems.com/sitecore/content/Products/5966.aspx
There are a lot of details about mechanical parts but not the electronics in their website. It just says it is generating ac sine waves that's all. I want to know whats in the anemometer.


texts: Switching power supply only works when warm

texts:
Update

With the multimeter and a steady hand, I've found the 3843B PWM controller Vcc pin is 12V when the supply is on, and 8.2V when it is plugged in but cold. Datasheet says it needs 8.4V Vcc to start-up so heating it is lowering its startup voltage or increasing the Vcc just enough.

To test the theory I supplied external 9V power to the pin, to "jump-start" the power supply. It worked!

So now, I think I need to find where this 8.2V is coming from so I can work out how to bump it just that little bit more, maybe by replacing a diode or something.

How this "start-up current" is usually generated on power supplies? Maybe from the pictures you can point to some probable locations I should look? What could be the cause of the low start-up voltage? Thanks in advance.

Okay, this is a weird one. First time on this Stack Exchange, work with computer science, and have only basic electrical knowledge, so beware of any possible misunderstandings below.

Some context

I have an "universal" laptop power supply, one you choose the desired output voltage with a switch, it goes from 12 to 24V. Since some time ago it started working only when warmed up. So to start using it, I had to warm it up with a hair-dryer and then couldn't leave it turned off for too long, or it would cool down.

I decided to fix this for good because it was getting worse over time (needed more temperature to start-up), it looks fun, and I am broke. So I opened it up, armed with a multimeter and started probing. It takes the 110/220V input AC, rectifies it and then passes it through a MOSFET (gate, I suppose, connected to some signal generator, the frequency of which maybe determined by the voltage selector) and onto the main coil, which gives our output voltage which is rectified again, filtered and then out. So the problem is, whatever drives this MOSFET wasn't working when cold. I narrowed the problem to 3 ICs and did the logical: warmed them one-by-one with a lighter to find which one was problematic.

TL;DR: The actual question

So I narrowed the problem down to an IC called "3843B" which turns out to be a "high performance current-mode PWM controller". So, heating this IC (or something on its close vincinity) gets the power supply going. After it starts working, then everything is OK. Below is a photo of it.

What could be causing this? Which of the suspect components in the photo could have a failure mode which makes it work only after it's hot? What can I do or which components do I replace?

Close-up of suspect

Board overview


texts:
I bought 6 month ago a controller for a screen (T.VST59.031) https://fr.aliexpress.com/store/product/Free-Shipping-T-VST59-031-V59-universal-definition-LCD-TV-panels-HDMI-LCD-driver-board/1270386_32510541373.html

Everything worked fine until now, one 5-pin integrated circuit broke.
I managed to get it out of the board and it was written on it "GG6M". But I can't manage to find anything about it on the internet.
I know it has something to do with the transmission of the power signal because the red led indicating that the screen is powered but off is working, but if I try to turn on the screen using the IR controller or the power key, the led stays red and the screen doesn't start.

Here are some screens : https://imgur.com/a/PxhVT

The whole board
A close view of where the integrated circuit was after I took it off
A close view of the integrated circuit before I took it off
Another view of the area where the circuit was

Do you have any idea of what it could be or how I could find it out ?


texts: Different voltage between the solar charge controller and the battery

texts:
I have a solar "box" project with a 10 W, 12 V panel and I noticed something when I was testing the battery voltage (two 12 V battery in parallel). When I measure the battery voltage directly from both batteries, it shows 13.86 V, but on the charge controller battery input it shows 14.56 V. This only happens when the controller is fast charging, but when it isn't charging the battery (pulled out the panel cable) it's almost the same (0.1 V difference). When the controller is not connected to the battery at all, the voltage on the cable I used to connect it is the same voltage as the battery.

What I'm asking is, is this normal or is my controller acting up?


texts: Use closed loop torque control based on motor position to simulate a dynamic load

texts:
The goal is to use servo + gearbox to simulate a screwing process millions of times.
A screwing process is characterized by a low torque at first (the screw enters the material) and once the screw head touches the surface a steep torque curve starts. See the attached image (a).
Example of a torque ramp: 5% to 90% of max motor torque within 2 rotations or 720deg
I believe I can realize this screwing-simulator with a closed-loop torque control on a variable frequency drive (VFD) like Siemens S120 and using a synchronous motor servo like type 1FT7 and a torque sensor. The torque setpoint of the VFD needs to be updated based on the measured angle (external encoder).
The simulator is basically a motor in regenerative mode, thus requiring a brake resistor.
Is this concept of a screwing simulator reasonable?
How accurately can I control the torque?
If the torque setpoint is set to zero, will the servo (that is behind a gearbox) just rotate when I apply torque by hand? (see attached illustration (b) of the thought experiment)


texts: BOOT0 vs BOOT1 circuit design in STM32f103 (ST-LINK)

texts:
I have a question about designing st-link v2. According to the schematics provided by st.com Please help me in analyzing this schematic. Why boot0 was pulldown with a 100k resistor but connected boot1 without GND resistor.

According to the AN2586, the pin boot0 and boot1 must be connected to a VCC or GND 10k resistor.
But this point is not met


texts: Can I use this resistor to safely discharge this capacitor?

texts:
I build a circuit that charges a 400V 4.7µF capacitor to 307V.
I have been discharging this capacitor by shorting the terminals using a large piece of metal. The capacitor makes a small spark and then my multimeter reads 0-5V from the capacitor.

I have heard in various places that this is bad for the capacitor because it causes a large current spike that can permanently reduce the capacitance and might blow up the capacitor. People also recommend using a resistor to discharge the capacitor.

I found a listing for a resistor on Amazon that has a resistance of 1K ohms and can dissipate 100W of heat.

I don't know if it is necessary to use a resistor like this or if a regular 1/4W resistor would suffice.

I calculated that at 1000ohms and 300V there should be a current of 0.3A and a wattage of 90W. This made me think that I need this big resistor.


texts: How to create a footprint with a pad on the component side in gEDA pcb

texts: I've read a bunch of tutorials, but can't figure out how to do this.  What I want is a pin where the pad is on the component side instead of the solder side and the hole is plated so that it can be connected to a trace on the solder side.  Most of the parts on this board will have pads on the solder side as usual.  Is there a way to force this when creating a new footprint (this is what I would prefer since this particular part will generally be handled this way)?  If not, can it be done when laying out the board using a footprint that would normally put the pad on the solder layer?


texts: Why do some Arduino-compatible boards provide a crystal for the CH340?

texts:
I have an uno-shaped Arduino compatible which uses the CH340(G) serial to ttl converter chip and it is connected to an external crystal.

I also have nano shaped compatible which uses the CH340(C) serial to ttl converter chip which has no external crystal although it does have pads ready to accept one.

My question is: Why does the one board's serial chip require a crystal and the other not? is it because they use different CH340 variants? And also why is there the need for the space for an external crystal on the smaller board?


texts: LM317 or DC to DC Buck converter for solar charger

texts:
for my studies I have to complete and analyse an electrical project; I am doing a solar panel charger, the solar panel will be connected to a USB power pack to store the electricity generated for phones etc to be charged.

I am aware I need a regulator, but my research has me stuck for which one is the most appropriate. The solar panel will be 80w 12V being converted down to 5v.
Do I want to use a linear LM317 or is a DC buck converter a better choice? It is going to be on the inside of a tent, so heat from the circuit must be minimal and need the most efficiency as solar panels do not produce good efficiency as it is.

Im a complete newbie to all of this, and I am completely stuck! So I would appreciate any help!! Thanks in advance :)

EDIT:
The USB power pack which I wish to use is 13,000 mAH with the specs:

2x 10W (5V, 2A) USB outputs
1x 10W (5V, 2A) Micro-USB input (flat white Micro-USB cable supplied)
auto-on
four-LED status system
no passthrough charging

I am going to buy a pre built voltage regulator as I am running very short of time, just need to know which type of one and what size I need.


texts: I have been looking at a lot at Battery management system/protection circuits lately and there are components that I can't identify. Can anyone tell what is the name and function of the component I encircled in the image? I am thinking that that these are fuses but I might be wrong.


texts: Nonlinear time dependent equation in simulink

texts:
My question is about time varying nonlinear equations in simulating of them in simulink. in nonlinear time independent equations x,Dx,D^2(x) are made with multiple integral block like the picture in below:

For nonlinear time varying equations like below, for making D^2(x(t)),D(x(t)) and x(t) what blocks should be used for having varying 't' in equation and how?


texts: How to setup and simulate differential TDR (Time Domain Reflectometry) in Cadence

texts:
I want to do differential TDR simulation in cadence virtuoso. I have a differential channel, made of Tlines and interconnects (passive componenets). How to setup the TDR simulation to get impedance over time? I know, I have to terminate both n and p channel with 50 ohm each at the output. I have to do also in the input. But how to connect the step voltage source at the input and get the recuired impedance over time from the channel reflection? Should I connect 2 step voltage source at the input of n and p channel ( one is +1v and another is +1v)? Then how to calculate the impedance at the input from the reflection? Can anyone help me.

Note: I am using virtusos version IC6.1.7-64b.500.4, there is no rflib. So I cannot use Balun ports.


texts: Choice of mosfet transistor for linear operation (voltage controlled dummy load / current source)

texts:
BACKGROUND
I have built very simple dummy load to test thermal behavior of some switching power supply (5V 5A). Vbat is 8-9V from 6F22 battery. Resistors are oversized to reduce working temperature.

Photo:

It works well for the purpose for which it was built, but I probably should add some capacitor at op-amp noninverting input.
Now I want to build better version of this and use 0R1 shunt with low temperature coefficient, add voltage control and use diffrent transistor. BUZ11A is obsolete and I want to use something with bigger package (like TO-247) and use CPU radiator with fan.
In current version I have choosen BUZ11A from few mosfet types I had in my workshop because this transfer characteristic was clear for me and I can assume that this transistor needs Vgs from ~4V to ~5V to get from 0A to way more than 5A (which is my requirement).

But many high power transistors have "incomplete" transfer characteristic documented like this:

Question 1:
Why this is documented like this? I should not use this transistor in this area (low Vgs)? It is not stable at this region?
Question2:
Can I use big transistor (like BUZ11A) to regulate small currents? Let's say I want to use big mosfet transistor to build voltage controlled current source regulated from 0.5mA to 5A.


texts: Are the Arduino sensors/components compatible with Raspberry Pi 3?

texts:
I am trying to build my own irrigation system. Before I was thinking to do this using an Arduino UNO controller, however, I decided to switch to a Raspberry Pi 3, which suites my needs better.

What I got left are some humidity sensors, such as the one here. Are these going to be compatible with the GPIO of the Raspberry Pi?


texts: Maintain a Switch Position until Power Off?

texts:
I've got an interesting problem in which I have two circuits.
For simplicity, let say that circuit A powers an LED at 3.3v with a switch, and circuit B powers a load at 5v.
Circuit A is in fact a voltage regulated portion of circuit B.

Now lets say I want to be able to complete circuit A and have the LED on but the switch for completing circuit A will only function while circuit B is off. So if I have chosen to turn on the LED, once I complete circuit B (giving power to A) I can no longer turn circuit A off until circuit B is off again.

Essentially, I only want to be able to use/interact the switch on circuit A while circuit B is open. Once circuit B is closed, whatever position the switch for circuit A is in, will remain in that position until circuit B is opened again.

Thanks for any help!


texts:
I am using a Diodes AL8871Q IC to power a XHP70 LED at 3.4 A. My thermal cam shows the MOSFET at 108 degees C after 60 seconds with PWM control running at 40% duty. Is this expected?
MOSFET I am using is a IRLB8743PbF
Using the provided excel calculator sheet, I plugged in my values:

Calculator shows these outputs, so I am wondering if it's ok. My room ambient is about 26 degrees C

I get a recommended schematic 1 - Buck topology

Here's a WIP of how am planning to mount the driver


texts: Why everyone are building tesla coils instead of multipliers?

texts:
When I see someone want to get high voltage - we see tesla coil.

Why everyone do that instead of building Cockcroft–Walton generator? Are there any issues with Cockcroft–Walton generator, making it less fun than tesla coil?


texts: I wonder if there is anything common in the concept of 'State vector' and 'State-Space'? Are they anyway related to each other or they are completely different ideas?


texts:
I've been working on a BLDC control circuit for my senior year project. Recently I confronted a problem and couldn't solve it after days of googling which is quite frustrating for me. Here are some details.

I use IR2130 mosfet driver -controlled by an arduino- for 3 phase H bridge.

High side PWM signals can reach 90% max duty cycle.

I use IRL540 Logic mosfets which have 16v Vgs voltage. (I have 12v rectifier)

This is the curcuit I use. I simplified it by drawing only 1 phase other phases are present in real circuit.

My questions (problems) are:

1- My arduino generated input signals are fine but IR2130 doesn't generate High and Low side mosfet signals.

2- I grounded both arduino and circuit on the same GND still no effect on it. Is it necessary?

3- I suppose Vso pin is necessary to discharge Mosfets. So I grounded it using a small resistence. Am I doing right?

4- Even if I messed up the bootstrapping, shouldn't low side mosfets work just fine?

Any help would be appreciated. Thank you!!!


texts: Capacitive medium range sensor with STM8

texts:
I am trying to replicate the behaviour of this library: https://playground.arduino.cc/Main/CapacitiveSensor/ with an STM8, but I am not able to do it.  I want to detect the proximity of the human hand from about 10 cm. I don't have sensibility, i can only detect a strong pression on the capacitive sensor (aluminium foil) and even the heartbeat, but no the proximity. With this library I had a perfect beahiour. I am using a 1 Mohm resistor.
This is a piece of code:
    disableInterrupts()

GPIOD->ODR &= 0b11111101; // sendPIN D1 to LOW

GPIOE->DDR &= 0b11111011; // receivePIN E2 to INPUT (=0)
GPIOE->DDR |= 0b00000100; // receivePIN E2 to OUTPUT (=1)
GPIOE->ODR &= 0b11111011; // receivePIN E2 to LOW
// delayMicroseconds(10)
enableInterrupts();
for ( t = 0; t < 1000; t++);
disableInterrupts()
GPIOE->DDR &= 0b11111011; // receivePIN E2 to INPUT

GPIOD->ODR |= 0b00000010; // sendPin High

enableInterrupts();
for ( t = 0; t < 1000; t++);
//getADCValue();
In = (GPIOE->IDR & GPIO_Pin_2);

while (In == 0) {
    In = (GPIOE->IDR & GPIO_Pin_2);
    total++;
}

//stopTime = TIM3->CNTRH;

disableInterrupts();
GPIOE->ODR |= 0b00000100; // receivePIN E2 to HIGH
GPIOE->DDR |= 0b00000100; // receivePIN E2 to OUTPUT (=1)
GPIOE->ODR |= 0b00000100; // receivePIN E2 to HIGH
GPIOE->DDR &= 0b11111011; // receivePIN E2 to INPUT (=0)
GPIOD->ODR &= 0b11111101; // sendPIN D1 to LOW
enableInterrupts();
for ( t = 0; t < 100; t++);

In = (GPIOE->IDR & GPIO_Pin_2);
while (In != 0) {
    In = (GPIOE->IDR & GPIO_Pin_2);
    total++;
}

In the image you can see the two pins, and you can see the blue one cannot reach the 3.3 V treshold, and it does not change much with aluminium foil touch.
Is there a better way to build a proximity sensor?
Thank you
EDIT 1:
This is my circuit, extremely simple:

Instead of clamp is attached the aluminium foil. I did use the 1x probe.
EDIT 2:
Ok, the probe was acting as voltage divider as you say. I also the function Delay that is connected to TIM4 in the STM8 I am using, event if I don't think it was actually a problem. I removed the probe and it works better. Actually the program works, but I can't have a good sensing range (looks to be 4-5 cms). Is there any way to increase the sensitivity? I tried reading the ADC after a defined and certain time, but it looks to have the same sensibility. Maybe it is the maximum? I Arduino and CapacitiveSensor I had a very long range (something like 20 cms)


texts: Issues related to multiplexed analog signals

texts:
I had an idea to transmitte a measured voltage of component X, from multiple slaves to one master device. Each slave's units would use the principle of time division multiplexing to set the data line to the corresponding analog level at a predetermined time and for a predetermined duration that the master unit would measure measure the line and separate the data. What kind of issue would I face doing this method rather than using a Data bus, or other serial interface.

The timings I'm considering are 100us cycles with a each device device holding the line for 5us and 5us gap.


texts: Understanding reverse biased PN junction

texts:
I'm trying to understand a reverse biased PN junction, conceptually. For reference, I'll adopt the convention that the P-type is on the left, and N-type is on the right. So without a bias, the depletion region forms and there should be a positive electric-potential step crossing from P to N. This potential step deters more holes from diffusing into the N side, and electrons from diffusing into the P side. I understand that applying a forward bias will reduce this barrier, allowing carriers to cross the junction quite easily.

So applying a reverse bias increases the potential step, making it even harder for holes to migrate to the right, and for holes to migrate to the left. But here's where my confusion comes in: who's asking them to? If the positive side of the voltage source is applied to the N-side, shouldn't the electron current be pointed left to right, and the hole-current be pointed right to left? In that case, the potential "step" should be a "downhill", which the carriers should be happy to cross.

So what am I missing here?

Edit

I think I figured it out, can anyone confirm that the following understanding is correct? The N-side could, in theory, provide the electron current, and the P-side could provide the hole current. but to complete the circuit, a electron current will need to flow out of the voltage source's anode, and all the way through the P-side. Electrons entering the P-side should be able to fill in holes in acceptors, and migrate towards the right as holes drift left. However, when the electrons get to the depletion region, all (or most) of the acceptors have already been filled by the electrons which diffused over from the N-side. So not only are there few (if any) holes left to be filled in the depletion region, but there is also a net negative charge there due to the acceptor ions, so there will be a force pushing back on the electrons anyway. I guess if any electrons manage to get past this wall of acceptor ions, then they would get to slide down the potential hill towards the n-side, but the issue is getting that far in the first place.


texts: Preferred way of interfacing relay coil with active low output from MCU

texts:
My prototype would use active low output from 8-10 ESP8266-12E GPIO pins to control AC appliances. I have several options to interface the relay (or SCR phase control circuit) with the MCU. But I can't decide which one is best to use from long term performance and cost perspective. What I have thought of so far, is as below:

Using a suitable PNP transistor:

simulate this circuit – Schematic created using CircuitLab

Using an optocoupler

simulate this circuit

Using darlington transistor array such as ULN2803

I have around 8 to 10 GPIO control pins. If I see from cost perspective, discrete transistors solution seems cheaper than those wired around optocoupler or ULN2803. However, I am not sure if all the hand soldering 8-10 transistors are worth the effort (I am no good at it, I admit). Also, I don't know how the discrete transistor based solution will perform in the long run. Any advice will be appreciated.


texts: Can this VCA bring output volume to zero?

texts:
I'm working on a synthesizer and trying to keep the VCA simple. I'm also trying to avoid LM13700s, partly because I want this to run on one 9V batter.

So I'm trying to make this design work:

My CV is about 2V peak-to-peak, and I've tried it with different center points. The result is quite linear but the problem is that the output volume never goes to zero!

I'm not sure if this circuit is capable of taking volume down all the way to zero. It seems like Q1 would have to have infinite resistance, or act like an open circuit.

Any thoughts? Any mods that would help me get planned silence into this output?

-James