texts: How to place a 7805 voltage regulator on a breadboard?

texts: I have this breadboard and I have started experimenting with pic micros.  In doing so I have needed a 5 volt power supply.  I have seen several tutorials for wiring up 5 volt regulator circuits on a breadboard, however when I try to hook up the 7805 on the breadboard, the 7805 will not fit on the breadboard.  With extra force I can force it on the breadboard, but I assumed this would damage the breadboard.  What is a common solution to this problem?


texts: Importance of Sine Waves And Maxwell's Equations

texts:
Sine waves, by a huge margin, are the most important waveform in electronics - we measure a circuit's frequency response with sine waves and represent all other signals through sine waves, with the help of the Fourier transform. However, Fourier transform on itself does not make sine waves special - after all, there are other ways to decompose a signal into a bunch of orthogonal functions (wavelet transform, for instance).
So there must be a fundamental physical reason for sine waves being so important. I would imagine that this reason is the fact that the electromagnetic wave equation (which can be readily derived from Maxwell's equations) is a second-order diff eq, so a sinusoid is its solution - that's why sine waves do not disperse in transmission lines and that's why a "frequency component" that has a particular propagation velocity in a medium, is a sinusoid.
Is the reasoning above correct? In a fantastical world where the equation of electric signal propagation was, for example, a third-order diff eq, would sine waves be as important as in our reality (I know it's a bit ridiculous to ask what would happen if the fundamental physical laws were different, but still)?


texts: Correct order for electronic ballast and circuit breaker

texts:
I´m setting up a circuit which involves a light, an electronic ballast and a circuit breaker in order to protect the whole connection (Very usual power failures).

Is the circuit breaker recommendable?
If so, which is the correct order for the set up?

Thanks.


texts: Choose the right battery for a given electrical equipment

texts:
I have an electrical equipment which is connected to the power supply via an adapter which specifications are:

INPUT: 100-240Vac, 50-60Hz
DC OUTPUT: 24V, 3.125A (75W max)

I would like to use a battery instead.

I have found a battery which specifications are:

26400mAh capacity.
Maximum Output: 24V Port: 2.5A; USB Port 2.1A

I don't really know how to read this spec. (especially the "Port: 2.5A" part).

My questions are:

Do you think that the battery is compatible with the equipment?
What parameters should I consider to select the appropriate battery for a given equipment?
What parameters shall I consider to prevent the equipment from being damaged?
What are the important parameters on the equipment side? Voltage + Intensity + ???
What are the important parameters on the battery side? Capacity + Voltage + ???

These questions may be a bit redundant: it's because I'm not sure what the right question is...

Thank you for your help and best regards.

============================================

This would be the equipment (this is a printer, see the paragraph "electrical specifications"):

https://www.zebra.com/content/dam/zebra_new_ia/en-us/solutions-verticals/product/Printers/Desktop%20Printers/ZD420%20Desktop%20Printers/documents/zd420-technical-specifications-en-us.pdf

This would be the battery:

http://www.bixpower.com/Bat-MP100-24V-p/bat-mp100-24v.htm


texts: What is the difference in working of an GMR readhead vs an EMR one?

texts:
As I understand it, a GMR readhead works by stacking magnetic and non magnetic layers, passing a current through them and measuring the total resistance. Then a 4 point measurement is used to remove the effects of the borders, like so:

Now, the schematics of an EMR shows the following:

I'm assuming that the Au resistor is just normal shunt register that is used to measure the total resistance. So I'm assuming that this is not the stack below and what are looking at is only the connection from the 4 pins upwards (which was circuitry in the above figure). So the 4 pins there are the pins as above. Is this correct?

If so, then how can the EMR diagram shown above possibly provide the same functionality as an GMR when the SiN and InSb are insulators and the I- en I+ pins can't even be connected to a source?

If not, then it should be the other way around; the circuitry remains the same, but the stack is replaced by the insulators and the shunt resistors. This doesn't make sense to me as the whole reading mechanism of the stack is now nowhere to be found.


texts: Is Hand Soldering a DFN Package Possible?

texts: Is it possible to hand solder a DFN package? It's leadless, so it could be tricky. I can't find any videos on YouTube about it, so I'm sort of thinking it as difficult, if not impossible.


texts:
I have a question about the standard 555 circuit below. I understand to some degree the "insides" of the timer. In particular, I understand the role the comparators play and I am fairly certain I am able to follow the logic as the voltage going into pins 2 and 6 increases.
My main difficulty comes in understanding why the same voltage (+5V say) charging the capacitor isn't also going into pins 2 and 6. As it has been explained to me "the capacitor voltage is what is fed into the comparators," however this seems counterintuitive as in my mind there should be a Vcc voltage (+5V) fed into the comparators as well as the capacitor, and it seems to me that this voltage would drive the logic.
The explanation I've been able to convince myself of is that "Vcc is providing only as much voltage to the capacitor as the capacitor currently has" -- this however seems to not be in line with the explanation as there seems to be an implication that the capacitor is what is flowing into pins 2 and 6 and not the voltage straight from Vcc. If this is the correct explanation, then it appears I am missing some key intuition for the workings of voltage in such circuits and would greatly appreciate an explanation/reference.
My understanding of electronics is very basic, so I expect I'm missing something easy, or more fundamental.


texts: Motor will only run properly with a meter inline, will only pulse without

texts:
I have a DC 12V 550 motor that will not run properly while on a power supply.  It will only pulse and not consistently run.  I figured my power supply wasn't supplying enough current.  It's a 12V 8A power supply, so I hooked up my meter to it inline to read the current draw, and wouldn't you know it ran perfectly.
To further complicate things, it will also run perfectly if wired directly to the motor from the power supply, but not through a 5.5mm jack.
If I use a 10A power supply, it runs ok through the jack just fine without the meter inline.  I have tried various 5.5 barrel jacks and all have the same result.  These jacks are rated at 10A DC so why will it run with the meter inline, and only pulse without?
I have a few of these to build and I have a drawer full of 8A power supplies that I would rather use than spend the bucks on all new 10A units.


texts: What situation would you use flexible termination ceramic capacitors?

texts:
These capacitors from Kemet have flexible termination.

The datasheet says it caters for applications where the board flexes and normal ceramic caps can fail. However, I fail to see a situation where PCB's flex? If PCB's had the potential to flex, wouldn't you just get a tougher enclosure?


texts: Why don't electrons from conduction band jump to the acceptor level?

texts: One basic idea of Band theory is that electrons always try to occupy the lower energy states. Acceptor levels have vacant low energy states . Then why do electrons from Conduction band don't fall back into acceptor levels? Why always valance band electrons go to acceptor levels giving holes?


texts: Do I need to buy USB Blaster with DE0-Nano?

texts:
I am moving this question here to separate question altogether:

  [DE0-Nano] [l]ooks really good, but do I need to buy the USB Blaster (or another
  programmer) too?

Please, explain the context in a beginner style, what is it really needed for?

Related things

http://www.terasic.com.tw/cgi-bin/page/archive.pl?Language=English&No=46#section (USB Blaster clone)
http://www.terasic.com.tw/cgi-bin/page/archive.pl?No=593 (DE0-Nano board)


texts: I've seen the term "tone" used a lot in RF literature, but haven't found any helpful explanation of what exactly a tone is. I am looking at tone in context of IMD; i.e. the fundamental input tones. What exactly is a "tone" in this context?


texts: How to properly voltage divide an AC/differential signals

texts:
What is the proper resistor configuration for voltage dividing an AC or differential source?

For simplicity sake assume i would want to reduce a  5v pk-pk perfect sine wave to half 2.5v pk-pk @ 5kHz. The voltage divider is to be read by a differential ADC. Note that resistor values to get the desired output in the image might be wrong since im not sure how to balance as its not the typical voltage divider anymore (B and C)
I have seen all this circuits and it would seem they all do the job (using simulations) but i would like to know which one is best for what,
what if the signal is not perfect for example like a lets say a microphone where the frequency can vary and voltages too. (assuming again the ADC has a sampling frequency way above the required)


texts:
I have one question about the following products:
foca-v2-2-ft232rl-tiny-breakout-usb-to-serial-uart
sparkfun-ftdi-basic-breakout-3-3v

I bought them last year and after time without using them I tried theses days. They seemed to be broken somehow so I researched and found this link:
ftdi-drivers-break-fake-chips-again

This is the problem I face. My FTDI breakouts are now completely worthless because of a windows update.

Any idea how to make them work?

I am using Windows 10, so disabling the windows updates is not a "valid" option. It can only be done by sh****-tricky registry modifications for the network.


texts: Understanding Rp / Rd switch in USB-C DRP/DRD 2.0

texts:
There's this Rp/Rd switch schematic mentioned in TI's primer on USB-C that I don't quite understand.  The original text on page 6 goes:

A DRP/DRD can present itself as either a UFP or DFP. As a result, this
design must have a method to pull the CC lines up with Rp or pull the
lines down with Rd (default on a dead battery in order to charge), as
shown in Figure 6. Notice how the switch can toggle between pulling
the CC line up (in this case, with a current source to create a
specific voltage across Rd), or pulling the CC line down to GND.

AFAIK a DFP pulls CC1 and CC2 pin high with pull-up resistor Rp, and a UFP pulls CC2 and CC1 low with pull-down resistor Rd.  The two resistors, Rp and Rd, form a voltage divider and controller on either side of DFP or UFP can sense a specific voltages values and regulate the Vbus voltage or current.  So a DRP/DPD device should be able to switch in between being pulled up by Rp, or pulled down to ground by Rd.

But the only resistors shown in the schematic are two Rd resistors pulling both CC1 and CC2 down to ground (UFP). If the device is switched to DFP, there are no pull-up resistors, but instead CC1 and CC2 are driven by an unspecified current source. What does the current source do? Where are the pull-up resistors Rp, and where is the voltage source Vbus that Rp should be pulling up to?

I don't get where it says "... a current source to create a specific voltage across Rd ...".  When CC1 or CC2 is pulled up to the current source, Rd will become an open circuit tied to ground - how could there be any voltage across Rd?


texts: RLC circuit - transfer function through differential equation - Band stop filter

texts:
Need to find the transfer function of this band rejection filter via its differential equation but cannot figure it out since it was some time ago I studied electrical circuits.

I know that I should use Kirchoff´s laws as well as the differential equations for the different components:
Inductor:
$$ V=L \frac{di}{dt}$$
Capacitor:
$$ V = \frac{1}{C}\int i  dt$$
But I´m not sure in how to move on. Any help on this matter is would be much appreciated.
Another way to get hold of the transfer function would be by going via the circuits impedance, which I thought I knew how to do but after simulating my TF´s Bodeplot in MATLAB with the same in LTSpice I must be doing something wrong.
First of all, the parallel combination should result in:
$$ Z_{tot}=\frac{Z_C Z_L}{Z_C+Z_L}=\frac{\frac{L}{C}}{\frac{1}{jwC}+jwL}=\frac{jwL}{1+j^2w^2 CL}=\frac{sL}{1+s^2CL} $$
As usual: $$Z_C=\frac{1}{jwC}, Z_L=jwL, Z_R=R$$
And the voltage divider should give:
$$ H=\frac{V_O}{V_I}=\frac{Z_2}{Z_1+Z_2}=\frac{Z_2}{Z_{tot}+Z_2} = \frac{Z_R}{\frac{sL}{1+s^2CL}+Z_R} \frac{R}{\frac{sL}{1+s^2CL}+R} = \frac{R(1+s^2CL)}{sL+R(1+s^2CL)} $$
And breaking out RCL I get:
$$ \frac{RCL(s^2+\frac{1}{CL})}{RCL(s^2+\frac{s}{RC}+\frac{1}{CL})} = \frac{s^2+\frac{1}{CL}}{s^2+\frac{s}{RC}+\frac{1}{CL}}$$
But after making a Bode of this in MATLAB with the values C=20nF, L=50mH and R=5k I do not get the same cut-off frequency in both softwares. What is it I´m doing wrong?


texts:
I was wondering about the industry standard for building cabling of Cat5e from the elctrical closet to the end user.  More specificly from the patch panel to the wall plate.

I was told at some point that the ends on your link from the patch panel to the wall plate should be of the same type. I.E. 110 punch down socket of brand X going to another 110 punch down socket of the same brand X and not to exceed a 280 foot cable length.  This way you have a nice neat cabling job, and any patch cables you use shouldn't exceed 10 foot in length so you'll never go over your 300 foot limit.

I was working at a place that didn't want to follow that method all the time.  They instead would run a cable (less than 280ft) from the 110 punch down patch panel to the user but would instead pull the cable out of the wall through the wall plate and terminate with a RJ45 plug.

Aside from it looking cheesy, what are other problems you could encounter from this type of cable run?  I was thinking that you might have impedence mismatches going from brand X 110 punch down socket to a brand Y plug that could possibly increase errors on longer runs?  You would also have possible cable failures as the patch to wallplate cable typically would be solid core and be more prone to breakage from all the movement at the wall/user transition.

Am I just being paranoid about this or am I correct about my misgivings?


texts:
I'm looking for a way to drive a MOSFET with discrete components.
Actually I need to drive a bunch of MOSFETs, with currents of 100-150A.
And I'm wondering it would be possible not to use driving ICs, to have more control over functionality, less complexity, less cost.

I've experimented with different arrangements, with resistors and capacitors. I'm using an oscilloscope to monitor ringing, rise/fall times etc.

The problem is that as soon as I introduce resistors, rise/fall time becomes very high.

The input signal has a rise/fall time of only about ~8-10 ns.
Using the BJTs alone, the signal is easily duplicated at similar rise/fall times.
But once the gate capacitance is introduced, the rise/fall time becomes significantly higher, e.g. 300-2000 ns.

I've thus been experimenting with different methods to reduce the rise/fall time:

Method A: NPN+PNP (Voltage-follower? current sourcing from Vcc?)

I made the following circuit, not realizing that the gate voltage would never be more than the input signal voltage.

I need the gate voltage to be more than 10V to minimize Rdson.

simulate this circuit – Schematic created using CircuitLab

Method B: PNP+NPN

I've experimented with different resistors and capacitors:

simulate this circuit

But I found that:

The capacitor reduces rise ringing, but increases fall ringing and time => removed
All resistors except R2 and R3 had a detrimental impact on rise/fall characteristics => removed
Using potentiometers for R2 and R3, I found that the best resistance was R3=4k and R2=1.5k.
Rise time 490ns, fall time 255ns.

I'm a bit worried that the gate voltage isn't dropping low enough, e.g. seems to stay at around 400mV. Although ground seems to be read at 250mV, so maybe the breadboard is just crappy.
How low should the gate voltage be to prevent any heat build-up in when the signal is constant low (off)?

I'm wondering if there's anything else I can do to improve the performance?

Improved circuit:

simulate this circuit

Oscilloscope:

Note: apparently the input signal was inverted on the oscilloscope by setting. I'll update the screenshots later...

Also, I've included the base of the PNP in the following screenshots.  Is it supposed to look like this? It looks a bit funky.

It seems the problem is that the NPN stays switched on, thus preventing the gate from charging.


texts:
I have a part i imported from manufactuerers part list and has the following layout:

This is the layout pattern in it's datasheet:

I had set DRC rules to have a min via hole size of 0.3mm and this is why this error pops up.
Should i simply ignore this error? Is there a way such that i still get all other DRC errors but this one doesn't show up?
Or would you remove the min via size rule altogether?
The manufacturers I am considering for this PCB have the following on their website:


texts: Separate microphone signals through phantom power

texts:
I've seen many circuits of microphone amplifiers, and some of them have phantom power in them. But usually there is only one input, and if I were to design a mic preamp for two mics, and get the phantom power from the same power supply, how would I separate the signals?

In the picture above, signal from one mic can easily go to both amplifier circuits through the phantom power line. What kind of circuit would isolate the two mics, but still have the phantom power from the same supply? Or is there a need to design the phantom power somehow to give separate lines for each mic, and if so, how would this be achieved?


texts:
I started to learn some basic idea on circuit building last semester. I got some chance to build up some simple circuit to construct some cooling system (with fan and some other IC). I thought I understand the concept of voltage, current and power but when in practical application I think I still not fully understand them. For example, I am building a circuit to drive the computer fan of 20w. There is a label on the fan stating that it should be driven as 12V. I know that power is voltage*current, so if we need 20w and drive it with 12V, I think we need about 1.6A. I made the circuit and it works. But today I am reading some books for beginner in circuit construction, in one project, they said you only have to provide 20w to drive one specific model of fan. So does it mean we can choose different combination of voltage and current if only we have the power is 20w?

Yesterday, I was working something with the peltier pad for cooling some stuff. It is said in the manual that we need to provide 96w (need 20V and about 4.8A) to drive the peltier and it comes with a power supplier, which provides 20V and about 5A output. It works pretty good when I connect the peltier to the power supplier. But I am pretty curious why in the manual state the specific working voltage and current if it needs 96W. I tried to use a DC power supplier with variable voltage and current output. I tried to make the voltage 5V and make the current about 1.5A, the peltier cooler still works (though not as efficient as with the typical input). Then I try to make the voltage pretty higher and with very low current so that the power is still about 96W. It is still working pretty well. So it is confusing me why most devices need to label the suggested voltage and/or current as well as the input power? But for some other devices, they only states the input power and voltage, they different mentioned any thing about the current!


texts:
I have an arduino that has one of its inputs pulled high and 'listening' for when either of two push buttons are pressed by pulling it to ground.

I would like this signal to also be sent to a nearby raspberry pi on one of its GPIO pins, so that it's pulled high by default and when either of the push buttons are pressed it is also pulled to ground. As the rpi expects 3.3v I was wondering if a simple transistor would suffice here.

Would the above circuit work as expected? So when the transistor switches on it would pull the 3.3v away, leaving that input pin on the rpi reading 0 volts?

Lastly, if the circuit does make sense is the following calculation correct for the base resistor...

current at collector = V/R = 3.3 / 10000 = 0.00033 A
hfe = 35
current at base... Ib = Ic / hfe = 0.00033 / 35 = 0.000009428 A
R1 = V/I = (5 - 0.7) / 0.000009428 = 456000 Ohm


texts: Why does the measured back-emf decrease when R is shorted in this circuit?

texts:
In the following circuit I move an iron rod back and forth inside a solenoid (represented by Rsol and Lsol) and measure voltage fluctuations across the terminals. I do this under two scenarios: with and without R shorted.

In each scenario, I adjust DC source V1 so that the DC current through the coil is the same. So with R shorted the supply voltage is lower and with the R in the circuit the supply voltage is higher.

Note: Rs is output resistance of my voltage source and Rsol is DC resistance of the solenoid. R >> Rsol >> Rs.

With the scope measuring across the solenoid terminals, I see that the AC component of the voltage resulting from oscillating the rod in the coil is higher with R in the circuit. Why?

My (probably flawed) understanding of back-emf is that it effectively acts to raise or lower the voltage at the terminals of the inductor. The consequence of this is generally that a current results (if there's a path for it), but back-emf is principally a voltage is it not? Since I'm measuring right at the solenoid terminals and the back-emf (AC) can be distinguished from supply voltage (DC), I thought this represents a direct measurement of back-emf.

UPDATE:

I think maybe what I was missing is that the back emf manifests across Lsol alone, not Lsol and Rsol. With that, is the following relationship correct, where Vsolenoidterminals is the measured AC component (ignoring DC)?

$$V_{solenoidterminals} = V_{bemf} - I_{bemf}R_{sol} $$
$$= V_{bemf} -\frac{V_{bemf}R_{sol}}{R_{s} + R + R_{sol}} $$
$$= \frac{V_{bemf}\left ( R_{s} + R \right )}{R_{s}+R+R_{sol}}$$

...so for very large R, you're effectively measuring back emf directly while for R=0 you're measuring a fraction of it which depends on how much bigger Rsol is than Rs?


texts:
I am looking for a device I can plug into an old TV's SCART port, which will feed me remote control commands (like 'arrow-up', 'OK', 'menu', etc.) received over the SCART connector's AV.link (control bus) pin in a usable way.

By "in a usable way" I mean in a form that is usable by a computer, e.g. over a USB serial connection, or may even as key presses of a virtual USB keyboard; Anything that a common computer could process.

Now, I am not looking for any product purchase advice, but I don't know what to search for on the internet to dig up something like this.
If such a device does not exist, how would I best go about creating one? Using an Arduino, e.g.? A few pointers would be greatly appreciated.


texts:
I'm new to Embedded programming and I'm trying to understand how Interrupt handlers work in different contexts/scenarios. I just want to know how a interrupt handler would work in the following scenario.

We have a data stream coming from a RS232 interface that is processed by some microcontroller. An interrupt handler(of void type) has a read() function which reads the incoming data bytes. If a character is detected then the interrupt handler invokes a function called detectString() which returns TRUE if the string matches the reference string which is "ON". If detectString() returns boolean TRUE it invokes a function called LED_ON() which should turn on an LED for 1 minute. If it returns false it should turn off the LED. Lets say the microcontroller has a clock frequency of 20MHz and an addition operation taken 5 clock cycles.

My questions are as follows

How do we approach this problem with an FSM?
The RS232 interface keeps transmitting data even after the LED is turned on. So am I correct in assuming that the interrupt handler should work with a one thread and the functions that it invokes should work from a different threads?
How would a skeletal program implementing this FSM look like? (pseudocode might really  help to understand the backbone of the design)


texts: How can I use a Teensy for a CAN bus project?

texts:
I have to use CAN Bus in my project. I need to use the Arduino software and a Teensy but I don't know what parts I should buy or how to make it work.

I have chosen Teensy 3.2 With CAN-Bus Breakout Board:

CAN Bus Breakout

Does this product includes CAN Bus?

I don't know what list of parts I have to buy to make it work.

Do I connect Teensy via usb to pc and that's it? Or do I have to connect the Teensy to a CAN Bus?


texts: Adapter for two different FFCs? (4 conductors each, but different Cables)

texts:
I have two different Flexible Flat Cables, both feeding two different touch panel and LCD packages.  I bought a replacement panel that was not the exact same model (the original model is nowhere to be found online), but I can only assume it will work as the model numbers were the same up until the very last couple of digits...and at any rate, I have no datasheet on the device's original LCD, so I couldn't check, I'll just have to try.  Upon receiving the panel, however, the touch panel cable was...different.  The other cables were identical, however (at least physically).  The cables are pictures below.  the B cable is the original, and the A cable is the one that came with the replacement package.  I started reading all that I could find about FFCs and the more I read (including several questions here), the more I realized that I might should ask an expert on the topic since I can't seem to make heads or tails (for the most part) with the information that I found!

In a nutshell, I'd like to find (or build if it's not THAT much trouble) an adapter that will adapt the A cable's end to that of the B cable's end.  There are markings on both cables, but none that turned anything up on google.  Maybe they'll look familiar to someone here though.

A cable: AA1017-43 CTC.

B cable: A0674D

If somebody knows right off just from the picture where I can find an adapter, that would be fantastic, but more than likely, I'll need help identifying them (which apparently involves some measurements) and knowing where to look for the components that I'd need for the adapter...and of course if there's anything I'm not taking into consideration due to my lack of experience on this specific topic!

Thanks very much!


texts:
I hope you can help me!

I’m going to categorize this into A) B) C)

Recently just bought a NUBM08 Nichia Laser Array and need to know how to get this boy working!

A)

So for this Spec
Operating Voltage = Mid 34V & Max 38V
Operating Current = Mid 3.1A & Max 3.5A

So how exactly do I get this working!? If you haven’t already watched; Styropyro has done this, Titled 40W Laser Shotgun on YouTube. So clearly it is possible.

From our Values above the wiring configuration would equal:

Series = 4.25V in each LD and 3.1A in each LD
Parallel = 34V in each LD and 0.3875A in each LD

So from here I think its going to be a Series Configuration

What do I do next…

B)

Using an LM317 current Regulator Formula
Resistor Required (Ohms) = 1.25V / Nominal LED Current (3.1A) = 0.4 Ohms

However I read that LM317’s lose there Efficiency after 0.2A or .200mA and I know they don’t work over 1.5A, therefore 3.1A / 0.2A = 15.5 LM317. so 16 LM317 are needed to make this run as efficiently as possible.

16 LM317’s Will run in Parallel so that Amps are shared between them all hence the reason for 16 LM317’S. This would now equal 1.25V / 0.2A = 6.3A

C)

So now that’s all done and I hope you understand and follow with me. How do I select the portable Power supply!?

Remember I have a Voltage of 34V and 4.25V across each LD a 34V battery would be big and Amps also very high.

Do I need a Voltage regulator also?

I’m all very confused and really hope you guys can help me here.

Thanks,


texts:
I have a quadrature photoresistor from a printer.
I want to determine the pinout. I can't find a datasheet for it. The case only shows "80058 - 96315" and I don't know the pinout.
The two phototransistors should have common GND and VCC, and separate channels.
Which pin is which?
I think B is GND and D is VCC, so A and C should be the two channels for the quadrature, however I'm not sure about it.
I switched my multimeter to "diode test mode" and got these readings:

This is the photoresistor:

I need some help to label each pin.
I found this old post that has the same PCB as i have https://www.eevblog.com/forum/reviews/avago-optical-encoder-pinoutdatasheet/ but nothing...
And this but nothing again https://reprap.org/wiki/Optical_encoders_01
The encoder is an Avago 96315 but there is no information nor datasheets about this item...


texts: Device/circuit for high current, short pulse discharge?

texts:
I'm tasked with replacing a relay with a semiconductor switch in a high voltage, high current, short pulse duration application (all relative, I concede).  Basically I'm charging a capacitor up to ~1kV and dumping it through a low-impedance load.  The di/dt requirements are pretty gnarly: ~400A with a ~300ns pulse width.  Due to other constraints it has to be a high-side switch, too.

simulate this circuit – Schematic created using CircuitLab

I originally tried using a high-power SCR, but all viable devices I've found have a di/dt limit of 100~150A/us, whereas I'm in need of about 2500A/us.

simulate this circuit

My next plan of attack is using an IGBT with a gate-drive transformer, though I'll have to make sure to keep the leakage inductance low.

simulate this circuit

My question, though, is if anyone has another approach to consider?  The isolation is a bit of a PITA but that's the route I'll take if it's the most practical.

EDIT: we were using these voltage-controlled solidtrons which worked perfectly (in a 5-lead TO-247-ish package) but now this is no longer an option.


texts: Can the OpAmp be safely removed from the Twin-T notch filter?

texts:
This is a very typical (text-book) example of an active Twin-T notch filter with adjustable Q.

However, after having posted THIS question, one of the commenters pointed out that there is a design that completely leaves out the OpAmp (OA) indicated, as it doesn't seem to serve a clear function/purpose.

I'm currently working on a design involving a high-precision Instrument Amplifier (IA), that is chained through a bunch of filters. The first one being the 60 Hz notch filter shown above, which is then output to an active 100 Hz LPF. The LPF consist of a typical 2nd Order Sallen-Key LPF, followed by a passive 1st Order RC LPF.

All the designs I have seen, are basically using this text-book Twin-T design with 1 or 2 OA's, for output and low impedance feedback, respectively. But are all these designs just a copy-paste artifact of people not thinking by themselves or are there important reasons for having the (indicated) OA in the circuit?

I have simulated the above (original) circuit here:

and and then again the single OA solution here:

This design show a pretty good response of -30dB @ 61.4 Hz (slightly off from original) with -3dB at ~65.6 Hz when using an 11kΩ pot set at 381Ω. But the original design seem to have better accuracy for \$f_c\$.

Q: What are the effects of removing the OA from the circuit?
(What side effects will this have on i/o impedance and component value sensitivity etc? Other pros/cons?)


texts: Modify part in Altium by exploding (or other method)?

texts:
There is a design in which I must remove silkscreen from every part, and I would like to do this without having to create footprints for every part that needs to be modified since I have many footprints and orientations.

Is there a way to modify a single part?

I know I can explode parts by going to tools->convert->explode component into free primitives. But if I rejoin the compoents the part does not come back. Is there a way to rejoin the exploded components back in to the part after modifying it?


texts: How to configure GPIO pins as digital outputs on LTC6804?

texts: Can someone explain how to configure GPIOs as digital output pins on LTC6804. I have a MUX whose inputs are connected on GPIO2 - GPIO4 and the output is connected to GPIO1. My task is to control MUX inputs so I can read various voltages on the output but the problem is that I can't find in the datasheet how to configure those GPIOs as digital output pins.


texts:
I'm planning out hardware for a project and would like to drive at least 2 displays, each using the SPI interface.
What I dont understand is why there are dedicated pins for the CS line (at least on Raspberry PI and Arduino). the selector. As I understand, the SPI device only listens if that signal goes low. Wouldn't any GPIO Do?


texts: ULN2003/ULN2803 for Switching Application

texts:
I'm prototyping a board which will drive a control module. I'm not an electrical engineer by trade but I have tried to learn as much as I can.
The board is intended to interface with 8 logic lines, where each may be pulled high to 30V which comes from the control module. These 8 lines are normally grounded. Inside the control module the signal from each line is converted into a lower logic level.
My board works using a PIC12F615 with a 74HC164N, which then drives a ULN2803 (I'm using a ULN2003 now because it's what I have on hand).
I know I could just use a PIC16 with an array of transistors, but minimizing component count and board size is important. There will be a high volume and I will be assembling these myself.
With BC547 transistors in the open-collector configuration, and the emitter tied to each of the 8 logic lines, things work as expected. What I have essentially tried to do is replicate this using the ULN2003/2803. Both configurations sink current, right?
Here, my issue lies at the last stage, at the Darlington array. I am not sure if using this is compatible with my switching application, but I have been stubbornly trying to make it work.
The only configuration that has worked so far has been connecting all logic lines to board ground and 30V to the ULN2003 COM / all output pins - but this only works for one channel, otherwise it simply pulls every single line high with even just one input high. The lines must be individually controlled.
Treating this like a switch by adding a pull-down resistor did not work. The voltage drop is too great.
I've come to the point of concluding this just isn't possible. I'm not sure where to look next besides other transistor array ICs...
Am I correct in my assumption or have I missed something fundamental?
I'd really appreciate any feedback.
** R1-R8 are for the simulation to work only


texts: How can I replace this inductor with a transmission line?

texts:
I'm new in transmission line theory, hope you can help me. I have this circuit:

And I have the admittance; Yin=(1-j) x10^-3 [S] and its frequency f=100 [MHz].

What I need its first to find the values of L and C, so that the admittance of entry Yin  be the mentioned before. Then I need to replace the inductor L by transmission line in open circuit. The characteristic impedance is 50[ohm] and the phase velocity is 80% the speed of light.


texts: Is there an electronics reason why implantable RFID capsules are made of glass?

texts:
I am curious why implantable RFID capsules are made of glass because they create a huge risk of breaking under the skin causing some serious trouble.

I would guess a silver/titanium encasing will be better, and, if I'm not wrong, those metals are not magnetic, so I don't see them causing a problem with the electo-magnetic fields.

I'll put the same question on a medical stack exchange, and see maybe the reason is medical not electronics related.


texts:
I am going to use an MP1584 stepdown to convert 9v battery to 5v to power a STM32F411CE board.
And a second one to power two 6v n20 motors.
Learned that I always have to connect GND from all components.
But the MP1584 has specific IN and OUT GND connections.
Do I "just" connect IN and OUT ground of those mp1584's ?
mp1584 : https://www.aliexpress.com/item/32824806452.html?spm=a2g0s.9042311.0.0.36824c4dOvCbKN
motor : https://www.aliexpress.com/item/33016910240.html?spm=2114.13010708.0.0.3a994c4djAlU6W
STM32F411 : https://www.aliexpress.com/item/4001157813131.html?spm=a2g0s.9042311.0.0.36824c4dOvCbKN


texts: Building a small 3-axis accelerometer mote

texts:
I'd like to build a remote device which reports its current 3-axis acceleration to a nearby (<10m) receiver. It needs to be as light and as small as possible. (I have no preference as to the receiving end, but ultimately the data will need to be pulled into a computer in real-time)

Does anyone have any recommendations as to how to go about planning this build? At the moment I'm looking at a low power digital accelerometer from Sparkfun and their simplest transmitter and receiver boards, I haven't really considered how I'd wire these together yet - I've selected these products for their size and low power consumption (~8mA together) so I can keep the inevitable battery really small too - the 5V requirement of the Tx board is a bit annoying (a coin cell would be perfect at 3V).

Any thoughts welcome, a winning answer would be one linking to material that helps me plan the circuit for the transmission of the data from the device back to the receiver.

EDIT:: On the advice of the commenter below I'll detail my thoughts on data rate needs.

I'd like to be able to be able to transmit the 3-axis acceleration of the remote unit in as close to real-time as possible, with a sample rate at 100ms or faster (though I'm prepared to be flexible on this)

To be a little clearer about what I'm building here, I'm trying to capture the acceleration data from things like juggling balls/poi etc to turn into visualisations on a computer. Thus size really is critical (XBee modules would be a little big I believe) however accuracy as to acceleration is not completely vital


texts: What is the most accurate way to measure internal resistance of a consumer battery?

texts:
The typical way to measure the internal resistance of a battery, that I've found through research, is by connecting the battery in a circuit with a resistor, measuring voltage through the battery, calculate current, measure voltage through the resistor, find the voltage drop and use kirchoff laws to calculate the remaining resistance, which would be internal resistance.

A professor mentioned that this is too inaccurate for batteries with very low internal resistances, so is there another, more accurate way to test the internal resistance of a standard battery?


texts: How to connect to the PCB of an Alcatel Linkhub HH40

texts:
I recently bought an Alcatel Linkhub HH40 4G router. Unfortunately, the web interface doesn't provide the functionality I was hoping for (e.g., automatically disabling the radio functionality over night). Therefore I opened up the case to check if I can connect via USB, serial interface, etc to the operating system- but I cannot find a connector to connect to.

I attached the photos of the PCB. Can anybody help where/how I can connect to the operating system of the router (soldering is not an issue, if required).

Thanks!


texts: Using a micro-controller to drive an ignition coil

texts:
I am building an Arduino/Speeduino based ignition controller and want to drive a 12V coil from a digital output of the ATMEGA2560.

Below is my design for a coil driver using an IGBT (NGD8205ANT4G) with an isolated IGBT driver (UCC21520). I used the UCC21520 evaluation module schematic for component values.

Does this solution look like it would work?

Edit. Revised components and layout:


texts:
What happens when I have a low pass filter with R = 1kΩ C = 0.1 µF and I input a square signal with different frequencies? Will the time constant be the same for all frequencies?

τ = 100 µs for 1 kHz but when I increase the frequency τ starts to decrease on my oscilloscope. I thought τ was constant regardless of the frequency.


texts: I have a question about the datasheet for AD8330 VGA (variable gain amplifier)

texts:
I don't have much experience reading datasheets. I was reading the datasheet for AD8330 VGA. I did not understand what the difference is between VDBS and VMAG. Can someone elaborate on that?
It's mentioned throughout the datasheet. The below picture is from page one of the datasheet. Is the idea that we can choose whether we want dB gain or regular numeric gain? And if we want to control the value for VMAG, do we just connect it to vcc?

It's explained more on page 17 of the datasheet.

The datasheet is for the AD8330 VGA. You can access the datasheet from here: https://www.analog.com/media/en/technical-documentation/data-sheets/AD8330.pdf
Thank you


texts:
I'm designing an amplification stage using an MCP6021 op-amp operating from 0 to 5V. I managed to tune the circuit so I get 515.646mV to 4.878 V but I could get like 4.99V if tuned the gain a bit more. The reason for not doing so is because I was suggested to keep a minimum of 50mV from both 0V a 5V due to voltage range limitations of the ADC (I'm using a 10 bit ADC by the way), which would be 4.95V.
I've been researching about these "voltage range limitations" but the only limitation I found is resolution, 4.88mV ideally, which is ~10 times smaller than 50mV. Could someone explain what I'm missing? Thanks


texts: 110V AC/ 9V AC power adapter (America) Vs. 220V AC/ 9V AC power adapter (Europe)

texts:
Possible Duplicate:
  Choosing power supply, how to get the voltage and current ratings?

I have a device that I brought to Europe from America. It has a 110V AC/ 9V AC power adapter that stopped working. Over here I found a 220V AC/ 9V. I'd like to know if it'll work despite the 110V/220V difference since the device will receive the same 9V


texts: How do I get proportional 240V AC output from an Arduino-based PID controller to "dim" a rice cooker for a Sous-Vide project?

texts:
I'm making a PID controller for Sous-Vide, using an Arduino.

I'm trying to decide how to control the output. Using an SSR as an on-off switch on 240V AC will probably give me the result I'm looking for. However, I'd rather have a more continuous proportional output, so the rice cooker can be effectively "dimmed" rather than switched on and off.

What do I need to do this? Is a TRIAC essential? Will certain SSRs do this? Will all SSRs be capable of this? Do I need to build a 240V circuit from components myself, or are such devices available at similar costs to an SSR?

CLARIFICATION

I may have mislead with the word "proportional". I am building a PID with an Arduino. I will use it to drive a dumb rice cooker, and I'll have a temperature probe to detect temperature. This is the background to the question I'm asking.

I think it will be fairly easy to use a relay or SSR to turn the heater on or off every few seconds to control the heat appropriately. However, what I want is to be able to control the heating element so it runs at a fraction of full power, rather than turning on and off all the time. I would prefer this as it gives better temperature control, and I just prefer the idea of a constant electrical load as against switching 2000W or so every few seconds.

So I have a 5V digital output that I can control with a microcontroller (I believe I can control it far faster than 50Hz). I want to use this output to control the heat output of a heating element. I think the right device to use is a 240V SSR. My problem is deciding what sort of SSR I need, and then how to use it. I'd prefer a complete device with power plugs (like a powerswitch tail - http://www.powerswitchtail.com/ - but for 240V, and with the ability to dim rather than just switch on and off).


texts:
I am having trouble finding a good resource for understanding the design of a very basic AM modulator circuit.

Specifically, I am using a simulation tool which provides an AM wave, which consists signal frequency and a carrier frequency.  It produces a nice AM looking signal.

I am trying to create that signal from more basic components, but I cannot find any working schematics.

I am using a handy simulator found here: http://www.falstad.com/circuit/circuitjs.html

In my case, I am using a 40Hz signal on a 300Hz carrier. The AM element is configured the same way.

My 300Hz element is AC, -2.5V <-> 2.5V.  My 40Hz element has a base voltage, so it goes between 0 -> 5V.

I'm pretty sure I'm missing a lot, but can someone help me fill in the blanks?


texts: Suitable motor for steering wheel angle of the self-driving car?

texts:
I am working on the self-driving car as a final year project. I want to map the steering wheel motor angles with frames captured via a camera of the track. In order to generate the dataset, I am looking for a motor, whose angle can be read at any instant, so that I can create a database where each frame is mapped with its steering angle. After training, each frame will predict the steering angle and steering wheel motor has to turn accordingly.
That means a special kind of motor is required, whose angle could be read while training the car and also it could be turned at any angle via a microprocessor while testing the car.
I know that DC motor angle can neither be read (required during training) nor it can be turned at a specified angle via a microprocessor(required during testing). Encoder DC motor angle can be read at any instant but it can't be moved at a specified angle via a microprocessor. Stepper motor can be moved at any angle by a microprocessor but its angle can't be read, likewise for servo motor.
Please educate me if there is any lacking. I have on purpose explained the application where I want to use the motor, so that you may have better insights about which motor to use?


texts: Is Ground in a circuit nothing more than a return path?

texts:
So I work on motherboards and understand ground is both a reference point (acts as 0 when testing against) and its "where electrons carrying charge want to go." but why?

Since a battery separates electrons and protons to opposite ends (and please correct me if I'm wrong, no electronics background here), you have a build up of electrons carrying negative charge at one end (positive terminal for conventional). Those want to get to negative terminal where there's both a lack of electrons and build up of protons --basically to be balanced.

And since short circuits involve an unintended path to ground - example cap becoming wire to ground, is ground in a circuit nothing more than an easy return path to the other end of the battery terminal where electrons want to go?

Again I'm just asking about circuit ground not earth ground. Thank you for your help.

First thanks for all the answers I really appreciate it. So am I correct to state the following:

Voltage isn't a set number or "thing" but rather the difference between two points in a circuit? Example a battery really isn't a voltage source but an introduced abundance of electrons built up at one terminal while doubling as the object that completes the loop for electrons to "flow?" Since there's a lack of electrons at the opposite terminal they rush through the circuit to get back to this "lack of electrons" to become balanced.

Ground is a point, deemed by engineers, to measure all voltages against aka reference point. When designing they measure voltages against the same point and list those in the schematic. So ground isn't really 0 it's just acting as our 0 reference point to measure another point against?

And by return path do you mean the other battery's terminal is connected and allows electrons to flow back through it? Thanks again.


texts:
For this marchand balun schematics in ADS, how to instruct the ADS layout generator to use coil shape (for area saving in IC) ?

Besides, anyone have any experience with planar layout of marchand balun on PCB ?

balun schematics

generated balun layout not in coil shape

balun layout in coil shape


texts: Can Network Analyzer measure Impedance, Conductance, Susceptance or is there a device that does all?

texts: I want to measure the impedance, conductance and susceptance of a large metallic object (about the size of a boat), and I want to know if it is possible to measure using Network Analyzer. If yes, are there steps that I can follow to measure the impedance, conductance and susceptance.


texts: Effective area or effective aperture of antenna

texts:
The effective area simply represents how much power is captured from the plane wave and delivered by the antenna. The explanation begins oft with assumption that antennas have the same polarization.

  A plane wave with the same polarization as the receive antenna is
  incident upon the antenna. Further assume that the wave is travelling
  towards the antenna in the antenna's direction of maximum radiation
  (the direction from which the most power would be received).

Polarization is the orientation in field, so can I conclude that antennas that have the different polarization the effective area are equal zero?
And why effective aperture of an antenna is a parameter defined for the receiving antenna?


texts:
I'm planning my first homebrew computer. I'd like to perform calculations with 8-bit numbers. My op codes will be 4-bit numbers.
I'll be building this on breadboards so I'd like to keep things as simple as possible. This is my first attempt at anything like this -- the purpose is to learn.
So... is there such a thing as a 12-bit architecture?
Example: oooo dddd dddd where o-bits are for op codes and d-bits are for data
This system would have 256 addressable registers, each 12 bits wide. The contents of each register would be a 1-nibble op code followed by 1 byte of data.
Am I missing something, or does this sound reasonable?

EDIT for more info:
I'm trying to build something like Ben Eater's 8-bit computer.
My interest in increasing the register size is motivated by the desire to have more than 16 bytes of RAM. Ben's instructions are 1 byte long, with 4 bits of op code and 4 bits of data. Thus, he can only address 16 bytes of RAM. I figure I can do a 4/8 split and address 256 bytes of RAM, while still finding his tutorials similar enough to be useful.


texts: What cutter will work for cutting a pin off a .05" pitch pin header? I need to do this to make a 9 pin Cortex debug header and the part is so small I'm not sure even a miniature cutter will be able to fit between the pins far enough to make the cut.


texts: Real Time Clock DS1307 interfacing with Arduino Uno

texts:
I am currently working on an electronics project of building my own Digital wall clock. For that I tried making a RTC module with DS1307 IC.

I followed the following instruction from this website.

But when I tried to read and write the time to the IC using the serial monitor on Arduino software I got the following result.

My inputs were as follows:

first i/p : T000021240114

second i/p: R

Can someone help me find my mistake.


texts: non-trademarked name for Toslink connector?

texts:
My PC motherboard has header pins for a SPDIF output and I want to an optical SPDIF transmitter.
When I search any of the main electronic stores for optical SPDIF transmitter I dont get any good hits, I can find some if I search Toslink transmitter, but these are very expensive and all Toshiba branded.
I assume there must be some generic optical SPDIF transmitters, but I dont know what to search for.
Does anyone know?


texts:
I have a low frequency input signal 3-80 Hz that I am feeding into an inverting op-amp input. I am slightly confused as to what values I should choose for the following components - R3, C2, R4:

The green section is my voltage follower biasing circuit. Assuming I AC couple the signal, how do I choose the value for the high-pass filter components and DC bias resistor? AFAIK the impedance of the C2 has to be ~1/10 of the input impedance, which in this case is what? R4 (assuming op-amp's input impedance is infinite)?
Is R3 needed at all? Won't there be a high pass filter formed with R4 anyway?
Should I add a capacitor at the red junction to avoid any AC signals being passed into the non-inverting input?

As always, any suggestions are appreciated!

EDIT:

Just to make it clearer, I know how to calculate HPF values, what I would like to know is how R3 and C2 values should relate to the rest of the circuit considering that C2 is a coupling capacitor. Also, does R4 play any role in the HPF calculations?


texts: Please check my solar outlay for Lithium ion battery

texts:
I'm in the processes of 'solarising' my electric bike, and would appreciate a more experienced opinion on how I intend to do it.

The motor is a 350W running off a 36 volt battery. I intend to get three 150W panels, each rated at 12V, and wire them in series to achieve 36V.

I've found an MPPT controller unit that charges Li ion batteries.

Would this be sufficient voltage to charge the battery with?


texts:
I'm looking at this Power board of a non-working TV and noticed a ceramic capacitor with a bit of the ceramic blown away.  I'm not entirely sure if this is the reason why the TV isn't working; though it is possible.  It was soldered between the drain and the S/GND of an IC [STR-Y6456 which is a switching power supply(?)[1]]
From the markings, it's a 390pF 2kV ceramic capacitor (I'm so glad it blew on the other side instead of the marked one).
What would make a ceramic cap blow up?  While searching for this topic here, I came across [2], but that's not the case. I know a ceramic capacitor doesn't have polarity and with 2kV limit, so it can't be the voltage [though, that's just my guess] ... so I'm guessing the current has something to do with it?  What about heat?
Any clarifications appreciated,
Thanks.
[1] - https://www.semicon.sanken-ele.co.jp/sk_content/str-y6456_ds_en.pdf
[2] - Best options for limiting input ringing with ceramic capacitors


texts: What is the correct pin spacing for this footprint?

texts:
I'm trying to import an IC footprint into CAD software and can't seem to nail down the exact dimension for pin spacing. The two supporting documents seem to conflict with each other (Land Patterns here, and Package Drawings here).

In the drawings document the pin spacing in the Y-axis is listed as 0.55mm whereas if you calculate the pin spacing from the land patterns it works out to be 0.50625mm (4.05mm/8 pins == 0.50625mm/pin).

If I try to go with the 0.55mm spacing the pins seem to be out of bounds of the package size and the spacing seem to contradict with the D1 dimension (5.0 BSC).

What is the correct dimension I need? And is BSC 0.55mm, 1.1mm or something else?

Curse you Maxim and your vague schematics! (Only their drawings, their technical specs are great)


texts: Could a 220 V wire shock me if I hold a 4 band Orange Red Orange Violet resistor in series?

texts:
A noob level question and I am afraid of electric current since childhood shock.

So a wire goes into wall socket, 200v input. If I hold a resistor of 32 Kilo-Ohm and touch wire with it's other hand and at another place with my other hand, something like:

Wire end 1 ---- resistor --- my hand 1 -- body -- my hand 2 --- wire end 2.

Could I die? (I meant I calculated current, I = V/R, it's low. But am I making newb-mistake?)

What about parallel? (I do not know concept here.)

Edit

Imaginary scenario:

Guys, I am afraid of electric current. I have now started to look at electrical and electronics concepts to get over this fear. Relax, all I am trying to do is to find definitive answers which books do not provide (and not electrocute myself or someone else).

Regarding color combination.

It's not a real resistor. I picked up high enough value 32 K-Ohm, because 220/R is 0.006875A, read that it's low to kill a human and I wanted to keep the tolerance low thus 1%; did that in gResistor in ubuntu.

I will read up on what you guys have mentioned in the answers and get back with on topic but better questions.

Problem I find with books is that they tell how to calculate and what to calculate, but do not relate to real life scenarios.


texts: Damping output filter of buck converter?

texts:
Does anybody know if we need to damp the output filter of a buck converter?
I came across this paper Passive Power Filters written by R. Künzi. In this paper he suggested an approach to damp the LC output filter, but I can not understand why we have to damp the output filter of a DC/DC converter!
When we have the feedback loop,

It controls output impedance of converter. the open loop output impedance is divided by loop gain and presents closed loop output impedance. So there is no interaction between converters if we want to cascade to DC/DC converters.
Output voltage is constant, so we dont have any overshoot
So, do we need really to damp the output filter of DC/DC converter?

For input filter, it is necessary, since it can endanger the stability of converter or for 2 stages output filter (LCLC), it is needed since second stage's peak can make the gain margin worst.
Some results:
Regarding this article Stabilizing voltage mode converters with ceramic output capacitors, damping the output filter improves the phase margin. It is also useful to help us to prevent conditional stability, since the phase change is reduced by decreasing the quality factor.

Here are also a simulation with and without damping.


texts: Circuit to switch power between Battery and main Source for BLE Module

texts:
I am power a Bluetooth module (referenced as BLE) operating at 3.3v.
The module has a microcontroller inside and we want to keep the RTC working all time for scheduling, which means in case if the main power source goes down, the module will keep running on the battery.

As you can notice in this overall design, two sources to the left (mainly voltage from source and the Battery Cell c2032. The two are fed into a circuit that selects the battery in case of power absence.

I would like to inquire if there is any suggested circuit for that to switch immediately in order to to keep the timer working.

Waiting for your suggestions.
Thank you.


texts:
I bought a 16bit, 250kSPS AD7689 ADC. The circuit I am designing will amplify voltage (from 300uV up to 300mV) across a current-sense resistor (by 13x) to match 4.096V reference and feed this into an ADC. Measured voltage will either be DC or <1kHz square wave.

Do I need an anti-aliasing filter before ADC even tho I am just interested in "static DC voltage" (I am not interested in transient voltage)? If so, what should the cut-off frequency be (higher than 1kHz because of odd harmonics?)? Also what filter order should I use? 1st order seems enough to me, as 1kHz is way below half of Nyquist frequency.


texts:
I've been studying and trying to implement a PI feedback controller for a BLDC.

Right now, just to unit test the code for the PI controller, I'm driving two phases with a PWM signal on a MOSFET inverter and trying to get a prescribed current out by watching the voltage that develops on a sense resistor.

Here is the what I have the architecture:

1)  A PWM has a register value and starts outputting pulses

2)  The windings ramp up with current flow

3)  A voltage is developed across a 0.015R sense resistor

4)  That voltage is gained up by 5x through an OpAmp

5)  That voltage is fed to and ADC that samples at the exact center of each
pulse.

6)  The ADC readings are collected and averaged as fast as the pulses occur
for a period of 20ms

7)  The PID controller that I've included then takes action and that's where I'm stuck.

Ultimately, what I really want, is a value to stick in the PWM on-time register...I want a 16bit value.  But, what I'm getting in are 12 bit ADC values.

So, I said to myself, "no problem...I'm not getting current readings in, but I know what those values really are, so I'll just convert them to current!"

So, I did this:

$$ I_m = \dfrac{ADC}{R_{sense} * 5 * \dfrac{4096}{3.3}}$$

So, that's OK.  Then I go through the PI control, where we do:

$$ I_{err} = I_{set point} - I_m $$

Then, do what you do in a PI controller...Add integral gains to their past values, scale proportional gains by a scalar, and then add them up:

$$ I_{feedback} = P * I_{err} + I * \int{I_{err}}{dt} $$

This is the part where me and my buddy looked at each other and didn't know what to say...Here we're holding current feedback in our hands, measured in Amps (and a rather large value, I might add, thanks to the high gains that I've read PI controllers like to see)....But, what I need to do is put this into a PWM counter-compare register...That's a 16bit counter, not a...current register, whatever that would be!

Consider this case...I ask for 100mA and I observe 200mA...I calculate my error of -100mA, so I need to cool this thing off...I intuitively know that the answer here is to reduce the PWM duty cycle from whatever it is now, to a lesser value.

If I go through the whole algorithm, because of the negative error, that minus-sign is going to propogate all the way to my $$I_{feedback}$$....So, I leave the feedback with a negative value.  What can I do with this?  How should I apply that to a PWM register, which is the real control output?


texts: Measuring the waveform of mains voltage using an oscilloscope

texts:
I understand this is a recurring discussion, but I still can't find a concrete answer to this question.
I would like to know how can I inspect the waveform of my UPS output (230V) using an oscilloscope, to find out whether its "sine wave" is actually an acceptable sine wave or one of the high-marketing, low-quality versions.
My idea is to purchase this handheld DMM/oscilloscope and simply stick the probes on the C13 output contacts of the UPS.
There are videos on YouTube of people doing this on mains. I am knowledgeable enough to understand just how dangerous mains voltage is, and I'm aware that I'm not knowledgeable enough to understand how to measure it safely.
The only difference I see between mains and an UPS is that the UPS should not be as dangerous regarding transients, but other than that I believe they're the same thing for practical purposes. The UPS will obviously be unplugged from mains, so it will be working on battery power and it will not be connected to earth ground.
So, is there a safe way to measure the waveform of a UPS using an oscilloscope like that one?
Assuming that the oscilloscope's CAT II rating is honest, that I do not touch the tip of the probes, and that I ensure they do not touch each other, what hazards are present?


texts: which RPM measurement method is suitable?

texts: I have a PMDC motor which is electronically controlled for speed. And it is a closed loop system. A proximity sensor is there to measure the speed of the motor and there are 12 bolts attached to the shaft of the motor so that when it rotates the proximity sensor produces 12 pulses per revolution. I have written a code to measure the rpm  in which I count the pulses in one second and thus calculating the speed. But the problem is I could get a resolution of 5 rpm only. Is there anyway to get a higher resolution like 1 rpm on this system without changing the feedback technology?


texts: Nyquist theory - Control system - Stability

texts:
I am trying to understand the Nyquist theory for knowing if a system is stable. Here is what I know :
A system is unstable when the open loop transfer function + 1 of the system has one or more right half plane zeroes in the s-plane. The Nyquist contour (s-plane) is the all right half plane. When you map the Nyquist contour by using the cauchy argument principle, you plot which is called the Nyquist plot. It is possible to know according to the sense/direction of your Nyquist contour if your open loop loop transfer function has more zeroes than poles in the right half plane by counting the number of encirclement of "-1" in the counterclockwise direction or in the clockwise direction. As you can see, it needs to know how many poles  in the RHP your transfer function have to know if your system is stable. I understand that we are interesting on the "-1" point as it links to the fact that we are looking zeros in the RHP of the transfer function :
$$TF(s) = 1 + G(s)H(s)$$
We just shift by -1 thanks to a property of the Cauchy principle the origin of the w-plane for studying the transfer function GH rather than 1 + GH.
This is true if you have a transfer function under this form :
$$ TF_{Closed Loop}(s) = \frac{G(s)H(s)}{1 + G(s)H(s)}$$
with :
$$ TF_{Open Loop}(s) = G(s)H(s)$$
I think the theory will continue to work if you have a system with a non unity gain, ie :
$$ TF_{Closed Loop}(s) = \frac{G(s)H(s)}{1 + B(s)G(s)H(s)}$$
Ie, if you plot the Nyquist plot of the transfer function :
$$ TF(s) = B(s)G(s)H(s) $$
rather than the open loop transfer function
My problem is the following, suppose the feedback transfer function does not add pole or zero and it is just a constant gain and I know the how many poles in the RHP are contained in the "open loop" transfer function :
$$ TF_{"Open Loop"}(s) = B*G(s)H(s)$$
I do not know exactly what is the open loop tranfer function, so I measure it and I am only able to measure this transfer function :
$$ -TF_{"Open Loop"}(s) = -B*G(s)H(s)$$
Nevertheless my system is still :
$$ TF_{Closed Loop}(s) = \frac{G(s)H(s)}{1 + B(s)G(s)H(s)}$$
So my Nyquist plot is not the usual open loop transfer function (TF(s) = B*G(s)H(s)) and the analysis about stability is probably not the same, ie that I do not think or actually I am not able to tell that in this case, the point of interest is "-1" but as the transfer function that I plotted via Nyquist is not equal to the open loop transfer function but equal to minus the open loop transfer function multiplied by the feedback gain, why the point of interest would be "-1" and not "1" ?
I am pretty sure that the minus sign affect the Nyquist plot as it change the location of the zeroes of the transfer function but not the poles ...
Thank you very much ! :D


texts: Cycle time between flip-flops with delay

texts:
In given this circuit, how can you calculate the minimum cycle time, in order that the circuit will work properly? I need you to explain to me how to relate to Delays?

It must be something with this formula? Tclk>= Tpd (FF1) + Tpd (CL) + Tsetup (FF2) if yes,How to combine the "Delay" here?

In addition to the first example, I thought about another case. To try to understand the formula, adding another flip-flop. I am not so sure how to approach in case of  :    FF2 -> FF3, FF3 -> FF2, and: FF3 -> FF1. Can you help me?

This is correct (?):
Tper12+Tdelay1[min] ≥ Tpd(FF1)+Tpd(CL1)+Tsetup(FF2)
Tper23+Tdelay2[min]-Tdelay1[max] ≥ Tpd(FF2)+Tpd(CL2)+Tsetup(FF3)
Tper31-Tdelay1[max]-Tdelay2[max] ≥ Tpd(FF3) + Tpd(CL3) + Tsetup(FF1)
Tper32-Tdelay1[max]-Tdelay2[max]+Tdelay2[min]≥Tpd(FF3)+Tpd(CL3)+Tsetup(FF2)


texts: Does Op-Amp 741 boost the frequency of an input signal

texts: I am trying to design an electronic circuit which does the job of a dog whistle. So basically when a human whistles using the mic of the circuit, the circuit boosts the frequency to at least 50kHz or so. I am thinking to use op-amps in the circuit to boost the frequency but I am not sure if it will boost the frequency. Can anyone help me with this please?


texts: Difference in size of input and output to avrdude

texts:
When I download a .hex file using avrdude, I'm seeing a difference between the input and output size. For example, the size of the .hex file is 856 bytes, and what I see in the message is '... avrdude: 298 bytes of flash written ...'

I'm curious as to where the difference is coming from (the  .hex file is larger). And would the answer to what is the machine code size (for the corresponding source code .c file), be 298 bytes?


texts: Mesh Analysis for Current Source in between "blocks"

texts:
I can only find one equation with two unknowns.

$$-1(I_1) - 3(I_1) + 2(I_2) = 0$$

$$6\text{A} = (I_2) + (-I_1)$$

I need to find the voltage across the \$1\Omega\$ resistor. I am currently stuck on finding the current that flows through each loop.


texts: What are the functions of these capacitors in this circuit?

texts:
In the first picture, the capacitors are used in driving an inverter. In the second one the capacitor is used at the input of an amplifier.

What are the functions of each capacitor?


texts: What relay do I need to switch a 24V circuit with 3V

texts:
I have a ESP8266 which has 3V logic, and a heating system which takes 24V logic. I want to switch the heating system with the ESP8266. A relais looks to me like the best solution to do this.

However on the relais I've found like:

But I am a kind of unsure how to read the values of the relay. This one says:

10A 250VAC
10A 30VAC
10A 125AC
10A 28VDC

Does 10A 30V AC means it can also switch for 24V or is the 30V a minimal value for the output? Or do I need another relay?


texts: Replacing capacitors in older electronics

texts:
I was working on a supplementary power supply board in an old arcade cabinet. It has a capacitor with some markings that I was unable to identify and was curious if they were important. Also, I would like any advice that could help me avoid damaging the arcade.

The markings on the capacitor that I am confused by is "CE04 W". I don't know if this is just manufacturer specific or what? Accordingly, the rest of the capacitor markings are as follow:

25V 4700uf

85 degrees


texts: Is there some logic in IC name prefixes?

texts: There are hundreds of prefixes in IC names, this page lists a number of them. For some it's easy to see that they refer to the manufacturer's name, like AD for Analog Devices or LT for Linear Technology. Others can be found with several manufacturers, often three letter prefixes: SAA, SAF, SDA, TCA and TDA, to name a few. I wonder if there's some logic in this, like T** being a specific group with subgroup TD*, etc. Is there a logical structure?


texts: Emergency light circuit - What is the function of resistors, diodes and capacitor?

texts:
simulate this circuit – Schematic created using CircuitLab

I found this circuit on the internet. In this, the bulb glows when AC supply is OFF and bulb goes off when AC supply is present. So, this functions as a Emergency Light Circuit.

I managed to figure out that when AC supply is available Q1 is OFF or in cutoff region and consequently Q2 is also OFF. Hence, bulb does not glow.

Further, when AC supply is unavailable, Q1 is in ON state or saturation region. Consequently, Q2 is in active region and acts as an amplifier and makes the bulb glow.

However, what I cannot understand is the exact use of the resistors, capacitor and diodes in the circuit. I understand that removing even one of them causes my circuit to not work as I have described above, but I cannot figure out why.

Note : I have performed the simulation of this circuit in Multisim, through which I was able to verify the modes of operations of Q1 and Q2 in both AC supply on and off cases.


texts: BNC cable instead of oscilloscope probe for fixed setup?

texts:
I'm developing a device, it will generate a signal that will be fed directly to an oscilloscope, and connected permanently.

I now have the circuitry set up on a breadboard, attached to the scope using a standard scope probe. In the final product, I'd like to use standard BNC-BNC coax cable, to make it "fool-proof', and to have a very stable connection. (scope probe with its hook and ground clip can fall off when the equipment is moved)

I'm planning to design a PCB for the product. So basically the probe will be replaced with a BNC-BNC coax cable, and a PCB-mounted BNC connector.

My question is, do I need any kind of extra circuitry on the PCB to compensate for this? The maximum bandwidth I need is not more than 1 MHz.


texts:
I have the simulated signal of an MRI measurement distorted with Gaussian noise of mean value = mean signal magnitude and sd = 1% of mean signal magnitude.

How can I calculate the SNR? I think that SNR=mean signal/sd of Gaussian noise = e.g. 100/1 = 100. Is it a correct way? Could you recommend some source?


texts: How I can command the four switches without microcontroller

texts:
I try to command 2 SWitch H bridge rectifier (two mosfet two diode)  during the positive half cycle M1 switching and M2 be considered as a secondary switch that is continuously ON. During the negative input voltage half-cycle, the roles of the converter legs are swapped
So now I will try to command 4 MOSFET any person have an idea about the  new Command signal without microcontroller implementation

the two signal Pwm1 and Pwm2
I find in the internet this solution but the author used microcontroller .How I modified my circuit to obtain the same  signals  commands ?
I can used S-R flip-flop?


texts: I want to use mosfet to make a boost converter. The threshold gate to source voltage given in data sheet is 2-4 V. Then why 12-15 V is supplied? Why a resistor is connected between drain and source?


texts: I want to know the difference between Serial Peripheral Interface(SPI ) and the Clocked Serial Interface( CSI).I know that both the protocols are  serial in nature and differ in number of signal lines. I want to know when is CSI preferred to SPI and why does it has 'Clock-in ' and 'Clock-out' signals?


texts: What happens if I put my DC voltage source AFTER the diode instead of before?

texts:
I have a homework question on diodes, in which I have to calculate the Voltages across the diodes. All the questions I have encountered thus far have had the DC source BEFORE the diode. This one has the DC source AFTER the diode.

We have to make use of the Practical Diode Model in our reasoning. This is the only information they gave us:

simulate this circuit – Schematic created using CircuitLab

I have looked at other questions and websites, but most of them only explain reverse bias situations, not switching the diode and the source around. Does it actually make a difference? If so, why? Or is it just a way to confuse us?


texts: What are some of the basic FPGA synthesis algorithms mapping to LUT?

texts: I am trying to look up easy to understand papers that help explain how logic functions are mapped onto LUT. For e.g. if I have c = (a+b)*c -d how is this mapped on to LUT or if a counter is designed how is the same mapped etc.


texts: Digital sample and hold synced with a CLK

texts:
So I though this should be pretty straightforward, but apparently it's not.

Supposed we have a digital async input signal and a CLK. I want to sample the given input signal on every rising (or falling edge) of the CLK signal and output the value of the input signal when CLK event occured. I do not care about the intermediate states. I just want to have a signal that replicates the state of the input signal at a clock event and keeps that state until the next clock even.

Here is a diagram in case I am not clear enough:

I am sure that there is a simple IC (possibly from the 74xx series) that does exactly this, however, I cannot seem to come across one.

Thank you very much!


texts: What is this tube thing? (Madcatz drum pedal)

texts:
Could someone help me out, I have no idea what this tube-like thing is.

This is from a Madcatz Xbox360 drum kit pedal. The pedal stopped working and I opened the it up and found just this tube thing connected to a wire going into a controller via a 2.5mm headphone jack, that plugs into a PC or Xbox360 with a USB cable. I'm guessing it's a vibration sensor or something (for when the pedal hit's the plastic on the opposite side of this tube), and this is the only electrical component in the pedal. My best guess is that it failed and that's why the pedal isn't working, and I hope it can be replaced. The cord seems fine to me.

Photos: http://imgur.com/a/ab4DP


texts: What can be used to provide -5V potential to a circuit?

texts:
What can be used to provide -(minus) 5 volts in the circuit diagram  given in the link below?
Also can someone highlight what is the purpose of zener diodes?

Simple digital meter using ICL7107


texts: How does LIDAR avoid getting confused in an environment being scanned by hundreds of other LIDAR?

texts:
(Meta: I do not know an appropriate place for this on Stack Exchange. There does not appear to be any groups related to autonomous driving technology and computer 3D vision / perception systems.)

For self driving vehicles using 3D depth perception LIDAR on a highway with hundreds of other vehicles also using various other LIDAR sweep beam or spot-field (kinect style) emission scanners, how is it able to distinguish its own signal returns, from the scanning being done by the other systems?

For an extremely large multilane highway, or complex multi-way intersections such emissions can be seen in all directions, covering all surfaces, and there is no way to avoid detecting the beam emissions from other scanners.

This seems to be the main technical hurdle for implementing LIDAR for autonomous driving vehicles. It does not matter if it works perfectly if it’s the only vehicle on the road using LIDAR.

The real question is how it deals with being inundated with spurious signals from similar systems in a future scenario where LIDAR is present on every vehicle, potentially with multiple scanners per vehicle and scanning in all directions around each vehicle.

Is it capable of functioning normally, can it somehow distinguish its own scanning and reject others, or in the worst case can it fail completely and just report garbage data that is useless, and it doesn’t know that it’s reporting garbage data?

This at least seems to be a strong case for having passive 3D computer vision that’s just based on natural light and stereo camera depth integration, as is done in the human brain.


texts: What is the output voltage of this simple circuit?

texts:
Background: I'm trying to learn circuits from http://www.electronics-tutorials.ws but no practice problems are provided so the problems I find to work are out of order from what I've learned so far. How would you find the output voltage and current below:
The silicon diode has a .7v  diode drop:

Specifically, I don't understand what to do about the grounded branch and the non circular path followed by $v_0$.
(Answer :- 2.07 mA, -0.45 V ).


texts: Should the clock from a PS/2 keyboard be used in a Verilog always block?

texts:
I'm trying to get a Verilog design for interfacing with a PS/2 keyboard to work but I'm having very strange issues. I have a fairly simple always block which controls everything:

always@(negedge PS2_CLOCK) begin

    if(rst == 0) begin
        state <= READY;
        index <= 0;
        keycode <= 0;
        data <= 0;
        is_pressed <= 0;
    end
    else begin
        case (state)
            READY: begin
                state <= GRAB;
                is_pressed <= 0;
            end
            GRAB: begin
                if(index == 7) begin
                    data <= (data >> 1) | (PS2_DATA << 7);
                    index <= 0;
                    state <= PARITY;
                end
                else begin
                    data <= (data >> 1) | (PS2_DATA << 7);
                    index <= index + 3'b1;
                end
            end
            PARITY: begin
                state <= DONE;
            end
            DONE: begin
                is_pressed <= 1;
                state <= READY;
                keycode <= data;
                data <= 0;
                index <= 0;
            end
        endcase
    end
end

As you can see, this executes based on the negedge of the PS/2 clock but I'm not sure if that's a good idea. Every once in a while when I push a button on the keyboard, I fail to receive the data correctly and I think it's because of uncertainty in the clock signal. Here are two executions of the code when a button is pressed:

The first is of a correct execution of the state machine while the second has a clear disruption in the clock signal. In this case, it wasn't very damaging but if it occurs near the end of the data transmission, it often causes my machine to skip a state and get out of sync. Any advice would be greatly appreciated.


texts: I'm implementing a buck boost converter. I need a variabe duty cycle with constant frequency of 200kHz(without using a ardino board in which I suppose I would have to upload a program everytime to get a new duty cycle ) to drive the igbt. I was thinking if using a opm comparator with one input as Vref with a potentiometer to get variable duty cycle and  another input as a constant frequency sawtooth wave from microcontroller . But can i  give such high frequency wave to opm in the first place n get a decent pwm signal? Isnt there another way ?


texts: Polling vs Interrupt: which one is first in a bare-bone piece of hardware?

texts:
First of all, I must say that I have a computer science background, and I don't have much knowledge about hardware. I would like to ask this question because in software, what I often see is a loop, e.g: while loop, for...loop...

In my understanding, polling is like you check for an event occur every certain amount of time (might require the use of clock?)

Interrupt is like we don't care if it "loops" or not, when the event comes, it will "signal"...

What about in hardware? What is actually equivalent to a "while loop" or "for loop" in hardware? I assume it is a mix of polling and interrupts...but I wonder which one is really first? Isn't it it that when we check for something, we must poll it first? (maybe I'm a bit biased on polling here).


texts: Switch load using toggle switch or switch button

texts:
The fact is after designing my own dc-dc converter (0.8v-20.5v 5A max) I decided to add a switch load button in order to connect/disconnect the load only after setting my desired voltage.
I could use a simple toggle switch button but generally their bounce enough on the first 100ms so that why I want to search for another design.
I've been searching some implementations but all of them uses an n-channel mosfet that's for me its perfect, but the problem is at voltages like 0.8v-3v the design is not suitable due to mosfet gate voltage minimum.
I want to make an implementation like this kind of button in keysight power supply

What I need is when voltage is at 0.8v for example if I turn on the toggle switch, output voltage be 0.8v and so on.
Its important that the implementation be capable of handling 5-6A.


texts: Reducing power supply ripple for GSM modem

texts:
I'm powering a SM5100B GSM modem from a 5A bench supply (peak current is 2A). The required supply range is Vmin=3.3V, Vnom=3.6V, Vmax=4.2V, so I'm giving it 4V. Every so often, the module will reboot (a problem I've had with all three GSM modules I've tried: this, SIM908 and ADH8066). I presume that it's a power issue. My power is not dropping below 3.3V, but I saw in the SM5100B data sheet that the maximum ripple is 50mV\$_{PP}\$ for freq <200kHz and 2mV\$_{PP}\$ for freq >200kHz. I have a ripple that's generally around 40mV, but it does spike upwards sometimes. I put it on my DSO in pass/fail mode with a 50mV\$_{PP}\$ pass rule:

I get a chirp every two seconds or so, and they look to spike up to about 100mV or so. I thought I might be able to fix the problem with a couple of capacitors, so I added a couple of 16V 1000\$\mu\$F electrolytics across the power supply rails on the breadboard, close to the GSM module. Unfortunately, it doesn't seem to have made the slightest bit of difference. What else can I do? Is the ripple really likely to be the problem, or am I chasing a red herring?


texts: Do comercial spectrum analyzers show a single-sided spectrum?

texts: If I use a Bessell function to compute sidelobe power - do I need to double this power to get the power I will read on the specan?


texts: ESP8266 not running uploaded Arduino sketch

texts:
This is my first time using an ESP8266 WiFi module, and I'm having a lot of trouble just setting it up. My goal is to get the module to run a simple Arduino Blink sketch so that I could proceed to writing more complex code.

I'm using an ESP-01 module and this
USB to Serial breakout board.

I then learned from this video tutorial that I had to make changes to the original breakout board so that the module could be programmed. These changes include soldering a connection between the CH_PD and VCC pins, and soldering a button between GPIO 0 and ground. The idea is that the button must be pressed when inserting the breakout board into the PC so the ESP enters programming mode; when released, the module can supposedly execute the uploaded code.

Here is the breakout board with the changes made:

Due to lack of buttons, my teammate and I crudely soldered jumper wires instead, connecting them together and disconnecting them to simulate pressing and releasing the button, respectively, as shown below:

In Arduino IDE, I have the board set up like so:

and I'm trying to upload and execute this sketch:

void setup() {

  pinMode(LED_BUILTIN, OUTPUT);

}

void loop() {

  digitalWrite(LED_BUILTIN, LOW);
  delay(1000);
  digitalWrite(LED_BUILTIN, HIGH);
  delay(2000);

}

The code is supposedly uploaded to the ESP as shown by the output below:

Regardless, the module doesn't seem to be executing it, nor any other example sketch I tried for that matter. The module would briefly flash blue when inserted in programming mode, and would flicker blue as the program is being flashed, but then nothing else happens on it.

Other notes:

When setting up the Arduino IDE, I downloaded the 2.5.0-2 beta ESp8266 platform.
I tried connecting the breakout board directly into the PC's port and to a USB extension to see if there was any difference, and there wasn't any.

What am I doing wrong here? If there is a better solution, what is it?

Thanks in advance!


texts: Designing a filter: does the order i which we cascade the sections matter?

texts:
So I am designing a 4th order lowpass filter using two biquadratic sections.
I decided to split the gain evenly between both sections.
After some calculations, one of the sections has a quality factor of 0.9 and the poles frequency is 1.65 kHz, the other has a quality factor of 4.6 and the poles frequency is 3.4 kHz.
My question is, in terms of design, is there any difference the order in which I cascade the sections? Their quality factor is so different, I wonder if I should put first the lowest or the highest quality factor? What should be the criteria here?


texts: Changing a 3.3V signal to a 5V signal using a BJT transistor

texts:
I saw someone asking this EE.SE question in a thread over 2 years old and could not really understand some things about the answer.
He had a 3.3V input signal that he wanted to change into 5V signal.

This is a circuit someone suggested:

Here is a comment he made about the circuit:

  [...] the transistor is configured as an emitter follower and the voltage on the emitter is base voltage minus about 0.6V. If the emitter got higher it would turn off the transistor thus preventing the voltage rising much above about 3V. Think of base and emitter and what differential voltage they must be at to sta[r]t to turn the transistor on.

What I don't understand is:

What is Vb when there is 0V in the emitter? I know that Vbe = Vb - Ve, and that Vb is supposed to be 0.6V, but why? There is the 3.3V supply in the base, doesn't it contribute anything? Vb is determined only and only by Ve?
Pretty much the same question but about Ve. If there is a voltage Vb that is set by the 3.3V supply and the R1 resistor, there is supposed to be a Ve according to the equation in (1). But if Ve is set by the 0-3.3V input - isn't there some kind of a clash?
Why is the transistor off when the input is 3.3V (in the emitter)? According to the equation in (1), Vb is supposed to be Vb = Vbe + Ve = 0.6+3.3 = 3.9V. That means, the base has '1' (high), which means the transistor should be on, no?
I assume  the 3.3V supply is limiting Vb to 3.3V, but I'm asking anyway.
Any reason why the resistors have these values?

Thanks!


texts: Induction motor field oriented control software timing

texts:
I have studied several application notes and technical literature regarding field oriented control of three phase induction motors. Based on that I have encountered that there are two main approaches as far as timing of the control software.

One approach that I have found is that the free running timer periodically starts A/D conversions of
two phase currents and dc bus voltage. The frequency of the A/D conversions is several times greater then the pwm frequency. The interrupt service routine associated with the end of conversion then contains whole current control loop and at the end updates the duty cycles for the pwm.

Another approach that I have found is that the A/D conversions of two phase currents and dc bus voltage are synchronized with the pwm duty cycle reload events. The frequency of the A/D conversions was usually one half of the pwm frequency. Again the interrupt service routine related to the end of converstion contains the current control loop. This approach repeated in more cases then the first one.

In my opinion the first approach is better because it reduces the transport delay of the control loop and ultimately increases phase margin of the control loop. Thus I do not understand why the second approach is more frequent. I have probably missed something. Does anybody know the answer?


texts: Why are a primitive polynomial equations used in linear feedback shift registers?

texts: A real-world shift register uses lets say 4 bits, and it shifts each bit +1 from least significant to most significant. Its a simple formula. When reading up on these, why do they use or are defined by confusing equations such as 1+x+x^4?


texts: Camera sensor to accept or reject the position in which a component is kept on a machine

texts:
The factory where I work has a hole punching and labeling machine, that basically needs to punch holes and stick labels onto a plastic container. The most important aspect is that the container needs to be placed in the correct orientation or else the holes and labels will be made on the wrong side.
This operation is highly dependant on the operators. The container cannot be modified to incorporate any foolproof mechanism as the die has already been made. The container does have a branding image molded onto it. I was wondering if I could use a controller and a webcam placed in a position to identify the branding logo. If the logo is identified then the container is in the correct orientation else the machine stops and raises an alarm. I have some basic knowledge of electronics and programming but need help with direction.
Would a raspberry pi be a useful controller to work with industrial machines or are there powerful boards that can be used for this purpose, would not want to invest in a plc though. I just want to test the idea out and check if I can make something work first.
Edit 1:
The color of the molded branding is the same as that of the background which is black.
Thanks for your time and support!


texts: Why can you measure input and output impedance of a amplifier circuit with a resistance/potentiometer?

texts:
While running simulations for a circuit I measured the input and output impedance by simply adding a potentiometer, turn it up until the voltage peak to peak signal going out reached half and then supposedly the resistance then is the same as the input impedance. Why is it that you can do this? It becomes a voltage divider circuit or what?
The circuit


texts:
Looking at my phone charger:

  Model LG MCS-02EP

  Input 100-240 V, 50-60 Hz, 0.2A

  Output: 5.0 V 0.85 A

That means input power from 20W to 48W and output 4.25 W. Thus, an efficiency in transfer of energy around 10% - 20%, losing up to 90% of the energy. It seems an illogical waste of energy.

I can assume 0.2A has a peak, but then same peak should be mapped to the output or must be consumed by the power adapter itself (when and where?)


texts: Dynamically allocating memory for an embedded application

texts:
I am working on a Project that will requires using an MCU to receive frame packets with unknown frame length on reception, but each reception has an octet from which you can deduce the number of frames left to receive and hence calculate the length of the entire frame.

In other to avoid allocating a fixed memory for the receiving frame which might not be used up (if the receive frame length is less that the Max frame length to receive), I am of the opinion to dynamically allocate a memory for the remaining frame to be received.

For example. If we assume a packets of 20 octets and the 3rd octets tells you the number of the remaining octets left to be received (which could be 2, 3, even 17 octets max). Rather than creating a register of size 17, which might not be used up, how can I dynamically allocate this memory especially for an embedded application, so that if the 3rd octets revels that there are 6 octets to be receive, then I simply allocate a register with size 6 for the rest of the frame, with out using the "malloc".

Programming language is C.

I hope my question is clear enough. Please share your views as I need to best possible approach on this.

Thanks.


texts: Aliased signal has phase shift due to Nyquist

texts:
Let's say I have a pure sinusoid at 135MHz and I am sampling at 150MHz (so fin < 2fs). So now in my first Nyquist zone, I will see a 15MHz alised component.

From my understanding, the 15MHz signal and the 135MHz signal will look the exact same when sampled. I read somewhere that, they will have a phase shift though.

Where does the phase shift come from, and is it not possible to use that phase shift to distinguish between the two?


texts: What sensor to inspect for object motion detection in an open but limited space?

texts:
I'm playing around with motion detection for fun and came across the problem of detecting the motion of uniform objects (e.g. cubes, balls, etc) from a fixed position. Concise: electronically capture the path of such a small object that enters an open empty space (field, flat ground, no other objects).

QUESTION: What sensors do you employ to fulfill the following requirements (within the given enrionment).

Environment and scenario:

empty, cubic space (air only),
no side longer than 40 feet / 12 meters.
different but natural outdoor or indoor air pressure.
no temperature difference between object and sensor.
temperature between 5° and 55° celcius
objects enter space from one side of the cube only.
sensor must be opposite of the object entry side.

Requirement:

location of object must be captured highly frequenty (min 10 times)
within 1-3 seconds.
each measurement event must deliver x, y and z (full relative position to the sensor).
the sensing angel must be 80° (from what I read, that is really high. However, I think that can be resolved by installing multiple
sensors to reach the 80°.)

So, dear e-engineers. What sensor is to solve that problem best under the given conditions? ultrasonic sensors?

Thanks for hints (that go beyond my concrete question).


texts: RC522 has other pins than shown in all the tutorials

texts:
I've bought an RFID RC522 module which I intend to use with my Raspberry Pi 3B+. I read the following tutorials and I noticed that their modules have other pins than the one I bought:

https://www.raspberrypi-spy.co.uk/2018/02/rc522-rfid-tag-read-raspberry-pi

https://medium.com/coinmonks/for-beginners-how-to-set-up-a-raspberry-pi-rfid-rc522-reader-and-record-data-on-iota-865f67843a2d

https://www.raspberrypi-spy.co.uk/2018/02/rc522-rfid-tag-read-raspberry-pi/

This is my RFID module:

It has the following pins (in case it's not readable in the photo):

VCC RST GND MISO MOSI SCK NSS IRQ

The modules used in the tutorials have the pins

3.3V RST GND IRQ MISO MOSI SCK SDA

Is the module just deprecated (2012)? Which pins of the module should I connect to which GPIO pins?

Thanks in advance!


texts:
I am using easydriver 4.4 to control stepper motor. Easy driver takes input voltage from 7 to 30V. I fed 20V 3.0A to easydriver, but i got it burnt (easydriver)*. Is 3.0A too much for easydriver ? What is the rated input current for easy driver ?

* Edit1


texts: 3.3V Power Failover Supply with USB Li-Ion Charger

texts:
I am currently designing a "3.3V@500mA Power Failover Supply with Integrated USB Li-Ion Charger" for a uC project. I want the circuit to draw power straight from USB power when available & switch to battery operation when USB disconnected.

I found some similiar design on the web Chronoduino v0.3 & Simple USB temperature logger, but I wasn't convince they will work efficiently as the final VDD33 output from battery will always higher than output from 3.3V regulator (as shown below), hence power will always drain from the battery & charger will always keep on charging the battery + supplying power to the external load too; reducing the life-span of the battery.

Chronoduino design

I redesign the circuit above & would like someone to take a look at it & provide some feedback if I can improve it further (or anything I did wrong in this design).

My design

The components I choose are Microchip's MCP73831 for Li-ion battery charging, 3.3V 500mA LDO MCP1825S-33 & 2 pass diodes.

My area of concern:

Can anyone recommend me what SMD diode (D1 & D2) model should I use?
I tried Schottky diode MBR120VLSFT1 (Vf=0.3V, Ir=0.6mA) but it
seems causing problem to the charger IC whereby charger LED keep indicating
charging even though battery has been disconnected (possible due to
high reverse current from these diodes causes current leaking back to the BATT pin?).
Should I use a MOSFET switching method for the power failover? if
so, how should I modified this circuit and what MOSFET is recommended?
Any further improvement OR mistakes in my design?