texts: How to calculate the currents of \$I_R\$,\$I_L\$ and \$I_C\$?

texts:
How are you? I am working in the next circuit, so \$I_R\$,\$I_L\$ and \$I_C\$
can be calculated.

The next data is supplied

\$R=?\$
\$L=4.3mH\$
\$C=220 μF\$
\$i(t)=15u_1(t)A\$
\$M_p\leq16.3\%\$
\$t_s\pm2\%\$ \$=10ms\$

The first thing done is calculate the model of the system, and I just used the inductor current, but it can be in terms the current in the resistance or the capacitor too, the coefficients must be the same:
$$\frac{d^2I_L}{dt^2}+\frac{1}{RC}\frac{dI_L}{dt}+\frac{1}{CL}I_L=\frac{1}{CL}i(t)$$
The next pass is about taking the parameters like the natural frecuency, damping ratio, gain; for this system:

$$\alpha=\epsilon\omega_n$$
$$2\alpha=\frac{1}{RC}$$
$$\alpha=\frac{1}{2RC}..[1]$$
$$\omega_n^2=\frac{1}{LC}$$
$$\omega_n=\frac{1}{\sqrt(LC)}..[2]$$
comparing 1 and [2]
$$\epsilon=\frac{\sqrt(L)}{2R\sqrt(C)}..[3]$$
Next try to calculate \$\epsilon\$, R and the  \$\epsilon@16.3\%\$
 - From the overdamping case
$$\epsilon>1$$ then $$\frac{\sqrt(L)}{2R\sqrt(C)}>1$$ or $$\frac{\sqrt(L)}{2\sqrt(C)}>R$$
then \$t_s@2\%\$ \$=\frac{4}{\epsilon\omega_n}\$ (I dont remember is this numerator is 3 or 4), so $$\epsilon=\frac{4}{(10\times10^-3)(\frac{1}{\sqrt(LC)})}=0.389$$. On tho R, comparing terms
$$0.389\frac{1}{\sqrt((4.3\times10^-3)(220\times10^-6))}$$$$=\frac{1}{2RC}$$
 From here, R is
$$\frac{1}{2(220\times10^-6)(400)}=568$$
$$\epsilon$$ of the 16.3%, ergh, say, the overpass at 16.3% is calculated from the definition $$M_p=e^{(\frac{-\epsilon\pi}{\sqrt(1-\epsilon^2)})}$$
$$Ln0.163=\frac{-\epsilon\pi}{\sqrt(1-\epsilon^2)}$$
and $$\epsilon_{16.3\%}=0.50$$

and using KCL
$$I(t)=I_{R_1}+I_{L_1}+I_{C_1}$$
But isnt clear how the parameters calculated are related to the currents.
Thanks in advance


texts: How to power multiple LED chips using single driver and several DC-DC CC converters

texts:
I have 5 pieces of 100W LED chips but customs won't let me import 5 pieces of drivers to power them unless I pay a ridiculous sum. They are 100 Watt LED chips rated 30-35V @ 3A.

I cannot find 36V LED drivers locally, So I need to choose a 400 to 600W LED driver and use several DC-CC converters.

There are 12 to 48 Volt drivers available; which voltage would be a better choice? Should I go for a lower voltage driver (12V or 24V) and step-up converters or higher voltage driver (36V or 48V) and step down converters to obtain a more reliable and efficient system?

My gut tells me to go with a 36V-600W driver and add 5 pieces of DC buck converters but I am not sure if it would be a long term & reliable solution. Can I succesfully power these LEDs using this DC converter?


texts:
I finished designing the given circuit using Matlab but I am getting some weird output results on oscilloscope.

and here is what I did

I used the commands to define the R, F , C, and everything else, then I used Simulink to design and simulate. should not the output be some sinusoidal waveform ?
could you please help me out on this?
it is asking for the gain? how do I find the gain from this oscilloscope output ?


texts: Questions from a current regulating and measuring circuit

texts:
In my previous question I asked about a simple topology suggestions for regulation of highish currents(around 10A) especially for resistive heating elements in 1...10 Ohm range. I concluded to use a MOSFET controlled via a PWM signal from microcontroller since PWM duty cycle is linear with the power of the heating element(I guess same linearity for the temperature).

And now after I made some readings about the importance of the current being measured, I would like to measure the current through the heating element and send this information back to the microcontroller. So I decided to measure the voltage across it and then divide this to the resistor value(neglecting heatin element's tolerance) and have an estimation for the current so forth and so on.

Before soldering this on a perfboard I wanted to have your opinions for the below circuit I modified so far:

And before going in detail here is LTspice simulation plots for the current through heating element, MOSFET's instantaneous power and average power and the final voltage output to the MCU input:

(left-click to see it better)

I want to go from left to the right:

The control signal is a 0...5V 490Hz PWM signal from a microcontroller pin.

A 12V 10A SMPS power supply will be used for a max 0...8A PWM current through the element. C4 and C1 are for noise in the supply.

Q1 Q2 are inverting logic. This is because I want MOSFET to saturate when control signal is ON. I could also use a logic MOSFET but I don't know if IRL3903 is a logic MOSFET from the datasheet. I don't know which parameter makes a MOSFET a logic MOSFET. Is that something to do with gate to source voltage being less than 5V? I have no idea so I decided to use this NPN inverter driver to make it usable for any power MOSFET.

In some examples I saw there is a 20k resistor between the gate of the MOSFET and the ground. In simulation I didn't find it necessary but I'm not sure if needed.

And for the measuring part I decided to use an an LM358 in a difference amplifier configuration(I'm not sure in practice it is a good op amp for this application). The voltage across the heating element is too high for the microcontroller and it is not pulled down to the ground because of the voltage drop across the MOSFET. If I shunt it between the source and the ground then I get less current. So I needed a negative gain meaning that 12V to less than 5V. So I obtain a gain of R4/R1=R3/R2=0.33. The reason I didn't use an inverting op amp configuration is I use a single power supply and inverting op amps have low input impedance. And I also didn't use a non-inverting op amp because as I mentioned then I have to shunt the heating element between the source and the ground.

One of my question is the gain I'm aiming is R4/R1=R3/R2=0.33. But the resistors should be matched. What does that mean? Would 1% tolerance resistors be enough for roughly measurements here(since I'm not measuring mV level small voltages)?

And finally I added a 4.7V zener for precaution to the MCU input. (Would it be good to add a 100Ohm 100n lowpass filter right before this?)

I would be glad to have your opinions or any major mistakes with this circuit.

EDIT:

I was suggested not to use a difference amplifier and a single ended op amp config instead together with a mOhm level low resistor. I tried to use a non-inverting config. since I have a single supply.

But I'm getting distorted output if I use a non-inverting configuration.
Here is the modified circuit with LM358:

And the plots for input(non-inverting input/blue plot) and the output of the op amp:

And here is similar issue with another opamp LMC6482:

Basically the gain must be (1 + R3/R7).

But the PWM signal is distorted(like a lowpass filtered pulse) and it doesn't go to ground when the input is zero.

How can I fix this problem?


texts: Simulating TPS54719 DC2DC in TI WEBENCH Power Designer

texts:
I'm interested in using TI TPS54719 to create 3 output voltages: 1.2V, 1.49V, 3.3V using three TPS54719 devices.
the same Vin voltage will be connected to the three devices and the Vin range is: Min = 3.3V, Typical= 5V, Max = 5.5V.
To create 3.3V voltage, I used the same elements I used for creating the 1.49V output circuit (which has good simuilations) and I have done this by changing the output resistors to Rfbt=45.3 kOhm, Rfbb=10 kOhm.
My problem is with generating 3.3V. instead, I'm getting 2V in simulation, although I'm using the required voltage divider.
Note: I can see in the summary of parameters that Vout Actual is 3.32 as intended.

The design:

The simulation results:

I want to understand how do I can know the Actual range of Vout by not just relying on choosing R1,R2 as in the following formula in Datasheet:

for example, by choosing the before-mentioned R2,R1 values I can theoretically get 3.3V in the output but in simulation it reached only 2V.


texts:
I'm trying to find $$\frac{V2}{V1}$$ as a function of x.

I found this circuit but noone gave good explanation. I think I understand the way this potentiometer works, but I just can't work out the equations to get result.
Also I tried to simulate this circuit and here is result (for simulation I assumed x=1) :


texts:
In the Wikipedia page and in every book they prove the transformation by equaling the equivalent resistance between any pair of terminals while disconnecting the other node.
https://en.wikipedia.org/wiki/Y-%CE%94_transform

Why this should make the two circuits equal? How can we apply superposition here?
I have searched everywhere for this answer. Nowhere has anyone explained this. Please explain the principle or this way of proof.


texts: Three-prong / USB power outlets in wooden desk

texts:
I am trying to mount a strip of three-prong outlets and a strip of USB charging outlets on an old wooden desk. I can handle the carpentry aspect, but I am struggling with the electrical aspect.

I need the basics: are there preferred types of three-prong / USB outlets for this, what type of wire should I use, safety, etc.

Thanks in advance.


texts: I wonder what these fibre-optic cables are used for

texts:
One cord. Two identical ends. Looks like female end would be similar to a phone style connection but it is not for phone.

Black cord, two ends identical


texts:
Hi i wanted to make a little hand heater for walking in the cold. The plan is to make a little clay square and put some wire in it, fire the clay and that should give me a good temperature conductor.

I know i should use nichrome for this but ive noticed that copper wire actually heats up very fast too using a 18650 battery( i used 20 gauge bare copper wire and a 3000mah 3.7v fully charged 18650, as soon as i touched the terminals, 5 inches of copper wire got burning hot).

My question is why not use copper wire? It gets hot and hardly has any resistance, but i would put a resistor in there too just to not overheat the battery, i would also use the hand heater in bursts( not continuously), so is copper wire a bad idea for a hand heater? Why?


texts: Low voltage (self-oscillating) boost for solar powered pond pump

texts:
Long story shortened:

I am currently designing a small filter for my pond using a small pump
(6V-12V, upto 540mA) with UV-C LEDs parallel to it. Currently, it is battery powered (9V, 6x1.5V AA cells) but I'd like for it to be solar-powered. These
individual solar cells, however, operate around 0.65V(4W, 6A), which
is why I would need a boost converter to step up the voltage. To
ensure the operating voltage of the cells is more or less fixed, I
would attach a battery to either the input or output voltage of the
converter.

Summary of the system:
Input:

Input voltage 0.6V/1.2V (two solar cells in series or parallel), I could cut them to obtain even higher voltages but I'd rather not as they are quite brittle. Sidenote: If I put 2 in series, I would get the 1.2V voltage needed for the YX8018 but the current would still be to high for that IC.
Input current, up to 6A according to solar irradiance

Output:

Voltage 9V (Led (Datasheet) forward voltage is ranging from 5-9V), so I took the maximum as batteries tend to drop below 1.5V as well

Here is a diagram of what I have in mind to clear things up. For now, I think that I should either put 1.2V batteries in parallel at the input or 6 1.5V batteries at the output but I am not sure what is best practice

I want to design or use a self-oscillating circuit, like a joule thief. Something like the YX8018 (link to datasheet) joule thief would be amazing, as it protects the battery cells as well. However, I was unable to find a similar solution for higher powers/current that allows for day time use (YX8018 charges the batteries when solar input power is available and turns on the LEDs otherwise).
Is there a market available solution for this that I don't know of or do I need to design a circuit myself?
I have little experience building these kinds of circuits, so I am hoping someone could point me in the right direction on this. If there is an easier solution, feel free to add it!


texts: Using 2 7800 series regulators to get -ve, GND and +ve voltage rails

texts: I was wondering if there is a way to use 2 linear regulators in series to get positive, GND and negative rails. For example could you connect 7805s to get outputs like drawn? This is more of a thought experiment than something I actually plan to do (I'd just use the power supplies at uni). Thanks


texts: How to select a MOSFET when using 3.3v / 5v Logic level

texts:
I want to control/dim a 12V LED strip. When using an Arduino,
I used a MOSFET IRLZ44N, and a 12V DC adapter - it works as
needed.
I wish to use same hardware to control it remotely; a Wemos Mini is used as an Arduino replacement for that purpose.
When using Wemos Mini, I get only 7.9V at Vds - which led me to ask this question, bearing in mind that Wemos has 3.3V logic, which is probably the reason since a lower Vgs is applied.

I'm trying to determine what I am not understanding using the datasheet and graphs, since for 3.3V-logic-based projects an FQP30N06L was recommended.

I do understand Vgs, Vgs(th), Rdson, Vds , but still - I can't understand, spec-wise, what to find in order to get a Vds of 12V for a LED strip.


texts: Expected power draw for same flyback converters with outputs connected in series?

texts:
Suppose I used a single DC power source as an input to multiple isolated DC-DC converters (i.e. flyback converters) and series connected their outputs to obtain a larger overall output voltage. If each converter circuit was configured the same, could I expect that the load would divide evenly among them (i.e. each converter would output roughly the same power and current)? My thought is that, since they aren't switching in-sync, there would be differences in stored energy among each converter's output cap? If so how different or how would I find the max expected current draw from any converter?

The reason I ask is because I was looking into building a flyback converter and I was following this app note: http://www.ti.com/lit/an/snva866/snva866.pdf and
when calculating parameters relevant to choosing a transformer, I ended up calculating a large peak current for the primary side of the transformer. From equation 8 in that app note, this is primarily dependent on max output power and minimum input supply voltage. Anyway, it seems that a large primary side current limits me to a small selection of relatively large [in size] transformers. So I'm thinking if I can bring down the power requirement by my idea above, then it will ease in transformer selection.


texts: What is meant by "DC operating point analysis" in SPICE programs?

texts:
Here is a paragraph I came across:

  Since transient analysis is dependent on time, it uses different
  analysis algorithms, control options with different
  convergence-related issues and different initialization parameters
  than DC analysis. However, since a transient analysis first performs a
  DC operating point analysis (unless the UIC option is specified in the
  .TRAN statement), most of the DC analysis algorithms, control options,
  and initialization and convergence issues apply to transient analysis.

As far as I know the traditional transient circuit analysis is done by Laplace transform which superpositions both transient solutions and steady state solutions.

But when it comes to SPICE, for high speed calculations it uses different techniques and algorithms to solve circuits which are very alien to me.

I know about Laplace transforms and circuit theory but I'm curious how SPICE solves a circuit(as a big picture)? I'm totally blank about it.

Can the flow of SPICE be explained in an easy manner as a big picture?
What is meant by DC operating point analysis and what is UIC ect.?
When we run transient analysis what does SPICE do comparing to a traditional circuit analysis on paper?


texts:
I have built this ID sensor for a Scalextric slot car track, based on a PIC12F629. The ID sensor sends the ID of a detected car as a RS232 signal on one pin (TTL level).
My question is, how can I receive data from like four of these micro controllers into another micro controller's (PIC18F2550) USART?
I came up with these possibilities:

Just connect all of the serial lines "directly" to the RX pin of the PIC18 and  hope that two cars doesn't pass any sensor that close in time so the signals are overlapping each other. This could actually be a good start and will probably work 99.9% of the time. I mean, the mathematical probability that two cars are detected that close in time cannot be worth the effort of the other suggestions...after all, it's a hobby project.
Implement a busy signal that is raised when the ID sensors sends data and checked before sending.
Add some fancy multiplexer chip that eats the serial signals and outs them on a single line.

Each ID sensor chip will be coded with an identifier that is sent as part of the data, so they can be separated at the receiving end.
Update: Added some more info about the sensor hardware.


texts: CAN bus on bread board without 120 ohm terminating resistors?

texts: I have developed a CAN bus between two STM32s on two breadboards. My transceivers are MCP2551 ICs. I have faced something weird, the transfer of data becomes possible only when I remove two 120 Ohm terminating resistors. This made me curious to explore the reason of it. Please share your Ideas. Thank you.


texts: On high voltage power lines, what is "residual power"?

texts:
In a television show, high voltage power company workers were helping an animal to safety which climbed up a tower carrying high voltage power lines. The commentator said that though the power was shutdown but still the 'residual power' will be fatal to the rescuers and animal.

If that is correct, what is residual power? How it becomes residual? Or is it just a myth? Does it some how relate to static electricity?

I had attempted to search Google and this site for the answer and could not find any.


texts: How to light a strip of 32 LCD backlight LEDs

texts:
Ok, for starters I haven't been able to find a lot of solid details about the LEDs I have here. All I know is that there are 32 of them; 8 LEDs per strip, in series, and 4 strips, each also in series. Through my poking and prodding, I've managed to determine that the LEDs are probably around 3.6-3.7v and 150mA. The power circuit board in the TV was very well labeled and it specified 118V and 260mA at the LED connector, so I have to assume that means that each LED gets 3.6875v and 260mA. Unfortunately, the power board was broken (which is probably why the TV was in the dumpster...)

So, my question is, how the heck can I get 118v and 260mA? My initial thought was to use a resistor and rectified AC voltage from the wall, which would give me around 170v. That wouldn't work though, because $$\frac{(170 - 118)}{260} = 200Ω$$ and $$0.260^2 * 200 = 13.52W$$ Good luck finding a resistor that can handle 13.5W, and that's SUPER inefficient.

I have a basic understanding of electronics, but this kinda stuff confuses me for some reason. I'm learning more every day, I'm just stuck figuring this out. What would you do in this situation?

Edit: If it helps at all, I found one of these in my parts bin:

https://www.fairchildsemi.com/datasheets/FQ/FQA11N90_F109.pdf

900 volt N-channel MOSFET. Could this be useful?

Edit 2: I bought a DC-DC buck converter, 1.5-30V adjustable. Hooked it up to 32V, adjusted it down to 28 volts, then hooked it up to one of the light strips. 3.5V each and it's using around 200mA. Oddly, when I put more of the strips in parallel the current doesn't increase linearly. All 3 strips only draws about 400mA.


texts: Is it safe to run a PC fan with power low enough to stall it?

texts:
I have a "6V 4.5W" solar panel (Generic) and a 12V PC cooling fan (Evercool PWR-1225H12B) that consumes 450mA at 12V full speed.

Running the fan directly from the solar panel in full sun works decently; enough to push air at an acceptable rate. It is a "permanent" setup, with the fan and solar panel always being connected.

My question is: Would there be a premature aging issue to either fan or panel if there is only partial sun?

There is a bit of hysteresis because it of course takes more power to start the fan than to keep it running. So if it stalls, it can stay stalled for quite some time before it gets going again (if at all before next sun-up).

I think the panel will be fine, as I've read that short-circuits are not inherently bad for them, so the increased stall current should be no issue.
However, I'm more concerned about the fan circuitry. Since they are designed to run from a regulated 12V supply, I wonder if the drivers will have an issue running with only partial power and a stalled fan.

I realize that it can depend on the specifics of the fan I'm using, and that the innards are not disclosed. I imagine the fans are typically similar though, so anyone who has an understanding of how a typical PC fan works may be able to shed some wisdom as to why it would or would not be an issue to stall a PC fan for extended periods.


texts: My IC keeps blowing up - PAC1720 current sense IC

texts:
I am using a PAC1720 current measuring IC to measure the current/voltage/power being delivered to a lead acid motorcycle battery that is being charged.
Here is a newer datasheet and an older datasheet (with different info in them!)
Everything seems to work okay until I remove the power supply to the PAC1720 chip.  When Vdd to the PAC1720 is removed (i.e. my PCB power supply is off), it appears that the chip begins conducting current from its sense pins to the Vdd or GND pin (or both, not sure), which ultimately fries the chip.
This is a critical flaw because it means that if someone hooks up a battery to my product without having the power supply turned on (highly likely to happen), the product will destroy itself.
Here is a schematic of how the product is laid out:

simulate this circuit – Schematic created using CircuitLab
I'm guessing it has something to do with the internal ESD strucutre of the PAC1720.
One datasheet for the PAC1720 shows a typical layout like this:

The phrases at the bottom of that picture disturb me.  It says:

Note
1: The device MUST be biased PRIOR to applying VSOURCE. Failure
to do so will result in damage.
2: The unpowered bias on VDD must be
greater than VDD, if VDD will be removed prior to VSOURCE.

I don't understand what they mean by "biasing the device"... sounds like they are talking about biasing the internal clamping diodes?
The second note doesn't make grammatical sense does it?  I don't understand what they are trying to convey in the second note.
Now, an older datasheet shows the internal ESD structure of the PAC1720:

This isn't very helpful since it just shows a generic box labelled "Edge-Triggered ESD absorbtion circuit" between the upper clamping diode on Sense1 +/- and GND.
So, my main question is: what is happening when I disconnect Vsupply while a battery/charger is connected and the PAC1720 starts smoking?
Any way that I can solve this problem now that the product is in production?


texts: Controlling the frequency of oscillation of SI530 VCXO

texts:
I am thinking of using the SI530 VCXO as a means to generate clock signal at frequency of 1.4 GHz.

But in the datasheet I do not pin which controls the frequency of oscillation. Can someone help!

Also I am thinking of using the output from this IC as clock input for EL16V IC for generating PECL compatible clock signal at 1.4 GHz.

Will it work?


texts:
How do I connect/use a 3 Wire Digital Scale Strain Gauge Weight Sensor?

I took it from an old weight meant for people. :)

The wires are red, black and white.

I found this, http://www.nerdkits.com/videos/weighscale/ ,but they use a 4 wire.

Thanks


texts: Bipolar transistor static forward current transfer ratio

texts:
My book (teach yourself electricity and electronics) talks about the

  static forward current transfer ratio ... ratio of collector current v.s. emitter current when we place the base at electrical ground

If the base is at ground, surely the PD between base and emitter can only be zero or the emitter is at a higher potential? (Emitter can't have a potential lower than ground right?). In which case there is a zero or reverse bias at the EB junction so surely no current should flow? I must be misunderstanding something, can anyone show me the light?


texts: Efficiently Boost voltage for small single burst of current

texts: How can I efficiently boost 4.2v ~ 3.0v from a battery up to 5v for a short burst of current? My load is essentially an RC circuit with 17.8R and 300uF that I need to charge as fast as possible to function properly which is roughly a 281mA peak that quickly tails off.


texts:
What is the difference between 3 and 4 Pin IEC320 C14 Power Sockets?

Looking at the picture attached from reseller I cannot see what the 4th pin serves and I cannot find a description anywhere short of just buying one and figuring it out.

Perhaps the fourth pin functions to be always live even when the switch is off?


texts: Low frequency level shifting using single supply opamp

texts:
Referring to this discussion, I want to ask whether this can be done using single supply?

I have a similar problem where my input is a triangular wave swinging between 130mV and 500mV at 250Hz frequency.
I want to scale this signal in 0V to 5V range.

I do not have an option of using a dual supply so using a single supply opamp AD829.


texts:
We have a cabinet which is flushed with dry air and the metal instrumentation inside it tends to build up an unwanted charge. Obviously parts of the machinery are not sufficiently earthed (working on it).

However, is there any kind of sticky conductive tape coated with spikes/needle that might act to ionise the air and self discharge?


texts:
I was about to put a battery charging circuit into my schematic, when I read up on my MCUs VBAT pin. Quoting from the Datasheet:

3.9.6 Battery Operation: "An internal VBAT battery charging circuit is embedded and can be activated when VDD is present"

How can a miniature MCU handle battery charging? Have I missunderstood what they're trying to say?
Also, there is a table (page 26) of which peripherals are available during VBAT operation, and almost all of them are unavailable, does this mean I should implement my own charging circuit and just disregard the VBAT pin altogether (connect it to VDD)?

There is just one feature that is worth connecting the battery to VBAT pin, but I don't know how it will work when powered from VDD...:

3.15.3 VBAT battery voltage monitoring*" This embedded hardware feature allows the application to measure the VBAT battery voltage"*


texts: How to add CC/CV feature with single LM358 for variable linear power supply?

texts:
I have a few weeks with a problem in the design of my bench power supply. First of all I have this design from this guy on YouTube https://youtu.be/_CFIovMkRyg that made a variable power supply using two of four op amp LM324 and the PSU behavior is really stable perhaps I don't find a way to get work that design in LTSpice.
Here's a snapshot of the video showing the design he used.

Here's I've tried so far in LTSpice.
Darlington PSU.asc
I think is a reference ground problem because he has two grounds. When I simulate all the current from the current source is sinked by a single OPAMP and doesn't matter the value of the pot wiper the control doesn't work. In any case Does this design really work? if it doesn't work, you know a way to make it work?


texts:
It may seem like a stupid question. I'm new to pcb design. I designed a trace similare to the following picture (Excuse me for poor graphics)

My PCB trace is like the left picture, now when current flows how do electrons flow? I'm a mechanical engineer so I imagine it should be something like flow of a fluid as I've shown on the right picture. If it's so the sharp corners do nothing! Can somebody please explain that to me?


texts: Unspecified I/O Standard value 'DEFAULT instead of User defined value. But I can also not assign a value

texts:
So I'm totally new to this and sorry if this is a really basic question which answer is in the error message.
I get the error:
[DRC NSTD-1] Unspecified I/O Standard: 5 out of 25 logical ports use I/O standard (IOSTANDARD) value 'DEFAULT', instead of a user assigned specific value. This may cause I/O contention or incompatibility with the board power or connectivity affecting performance, signal integrity or in extreme cases cause damage to the device or the components to which it is connected. To correct this violation, specify all I/O standards.

I know which pins are at fault but I cannot assign them values directly: assignment to a non-net is not permitted.

I've been trying to fix this for a few hours and I'm quite at a loss.
I don't want to create a tcl file as it says this may damage the board and this board is quite expensive.

Also this happens when combining two modules.
The modules by themselves with the same code run fine.
Thanks in advance!


texts:
This circuit simulator called "iCircuit" for mac users is showing some weird readings. It's showing a reading of 2.4mA and i'm getting 6mA in my calculations for this circuit I threw up. Am I missing something here??

18V / (2k + 1k) = 6mA


texts:
I would like to know if there is a limit on voltage between gate and drain,
What happen if the gate voltage is over drain voltage.
I looked at datasheets but won't find anything.

Thanks


texts: Simulating keyboard strokes with shortcut key combinations

texts:
I rigged up a tiny little project using a scrap Dell keyboard, where I tore the keyboard apart and salvaged the USB control board. The actual keyboard is gone. Then, I traced the circuit for the "Enter" key on the keyboard, to figure out exactly which combination is needed to close the circuit to trigger "Enter", and hooked up a single button to it.

This works great, and I could presumably do it with any button.

However, I'm also interested in key combinations. For example, CTRL + SHIFT + R. All 3 of these circuits can't be closed at precisely the same time - CTRL + SHIFT needs to be triggered before the R key. So the same idea of a single button directly connected isn't going to work.

NOTE: I have relatively little knowledge of circuitry design, but have played around with it plenty.

What's a circuit I could easily create which can simulate this? I assume it should be as easy as a slight delay between closing each circuit, but I have no idea where to begin creating a circuit.

Ultimately, the end goal is to create a custom button panel where each button sends a key combination to this scrapped USB keyboard controller to simulate keystrokes.

To add a little more details, in case you're not familiar, the keyboard works like this (at least the one I'm using). The board has 27 contacts which are pressed against the actual keyboard sheets. 1 contact (AFAICT) is a ground, then there's a group of 8, and a group of 18. When a key is pressed, it closes a circuit between one contact in each group. So, for example...

[GND] - A B C D E F G H - 1 2 2 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

The "Enter" key is achieved by closing a circuit between E and 7.

I'd like to avoid any sort of microcontroller if at all possible. I recall in the past, seeing a trick with a capacitor and transistor, which could achieve a delay.


texts: Frequency + Fourier Transform Notation Question

texts:
Continuous Time Fourier Transform is notated as \$X(j\Omega)\$

Discrete Time Fourier Transform is notated as \$X(e^{j\omega})\$

can someone explain the difference in notation?


texts: How to calculate distance between two wire-pcb connectors with high voltage for keeping connectors isolation?

texts:
I'm planning the way of connecting 8 devices terminal wires all together within a 6kV point (V+), there will be 8 more wires connected to GND (V-). Those V+ and V- points will be in the metal case. The key is how to join 8 wires in an only point inside the case.

I thought bringing V+ and V- (that comes from external source to the case by 2 jacks) until a PCB with only wire-PCB connectors. No more proposal for this PCB.

I have not any experience at HV design, but I' ve learnt some tips and tricks. I have read all the literature that I can.

Searching components, I have found there are wire-pcb connectors that supports until 2500V (wurth). If I understand correctly, this breakdown voltage is refered to the voltage difference that could be supported between pins or closer connectors before isolation falls.

My suggestions:

So if all the connector pins has 6KV --> Vpin1 - Vpin2 = 0V < 2500V will be ok.
So if some connector pins are 6KV and other one is 0V --> Vpin1 - Vpin2 = 6KV > 2500V will be a problem and probably it will fail.
But, I know that E = V/distance and this has much to see with dielectric strength.

Taking the suggestions into account, guessing they were true, I will launch my two question according to the dielectric subject:

1.- Could I separate them -GND connector from 6KV one- some distance between them in order that voltage doesn' t break connectors isolation?

2.- If answer is "yes"; how to calculate mathematically the air gap/distance between two connectors that will support 6KV knowing that they can support 2.5KV?


texts:
I understand quartz crystal oscillator quite good, but there are two things I am not clear with:

When quartz crystal wafer is squeezed, at that point, does it generate unlimited current capability? Or does it have to be expanded for the same amount as it was squeezed to again produce same amount of current but in reverse direction?
How do you actually generate some resonant frequency (e.g. 16MHz) with XO? I meant if you mechanically swing (expand and squeeze) it with one frequency along x-axis, it will generate the same frequency along y-axis, will it not?


texts: Use audio frequency to light up multiple LEDs

texts:
Need some help here - I need to light up about 20 different LEDs based on the frequency input(200 Hz-20,000 Hz)

Eg:

  The circuit should light up the 1'st LED when the input frequency is
  between 200 Hz and 300 Hz

Similarly:

  The circuit should light up the 2'nd LED when the input frequency is
  between 500 Hz and 600 Hz

And so on...

I thought about using a band pass filter, but I don't think it would work with frequency ranges tight as these.

  Below is the band filter I used to try out filtering 11,000 Hz -
  15,900 Hz

but the LED lights up even on 9,000 Hz.

  Band Pass Filter Graph

What can I do to get this done?


texts: I have a Mac Mini and a PC. Every day, I remove the HDMI wire, mouse, and keyboard wires and I connect them to my Mac Mini. I am constantly plugging wires into my USB ports. Will that harm my computers over time? I make sure that the computer is off before I remove the plugs.


texts: Identifying source and drain terminals for MOSFET circuit

texts: This is a circuit  exercise from Razavi's book. He used to point to the direction of current leaving the source in his circuit for N type of MOSFETS. But here, I think the drawn arrow refers to the current leaving the drain. Now I am confused, why he made it like this? Is this even NMOS or PMOS?! Which method should I use to distinguish between source and drain?


texts:
I am in the middle of making a small USB & LAN pass through PCB (a small add-on PCB for a larger project.)

I have some problems getting it to work properly. It is quite simple - it takes a USB signal from one connector to another, and that is that.

I know USB needs 90Ohm differential impedance (+-15%.)

The layout looks like this where the 2 highlighted lines are the USB data lines:

The PCB is a 0.8mm board, and for getting 90 ohms I have the differential trace to be 0.8mm wide with 0.2mm space - that gives me 83.605 ohms which is well within the 15% tolerance.

What can else be a problem with the layout? I kept the track on the bottom side of the PCB to avoid unwanted stubs on the connector.


texts: MP1584 step down short circuit efficiency

texts: If I use MP1584 step down IC and short circuit appears how can I calculate the efficiency or the total power dissipation for the IC?


texts: Is it possible to help accelerate a starting motor externally?

texts:
I have a rather small motor and a matching energy source.

When the motor starts, it needs a (short) amount of time to 'rev up', to accelerate at its max speed.

Is there any cause for this other than mechanical inertia and friction? Would, say, a pullcord attached wound in the rotation's direction, pulled as the motor start, serve to bypass this delay?

Please explain it like I'm five (but good at googling terminology).


texts: What does a denormalizing and normalizing a capacitor mean? I am confused with  the difference of normalizing and denormalizing a capacitor.


texts: Connection to ground for a Cat5e Shielded outdoor rated cable

texts:
My ISP installed the cable modem in my entertainment room.  I am trying to have internet also in my STUDIO with an access point to broadcast a second WIFI from there to other parts of the house. (My property is big, with 2 floors, and concrete walls between since it is an old construction (50's) which decrease the performance of Wireless extenders, AP, etc (I tried everything, even Ethernet over power lines).  So, now I think I am left with running a Shielded Outdoor rated CAT5e from that entertainment room through the wall, then outside the house running up to the second floor and again entering the house through a hole to the STUDIO.  My question:

I have read that I have to ground any copper cable running outdoor before entering the house.  So, the GROUND ROD for my MAIN electrical box is next to the house, in a wall NEAR to my entertainment room (where the cable modem is located), so, I guess I can install an ETHERNET SURGE protector with ground connection that side of the house (exterior installed) to the MAIN GROUND ROD.  But what about when the CAT5e enters the house AGAIN in the second floor from outside through another hole in the Studio?  Do I have to install another ethernet Surge protector and run again a LONG ground wire from there to the Rod downstairs which is around 120 feet distance far?  Or, Is it ok to connect the cat5e cable to ground just in one point (the point leaving the house from entertainment room downstairs) which is near the MAIN Ground ROD of the HOUSE?

Thanks for advise.


texts: Relation between Amps and Thickness of wires

texts:
I have some questions that have been bugging me for the past few days, and I am here in hope of some help.

My Understanding of how battery works: "The battery (say 9V DC) does not store charge, it just provides voltage for the electrons in the wire to flow, causing current."

Q1) If my understanding is correct, the amount of current (AMPS) should depend on the thickness of wire, as there are more free electrons available. Is this true?

Q2) If I short the two terminals of a battery (9V DC) using a wire (of almost zero resistance) why would the wire heat up and burn? If I had used a thicker wire would the current passing through any point in the wire be greater than if I had used a thinner wire?


texts: Better Techniques/Equipment for BGA Soldering

texts:
I've recently been soldering ball-grid-array parts to boards. This is relatively new to me, and there has been a few mishaps with my technique. I was just wondering how does the community perform BGA soldering? What techniques/equipment do you use to make this process more efficient and less error prone?

My technique involves using a Hakko FR-830 Preheater to do the work. I use an old board holder to hold my board in place, and then I apply some solder to the board using a syringe (ChipQuik SMD291AX). My part is a 6x6 BGA array, with the pads 1mm apart from each other in a square grid. Once I place the solder onto the pads, I slowly put the part onto the pads, aligned as close as possible. Then, once it's ready, I turn on the preheater through its temperatures from 150-300 degrees Celcius at 50 degree intervals for about a minute and a half at each temperature. The apparatus is not enclosed, so I put a piece of metal over my board holder so that the top of my PCB board is not exposed to open air.

My process is not exactly ideal, but thus far, it works alright. However, I noticed that the solder doesn't seem like it really 'melted'. I think that this might be because of my methods, and running a hot air gun on the sides doesn't really help much. Any tips or suggestions? This is all done in-house, and I have to do this by myself, so learning how to do it better would be helpful.


texts: Analog Audio Signal over dedicated Ethernet/Twisted Pair Cable

texts:
I need to send an audio signal over 3 meters and back again on the same line (the plan is to put an on/off switch and a volume regulator at the end of the line).

Additionally I would like to send 12 volts power in the same cable, with small amperage.

Is it possible to use an Cat5 Ethernet cable for that purpose? I have those in abundance, and want to avoid buying a dedicated cable for that purpose.

I would use following signals:

Audio Right In
Audio Left In
Audio Ground In
Audio Right Out
Audio Left Out
Audio Ground Out
12 V +
12 V -


texts: Help designing a circuit to drive a 1550nm DFB LD and use it to modulate an RF signal

texts:
I need to modulate an RF signal (random sine wave acting as data) using the 1550nm DFB Laser Diode, I need a control circuit to drive the Laser Diode and inject the data to modulate the LD carrier wave. I won't mind if you provide me with the complete circuit just as long as you can explain to me step by step the purpose of each part of it, I'm sure this break down will help those that read this to benefit from this question.

The carrier would be the optical wave and the source signal will be an analog continuous wave, i will be using a function generator to create this wave. This means i will modulate the optical wave using the analog wave and carry the modulated wave through a single mode fiber, at the other end i will have a Photo diode and an oscilloscope to see my original signal.

I will be using a function generator to create the RF signal so there is no restriction to the frequency i can use, it can be low or high. The specs of the LD say that the max operating voltage is 1.7V and the max operating current is 90mA. Since i am not sure what else is needed i can provide more information if necessary,the LD is WSLP-1550-008m-9-DFB.

Thanks in advance.

Datasheet
https://www.dropbox.com/s/00ga6umtnw6re3d/WSLP-1550-008m-9-DFB.pdf?dl=0


texts:
I was trying to understand the ripple effect in asynchronous counter and I came across this figure:-

In all the problems solved in my book, they consider the minimum clock period required for proper functioning of counter as the sum of the delays caused due to these flip flops.

If we consider each delay as 5ns in the figure then the answer would be 15ns (minimum clock period time) according to my book.

My doubt is if it is exactly 15ns, then after 15ns, Q0 will toggle and we would get "1". So at the end we can't get 1000 as output as by that time Q0 would have toggled and we would get 1001 skipping 1000.

So I don't understand how clock period of 15ns would solve the problem of rippling.

Can someone please help me understand this concept?

ref:- https://www.allaboutcircuits.com/textbook/digital/chpt-11/asynchronous-counters/


texts: How is the state of a bit position on a hard drive measured?

texts: Firstly, I am not the EE type, but I do have a petty good foundation on physics work on a pretty low level.  I was wondering what mechanism it is that measures the magnetic indentation on hard drive platter (if that's even the case), and/or the specifications and variances that determines a 1 or 0.


texts: Accurately amplifying a number of current sense transformers

texts:
I've got 16 current sense transformers that are being used to monitor AC loads. The SCTs are current output type, producing 50mA on a 100A load. The maximum burden resistance is 10Ω, thus the voltage signal generated from the voltage drop over that resistor is ±50mV. I'm feeding these outputs into an ADC whose input range is 0V to 5V.
While I could technically DC offset this ±50mV signal and feed it directly into a 12-bit ADC, this wastes a ton of the measurement range and leaves most of the signal behind under the noise floor of the ADC. I'm trying to figure out a way to bring the 50mV bipolar sense signal up to somewhere around ±2.0V centered around a 2.5V DC offset, without losing accuracy or running into offset issues.
I've seen other designs buffer the signal and send it straight to the ADC, but those designs also make weird decisions like not using rail-to-rail amplifiers, and adding 20Ω or even 30Ω of burden resistance to the SCT, presumably to increase the voltage range, but this is way in excess of the rated maximum in the SCT datasheet. In short, I don't trust them all too much when it comes to accurate results.
I currently do not have negative supply rails on my board, so my first thought is something like this:

simulate this circuit – Schematic created using CircuitLab
This is just for reference - the exact opamp would be something other than the TL081, and the D1/R2 part of the circuit would be implemented via a voltage reference IC. The idea is that the 0.0625V reference voltage biases the burden resistor (R1), such that the signal going into the opamp has a range of 0.0125V to 0.1125V. The opamp then amplifies this by 40x, resulting in a range of 0.5V to 4.5V.
My primary concern with this approach is that any input offset voltage in the opamp would cause problems when multiplied by 40. Same goes for any variance in the DC bias reference voltage.
My other thought would be to use an instrumentation amplifier and feed its output and a DC offset voltage to an adder circuit. It means biting the bullet and adding a negative rail to the board, but it's probably a more robust solution. Here's a rough schematic:

simulate this circuit
The instrumentation amplifier is likely to have a much smaller overall offset voltage, and since we're only amplifying the input signal by 40x, instead of both the signal and the DC bias, my guess is it'll perform better. OA1's offset voltage is less of a concern, partly because it is relatively low by comparison to the voltage range of the signal, and also because it is a constant that can be measured and accounted for in software. The TLC2274A seems like it should work ok - common mode voltage specs seem ok, and its max input offset voltage is 950µV.
The problem with the instrumentation amplifier approach is that I need 16 of them, plus the additional opamp for the voltage adder, so that increases costs somewhat. Using a 4-channel opamp does help somewhat here, since it's then just one IC per channel, but it's still a whole bunch of them.
Am I thinking this through correctly? Am I missing a cheaper solution that gets the same level of accuracy?


texts: Plot Stepped Measured Data is disabled at Spice Error Log LTspice

texts:
I'm following the example from the top answer of this question.

Here below I exactly do the same thing:

But when I right open Spice Error Log (View -> Spice Error Log), and right click on a place as you see the "Plot Stepped Measured Data" is disabled.

How can I solve this issue?


texts:
I need help identifying which wire is which inside my USB cable. So I stripped the outer insulator for the USB cable, and it revealed 4 wires: Red, White, Green, and Yellow.

I thought Red would be VCC, but then I checked the circuit board for the mouse I ripped it off of and the board labeled where the four wires were soldered on.

It showed four characters each associated with a wire color: V (White), G (Green), D (Yellow), C (Red). Very strange from what I have learned about USB so far, but strangest being that Red is not VCC! Why is there no standard for these wire colors?

Anyways, how can I confirm which is which (VCC, GND, D-, D+)? I have a multimeter, and confirmed that between White and Green, White and Red, and White and Yellow, there is 5V. I don't think that is much of a development, but what should I do?

I do have other USB cables lying around as well, but that's an easy way out and my absolute last resort. Thanks.


texts: Why should Q not exceed 1/2 on a 2-stage filter?

texts:
I am just starting on filters.

I've seen on a tutorial that says 2-stage RC filter Q could not exceed 1/2. Could someone give some explanation?


texts: Can I power LED strip without ground wire?

texts:
I have this power supply:

And this, which has 2 wires coming out:


texts: I have to do a lab report which requires me to know the value of the base emitter voltage of the BJT in the forward active region.  Last week in lab I measured a lot of data points for different Ib Ic and Vce.  From this I determined my beta to be about 208.  Now for the report I need to determine a value for the voltage drop from the base to the emitter (also I am using an NPN BJT).  I am not so sure how to do this (or even if it can be done given my data set).  I tried solving a system of equations relating Ic to Is and Vbe however I quickly realized that these equations could not be solved for Vbe.  Any advice for how I can go about it?  I also have values for beta forced and Va but I don't think these will help.  The directions in my lab are not very clear so I am unsure if I even need to find Vbe or if I can just use the standard value of 0.7 volts.


texts:
I have a very basic question here. When I learnt Processes it was said the statements occur sequentially.This is what I believed in. In the NCO process image file,there is proof for it. fword is assigned with a value and nco_acc is incremented in the next statement and in the third clk_pn is assigned. In the second image file,the corresponding synthesis results have been given. When reset goes low,fword gets its value in the first positive edge of the clock and in the next edge nco_acc is incremented and in the next edge clk_pn is assigned the msb of the nco_acc.                                                         Till here no problem. Then I met another problem.In the other image there is a process highlighted. here too there are two statements inside the process statement in the else part. But it happened concurrently. The statements occurred in the same clock cycle.

What should I conclude?

When is it sequential and when is it not?

NCO:process(clk,reset)
          begin
            if (reset='1') then
              clk_pn<='0';
              nco_acc<=(others=>'0');
              fword<=(others=>'0');
            elsif (rising_edge(clk) ) then
               fword<=fword1(conv_integer(outp_sm));
               nco_acc<=nco_acc+fword;
               clk_pn<=nco_acc(nco_pngen_res-1);
            end if;
          end process NCO;

  process(reset,clk,car_change)
        begin
         if reset='0' or car_change = '1' then
            g2codereg <= "1111111111";
         elsif clk'event and clk='1' then
            g2codereg(1)           <= g2codereg(2) xor g2codereg(3) xor
                                    g2codereg(6) xor g2codereg(8) xor
                                g2codereg(9) xor g2codereg(10);
            g2codereg(10 downto 2) <= g2codereg(9 downto 1);
         end if;
       end process;


texts:
This is my ISELED Driver Datasheet INLC10AQ & my Microcontroller datasheet S32K142 - 64 pin Microcontroller
I have a NXP Microcontroller connected to the above LED Driver. I need to figure of the type of protocol that is used for the uC communication and the LED Driver.
In the first page, 3 paragraph of the product description, it is mentioned like " A proprietary bus
protocol is used" and in first page, features section the datasheet mentions "Bidirectional, half-duplex, 2Mbps, CRC protected serial communication"
It is also mentioned that the communication between the uC and the first LED Driver is single ended. The type of serial communication between the uC and the driver is given in, Figure 9 - "Single ended downstream command frame"
My questions :

My uC pin has LPSPI module , FlexIO module, FTM Module & GPIO module capacbility. Which module module usage will help me with the communication between the uC and the pin 7 & 8 of the LED Driver.

My thinking is, since the serial protocol is used for the communication and the pull-up is required for the communication lines, may be FLEXIO module must be used at the uC pins. Or can the protocol communication be established just by using GPIO module at the pins and perform bit banging?

Is the single ended serial communication between the uC and the LED Driver one-way communication (simplex)? Because no Voh values for single ended serial communication is not provided in the LED Driver IC datasheet. Why is that?

But in the first page, features section, it is mentioned as bidirectional half-duplex serial communication. So, there must be communication between the LED Driver and the uC, right? If then, What value of Voh should I consider for the single ended serial communication?


texts: Is the hFE of a bipolar transistor independent of Vce?

texts:
In the datasheet they express the hFE for a fixed Vce, sometimes they put 1v other times 10v, but if the gain is independent of Vce this data is not really important, the hFE indicated in the datasheet is valid for the Vce that my circuitry precise?
Thanks


texts: Why are there uninsulated strands of wire in this sensor cable?

texts:
This is the cable coming from an SCT-013 current transformer current sensor. I don't understand the purpose of the bare wire strands that I have twisted and bent away from the rest of the two wires (they were previously all around the two wires).

Are they important? If I need to connect this sensor to a microcontroller, what should I do with them?


texts: What can I use to detect pinpoint location (inches) outdoors?

texts:
I am getting back in to EE after some time so please excuse my ignorance. I am looking for a way to detect pinpoint location outdoors to navigate a robot for a project with my sons.
Is there a low cost way to triangulate or use GPS? I am looking for down to the inch precision. Also I do not care if I need to place some transmitters in different locations to give the device a reference.

This is for a robotic lawnmower. I have a 2 acre yard and my house is near the middle with several trees as obstacles.

Two of my three boys (14yrs, 11yrs, 5rys old) brought up the idea so the real goal of this project is to spend time with them and pique their interest in EE & CE.

With that said cost is a factor but I do not care if we work on it for the next 2 years and spend a little along and along.

Here are my current plans

Include a Windows PC on board so I can code against the sensors.
Microsoft Connect on board to help with obstacle detection (reason for Windows PC)
Include a USB GPS for general location
Include camera just for the fun of it

In 2 years if I have some money in it that is okay but I do not want to start with a crazy expensive GPS.

Thanks to everyone who has help me!!!!


texts: LM317 µA Constant Current source possibility?

texts:
I want to create an adjustable µA Constant Current source using a LM317. It is typically stated to have a 5mA to 10mA minimum current for proper regulation. The On-Semi version linked above shows a graph where this actually depends on the Vin-Vout differential. Even then, I'm looking at 2mA minimum, which is higher than the 0.1mA I am looking for. While looking at circuits of a typical regulator constant current source, I came up with an idea, and am not sure if it will work properly or not.

Since the circuit depends on Iout being shared in a series circuit, and only cares that voltage drop across R1 equals Vref (1.25V), wouldn't a second circuit, parallel to R1, allow for a greater total current draw, but still allow for voltage regulation dependent on R1? My idea (Note: RRef would be an adjustable trim pot, 12.5k just a reference value for now):

simulate this circuit – Schematic created using CircuitLab
Since total Vout should be VRef + Vload, then Vout / RDummy = IDummy (For VOut 3~9 Volts, that's 10~27mA). The Led Load part should still only get 0.1mA (plus another 0.1mA from IAdj, this is okay) as desired.
Is there any reason this would not work?
I'm assuming if it will, then by paralleling the R2 and Led on a third circuit, that I can avoid the IAdj current as well?


texts: Keeping voltage above 3.7 Volt with a lipo

texts:
I am driving an audio amplifier with a 3.7V lipo.

With a  latching circuit in front.

[![enter image description here][1]][1]

The problem is, that when I turn up the volume,
the voltage drops under 3.7 volts (especially on bass) and the amplifier turns off for a couple of milliseconds.

The amplifier accepts 3.7 - 5 volt.

What is the simplest way to keep it above 3.7 volt?
(I think that is the problem.)

I think it needs some sort of voltage regulator.

When I plug in the lipo direct into the amplifier(without the latching circuit) I can turn up the volume to max.  But only as long the lipo is nearly fully charged.

Isn´t it possible to somehow put a large capacitor in, to buffer the short voltage drops a bit ?


texts: What are the differences between a VESC and a E-bike controller?

texts:
I'm trying to figure out how do a VESC and a generic e-Bike controller differ?
Besides the custom controls and the higher rating of the VESC are there any other differences?
Parts:
The Vesc:

3-12s battery
50A continuous
150a max
£56

The E-Bike Controller:

10-12s battery
22A continuous
35A max
£17

The hub motors:

75kv
90mm diameter
36v
600w max power
£130

I want to get these two hub motors and 2 e-bike controllers and use them on my longboard.
My plan is to use the folowings:

2 e-bike controllers
2 90mm hub motors
10s2p using ncr21700
A custom remote out of a WII nunchuk using arduino and NRF24

I feel like im missing something regarding the controllers and I dont want to buy them before some confirmation cuz the postage take 1 to 2 months.


texts: When wiring a circuit with a capacitor why does the electricity go to the capacitor first instead of bypassing it?

texts:
I am relatively new to electronics and only dabbled in high school with very simple circuits but I was doing an led project with neopixels and they wanted a capacitor on the positive and negative rails to stop an inrush of current to prevent damaging the first pixel.

"When using a DC power supply, or an especially large battery, we recommend adding a large capacitor (1000 µF, 6.3V or higher) across the + and – terminals. This prevents the initial onrush of current from damaging the pixels. See the photo on the next page for an example."

The circuit above kind of shows what I mean, how come the electrons don't flow past the capacitor and too the led or is that a wrong assumption and electrons do flow past the capacitor and the capacitor just takes some of the energy?

If the electricity has to charge the capacitor first than what is stopping the current going past the capacitor.

I hope I worded that well. I apologise if I am not getting my point across.


texts: Timer IC that doesn't reset count because of power down and remembers last state

texts:
I'm looking for a timer/RTC that will count how long the system power was up in total and will toggle a pin after a specific time that will be configured in advance.
Does a timer that "remembers" exists?

For example, on the first time that the system is powered up for 2 hours, after this it's down, and powered up for 1 more hour, so in total the timer will be already 3 hours, etc.
After 500 hours (for example) I'd like to toggle a pin that will notify this.

The time resolution can be even hours, but I don't want to use a microcontroller (except for initial values configuration) or a battery (or supercap because I don't know for how long it will be down).

My main purpose is small size and less components, Power consumption is not an issue.

Thanks,

Avi


texts:
I just made something cool (or at least in my mind it is), and I wish to save it under the form of a schematic. So I started making one with CircuitLab.

The circuit includes a shift register chip (74HC595N), which I couldn't find on CircuitLab. Is there any specific drawing to represent a shift register on a schematic ?


texts: Displaying a custom character on 2x16 LCD

texts:
I have written a working LCD driver for a NHD‐0212WH‐ATGH‐JT and I would like to add the possibility to create your own custom characters.

Through some research I understood that I need to write a byte for each row in the CGRAM in specific positions and then point to that position when trying to write a character.

I did the following but it doesn't seem to be working:

The array of char for the bytes to write to CGRAM were obtained with online tools such as HD44780 LCD User-Defined Graphics. The functions and commands don't seem to be the problem as I write every other ASCII characters just fine.

char myCustomCharacter[8] = {0x0,0x1,0x3,0x16,0x1c,0x8,0x0};

void createCharacter(unsigned char location, unsigned char[] bytes){
    writeCommand(0x40+(location*8));
    writeData(bytes[0]);
    writeData(bytes[1]);
    writeData(bytes[2]);
    writeData(bytes[3]);
    writeData(bytes[4]);
    writeData(bytes[5]);
    writeData(bytes[6]);
    writeData(bytes[7]);
}

Then in some test main:

int main(void){
    initLCD();
    createCharacter(1, myCustomCharacter);
    setCursor(0, 0);
    writeCharacter('A'); //This work just fine, the A is displayed as expected
    writeCharacter(0x08); //Doesn't work, I don't see the character I stored in the CGRAM at the 1st position. Any standard ASCII character still works just fine.
}

How do I access the custom character as if it was just another ASCII character and how do I know I have correctly written the byte into the CGRAM?


texts: Can you buy Aluminum Nitride transistors?

texts:
We all know wide bandgap semiconductors, currently galium nitride and silicon carbide are the superstars becose many companies make them at relatively reasonable price. They aren't just mere lab curiosities but very real choices.

There are also many more wide bandgap semiconductor materials with even higher bandgaps such as diamond, silicon nitride, boron nitride, silicon dioxide and aluminum nitride a.k.a. AlN.

I read on wikipedia that military uses AlN transistors, which means they are actively produced somewhere. Do you know any manufacturer that makes AlN transistors? I want to know if there is currently any commercialy avaliable AlN transistor.

Last thing I want to add to prevent potential mistake, aluminum nitride have also high thermal conductivity, it’s a frequent substitude for toxic beryllium oxide used in transistor as heat spreader thermal material. I am looking for transistor that uses it as semiconductor, not as heatsink.


texts: Piezo electric transducer-Vibration to Electrical Energy

texts: I need to convert Vibrations into electricl enerery. Is it possible to convert it with the use of single chips?


texts: Should a D Flip Flop store its input on clock rise?

texts:
I've seen conflicting descriptions and conflicting implementations of D Flip Flops, when it comes to how the Flip Flop behaves when its input value changes at the same time the clock rises.

Implementation #1:

[CLK] [IN] [OUT]
 0     1    0
 1     0    0

Implementation #2:

[CLK] [IN] [OUT]
 0     1    0
 1     0    1

In other words, Implementation #2 will always store the value that [IN] had during the first half of the clock cycle, but Implementation #1 will pick up the value of [IN] on clock rise.

Which implementation is correct, or standard?

If I buy myself the most widespread Flip Flop model in a store, how is it likely to behave?

UPDATE:

The following implementation (in Digital) behaves like Implementation #2.

However, it behaves differently from how Digital's built-in D-Flip-Flop component behaves (it behaves according to Implementation #1).

Would you say that either implementation is correct or better?

Which implementation am I more likely to find in actual hardware?


texts: I've read an appnote from TI (slaa338) that describes a technique for generating "for real" (as opposed to "pseudo") random numbers. It exploits the somewhat exotic clock subsystem of the MSP430 to achieve this goal. Does anyone know of a technique that can be implemented on an AVR (I'm interested in the XMega's in particular) for generating "for real" random numbers?


texts: How do I convert voltage square wave signal to 4-20mA signal

texts:
At school we are looking for a sensor that is able to count/sense the rpm that the shaft is turning at.
I have found a sensor which does this but it sends out a voltage square wave: Datasheet

I need this converted to a 4-20mA analogue signal (higher rpm = higher current).

What would be the best way to go about this?

Thanks in Advanced!


texts: Why the GND is visible for 2 layer design in PADS layout?

texts:
I am facing an error while practicing a reference design of  DLP-2232M-G  board  downloaded from Mentors website.

The design engineer of this board has used 2 layer (TOP and BOTTOM ) keeping 3 to 21th layer inactive.
Take a look " layer setup", in both case he assigned GND at "Assign Nets".

After I made schematic in PADS logic and connect with PADS layout, I found GND trace exists on PADS layout design.

Take a look, 2 capacitors ends are shorted, they should be "GND". In this design, no layer for "GND" has been called.

If you feel any setting is necessary in "Design rules", let me know.

Thank you.


texts: Is it possible to send multiple data bits on a single wire at once?

texts:
Is there an existing protocol or modulation method where multiple data bits are sent over a single wire at once or maybe an additional ground line (like serial communication)?

I know there are methods like PSK or FSK where phase or frequency of carrier is altered to represent different bits or states of signal, but those changes in phase or frequency are transmitted one after another i.e. serially and not at once.

Is there an existing communication or modulation method or protocol which can send multiple data bits at once and not one after another using the shifting done in PSK or FSK?


texts: We have 4 negative feedback topologies;series-shunt, series-series, shunt-shunt, shunt-series. I'd like to know something where we use these topologies. What are advantages compared to their each other ?


texts: Hazards of puncturing lithium-ion batteries?

texts:
I was doing some electronics repairs, and accidentally punctured a small (mobile phone capacity) lithium-ion cell battery with a metal spudger.

At first, I hadn't realised I punctured the batteries - I noticed a funny burning smell, and I was like...huh? I turned the battery over, noticed some curls of smoke coming up, and smelt the burning smell again. That's when I was like, oh...c*ap....I disposed of the battery right away.

I feel fine now - no respiratory distress, or coughing, or anything of the sort. I've just rinsed out my eyes my clean water. (In hindsight, I probably should have done it immediately after disposing of the battery).

However, reading through MSDS for lithium ion batteries is quite a sobering read:

http://www.uscg.mil/hq/cg4/cg432/docs/msds/MSDS_LiIon.pdf

It's a Sunday, may see if I can pop into a medical centre later - not sure if this warrants heading into hospital's emergency department for.

However, my question is - has anybody here had any experience with lithium-ion cells? How hazardous exactly are the fumes if you puncture it? What exactly are the fumes/burning smell? (As in, is it lithium reaction with air, or some other by-product?)

Any residual effects or symptoms I should be very wary of? (Basically, if you see X, go to emergency etc.).


texts: Is a bq2920x enough to protect a two-cell Li-Ion battery?

texts:
I'm designing a battery supply to go into a bluetooth speaker. Having never worked with Li-ion cells before, I've done some research and understand that they need to be load balanced and protected from over-voltage or they explode.

I've found the TI bq2920x IC. Which they suggest using in this configuration:

Am I correct in thinking that building this circuit should be enough or is additional protection required?

My design must be able to output 5V and 1A.

I'd also appreciate it if someone could clarify if PACK+/- are the two power terminals and if OUT is the PSU output voltage?


texts: Purpose of capacitors and extra resistors in the feedback of the inverting op amp?

texts: I'm trying to fully understand this opamp configuration but i can't. The signal enters through R19 and i understand that is an inverting configuration and is attenuating the signal with a gain of G=1.2/7.5, but i cannot truly understand what are the functions of both capacitors and the resistor of 24ohm. I think the 24 ohm is a current limiter resistor, but why put in the feedback loop ? And i think the feedback capacitor creates a low pass filter.What would be the cutoff frequency of this filter ? Because in the literature of this circuit its written it has a -3dB frequency of approximately 198kHz


texts:
I don't speak English very well so sorry for the problems in the language.

I am working on a cardiac pulse meter, it is based on the changes of the flux in the blood that go through the fingers. The part of the solution that i have at the moment is a transducer and then a low pass filter (cutting frequency of 15 Hz). The operation range of the circuit is from 0.8 Hz to 3 Hz because that is the frequency of the hearthbeat. I need to amplify my signal so i wanted to add a OPAMP UA741 as an amplifier but it didn't work. The signal is really weak and after the OPAMP the signal dies.

Here a picture of the signal after the low pass filter.

Here a picture of the circuit diagram. Consider that model OPAMP is not TL081, it is UA741. Also, the resistence called LDR is actually a light-dependent resistor that can have a resistance from 0 to 5k.

simulate this circuit – Schematic created using CircuitLab

I have updated the resistances and capacity values, also i have added a capacitor in order to block the DC component of the signal. When i measure the voltage with the osciloscope at DC coupling in the Vout point what i read is a DC signal that moves from 0 to 20 mV with the shape expected of the hearthbeat. Now what i need to do is amplify the signal from that range to 2 V, but when i try to add an non-inversor amplifier OPAMP with gain of 10 (for example) my signal after the opamp dies. This is my first electronic proyect, i am trying to learn whit this so i will be very grateful for any help. Thanks.


texts: Finfet Device - Fin thickness vs Channel length

texts:
I dont understand why fin thickness has to be greater than channel length as stated below:

  As long as the fin thickness (body thickness), Tsi, is smaller than
  Lg, the short-channel effects are well suppressed and the subthreshold
  swing is basically the theoretical best case

Please help me explain why?
Thanks very much!


texts: We have a portable small toy which we want to make a sound on it when is connected to socket. I don't know if we must use a little speaker with a magnet or maybe we can make a noise with a mechanical object (like a beat on a very small bell). It must be as cheap and small as possible. Thank you and sorry for this noob question.


texts:
I have a doubt and I cannot find a certain answer on the internet.

All NPN transistors should work in the same way?, I mean, the only difference in all the models are just the rating currents and voltages?

My question is driven as I want to control the speed of a DC motor with an Arduino, and the suggestion is to use an NPN transistor, and on the example they use the BUF654, but on my country there's no model like that available.

So the BUF654 will work the same as a 2N5551 transistor?, the difference will just be the ratings?


texts: When do I need separate MLCC (input) and AL-ELEC (bulk) capacitors on my SMPS design?

texts:
I've been studying the specification of input capacitance for switching converters. I have a related question here that provides more background.

In my research into the topic I came across TI Application Note SLTA055 - Feb 2006 and an EE Times contributed article that both describe a similar approach to designing input capacitance for buck converters.

The gist is this:

You need two types of capacitors, input capacitors (large value MLCC) and bulk capacitors (AL-ELEC in most cases).
The input capacitors provide (much of the) current during each "on/conducting" period, reducing the input voltage ripple to roughly 75mV p-p. The bulk capacitors main role is to supply current during a load current step (until the supply inductance allows the supply current to catch up).
The reduction of input ripple voltage is important because otherwise the ripple current in the bulk capacitors is too high, and they heat up because of their higher ESR.

Now the capacitance in the MLCCs we're talking about here is not trivial, 84µF (implemented as 4x22µF) in the example they walked through.

This sounds like an awesome approach to me, and the math and everything seems to add up, but I find precious few high-value MLCCs in my scrap bin because it appears none of the designers of my choice e-Scrap follow this logic.

So my question is: "When would I need (or perhaps want) to use high-value MLCCs for separate input capacitance in an SMPS design?"

Responses to a related question I found on-site seem to indicate "Yeah it's a great idea but no one does it because it costs an extra buck". Or perhaps it was true in 2006 when these articles were written but electrolytic capacitor technology has improved since then? Another idea I had was that most of my power scrap is off-line, and maybe it's not needed or wouldn't work when the switched voltage is close to 200V? The one place I did find some high-value MLCCs is in an old Cisco router that seemed to have some point-of-load (POL) supply circuitry on it.


texts: How to assign the same value to multiple resistors in an LTSPICE circuit

texts:
I have around 10 resistors in a circuit, all with the default value "R".

I defined the directive

.param R=100

Upon running the simulation, I get the error message

  Can't find definition of model "R"

Is there a general way to assign a value to all Rs at once or do I have to do it by hand one by one?


texts: GND arriving to the wrong pin of this chip on my PCB

texts:
I had originally done a PCB for another chip. All pins I'm using (1, 2, 3, 17, 18, 19, 20) are fortunately correct for the ATtiny4313 I'm now using, except GND that arrives on pin #4 of my PCB ... instead of pin #10!

An option for my prototype PCB (I don't want to throw them away) would be to use a small wire between GND and pin #10.

Question: just for learning purposes, would you see another clever option that wouldn't require a wire?

Would something like doing digitalWrite(4, LOW); or analogWrite(4, 0); work and internally wire pin #4 to GND i.e. pin #10? Or wouldn't it work because the ATtiny won't boot first if no GND is connected?


texts: Connection between an IA input and a preamp's DC/DC converter

texts:
There is this circuit shown in Burr-Brown: Instrumentation Amplifier Handbook: High-Side Current Sensing (page 74) that has an IA (INA117) input tied to the COM (0V?) of a DC/DC converter (DCP011515DP). The DC/DC converter provides a stable supply to the pre-amp OPA277. I don't see how that converter has anything to do with INA117.
I understand the general idea of the OPA277 that is to gain up the 50mV shunt by 200V/V and to have a 10V maximum differential voltage going into INA117. But why is there this connection between INA117 and the DC/DC Converter's COM (indicated in yellow)?

The 150V polarity is drawn incorrectly and should be reversed


texts:
I'm using serial communication with Arduino and Matlab, and I need a way to reset Arduno from Matlab once a serial connection is made. I'm using Leonardo, and I understand that it uses a virtual serial interface unlike other boards. How can I achieve that?

Thanks


texts: Using synchronous input along with asynchronous input at the same time in a flip flop

texts:
For example let us consider an SR flip flop.
If the clear input is 0 (active low) and preset is 1 this will force the output to go to reset condition (Q=0 and Q'=1.) But if the clear=0 and Preset =1 in this state we give set=1, reset=0 and clock =1 then will both the output be 1 and 1?
If so then using the overriding input when clock =1 is a problem. How to deal with this problem?


texts: L6202 H-bridge keeps breaking when switching directions

texts:
I chose to use the L6202 H-bridge IC because it has built in dead time as well a thermal shutdown protection. However I've already broken multiple of these from what appears to be current spikes when switching motor directions.

During operation the DC motor will be powered with 48V, and draws around 200-400 mA when moving. Right now we are only giving it full speed either direction, no PWM.

I've set up the circuit as basic as I can following the datasheet reccomendations.

Vs: connected to 48V
SENSE: connected to ground
Bootstrapping capacitors: 47nF/50V
VREF: 10 nF capacitor to ground
IN1/IN2: 3.3V high / 0V low
EN: connected direct to 3.3V

I powered the motors with a power supply (24V, 1A current limit) for testing and it worked fine. The chip has a built in 40ns dead time which I thought should be more than enough considering the switching is happening on the scale of nanoseconds. However, I started adding a delay because I saw current spikes on the power supply exceeding 1A (power supply was entering constant current mode). That made me realize the 40ns dead time was probably not enough. I added a 50ms delay between one direction and the other. When we tried running the motors in operation with 48V power supply (unsure of the current limit), a 500ms delay between switching directions worked, but with a 250 ms delay, the chip was destroyed.

I also thought maybe we needed to add freewheeling diodes to help current flow when we make sudden changes to the motor speed, but it seems to me that this is already built into the chip as part of the MOSFET structure.

When the chip is destroyed it appears to short the two outputs, Vs and gronud all together which is very strange considering that the chip has built in thermal protection that is supposed to shut it down at 150C junction temperature. When the chip is cooled down again Vs and ground are still shorted together along with the outputs and the chip is no longer usable.

Am I doing something wrong and/or is there a way to mitigate this problem and continue using this chip? 250 ms seems like a ridiculously long time to wait for a motor to switch direction.


texts: Calculation Inductance Voltage in book 'Practical Electronics for Inventors'

texts:
I'm curious is calculation in screen right?

Source: Practical Electronics for Inventors, 4th edition, page 139
I assume Voltage from 2-3 sec must be -0.2V, because dI/dt=(-1)-1=-2A, not -1A.
Am I right?


texts: Negative Freqs from FFT in Laplace Circuit Analysis

texts:
Do I use the absolute-value of the FFT frequencies when using the Laplace equations for calculating the impedance of an RLC circuit?
I'm currently working on something where I need to numerically analyze the steady-state response of an RLC circuit. I'm starting with an almost-square wave (i.e. the output me arbitrary waveform generator can achieve plus the frequency response of the amplifier) which I then converted to the frequency domain with scipy's FFT.
I then use numpy.fft.fftfreq to get the frequencies of that FFT result, so at this point I have the frequencies and their corresponding powers. (Note that I'm not doing any normalization yet because the absolute amplitudes here don't matter much and the only thing I'm going to do later is pass it through an IFFT to get the time-domain signal).
So then comes the RLC circuit. I'm using the Laplace equations (R, sL, 1/sC) to calculate the impedance.
And now I have an issue which I can't seem to find a reference to online: when I calculate those, do I use the absolute value of the frequency array? Or do I use the negative frequencies? Or do I trim out all the negative frequencies?
Obviously, if I use the negative frequencies, resonance becomes... tricky, to put it mildly.


texts: Did the Multicore Association went out of business?

texts:
I am working on a project with the ADSP-SC58x from Analog Devices which uses Multicore Communications API (MCAPI). As I am trying to gain more information about the API and standardization itself I recognized that the website from the Multicore Association (https://www.multicore-association.org) is down. Does anyone have an idea if they went out of business?

I tried to obtain some files and documentation with the waybackmachine (https://archive.org/web/web.php) but that did not work out.


texts: Is it necessary to cut off PV from grid before measuring its power output?

texts:
I need data of Power output from PV in one day.

I was told to cut off the connection from PV to the grid also because the measurement is from the inverter, I also need to change the phase into 1 phase before measuring it.

I am not sure I understand the reasons for these? Because the system already have monitoring system that could display the ouput data from the PV. Will connection to the grid affect power otput from PV that much?


texts: What is benefit of diode in the RC circuit

texts:
This picture for reset circuit of the 8284A clock generator can you tell me what is the benefit of diode in the circuit?

Second question why has the resistor been added between crystal an ground?


texts: Testing a 3-phase ev charger on an 1-3 frequency regulator

texts:
Im currently working in an office environment developing a system to communicate over rs485 Modbus with an 3 phase EV charger. Due to the location it is not possible to get three phase power. However I won't be charging cars and will be using a tester(mostly to simulate car type, charge times etc) is it possible/save to hook up an 1-3 phase 1.5kW frequency regular to do this kind of testing?
Thanks in advanced


texts: Trying to understand why the constant of integration was ignored on this RC circuit

texts:
I am watching this video where the guy deducts the voltage across the capacitor during the transient phase.

There is an integral, in the middle of the equations. The guy integrates that and there is no constant of integration after that.

This is not just this guy, I am not aware of any of the capacitor/inductor formulas where the tutor considers them.

Why is that? Why can you simply ignore the constant of integration for all these equations?


texts: Edge betweenness centralities for distribution grids

texts: Graph centralities like edge betweenness centralities are commonly used to study the vulnerability in transmission networks, can they equally be used to study radial distribution networks ?


texts: Simulating a Read/Write operation by FPGA in EEPROM

texts:
I have to write some data into an SPI EEPROM by the FPGA. FPGA will act as master, and EEPROM will act as a slave.  The problem is as I do not have FPGA board as of now, I will be simulating these read write operations.

I am able to do some master side simulation, meaning I am able to see the commands going(MOSI), and clock etc, but on MISO how do I get data, as there is no slave simulation.

My question is how do I simulate the behavior of EEPROM, so that when I start simulation I will also get response from the EEPROM (in simulation).

My idea is I will put some known data in simulated EEPROM, and when the simulation starts I get data on MOSI and MISO both, and thus I can verfiy the working of read/write operations.

I am using Lattice FPGA and SPI EEPROM from Microchip.


texts: Is there a certain type of LDR that will be most effective in a circuit that senses the heartbeat at a fingertip?

texts: I haven't had much experience with LDRs, and was not sure of the different types that will work best in a circuit like that.


texts: Parameter is incorrect error with usb 2.0 but not with usb 3.0 with C# serial program

texts:
I've been struggling to understand an error that is happening. I've got a simple program that sends/receives bytes over serial, and up until yesterday I figured was working 100%.

Basically, the issue is that my program works perfectly with any USB 3.0 ports, but fails on all USB 2.0 ports. I am only using Windows, and tested on both versions 7 and 10. The software is written in C#, and the AVR side is an Arduino, using an adapter with a large 512Mbit Flash memory on it.

I found an issue once I tried it on my spare laptop, which doesn't have any USB 3.0 options, and as soon as the program tries to send the serial data to my external AVR it crashes with a "The parameter is incorrect" error. Googling that error brings up a few hundred thousand results, all with completely different issues, so that error is super generic.

I'm using Dtrenable and Rtsenable, as suggested in other posts. My baud rate is a standard 9600. Here's how I'm initializing it.

private void Init(string portName)
    {
        myport = new SerialPort(portName);
        myport.BaudRate = 9600;
        myport.Parity = Parity.None;
        myport.DataBits = 8;
        myport.StopBits = StopBits.One;
        myport.Handshake = Handshake.None;
    }

Portname is set in a different section where I pull the available COM ports, and Dtr / Rts are being enabled right before I open the port to send the data.

Again, this works flawlessly on USB 3.0 ports on any computer I've tested, but fails on every USB 2.0 port. I should note that the AVR device is being powered by the USB port, but draws less than 100ma.

Any help understanding this would be great, thanks!

EDIT: Just checked something, and it only seems to fail if the file size being transferred is over 4MBytes. Any file smaller than that seems to write fine, even on USB 2.0. Anything larger than that fails on USB 2.0, but works fine on 3.0 ports.


texts: Is it better to have a higher Vgs than Vds on a MOSFET (n-channel)?

texts:
I've been studying MOSFET switching applications recently, and have been playing with the Circuit Simulator Applet here. In my diagram below, I have Vds usually set to either 12 or 14, as I am trying to design a decent buck converter for automotive applications, in which a constant DC output that has minimal oscillations is necessary.

I've noticed that using a Vgs of 12V, while also have Vds being 12V, results in a lot of heat being dissipated over my MOSFET. I've attempted to minimize switching losses by playing with the timing and inductance values, but have hit a wall.

However, I noticed that upon increasing Vgs higher than Vds, I minimize my switching losses almost entirely, if Vgs is set high enough. In this case, I have it set to 18V, which I cannot really hope to achieve in my application without some kind of voltage doubler/charge pump, of which I have not yet played with.

I'm wanting to make sure the behavior I am seeing here is consistent with reality and not just something happening in the simulator. Is it better to have Vgs higher than Vds? If so, am I wrong in my understanding that MOSFETs are designed to be low-voltage triggered switches, designed to control high voltage, high current loads?

My circuit can be found here that I have set up. Along with some of the sliders I was playing with to try to make it efficient. To anyone that knows whether this is true or not, please explain as much as you can! Very interested in this subject.


texts:
For 3 input XOR gate and XNOR gate, by solving the equations I got the result as in the picture.

So according to the solution the outputs of the 3 input XOR and XNOR gates are same. This solution holds good when number of inputs to the gates are odd.

For the case of even number of inputs XOR and XNOR are complement to each other.

With this assumption the answer to the circuit in the picture should be option A,B, and C. but the correct answer is D. I am confused as to how?

Thanks in advance for the help.


texts: Hi, while I am tring to repair electronic circuit. I'm encountering this sponge. I wonder what is this sponge? and can I find out what it is used for. I often see this in sensitive circuits like in laptop board and near to cooling parts. Adheres on cooler materials


texts: Processor with hardware camera interface port?

texts:
I was looking for a processor to interface to the DVP port of a 5MP CMOS camera module.

I could possibly write the software for doing this but I've heard that many processors have a hardware camera interface port that makes the job much efficient.

What would like to do is capture frames from  this camera and store it in external ram for some processing later.

Any idea how could I get around doing this? I just a small enough processor about 44pins or 64pins or so that has a camera interface port and external memory interface.

Edit: I think a small enough processor isn't going to be available, I'd be lucky if someone finds some most of the processor pointed out in the answers have 200+ pins. So feel free to point to processors without the "pins" limitation.


texts:
I want to make an ultimate powerbank for my biking trips. This involves accepting a dynamo input and slow charging the battery pack with its ~3W and also cramming as much energy as possible as fast as possible in case when wall power is available.

Is there an easy way to make the USB input be a well behaved device that supports QuickCharge? I'm hoping for something along the lines of TPS2514 (that's what I'm planning to use for output) where I would somehow choose maximal allowed voltage and then ask the chip to give me everything the source has. No data transfer is necessary for my device.


texts: Improve switching speed for a <50mW laser with an Arduino and Transistor

texts:
I'm trying to build a "laser harp" device similar to this: (http://www.instructables.com/id/Frameless-Laser-Harp/), but I'm having trouble switching my laser on and off fast enough, and for full disclosure, I'm very comfortable with software, but this is my first experience with circuits and hardware.

Basically, I have a <50mW green laser bought off Amazon for under $20, so, yes, it's not the greatest laser in the world. It draws 300mA at 5V.

My 2N2222 transistor's collector is connected directly to a 5V source, the emitter is connected to ground, and the base is connected to a digital pin on my Arduino.

I can successfully turn the laser on and off from code, but if the digital pin is on for less than 100 milliseconds, the laser loses brightness quickly. I have to have the digital pin on for at least 60 milliseconds to get the laser to light up at all.

I can switch an LED on and off very quickly, so I know my transistor can switch fast enough, but my guess is that the laser needs a certain amount of current before lighting and that it takes a while for the transistor to get to that point.

My question is this:

Using a 2N2222 transistor and this 300mA laser diode, is there a way to switch it on and off with 1ms resolution? Do I need different components to make this happen?

EDIT:

This is the closest I can get to a datasheet for this laser... from amazon:

Dimensions: φ12x51mm( with PCB circuit size)
Output Wavelength: 532nm (+-10nm)
Output Power :<50mW
Laser Shape: Dot
Beam Divergency: <1.5mard
Shell material: Brass
Circuit Control: ACC line
Reverse Polarity Protection: Yes
Working Voltage: DC = 3.7V
Working Current: I <250mA
Warm-up time: None
Operating temperature: 0 C ~ +40 C
Storage temperature: -10 C ~ +55 C


texts: Protection Against High/Negative Voltage for Arduino

texts:
I am currently on a student project where I have to create a portable device that allows the output of sensors connected to it to be displayed on a 16x2 LCD screen using an Arduino Uno R3.

One of the important requirements is that, while the majority of the sensors that will be connected have an output range of 0-5V which the I/O pins of the Arduino can handle, some sensors can have an output range of 0-16V. So it is important that the device has the appropriate protection against over voltage/negative voltage as well as any signal conditioning required for values outside the 0-5V range.

What I've decided so far is to use a voltage divider to lower the maximum value of 16v to 5v and to use a zener clamping circuit to to keep the input to the Arduino pin between 0-5V as well as including a buffer amplifier to ensure the output voltage only changes according to the sensor.

Here is a schematic of what I am planning to do:

Will this method work, what do I need to do to solve this problem?

Thank you very much for reading!


texts: My push-pull converter uses a flyback transformer with an air gap. How does changing air gap size affect the secondary output voltage?

texts: My push-pull converter circuit uses a flyback transformer with an air gap.  If that air gap is changed (increased), the primary inductance is decreased.  How should I expect the secondary voltage and the output waveform to change after increasing the flyback air gap?


texts: Why different SOCs have different CPU power voltages for given frequency?

texts:
Recently, I studied dvfs tables for 3 SOCs: exynos8890(LITTLE cluster), exynos7880, snapdragon 625.

Here is the result:
octave source code

The point is, that different SOCs with pretty same manufacturing process (14nm), same CPU architecture (arm53), but different manufactures, and consumer grade have different voltage at given frequency.

It's clear, that reducing CPU power voltage, one can reduce dynamic consumption, but still,
Does reducing CPU power voltage has any drawbacks on overall CPU power consumption?
Also, why exynos8890 has peak voltage at 1.6GHz, but not at MAX frequency?


texts: I have a motor that constantly rotates in reverse, the current is measured at 5-8A, and the selenium rectifier (Fwd: 1.2A Rev: 150V) is used.But it didn't take long to burn, what should I replace it with?


texts: RMS vs DC(mean value) when calculating power of pulsed or rectified signals

texts:
When I have either a rectified signal (like the unfiltered rectified sine wave out of a diode bridge) or say a fast pulsed signal feeding a LED and resistor, in which both the DC component and the RMS component are high, which value RMS or DC should I use to make my calculations?

In some cases Ive read books which use the DC (mean) values to analyze voltage or current values, yet they use the RMS value to calculate power, and in other cases they use the mean (DC) values of voltage and current to calculate power.

Im confused as to when should I use DC values for current, voltage and power and when should I use RMS when both are present and with great magnitude. I understand the definitions of both RMS and Average and their integral formulas, in which RMS is the mean squared and produces the same "heat" as a DC signal with the same value. The problem is not the definition, the problem is when to apply RMS values or DC values when I have both present in a signal.

Let me give you an example to clarify my question, say Im pulsing an LED in series with a resistor with a fast signal (0 to 5v pulse, 20% duty cycle). The RMS voltage and current values of the LED may be 1.5V and 6mA, and the DC voltage and current say 1.7V and 4.5mA, which should I consider the voltage and current of each LED: 1.5V and 6mA, or 1.7V and 4.5mA?, what about if I want to calculate the power dissipated on both the LED and the resistor, should I use the RMS voltage and current values or the DC values?


texts: 3 different regulators at the output of an SMPS

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Hello: I'm a beginner in electronics, so I don't know if my question is a stupid question. I have a chinese commercial SMPS rated at 24VDC 15Amp 360W output and I need to get from this output 3 differents outputs at 5V, 16V and 20V, this last one with 4Amps max. spike loads. (It`s a motor drived by a L298 board and some latching CMOS logic controlled with tact switches.

It Is possible to use 3 different regulators 78XX, one 7805, one 7815 and one 7820 connected to the 24V Output of this SMPS to get this three different voltages?

Consumption of the 16V output will be about 20-30W for some LEDS and relays and the 5V output is used only for sending the H TTl levels to 6 cmos chips and a few 3V leds.


texts: Practice for complex electronic circuits

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I'm self-learning electronics; I've watched Anant Agarwal videos and read his book and another book "Electronic Devices And Circuit Theory- Robert L. Boylestad".

But, now, I need to practice more on building complex circuits like those involving multiple transistors or more than, say, 10 components.[please don't tell me that's not complex because it's still complex for me.]

so, where do I begin? are there online video courses or books for that purpose? What's your recommendation

and one more question, where do I begin for PIC microcontrollers?


texts: linear-control 12V DC fan with 5V low-current (Arduino)

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I am trying to control a 12V DC computer fan ...

without PWM for longer life and less high-frequency sound emitting
Controlled by 5V positive voltage coming from the arduino after a DAC

Using a low-pass filter I can turn the Arduino's 5V PWM @290Hz to a linear and smooth voltage:

My question: How can I control the 12V fan now, while

0Varduino = 0Vfan and
5Varduino = 12Vfan ?

A MOSFET is saturated really fast and would close the fan circuit instantly at 12V
Thank you in advance!


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I am trying to make a IR sensor but somehow its not working.Below is my circuit diagram

when i bring my hand  near the sensor, the led connected to pin1 of lm358N does not glow.
I also checked the voltage at pin2 of LM358N ,it is reading 5v whereas pin3 reads 3.2 v.
when i bring my hand near the IR sensor, the voltage remains same.

I actually tested my circuit using tv remote and found that my IR recevier is working fine so may be transmitter have the problem .so i took my cell phone any saw the transmitter using my cell phone camera but couldn't see anything .I have changed my transmitter but still i cant see radiation in my camera .whereas my tv remote transmitter radiation was visible.what could be the problem?