texts:
I'm new to Oscilloscopes and so this question may be a simple one. We have a Rigol DS1104Z Oscilloscope and would like to compare the same point in the circuit at different times as the voltage changes based on the type of input. We would like to save these traces, open them as separate channels, so we can line them up and visually compare them.

We have tried saving off the waveforms as "wave" or "trace" output types but cannot figure out how to load both of these onto the oscilloscope at the same time to compare them. Perhaps this is not possible on this oscilloscope. But say you wanted to characterize the voltage changes for a particular pin on a touch screen microcontroller based on various user input. Theoretically, how would you compare two different "inputs" side by side for that same pin? Is that something you could accomplish on the oscilloscope?

Thanks


texts:
I have a motorcycle battery rated as 8.4 Ah (20 HR). It also says 8 Ah (10 HR) and I am not sure what the difference is.

Anyway, I have a GPS tracker fitted with a rated consumption of 5 mA. According to this formula I have to divide battery capacity by consumption:

8.4 Ah from battery / 0.005 A consumption = 1680 hours (70 days)

Is this correct? The reason why I am posting this is because the battery says 8.4 Ah, which is only double as many mobile phone batteries:

Why is this motorbike battery so heavy then if it's only double the capacity? Is it because it's a 12 V one? My knowledge in electronics is zero as you can see.


texts:
I'm reading a paper, and the first sentence is: Most dynamic systems are controlled by discrete time controllers
What is a discrete time controller ?
Thanks


texts: Echo in voice to the caller while receiver with headphone hving wire replace

texts: Hi I just replaced the old wire in my headphone with new one.But while using headphone the caller hears the voices with his own echo but while me having headphone on has no issue of echo can speaks with clear voice with no issues.


texts: DC-DC isolation for my car stereo... Where do I start?

texts:
I recently noticed that my jeep's stereo whines with a frequency that seems proportional to the rpm of my engine (and alternator), and is louder when my headlights are on.

If my stereo was powered by AC electricity it would be no problem to add an isolation transformer, but since I am working with DC I really don't know how to isolate the stero from the rest of my vehicle's power system.

A quick eBay search came up with some small ICs that appear to be DC isolators but none of them exceed 1W - an I have a 200w stereo.

How should I go about isolating my stereo from the rest of my Jeep's electronics?

Alternatively, What if I were to add a huge cap in parallel with my car battery, would that help keep things smooth?  If I used five of these 3V capacitors in series I would essentially have a 4F, 15v capacitor.  Would that be able to prevent noise from my alternator and headlights from affecting my stereo?


texts: Room lines stills on my pcb and the top layers tracks are not displayed in 3D view, Altium

texts:
The fact is that I have routed. I would like to know how to proceed when this kind of thing happens when using altium.

The routed tracks can be seen perfectly in 2D view. But when click 3D view I can only see the buttom tracks.

I don't now if a strange lines are involved on this. The lines appears in 2D only if a zoom enought. But it can be seen without zoom it on 3D view.

I was trying to delete them, to select them and get information or even to look for belonging layer. But it seems not to be in any active one. They also can not be moved, neither being selected.

I put an image to show what I mean. This lines seems to look like an old lines when the room of components was created during the first schem importation. I think they are some kind of garbage from components room.

How can I tourn off them? or how can the routed tracks of my top layer can be shown in 3D view? bottom tracks are visible in 3D view.


texts:
I want to shield a capacitive touch sensor circuit from external EMI/RF noise. It's for a commercial product meant to be used in every kind of reasonable environments. I don't have a specific bandwidth or noise source to protect form. It's more generally to improve the reliability.
I also need to keep costs low. Certified, big brand, solutions are too expensive.
My plan is to use food aluminium foil isolated by adhesive plastic film layers on both sides to avoid contact with the solder dots on the PCB. The foil is connected to the circuit ground of the PCB with a multi stranded wire. (Don't care about the colour of the wire, normally it should be black). The wire is glued on the aluminium foil with an adhesive copper tape. The glue of the copper tape is conductive. The impedance between the foil and GND is as low as my multimeter can measure.
Some people say that aluminium foils oxydate very quickly and because of that, the contact can be bad. But I don't think that's an issue because the glued copper tape isolates from the air and, IMO, should prevent oxydation between the two materials.
Moreover, I think that food foil is not oxydable but I'm not sure of this.
I have an even cheaper solution with aluminium on paper used in floor heating systems. It looks like the aluminium layer is very thin, fragile and more oxydable, not shiny as the food foil.
The advantage is that only one side needs to be covered with adhesive film. It reduces manufacturing time.
The foil would be applied on the internal side of the enclosure, and around the PCB. The enclosure could be any standard in-wall or on-wall plastic enclosure.
The shield and the circuit ground can't be connected to earth because it causes errors in the touch sensor system.
Question: How would you rate this solution? How effective, in term of percentage or dB of external interference? Or compared to other materials?
Other materials also embraced are quality copper foil and zinc plated steel sheet. But would add to cost significantly.
Sub-Question: Is the aluminium foil thickness important? Would the aluminium paper be less effective than the food foil because of this?


texts:
I'm taking a module on wireless design and we were told that the IEEE 802.11b standard has a band of 2.4 to 2.4835 GHz and that it is divided into 13 channels. Now, my question is, does that mean that it can only support 13 devices at once? I couldn't find any explanation of this online.

I know it's kind of a vague question.


texts: I have this transformer which is 240VAC to 11.4VAC. But when I hook up my multimeter I am only reading about 1.2V. I have my multimeter configured to read AC and the scale is also correct. However my multimeter isn't true RMS. Could this be causing a problem? If not what else could be the problem?


texts: Detect Battery Insertion in USB Charging Circuit

texts:
I'm using an MCP73831T as the charger IC, I've figured out how to detect the charging/charged, this was easy, however, I would like to know when the battery is actually plugged in, I know when the usb power is in via the PWR_SENSE, this works good, so I can deduce that if the usb is not plugged in and the MCU is running then obviously the battery is connected, the problem is detecting whether the battery is plugged in while the usb is also plugged in.

I've tried a couple sensing circuits, the "SECOND TRY" (see schematic below) might work, I can read an ADC value and if it is essentially higher or lower than ~N (where ~N is just about some number, e.g. 900ish), when the battery is charging the value will be < ~900 and when the battery is charged it will be > ~1000, though I feel like there is a better way this can be done.

This is all very new to me still so I'm at a wall at the moment on other options and search hasn't helped. I know that the battery voltage will be no more than 4.2v, which is why I was thinking somehow using a zener, e.g. the VUSB will be > 4.2V, the battery will be <= 4.2v, I feel like I can use this, but not sure how.

Anyhow, here is the schematic I have, the green lines is the normal charging circuit, which seems to all work well, the blue is one try with an ACS712 and the orange is another try.

Any ideas? am I on the right track?


texts: LC low pass filter: intuitive understanding

texts:
The figure below is an LC low pass filter and its bode plot.
As we can see the ratio Vout/Vin is larger than 1 around the resonant frequency.
Is there an intuitive explanation why the ratio is larger then 1 here?


texts: Can a purely reactive element exhibit resistive properties?

texts:
This question arises from a power factor correction example, consider the circuit below:

simulate this circuit – Schematic created using CircuitLab

For the specified frequency
$$Z_R=36\Omega$$
$$Z_L=48j\Omega$$
$$Z_C=-75j\Omega$$

Combining yields:
$$Z_{eq}=\frac{(Z_R+Z_L)*Z_C}{Z_R+Z_L＋Z_C}=100\Omega$$

Now I kind of understand why the reactive components disappeared, since the inductor and the capacitor worked to cancel each other out. I don't however understand where the extra 64ohms of resistance came from.

And since we are on the subject, I'd also like to know what happens to the voltage drop across the inductor and capacitor in the power factor corrected situation. Do the impedances disappear and therefore there wouldn't be a voltage drop?


texts: Tube power supply capacitors replacement

texts:
I'm building the following power supply (credits to Audio design guide):

I would like to replace C5, C8 and C9 with 1000uF capacitors (with the same voltage rate). From my understanding these capacitors are meant to limit the ripple and to provide a clean and stable voltage, so I think it should be ok to have more capacitance here. Am I right?


texts:
I am beginner in this field. I made a charger with 7805, 10 uF, 100 uF, 100 nF capacitors and 9 V non-chargeable + 3 V rechargeable batteries. The output current is 0.6 A (I used battery instead of solar panel in picture).

And the phone charges but it is hanging on previous percentage. What's the problem? Can non-chargeable battery charge rechargeable battery?


texts: MATLAB PID Tuner producing the wrong output?

texts:
I'm trying to apply a PID controller to my transfer function in MATLAB to get the step response, bode, pole-zero, etc. This is the code I'm using to create the Transfer Function and open the PID Tuner app:

s = tf('s');

R = 10;         % Load resistor
Rc = 130*10e-3; % Output cap ESR
C = 1410e-6;    % Output capacitance
Rl = 100e-3;    % Inductor resistance
L = 500e-6;     % Inductor value
Vi = 30;        % Input voltage

% Buck converter transfer function
G = Vi * ( (R + (s*R*Rc*C))/((s^2) * (L*C*(R+Rc)) + s*(R*Rc*C + Rl*C*(R+Rc) + L) + R + Rl) )

% PID Tuner
pidTuner(G, 'PID')

The response I get is this after some tunning (click to view it bigger):

The Kp value is really low compared to the Ki parameter which makes me thing there's something wrong? But the step response seems right so I go ahead. Now I use this program to simulate my PID controller and do some plots:

% PID Parameters from PID Tuner
Kp = 0.175
Ki = 371.22
Kd = 0

% PID Controller
H = pid(Kp,Ki,Kd)

% Close the loop
T_pid = feedback(G, H)

% Plot the step response
figure(1);
step(T_pid)
grid on
title('Respuesta transitoria en lazo cerrado (plano continuo)')
xlabel('Tiempo')
ylabel('Amplitud')

And this is the step response I'm getting:

Which is waaaaaaay different from what PID Tuner gave me before. According to the docs of the feedback() function I think I'm using it right:

But somewhere on the Internet I found it used like this:

T_pid = feedback(H*G, 1)

And this gives me the exact same step response as PID Tuner but I don't understand why! What's the proper way to use it?


texts: Application of offset voltage to non-inverting input of the op amp

texts:
When we analize the effects of the offset voltage at the outlet of an amplifier configuration, we consider that this voltage is applied to the non-inverting input. At least it appears so in all the books I have reviewed so far. Is there any particual reason for this?
Thanks for your help


texts: Increasing the delay using 'option' register in Pic16f877a

texts:
I have learned that the maximum 'delay' possible in pic16f877a running with a source of 11.0592MHz (11059200 / 4 actually) is 23 ms.. without using software delays (delay_ms( ))..

the calculation was max_delay = ((FF-00)xPrescalarxTimeperiod) = (255x256x3.62xe-7) = ~23ms..

My question is how to 'increase this delay to 1 second' without using software delay?


texts: Equivalent replacement for a centered 4pin potentiometer?

texts:
I need some help in understanding the pots pictured above.
How does this 4pin pot work? What is the function of the 4th pin?

Would this be the correct replacement if I want to replace the centered pot with plain resistors?


texts:
I have a a transformer for my speaker (230VAC -> 9VAC). The primary of the transformer is basically a coil.

Is it not dangerous to pull out the transformer from the outlet?

I know that in coils if you suddenly force open circuit high voltage can appears..


texts: How to connect a 2.4ghz 4ch RC receiver to a brushed dc motor controller?

texts:
I currently have a 36vbdc 800w motor connected to a 36v 800w motor speed controller (similar to what they use to control ebikes) just like this one: https://aws.robu.in/wp-content/uploads/2016/02/919811586_739.jpg (I don't know how to upload pics or wiring diagrams to my question or I would).

I would like to use a 2.4ghz 4ch RC remote transmitter and receiver to control the motor speed instead of the wired throttle I currently use, which is a 3pin hall sensor (+5v, Gnd, sensor) twist throttle.

Is there any way to connect the RC receiver to the motor controller to use the remote transmitter to control motor speed? How would I go about this?

I believe both the RC signal and the hall sensor are PWM, but do I need a receiver board to interface with the RC receiver and the motor controller?

Would I need to implement arduino into the equation?


texts:
The given image is from first edition of this book

To me the first sinusoid seems valid, in sense that values can be computed at different points.
However, in the case of second sinusoid I fail so see a logic for computing the various values given.
The question is
Is the second figure valid?
If yes, how ?
Update
It seems I have created much confusion/ambiguity, and I just realized that I didn't use the 'radian' in my calculation for the points of sinusoid( I'm so pathetically used to the 'degree' unit)
What I wished to say was that for the first sampled sinusoid i.e. cosine(pi*n/6) I can, very easily, compute it for n= 1,2,3... and its period, T = 12
For the second case, cosine(n/2), I couldn't compute its values at various 'n' (for the sake of it I didn't/couldn't put in there the 'radian').
Sorry fellows!


texts: What is the purpose of capacitors and resistors in this USB bus?

texts: Trying to understand the purpose of the capacitors and resistors in this bus powered configuration for the FTDI chip, I think the capacitors are for filtering high frequency noise, not sure what the resistors for though, maybe line termination ?


texts: Can the length of a wire impact SPI transmission?

texts:
I'm trying to wire a DotStar LED strip to another one. I have soldered on both ends of the added strip:

VCC to VCC
GND to GND
CO to CI
DO to DI

I'm using SPI to control the LEDs. For some reason, the added strip does not work. When I test for continuity from the end of the original strip to the beginning of the added strip, I have a closed circuit on VCC and GND, but not on CO to CI not on DO to DI.

I have soldered, resoldered, cut the strip shorter in case the copper paddings were damaged, but I still don't get any continuity.

Having assembled many of those strips together with success, I don't understand what's going on this time. The only difference I noted is that the wires I used to connect those strips are longer than I usually do (about 8 inches long).

So my question is: Can the length of the wires impact the good functioning of SPI?

Thank you in advance for your help and suggestions.

EDIT:
Here's the (unorthodox) wiring schematics, hope this clarifies the question.


texts: TEG in series require power balancer/align adapter?

texts: Do Thermoelectric Generators (TEG) in series require a power balancer, when storing the energy to a battery source? If not, what should I do for my design to distribute to a battery source more effectively.


texts: How to change reg in two different always blocks?

texts:
How can I change/alter a register's value in two different always blocks for synthesizeability?

For example:

reg temp;

always @(posedge clk1) begin
  if(...) temp = 0;
end

always @(posedge clk2) begin
  if(...) temp = 1;
end


texts: Rotating a motor according to calculated output

texts:
I have 13 photodiodes. Positive connection from battery is connected to the positive end of each photodiode. The position of photodiodes is as shown below:

 o  o  o
 o     o
 o  o  o
 o     o
 o  o  o

I would like to connect a motor to the output of these photodiodes.

Now when I throw infrared light on some photo diodes, they will give me 9V output as I have connected 9V battery, others will give 0 as output.

Suppose I throw light on it as below: (generated number 1)

 o  o  1
 o     1
 o  o  1
 o     1
 o  o  1

I want the motor to complete 15 iterations, stop there for 2 seconds and again complete 15 iterations in reverse direction

Suppose I throw light on it as below: (generated number 2)

 1  1  1
 o     1
 1  1  1
 1     o
 1  1  1

I want the motor to complete 30 iterations, stop there for 2 seconds and again complete 30 iterations in reverse direction

Suppose I throw light on it as below: (generated number 3)

 1  1  1
 o     1
 1  1  1
 o     1
 1  1  1

I want the motor to complete 45 iterations, stop there for 2 seconds and again complete 45 iterations in reverse direction

And similarly...

Can somebody just give me an idea of how can I accomplish the above mentioned task? and also what materials I would need?


texts: Generator speed, and power output. Frequency

texts: When you have a sudden change in load, I understand that you can expect to see sudden, voltage/current spikes. I also understand that you can expect to see a generator speed up or slow down for a short duration as this load change occurs. So I understand that as the generator changes rpm, the frequency output of the generator must change, even if it is for a short moment. During this short moment while frequency, and VI both increase is where I'm a bit curious. I've been trying to find some kind of formula that explains how frequency and power or current or voltage are related, I'm a second year electrical apprentice, so try and use terms I would understand! Thanks :)


texts: Large resistance of diodes measured by ohmmeters

texts:
Many multimeters have a diode mode and I have always used this mode to measure diodes. Today, I happened upon a Fluke article that explains you can use the ohmmeter mode to measure diodes as well:
http://en-us.fluke.com/training/training-library/test-tools/digital-multimeters/how-to-test-diodes-using-a-digital-multimeter.html

In particular, it states that the resistance of a diode (when measured in the forward-bias direction) is on the order of kiloohms and megaohms. I was initially skeptical so I powered up my benchtop Agilent multimeter, and sure enough, a 1N34A diode shows a resistance of 5kΩ.

My first thought was that the ohmmeter's voltage is too low to adequately "turn on" the diode. My diode has a 0.6 V turn-on voltage, which is typical. However, https://electronics.stackexchange.com/a/140531 says that ohmmeters have voltages of 1 or 2 V, which is more than enough for sufficient current to flow.

Could anyone help explain this? I would expect the incremental forward resistance to be on the order of 100 Ω.


texts:
Can an antenna signal (from an antenna cable) be transfered along with an ethernet signal through a category 5 cable? Will I lose too much signal quality?

Antenna specification:

Digital indoor antenna DVB-T
For terrestrial, digital signals (UHF/VHF/FM and DAB-receiving).
Frequency range:
    VHF: 174-230 MHz
    UHF: 470-862 MHz
Amplification:
    VHF/UHF: 28 dB
Powered by included AC adapter 230V or directly via DVB-T 5V/40 mA (set top box/digital TV).
RF cable:
    IEC to F connector, 1,5 m
Size:
    Width:  115 mm
    Depth:   35 mm
    Height: 180 mm

The antenna manufacturer is Biltema. I think the antenna model is being discontinued by the manufacturer. Biltema has released a newer model, almost (at least visually) identical to the one I have, but for some reason you can't find it in the online catalog.


texts: Switching Fuel Pump through MOSFETs instead of Relays

texts: I'm a member of a Formula Student Team of VIT University, India. We currently are building a power control board where our Engine Control Unit switches the relays which drive the Fuel Pump which consumes 20A approx and Fan which consumes 8A peak. Our Engine Control unit gives grounding signal to switch on the relays and I'm planning to replace the Relays with MOSFETs. I've bought IRF9540 MOSFETs and tried to switch the devices. Everything seems fine except for the MOSFET driving the Fuel pump, Which gets very hot even if a heatsink is installed. Is there any way to reduce the temperature of the MOSFET as there are temperature sensitive devices near the MOSFET.


texts: Recharging multiple batteries with solar panel

texts:
I have 1 solar panel: 7v, 1.5watt
and 1.2v Ni-Mh batteries, 3000maH
I am planning to use it to recharge my 1.2v batteries, I am not sure if i can charge 5 x 1.2v batteries using this solar panel. Should i be connecting them in series or in parallel or do i need some sort of voltage regulator?

Also is it possible to connect 6 x 1.2v batteries to this solar panel?


texts: Logic equation for truth table with don't care condition

texts:
Problem 1

How I can get the Boolean equation (in sum of products form) for this truth table with a don't care condition:

X Y Z
0 0 1
0 1 X
1 0 X
0 1 1

I should ignore the rows with don't care or there's something that I need to do?

Problem 2

And in this case:

X Y Z
0 0 0
0 X 1
X 0 1
0 1 X

How I can get the Boolean equation?


texts: Why this current regulator won't regulates?

texts:
I'm trying to make a current regulator to power up some LEDs. For now I'm working only on PSpice models.

The circuit above works well if the sensing opamp is configured as voltage follower or even if the voltage of the shunt resistor is directly reported to the inverting input of the main opamp U2A w/out the U2B.

Now, if the U2B is used to amplifying the shunt voltage resistor, in order to make this lower of at least 10 times to absorb 10 times less power, the opamp should amplifying 10 times this voltage and report it on the inverting input of U2A.

Under PSpice, by varying the Vcc from 4.5 (the minimum to have opamps working under this input values) to 12V, with this U2B which apmplifies fo 10 times, the current is like this. Where noramlly should remains stable under 50mA. The average value that you can see depends also on the base resistor of the BJT.

What am I missing?


texts: PN junction band gap - equal across all devices?

texts: With a given material eg silicon, is the band gap constant across devices? For example, at a constant temperature is the band gap of a diode ("diode drop") exactly the same as that of (say) an NPN transistor? If not, what kind of variation would one expect between devices?


texts: How to handle power failure in embedded SOC

texts:
I'm familiar with using BODs with microcontroller devices so that the system is safely pulled into reset and started when the supply is normal.
I'm also familiar with projects on SOCs on devices like Raspberry Pi, which can suffer badly when a power outage occurs.  I'm assuming what usually happens is file-system corruption?  Whatever the cause, it's not uncommon for a Raspberry Pi (BeagleBone, etc) which is suddenly powered off to fail to boot cleanly again when powered up.
But there are many commercial SOC devices in our homes (like routers etc) which run embedded linux and which don't ever seem to suffer from this.  I don't have to shut my router or my LTE gateway down before I power them off, but they always seem to boot cleanly.  What tricks are used to achieve this and can I incorporate them into my own projects?
Thanks!


texts:
I'm using AD7190 to sample 4ch differential voltage, but the AD7190 only has four input pins. To fix that, I use AD8422 to convert four differential signals to four single-ended signals. The schematic I'm using for one channel is down below.
My question is,
(1) I have four channel, can I use one AD8541 to set four REF pin voltage of four AD8422?
(2) How much current of these REF pin usually draws?
(3) I'm using ADR423 voltage reference for AD7190, can I use AD423 ref output and divide it to 0.6V and feed into AD8422 ref pin.
(4) Did I need to enable the buffer mode of the AD7190 input?
Thanks!


texts: How can I temporarily short-circuit two adjacent poles on a circuit board cheaply?

texts: On the image below I need to short circuit GP100 to enter flash mode on an esp-chip. I can't afford a soldering iron atm (and also don't know how to solder). I'm currently trying to do it by holding small screwdriver between the pins. I need to hold down a button and plugin a USB at the same time, so it's kind of tricky. Is there any other good trade-trick for doing this?


texts: How to modify an SD card so it will be read only?

texts: I checked SD card pins and their descriptions and saw that there is a "data input" and a "data out". If I covered, removed the data in pin, would it block all the writing requests to the card?


texts:
I am trying to replace a rocker switch in an aquarium hood. The original switch has a rating of 4A 125vac. I am having a hard time finding this exact switch. Is it acceptable to replace with a 6a 125vac?

update:
Thanks for the responses. There are two ballasts and two small cooling fans being operated by the switch.


texts:
I have a load I control via back to back SCR during zero crossing circuit. The load is powered via 208Vac and pulls about 15A. I have an EMI filter using safety caps at the output.

I need to detect if the load has a fault gone open. I can only detect if it is faulted open, if I try to apply voltage and the current is not there.

But how can I detect the load fail open during cycles where the load is off?


texts: How to measure microphone output impedance

texts: Is there a method to measure the output impedance of a condenser microphone?


texts: store word assembly instruction in risc-v

texts:
I'm really confused about the store instruction in risc-v. When I store word from register to memory, after the word is copied into the mem, does it sign-extended or zero-extended or perhaps something else occur? if it's extended, does the extension starts from the lower bits or the upper bits?

I tried to solve this exercise but i can't understand why the orange (0x3) is the right answer.

these are the steps I followed:

reg x11 gets the number 0x3f5 (0011 1111 0101 in binary) and is zero-extended to fill all the 32 bits
the number is copied from reg x11 into reg x5 and is zero extended again to fill 32 bits
i start counting bytes from the lsb so after 1 byte offset i'm pointing on 0xf and i load this byte

what is wrong with my solution?

thank you.


texts:
In a project I am using a 74LS05 to provide an ESP32 microcontroller with 6 open-collector outputs. Actually this is fine for 5 of the outputs, but for the remaining one I'd rather have a full push-pull driver, since the rise time I currently have is still too high (and I am already using a 470 ohm pull-up resistor).
I cannot use an ESP32 output directly since the output needs to be at +5V when high.
I'd like to keep the solution as simple as possible. I was thinking that maybe I could add an external BJT or MOSFET to "complement" the open-collector output but I have no idea of how to do that.
Any hints?
EDIT: Here's some additional info:

I don't want to add a 74xx04 for just one output, the other 5 outputs are fine open-collector-style.
I am using LS logic because the project is retrocomputing-related. I could switch to an HCT but would that change much?
I don't know the exact characteristics of the input I have to drive. it's the right mouse button input of the Amiga Paula custom chip, which is notoriously hard to drive.
I can take some measurements with a scope if that helps.
On a different project I am driving the same input straight from an output pin of an AVR microcontroller and in that case the signal rises "immediately".

EDIT2: Here's an old scope screenshot showing how slow the signal is rising (blue). It needs to be high before the following clock rising edge (yellow). I can't remember what pull-up value I was using when I took this screenshot though, maybe 1k or 820 ohm.


texts:
background:
My goal is to use an Arduino with two proximity probe (sensors) to achieve some output.
It is worth mentioning that the output of the proximity probe has two components:

DC output that determines the position or the GAP

AC component on the top of that DC voltage to determine the vibration

The proximity probe sensor has a negative voltage output from -5 to -12 volt DC and then the AC is on the top of the DC,
I have two parts in my circuit to achieve two outputs suitable for Arduino as they should be from 0-5 volt

the first one is to get the AC of the signal, as appears on the
upper part of the whole circuit, the filter is a second order
high-pass filter to separate the AC from the DC, which will give an
AC output oscillating around zero volt. This output needs to be
shifted up by 2.5 volts so that my signal will be centered around
2.5 volt not zero. the two resistors as a voltage divider will take care of that.
the second part is to get the raw signal , what I am doing basically
is that, I have a 15 volt adapter to shift the negative sensor
signal and then two resistors as a voltage divider, so that will
make the signal suitable for arduino example: if my signal is -7
volt DC and 1 volt AC , the shifting circuit will shift the signal
by 15 to be + 8 volt and then this 8 volt will go through a voltage
divider as appears on the lower part of the signal

The experiment and testing:
I tested the system on a more realistic environment ( which is pump driven by a motor in a plant )
to compare my DAQ with an industrial and already proven DAQ, I captured the same signal for both of them.
lets just look at the AC part
and here we can see the two signals
this is the signal captured by my DAQ

and here is the signal captured from the industrial DAQ

we can see that my signal is totally distorted!

I suspected 3 factors for this distortion

the Resolution of my ADC
aliasing
time synchronization

and this is how I approached each of these:
1. the resolution:
the resolution of my ADC is 9.5 bits in a reference voltage 5 volt
which will give us  5/(2^(9.5)) = 6.9 mv step which is good enough I guess
the resolution of that ADC is 12 bits, but I am not sure about the reference voltage
I ran another experiment in the office to see if my ADC can capture this small voltage which is in the range of 300 mv
and the results were fine

as we can see my DAQ can capture these small voltages
2. aliasing
my DAQ sampling frequency is 5000 Hz. Figure below shows the FFT of the signal from the test that was carried on in the realistic environment. As we can see, there is no frequency components above 1500 Hz.

The bandwidth of the signal is around 2500 Hz and my DAQ sampling frequency is 5000 Hz. Aliasing only happens if there is frequency above 2500 Hz. From the above figure, there are no frequency components above 2500 Hz and there is no way aliasing can occur.
3. Time synchronization
During the test, the data taken from the industrial DAQ and my DAQ were not synchronized.So the data is different to one another. It is hard to synchronize the two DAQs and signal may not be steady
the question is ! what other reasons may cause this distortion? and how to overcome it?
and comments and observations are higly appreciated


texts:
I am trying to make sense of this logic diagram for an ON Semiconductor 7-segment display driver. What is this logic symbol? I have never seen it before, and I have not seen it anywhere online after looking for about an hour.

Here it is in the larger logic diagram:


texts: Bandpass audio filter in combination with PGA2311 analog ouput pins

texts: I am working on modular preamp and I have Digital&Analog Power Supply, motherboard with CPU and Volume Control daugtherboard. On Volume Control Daughterboard there is an PGA2311 Volume Controller IC from Texas Instruments and my question is. Do I need analog audio bandpass filter on output side of this board and do I need buffer stage on input of this daughterboard?


texts: How to control microphone-speaker connection between two SIM800Ls with a GPIO terminal?

texts:
There is a device consisting of two SimCom SIM800L quad-band GSM/GPRS modules and controlled by an MCU, presumably ESP8266. The idea is to let the first SIM800L call one person, the second SIM800L call another one, and then these two guys can talk to each other.

Currently schematic is as follows, and it seems to work.

However I need to programmatically control whether microphone inputs are connected to speaker outputs or not. In other words, there needs to be a way for the MCU to decide when exactly parties start hearing each other and when they stop hearing each other. For this purpose I have a single free GPIO terminal.

The question is how use this GPIO to cut and later resume connection.


texts: 16V8 PLD alternatives for fast clock-to-data turnaround time

texts:
Context:  I'm prototyping an MIPI I3C Basic slave device implemented on a PSOC5LP.   (I3C is similar to I2C, but is spec'd to run at up to 12.9 MHz.)  Due to a speed limitation of the PSOC, I'm considering using external programmable logic (e.g. a 16V8) to implement one small part of the design.   I'm looking for a more modern alternative to the 16V8 series parts.
The programmable logic on the PSOC can handle most of the timing requirements, but there is one spec'd clock-to-data timing that's hard to hit on the PSOC.   The I3C spec calls this tSCO, see figure below.

For optimal operation, the I3C Basic spec says SCOmax is 12nS, but the best I'm likely to get out of the PSOC is > 23 ns.   Reading up on available parts, it seems that at least some variants of the basic 16V8 PLD can achieve clock-to-output time of 10ns.  That would do the trick, but it seems that in general 16V8s, and the like, are typically programmed out-of-circuit and require a CPLD programmer with specialized programming voltages and waveforms.
Question: Are there are alternative CPLD parts that can be programmed in-circuit, without programming voltages > 5V?
I'm thinking that a small FPGA might do, but it seems like overkill.
Note: the way SCOmax is defined, it doesn't include rise/fall times on the bus, but minimizing it gives the most headroom for the rise-time problems of bus capacitance.


texts: I have a 2 ton split AC that would draw about 12A current and is rated for 2260W input power at 230V. With this much information how do I choose a solid state relay? Since the rating is inductive what do I look for?


texts: Problems enabling remote voltage-sense Rigol load DL3021 via SCPI

texts:
I am automating some tests with Rigol hardware. There is only one bottleneck in the SCPI implementation that I can't figure out: How to enable the remote voltage-sense terminals on the Rigol DP3021 through SCPI commands.
It seems to be undocumented in the Rigol programming manual.
I found some undocumented commands in this EEVBlog topic: the relevant command appears to be :REMote:SENSe:STATe
If I manually enable and disable the sense terminals, I can query this register :REMote:SENSe:STATe? and see the boolean status change as expected: 0/1 = Disable/Enable.
However, if I write to this register :REMote:SENSe:STATe 1 the physical sense terminal does not change state unless I seize local-control and open the Utility menu. Only then does the device physically switch to the remote sense terminals - I can hear the relay click and the screen shows the status.
It's as if opening the Utility menu triggers some status update.
Can somebody with SCPI experience comment?
For now, my work-around will have to be to manually enable the sense terminal every time the device is powered-up. I'm honestly a little bummed out that this isn't documented in the programming manual as it seems to be such a fundamental function.


texts: When checking for continuity between two points on a PCB, how do I know it's not going through an inductor?

texts:
When trying to debug a non-working circuit on a PCB, it can be difficult to trace the circuit flow visually, as described in the answer to this excellent and related question:
How can I reverse engineer a simple through-hole board?
Traces on the top layer can be hidden under bulky components like transformers, heat sinks and capacitors, so sometimes you have to take an educated guess and use the continuity setting on a standard multimeter to check where a signal is going.
However, this will also "beep" when the signal goes through an inductor. Missing that could lead to a time-wasting misunderstanding of the circuit.
It might also beep when going through a low-value resistor, but I'm not so worried about those since it's easier to see traces around and under an axial resistor.
Question
Is there a simple way to check for continuity that does not signal positive for inductors of "reasonable" sizes?
Obviously every PCB trace has stray inductance but I don't want to limit any answer by setting an arbitrary cutoff.
Let's assume I have access to a basic multimeter, power supply, oscilloscope, and function generator.


texts: No datasheet for SunFounder ADXL345 - can I use a datasheet for the same part number from a different manufacturer?

texts:
I'm just getting started with electronics (with Arduino) and have bought this SunFounder accelerometer with part code ADXL345 from Amazon.

My problem is I can't find a datasheet anywhere from SunFounder for this part.  I found this datasheet on SparkFun's website for an ADXL345, which seemed like it matched the part as the first few lines of the datasheet description matched exactly the description for the part description on Amazon ("The ADXL345 is a small, thin, low power, 3-axis accelerometer with high resolution (13-bit) measurement at up to ±16 g. Digital output data is formatted as 16-bit twos complement... etc")

But then I noticed that the pin layout diagram in the SparkFun datasheet doesn't match my part:

So my questions are (sorry, I'm really really new to electronics):

What does the part code for an electronic component (like ADXL345) actually mean if different manufacturers can produce chips that look different / different pins etc. but have the same part number?
Is it safe to use the datasheet from SparkFun for ADXL345 for an ADXL345 made by SunFounder or will there be subtle differences in how they work?

Thanks!


texts:
I have an Arduino Duemilanove that I have used for various tasks (including signaling servos). When I got Sparkfun's Wifly shield I was unable to get it working. I then got an Arduino Uno which (surprise) did work with the shield. This leads me to believe that somehow I have damaged my original Arduino.  I suspect that it may have been due to controlling a servo.

I am aware of the Servo library and have successfully used it in the past. I am controlling a regular servo (steering servo) and a brushless motor (from a 35A ESC, which the servo plug is attached to) on this R/C car.

However I'm wondering if there is potential for damage to the hardware under certain situations. Of course I won't be powering any motors off of the Arduino itself, but do I have any guarantees that the signal pin of a servo won't draw too much power or do something else that may be a problem?

I could come up with a voltage follower circuit, which might be safer. I'd need to find some op-amps for that, though.


texts: What benefit is there in synchronizing my switching supply to the system clock

texts:
Working on a power supply design, some of these integrated buck/boost all-in-one dc/dc switching supplies have selectable switching frequency and some can synchronize to an external clock.

What benefit can be found from synchronizing my switching supply to my system clock (or fraction of)?. For references there is only one clocked ic in my device (a DDS chip) and the rest are either asynchronous logic or just basic analog components.

I'm specifically looking at the LTC3115(datasheet) as my master regulator, with daisy chained 79/78XX style linear regulators for the rails.


texts:
I have built an audio amplifier with a  Texas Instruments LM4766 chip amp. It works beautifully. I have performed some torture testing that involved driving a pair of large bass cabinets (rated at 300W), mostly to determine if my proposed heatsink is sufficient.

When I drove the amp as loud as it would go before audible clipping, I noted the maximum temperature of the heatsink tab after it plateaued (59C). Then I pushed it into audible clipping, and the temperature of the heatsink tab dropped to about 56C. In an attempt to keep it somewhat scientific, I used the same audio content for the range of testing.

The question then is this; when the output devices clip, are they entering saturation mode and turning fully on, thereby dissipating less heat?
Could it be so simple?


texts: Starting on electronics from zero - transistor timer

texts:
I'm just starting on electronics, trying to build a few circuits but can't understand properly how things work.

I got this circuit and put on a breadboard, but the power source I have is 5V instead of 9, so I had to recalculate the resistors to make it work, but it doesn't.

I just don't understand how this circuit works and the source website is quite bad on explaining why they are connecting the components in that way.

How and why this works?


texts: Why the encoder isn't giving a proper square wave?

texts:
I have two encoders. As it can be seen below, one of them gives a proper square wave but the other doesn't.

What could be the reason for such behaviour? Thanks!


texts: Placing a bypass capacitor on an LCD w/built-in serial controller a good idea?

texts:
I'm trying to learn more about bypass capacitors and am wondering whether an LCD that I have should have a bypass capacitor or not. I have an LCD that uses a built-in controller, a PIC16F690 for serial communication. I'm aware of the general rule of thumb that an integrated circuit requires at least one bypass capacitor. I'm not sure if my LCD that has a built-in controller falls under this category. I'm also not sure whether or not LCD's in general are considered integrated circuits. I'm able to operate the LCD just fine without any bypass capacitor. The data sheet for the LCD makes no mention of needing a bypass capacitor. Would it be a good idea to place a bypass capacitor anyway?

The data sheet for LCD in question: http://www.newhavendisplay.com/specs/NHD-0216K3Z-FL-GBW.pdf


texts: Necessary to put all power planes together for 4-layer pcb?

texts:
It is my first time working on a 4-layer pcb design with PCIe golden finger. I have 2 voltage levels, 3.3V and 12V. I set the third layer to be the power plane. Does it mean that I have to always put my two power planes on this layer?

In my case, for 12V, all the connections can be done on the top layer. I am not sure whether I can just create a power plane 12V on the top layer. And if it is wrong, how can I make the connection between the top layer 12V connection with the third layer 12V power plane? It might seem a bit weird as I already make the connection on the top layer.

Thank you!


texts: AND Gate and posedge CLK ? simple question

texts:
I'm trying to do the seq system as the picture, I'm sure it's simple but I don't remember the "gate" of this.

This clock cond will be used for sending bit in UART.

reg cond;
always @(posedge clk or negedge clk) begin
    if (enable == 1) begin
        if (clk == 1)
            cond = 1; // ############ ERROR this line
        else if (clk == 0)
            cond = 0;
    end
end

This code is working in simulation but I got an error when I'm trying to synthesize it: The logic for <cond> does not match a known FF or Latch template. The description style you are using to describe a register or latch is not supported in the current software release.

cond is only use for this just below the previous code:

always @(posedge cond or negedge enable) begin
***

I'm beginner at Verilog, please help me.

Thank you.

Edit:

I have every 100us data from an ADC. I want to convert to BCD and send in ASCII with UART/Serial communication.

The frequency of data and the frequency of the baudrate are different. I got some problems because for example for the second sending, it won't detect D but C, then it will send C and not D. Since it's my first verilog project/FPGA, I tried to do it as my brain is used to. Means with event, start, enable, finish signals etc... I think it's more how a uC/uP works than a FPGA. But I'm learning.

I am sure it's simple but I've been in for 2 weeks...


texts: Diode populated keyboard matrix: Wire two separate buttons to the same output?

texts:
I have an encoder board for a 16x8 row/column switch matrix.
An absolute beginner to electronics but using all of the great online resources for research the best I can. However, occasionally it turns out to be surprisingly difficult to find an answer to something very specific.

As a reference from the manufacturer distributed user manual, the traditional diode populated wiring diagram can be seen on page 4: User manual

I illustrated my question to sum up what I'm asking:


texts: Common emitter bjt amp Q point with and without current mirror

texts:
What is the real benefit of voltage divider CE BJT amplifier schematic like that? If I use different BJT's in real life with various betta I'll give different voltage drops XMM1. Different betta of real BJT's willn't allow to center the Q-point voltage XMM1 on output curve. Or it's not critical to allow Q-point some drift on output curve?

I'm also tryring to use current source instead R3 to fix Q1 collector current but I can't understand is that schematic usable in real life? And I can't understand how to select R3, R4 values if I know Q1 collector current (that equal to I_ref tuned by R1)?


texts:
Determine the poles of the following circuit given that W/L is 50/0.5, Id = 1mA, Rs= 1k, Rd = 2k. Assume no channel-length modulation effects.

I decided to find the poles by inspection and examining the output node, I see that the ouput pole should be at
$$w_{p1} = \frac{1}{R_DC_D}$$
Simarily, the input pole,
$$w_{p2} = \frac{1}{R_SC_S}$$

I have no idea how to calculate Cs or Cd. The question specifically asked me to determine the poles. Is there any way to calculate the capcacitances just by using Id and W/L as that's the only thing I haven't used yet.


texts: How to associate RX/TX of the BLE RN487x with a LED?

texts:
I assembled the scheme suggested by Microchip for the Bluetooth Low Energy BLE model RN4871, pointed out in the schematic of FIGURE 5-4 of the Datasheet (page 26). I've connected a led to Pin 12 (P0_2) and set the BLE as UART transparent, according to User Guide (page 59, topic 4.2 UART TRANSPARENT CONNECTION).

According to the manual, it's necessary to associate the I/O Port with a number that identifies the Service Handle. But, when BLE is as UART Transparent, I can't list the Services and their Handlers by de command "LS".

Question: How do I create a script to make the LED blink when I receive (or send, whatever) data via RX/TX?

USER GUIDE:
http://ww1.microchip.com/downloads/en/DeviceDoc/50002466B.pdf

DATASHEET:
http://ww1.microchip.com/downloads/en/DeviceDoc/50002489C.pdf

PICTAIL:
http://ww1.microchip.com/downloads/en/DeviceDoc/50002547A.pdf


texts: What is my battery max current allowed for charge?

texts: I have a 5000mAh battery and in the spec it says "1C" for max charging rate. Does it mean it will be 1A maximum, and so it will take 5 hours to fully charge the battery ?


texts:
Hi sorry for the poor schematic. I want to use a MOSFET H-Bridge to drive a linear actuator based on outputs from a microcontroller. The actuator I'm using has inbuilt limit switches so when it reaches its maximum point the switch will be toggled and there will be no current across the motor. For the program I'm writing to the microcontroller I need to know the full range of motion of the actuator, and so I was thinking of having the gate of an NPN BJT connected to the drain of M1 with its emitter going back to the microcontroller so that as long as there is current across the motor a signal will be sent back to the microcontroller, and when the limit switch is toggled the signal being sent back will stop and I will know the range of motion from that. Is this a viable option or does M1 need to be grounded for the circuit to operate as intended. If it is a viable option, how should I reduce the voltage and current so that the BJT I use can handle it?

simulate this circuit – Schematic created using CircuitLab


texts: How is noise reduced using a sigma-delta converter?

texts:
Perhaps I'm sleepy but I can't quite get my head around how a sigma delta converter takes the noise that is in a bandwidth of (X) Hz and by over sampling spread, that same amount of noise over 2(X)Hz.

My understanding is that basically we're doing two filtering stages.

First stage is taking the input and passing it through a relaxed analog filter ( something like a 2-pole butterworth??) with a low cut-off frequency and this allows us to use a uber-high sample rate.

Next we do some funky noise shaping to boost the high frequencies which are already outside the bandwidth we're interested in.
Then we pass that through a second digital filter that has a very sharp cut-off at our corner frequency.

Lastly we use a much lower sample rate (2-3 times the input frequency) when we rebuild the signal to save on the bit count.

Do I have that correct?

So why would the noise density that's present at 0-3 kHz using a Nyquist/Shannon sample rate, spread out over the whole spectrum and effectively become less if we are using a more relaxed filter and over-sampling?

Doesn't make sense to me.


texts: How to prevent tombstoning using via-in-pad with small SMD discretes

texts:
My current project is using via-in-pad technology for BGA chips. They are proper VIPs: filled with conductive material and planed flat. I would also like to use these VIPs for my discrete decoupling components.

For example, the following components are 0201's (0603 metric), the trace width is 5 mils (0.127 mm), and the green pads are ground. If you look closely, there are 12-mil (0.305 mm) VIPs embedded in the green pads. These VIPs are full-length plated-through-holes, but only connected to a ground plane on the next layer.

(My decoupling traces are actually very short; I'm showing this non-decoupling component to make the example simple)

These boards are double-sided, and so will go through two reflow cycles. They will use lead-free solder.

I am concerned that having a ground-plane connection opposite a surface trace will cause tombstoning during reflow.

Is this a valid concern?
If so, can I minimize the issue by providing thermal reliefs on the internal ground layer?
And, if #2 is true, is this a bad idea anyway?  I'd rather not add inductance to my decoupling circuitry...

How is this generally handled?


texts: How can I measure which finger is moving in a glove?

texts:
I am considering building a pair of gloves that make a chorded keyboard. In order to measure whether or not a finger should be triggered, I intend to leverage the fact that as you curl your fingers inside of a glove, the top stretches to accommodate the increased distance.

I'm kind of a electrical noob, but is there a sensor out there would fit this purpose? Or Is there already a known technique for measuring finger movement in gloves?


texts: Can a ferrite bead accidentally rectify RF?

texts: If the ferrite is designed to filter out in the lower region, up to 100 MHz, and the pass-band signal is even way lower, 60Hz, I'm thinking that the ferrite is constantly saturated along with the 60Hz signal. Now let's say 900MHz ISM-band signal is coupling into this, I wonder if the saturated ferrite would actually rectify some of this... what do you guys think?


texts: Generated current in a \$3\times450\$ VAC \$60\$ Hz \$1150\$ kVA generator

texts:
Let's say I've a \$3\times450\$ VAC \$60\$ Hz \$1150\$ kVA generator. How much current will there be generated when it runs at maximum capacity?

MY WORK:

The total Active power over a three-fase system is given by:

$$P=\sqrt{3}UI\cos\varphi\tag1$$

Where \$U\$ is the line voltage and \$I\$ is the line current.

The total Reactive power is given by:

$$Q=\sqrt{3}UI\sin\varphi\tag2$$

Where \$U\$ is the line voltage and \$I\$ is the line current.

The total Complex power is given by:

$$S=\sqrt{3}UI\tag3$$

Where \$U\$ is the line voltage and \$I\$ is the line current.

So, I know that:

$$1150\times1000=\sqrt{3}UI\tag3$$

  But what is the line voltage? Is it \$450\$ volts? So, then we get: \$1150\times1000=\sqrt{3}\times450I\$ which give that the line current equals \$I=\frac{1150\times1000}{\sqrt{3}\times450}\approx1475.5\$ A.


texts: Do unintended latches only happen for signals in the process sensitivity list?

texts: I read in one book that an unintended latch requires you to have a process section where there is a signal in the process sensitivity list but don't assign to in every path. But that doesn't make sense to me, because for example you don't assign a value usually to the clock or reset. Also I've read other examples that don't meet this criteria. What is required?


texts: PG2 GPIO output on Nucleo-F767ZI doesn't function

texts:
I have made a board on which I plug the Nucleo-F767ZI microcontroller board. There is one GPIO pin that I cannot get to function as a digital output: PG2.

This is my code in mbed-os:

static DigitalOut myPin_A(PG_2);
static DigitalOut myPin_B(PG_3);

...

static void someFunction()
{
    myPin_A.write(1);    // <- This one doesn't work :-(
    myPin_B.write(1);    // <- But this one works!
}

I thought: "Perhaps this problem has to do with mbed-os". So I have tried the ST HAL:

static void someFunction()
{
    GPIO_InitTypeDef GPIO_InitStruct;

    GPIO_InitStruct.Pin = GPIO_PIN_2;
    GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
    GPIO_InitStruct.Pull = GPIO_NOPULL;
    GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
    HAL_GPIO_Init(GPIOG, &GPIO_InitStruct);

    GPIO_InitStruct.Pin = GPIO_PIN_3;
    GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
    GPIO_InitStruct.Pull = GPIO_NOPULL;
    GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
    HAL_GPIO_Init(GPIOG, &GPIO_InitStruct);

    HAL_GPIO_WritePin(GPIOG, GPIO_PIN_2, GPIO_PIN_SET); // <- This one doesn't work :-(
    HAL_GPIO_WritePin(GPIOG, GPIO_PIN_3, GPIO_PIN_SET); // <- But this one works!
}

As you can see, I get exactly the same result. I've tried another Nucleo-F767ZI board standalone - I don't plug it into my custom board to reassure myself that the PG2 pin isn't affected by anything outside the Nucleo - but still got the same result.

EDIT
I have generated a new project from scratch with CubeMX. As you know, CubeMX does not support mbed-os, but freeRTOS instead. When using freeRTOS, the pin PG_2 works, using the code given above.
Why don't I get it working when mbed-os is running? This is so strange :-(


texts: How to get a default UCF file of Xilinx Virtex-5 XC5VLX110?

texts:
How to get a default UCF file of the Xilinx Virtex-5 XC5VLX110?

It doesn't seem to be anyhere. If I have to make it by myself, would you let me know how to generate a UCF file for a Xilinx Virtex-5 XC5VLX110?


texts: Vacuum tubes are much more idiotproof than transistors. Grid current does flow during a significant part of the drive cycle in some classes of amplifier operation. Many high power tubes have really low grid current ratings. Why are the ratings so low? Are other things like electromigration limiting factors before thermal issues? What actually happens when you exceed the manufacturers grid current rating?


texts:
I'm currently learning for an upcoming exam about diodes. I have the following exercise about LED, but I'm really having a hard time to figure it out (Sadly, the teacher isnt willing to help us).
I have an AC source with Us= 230 V at 50Hz
The LED is Uf= 1,7V and Iled= 20mA
The Diode is a BAY61.
I need to determine the resistor R1.

I don't really know where to start. The teacher never explained how to use datasheet so i googled BAY61 and found a datasheet, but what information do i need?

Can anyone please help me?


texts:
This diagram is of the little device to read the data from P1 port on the DSMR electric meter. In my case it is Landis E360.

RTS and 5V pins are shorted in the diagram and that is to trigger the data being constantly sent out of the port.
Now I would like instead to trigger data being sent occasionally by pulling RTS high to 5V. I want to do it programmatically using one of the NodeMCUs/ESP8266 out pins.

How do I modify the the schematic to achieve this?


texts: Altium hides the whole board and other connections when I'm routing

texts:
I was working with Altium when suddenly it began to behave in this way

I do not know but I guess that some shortcuts were pressed to pass in this visualization mode.
Can anyone help me?


texts: I am making a custom footprint for a component. However if I use the component then Eagle doesn't auto route any connections to that component. Does anyone have any ideas?


texts:
For some projects with the Raspberry PI 2, for which I require 5V+12+24V, I baught the Mean Well RT-125D

I put the switch in order to have "230V" displayed, as in my Country, the voltage is 230V.

I put the brown wire on the "L", the blue on the N and the green-yellow to the ground:
.

I put the plug, and I checked with the multimeter, I have 230V. I checked the voltage between the Pole "+5V" and the pole "COM". But it varies(seems to go from 0V to 5V each second). Additionally the green led on the right of the pole is blinking(at the same frequency than the 0 to 5V). I hear also a small noise, at the same frequency also.

Is there something that I'm missing? Or is this power supply defect?


texts:
I'm trying to write a VHDL moving average (evenly weighted) module that uses FSMD(ata). From what I understand, the states needed would be something like fetch, divide, output. Below is the process I wrote, but I feel like my logic is a bit off. Note that the data I'm averaging is just a constant array of 8 bit numbers, so I figured it should be fine to use a non-causal design.

The data has 64 entries, and at the moment the window for the average is 4.

process (clk,rst) is

    variable temp : integer range 0 to 1020;
    begin
        if rst = '1' then
            count  <= 0;
            n_state <= s0;
        elsif (clk'event and clk = '1') then
            c_state <= n_state;
            case c_state is
                when s0 =>
                    for i in 0 to (len) loop
                        temp := temp + pattern(count+i);
                    end loop;
                    n_state <= s1;
                when s1 =>
                    temp := temp/4;
                    n_state <= s2;
                when s2 =>
                    data <= std_logic_vector(to_unsigned(pattern(count),8));
                    data_avg <= std_logic_vector(to_unsigned(temp,8));
                    n_state <= s0;
                    count <= count+1;
                end case;
        end if;
    end process;

How wrong does this look?


texts: Arduino + Escudo + EL Wire on analog port: need pull-up-down resistor?

texts:
I am using a pair of El Escudo boards on my arduino. I've stacked them and fed the digital I/O pins to the first one and manually wired the analog pins to the second one. All works fine - sort of.

I wanted more than eight wire segments, so I thought I could just set the analog pins to 255 or zero and turn those wire segments on and off. I've discovered that I can sometimes turn it on, but can't really turn it back off. Sometimes it doesn't turn back on, but only if it has already been on.

I suspect that because EL wire is mostly a capacitive load that I may need a bleeder resistor to ensure the port fully changes state.

Should I put a 10K resistor to ground from the analog port? One to vcc+? Both?


texts: Currently, I'm using standard headers with a pitch of 2.54mm (0.1"). These are quite big on my boards. Are there any surface mount standard headers, say in 0.05"?


texts: How to calculate the Temperature rise of PCB and its surrounding air from the power PCB consumes?

texts:
I am having a difficulty understanding some mechanism regarding heat generation from an electronic PCB (Printed Circuit Board) and its effect on atmospheric temperature.

I don't know if this question is related to This forum or its related to Physics, but I am going to post it here as my concern is regarding Electronic PCB.

Please bear with me on this long question.

Problem:

A PCB with specifications:

Surface mount-multi layered with few through-hole components
(capacitor, LCD etc).
The circuit designed on it consists of Capacitors, Resistors, EEPROM,
3.3 V regulators, RC Power Supply circuit, LCD, MCU etc.
Area = 66 cm^2 Power Dissipation in the circuit on PCB = 0.44 W to 1.0 W, typically 0.5 W
No heat sink, or specific heat generating components.
The circuit is operated on 3.3Vdc
Enclosed in a Box of volume 1007.8 cm^3.
The box has holes (where wires are passed to PCB) that can
accommodate air flow easily.

I want to find:

The temperature rise of PCB when it consumes 0.5 W power.
The temperature rise of air inside the box because of heat transfer
from PCB and time.
Time to reach equilibrium when PCB surface and air inside the box
are at the same temperature.

Note: I don't want to go into details or very deep into the design (as I have seen some designer do the very complex and detailed calculation for these purposes). I only need to find the general idea about the heat transfer of this topology. For that, if it's easy, you can assume that PCB is just a heat generating surface (amount of heat can be calculated from power).

Now, I came this far,(this work was done by someone else on this forum)

The copper side with the traces is modeled as a sheet of copper
rather than traces.
The body is thin enough that thermal conductivity within the body is
unimportant, and the entire device is considered to be at a uniform temperature.
Only the two broad surfaces contribute to the heat loss, the sides
are neglected.
The surroundings, including the air and radiative syncs, are at a
uniform temperature Ts
Thermal coefficients: ϵcu=0.78, ϵpcb=0.50, hup=7.25 W/m2K, hdown=3.63
W/m2K Under these assumptions, we can estimate the temperature of the
board by simply equating heat flows.

The heat coming in per unit time is from Joule heating from the current running through the copper and is given by qin=I2R = Power Dissipated

The heat flowing out has two escape mechanisms; radiative heat transfer to the surroundings which is given by

qrad=ϵσA(T^4 − T^4 * s) Here, ϵ = ϵcu +ϵpcb

and convective heat transfer to the air which is given by

qconv=hA(T−Ts) Here, h = hup + hdown

Now we just equate the heat flows

Qin=Qout

I2R=A[σ(T^4−T^4 *s)(ϵcu+ϵpcb)+(T−Ts)(hup+hdown)]

we can rearrange this to look like a quartic equation

σ(ϵcu+ϵpcb)T^4 +(hu+hd)T−[I2RA+σ(ϵcu+ϵpcb)T^4 *s+(hu+hd)Ts]=0

From here, I calculated the temperature of the PCB surface to be 28.9 degrees Celcius, assuming the temperature of the air inside the box to be 25 degree Celsius.

Questions:

Have I done it correctly? if not please tell me the reason (cause I
am not confident about this).
If its ok, how do I find the temperature rise of inside the box and
the time it will take to raise that temperature?
Will air inside the box and PCB surface ever be at equilibrium and
at what temperature and what time will it take to reach that state?

I know this is a mess, but I can't find any help regarding this specific problem, I tried other methods and tricks but the results are far too much wrong that even I know they are not right (one such example; temperature cam out to be 300-degree Celsius).

Guys, you don't have to solve this problem for me necessarily, but please give me the directions to how to approach this (as I am fresh electric engineer and don't know about heating, thermodynamics of this level).

Any help about this will be highly appreciated.

Thanks


texts: Cortex-M DWT cycle counter inconsistent measurement

texts:
I recently discovered that it's possible to use a free running counter embedded in most Cortex-M4 cores to measure the performance of a chunk of code.
I'm trying it on my LPC4370, where I want to measure how much time does it take to move a pin un and down.
My code is this:

/*SET UP GPIO debug*/
/* use with LPC_GPIO_PORT->B[DEBUGPIN_PORT][DEBUG_PIN0] = TRUE; */
Chip_GPIO_SetPinDIROutput(LPC_GPIO_PORT, DEBUGPIN_PORT, DEBUG_PIN0);
Chip_GPIO_SetPinDIROutput(LPC_GPIO_PORT, DEBUGPIN_PORT, DEBUG_PIN1);
Chip_GPIO_SetPinDIROutput(LPC_GPIO_PORT, DEBUGPIN_PORT, DEBUG_PIN2);
Chip_GPIO_SetPinDIROutput(LPC_GPIO_PORT, DEBUGPIN_PORT, DEBUG_PIN3);
Chip_GPIO_SetPinDIROutput(LPC_GPIO_PORT, DEBUGPIN_PORT, DEBUG_PIN4);

/*DEBUG Timer Init*/

uint32_t delta;
uint32_t max = 0;
uint32_t min = 0xFFFFFFFF;

LPC4370_InitCycleCounter(); /*Init DWT HW*/

while(1)
{
    LPC4370_ResetCycleCounter(); /* reset cycle counter */

    LPC4370_EnableCycleCounter(); /* start counting */
    LPC_GPIO_PORT->B[DEBUGPIN_PORT][DEBUG_PIN1] = TRUE;
    LPC_GPIO_PORT->B[DEBUGPIN_PORT][DEBUG_PIN1] = FALSE;

    delta = LPC4370_GetCycleCounter();

    if(delta < min)
    {
        min = delta;
    }

    if (max < delta)
    {
        max = delta;
    }
}

And the needed defines for the timer:

/* DWT (Data Watchpoint and Trace) registers, only exists on ARM Cortex with a DWT unit */

#define LPC4370_DWT_CONTROL   (*((volatile uint32_t*)0xE0001000))
/*!< DWT Control register */
#define LPC4370_DWT_CYCCNTENA_BIT (1UL<<0)
/*!< CYCCNTENA bit in DWT_CONTROL register */
#define LPC4370_DWT_CYCCNT        (*((volatile uint32_t*)0xE0001004))
/*!< DWT Cycle Counter register */
#define LPC4370_DEMCR             (*((volatile uint32_t*)0xE000EDFC))
/*!< DEMCR: Debug Exception and Monitor Control Register */
#define LPC4370_TRCENA_BIT              (1UL<<24)
/*!< Trace enable bit in DEMCR register */

#define LPC4370_InitCycleCounter() \
LPC4370_DEMCR |= LPC4370_TRCENA_BIT
 /*!< TRCENA: Enable trace and debug block DEMCR (Debug Exception and Monitor Control Register */

#define LPC4370_ResetCycleCounter() \
LPC4370_DWT_CYCCNT = 0
/*!< Reset cycle counter */

#define LPC4370_EnableCycleCounter() \
LPC4370_DWT_CONTROL |= LPC4370_DWT_CYCCNTENA_BIT
/*!< Enable cycle counter */

#define LPC4370_DisableCycleCounter() \
LPC4370_DWT_CONTROL &= ~LPC4370_DWT_CYCCNTENA_BIT
/*!< Disable cycle counter */

#define LPC4370_GetCycleCounter() \
LPC4370_DWT_CYCCNT
/*!< Read cycle counter register */

To compute the elepased time I do cycles_number*(1/f_clk): in this case f_clk = 204 MHz.

After a few try what I got is this:

min = 22 cycles (~100ns)
max = 2450 cycles (~12us)

Where this high value of max happens at the first iteration.
Here's a picture of what I see on the scope (which I believe agrees with the min measurement):

Putting the scope in single mode (DC coupling) I'm able to capture the first pulse:

From this I notice 2 things:

pulse length is 6us instead of the expected 12us (as measured with DWT)
smaller pulses do not have the time to range from 0 to 3V while this one does.

So, any idea why do I get this outlier?


texts: Testing an Analog Front End prior to installing a Sensor

texts:
I've designed a circuit around the TI LMP91000, a configurable Analog Front End (amperometric potentiostat, for use with electro-chemical gas sensors). In addition the circuit includes a 2.5V reference (for VREF on the LMP91000), and an 18-bit ADC.

Once the sensor is installed in circuit, it's very difficult to remove it without doing harm. I've experienced a significant number of failures late in the testing process (e.g. during calibration), that I don't understand the root cause of yet, but which I suspect are related to undetected manufacturing defects in the underlying circuit (i.e. not a problem with the sensors themselves). The upstream testing that I do right now is limited to just establishing I2C communication with the LMP91000 and the ADC before installing the sensor. If I could identify problems earlier, I could potentially fix them before installing sensors.

Is there a way to temporarily attach an external circuit in place of the electro-chemical sensor (i.e. using pogo pins connected to the working, counter, and reference electrode inputs) to inspire the LMP91000 to output an expected voltage so that I can demonstrate the analog front end is working correctly before installing a sensor? What would the composition of such a circuit need to be?


texts:
So i know this question is being asked almost everyday on thousands of forums, but i am still going to ask that same question but with a different intent.

Question #1:
As an example lets use linux bootable stick. you stick it in and you can use the whole operating system without even installing it. What i would like to do is have my code on SD card and plug it in a device of my own (arduino board) and have this arduino execute code (without copying it in to the flash) with ability to select which part of the code it executes. so it is like bunch of independent programs on SD card.

Question #2:
And again linux example, basically it copies the OS in to RAM and executes it from RAM, since there is no external ram on any of the arduino boards how can it be attached, maybe using some DRAM controller could help ? for example attaching 2 GB of ram.i know it is overkill or an 8 bit controller, but what if i would like to add more ram to lets say cortex M33 which is 32 bit controller and i am doing some video processing and i need space to store video, results of processing, and store a program that does processing.


texts: Why is a DC base voltage needed to attain faithful amplification?

texts:
I was studying about transistor biasing from an article, http://1drv.ms/1yU8B7C, and I have a question regarding this part:

Why should an extra voltage \$V_{BB}\$ be needed when there is already an voltage \$V_{CC}\$ available to produce \$I_c\$ current?


texts: Daisy chain multiple PCB with an existing IDC cable

texts:
I'm not sure, if I just miss the obvious, but I'm stuck on seemingly simple problem and can't find a solution.
I have a series of PCBs, I want to daisy chain. The number is between 8 and 12(max).
The distance between each about 500mm (just in case that matters).
I have an existing IDC cable with 4 free wires.
Each PCB has 8 devices, which I would like to switch on and off, from a microcontroller located on the first PCB.
So I need 8 digital outputs on each PCB.
If possible I would like to find a solution with the following criteria:

I would NOT like to have an address, that needs to be set on each PCB. So something like an I2C IO-Expander such as the PCA9557 is somewhat ruled out (or is there a smart way to set the address?).
I would NOT like to add an extra cable or one with more pins
As I will replace the existing PCB's, I am free to design whatever circuit onto the PCB's.

So with what bus or circuit can I do this / How I can daisy chain these PCB, with the given criteria?


texts: Does the stability of an LTI system depend on the input?

texts:
Consider a system \$G(s) = \frac{1}{s}\$. It is marginally stable, as it has its only pole at \$s=0\$.  However, if we apply a step input, the output is  \$ tu(t) \$, which turns out to be unstable. But, the stability or instability of a system should not depend on the nature of the input. If it has a single pole at \$ s= 0\$, it should remain marginally stable, no matter what the input is.

So, how do we reconcile these conflicting notions?


texts: Sound distorted from amp configuration, and one transistor variety getting too hot

texts:
The sound is distorted from my configuration. The transistor I'm using is an MPF4393. I need to add resistors and capacitors and how do I get more power (to make it louder) What should I add? Also when I use a 2N4401 instead, it gets too hot.

The configuration is: positive input at the base, emitter grounded, collector to positive speaker terminal, negative terminal hooked up to a variable voltage source (1.3v - 15v) & negative input source to the collector

simulate this circuit – Schematic created using CircuitLab


texts: In the intrinsic semi-conductors,the electrons are bonded by covalent bonds to the nearby electron,when we do doping the electrons make bond with the atom we doped,so the covalent bonds between the semi-conductor electron is broken?How are they still connected to each other?


texts:
SOLVED: I changed the infrared receiver and all went correctly, I am using the TSOP4838.

EDIT:I have modified the code, I have been testing the program more deeply and I have found something weird. I am using an infrared code receptor like this:

When the PORTB is linked to GND the microcontroller starts sending every second the message "while", but when I link it to the VOUT the microcontroller stops sending it( when shouldn't stop) and blink the led when i push some button on the infrared remote control. I really have no idea about what is happening here, i hope someone can help me with this.

I am making a program to read a code from some remote infrared transmiter. I have tested it in Proteus and it seems work, but it doesn't physically. Using my microcontroller (PIC18F2520) seems to don't enter to the interruption.

I show you the code below:

#include <xc.h>

#define _XTAL_FREQ 4433619

char infrared_code[6];
unsigned char UART1Config = 0, baud;
char MensajeTx[] = "Probando ";
int counter = 0;

void main(void) {

//Infrared entry.
TRISBbits.RB0 = 1;

TRISBbits.RB1 = 1;
TRISBbits.RB2 = 1;
TRISBbits.RB3 = 1;
TRISBbits.RB4 = 1;
TRISBbits.RB5 = 1;
TRISBbits.RB6 = 1;
TRISBbits.RB7 = 1;

//State LED
TRISCbits.RC2 = 0;

UART1Config = USART_TX_INT_OFF & USART_RX_INT_OFF & USART_ASYNCH_MODE &              USART_EIGHT_BIT & USART_BRGH_HIGH;
baud = 28;
OpenUSART(UART1Config,baud);

ADCON1 |= 0b1111;
EnablePullups();

RCIF = 0; //reset RX pin flag
RCIE = 1; //Enable RX interrupt
IPEN = 0;

INTCONbits.RBIE = 1; //Enable Interrupt per change on PORTB
INTCONbits.PEIE = 1; // Enable Peripherial Interrupt
INTCONbits.GIE = 1; // Enable Global Interrupt

INTEDG0 = 1;

ei();       //remember the master switch for interrupt?

while(1){
    for(int i=0; i<10; i++)
        __delay_ms(100);

    putsUSART("While: /n");
}
}

void interrupt low_priority myIsr(void){

//If is interrupted by change on portB
if (INTCONbits.RBIF){

    __delay_ms(14);
    __delay_us(224);

    for(int i=0;i<6;i++)
    {
        if(PORTBbits.RB0)
        {
            infrared_code[i] = 1;
        }
        else{
            infrared_code[i] = 0;
        }
        __delay_ms(1);
        __delay_us(778);
    }

    while(BusyUSART());
    putsUSART("Interrupcion: ");

    //for(int i=0;i<6;i++)
    //{
        //WriteUSART(infrared_code[i]);
     //   putsUSART(infrared_code[i]);
   // }
    putsUSART(infrared_code);
    putsUSART("/n");

    if(counter == 0)
    {
        PORTCbits.RC2 = 1;
        counter = 1;
    }
    else if(counter == 1)
    {
        PORTCbits.RC2 = 0;
        counter = 0;
    }
    INTCONbits.GIE = 1;
    INTCONbits.RBIF = 0;

    if (PORTB) {
        asm("nop");
    }

    for(int i=0;i<20;i++)
       __delay_ms(100);

}

}

I'm really working on it, but I don't find the cause, I would appreciate if you could help me with it.

By the way, when I have tested it on Proteus, don't know why, but to be able to read some change in PORTB0 I have to connect them all (from PORTB0 to PORTB7) even when I have just specified PORTB0 as digital input.

Greetings!.


texts: What type of oscilloscope can be used to troubleshoot 100BASE-T1 automotive ethernet?

texts: I would like to implement the 100Mbps single pair automotive ethernet specified in 802.3bw, otherwise known as 100BASE-T1.  I was told that in order to troubleshoot and test on this standard, the scope must be capable of 1 Ghz.  Is this accurate?  Why would this be necessary as opposed to an oscilloscope that is well above 100MHz such as one that is 200MHz, but still 1 GSa/s ?


texts: Problems reading correct data from AD7746 using STM32 I2C HAL library

texts:
I am trying to read capacitance and temperature from the AD7746 capacitance-to-digital converter, using STM32F103 and HAL I2C library (SDA and SCL pulled up with 2k and Vcc = 3.3 V). I did it before using AVR (using Codevision) and it worked fine, but now it doesn't work properly:
// ad7746 init
    HAL_I2C_Master_Transmit(&hi2c2, 144, (uint8_t*)Reset_address, 1, 100);
    HAL_Delay(1);
    HAL_I2C_Master_Transmit(&hi2c2, 144, (uint8_t*)EXC_SETUP, 2, 100);
    HAL_Delay(1);
    HAL_I2C_Master_Transmit(&hi2c2, 144, (uint8_t*)CAP_SETUP, 2, 100);
    HAL_Delay(1);
    HAL_I2C_Master_Transmit(&hi2c2, 144, (uint8_t*)CAP_DAC_A, 2, 100);
    HAL_Delay(1);
    HAL_I2C_Master_Transmit(&hi2c2, 144, (uint8_t*)CAP_DAC_B, 2, 100);
    HAL_Delay(1);
    HAL_I2C_Master_Transmit(&hi2c2, 144, (uint8_t*)CONFIGURATION, 2, 100);

and in a while() loop, I try to read data:
while (1)
  {
HAL_I2C_Mem_Read(&hi2c2,144, 4, 145, (uint8_t *)&VT1,1, 100);
HAL_Delay(1);
HAL_I2C_Mem_Read(&hi2c2,144, 5, 145, (uint8_t *)&VT2,1, 100);
HAL_Delay(1);
HAL_I2C_Mem_Read(&hi2c2,144, 6, 145, (uint8_t *)&VT3,1, 100);
HAL_Delay(1);
HAL_I2C_Mem_Read(&hi2c2,144, 1, 145, (uint8_t *)&CA1,1, 100);
HAL_Delay(1);
HAL_I2C_Mem_Read(&hi2c2,144, 2, 145, (uint8_t *)&CA2,1, 100);
HAL_Delay(1);
HAL_I2C_Mem_Read(&hi2c2,144, 3, 145, (uint8_t *)&CA3,1, 100);}

but in STMStudio I read all data 129 or 130 and they change together with the same, when I touch input of AD7746.
update:
Thanks for your advice. This is part of the AD7746 datasheet that explains write and read:

So for reading one byte of capacitance or temperature data you must first send start bit, write 0x90, and then write the address again, send start bit, write 0x91 and then read data but I get 6 similar data.


texts: Activating SSR for an AC motor via PWM input

texts:
I'm currently switching a single phase AC fan motor with an SSR.
Here is the following SSR:
http://www.crydom.com/en/products/catalog/s_1.pdf
I activate this relay by applying continuous analog 10V to its inputs.

What if I use a PWM signal instead which has 490Hz frequency, like for example default Arduino PWM output?
Since Arduino board doesn't have DAC, it mimics analog voltages by using PWM technique.

*For some reason I don't want to use digital outputs.

*I don't want the relay to switch on and off all the time which would cause too much heating.

My questions are:

1-) Is there a frequency limit for PWM where the relay would be always on? Or relay would always react the on of cycles of PWM what ever the freq of PWM is?

2-) I could use digital output for continuous analog voltage, but if I have to use PWM output at very low duty cycles
would I have problem with the relay?

Would the motor jerk if I were to use  PWM as analog DC input with this relay?


texts: Differential (RS-422) vs current mode signaling in noisy environments

texts:
I’m building some automation equipment for my shop that will be used in extreme noise environments (plasma cutting and TIG welding nearby, for example) and I’m trying to come up with the best signaling for connecting modules that is still reasonably cost-effective. The modules will live in a couple of rack cabinets, and have dual-shielded 8P8C modular cabling connecting units within each rack and between cabinets to carry both moderate-frequency (200kHz-4MHz) and near-DC signals.
My initial direction was to use AM26C31/32 RS-422 ICs on these links, for cheap and easy differential communications.
The ICs are rated for +/-7V common mode, and the power supplies are isolated. Therefore, the racks require some mechanism to limit ground potential differences. The RS-422/485 standard recommends terminating the cable shields at both ends through a few hundred ohms to tie the systems together, but if the building ground is continuous there is now a room-sized loop and it's connected to ground through a low impedance. Some of that might be mitigated by inductors on the shield-ground tie but I’m not sure to what extent, and high-frequency high-energy noise could radiate through the stub.
Second, in the case that the line is undriven, such as when a cable is unplugged, the received voltage has an indeterminate state. Therefore, they need fail-safe biasing, which potentially connects uneven power supplies.

I am now considering using a single-ended driver for one wire of each twisted pair, the other wire being a dedicated return tied to ground at the driver but not receiver. Receiving would be done by optocoupler, resulting in full isolation. This has the advantage of ignoring the GPD, removing the need to tie the cabinets strongly to ground and so while the ground loop through the building still exists, it should be better isolated from the ground plane. The other advantage is that logic zero in this system is <5mA or so, and the undriven state of the line is 0mA for a decent noise margin without biasing. Sadly, high-speed optos are expensive.

It’s still technically differential, but the swing is half that of the RS-422 drivers and I’m not sure how much unbalanced drive will affect noise emission at the wavefront vs the opposing magnetic fields of balanced drive. Four pairs share each cable so that noise would be of concern. CAN uses unbalanced drive in voltage mode and is generally considered pretty robust, but it’s not clear how much of that is its fault-tolerant protocol and lower data rates at short range vs RS-485.
I will have to use at least one of each, since off-the-shelf stepper drives use optoisolator inputs, and there is a required RS-485 bus to serve, but RS-485 transceivers are available with features to mitigate the need for biasing networks (though not GPD). So, given the possibility of a 200A welding arc going off a few feet away, what is the most noise-immune thing I can do? Can I solve the problems with RS-422 without going to expensive fully isolated receivers? Can anyone shoot some new holes in my non-EMC-engineer-approved plan? Am I overthinking it and both systems are good enough?
Thanks for any input anyone can provide.


texts: Whats the difference in a TVS of common anode vs common cathode?

texts:
I found this two TVS diode and there is a difference in the diagram of the diode representation.

Common Cathode:
https://www.mouser.com/datasheet/2/389/dm00207446-1798715.pdf
Common Anode:
https://www.mouser.com/datasheet/2/427/vcan16a2-03g-1713959.pdf
Is there any difference between this two? Or one of them is wrong?


texts:
The text says:
"A resistor is the simplest I-to-V converter. However, it has the disadvantage of presenting a nonzero impedance to the source of input current; this can be fatal if the device providing the input current has very little compliance ."

Does the above phrase means that the device which has very little compliance has low output resistance which means that if it is cascaded to an output circuit which contain a resistor as a simplest I-V converter ...the resistor will going to load the device due to its little compliance..since resistor is showing a little resistance enough to load the circuit...

second ..
As the inverting input is maintained at virtual ground..then how can a current can flow in the photo diode branch..how does the circuit the acts as a I-V convertor..

please help...


texts: LM359 Quartz Crystal Oscillator Schematic not working

texts:
I'm trying to design a Crystal Oscillator based on the LM359 chip and the schematic on the datasheet but it's not working. It does not do anything.
What I'm doing wrong? I changed some components because I don't have the ones on the datasheet.
By the way, this is not the first time I'm trying to design something that's on a datasheet and doesn't work...
Thanks in advance!


texts: Will get shock from Isolated transformer?

texts:
I have read a good discussion about the safety of an isolated transformer.

However, in my understanding, the secondary side of the isolated transformer is floating, so will it has a high potential difference with the Earth ground? If it does, because I am at Earth potential, will I get shock when I touch the secondary side?


texts:
im having some trouble finding an example of the time-instability that motivates the flip-flop. wherever i look, the explanations are awfully airy-fairy (or at least my understanding is). for example, here they explain that there can be instability if the clock pulse is sampling from combinational circuits. im looking for a concrete example of such instability (i need these things explained to me like im a six-year-old kid), not just saying "things can be unstable". if i wrote in a maths exam "the given implication can be problematic" without providing a counter example i wouldnt get half a mark, and by the same token if i were authoring an article that discusses motivating flip-flops i would see it essential to "prove" their necessity.

my problem is that if i have worked out that if the [maximum] propogation delay for a given circuit, i dont need to wait for a clock pulse edge, i can just sample the output after that amount of time. meaning, even with a flip-flop i have to work out my clock-pulse speed, so why go to all the trouble of having 2 latches when i know that the desired ouput will exist after 1 pulse-length of time?

so if i had many different circuits that relied on each others output, instead of flip-flopping them all, i would just activate them in the relevant order according to a clock-pulse. im obviously missing something simple here because as far as i can see the flip-flop functioning to save from instability isnt necessary...

the JK flip-flop is a nice way to "regulate" the ouput because it solves an altogether different problem, that when j=k=1 the toggle that the JK latch would otherwise perform for the entire cycle that the clock-pulse is 1, happens only once, which means the final output is deterministic - as opposed to undefined. although that doesnt explain why its necessary on a D latch and an RS latch.

on that note, ill add a second question. whats the use of the JK latch/flip-flop? it seems to be introduced in many texts as an improvement on the RS latch, because of the problematic s=r=1 situation and resulting race condition. however if we setup the RS in a flip flop, we provide ourselves with a better alternative to the JK flip-flop: this acts like an RS latch but when r=s=1 on the clock's rising edge both Q and Q' are 0, and on the falling edge theres no change in the slave latch. so the problematic situation of r=s=1 becomes stable. the only advantage JK has over this setup is that r=s=1 actually provides a new functionality of toggle, im not sure if thats a desired thing or not...

hoping for some insight...


texts: How can I describe mathematically what is happening in my home made LVDT variant?

texts:
I've built an LVDT (Linear Variable Differential Transformer) that is a little different than how it is conventionally done with 2 secondary coils positioned adjacent to a primary coil. My design is a primary and secondary coil directly on top of each other and a iron bar that will slide in between them.

There are a lot of resources about transformers that talk about a ratio of number of windings, but this is not the case here since the number of windings is constant, but the voltage changes.

I have a basic understanding of how it works, but I think it is incomplete and I need to relate it to equations.

When I insert the iron core, the inductance of both coils increases.
The first coil that is energized with an AC current, produces changing magnetic flux.
The second coil more strongly experiences the magnetic flux because of the iron core. At the same time, the second coil will produce a higher voltage because the iron core has increased its inductance.

The relevant laws to this, that I have found, are:

Faraday's Law (Change in magnetic environment produces emf)
Bio Savart's Law (Inductance and magnetic field)

Any help would be appreciated!

I've taken some data to relate displacement of the coil to voltage change in the secondary coil. It is mostly a linear relationship, excluding the last couple points.


texts: Particle Argon controlling 12V, using 3.7V LiPo

texts:
I am trying to control a 12V DC motor using a Particle Argon, powered by a 3.7V LiPo. To get 12V I am using this step up regulator, and to control the motor I am using this DC motor controller. I am also using the Particle Argon as my microcontroller with a typical 3.7V LiPo battery

I am able to control the motor at a lower voltage by dropping the duty cycle at the PWM pin, but when running (particular when changing direction or starting the motor), the Particle Argon resets.

I am assuming that the current surge required when powering the motor is causing the voltage at the microcontroller to momentary drop, thus resetting it. Any thoughts? Is there a better approach to accomplish this? Maybe a capacitor anywhere is the circuit to solve this problem?

Any insight would be GREATLY appreciated.


texts: digispark pin mode input_pullup reading low on pin 1

texts:
I have a Digispark dev board that I am using with the Arduino IDE.

I have set Pin 1 HIGH with pinmode(1, INPUT_PULLUP) and the LED attached turns on but when I perform a digitalRead(1), I get a LOW response.

Is it because the LED in turning on is pulling the pin low?? And if so would de-soldering the SMD LED be a solution to making this pin available?

Actually I have performed the same thing on pins 0,2,3 (ie. with pullups) and all pins read as high except pin 1.


texts: Help with wiring OEM LED turn signals that has 2 voltage inputs

texts:
The term AFS is used in the 2nd diagram to help differentiate between the
  bulb type turn signals vs the led type.

I'm trying to swap my headlights(without-AFS) to a higher trim version(AFS) on my 2018 Mazda CX-9 Touring. So far installing the higher trim headlight has been plug and play and everything works except the turn signal does not activate at all. I've never looked at an electrical diagram before and having trouble understanding what I'm looking at.

In the first diagram below, my vehicle's original headlight has "BULB TYPE" turn signals which is easy enough to understand: there is a "hot" wire and a ground wire.

However, the higher trim headlights utilize "LED TYPE" turn signals and I don't understand why it has two "hot" wires.

My vehicle is missing the B+ wire from the engine fuse box which I believe is a constant 12v even with engine off. I tried adding a connection from the fuse box that has a constant 12v to where the missing wire should go but this did not work. I'm also curious what does the dashed line mean in the 2nd diagram that connects the GY/L(F) to the GY(F) wire. Thanks in advance.


texts: Why are flat copper cables with holes used for high voltage ground?

texts: I saw that a flat copper cable was used for the ground connection in a high voltage lab. I was wondering whats the difference as opposed to a normal cable ?


texts: Analog to Digital Schemes - using different implementations?

texts:
We all know the standard(at least traditional) ADC with output being the binary representation in base 2. However, there are a variety of other encoding schemes that are much better and less prone to errors.

For example, the Gray code is designed in such a way that each successive number differs from the previous by only a single bit. Such a encoding scheme means that if the signal to be encoded signal went from 7 to 8, the representation would differ only by a single bit in contrast to the traditional binary where 7 -> 8 has a 4bit change.

In traditional binary:

 7       8
0111 -> 1000

In Gray code:

 7       8
0100 -> 1100

How would you implement such an encoding scheme? Do microcontrollers have the ability to use different techniques or are they tied to the traditional method unless a specifialized units are purchased?


texts: Is it bad to let an oscilloscope trace go off screen?

texts:
Lets suppose we are talking about a reasonable modern scope such as a Rigol DS1054Z.

I want too look at the ripple at the top of a 5v square wave. I'll change the volts/division and offset so that the top of the square wave is centered on screen. In this scenario the bottom of the wave form is way off screen.

Is this bad practice? What does the analog front end do when the waveform is off screen?


texts:
I'm using Microchip TC1071 in a circuit to provide an adjustable output voltage (appears to be pin compatible with LT1761-SD). My plan is to use a digital potentiometer (Microchip MCP4251) to control the output voltage within over some range. The schematics and layout are on solder pad here. The adjustable regulator circuits are in the upper left quadrant of both the schematics and layout.

I've got it all hooked up per their typical application circuit and it doesn't seem to work the way I'd expected it to. I have an 0805 100nF ceramic capacitor near the input voltage (pin 1) of the regulator. I put this 10uF electrolytic capacitor near the output voltage (pin 5). The high side of the voltage divider is connected to my digital potentiometer. The low side is connected to a 56 kOhm 0805 resistor. The \$\mathrm{\overline{SHDN}}\$ (pin 3) measures 5V as does the input voltage.

So I blew the digital potentiometer off the board and hooked up a fixed 47kOhm resistor. If I read the datasheet correctly, the voltage I should get out of the regulator in this configuration is {1.2 * [( 47 / 56 ) + 1]} = 2.21V. Instead, I measure about 1.6V. I'm staring at this datasheet and am somewhat baffled. Are my capacitors inappropriate to support this regulator (seems like there are some ESR requirements, but I can't tell what the ESR of my caps is)? They suggest using somewhat larger resistors for the voltage divider:

  The ohmic values of these
  resistors should be between 470K and 3M to minimize
  bleeder current.

But could this actually impact the accuracy of the output voltage (that much)? Does anyone have any experience with these adjustable regulators that can offer me some practical advice on getting the thing to work, and what I might be doing wrong?

Edit

I should note that I only need to source 50mA max, though 100mA would give some more breathing room.

Edit

Once I resolved the netlist error with some trace cuts and softwires, I was able to control the voltage as I had intended per the design.


texts:
I designed a wearable with a 3.7V Li-Po battery (381018). Everything worked good at the begining and now after 6 months I realize some circuits are not charging anymore. For what I understood when I was doing a small research about this problem, I found out the overdischarge protection of the battery is 2.V6 and the battery management controller (MCP73831) has a UVLO of 3.45V.

1.-Is this the reason why they don't charge anymore?

2.-I talked with the manufacturer and they told me the highest overdischarge protection for that size of battery is 3.0V. However, i can't find a controller with lower UVLO. Any suggestions?

Note: I can't increase the size of the battery because the moulds are already made.


texts: Is there a usb controller IC which give MCU USB capability?

texts:
It is disappointed that the MCU I want to use in my project does not have USB controller nor USB PHY capability. Can I simply add one standalone USB controller IC? I see device like FT2322h can translate USB to serial or parallel FIFO, is this the common way to do this job? Because it seems that I cannot achieve the full 480Mbps USB HS even using the parallel mode. Is there another better way?
Thank you!


texts: Active/"RedMere" HDMI Cables Explanation?

texts: How exactly do Active HDMI cables work? The only info I can find is that it somehow analyzes the edge of the waveform, but no information beyond that. RedMere used to have explanations on their website, apparently, but as their website is defunct, all technical documentation is gone.


texts: Using field emission to discharge low voltage static

texts:
I am looking for information on the efficacy of using field emission techniques to discharge low voltage static in microbalances. One method used in the past was to use a Polonium source to produce ionized air. I was wondering if anyone knows, or has heard of, using something like (say) carbon nanotube field emitters (very pointy needles) to do similar.

The discharge would be driven by the low voltage static buildup (tens of volts)


texts: FCC Re-certification if the brand name and outer casing changed?

texts:
I'm considering importing Wifi enabled electronics that are FCC and CE certified by the manufacturer in China. We will sell them in US/Europe under our company name (no mention of OEM). Does the FCC and CE certification for that electronic item needs to be under our brand name ?

Edit/Update: The device is a mini PC. We're making NO changes to electronics. The only changes are: 1. The Electronics will be placed inside a different Custom shell that better suits our purpose. 2. The Brand name and model name for this product will be different than what was used in FCC certification. The device is powered by a DC adapter, so the AC to DC conversion happens at the adapter level.

Update 2: The old case is an ABS plastic case and came with a sticker like wifi antenna that was positioned towards the front. In the new case the same antenna will be positioned more or less in same direction.