texts: Electronic Drivers for Fluorescent Lamps: How is the DC-to-AC Conversion done?

texts:
Pretty much all (somewhat inaccurately named) electronic ballasts for fluorescent lamps run off a DC voltage and have to convert it into AC to operate the lamp.

The DC supply can come from rectified AC mains (as seen in standard compact fluorescent lamps) or from a low-voltage bus or battery (as seen in the interior lights of camping vehicles, laptop screen backlights or emergency lamps).

How are the circuits built that achieve the DC-to-AC conversion?


texts: Driving/dimming/strobing 30 pieces of Cree XR-E individually via Rispberry Pi 3, powered by 18v 4.0mAh makita accu

texts:
I am looking for a solution to individually dim (or if not possible switch) 30 Cree XR-E LEDs driven by a 18v 4.0Ah Makita battery and a step-down converter to go from 18v to 3,5v capable of handling about 120watts (total power when all LEDs are lit).

I'm thinking of using a Raspberry Pi 3, combined with a FadeCandy controller and a set of WS2811 drivers. Would this work? And how can I use the WS2811 chips to control high-power LEDs?


texts:
So I've been winding and unwinding, all to get the current right but it's not going well, so I'd like to know how I can limit the current going into the primary side of my transformer, since the winding ratio is 1:2, 160 turns on the primary side, and 320 on the secondary, I'm supplying 80v to the primary but the winding only has a resistance of 4ohms. I'd like to know how I can still be able to supply 80v to the primary and limit the current to 1 or 2 amps, to get 160v on the secondary. I am pretty sure the voltage will drop on the primary since the resistance is so small and I'm worried it will also make the output voltage less than what I need it to be...
I'm pretty sure a resistor in series with the primary winding will result in a voltage division? Which is also bad. I don't have much more wire to wind, can you please help me with a solution? Would a series resistor work?
Oh and the frequency is 60hz

Found this:
https://www.physicsforums.com/threads/mains-transformer-with-1-4-ohm-primary-winding.924900/

You can measure the inductance of the winding, but assume it is 10 henries. Reactance=2. * pi. * f * L
Pi=3.14159
F= 60 hz
L = 10 henries
So reactance = 2 * 3.14159 * 60 * 10 = 3769 ohms

So does this apply to a square wave 60hz alternating current supply?


texts: Optimizing dynamic range for acquisition of noisy signal

texts:
Is there a good rule of thumb for setting the gain of a noisy signal before digitization? Say I have a 16-bit ADC with a ±1V range; to what level should I amplify the noise floor of my signal relative to the resolution of the ADC.

This ADC has nominal resolution of 31μV and my hypothetical small signal lives in 100nVrms noise within the sampling bandwidth. How much amplification should I apply before the ADC so that I can increase my SNR through oversampling.


texts: why base Q11 is 0V current is flowing into the base of Q11, allowing current to flow between the collector and emitter.


texts:
new with code composer studio. Trying to run bldc motor with rm48 cncd. Lotsss of problems, one of them is any delay function available for ccs? I generate pwm signals with a certain delay using idle for loops. for loops do not work. Any help please?

Main()

{ // start of while loop

    Set_Duty_Period1.period=500;
    pwmSetSignal(hetRAM1, pwm0, Set_Duty_Period1);
    pwmStart(hetRAM1, pwm0); // pwm 0 is set for PWM_AH

    i=0;
    while(i<4000)
    {
       i++;
    }

    pwmSetSignal(hetRAM1, pwm5, Set_Duty_Period1);
    pwmStart(hetRAM1, pwm5); // pwm 5 is set for PWM_CL

    While(1)
    {

    }

} // termination of main


texts: Can two On-Off valves be independently or concurrently switched with my hardware?

texts:
I am having a ton of fogginess today thinking of a way to switch a couple On-Off valves with the hardware I'd like to use. When I say 'On-Off', I mean the valves pictured below, where applying voltage to the Open terminal opens it, and applying voltage to the Close terminal closes it. It will stop at any time (last position is the maintained position; I have other circuit components that will allow for this.)
I would like to use a 3-way (SP3T) selector switch to select which configuration to operate:
Valve 1, Valve 2, or BOTH.
I would like to use a single, momentary switch in the configuration of On-(Off)-On, or where the center is the normal state (off, nothing energized) and either side is momentarily energizing the OPEN or CLOSED motion of the Selected valve as mentioned above.
Is this even possible? I can't seem to wrap my brain around it today. I've done similar circuits before, but they had the benefit of hot (L) also being controllable with upstream logic, so in a way it was easier controlled.
UPDATE: Link to datasheet. (Pg6, Figure 1 is the particular wire diagram I'm referencing.)
Thanks


texts: Measurement of internal resistance of a battery

texts:
I found two circuits online of almost same approach to measure internal resistance of a battery. Both the methods excite the battery at 50Hz using a square wave and AC voltage drop is measured across the battery (as per my understanding). And apparently, this voltage drop corresponds to the internal resistance of the battery
Method 1: https://www.eeweb.com/internal-resistance-tester-for-batteries/
Method 2:
http://www.next.gr/meter-counter/Checker-Circuits/Internal-Resistance-Battery-Tester-l13989.html
In the method 1, it is mentioned that the voltage measured divided by 10 gives the internal resistance of the battery. And method 2 says, the internal resistance is 10 times the voltage measured. I request someone to please breakdown why it is so? What's happening in these circuits and what is the difference between them? And how reliable are these methods?


texts: What grounding should I use for this capacitively coupled input?

texts:
I'm designing a device that will receive and digitize analog video signals.  In analog video, it's recommended to capacitively couple inputs.  A typical input might look like this:

In this case the signal is on connector pin 2, then there is a termination resistor, and a capacitor connects the signal to the rest of the receiver.  DC current returns via connector pin 1 and the video cable.

Such a configuration is recommended by this Maxim app note (page 2) as well as various other places.  But none of them seem to discuss grounding.  It seems as though this app note (and others I have found) are trying to isolate the two devices, while also assuming they have a common reference!

The problem is that there's no obvious reference or return path back to the source for the signal that passes through the capacitor.  If the receiver (or the source, or both) were battery-powered and not connected to anything else, the whole electrical potential could float and follow the signal waveform and the ADC would see nothing.

It would be possible to connect the signal return (pin 1 of the connector) to the receiver's circuit ground, but this could create a ground loop, would defeat isolation among the connected devices, and would expose the receiver's ground to EMI/ESD coming through the connector.  It seems better to keep the cable isolated from the receiver's circuit ground.

So I think it might be necessary to include capacitor C2, as shown here:

Otherwise the AC signal passing through C1 might have to go all the way through the power mains, or some other undesired route, to return to the source.  So my question is whether capacitor C2 should be included in the circuit (and if so, what value it should have; I guess it should be large relative to C1), or if it is not necessary for some reason that I have missed, or if something else should be done instead.


texts: I'm starting a project where I want to use a BLDC motor as a generator. I understand that BLDC's need an ESC to be controlled. Essentially an ESC converts DC power into AC and provides the necessary timing to trigger the different phases of the motor. I was wondering, could an ESC be used to do the opposite? That is, convert AC into DC? Would this be correct? If not, could someone explain why and suggest a better way of achieving this? If I would take a guest, I need some kind of three-phase rectifier. I just want to understand why I can't use an ESC to achieve the same thing. Thanks.


texts: Two rf 433 transmiter and one receiver connection won't work?

texts:
This is my problem. I want to transmit from two transmitters and capture data with a single receiver. I bought two pairs of rf433 and  was able to transmit data between each of these rx-tx pairs correctly with ardunio.

But sending from two tx and receiving by one rx was unable to accomplish. Then I tried to find out the reason and here is what I found. These rx and tx modules wont work vice versa. See this diagram:

Since they both transmit 433Mz this also should work fine. If they work in vice versa only, I am able to transmit from two tx.

But I am unable to find out the reason behind this. I would be very thankful if anyone can help with this problem.

Thanks in advance.


texts: What is the most physically robust USB connector for PCB?

texts: Of the different types of USB connector that can be fitted to a PCB, which is the most physically robust type?


texts: Calculate difference equation from impulse response

texts:
Given the causal system with transfer function

$$
  H(z) = \frac{z^{-1} + \frac{1}{2} z^{-2}}{1-\frac{3}{5} z^{-1} + \frac{2}{25} z^{-2}}
$$

I can calculate the impulse response to be:

$$
  h[n] = \frac{25}{4} \delta[n] - \frac{35}{2} \left(\frac{1}{5}\right)^n u[n]
+ \frac{45}{4} \left(\frac{2}{5}\right)^n u[n]
$$

What is the constant coefficient difference equation relating input and output representing this system?

If I split out the three terms of the impulse function, I can calculate separate difference equations for each term separately, but I'm having trouble combining them back together. Maybe that is not the way to go?

Here is my work in that direction:

\begin{align*}
  y[n] &= h[n] * x[n] = \sum\limits_{k=-\infty}^\infty x[k] h[n-k] = \sum\limits_{k=-\infty}^\infty x[n-k] h[k] \\
  y_1[n] &= \frac{25}{4} x[n] \\
  y_2[n] &= \sum\limits_{k=-\infty}^\infty h_2[k] x[n-k] \\
  y_2[n] &= \frac{-35}{2} \sum\limits_{k=0}^\infty \left(\frac{1}{5}\right)^k x[n-k] \\
  y_2[n] &= \frac{-35}{2} x[n] + \frac{-35}{2} \sum\limits_{k=1}^\infty \left(\frac{1}{5}\right)^k x[n-k] \\
  y_2[n] &= \frac{-35}{2} x[n] + \frac{-35}{2} \sum\limits_{k=0}^\infty \left(\frac{1}{5}\right)^{k+1} x[n-(k+1)] \\
  y_2[n] &= \frac{-35}{2} x[n] + \frac{1}{5} \cdot \frac{-35}{2} \sum\limits_{k=0}^\infty \left(\frac{1}{5}\right)^k x[(n-1)-k] \\
  y_2[n] &= \frac{-35}{2} x[n] + \frac{1}{5} y_2[n-1] \\
  y_3[n] &= \frac{45}{4} x[n] + \frac{2}{5} y_3[n-1] \\
  y[n] &= \frac{25}{4} x[n] + \frac{-35}{2} x[n] + \frac{1}{5} y_2[n-1] + \frac{45}{4} x[n] + \frac{2}{5} y_3[n-1] \\
  y[n] &= \frac{1}{5} y_2[n-1] + \frac{2}{5} y_3[n-1] \\
  y[n-1] &= \frac{25}{4} x[n-1] + y_2[n-1] + y_3[n-1] \\
\end{align*}


texts:
My general question is why brushless DC motors seem to be much more expensive than similarly sized brushed permanent magnet motors, especially considering that the construction of the latter is more complicated?

In my concrete application, I'm looking for a brushless DC motor with a 10-15W max power rating. I was first looking for an alternator of that range, but this kind of product practically doesn't exist, I believe because a BLDC fills this role pretty well. Using a BLDC as a generator is a very attractive idea - since you're not driving it, you don't need to worry about ESCs, you just throw in a 3-phase rectifier and you're done (also, it's much easier to detect the running speed by detecting the zero crossings on one of the phases. And some BLDCs have Hall sensors as well, which makes it even easier). Comparing an in-runner BLDC to a brushed DC of similar size, you'd expect them to be practically the same in terms of construction, with the latter adding the brushes and the commutator - you'd expect it to be slightly more expensive. My research indicates that the reverse is true: a decent BLDC fetches upwards of $100 in most reputable electronics shops (e.g. Electrocraft in the UK), even in Alibaba they are $30+ (the price break for 100 units), and even RC-craft units optimized for onesies from eBay are $15-$20. Then you can definitely buy s very well machined japanese brushed motor (e.g., Mitsumi) for a few bucks.

Why is that? Are BLDCs still considered a novelty and economies of scale do not yet apply to them? Or am I missing some technical detail?


texts:
What will happen having only a DC source and a diode connected in reverse?

Will the diode or the source overheat over time or something bad might happen if you let it operate like that?


texts: Trouble finding the R(equivalent) in this circuit

texts:
I started studying Electric Circuits one week ago so this material is new to me. I was trying to solve this problem from the book but I had some difficulty:

My analysis:

The equivalent resistance R1 for parallel resistors 16Ω and 48Ω is 12Ω (16x48/16+48).

The equivalent resistance R2 for parallel resistors 24Ω and 12Ω is 8Ω (24x12/24+12).

The equivalent resistance R3 for resistors in series R2 and 22Ω is 30Ω (8+22).

The equivalent resistance R4 for parallel resistors R3 and 45Ω is 18Ω (30x45/30+45).

The equivalent resistance Rab for resistors in series R1 and 18Ω is 30Ω (12+18).

Why is the final answer 34Ω? Mine got 30Ω.


texts:
I see these values written on inductor symbols on the schematic of an RF filter/PA, what to make of these values?

a) what does "4T1.5D*0.31" means?

b) what does "CM" means in this expression "1uH/CM"?

c) what does "CI" means in this expression "1uH/CI"?


texts: What could cause unexplained brownout resets?

texts:
Context

I'm building a 7kW bidirectional two-stage switching converter. Each stage has its own control board and processor. The entire system runs off a common 24V rail.

Isolation stage

Two H-bridges on either side of a transformer, running at 18 kHz, 50% duty cycle, both sides switching. Big dumb isolator, no regulation. Processor just feeds the pulse widths, phases them in on startup, and provides appropriate delay across the transformer. Running a dsPIC 30F4013, 5V rail from a switching regulator.

Regulation stage

Two IGBTs in series, running at 12 kHz. If the lower switches, it boosts out of the isolation stage. If the upper switches, it bucks into the isolation stage. Running a dsPIC 33EP128MC506, 3.3V rail off a switching regulator.

The mystery

In boost mode, the entire system works fine, no problems across the entire power range. In buck mode, I get processor resets when the system reaches about half rated current. Specifically, the isolation stage processor resets pretty consistently when I reach a particular current range. (It's definitely current-related. If I tell my control software to limit the current, and keep raising the input voltage, I get no faults.) If I alter the configuration bits, moving the brownout detect level from 4.5V to 2.0V, this processor stops resetting. This strongly indicates to me that the processor is resetting due to brownout. RCON register contents are consistent with this as cause of reset.

So now I can raise the current further, However, when I do, the regulation stage processor now starts to reset! That particular processor doesn't have any way to alter the brownout level, but it's a reasonable assumption that's the cause. RCON register is again consistent with brownout as cause of reset.

So I've got two processors resetting as a response to how much current is running through my converter, but only in one direction. It's reasonable to guess that both are resetting on brownout, due to some shared environmental factor. I've tried disconnecting all common points between them, disconnecting the down-stream H-bridge drive, and rerouting some cables. Nothing I've described changes. The only things both processors still have in common are their common power rail, and physical proximity.

Scope shows no deviation on the logic power rails. There's some 18 kHz noise, but that's there even if I connect both ends of the scope probe to the common test point. Otherwise, the rails look great. I've got .1 uF multilayer ceramic caps at every power input to both processors, and a 100 uF tantalum also immediately adjacent. Increasing these capacitances has thus far had no effect. Both circuit boards are two-layer, with a copper area tied to common on the bottom layer directly under each processor. (Processor is defined as being on the top layer, so there's circuit board material in between.)

All I can think to try is some sort of physical rearrangement involving shielding the processors from the power components. Does anyone have other suggestions?


texts: Capacitive-load derating for bridge rectifier

texts:
I'm confused about the precise meaning of the derating info/graph for capacitive loads for the Visahy 2KBPxxM-M4.

I get it that the current rating for capacitive loads is less than for resistive/inductive, but what are the precise conditions for the bottom 3 curves, i.e. how should I read the "equation" or wahtever that is that I encircled with red?


texts: Understanding an 'ideal' diode made from a p-channel MOSFET and PNP transistors

texts:
The Raspberry Pi B+ models have a protection circuit between the USB connector and the 5V net on the board.  They recommend putting a similar protection circuity on a Pi HAT before 'backpowering' the pi through its GPIO header along with a polyfuse.  I understand why this is the recommendation, but I'd like to understand more about how this circuit works.

I did some searching before posting this question and found information on using a MOSFET as a low voltage drop diode, but they all had the gate wired directly to ground without the pair of PNP's and the resistors.  What are they doing for this circuit?  Also, is this primarily using the body diode?  In which case, what's the relevant info on the datasheet that qualifies DMG2305UX for this application?  In the other circuits I found, it appeared low Rdson and Vgsth compatible with the circuit seemed like the relevant characteristics.


texts: Inaccuracy and mismatch of integrals in LTspice

texts:
I calculated the energy dissipation of a load R1 in a simple circuit within a duration of 1 second using two methods.

Using an arbitrary behaviour current source to integrate the product of current and voltage applied to the load R1. Reading the final value of the corresponding trace gives the Energy \$E_a\$.
Plotting the power over the load R1. Afterwards selecting the trace with Strg + Left Click which shows the integral of the trace \$E_t\$.

The circuit that was simulated in LTspice XVII:

\$E_a\$ and \$E_t\$ give different results. \$E_a\$ was always more accurate than \$E_t\$ for several combinations of frequency and amplitude of the sinusodial voltage source B1. When B1 is set to be a DC source there are no errors. Here are some of the results:

f= 10Hz  Amplitude = 1  \$E\$ = 0.25 J
\$E_a\$ [J] 0.249999
\$E_t\$ [J] 0.248911
f= 50Hz  Amplitude = 1  \$E\$ = 0.25 J
\$E_a\$ [J] 0.24999225
\$E_t\$ [J] 0.23473
f= 10kHz  Amplitude = 1  \$E\$ = 0.25 J
\$E_a\$ [J] 0.184319
\$E_t\$ [J] 0.14374
f= 10kHz  Amplitude = 10  \$E\$ = 25 J
\$E_a\$ [J] 24.6539
\$E_t\$ [J] 24.059

As can be seen increasing the frequency increases the error compared to the actual value \$E\$ as well as the difference between \$E_a\$ and \$E_t\$.
Increasing the amplitude reduces the error at a given frequency.

So why do I get different results at all? As a discrete integration equals a summation of \$P_i\cdot\Delta t_i\$ at each timestep, I suspect that \$E_t\$ is calculated with larger timesteps leading to less resolution.

There is also the problem of reduced accuracy at higher frequency. How can I avoid this? For the given circuit this could be circumvented by only calculating a single period and scaling to the duration afterwards. But I am more concerned about more complex circuits where it can take some time until a steady state is reached (and would not notice this error).

Source Code:

Version 4
SHEET 1 880 680
WIRE 112 112 16 112
WIRE 208 112 112 112
WIRE 496 112 352 112
WIRE 608 112 496 112
WIRE 16 128 16 112
WIRE 208 128 208 112
WIRE 352 128 352 112
WIRE 608 128 608 112
WIRE 16 240 16 208
WIRE 208 240 208 208
WIRE 208 240 16 240
WIRE 352 240 352 208
WIRE 480 240 352 240
WIRE 608 240 608 208
WIRE 608 240 480 240
WIRE 208 256 208 240
WIRE 480 256 480 240
FLAG 112 112 u1
FLAG 208 256 0
FLAG 480 256 0
FLAG 496 112 u2
SYMBOL bv 16 112 R0
WINDOW 3 -109 153 Left 2
SYMATTR Value V= sin(2*pi*time* 10)
SYMATTR InstName B1
SYMBOL res 192 112 R0
SYMATTR InstName R1
SYMATTR Value 2
SYMBOL bi2 352 128 R0
SYMATTR InstName B3
SYMATTR Value I= idt(V(u1)*I(R1))
SYMBOL res 592 112 R0
SYMATTR InstName R2
SYMATTR Value 1
TEXT 272 296 Left 2 !.tran 0 1 0


texts: Is there any point to having a power plane for a single device?

texts:
Let's say I have a power supply that is powering only a single sensitive opamp. That opamp only has a single power and ground pin.
Is there any point to having a power plane for that power supply, or would it be sufficient to have a fat power trace leading to the device and its bypass caps?


texts: LDR connect to opamp switch very fast when low battery

texts:
I use LDR connect to opamp like this circuit.

I use input is 5V from 7805 connect to battery 12V.
When relay turn on the light about 2 hour then relay switch on and off continue very fast. How to fix it?


texts: Mosfets get Very hot at relatively low power drop(As E load)

texts:
I'm trying to build my own E load according to the circuit I made here:

Now not having a thermal lab and very good understanding at how it suppose to work with the thermodynamics but when I set the output load to 10V 2A 20W the 2 beefy mosfets I've connected in parallel(only 2 mosfets and not 4 like in the schematic) the E load block gets very hot to the touch to a point where it is it's limit and they are connected to quite a big heat sink.
Mosfet used:
IXFH75N10 TO-247
And the question it:
Is that normal?
I came across a few E loads on aliexpress which seem to have around 5 time's the performance (Mosfet amount and heat sink size counted) like those:
E load 75W no heat sink
E load 250W
ELoad 60W with heatsink
Can't understand why.


texts: Basic question is: Is it permissable / safe to connect a $10 plug in timer relay with potential for backfeed from a second source?  20 watt fan being switched.  This is a SIMPLE question, compared to those I see here. Hope you won't laugh too hard!


texts:
I know how to plot the Fourier transform, but is there a more precise way to measure the total harmonic distortion?

I have this graph:

As you see, there's only one distinguishable component at 1 kHz which is what I want. I need a THD less than 5% . Is the ThD zero here?


texts: Design a tank circuit for class C power amplifier using ADS

texts:
I am trying to figure out the best values for the tank circuit values (L and C) in order to compare the amplifier's efficiency with the output power
I have chosen the tank value L1 and C7 to resonate at 1GHz (see attached), you know we can choose different values for L and C to be resonating at the 1 GHz frequency. What is the most efficient way of selecting the L and C values for such a case?


texts:
I bought the following dipole antenna:

Now I want to add some extra simple reflector and directors next to this dipole to construct a Yagi-Uda antenna. For this aim, I need to know where is its feeding point (its center for a dipole antenna ). Eventualy I removed the cover of the antenna as follows:

My question is that where is the feeding point of this antenna In this last figure? Is it as in the following figure? If it's not, could you show it?

By the way, the antenna link is here : with an NRF24L01 Module


texts:
Trying to upload programm from Arduino IDE to ESP-WROOM-02 according description.

I tried to enter program mode by following procedure below:

Press both the RESET button and PROGRAM Button together.
Leave the RESET button alone and keep Pressing the PROGRAM button for 1 more second.
Leave the PROGRAM Button, now you are in UART Download mode.

But my Arduino IDE reported:

the selected serial port _
 does not exist or your board is not connected

I was trying to connect terminal to serial port and I found array of bytes issued after pressing reset. I was trying to record these bytes by using different communication speed:

9600:
22 19 36 86 96 79 83 19 87
19200:
A1 09 42 C2 EB 0A 0B C2 A3 D5 28 99 AD E1 54 FB
38400:
62 84 A4 64 E4 84 86 85 A4 A6 85 A4 84 85 A7 86 E5 87 C4 87 E4 A6 A6 46 43 A3 C4 C4 A7 A4 A7 C4 A7 44 F3
57600:
47 01 C4 5A 06 98 51 05 40 40 48 64 49 95 77 0B CC 51 3B 6B 43 50 40 E6 6F 0B D4 57 5A 35 B5 46 99 14 44 54 5B 63 9B 6D 0A C8 57 06 D0 57 86 0B F1

What might be wrong in my system? What kind of information module is trying to send me?


texts:
I have ONE n-to-1 multiplexer and I'm trying to assign its n input ports from another component which has n output ports. How can I do this?

My code is given  below, and the errors.
I've ommitted the other component to avoid confusion.

Errors:

Unknown identifier "i".
Individually associated formal "mux_in" must be identified with a locally static name.
Actual (indexed name) for formal "mux_in" is not a static signal name.

Code:

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

package data_array is
CONSTANT Block_Size      : integer := 64;
CONSTANT Entry_length  : integer := 32;
type signal_array is array(Block_Size downto 0) of std_logic_vector (Entry_length-1 downto 0);
end package data_array;

library ieee;
use ieee.std_logic_1164.all;

library work;
USE work.data_array.all; --including the package

entity A is

generic (
  Block_Size    : integer := 64;
  Entry_length  : integer := 32
  );

  port(
    sel:            in integer;
    new_entry:      in std_logic_vector(Entry_length-1 downto 0);
    clk:            in std_logic;
    reset:          in std_logic;
    done:           out std_logic;                             --indicates completion of shifting
    last_entry:     out std_logic_vector(Entry_length-1 downto 0)
   );

end A;

architecture Synchronous of A is

    Component Multiplexer

      generic (
        Block_Size    : integer := 64;
        Entry_length  : integer := 32
        );

      port(
        sel:        in integer;
        mux_in:     in signal_array;
        Mux_out:    out std_logic_vector(Entry_length-1 downto 0)
         );

    end component;

  --Intermediate signals

   signal interconnect : signal_array;
   signal temp_entry : std_logic_vector(Entry_length-1 downto 0);

  begin

  temp_entry <= new_entry;

      --Instantiating the mux
           mux: Multiplexer
                generic map(
                  Block_Size     => Block_Size,
                  Entry_length => Entry_length
                  )

                port map(
                  sel        => sel,
                  mux_in(i)  => interconnect(i),
                  Mux_out    => temp_entry
                   );

 end Synchronous;


texts: STM32405 ADC on Update Event of Timer 1 or 8

texts:
I'm not sure what I should be asking for because some of the terminology is confusing to me, but what I'm trying to do is use the two motor timers (TIM1 and TIM8) on the STM32F405 to sample BEMF on a sensorless BLDC driver.

On a previous version of this hardware, I was using an F411 and only driving one motor, so what I was doing was the following:

Set up the hardware timer PWM outputs of TIM1 to drive the gate driver (CH1,
CH1N, CH2, CH2N, CH3 CH3N)
Set up the timer to run at 20kHz and change the duty cycle using a PI controller.  PWM is driven using Center Aligned Mode 3.
Set up CH4 of TIM1 to count to 1.  Use this event to trigger an ADC injected conversion of the 3 BEMF resistors.

This works OK, albeit rather hackey....I know that's not right, but it was working.

However, now that I'm trying to drive two motors with two different motor timers, I can't lean on this same method because I'm not allowed to sample more than 4 injected conversions at a time....What is the right way to use two motor timers to drive two independent BLDC motors and grab the required 6 BEMF signals at the top of the center aligned PWM signal?


texts: Why are there so many vias on this board?

texts:
I was looking at the MMZ09312BT1 development board layout, and I was curious about all the holes they have on the board. Are these vias? What is their purpose (I heard somewhere that they are meant as a filter)?

Also it doesn't say explicitly, but is it possible to tell if they have a ground plane on the bottom layer?

Datasheet: http://cache.freescale.com/files/rf_if/doc/data_sheet/MMZ09312B.pdf

Development board on page 8


texts: Understanding constant current/constant voltage charging of LiIon battery

texts:
I'm trying to understand exactly how CC/CV charging of a LiIon battery works and I tried to replicate it with a cheap bench power supply (RD Tech DPS3003) and a Samsung INR 18650-25R. The bench power supply is capable of both CC and CV. Here is what I tried:

Discharge the cell to 3.1V
Set the bench power supply CV to 4.2V according to the battery data sheet
Also set the PSU CC to 1.250A or 0.5C, according to the data sheet
Connect the PSU's positive lead to the battery's positive terminal; same for negative

What I thought would happen:

The PSU will supply as much voltage as necessary to make the set CC of 1.250A flow into the cell
As soon as the cell voltage reaches the set CV of 4.2V, the PSU switches to CV mode and the current will decrease steadily

This is what I saw instead:

When I measured the voltage at the battery terminals while charging, the voltage went up only a little, to around 3.3xV and slowly rising as the battery charges
The PSU display shows around the same voltage and only a current of around 530mA
The PSU displays that it's in CV mode, rather than CC mode.

Clearly my understanding was wrong and I'd love to understand better. Why did I not see the set CC of 1.250A? Were my settings wrong, e.g. do I have to allow for a higher voltage? But then how will the PSU limit the cell voltage to 4.2V and switch to CV mode later? Or could it be that my cheap bench power supply does not behave as it should?

Additional information: I also did a quick check with my Liitokala Li500 battery charger. I set it to charge the same battery (by then at around 3.3V cell voltage) with 1A and measured the voltage at the contacts. It was around 3.5V. Unfortunately I could not easily measure the current. I'd be very glad for any insights on how my understanding was wrong.


texts:
I have an arduino with a simple 3-pin IR receiver like you would find at radio shack. The receiver works fine when the power supply to the arduino is 6 AA batteries, but not when the power supply is a wall plug with 7.5V DC. It seems to work for a few seconds, then not at all. I'm using the IRRemote library here: http://www.arcfn.com/2009/08/multi-protocol-infrared-remote-library.html

To further help describe the problem, the Arduino is controlling a bunch of LEDs, and when I use PWM to turn down the brightness of these LEDs, the IR receiver ceases to work as well, either when battery powered or wall powered. When the PWM is not being used and the LEDs are full on, it's not a problem.

I'm not sure how to debug or fix this. I'm sure that the IRRemote is using a different timer than the PWM, and the power source exhibiting the problem when the PWM is off confirms that that's not the root cause. I suspect that there may be some kind of noise introduced by the wall power supply or the rapid switching of the LEDs. Both the receiver and all of the LEDs are tied to the same ground pin of the Arduino. What can I do to separate or filter the receiver so that it is not affected by the power supply or PWM?


texts: I need to understand the flow of this circuit well. The objective of this circuit is to switch the latching relay "OFF" or "ON" (in two states) depending on the state of the I/O's of the MCU. I need to understand how this works. The relay is a 9VDC, 60A, 250VAC relay, and the bridge gives an output of 12Vdc. Thanks!


texts:
When compensating switch mode power supplies we usually use IC that incorporates error amplifiers, but sometimes there are ICs that come up without internal error amplifiers and so we can either use TL431 or an external OP AMP for compensation.

My question is when TL431 is recommended over an OP AMP ?

As far as I know OP AMP are more flexible than TL431 for designing a compensation loop and this is due to the incorporated pole of TL431, but beside this drawback, TL431 is widely used specially in flyback topology.


texts: Professor said my embedded system design is incorrect, what did I get wrong?

texts:
The problem:

Your embedded system has an 8-bit microprocessor, which has a 16-bit address bus. In addition, you have a 32-Kbyte FLASH chip, and a 8 KByte RAM chip. You want to locate the FLASH chip right in the beginning of the address space and the RAM at the end of the address space. All the memory chips have a single /CS selection line, which is controlled by a fast 32 x 8 OTP-ROM chip.

What are you going to program into the contents of the OTP-ROM, and how do you connect it to the microprocessor and the memory chips?

I got only 1.5p out of 6 points by using a solution similar to the picture I attached. The prof told me the following:

"you got one point for the correct OTP-ROM circuit outputs connection and ½ points for connecting address lines a15 and a14 to OTP-ROM circuit. Other than that, the connection was wrong, and the contents of memory were not given/solved at all."

Please help me in this problem. Any advices are appreciated.

From where should I start? And what I should program into the opt-rom? A 32x8 matrix full of ones and zeros?

block diagram of the opt-rom (see the below.):

my attempted (wrong) solution:


texts: 24V DC to 5V for powering a Raspberry Pi 4 and a router for a vehicle - what should i use? DC/DC converter?

texts:
I am looking for a DC/DC converter from 24V to 5V for powering 2 devices
So this is what I got:

A vehicle power box that will give off 24V -- This is my power supply

A Raspberry Pi 4 Model B (Max USB draw = 1.2 A)

A router ADVANTECH ICR-1601G (The original power supply outputs 5V 2A)

If anyone has any recommendations and/or solutions for use in a vehicle, it would be much appreciated.
Currently, I'm thinking that a DC/DC converter would be the easiest solution, but I've not found something that gives off enough current.
Thanks!


texts:
What is the main difference between a mosfet transistor and a BJT transistor.

I know both are used for amplification and can be used as switches.

But where would you use one over the other and what are the benefits of each one ?


texts:
I made a post a while ago about having large excursions when reading from my MAX6675. Despite using adum5401 digital isolator to float the MAX6675  as suggested in the original post, I still see a lot of noise on the MAX6675 thermocouple input using a scope.

I did notice on the MAX6675 board there's only one bypass cap on the the VCC rail. There is absolutely no filtering on the thermocouple input.

Large excursions in thermocouple readings with MAX6675

Questions:
1) Can I apply some filtering on there?

2) I read on a different forum that the thermocouple amp should ideally be connected to analogue GND and that the AVR microcontrollers don't have any. By using a ADUM5401 to float the MAX6675, have I effectively created an analogue GND? If so, it's still no go.

Any help would be very much appreciated!


texts: PCB Schematic Question: Is it necessary to include the antenna for the bluetooth IC? (Making my own Arduino Nano clone)

texts:
I'm trying to make my own customized version of the Arduino Nano 33 IoT. I noticed in the Arduino circuit schematic, there is an antenna specified, and it connects to the Bluetooth unit as if it's an external component. However, when I look up the Bluetooth device used (NINA W102), the antenna is already included in the NINA module. In fact, when I'm looking at the NinaW102, I can see the antenna already attached to the top of it.

My question is, am I correct in assuming that I DO NOT need to specify the antenna in my schematic, since the Nina module already includes one? This is my first PCB design I'm sending to a manufacturer and I want to make sure to get it right. Thank you!

Arduino Nano schematic PDF

Arduino Nano spec page

Nina W102 Datasheet


texts: Photo-conductivity of n and p type semiconductors

texts:
Both n-type and p-type semiconductors are available to fabricate a
  photoconductive devices. To achieve the highest photoconductivity, do
  you want to use n-type or p-type? Why?

$$σ_{ph}=q(μ_n ∆n+μ_p ∆p);\ \ \ Where\ \mu_n>\mu_p$$

The answer is supposedly p-type but wouldn't the mobility of an electron be higher in a n-type semiconductor than in a p-type semiconductor? Which would mean photoconductivity of a n-type semiconductor would be more?


texts: How does this timer 555 and transistor circuit work?

texts:
Is this the way this circuit works ?

If vref = 5v on the pin #5, then Vthreshold = 5v, and Vtrigger = 2.5v

With Vthreshold = 5v, if voltage on pin #6 Vp6 > 5v, then Vp3 is Vo = 0

With Vtrigger = 2.5v, if voltage on pin #2 Vp2 < 2.5v, then Vp3 is Vo = Vcc

The transistor works as a current source, giving:
Ic = 15,089mA

Does the capacitor start to charge when the trigger activates in t = T/2, meaning that Vc = 0
until Vp2 < 2.5v ?
While the capacitor is charging, Vo = Vcc ?
And then when the voltage on the capacitor hits the Vc = Vthreshold = 5v, discharges and Vo = 0 ?
Does it work like this ?
NOTE: The max voltage of Vo is VCC - 1.5v, not 5v like in the picture.


texts: Confusion with the DC response of an RC integrator

texts:
Below is the beginning section from a tutorial on filters:

  An integrator (Figure 1a) is the simplest filter mathematically, and
  it forms the building block for most modern integrated filters.
  Consider what we know intuitively about an integrator. If you apply a
  DC signal at the input (i.e., zero frequency), the output will
  describe a linear ramp that grows in amplitude until limited by the
  power supplies. Ignoring that limitation, the response of an
  integrator at zero frequency is infinite, which means that it has a
  pole at zero frequency. (A pole exists at any frequency for which the
  transfer function's value becomes infinite.

Can you explain what is meant by "the response of an integrator at zero frequency is infinite, which means that it has a pole at zero frequency."?
What does it mean the response to be infinite? And what does the term pole represent here?

Edit:

In this document there's a plot for s = jw+sigma. But if s has sigma component, doesn't that mean a damped oscillation? I can understand that for steady state the plot of freq. response is independent of time. But damped input is time dependent and not periodic but yet they can plot it as if it is time independent in that 3D plot for RC passive filter.

3D plot for s=jω+sigma there is still a point on the surface. So surface point at s=jω+sigma is not the same point with s=jω. I can understand s=jω is a sinusoidal input's frequency and has a fixed amplitude over time(time independent) but what is s=jω+sigma? If it is damped oscillation, how can it even be plotted on a surface which is time independent?

hen I look at s = jw axis(when sigma is zero) and for example when jw=628j which is f= 100Hz the vertical axis form that point on that 3D surface will be the response of the filter. This is the amplitude of the steady state response. So we have steady state input output like in Fourier. Now imagine s=jω+sigma = 628j+10. This is not a steady state input, and the vertical axis form that point on that surface will have a single value. But the response should be damped. So what is that value of the damped response on the surface? Is that the max amplitude or the mean value of the damped response?


texts: GY-521 MPU-6050 + Arduino nano - Logic converter or not?

texts:
I bought this MPU-6050: link (marked as "GY-521" on the board)

According to the manufacturers' site, the sensor logic level is 3.3V (though the eBay page says Power supply :3-5v)

Should I use a 4 channel Bi-Directional Logic Level Converter (like this one) for the SDA, SCL, INT channels? or can I connect it directly to my Arduino Nano?

I saw some places that says I should use it with a logic level converter and some who say it's ok without it. (I guess it depends on the sensor board, so please take a look, link above)

Current Setup:

SDA <-> LLC <-> A4
SCL <-> LLC <-> A5
INT <-> LLC <-> D2
VCC <- LLC <- 5V (arduino)
GND <- LLC <- GND (arduino)

I still don't have the parts so I can't test it, and I'm probably going to use Jeff Rowberg library to communicate with the sensor (I2C)


texts: How do I find the return loss of a transformer from its 4-port S-parameter data?

texts:
I'm looking for information on the performance of Mini-Circuits
T16-1-KK81+ transformer. The transformer is well-characterized, Mini-Circuits provided both insertion/return loss charts and raw S-parameter measurements for download.

I'm having difficulties on reproducing the official return loss chart using the raw S-parameters.

It's a 4-port VNA measurement with 16 S-parameters, the s4p file says,

!Model: T16-1
!Run/Lot/Date Code: MW42300//0640
!DATA FOR: UNIT#1
!Fixture/SN/Due: 90-2-20-233/72223/07-24-2009
!Connection: PORT-1 - pin<4>; PORT-2 - pin<6>; PORT-3- pin<3>; PORT-4 - pin<1>;
!PORT EXTENSION DONE ON TEST FIXTURE WITH LOSS ON AND MISMATCH ON

The primary dot is Pin 4, or port 1, so the return loss should be a plot of S11, but the plot looks like this,

In no way it resembles the official return loss curve,

I thought the script I used to plot the chart was broken, but I don't see obvious issues in my code. I suppose the difference is due to the termination. I guess the VNA measurements were done with four 50Ω ports, but the return loss chart in the datasheet assumes a matched 800Ω load, is it correct?

How should I proceed to reproduce the return loss chart?


texts:
I am designing a 50 ohm 10 watts dummy load for 100-1000MHz frequency range. The signal strength should not exceed -10dBm.
The load must be able to dissipate 5 watts minimum, that is +37dBm.
The output to the test equipment must be no more than -10dBm.
So I need an attenuation of 47dB but to make it easy lets say 50dB.

The load consist of two 5W-100ohms resistors. After the load as you can see in the schematic picture there is 3 different attenuators. The first one is 20dB attenuator for 5W dissipation, second one is 20dB-50mW dissipation and the last one is 10dB-50mW dissipation. You can see the values of the resistors on the schematic picture.

Specification for the PCB board:

Trace thickness : 0.036mm

Substrate height : 0.8mm

Trace Width : 1.5mm for 50ohms and 0.3 mm for 100 ohms.

Substrate Dielectric : 4.3

One thing that I couldn't figure out here is the width of the tracks when routing the attenuators as you can see some of them routed with a narrow line. Should it be as thick as 50ohms or something different considering the values, I don't know this because I have never seen it before.
Long story short I need help with the circuit and routing the microstrip to have a good impedance match.

Looking forward to hear my mistakes and your suggestions about it. Thank you

EDIT

I tried to change the circuit as advised and designed the PCB layout, not sure if its the way to do it.


texts: Why does an induction motor draw more current when the load is increased?

texts:
I am aware that a coil has inductive reactance when powered by AC besides the еlectrical resistance which is typically very low.

Considering the fact that reactance is proprotional to the inductance and supply frequency, how is that related to the load of the motor?

Let's assume the following parameters:

inductance 0.5 H
resistance 5 ohms
AC Supply 220V/50Hz

Further calculations show that the impedance is about 162 ohms. According to Ohm's law the current flow would be 220 volts divided by 162 ohms = 1,35 A no-load current. Now I want to understand what exactly changes in the equations above that makes the stator windings draw more current when the rotor is opposed.


texts:
I have been looking for some time for a good design for a ~10MHz sine wave generator, with variable frequency from about 5-20MHz. The max required peak to peak amplitude is 10V. Many suggestions on the internet include using DDS such as AD9833, however, that feels like overkill for what I need. I have also seen a similar question to this, however, their application requires an extremely wideband (1-200MHz).

I am using this as a Local Oscillator, which I am mixing with an error signal.

Preferably, I would like to use a simple, cheap circuit design involving op-amps, with <5% distortion. However if there is a better design, I am all ears.


texts: Replace a trimmer potentiometer with a thumbwheel (rotary) potentiometer

texts: I am trying to make an LED strip dimmer circuit using LM2596 Buck converter, but the trimmer pot  makes it difficult to change the brightness every time. Is there any way to replace the trimmer pot with a rotary pot , if so then what wattage and resistance should I keep in mind in buying the appropriate rotary pot ?


texts: Using HD44780 display without contrast potentiometer

texts:
I found tutorial about connecting HD44780 display to Raspberry Pi.

In this tutorial there is no contrast potentiometer. Vo is connected to ground.

Tutorial author says:

  In order to control the contrast you can adjust the voltage presented
  to Pin 3. This must be between 0 and 5V. I tied this pin to ground.

Is this common and correct way to use this display?

I never seen that before (Vo connected to GND).

Link to tutorial


texts: What is the simplest method to simulate a solar panel on a current/ voltage regulated PSU?

texts:
Solar panels have a typical non-linear I/V relation. The figure below shows an example of such relation. What is the simplest method to simulate this relation with some current or voltage regulated power supplies and minimum component count?

The simulator will be used to test Maximum power point trackers. I found this circuit, but I'm looking for a simpler solution. I'm looking for a cheap solution.


texts: Is the input impedance of an operational amplifier (op amp) infinite or zero?

texts:
Ideally, the input impedance is infinite.

But, in calculating the input resistance (Rin) of a difference amplifier, the author took the concept that the two input terminals are short circuited, which is also true, since the open loop gain is infinite. (Which in turn demands that the difference between the input terminal voltages is zero. Hence, short circuit.)

MY Question:
Why is that we consider zero input current in few cases (owing to infinite input impedance), and sometimes consider finite current taking the short circuit concept? Is there a logic or is it just a convenience?

This is the snipped out circuit diagram from the book:


texts: I want to do AC RMS measurement. The input signal is derived from the utility power line, so it's frequency not so stable. So i want to use PLL to synchronize the ADC sample pulses to the input signal. Use PLL to generate N pulse per cycle, then route these pulses to ADC. Is this possible?


texts: Lattice ispLSI CLPD dump/transfer hex file

texts:
I have two boards that contain Lattice ISPLSI1016-60LT44, one is dead in short circuit (is is very hot when powered also), one is on working condition. Even though this part is discontinued by the manufacturer, there is still some in stock around the world. I have found official programmers named HW-USBN-2A (also discontinued) and a newer HW-USBN-2B (still supported). There are a lot of clones of the former at eBay.
Atmel (Microchip) AVR devices contain lock-bits that can prevent dumping the hex file (you can only erase the whole chip if they are set in the right way). However, if not set, you can dump hex from the working one and burn it into the fresh one.
If I replace the damaged part with the new one and use the HW-USBN-2A eBay clone, would I be able to perform the repair? I did not order anything yet and I would like to calculate the price needed for diagnosis and eventual repair.
EDIT
I have found in the programming documentation that there is a thing called Security Cell, which I believe is the equivalent of the fuse lock-bits.
What is the easiest/fastest way to check if the Security Cell is enabled (thus preventing the code trasnfer) ?


texts:
I'm trying to build a simple water level detector using BC557 PNP transistor (there's already a similar question here but doesn't solve my problem...)
Circuit 1 below is what I'm thinking to build based on the standard biasing of PNP circuits (Circuit 2) as there's only 1 power source available. However, without a power source to reverse bias Emitter, I'm not able to have a Collector current. I think I'm doing something wrong here as it should work based on this for example. I can simulate an emitter current in Circuit 1 but no matter what resistors I use on the Emitter end (using 20k and 200k here) I cannot get a Collector current. Any idea what I'm doing wrong? This is my simulation.


texts: How to manage solar panel as backup power source

texts:
I have a 12V PC cooling fan (Evercool PWR-1225H12B) that will run on a 12V regulated supply. Said supply is on a 12 hour daily timer.
In addition to the timed supply, I want to have a solar panel as a backup supply.

The fan draws about 450mA (personally measured) at 12V, full speed. The panel is only 6V (4.5W), but is enough to spin the fan decently.

I'm considering different ways of managing the two power inputs. I have read that solar panels should not be subjected to reverse current, as they may overheat.

Below is a basic "OR" diode setup. I chose the 1N5821 Schottky because it was rated for 3A and had what I think is a fairly low voltage drop of 0.38V @ 1A. Is that a good choice? When the 12V supply is open, the panel's current is simulated at 227mA. There would be about a 300mV drop across the solar panel's diode, thus about 69mW of wasted energy.

When both supplies are on, the reverse current on the panel is simulated at 645μA, so I think the panel will be fine. Obviously a fan as a load is not just resistor, but because there is a bunch of driving circuitry inside it, I wasn't sure how else to represent it unless I just stick a random inductor in there.

The next circuit is another setup I've seen that uses a PFET. I was thinking that perhaps this would be slightly more efficient for the solar panel, as the FET might have less drop than the diode. This of course depends on which diode and FET I compare. I wasn't sure which PFET to use, so I just entered a beta of 50m and a threshold of -2V. That results in a solar current of 237mA when the 12V supply is open.

Simulations are only so useful. Those above were only using ideal components. I would use ltspice, but I don't have correct SPICE models for the fan or diodes and FETs, so I didn't bother. This is why I'm wondering if anyone has advice on about the pros and cons of different configurations in the real world.


texts:
What is a good SNR for a medical device like a pulse oximeter?
Is there a U.S. Federal standard for this?
Thanks!


texts:
I'm trying to do an AM modulation  using band pass filter at the output the carrier is at 600 kHz and the message signal is at 1.5 kHz. To get a 100% modulation I did some calculations to get fL=598.5 kHz which I think is the LSB frequency and fH= 601.5 kHz the USB. My questions are:

1- Are the calculated values of fL and fH correct?
Given that Vm=10 Vp-p and Vc= 5 Vp-p, what is the modulated AM signal
output Vp-p should be?
In this circuit I think the modulation is slightly below 100%, what do I
need to do to make it at 100%?
The message signal doesn't seem to be synchronized with the AM signal how can I correct that.
In the second circuit I used a parallel LC band pass filter which gives a 100% modulation but the output voltage is in micro volts, how can I amplify the output voltage without effecting the modulation if it does?


texts: Are Germanium Zener diodes still obtainable?

texts: I need a Germanium Zener diode for a shot noise generator circuit. If I am correct, Silicon replaced Germanium for use in diodes and other semiconductors because of the fact that Germanium diodes have a much higher reverse leakage and are much noisier. But due to the smaller band gap of Germanium as compared to Silicon, this makes them more useful in shot noise generators since at the Zener voltage, a Germanium Zener diode has a depletion region that is smaller than the electron wavelength and as electrons tunnel through it, their energy levels spread out due to the uncertainty principle.


texts: How calculate the error offset or the noise threshold for MyoWare and FSR sensors?

texts: I am working on EMG and FMG signals to extract time domine features and i need a threshold value for some features. I must calculate it from the characteristics of MyoWare and FSR sensors.For the MyoWare sensor i concluded that it is the error offset from the CMRR.The MyoWare has as CMRR:110,Adjustable Gain Potentiometer:50 kΩ,Input Impedance:110 GΩ and VIN=5v.How can i calculate the error offset? and i still stucked in the threshold of the FSR sensor.Can anyone help me?


texts: Mitigate TPS56* ecomode ripple effect under lighter loads

texts:
Following my question Powering up analog part of the video card (thanks everyone for their inputs and advices) I have chosen the devices, and even have drawn the circuit diagram of 12 V to 5 V power converter:

Output current is expected to be approx 250 mA, maximum 500 mA.

I was very happy, until I found the following article, which made me very upset. It is in Russian, but I translate key points.

The TPS562200 is having some serious drawbacks:

Causing it to physically burn if layout is not followed - in particular there must be no switching current under the chip. Good to know before routing the board.
Vias are required as VBST and SW pins are put at the different sides of the chip. Also good to know.
Very high ripple under low load.

The last one seems actually being killing the whole design. According to calculations, the current when device goes into Advanced Eco-Mode Control mode (datasheet, chapter 7.3.2, page 12) if load consumes less than 500 mA => in my device the regulator will always be in this mode.

Article considers this case with very demonstrative pictures:

Above is an output for the "nominal" operating conditions.

Above is an output for the 200 mA supply current. Ripple frequency is 65 kHz.

Above is an output for the 50 mA supply current. Ripple frequency is 1.2 kHz.

This noise would be a huge issue for the analog circuits. I see two ways to deal with it:

change regulator with one rated for smaller current - for example, TPS560200, then "The transition point to the light load operation" will happen at 230 mA. However I suspect most of the times less current will be consumed from the supply, and it may easily happen that switcher will work in this featured ecomode.
Keep this ADP3339 High Accuracy, Ultralow IQ, 1.5 A, anyCAP Low Dropout Regulator. It has very nice ripple rejection property:

and this ripple under 100 kHz is expected to be attenuated greatly.

Questions:

Is this ripple effect will take place under "lighter" loads for any switcher, or it is a "feature" of these TPS ones?

Do you think the design is acceptable for powering analog video circuits - would selected LDO cure the issue created by the TPS?

Maybe you can propose something better than I have drafted?

Update:

following Marcus's advice I tried Webench (previously I was using it in relation to TPS562200 only). I set requirements of 12 Vin, 6 Vout, max current 0.5A, and nominal current of 0.2A... and have got 53 results, one of them is this TPS562200!

I forgot one of the requirements I have: chips must be solderable by hand by not-so-experienced individual. Thus most appropriate packages are SO or SOT.


texts: A Series-parallel circuit combination with current as input source

texts:
I am asked to find:
1.) the voltage drop |V|
2.) Current i1
3.) Current i2

So far I only managed to find the total resistance and total voltage which is 6 ohms and 72 volts respectively. I am really confused on where to start or what to find first. Can anyone help me with this? Thanks


texts:
Suppose I want wo measure how strong someone (or somthing) pulls on a rope, i.e. I want to measure the tension (=dragging) force on the rope.
The pulling would come from only one direction.
I assume a maximum force of let´s say about 1000N (could be more, but let´s forget about the exact range for now).

What would be a reasonably priced method?
I searched a bit on the web and found lots of force sensors which should do the job, just one example out of many would be , e.g.

https://www.burster.de/de/produkte/p/detail/8417/

Now, as far as I can see, this part has "just" some resistance strain gauge(s?) with a wheatsone bridge incorporated. Nevertheless, It is priced at about 800 EUR per piece, something I cannot afford.

I thought about building an own setup, i.e. sticking discrete strain wire gauges to some kind of cylinder. Of course the question arises which material to use for the cyclinder.

Can someone share experiences in building "custom" strain gauges for such a scenario?
Maybe resistance strain gauges are even a bad idea, maybe an LVDT (Linear Variable Differential Transformer) in combination with a spring would be better suited?

EDIT: The solution should be small enough to be integrated in some kind of handheld device (let´s assume a box of 20 x 5 cm) Environmental protection such as IP5X is not needed since ideally, the solution can get some kind of enclosure later on.

Thanks!


texts:
I'm just learning to use the PIC microcontrollers and am totally confused having no knowledge prior. I am using a pickit 3 and the DSPIC30F2010. I  have used to connect them via the circuit as shown below(i made it myself after lot of digging, couldn't find something that works in the internet). The thing is I am not even sure if the circuit is correct, primarily because i to had power the chip externally via 5V since the pickit seems to unable to power the chip by its own(returing errors like unable to detect VDD),but that kind of feels not normal, i mean the pickit should naturally be able to power the device right?

Despite my assumptions, the processor was detected and i was able to write programs into it, although when i click the verify option in the mplab IPE, it sometimes says 'verify failed' and other times, it is fine. Is this normal?
The program i wrote was generated using MICRO C FOR DSPIC and the generated hex file was written via the MPLAB IPE.
The program i used was obtained online. Its a program for simply blinking an LED.

//i have used crystal of 16 MHz

void main()
{
TRISE.F0=0;
  while (1)
  {
    PORTE.F0=1;
    Delay_ms(1000);
    PORTE.F0=0;
    Delay_ms(1000);

  }
}

But as i understand you can only write programs via the pickit, however you would require another circuit(using an external clock and so) to actually test the program.
please help me with this. What would be the circuit required to essentially test the program i written.


texts: Why does LT spice limits frequency domain output to 65535 data points?

texts:
Background:
I ran a simulation and I am generating the S21 gain of a circuit I am working with dembedding and wanted a 100% accurate and wanted a ridiculous amount of data points and when checking my simulation error log it states that the "Number of points reduced from 100000000 to 65535."

Attempted fixes: Up to date 64bit
I have updated to the newest 64 bit of ltspice and looked through the control pannel, but I don't know why the .ac simulation of the circuit is limited to that many points or how to fix it. I can export .trans with a million data points just having an issue with .AC.

Error Message:
Number of points reduced from 100000000 to 65535.

spice netlist if desired

* \\my_network_location\
R1 N002 0 10k
R2 N003 0 10k
R3 out 0 50
C1 N002 0 1p
C2 N003 0 1p
C3 out 0 1p
L1 N002 N001 1p
L2 N003 N002 1p
L3 out N003 1p
V1 N001 0 PULSE(0 1 0 100p 100p 400p 1000p) AC 1
;tran 0 10n 0 0.01p
.ac lin 100000000 1 10000g
;tran 0 20n 0 0.01p
;.ac lin 1000000 1 100g
.save V(out)
.backanno
.end


texts:
When making a simple led circuit I should add a resistor to make sure the current does not exceed what the led supports. Should I put resistors in a simple circuit with a motor? with a chip?

The main question is: Is there a general rule to know when a resistor should be added?


texts: A circuit to fade-in and -out LEDs (DRLs) only when the car engine is running?

texts:
I would like to make a small hobby project to implement in my car.
However, I would like to ask here as I do not have much experience with electronics.

Let's suppose that I have a switch which should turn on or off the daytime running lights (DRL) of the vehicle.
These are separately installed and are consuming ~0,8 A from the battery (14,4 V when charged).

I would like to achieve the following effect (we assume that the ignition is turned on):

when I close the switch and the engine is not running, the DRLs are off;
when I close the switch and the engine is running, the DRLs are gradually turned on (fade-in for about 5 seconds (configurable));
when I open the switch or the engine stops running, the DRLs are gradually turned off (fade-out for about 5 seconds (configurable)).

To me, it should be something like this:

simulate this circuit – Schematic created using CircuitLab

I think the schematic can get information whether the engine is running via:

a voltage comparator - preferable, as it should be simple enough. If the car battery voltage V1 is above a certain (configurable) threshold, e.g., 13,3 V, then turn the rest of the schematic on;
an inductive tachometer - shall be a bit harder and comprehensive to install.

Perhaps a time delay relay may also be used, but would not be very suitable as it wouldn't detect the engine stopping.

As possible solutions for the fade-in/fade-out effect, I though of a BJT with a RC (integrating) circuit to set the time constant. Nevertheless, perhaps the losses would be lower if a (MOS)FET is used because of the ~10W LEDs.
I also read that a 555 in monostable mode would be suitable.

It is important that the transistor is positioned "high-side", i.e., it opens or closes the 12 V supply to the DRLs. Their negative pole is connected to ground (chassis) and the positive is currently fed through the simple on-off switch SW1.

Preferably, the solution should be as simple and inexpensive as possible, i.e., no Arduinos or microcontrollers if feasible :)

Thank you in advance!


texts: Total equivalent resistance of this circuit

texts:
All resistance are equal in value, \$R1 = R3 = R4 = R5 = R6 = 1~\Omega\$

My calculations are as follows:

R1 and R3 are in parallel => \$R13 = 2~\Omega\$
R5 and R6 are also in parallel => \$R56 = 2~\Omega\$
R13, R4 and R56 are in a series => \$R_s = 5~\Omega\$
\$R_{eq} = \dfrac{1}{R_s} = \dfrac{1}{5} = 0.2~\Omega\$

I am getting a total resistance equal to \$0.2~\Omega\$, but my teacher said that the correct answer is \$\dfrac{1}{4} = 0.25~\Omega\$. What am I doing wrong?


texts:
I have a cabin which is running off grid, using a solar panel and a (2*120 Ah 12V) battery.

I now want power in another building 20 meters away. One solution is to use an expensive high gauge (7 mm2)cable, to reduce the voltage drop - but that cable is also much more difficult to hide. I can't bury it without tripling the length.

I will have a bigger battery bank in the other building eventually, but the solar panels will remain on the main building.

When the voltage drops in the cable, is that also wasted Watt-hours? A few lamps will happily run on fewer volts. I am more worried about losing Wh's.

What other alternatives do I have?


texts:
I want to have a sensor to let me know if a door is locked or not. I've placed two wires inside the lock mechanism of the door, so when the door is locked the continuity test on the multimeter make a sound, if is unlocked it doesn't make a sound (no continuity).

I've tried to replicate that with a NodeMCU. I have follow the same example as a push button,

3V3 -> BUTON Pin 1 |-| Button Pin 2 -> 10k Ohms -> GND
                                    -> D7 (Digital 7 GPIO)

simulate this circuit – Schematic created using CircuitLab

This works fine with the switch button, but when I replace the switch button with the wires on the door, nothing happen.

I checked the Ohms on both cases, the switch on rest have 10M Ohms, and when pressed have 0.4 Ohms.

The door when is closed have continuity with 16 Ohms, when is open it doesn't have anything (no continuity, no ohms, open circuit).

What I am missing here ? Another question, if a person touch the door (has metal on it) it can catch a spark or anything ? It's safe ?

The final goal is mimic the behaviour of the multimeter.

EDIT: Looks like some alligator cables I was using were in a bad shape. I've replaced but still it doesn't work. After checking everything and trying again, it is WORKING!

I will try to start solder some cable to proper connect each other without using alligators.

Video with this working: https://youtu.be/a3UFyRAJedA
Cables: https://imgur.com/a/2ByPSY6


texts: can you have a system with multiple anodes connected to one cathode (e.g.Battery, generator, biocell, solar cell)?

texts:
simulate this circuit – Schematic created using CircuitLab
Usually, the anode transfers electrons to the cathode. However, let's say the anode is not releasing enough electrons to create enough current for a certain application. Can I have multiple anodes (same type) connected to one cathode to generate more current?
if possible, How can I calculate the voltage and the current?


texts:
May I ask your comments on the layout below? Specially the via under the MCP16322. The layout is still missing the connector for the in/out voltages, but would love to have your opinion at this point.

Added after I read the answers:
So much thankful for the great answers below and made changes accordingly. Will you please let me know what you think. Please don't mind the unrouted test points.

Iteration 3. Added after reading Abdullah's answer:
I couldn't get rid of one of the two traces cutting thru the ground. Tried to make it shorter. Is it not good to have it go underneath the chip?

Schematics:


texts: Sanity check: Input and output filter for a stacked pair of DC/DC converters

texts:
In my current project, I need voltages of +/- 30V and +/- 15V for analog control purposes. The current on the 30V rails is fairly limited, ca. 70mA max on one rail and <10mA on the other. The 15V rails will only see <5mA.

I couldn't find a (reasonably priced) converter to generate +/- 30V directly, so I now plan to stack two +/- 15V DC/DC converters. However, I read that stacking converters this way will increase the need for external filtering, so I tried to figure out how to go about that.

Here is my current schematic:

The DC/DC converters are TEL-3 0523 from Traco Power. I selected them because of their good regulation and constant current limiting, which helps in my application.

The schottky diodes at the outputs are supposed to protect the converters from reverse voltage, in the case where one or the other converter would turn on more quickly.

The capacitors are all Panasonic FR series low ESR types, specifically EEUFR1H121L for the 120µF, EEUFR1V271L for 270µF and EEUFR1C471 for 470µF. The ferrite beads are all high-current types from Würth Elektronik (this one for the outputs, this one for the input). LTSpice simulation shows that the output ferrite together with the 120uF capacitor make a very well damped LC filter due to their parasitic resistances, with a -3dB point at ~6kHz and almost -50dB at the 300kHz switching frequency of the regulator.

The common mode noise (between input and output, due to capacitive coupling) will be conducted through the ground connection.

Is this filter OK? Should I add ceramic capacitors in parallel to the aluminum electrolytic caps, or should those be fast enough? LTSpice simulation suggests that adding 10nF with a series resistance of 15 Ohms would improve the response in the high megahertz range, but at that frequency I don't really trust the simulation anymore because so many parasitic effects become important.

Finally, will my ground plane become noisy from the high frequency return currents (mostly via C6, and between the converter outputs and inputs), and can/should I try to do something about that?


texts: 8085;Condition CALL Instruction: if condition fails

texts:
In call instruction there are 5 machine cycles S,R,R,W,W (S is 6 T-states opcode fetch) and thus 18 T-states
In first machine cycle, t1-t4 is utilized for fetching the opcode and decoding it and t5-t6 is used for decrementing the Stack pointer to facilitate pushing of higher byte of PC onto stack in 4th machine cycle .
Now in conditional CALL instructions there are also 5 machine cycles S,R,R,W,W
The T-states are given as 9-18
So if condition fails only first two machine cycles are executed .
Therefore 2nd machine cycle is used for checking the flags in addition to being used for reading from memory .
My question is that if condition fails , then first two machine cycles are executed , which means that in first machine cycle SP will be decremented by 1  but nothing will be pushed as only half of instruction is executed
Won't this create incorrect operation of stack ?


texts: Do I need a diode to protect my ESP32 from a connected relay?

texts:
My ESP32 is controlling a relay which I switch on for 500ms (controlled through the internet).

Do I need a diode to protect my ESP32 from voltage spikes when the magnetic flux collapses?

I'm using an ESP-WROOM-32, and the relay specs are (taken from here):

  Small and light weight.Specifications:- Contact form: SPST normally
  open- Coil Resistance: 1050ohms- Nom Volts: 12 - Pickup Voltage: 8.4V
  DC- Rated Current: 11.4mA - Allowable Voltage: 160%- Dropout Voltage:
  1.2V DC - Carry Current = 500mA.- Power Consumption (W): 0.1 - Contact Rating: 1A- 12 VOLT

I've been using it without any problems for quite a few days, but I'm wondering if there's a chance it could be damaged randomly, or if there's something in the ESP32 pins that protects it from things like this.

Here's a circuit diagram of my setup:


texts: in host to device communication protocol, what does high and low mean?

texts:
I'm trying to learn about the PS/2 protocol from here. At about 4:00 he talks about low and high values.

This part is to let the host send data to the device but the clock should come from the device.

My question is what is zero, what is one and what is z (high impedance) in this context?

Meaning; when he says "high" or "release the clock" for example, does he mean one or Z? (I'm thinking Z)


texts: How do I remove this power supply noise?

texts:
Above is the circuit diagram of my power supply. It converts input 12V DC into 5V DC and then 3.3V DC with linear regulator. I have highlighted it in red color in the block diagram.
So current situation is, whatever noise is there on 12V input voltage shows up on 5V and 3.3V. how do I filter this? How do I improve my design to get clean 5V and 3.3V even with a noisy 12V input.
If I use clean power supply 12v, I am getting best results. But i can't give 12V clean power supply to everyone. Customers can pick up any noisy power supply and it should work with my design.
Below I am attaching two waveforms , Yellow is 12V , Blue is 5V and Pink is 3.3V.

this is zoomed out view

Zoomed in view
If you look at the waveforms, the noise appearing on 12V is carried on to the 3.3V. I was assuming LDO will at least attenuate it more but, it is very high. On the PCB the ground is properly stitched with multiple vias from top to bottom.
How do I get rid of this, what do I have to change or add in my design to improve it?
Note: Input 12V Dc power supply used is a 220V AC to 12V DC adapter.


texts: What's the purpose of traces that are later punched out?

texts:
I've found this odd feature on an FPC in a Camera than handles button and switch input.

You can see there are traces that look like they were once connected and later punched out to be cut. The one on the left once short-cut a button, which would have the same effect as if the button was pressed all the time.

Here you can see the other components involved. The Button on the right is a two-stage button, the other trace leads to the Anode (yes, Anode, not Cathode) of an LED.

I've never seen something like that, what were those traces used for before they were punched out? Are those commonly used for testing parts of a circuit? Could they be a manufacturing or layout error that had to be fixed later on?


texts:
I've made a few electronic devices, and most of them had buttons or switches, but I had to rely on my memory to remember which button did what.

What kind of hardware options are out there for labeling switches and buttons other than masking tape and ink pen?  Do they make switches with text on them?  What about those silicon cover masks?


texts:
Is it possible to make FBus to USB?

Does it need any complex circuit?


texts: Resonannt frequency of resonant current converter DC/AC

texts:
I have to work with this topology of resonant current converter, and I want to clarify some points:

T1 is a transformer that I should specify to designer
LT is a tuning inductance
T2 is a transformer made with a wire (one winding in primary) passing through different magnetic cores of different devices. Each device has its own number of winding. All devices use a rectifier and a voltage refrence to made a DC voltage source.

Is it correct to simplify the circuit as I did with one transformer passing through the one equivalent magnetic core to provide equivalent DC voltage source?

The second point, is related to the resonant frequency. What is the equivalent impedance seen on the primary side of the transformer T1? Some article simplify the circuit as bellow:

Is this correct to consider Lp (primary inductance with secondary open) since the secondary load of T1 is LT with a wire loop. This simplification doesn't take into account leakage inductances.


texts: Designing stand-alone microcontroller based components

texts:
3 Years after finishing my study of computer science (B.Sc.) my search for a new hobby lead me back to the microcontrollers. There were 2 semester microcontroller programming  with embedded assembler in C on a ATMEL development board. But I really hated it.

Now I want to give it a second chance. During the years I found some practical use cases and I have some ideas.

But my first question, after researching for dev boards is: how do I port my application from the development board to a stand-alone unit? Do I have to buy single parts and solder them on a board? Or can I buy ready to use components for a single purpose (e.g. switching a motor time controlled).

edit: there were many nice answers which helped me a lot researching about the topic.

As the question got marked as "put on hold - too broad": I wanted to know if I have to solder cheap units or if there exist cheap ready-to-run components to implement a few small applications without buying a relative expensive dev board for each application. I already isolated 3 candidates to buy. Thanks you all for your answers.


texts: Is power DC power supply ground, connected to the chassis earth on a desktop PC?

texts:
When I plug a data-acquisition PCI card to a PC, I'm trying to picture the ground connections. Some following confusion arises:

Is the PC motherboard's ground and PCI's ground common?
Does a PC have analog and digital grounds? Ore one common ground?
If so, is this PC common connected to the chassis earth as well?


texts: Using the ATMega328 with the internal oscillator?

texts:
I have a project that I think would be best suited for an ATMega328P. However, in every simple project I've seen, people always hook up a 16MHz external oscillator. From what I can see, it should have an 8MHz internal oscillator. My project doesn't require a lot of processing power, nor does timing need to be very precise(other than for a UART and I2C). I have a programmer also, so I don't need to worry about bootloaders.

Is there any reason for me to use an external oscillator?


texts: How to convert PDF to Gerber for PCB layout?

texts: I've got a PDF file with a PCB layout I'de like to produce - however, I need the file in Gerber format first. Is there an easy way to convert between the two? I've found this: https://swannman.wordpress.com/projects/pdf2gerb/ - does anyone have some experience with it? Does it work well? Are there better alternatives?


texts: Driving a 7 Segment Display with a register vs wire

texts:
I few days ago when I got my FPGA I created a module to drive my 7-Segment display.  I used only continuous assignments to drive the leds.

module set_number(input [3:0] x, output [6:0] seg);
    assign seg = x == 0 ? 7'b1000000 :
                 x == 1 ? 7'b1111001 :
                 x == 2 ? 7'b0100100 :
                 x == 3 ? 7'b0110000 :
                 x == 4 ? 7'b0011001 :
                 x == 5 ? 7'b0010010 :
                 x == 6 ? 7'b0000010 :
                 x == 7 ? 7'b1111000 :
                 x == 8 ? 7'b0000000 :
                 x == 9 ? 7'b0010000 :
                          7'b1111111;
endmodule

I was reading a book and they have a 7-Seg display written like this using registers and a combinational always block.

module hex_to_sseg
(
 input  wire  [3:0]  hex,
 input  wire  dp,
 output  reg  [7:0]  sseg   // output active low
);

always @*
begin
   case(hex)
      4'h0:  sseg[6:0]  = 7'b0000001;
      4'h1:  sseg[6:0]  = 7'b1001111;
      4'h2:  sseg[6:0]  = 7'b0010010;
      4'h3:  sseg[6:0]  = 7'b0000110;
      4'h4:  sseg[6:0]  = 7'b1001100;
      4'h5:  sseg[6:0]  = 7'b0100100;
      4'h6:  sseg[6:0]  = 7'b0100000;
      4'h7:  sseg[6:0]  = 7'b0001111;
      4'h8:  sseg[6:0]  = 7'b0000000;
      4'h9:  sseg[6:0]  = 7'b0000100;
      4'ha:  sseg[6:0]  = 7'b0001000;
      4'hb:  sseg[6:0]  = 7'b1100000;
      4'hc:  sseg[6:0]  = 7'b0110001;
      4'hd:  sseg[6:0]  = 7'b1000010;
      4'he:  sseg[6:0]  = 7'b0110000;
      default:  sseg[6:0]  = 7'b0111000;   //4'hf
  endcase
  sseg[7] = dp;

Is there any practical difference between my approach with the wire and the book's approach with the register and combinational logic?


texts: Two stage op-amp design with compensation ideas

texts:
I am trying to design an op-amp with a high-pass feedback. The diagram is shown below. The high pass feedback has a corner frequency at 1Hz.

The op-amp itself is two stage as can be seen below.

Based on the books that I have been reading and the number of designs I have found online, the procedure that is generally used involves taking the compensation capacitor into account from the get go. In all of those designs, we assume we want a phase margin > 62 degrees and come up with a value for the compensation capacitor. My question is, how would a high-pass filter in the negative feedback path affect the choice of compensation capacitance needed? In all the designs I've seen, the compensation capacitance was taken to be 0.22*CL (0.22 to meet the phase margin requirements). Should the addition of a high pass filter affect this calculation and if so, how ?

Here is the other question: I have only about 55A to play with based on the power requirements. In other to meet the required GBW, I need about 17A in the branch that contains M1 and M3. I would naturally just mirror this current to the branch containing M2 and M4. However, this would the current in this branch 34A leaving only about 20A for the second branch which is too little. The second branch should consume the highest amount of current. The only way I can reduce the current in the middle branch is by mirroring only a fraction of 17A into the branch containing M2 and M4. This makes things very hard because it would implying that M1 and M2 (and also M3 and M4) are no longer of the same sizes. Based on the number of designs I've seen, M1 and M2 (and also M3 and M4) are always of the same sizes. This seems to imply that something is quite wrong. I wouldn't mind some assistance if possible.


texts: What is the difference between programing with JTAG and USART interfaces?

texts:
I understand there are 2 interfaces to programming NanoMind A712 computer: JTAG and USART. But what is the difference in programming the computer in JTAG or USART interfaces?

Datasheet: See page 10: "The NanoMind computer is equipped with a diagnostics interface enabling software upload to the on-board code storage and interaction with the computer via a simple console-like debugging screen."


texts:
Hey all,
I'm fiddling with a breadboard to make some logic gates and instead of buying spst switches, I bought dpdt switches because they were the only ones that would fit in the board.  :/

Can I somehow use these dpdt switches as inputs in my logic gate?


texts:
I would like to create a power supply for a learning project, using either a DC adapter or a 9v battery.

I've read a few topics here and on the web about barrel connectors, but I'm still not sure how to use it properly in conjunction with a battery.

The schematics and articles I found are unfortunately too vague for my poor understanding, so I made one.
Is this the correct way to wire the battery to a barrel connector, so I can use one or the other?

Edit

Battery will be 9v, DC adapter will certainly be 12v.

Ideally, I would like to be able to keep the battery in place while using the DC adapter. Battery will then just be bypassed.


texts:
I have a problem with Altium fanout.
I can not use fanout with my BGA processor (AM335x,) but fanout is working on DDR3 and eMMC.
I did the same things with DDR3 and the processor but fanout for the processor did not work.
You can see the screenshot of my problem.
Can someone help me?


texts: ZigBee Light Link and XBee interoperability

texts:
With the release of new products like Philips Hue, which claim to support ZigBee Light Link, I would be interested if there is any way to use existing Xbee modules to communicate with them?

Would it be possible to create a network using Digi's Xbee modules (series 2) and communicate with the bulbs/lights or is a custom firmware required? (which I do not think that exists at the moment for Xbee modules).

If not, is there any drop-in replacement for Xbee to be able to communicate with the Light Link devices?


texts: Difference between using a first order low pass filter and a second order

texts:
So I have the following schematic. Basically what it does is , first it has an oscillator that produces a triangular wave (not from op amp output , but by taking a wire after the capacitor C1) . After that we have a band pass filter that is used to take the high frequencies and the DC offset from the signal , so we produce an AC sine wave. My question is for the third part(the red highlighted one) . I am asked to use a second order low pass filter like the one in the schematic. Why is that , why wouldn't I use a first order low pass filter , is there a difference in the wave if we use a first order low pass filter instead of a second order?

Εdit: I looked up the wikipedia entry which states:" The Bode plot for this type of filter resembles that of a first-order filter, except that it falls off more quickly." Can this be explained using the Xc (capacitive reactance) and solving the circuit?


texts: Drive a DC motor as the maximum speed with a Raspberry PI

texts:
I am new to the Raspberry PI and I don't have strong background in electricity (but I'm here to learn).
The problem:
I have a dc motor that works at 12V, and I'm trying to let it run with the raspi through a motor driver based on M51660L IC. I control the motor driver with the gpio PWM. I know that I need the motor driver because otherwise I can damage the pi. I can power the pi both with the USB cable from a computer and with a 5V power supply (I'd prefer to use the power supply and not the USB from the computer). For the PWM I used the python code from this blog post.
The problem is that, even if in the code I set the low PWM duty cycle the motor runs slow.
I think that the problem is that the PWM out from the pi is at 3.3V, while it should be 5V.
Trials
If I attach the motor directly to the 12V power supply (without the pi), it goes faster (and I want it to go fast).
I tried to connect the 12V directly to the motor driver, and the motor driver was suddenly gets very hot, so I disconnect it, because I think that the motor driver can handle till 6V.
I have also a Darlington Array ULN2003A, but I'm not sure if I can use it (as far as I understood it can be used for switching the motor direction only).
The question:
Is my idea true? The motor does not get the maximum speed because I should drive the motor driver with 5V instead of 3.3V?
What can I do? I'd like to spend as less as possible because I have already spend more then I thought to drive a DC motor from the pi (I bought the motor, the motor driver and the Darlington array).


texts:
I have a problem with the capacitance value change in bus with some wires when I touch it by hand.

I don't know if the change is because of the leakage current and how to solve this problem to have the fix capacitance value.


texts: Is this an elegant approach for a simple, debounced tank level controller?

texts:
I am interfacing some industrial (24v) process control equipment to some new projects in the embedded realm of electronics (3.3/5V small signal) and am coming up with some simple solutions for controlling a valve with an existing sensor.

The level sensor is a 4-20mA 2-wire transducer, so I was considering just terminating it to a practical level (1-5V) then using that as the inverted input to an inverted schmitt trigger in order to provide a debounced output to a solenoid through an nFET. I know there are also specialized SR latch IC's that do this in smaller packaging, etc. Didn't know if there were some other tried and true ideas out there that would perform better that are more minimal. Is the use of zeners recommended? I was thinking I could use some kind of selector knob to modify Rf to change the H/L SP gaps.

Thanks

Thoughts on the size of Rf?
Thoughts on my Vhyst band?
Would zeners, if available in the voltage desired, be a better plan? Are those part tolerances usually better? While my transducer isn't usually too noisy, the setpoints are rather specific, so I'm envisioning this or some fairly expensive .01%tol parts. The resistor values themselves seem to get a little dicey at 28.37k; I am willing to do a series combination I suppose.
One thing I am curious about is if I wanted to add a selector knob to "drastically" change the thresholds to one of many possible combinations, does that rule out this circuit for practical use? I'm sure I could feed the Vouts of 10 of these triggers independently into a 10-p switch, but that might feel like a bit much. And it feels like a far cry achieving specific thresholds like that by potting out just one of the resistors in the circuit.


texts:
Why is  inductive reactive power  considered positive while capacitive reactive power is considered negative in the circuit ?

Both inductor and capacitor consume apparent          power so I guess total reactive power in the circuit should be written as.

Total reactive power = Total inductive reactive power + Total capacitive reactive power.

but in books it is

Total reactive power = Total inductive reactive power - Total capacitive reactive power.Is this because energy oscillates between the inducter and the capacitor?

I do not understand this. Can anyone help me on this ?

Could you say why the sign is negative for Capacitor whereas this also store energy inform of charges and Inductor also stores energy in magnetic form. Then why Capacitor -ve and Inductor is Positive ??

Anyone can give a good analogy to understand this concept ?


texts:
I am running micropython 1.14 (happens also on 1.9) on the NUCLEO-H743ZI dev board (compiled using the board definition in micropython, no further changes) connected to a W5500 shield.
The issue I am seeing is some kind of delay when sending UDP packets and also when just pinging the board.
The ping goes from 1ms to 200ms and it seems to be cycling (like there is some fixed polling or something), going down and up:

Connecting the same shield to Arduino Uno yields the correct behavior, ping is 0.2ms:


texts:
What will happen if the drain voltage in the below image increases up to 200V? (the Mosfet could be IRF9640 or could be p-ch mosfet in IRF7105) I want to know if the Mosfet temperature goes up and also if the Drain current
is almost zero.


texts: Calculation of a voltage in the frequency domain

texts:
The current generator provides a constant current \$I\$ and the circuit is at règime conditions. At \$t=0\$, the switch T is being closed.

I have to calculate the voltage \$v_c(t)\$ by using the Laplace (unilateral) transform.

simulate this circuit – Schematic created using CircuitLab

After having calculated the initial condition (at \$t=0^-\$) \$I_0\$ and \$V_0\$, I can draw the circuit in the frequency domain, calculate \$V_c(s)\$ and antitrasform to get \$v_c(t)\$.

simulate this circuit

In the above circuit \$R_1\$ doesn't appear because it's shortcircuited, but why \$I\$ doesn't appear too?
Could anybody explain-me just this, please?


texts: Why does my PMDC motor have spikes in its BEMF?

texts:
I have two identical PMDC motors.  I ran each of them on a dyno at the same voltage and the same load.  They both consumed the same amount of current, yet one of them runs 300 RPM slower.

The one that is running slower was actually under test for several hundred hours, while the faster one is brand new.  Wondering if there's something going on with the brush/com, I put each motor in a motoring dyno to check their BEMF (both motors were driven with the same speed).  Not sure what I was looking for, just hoping to see a difference.  The graph is below.  The blue trace is from the motor that runs slower.  There are obvious voltage spikes that the other motor doesn't have.  Is this the reason for the motor running slow?  If so, why?


texts: Lower sound from 1st input when second input has sound

texts:
I'm looking for an IC/device/... that can switch between sound inputs.
Lets say that I play music through audio jack 1, and a GPS is connected to audio jack 2. I'd like the IC/device to lower/kill the audio coming from jack 1 and play the gps sound (being the voice commands by the GPS) from jack 2. When the GPS is done speaking, the music should start playing again after some time.

Is there such a device/switch/ic/...? Does the concept described above have a name?

Thanks in advance.


texts: How to best "synchronize" image producer/consumer to handle different FPS?

texts:
I'm building a system that among other things has an imaging sensor spitting out digital video @ 30 fps and a display system that displays to a monitor @ 60 fps.  The system currently utilizes a frame buffer controller that I've implemented in an FPGA and off chip memory.  The reader (monitor) reads from the buffer at will and the writer (camera) pumps data into the buffer at will (it's a fully asynchronous controller).  There's enough memory to store a few frames of data.  The system works fine.  I can display the video feed from the camera on a monitor without a hitch.

The issue that I'm facing is that the reader/writer have different clock rates/resolutions and, therefore, different fps.  What this implies is that at some point the monitor displays data from the current imaging frame, but because it consumes data faster than the camera produces data "out runs" the camera and starts displaying data from a stale camera frame.  This is OK provided that the camera doesn't move really quickly or that the same scene is imaged over and over.  If, however, the camera moves rapidly or something in the scene moves rapidly (e.g. things in the scene move faster than the camera sampling rate) then it's clear that the current frame will be substantially different from the previous frame.  That means that the monitor can display portions of both frames at the same time, which manifests itself in a line "moving" down the screen.

So -- getting to my question -- I'm wondering what's the best way to solve this problem.  The monitor and camera have two independent clocks, which are asynchronous to each other.  I have control (I generate) the pixel clock for the monitor, but the camera pixel clock is 100% asynchronous to the system (it comes out of a deserializer IC).  A few more details: the FPGA is clocked at 100 MHz from an oscillator.  I use a DCM inside to generate the 40 MHz pixel clock for the monitor and have several other pieces of the system running at 100MHz.  The camera pixel clock is about 13 MHz (but can go up to 27 MHz).  The camera FPS is generally stuck at 30 FPS, but can go slower depending on exposure control.

I could do something like always display the same frame twice so that the monitor is doing 60 fps, but 30 distinct frames/second.  That would work OK, but if I ever change the camera frame rate to something arbitrary that doesn't divide nicely into 60 then I'm out of luck.  Maybe more importantly if I change my monitor fps this works poorly.  As a more robust extension of this idea I could think of ways to only display "whole frames".  In other words don't start reading a new image frame until it's entirely written (or more robustly until you know that you won't over run the camera on that frame).  This would mean that not every image frame gets the same number of display frames, but maybe that's OK.

Any suggestions?  How do commercial systems typically handle this problem?  In particular how do USB cameras handle this?  That seems like a pretty appropriate analog.  Presumably they stream data into a buffer on the machine side and the display software has to process the data/dump it to the graphics controller (I'm thinking of something like a call to glutswapbuffers).


texts: Is ESD protection necessary on a battery powered device?

texts:
I'm currently working on a PCB design that will be battery powered. However, it will be necessary at times to plug the device into a computer to program it.

When the PCB is plugged into the computer, it will tie the PCB power common to the PC's USB power common.

Now my question: What kind of ESD protection is typically required/recommended when designing battery powered electronics? Because the device won't typically be grounded, it seems like I won't need to worry about possible static discharge when touching the device. However, I'm concerned about when I have it plugged into the computer...

Is it generally a good idea to always include ESD protection diodes, even when if the device will typically be battery powered?

Thanks!


texts: Underlying reasoning behind lead and lag nomenclature of compensation

texts:
If \$0<z, \;p\$, the Laplace transform transfer function \$\frac{s+z}{s+p}\$ constitute two distinct types of compensators.
If we look at this schematic, \$0<z<p\$ (lead compensation) implies that for \$s=\omega j\$ with \$0<\omega\$, \$s+z\$ clearly lies to the left of \$s+p\$ so that \$0<\arg(\frac{s+z}{s+p})=\tan^{−1}(\frac{p−z}{\omega^2+p^2})<\frac{\pi}{2}\$.
Similarly, \$0<z<p\$ (lag compensation) implies that for \$s=\omega j\$ with \$0<\omega\$, \$s+z\$ is to the right of \$s+p\$ so that \$-\frac{\pi}{2}<\arg(\frac{s+z}{s+p})=\tan^{−1}(\frac{p−z}{\omega^2+p^2})<0\$.

Is the following understanding about the phase with regards to the lead and lag compensation accurate? The relative location of the complex numbers \$s+z\$ and \$s+p\$ is the underlying reason that the lead compensation adds (and a lag subtracts) phase to the transfer function it multiplies.


texts: Interpretation of radiation resistance in receiving mode

texts:
Assume we have an antenna in receiving mode, connected to a matched load. The equivalent circuit is a voltage source in series with the antenna feedpoint impedance and the load impedance.
As we know, the feedpoint impedance is made up of a reactive component, an ohmic resistance and a radiation resistance. Now, since the load is matched, half of the intercepted power will be delivered to the load, while the other half will be delivered to the ohmic and radiation resistances respectively. The power delivered to the ohmic resistance will be converted into heat, but how to interpret the power delivered to the radiation resistance? Is this part of the total power reflected by the antenna?


texts: Can I increase resistance to cut down on LED power consumption?

texts:
I am totally new to electronics, and it's just a small hobby. I have 10 LED's that I want to connect in series. I am hooking it up to 4x 1.5V batteries (it's what I had around), so I assume that becomes 6V.

Before I get to the LED's, I have a single 220 ohm resistor.

From what I understand, these 10 LED's should use up more than 6V, and not be able to glow.

Is it because of the resistor that they work? If I increase the resistor value, will it glow less, but last longer?

The only reason I put this resistor on, was to make sure nothing blew.


texts: Need advice on converting NO switch to NC on alarm clock

texts:
I'm trying to modify a Lego alarm clock for my kid.  It has a select switch to turn the alarm on/off.  It also has a NO push button (smack his head) which lights up the display for a short time and also activates "snooze".

My goal is to make the push button briefly open and close the "alarm on" circuit, which will reset it for another 24hrs.  Similar to cycling the alarm on/of switch (not fun).  I expect this will negate the snooze function (that's good).  I would like it to keep the LED light function (I think it will still work).

Basically I need a relay, but I am limited on space.  I think a transistor or something similar should work for this, but I would like help on what is available and how to use it.

I attached a crude schematic to help explain.  I am able to tap into either side of the push button, but can only reasonably tap into the load side of the alarm switch.  It is part of a "switch only" circuit board feeding many switches ("set time", "hours", "min", etc..) with 3V+ common and the return wires to the clock IC/display board are where I can splice in.