texts: How to properly read Watt of a bulb power?

texts:
I'm confused about reading the terms Watt, Wh, and Ws of bulbs. Here is the quoted text taken from an electrical book that I'm currently reading on :

Now I'm take out some points from the remarks that confuses me:

60 W-bulb consumes 60 Wh in 1 hour.
100 W-bulb consumes 1 Wh in 1/100 hour.

My questions are :

Why does a 100-w bulb consume 1 Wh in 1/100 hour, instead of 100 Wh in 1 hour? (Like that one in the case of 60-W bulb)
Is 60-Wh equivalent to 60*3600 Watt in a second?


texts: Derivation for the skin depth of a wire given RF signal

texts:
I was looking at the equation for the resistance of a wire under RF signal and failed to produce similar results.

On WikiPedia article on skin effect this resistance is given by:

$$R = \frac{\rho L}{\pi D \delta}$$

Can anyone please explain how the bottom corresponds to the area of the wire?

Recall that for a wire under DC current we have:

$$R = \frac{\rho L}{A}$$


texts: Why would data transferred through an extension cable be different

texts:
This is something that has been bothering me especially when dealing with the latest cables made for DisplayPort or HDMI.

I understand that issues can occur with adapters since you might be dealing with analog / digital signal. However I sometimes encounter problems after adding a simple extension cable.

For instance, I have a Mini-DP port that output to a 4K device properly using an adapter. I added a Mini-DP extension cable in-between the 4K adapter and the output source and suddenly only a QHD resolution is possible.

How is this possible? All the pins are present, shouldn't it just work the same as if it the signal was taken from the source?

Attempting to find cables seems impossible with all the misinformation.

In summary, is there anything more going on or are we just dealing with faulty cables / scammers most of the time (By scammer, I assume they would be putting connectors without fully connecting them to preserve costs or falsely advertise their merchandise)


texts: Can I use network cable for low voltage DC power?

texts:
I'm a guitar player with a crazy idea for a 2 part bypass looper:

Enclosure A is just big enough to house 4 footswitches and an ethernet jack.

Enclosure B has 9V DPDT relays to route audio ins and outs. (9VDC is standard for guitar pedals)

Can I run power through CAT5 from the power source in Enclosure B to the switches in Enclosure A to make/break power to the coils of the relays back in Enclosure B?

The power supply would be one of 3 things: a 9V battery, an adapter with an output of 9VDC 500mA, or a "OneSpot" style adapter with an output of 9VDC 1700mA

The idea is to have a small controller mounted on the pedalboard with the larger enclosure hidden underneath, so the cable would only need to be 6ft at the most.

Could network cable handle this? Is there another compact solution that would be better? Any advice is appreciated.


texts:
I'm simulating a SystemVerilog based core on Vivado 2019.1. I can copy the value of any signal simply by select+right click+Copy Value, but when I select multiple signals (for my case I need to select about 15000 signals belonging to the same array), Vivado disables the Copy Value option.

Is there any way to select and copy multiple values from wcfg window?
If not, is there any way to save the values that the signals included in the wcfg window take at a specific time of simulation?

Thanks.


texts:
I'm looking at the following datasheet for an accurate TCXO: TG2016SBN

It gives values for Rload and Cload, and AC coupling cap - which I've incorporated into a clock pulsing circuit. Will a simple comparator (with a bit of hysteris) be enough to clean this signal up for a CMOS clock input?

I've currently got the following circuit sketched up. The 20Ks should will give a paralel (small signal) load of 10K, and bias it at 1.65V DC coupled. I don't see anything wrong with it - the comparator is fast enough and in theory work.

The comparator is the following: LT6752

Cheers


texts: How a laser ranger finder actually works on an odd surface

texts:
I am trying to learn something about LIDAR sensors or Laser Range finders. But I am always getting confused how could it get works.

What I understood about the principle is it emits a laser (invisible laser) which gets reflected back to sensor and mcu calculates the time of flight based on reflection which all happens in a fraction of seconds.

But how the ray always get reflected back to the sensor?? I mean if it falls on a flat 90 degree plane, it gets reflected back. But on a 45 degree it gets reflected in a different direction and the sensor wont get it.

So how does it really works??


texts: Energy usage of LEDs (always lighting and dimming vs always on)

texts:
I'm going camping and have lots of LED string lights connected to their own little solar panels. I need to make sure that the lights run all night and was curious how LEDs and these electronics might work. I'm curious on ideal lighting mode because I have the thought in my head like "it's less efficient to turn off a car engine at every stop light than to just leave it running." So is there any way to know if the lights will last longer if:

1) they are overall on less or less bright than fully on? There options for dimming and brightening constantly or flickering etc. Either of these modes will have the lights less lit overall than option 2.

2) they are on full brightness all night? Does it cost more energy to control the lighting modes than to leave it on?

Hopefully my question is clear. Thanks.


texts: Why doesn't my bench PSU read current on a breadboard?

texts:
I've recently purchased a cheap eBay DPS3012 DC-DC converter supply. I intend to use it on breadboard projects.

The "problem" is that the meter reads a 5V output, with no current being drawn and therefore no power. However, the LEDs and ICs are working properly. I'm guessing it's something to do with breadboard characteristics.

I'm sure there's a relatively simple answer for this, I have done some research but haven't found a satisfactory answer.

Thanks for the help in advance!


texts: Decrease a voltage from 24-27VDC into 18VDC using a 7812 and a bunch of other home supply parts

texts:
I have one 7812 1A linear regulator, bunch of resistors and zeners at home.

My input voltage is 27VDC from two 12V lead batteries. Desired output voltage is 18V and the
maximum current consumption of the connected device will be 100mA.

I'm considering using a zener diode at the GND pin of regulator.

schematic: https://www.circuitlab.com/circuit/ue4t8a/elsov_linear_regulator/

What adjustment current trought the GND pin on regulator I have to expect?

Do i need the 1uF capacitor when using lead batteries?


texts:
I'm trying to understand how Vg is calculated in this circuit below.  I understand the current mirror is meant to protect the SMPS from current flowing into the output of J2 if the 12V source is not present by ensuring Q2 is open.

I have modelled it in LTSpice below using a resistor for the load but the IR6 doesn't match the IR7.  Even without the load the IR7 is still not equal to IR6.
How do I derive VG for a given load?
Note: Q1 in the schematic is a DMMT5401 which is a matched PNP pair in a single package.  The LTSpice model uses 2 DMMT3906 to simulate the matched pair.


texts: Can PGA be cascaded to amplify small signal?

texts:
I need amplify small 50Hz AC signal. The range is from sub mV to hunderds of mV. Can I use multiple cascaded PGAs?

Something like: signal_source => PGA205 => PGA204 => PGA204....,


texts:
I seem to have a little confusion regarding changing the fuse bits on a new ATmega8 AVR.

A brand new AVR comes with 1 MHz internal RC setting and there's no CKDIV8 fuse bit. Also since ISP programming should be done at less than 1/4th the speed of MCU, initially I have to program at < 250 kHz.

Now my question is when I plug in the AVR to the power source and wire up the SPI connections, and want to change the clock to 12 MHz external crystal do I first program the new fuse bit settings into the AVR (with no crystal connected) and then connect the 12Mhz crystal to the XTAL pins (along with the caps) or connect the crystal  and then program the required fuse bits?

Also when one is programming an AVR, does it need a power source or does that come from the ISP header itself?


texts: Simple resistors, inductors first order circuit

texts:
Asuuming the following circuit has been turned on for a long time:

I need to find the current Il=current that goes through the inductor.
I know that the indoctor acts as a short circuit, but i still can't figure how to calculate the current.
I was thinking that all the current goes through the inductor, but that still doesn't make sense and doesn't help me solve.
Any tips/help would be really appreciated.


texts: I have recently stumbled across thermoelectric coolers, it is my understanding that when they are powered one side will get colder and the other side will get hotter. Also that the more power supplied will mean increased cooling on one side and increased heating on the other side of the device. However I was wondering how efficient the thermoelectric cooler would be at cooling something like a chip if a heat sink or fan was not used to cool the hot side. I am referring to thermoelectric coolers which are 40mm by 40mm in size.


texts:
I need an explanation about the leading and lagging power factor at electron level.

Case1:
In a inductor it has the lot of free electrons are ready to move when we applied a voltage(AC or DC). If we apply a alternating voltage to a inductor, a change in current with respect to time is passing through it. According to induction principle, a change in current produce a change in magnetic field. So that a change in magnetic field produce a induced  emf. This emf opposes the change in current wich was supplied by a alternating potential and which was causes of that emf.

Here My first question is for inductor: How the electron flow lags behind the supply voltage?

Case2:
For a capacitor there is a dielectric medium between two plates. The dielectric medium itself has the randomly oriented dipoles. So that the net electrostatic force is zero. When we apply a potential between these two plates, the potential start to align the randomly oriented dipole's positive sides towards in which plate the electrons are accumulated and the negative sides of the dipole towards in which plate the electrons are pulled away.

Here My question for capacitor is: How the electron flow (current) leads the voltage?
(according to electrical laws potential only causes of electron flow. So without a potential the electron flow doesn't possible. How the electron flow leads the voltage in capacitor?)


texts: What is the voltage and current of a shorted secondary of a transformer?

texts:
So let's say you step down 120 volts with a current of 0.1 amp, to 12 volts with a current of 1 amp transformer.

What does is mean exactly when the current steps up to 1 amp in my example? Does this mean when you short circuit the secondary, you will have 1 amp of current (neglecting dc resistance of coil)? What about with the DC resistance of the coil?

Or does it mean that you can only draw 1 amp total from different loads set in parallel?


texts:
I need to find Norton's equivalent for the following circuit:

Why can't I just take the open-circuit voltage and the short circuit current, divide voltage over current and thus obtain the equivalent resistance? My textbook gives no explanation at all.

(I tagged thevenin because there isn't a norton tag)

Open circuit voltage:

\$\ 10-3*i_a+2*i_a-6*i_a=0  \$

\$\ V_o=6*10/7 \$ volts

Short cirtuit current:

\$\ 10-3*i_s-5*i_s=0\$

\$\ i_s=10/ 8\$ amps

This is apparently wrong.


texts: How are other chipmakers keeping up with TSMC if their processes are just the best?

texts:
In the news recently was Intel's stock falling 20% because its 7nm processes are being delayed by 6+ months. The argument seems to be that Intel is already behind (since they're using 10nm processes while TSMC is on 7nm processes, soon to be 3nm processes), so it's only going to get worse for Intel. The entire chipmaking process isn't something I understand very well however, so I'm hoping someone can enlighten me.
Why exactly is it important to be on 3nm processes instead of 5nm or 7nm? This article says:

There are a few major underlying technologies that dictate the potency of any chip. The most fundamental rule of processors still holds true: The densest process nodes, provided they have decent power, performance, and area (PPA) characteristics, will often win the battle if paired with a solid microarchitecture.

I'm guessing this means that 3nm processes are "better" because for whatever reason I don't understand, it fundamentally improves the PPA characteristics. In other words, although you can improve while on 10nm processes, you'll never catch someone on 3nm processes - sort of like how a 40-year old can run faster with training, but will never catch someone who's 25 years old.
But if this is the case, then TSMC's processes are just the best in market, and they'll be leaving everyone else in the rear-view mirror. That hasn't happened though - the same article notes that Intel's processors still leads in certain categories, such as overclocking and gaming performance. Somehow Intel has managed to remain competitive with TSMC in spite of poorer technology. Even more surprisingly, SMIC manages to rake in billions of dollars in revenue in spite of using only 14nm processes. Perhaps one could say "therefore their revenues are going down", but they aren't, and that's in spite of Intel/TSMC/Samsung being on 10nm and smaller processes for years. Can someone explain what's going on?
I'm sure there are other applicable tags than just "Intel" and "fabrication", but I genuinely don't know what they are - if you do feel free to edit them into the question.


texts:
What is the purpose of Debounce Functional clock on AM335x processor? In the technical reference they say: "The de-bounce clock is used for the de-bouncing cells". What cells? I am little confused with this.

Technical reference http://www.ti.com/lit/pdf/spruh73 page 4868


texts: Determine the orientation of an ESD protection chip

texts:
I have an ESD protection chip that has been unsoldered from my board, and for which we have lost the orientation. (I.e. we don't know where pin 1 is - the little dot has gone.)

Because of the symmetry of the IC's package, there are two possibilities for the orientation. Is it possible to use a voltmeter or scope to retrieve the orientation of this part?


texts:
Summery: I am trying to figure out if I can use a bilateral switch as if it was a tiny relay capable of communicating UART signal, or are there things I am missing. Now, the long explanation.

So, I never used a bilateral switch before. The problem I am trying to solve involves having 2 devices which have one UART port each share one UART output port. Basically I have a UAV drone with a Flight Controller (FC) and an On Screen Display (OSD) units. During flight I want the FC to talk to OSD via the UART. However, on the ground, on occasion, I need to connect to either the FC or the OSD via their respective UART ports to update software, etc.

So basically I am shooting for the following states:

S1: FC <-> External Port
S2: OSD <-> External Port
S3: FC <-> OSD

To do this I figured I could use 8 bilateral switches in this kind of arrangement:

I want to use the Texas-Instruments CD4066BPWR (Datasheet: ti.com/lit/ds/symlink/cd4066b.pdf). And this is the way I would like to connect it up:

What my question boils down to is do I properly understand how bilateral switches in general and this particular IC in particular work. If I substitute the bilateral switches with tiny relays my diagram should work just fine. But with bilateral switches are there any catches I am not seeing, such as for instance if they do not work at high frequencies? I don't need them to switch quickly, but I do need them to communicate high frequency data signals (standard serial speeds).

Also, I can't figure out if I need a set of resistors to pull the control pins low to disconnect the connection? And when disconnected, will the IN/OUT pins just float with circuit potential or will they be pulled low or high, or stay in the last known state or something strange like that? I am treating these bilateral switches as if they were relays basically, but am I wrong to do so?


texts: Is it allowed to stop and restore I2C transmission? I would like to stop it in different periods of transmission and then after for example 500ms restore it to the state when it was stopped. I'm thinking about enabling and disabling SCL transitions. If it is allowed, is it a bad practice?


texts: Why am I given two reactances for a synchronous generator?

texts: I'm solving problems on the alternator and some of them give a reactance Xq in addition to the usual synchronous reactance Xd. Does anyone know what this Xq is?


texts:
I had been attempting to desolder some SMD ceramic capacitors off a PCB to measure their capacitance. Unfortunately I am quite new to soldering and have managed to screw up.

The below picture shows one side of a removed capacitor, with the base plate which is typically attached to the PCB attached to the capacitor instead. I am very concerned about how I would attach this capacitor back in place, as it is important that the board works after I examine it. Simply sliding it back in place and testing continuity with a multi meter does not show connection, and I am doubtful soldering the capacitor to the still good side would change that.

I had desoldered the cap by heating both sides, then laying the tip to the side of the cap to heat both sides at once, then give it some force to push it off. I had also managed to break off a part off another capacitor with a similar method and it appears that cap might not be working anymore. I am using a very cheap soldering iron for what its worth.

In short I am asking what options I might have to reattach this cap and have the circuit working.


texts:
I made a traditional PWM signal generator using a 555 timer IC.

However, when I connect the output (pin 3 of the 555) to my oscilloscope and set it to AC coupling, the signal shown on the display is around -5V and 4V.

I know that I should set my oscilloscope to DC coupling but I'm wondering why there is an AC signal since I powered the circuit with a DC source. (9v battery)


texts: A low power circuit to measure large resistances

texts:
I am trying to measure resistances in the range 20 kohm to 1 Mohm. Initially, I was using a constant voltage source, but the power consumption when the R = 1 Mohm is very large.

I want to use as little current as possible. I need to measure the resistance value using a microcontroller (that has an A/D input).

Should I be using a constant current source and then sense the voltage across the resistor to be measured? That would mean that I need to tune the circuit for the max resistance I want - otherwise, the output voltage would exceed the A/D pin spec of my microcontroller, right?


texts: How to generate constant movement given variable opposing resistance?

texts:
I need to generate constant movement in one direction given a variable opposing force even while "stalled" (no net movement in either direction) and when the opposing force is greater than the force being generated, e.g. [try to] constantly move at a speed of 6 inches per second in one direction given 0-500 lbs of opposing force at any time with the ability to compensate for changes in the opposing force within half a second.

My research led me to three phase induction (torque) motors and optical incremental encoders, but I have neither the knowledge nor experience to ensure these will work for my application.

Any insight would be appreciated!


texts:
Is it possible to  make a sepic converter of 120 W using LM3478 ?
I am trying to make  the circuit in TI web bench but it is not supporting over 12V 3A in LM3478.


texts: build a minimal Radio transmitter with an atmega8 microcontroller

texts:
I guess I can use an atmega8 microcontroller to build a simple radio transmitter maybe using one extra simple component (such as a transisitor not another complex component like another IC). The radio transnmitter would be used to transmit binary somehow (not audio or speech). I guess it would use the internal oscillator somehow.
So my question is is there a circuit that uses only an atmega8 and a simple wire (for the aerial) to build a simple transmitter? If not what the minimal circuit, with an atmega8, to transmit binary information? There are of course various way to encode binary information.


texts: Charging two lead-acid batteries connected in series, separately (with two solar panels)

texts:
I have two lead-acid batteries connected in series to produce 24V. They are powering an audio amplifier.

I'd like to be able to charge them while they are powering the amplifier, with solar panels.
Can I connect a solar panel in parallel to each battery, separately?

I made a drawing to illustrate what I'd like to achieve:


texts: Record video from webcam w/o microcontroller

texts: I managed to salvage a webcam from a broken laptop, and I'm looking to use it to record video in a small package to attach to a rocket. However, I need to record the video to some data medium like a usb drive or SD card. How would I go about recording camera data to an SD card or flash drive without special hardware like an Arduino? Is there some kind of board I can use specifically for this purpose? Even better, is there a way I can salvage a component like this? Thanks!


texts:
I'm currently working on a simple audio amplifier circuit using the TDA7052 IC.
So far I have been able to achieve amplification, with a little distortion.

My problem is that I'm observing a large DC offset at the audio output, and the IC is getting very hot.

I'm feeding in 12Vdc and the amp is drawing around 100mA, which makes for 1.2W of power. The gain is set to 20dB with pin #4 being driven at 1Vdc.
Here is my circuit:

And here are the input and output waveforms (Yellow waveform taken at pin 8, with reference to system ground):

So, the input is being driven with a signal generator with the parameters displayed. The output is indeed being amplified, but it has a DC average value of around 5V, how do I remove this DC offset? and is there a way to mitigate this slight distortion?

I've tried adding two 10uF caps in series with OUT+ and OUT-, this is what happened: (and I'm not surprised, the datasheet doesn't show them in the typical application circuit, nor do other implementations found on the internet).


texts: What's the purpose of the diode at the JFET gate in this Hartley oscillator?

texts:
This is something of a follow-up question to one I asked a few days back (Original JFET Hartley Question).  Having made the changes suggested in the comments (i.e., changing Rd/R3 to 270 ohms, instead of 270k) and some basic biasing tweaks, I finally got the circuit oscillating on the board.

However, at the high end of the tuning range (around 2MHz), I noticed that the sine wave was distorted.  Not grossly distorted, but it had flat tops and a slightly breaking wave shape.  I felt the layout was adequate and I went looking for other problems with the circuit, turning to similar JFET designs (something I probably should have done at the start!)

The modified circuit I came up with was the following:

The resulting sine wave was very good, with little distortion throughout the tuning range.  But, the single most effective change was the introduction of D1 at the gate of the JFET.  I haven't had much luck looking for a decent explanation as to why this diode makes a difference.

The best I could find was this snippet from J Carr:

All very fine, but how exactly does it "clean the signal"?


texts:
I am looking for a DC barrel to power a battery pack. The battery in question is connected in 10S3P, that's is a nominal voltage of 36V. I am currently looking for a DC barrel that can withstand at least 42V and currents up to 2A.

I have seen some companies that charge the battery pack using a RCA plugs, however would like to avoid using them because they are not design for that. I have check DC plugs but I can hardly find that can withstand 42V or higher. However, most of them are design for 24 volts.

I was wondering if I could use them as long as I maintain the power output within the safety threshold. Let's say that the dc plug has is designed to safely withstand 24V and 5 A. Could I used with 42 volts and 3 amperes. If not, what would be your advice?


texts: automatic datasheet information extraction

texts:
Does anyone know of a way to extract information from a datasheet table ? An example of what I'd like to do is automate the comparison of a given characteristic (say V_dss) from multiple MOSFET datasheets (PDF, may be from different vendor).

The aim is to simplify the obsolete components replacement, a task that I will have to do regularly from now...


texts:
What is the main difference between mic input and a guitar input? is it only the source impedance seen in the input of the amplifier?
I am designing one pre-amplifier in which i need to input both mic, line and guitar, so for better performance i may have to use an impedance matching section to match the source impedance of all these inputs to input impedance of pre-amplifier IC right? (I am analyzing this from an electronics engineer point of view) correct me if it is not applicable to audio connections.

can someone tell me how these inputs differ in their impedance ?

I am referring THAT Corporations design note DN-140 as my primary reference but it is only dealing with mic and line inputs, can some one tell me how the guitar inputs differ from line inputs ?

does the Guitar input pads are used for this impedance matching ?

if someone can share some guidelines for this, it would be helpful for me..


texts: Components on both sides of the board with reflow

texts: Is it possible to place components on both sides of the board if I'm doing DIY toaster-oven style reflow soldering? I would think that doing the reflow twice (for the other side) might overheat the components already soldered on.


texts: Understanding a simple opto-isolator circuit

texts:
I have this circuit that is part of a schematic that I am trying to read.
I have some idea, but I am not sure that I am correct. All I want is to figure out the D0 and D0_3V3 values.

For example assuming that the circuit that is connected to left D0 is set to low (no voltage), will D0_3V3 will be 0 (low) or 1 (high)? (I don't care for real measurements as this is either high or low, as if this is on a micro-controller circuit will get voltage or not.)

The bottom part with the R11 and +3V3 gets me confused as it seems to keep the NPN transistor always on, which it cant be.  And if the NPN is always on then there's always high signal at D0_3V3?

Thank you very much all and sorry for making a such a newbie question!


texts: What difference between two discharge resistors in two circuits?

texts:
When I search for 220VAC led indicator, I found two circuits

one from here circuit 1

another here circuit 2

The purpose of R1 from two circuits for discharge C1 when main AC off, but is there any difference between two type of connections? In circuit 1 R1 connect between two AC line, in citcuit 2 R1 connect parallel with C1


texts:
I have below design and want to know it is correct or need to change anything.
Details are as below
Input voltage is from 18V to 40V and can draw only 2mA current from source voltage.
so I have current limiter using PNP.
But ratings of coil are 8.4V, 10.5mA.
Can attached circuit will work?
Please advise, let me know your comments
Thank you.


texts: HD44780 LCD - proper addressing for overseas 16x4 line display

texts:
I bought a few 16 character by 4 line LCD's from ebay that are HD44780 compatible and today I was testing them.

The LCD advertisement is at: http://www.ebay.ca/itm/LCD-16x4-1604-Character-LCD-Display-Module-LCM-Yellow-Blacklight-5V-Arduino/401053633069

Various sources (including http://www.raviyp.com/embedded/142-16x4-lcd-line-addresses) tell me that:

  For displaying the characters on the 1st line send the command 0x80
  For displaying the characters on the 2nd line send the command 0xC0
  For displaying the characters on the 3rd line send the command 0x94
  For displaying the characters on the 4th line send the command 0xD4

I did use these codes for specifying the beginning of the line. The first two lines of the display are correct but the last two lines are always indented in by 4 spaces (with the last set of characters missing) no matter what I display on the screen.

For example, If I wanted to display "0123456789ABCDEF" on the first or second line, all of it will fit and be displayed. However, if I tried it on the third or fourth line then I would see "    0123456789AB".

Upon examining the LCD module circuit board, the only labels I see are the pin definitions on each side and on the back side, I see a big label "1604A".

I'm tempted to try 0x90 for the 3rd line and 0xD0 for the 4th line, but before I do, is there a way to know regardless of the display I use which addresses represent the start of each line?


texts: Decoding circuit with transformer topology

texts:
I am studying a circuit used for mobile adaptor, where AC to DC conversion is done through bridge rectifier ABS210. Transformer is used for isolation along with IC LP3783 (Offline PSR Driver) and LP3520 (Rectifier).

Circuit as below:

I want to know which SMPS topology is used here?


texts:
I am a complete novice when it comes to electrical engineering; however, I'm interested to know the capability of accelerometers.

In addition to capturing data on distance traveled, etc. - is an accelerometer capable of capturing impact/shock (i.e. if attached to a shoe, could it capture the number of times the shoe kicks a ball for example)? If so, would the accelerometer have to directly be impacted or just in the vicinity (i.e. placed anywhere on the foot it would it capture the impact of a ball hitting the foot anywhere)? Also, would an acceleromter be capable of determining between walking/running and the impact of an object hitting the foot (i.e. a ball)?

Thanks in advance.


texts: dsPICDEM MCHV-2 Development Board motor connection

texts:
I have dsPICDEM MCHV-2 Development Board and three phase induction motor. I don't
know how to connect the motor to the development board. I have connected three
lead wires of the motor to the three outputs designated as M1, M2 and M3. But
where should I connect the protective ground of the motor? I haven't found answer to my question in user's manual. Thanks in advance.


texts: Why is my RF circuit behaving like this?

texts:
I am not an RF engineer but play one at work. I am working in uhf SatCom. In the lab, In order to test two radios communicating over a satellite, I built a small RF circuit out of cots components. I basically put a mixer between the two radios and inject the delta of the uplink and downlink frequency ( one radio also has discrete inputs and outputs so I use a circulator to split that out). Finally there are some attenuators so I'd do not blow anything up.

Here is the strange thing. I can use this circuit for most of my testing when I operate in SBPSK 2400bps. Also in CPM 2400 - 56kbps. BUT, if I operate in FSK 16k, the receiver will not get the transmission. No RX shows up.

Then I noticed that if I unscrew the N connector JUST enough ( most likely when the center connector is no longer engaged) but the shell is still on, reception all of the sudden works perfectly fine. I am currently TX at 24dBm and I have 33dB of attenuators. The receiver sensitivity is -10dBm to -80dBm. I "think" I tried it earlier with a different setup with 50dB attenuation with the same results.

My theory is that it is now tiny antennas vs. a solid connection. What is causing this? And is there another RF component that I should put in to properly replicate this condition? If so what is it called?


texts: KiCad Eeschema Annotations: Prevent numbering for certain components?

texts:
I'm a music electronics hobbyist, and am in the processes of switching from Eagle to KiCad.
For some components — particularly potentiometers — it doesn't make sense for the name/reference property to be numbered. As it stands, though, if I name the volume pot "VOLUME" KiCad insists on renaming it "VOLUME1" before checking rules, generating netlists, or exporting to Pcbnew.
It's a pain to undo the numbering and edit the references on the PCB silks.
Is there some setting I can't seem to find to prevent this, or some other best practice?


texts: CC430 - NodeMCU I2C Communication Problem

texts:
I'm trying to communicate CC430 microcontroller based board with ESP8266(NodeMCU). I can communicate in one-direction e.g. NodeMCU to CC430. However I can't send any character CC430 to NodeMCU board. What could be the problem? Connections are done properly e.g. Vcc--> Vcc , GND --> GND , SDA --> SDA , SCL --> SCL .
There are also pull - up resistors. I tried the Arduino to NodeMCU communication , there is no problem with that. However neither Arduino nor NodeMCU can't get any character from CC430 side.
Code is given with link : https://dev.ti.com/tirex/explore/node?node=ALKC78J64Cwe6EXqBJh1DQ__IOGqZri__LATEST


texts: ACB vs Contactor for synchronous generators

texts:
I've been told by an experienced electrical engineering colleague that it is preferred to use an ACB rather than a contactor for making and breaking the connection to a synchronous generator, but he can't explain why.

So, for any power or generation engineers out there: What are the pro's and con's of an ACB vs contactor for synchronous generator applications and WHY?


texts:
I've got two ethernet ICs that should be put back to back with reverse MII mode. For this, I should cross the TX and RX pins and the application note of the reverse MII chip says, the TXER and RXER pins should also be crossed.

The problem is just, that the reverse MII PHY offers the RXER pin but the normal MII chip (LAN9500AI) doesn't offer a TXER pin. Since I couldn't find anoymore information for the LAN9500AI: Should I connect the RXER pin to another pin of the LAN9500AI or leave it open?

Thanks!


texts:
I'm looking for a smart way to connect two PCB's in a cheap manner. I would prefer not to use any external components for the connection (if possible).

The PCB's are rather small (20 x 20 mm).

Do you have any idea?

Best Regards,
Andreas


texts: What does an oscilloscope's input resistor and capacitor do?

texts:
I watched a YouTube video on how to use an oscilloscope, How to Use an Oscilloscope.

It says there are 16 pF of capacitance and a 1 Mohm resistor connected in parallel on each input port of the oscilloscope. However, I still don't understand why there's a capacitor and resistor inside, and what the purpose of those things are.

Why are those things in there on the input port? What do they do?


texts: How do I properly size the components for an RC filter?

texts:
Background

I'm filtering low-speed signals from some 5V automotive sensors.  That is, their signal is within 0-5V and less than 1kHz.  As such, I have selected a 1.3Kohm 1% resistor and a 0.1uF C0G capacitor, giving me a corner frequency of around ~1.2kHz.  Both are 0603 packages.

The Real Question

What I am curious on is... is there more to the filter than just the values?  Does the package size of the RC components influence filtering, one way or another, based on the frequencies, or even voltages, that I'm working with?  Aside from things like microphonics or temperature-based fluctuations (which I'm trying to deal with by going with C0G capacitors, etc)... is there anything else I should be looking at more closely?


texts: Altium Designer: mixed mechanical layers on Top and Bottom Layer Pair

texts:
I have a multilayer board I'm working with. To ease placement and routing, I created some layer pairs and two Layer Set (TOPSet, BottomSet) and then I clicked on hide/show button to assign meaningful layers to each set. That worked fine with Signal, Overlay, Paste & Solder layers but I have a problem with mechanical layer 1 and 13.

In my design ICs are placed on both sides of the PCB. This doesn't show well on 2D layout Mode (3D obviously works fine as there isn't any trasparency). Some components at the top have their "violet" box assigned to Mechanical Layer 1, some to Mechanical Layer 13. This is also true for bottoms components.

How can I fix this problem so each component has the correct mechanical layer assigned based on its side placement? This question is similar to this one, but I cannot figure out how to solve what colin explained in his last comment: Assigning mechanical layers in Altium

Exactly, how can I delete Layers Pair with components already placed? I receive an error (there are primitives in it). If I change that pair to have other layers associated, then I'm able to delete it but then what colin explained doesn't work for me.

Thank you!


texts: High 4bit crash in atmega128 serial communication

texts:
I am trying to communication between atmega128 and serialCom(PC),

but I get a pretty strange bug.

When I send data 0 to 255 (char) from atmega128 to serialCom(PC)

,after sending 0x08, the high bit is crashed. (07 -> 18)

For better understanding, I attached picture about the bug.

It is my first time coding in AVR, So I couldn't find where is my bug.

Here is my source code.

#include <avr/io.h>
#include <util/delay.h>
#include <avr/interrupt.h>
#include "header.h"

unsigned char rx;

void Putch(unsigned char local_data)
{
    while(!(UCSR0A & 0x20));
    UDR0 = local_data;
}

char Getch(void)
{
    while(!(UCSR0A & 0x80));
    return UDR0;
}

void main(void)
{
    UCSR0A = 0;
    UCSR0B = (1<< RXEN0) | (1<<TXEN0); //UART0 Rx,Tx On
    //UCSR0C = (1 << UCSZ01) | (1 << UCSZ00) | ( 0 << UMSEL0) | ( 0 << UMSEL1) | ( 0 << UPM00) | ( 0 << UPM01);
    UCSR0C = 0x06;
    UBRR0H = 0;
    UBRR0L = 103;
    unsigned char flag = 0;
    int i = 0 ;
    while(1)
    {
        flag = Getch();

        for(i = 0 ; i < 255 ; i++)
            Putch(i);

        _delay_ms(5000);
    }
}

If you have any idea about this situation, please comment for me.

thx.


texts: How does adding a current source and extra resistor to source follower improve its performance?

texts:
This question is similar to FET - Source follower utilizing current source to lower voltage offset, although I do not entirely understand the explanations, which is why I am posting my own question.

As part of an electronics lab, I was asked to build the following circuits.

I started with a simple follower:

There was a constant offset from the +12V DC power supply, which makes sense. The goals were to remove this offset and increase the follower's gain. First, we were told to replace the source resistor with a current source:

And the gain increased substantially! I believe putting this current source in place of the resistor decreases signal attenuation that the JFET causes. I'm trying to understand why this is. Adding the current source stabilizes the current, and it makes sense that this could remove some signal attenuation, but how? Is it simply that the current source allows the circuit to more easily reach its equilibrium point?

This is only half the story. We also had to remove the offset. To do so, we added another source resistor to the upper leg of the circuit:

Now we have identical resistors above and below where we're measuring the output voltage. This is starting to look like a voltage divider. I was talking to one of the TAs in lab and he agreed that the voltage divider helps remove the +12V DC offset, although I'm not entirely sure why. Horowitz & Hill actually gives this exact scenario, and this is what they show:

In the other post I linked above, the reasoning (as I understand it) was that as  increases, a negative voltage grows across the JFET. How even much Vin increases is however much the negative voltage the JFET acquires. This causes the equivalent voltage drop across the upper resistor, so  in will go down by the same value of  that it went up.  is also equivalent to the voltage drop across the bottom resistor. Mathematically, this is:

      =  −  −  =

I'm not entirely understanding this math and how it follows what I wrote out above. I know that to remove the offset, we want  = , but I don't understand how what I wrote above actually amounts to this. So  goes up by  and we have  + . Then it goes down by the same amount from the bottom resistor and then down by the same amount again from the bottom resistor. How does this effectively cancel out? Also, Horowitz & Hill says something similar: we start with  +  and drop by two . Again, how would this cancel to  = ?

Thank you for helping me understand this.


texts: Voltage source connected to single inifinitely long wire

texts:
I have in my mind a thought experiment which I cannot figure out.

Imagine a voltage source working on let's say 1 GHz. One end is connected to a ground, which is very small (we can abstractly assume it is just a point in space) and keeps constant voltage, 0V. The other end is connected to infinitely long single wire.

I wonder how different parameters like input impedance, radiation, voltage and current propagation are gonna look like.

If there were two paralell wires, there would be an electromagnetic wave travelling between them, no mistery about that.

Is there gonna be any propagation in a single wire case? If yes, I would be pretty sure that it would include a lot of radiation and, at some point, all the energy would be radiated off. The question is, how far can the signal go? Also, I'm wondering what would be input impedance in such a case? It would have to be resistive if radiation occurs, am I right?

I'm getting really mixed up about this because I know that propagation over a single wire is impossible. Is it really? Or is it impossible because of radiation? What I mean is that maybe (that's what I don't understand) voltage can propagate over a single wire but at some point it would radiate all the energy off so effectively, propagation over single wire can be regarded as "impossible", because we have very strong limitation - radiation.

I get even more confused when I think about it from the perspective of Maxwell equations. I know that close to the source, there would be E vector between two ends of a source. How would E vector look if the voltage propagated over a single wire far away (like 1 km)?

I hope some of you could clear things up for me :)


texts: Why exactly do you need a LCD controller board to interface LCD to a microcontroller?

texts:
I've dealt with interfacing a very simple LCD display with a microcontroller, so I get the basic concepts. I'm trying to interface something a bit more involved.

I'm a bit confused on why you would need a LCD controller board to interface a LCD that displays nothing more than simple characters (no graphics). Take this LCD from Electronic Assembly for example. It has a table of command for the LCD controller SSD1803. Does this mean I cannot interface this LCD screen without a lcd controller board to my microcontroller?


texts: Can a stepper motor flyback diode discharge a coil when connected in serial to the coil and opposite to the current?

texts:
On a circuit taken from this page http://www.opend.co.za/tutorials/steptut1.htm

The last circuit shows two diodes positioned in reverse polarity to the current.

It is supposed to protect against the inductive kickback of each coil when its driving transistor is turned off.

But when one transistor is closed and the diode is not connected in parallel to the coil (as most flyback diodes I've seen) how can a closed circuit be formed between the two sides of the coil to discharge it?


texts: How fast does a 64-bit multiply or divide execute on an FPGA?

texts:
When using a regular FPGA such as Xilinx Spartan 3 or Virtex 5, how many cycles does a double-precision floating-point 64-bit multiplication or division take to execute?

As far as I understand, the FPGA does not have a hard FPU and you need to create one using the standard IEEE libraries or other materials. This means that it won't execute in a single cycle, so I'm looking for a rough estimate to compare the performance of a 100 Mhz CPU with a 100 MHz Spartan/Virtex FPGA.

I'm primarily interested in floating-point operators, but if you have experience with integer operations that would be appreciated as well.


texts:
I am using the Shockley model to evaluate the current through a diode and the voltage across it and I have this circuit and this is where I am stuck:

simulate this circuit – Schematic created using CircuitLab
How can I write the equations of voltage and current such that by using the Shockley equation we will have a n-th order system?


texts:
I posted a question recently regarding PID controllers, and it was swiftly answered.

I began to work up a Simulink model and I'm running into problems with my (simplistic) model. I want to work out the kinks with this mass-spring-dashpot system before actually completing my more complicated task.

Below is an image of my Simulink model. It has a set point loaded in from the workspace; the error signal is pushed through a PID controller. The output of this PID controller is "supposed to be" current, so I pushed it through a saturation block to limit the maximum amount of output current.

I then amplified it with a gain equivalent to the motor constant (noting that torque is proportional to current in a DC motor). To the output (which should be some sort of position), I added additive white Gaussian noise.

There are a few problems with this simulation.

One, the output of the motor is torque, not force. This, however, is a minor concern and because this is just an example I was working up to rationalize the concepts in my head, does not matter.

The real concern is the output of the PID controller. Based on my motor specifications, the maximum allowable current is about 10 A, so I set my saturation filter to cut off at -10 A and +10 A. However, using the fancy "tune PID" feature in Simulink, I'm getting absurdly high values for the controller coefficients. This, in turn, results in absurdly high values for the controller output, much greater than 10 A.

Clearly something is going wildly wrong here, and I'm not sure what. I require my rise time to be ~0.1 seconds (for a step input), and this results in values like 10^8 for the integral coefficient. I conjecture that my assumption that the output of the PID controller is current is wrong (after all, the PID controller in Simulink doesn't know what I'd like it to output), but I'm not sure how to remedy this.

Any help is greatly appreciated. ^^

For reference, I'll indicate what my constants are here instead of giving messy MATLAB code.

m = 1 kg;
k = 98700 N/m;
c = 10.5 kg*m/s;

I_max = 10 A;
I_min = -10 A;
kt = 1.08 N*m/A;

Which resulted in values of:

K_p = 1285705;
K_i = 184757940;
K_d = 1983;
N = 23914;

EDIT: To avoid any confusion as to why I'm inputting x_set into my PID controller, let me clarify. I'm not ignoring everything said in my previous question, but instead I'm assuming I have some means to use a 1 V/m converter, so that I can be lazy and let my position in meters be equivalent to my input in voltage to the PID controller.


texts: Whilst cutting up a USB cable for a project I noticed this extra bare wire within the insulation. Now I'm assuming the foil is shielding of some sort, but do I need to connect this bare wire to ground? Or should it be left disconnected?


texts:
Can I please have the solution to this problem?

I promise this isn't a question in an assignment that I just want to copy lol. I had this in my quiz and I want to see if the solution is the same as mine.

ZTH is looking into the circuit from the voltage source therefore the load here is the voltage source so we remove it.
What about Vab?


texts:
I am sorry for questioning the "law of conservation of energy" first of all.

The expression for the output voltage of the LM317:

Vout=1.25*(1+R2/R1)

contains no any relation to the input voltage. It doesn't care what's the input voltage. It only cares about the two resistors R1 and R2 (in my simulation). Increasing the value of R2 increased the output. But once I get the output equal to the input, further increasing the value of R2 doesn't increase the output voltage. What is the factor that doesn't let the output voltage go beyond the input voltage. I know it won't go (law of conservation of energy) but why?

I have attached the snippets of the output voltage for two different values for the R2 resistors.(I don't know whether those large valued resistors are available. Please bear with me for this simulation)

Edit: So its all the matter of 'Minimum Dropout voltage' (Vin-Vout). But going through this datasheet shows the difference of -0.3 which indicates higher output voltage.


texts: What's the difference between a hardware register and a shift register?

texts: There are two different wikipedia articles but they don't articulate the difference very clearly. Is the main difference that the shift registry uses a clock?


texts: During festivals and marriages I have seen some decorations with LEDs which are hundreds in numbers (see attached image). Could you please provide some insights on the ICs used to drive such LEDs in large numbers. Also on the methods to sequentially light the LEDs.


texts: USB power in Parallel, increasing the maximum current using a Y splitter idea[POWER ONLY]

texts:
When you connect batteries or power sources of the same voltage, in series, the voltage adds together. When in parallel the capacity of the two add together.

Ive seen a few usb>sata cables in which there are two usb cables at one end. One for data+power and one for the extra power that larger HDD 3.5inch needs.

So my question is. If I treat the usb ports on my external battery as seperate sources of power, if i join the positive of port 1 to the positive of port 2 and then to a Micro usb cable. The same with the negative. This puts both sources of power/ports in parallel. This is confirmed by the face that if one port breaks the circuit is not broken.

By connecting them in parallel I should increase the capacity. In micro usb battery bank or whatever you want to call it. Capacity is measured in Ah or mAh. 1Ah is 1 solid amp for 1h. So by joining these two ports in parallel, I cant increase the total capacity as they are both the same battery. But should this increase the current.

The above was just to get the idea going, what im planning to do is below

Another mod I have is to take a usb hub, with ONLY a Usb cable with a usb male connector on it. Slit the cable open half way, find the red and black wires and make a T junction out of both. connecting the extra cable I just added to a male usb port that will go to my battery (usb power bank). Im joining 5v to 5v, whats the problem, the power system is working in parallel (because the hub can take it from a pc or the battery) and the data pins are unaffected. Allowing me to take a LOT more current when nessesery. Meaning I could hook up like 12 Hard drives or charge a few phones quickly. This being current each device will only take what it needs?

Any thoughts or issues spotted. What im aiming to do in total is that I have a windows tablet, but it only has a micro usb 3 port, im gunna use an adapter to make it into one female usb3 port. then give it some power by making a t junction to my power bank (it will be fixed to the back of the tablet) and then will go to a usb3 hub also on the back of the tablet:: http://www.amazon.co.uk/gp/product/B00Y25XFGK/ref=ox_sc_imb_mini_detail?ie=UTF8&psc=1&smid=A2PGPJL0BBLHLX

Not important but the power bank is "Anker® 2nd Gen Astro Pro 15000mAh Triple Port "

Im also using its 9v port to extend my windows 8 tablets battery to about 16-20 hours by my estimate

just to check and reduce peoples time that I waste (apologies in advance)
Im only touching power pins, so I do not think I need the processing chips in smarthubs or whatever
Its current so it does not matter how much I supply, each device "Should" take what it needs.
The voltage is identical from both sources. Only the current is different as the pc provides 0.5A and the charger 1A and 2A ports.


texts: Finding current in s-domain. Please help?

texts:
I need to find the current going through the inductor \$(I_l)\$ for \$t>0\$ using Laplace circuit analysis, to then find \$(I_l)\$ in the time domaine.

simulate this circuit – Schematic created using CircuitLab

I came up with the following way of finding \$(I_l)\$ using current divider.

\begin{align}
I_L (s) &= \frac{Z_{total}}{Z_L} \cdot I_{total}(s)\\[0.7em]
&= \frac{Z_C + Z_R + Z_L}{Z_L}\cdot I_{total}(s) \\[0.7em]
&= \frac{s^2 + 2s + 1}{s^3}
\end{align}

and then to find \$ I_L(t) \$ I would do

\begin{align}
I_L (t) &= \mathcal{L}^{-1}\{I_L(s)\} \\[0.7em]
&= \mathcal{L}^{-1}\left\{ \frac{s^2 + 2s + 1}{s^3}  \right\}\\[0.7em]
&= \frac{t^2}{2} + 2t + 1
\end{align}

Could someone please tell me if I did it the right way ?


texts:
I have come across some electronic engineering papers from the mid 1970's where they were testing tunable phase shifters.
To measure the phase shift they used a vector voltmeter. As this is not a bit a kit I have come across or is as readily available as an oscilloscope around the university, I am curious as to what advantages or drawback a vector voltmeter might have compared with an oscilloscope, if we are considering phase measurements?

Is there any particular reason you might choose one over the other or might this just have been equipment that was available at the time and suitable for purpose?


texts:
I am an electronics hobbyist who has started dabbling in making circuit boards for my projects.

I have designed and fabricated a board for a solar powered sign I am making.  The sign essentially consists of a Li-Po solar charging circuit (using a LT3652 chip), a boost converter (using a LTC3426 chip), and a Atmega328P-AU controlling some Neopixels.

I am a bit stumped at this point with my latest circuit board revision.  The Atmega part of the board receives power from two sources:

A 9-12VDC jack, which powers a 5V linear regulator.
The solar/3.7V Li-Po setup.

When there is power present at the jack, it powers a linear regulator and at the same time activates a relay.  The relay disconnects the batteries/solar/boost converter system from the Atmega side of the board, while connecting the output of the regulator.  This part WORKS.  When powered from the jack, everything operates normally.

Problem

However, I am having some issues when attempting to power the Atmega from the Li-Po batteries.

The sequence of operation for this circuit is:

Power from the batteries is connected through the normally closed contacts of the above mentioned relay.
That trace is connected to the source of a P-channel MOSFET.  The MOSFET gate is pulled low by a push-button, which powers the 5V boost circuit from the drain of the MOSFET.
The 5V boost circuit powers the Atmega328P, which then holds the MOSFET gate low, through an opto-isolator.

This set up worked on a previous revision of the board, however I did not have the opto-isolator.  The resulted in voltage from the battery back feeding though the Atmega when the MOSFET was off (pulled high).

When the N.O. start switch is held closed, everything appears to operate normally.  When the switch is released, the Atmega appears to be holding the MOSFET gate low, but the Atmega becomes unresponsive (stutters, restarts, hangs).

It seems to be a hardware problem, as it does this regardless of what sketch is loaded (or what is in the sketch).

Question:

What is wrong with my circuit design/implementation that could cause the issues described?

What I've tried

The Atmega runs fine and holds the MOSFET gate low if I remove the LTC3426 from the board (so that the 5V rail is being powered straight from the battery through the Schottky diode).

I tried replacing the LTC3426 chip with a second one that I had on had, with the same results.

If I remove the opto-isolator and 10k pull down, and jumper through the 1K load resistor and pads 1 and 4 of the opto (while changing the programming of the Atmega to reflect this), the everything also appears to operate normally (as it did in the previous revision).

Here are the schematics:

from here

I also bought a scope, but I haven't developed the knowledge base yet to know much of what I'm looking at:

Battery voltage at rest (measurements taken at MOSFET):

Battery Button Pressed (everything working):

Battery Button Released (not working):

5V feeding the Atmega with button pressed

5V with button released

And this is the output of the inductor feeding pin 1 of the LTC3426:

Pressed:

Released:


texts: How to safely measure VCEO or VCES of a transistor?

texts:
As an example, NPN Silicon Power Transistor TIP31 VCEO (Collector-Emitter Voltage) is rated at 40Vdc Maximum. I have many unknown transistors for which I would need to measure the VCEO. Many are power transistors, many are low power.
Is there a safe way to measure VCEO (or VCES) of a transistor? (avoiding to fry the unit)


texts: Circuit Protection to the current circuit

texts:
I have a basic circuit that uses 555 timer to generate PWM signal and the PWM signal turns the high side switch, SI1865DDL, on and off at certain frequency and duty cycle. The output from the high side switch goes to a camera which then takes photo. Both the high side switch and the 555 timer, are powered by a single power supply that outputs 5V, 1Amp max.
Power Supply:

Here is a block diagram

I will use a IN4148 diode for reverse protection. I would also like to mention that I have turned the system on for an hours, and it worked fine. What sort of protection can I use on the output of the power supply to maintain at 5V 1Amp?
So, I was able to find a tvs diode that I believe fits my need: uClamp0871P. Can anyone please verify if this is a good tvs diode for a 5V power supply? I understand that it clamps at 15V which I am fine with it as it has low steady state power rating under 8V.


texts: How can I replace a relay with a MOSFET Transistor?

texts:
I have this working

simulate this circuit – Schematic created using CircuitLab

An Arduino commute both relays and a power adapter charge each battery at a time.

I would like to replace each relay by a MOSFET. How can I do that?

I think the solution bellow will not work because DRAIN is always connected to SOURCE and this will short circuit batteries. MOSFETS only isolate from SOURCE to DRAIN.

When the D9 is HIGH, D10 will be LOW so the power adapter will never be charging both batteries simultaneously.

simulate this circuit

Sorry for the messy schematic.

Thank you very much.


texts: symbolic circuit analysis in Sagemath/Mathematica with graph theory/incidence matrix?

texts:
Looking for how to go from graph theory directly to solve circuit/nodal analysis.
This link has been helpful: graphs and circuits but I seem to be getting lost in the graph theory part.  SPICE must do something like this numerically, is there  any documentation on the design/algorithms that SPICE uses?

I can build a directed graph in Sagemath/Mathematica by adding vertices/edges.

Sagemath will return the incidence matrix. Or you can enter the incidence matrix directly but for something like a netlist it can be a lot easier to enter nodes, ie. vertices of the graph.

Resistances/impedances go into a diagonal matrix R, known voltages/currents go into a vector.

I'm not clear on finding the spanning tree/re-arranging the incidence matrix.
Seems like this should be some standard graph theory or linear algebra functions. You eliminate one row/column and should have a matrix A =[ At I ]
where At = edges in the graph spanning tree and I = n x n identity matrix.


texts:
Sorry if this is about the newbiest question on this site,

If I were to draw a graphite trace on a piece of paper (which from what I know would have some amount of resistance), and connect a multimeter and 9V battery to it as shown below:

Assuming that an electrical charge flows from - to + and takes the path of least resistance, how would I redirect the charge to go from contact A to contact B, instead of contact A to contact C (effectively shutting off the multimeter), without shorting out the 9V and putting it at risk of catching fire?

Thanks in advance!


texts: recharge AGM batery with 3 phase charger and 277 volt power

texts:
I'm helping set up a system for a 3 year project measuring storm water runoff. This is my first project recharging batteries, any comments suggestions and questions will be very helpfull.

We have access to power from a 277 volt street lamp that turns on at night. We are planning to reduce power to 120 volts using a transformer, possibly this transformer, then connect a 3 phase charger possibly this one. will I need anything besides a transformer to do this?

When the power is turned on each night the charger will recharge a 12V AGM SLA deep cycle battery which will need to store enough power to run 3 Raspberry Pis for about 15 hours a day. The standard charger for a Raspberry Pi is 5.1v 2A. We are looking into switched mode power supplies to efficiently lower power to the 5V 2A our Pi's require. Any suggestions about switched mode power supplies? could I take one out of a wall charger and use that?

I have read that they draw between 700-1000mA depending on what they are doing, our Pi's wont will probably be drawing closer to 700mA. Could we safely get away with supplying less than 5v 2A? Will a 100aH battery be sufficient?

Thanks,
Danny


texts:
In the effort to understand early computers (systems revolving around the 6502 CPU). I have started studying their makeup, while the operation of the CPU & memory makes sense. I'm left stuck and confused when it comes to how all of this was interfaced and displayed on a TV.

Analog video as I've found out is a complex problem all on its own. So I've decided to start simple.

I want to design a simple Monochrome Composite Video Driver - Its only function will be to produce a white screen - However, to really understand the functionality I want to use technology only available during that time period.

My theoretical understanding (PAL):

I need achieve composite sync. To do this I need to address:

Horizontal Sync
Vertical Sync
Color Burst --- Can possibly leave this one out?

General PAL Timings:

Line Period: 64 us (Micro Seconds)
Line blanking 12.05 +- 0.25 us
Line sync 4.7 +- 0.1 us
Front porch: 1.65 +- 0.1 us
Burst start 5.6 +- 0.1 us after sync start.
Burst 10 +- 1 cycles

General Specifications:

CCIR/PAL standard video signal has 625 lines/frame and it repeats @ 25 frames/sec.
Each frame is split into 2 fields; - each consisting of 312.5 lines, called odd and even fields. Thus field rate is 50. i.e. CCIR /PAL std has 50 fields/sec rate.
Interlacing: The lines of odd-even field lie alternately . This method of scanning is called interlacing. This interlaced scanning is used to reduce flicker while displaying the image on a monitor.
At the start of each Horizontal Line a sync pulse is fired.
There are 625 Hor Sync pulses per frame.
There are 50 vertical sync pulses per second.

To achieve a monochrome display:

I need to address intensity/luminance (Y Signal --- Don't have too much info on where this 'Y' signal comes from)

0 Volts = Black Level
0.7 Volts = Peak White Level

What I don't understand:

Lets assume I can put together the V/H sync pulses and the timings are perfect.

How do I assign a 'White' value to each and every pixel? Where does that 'information' come from?

Lets say the first H sync pulse is fired and the TV is now aligned and ready to draw the very first pixel on the first line (Hopefully I have the understanding right).

It is now time for the TV to see a voltage of +0.714 V to make that pixel turn white.

Does the electronic circuit now switch to a different sub-circuit to retrieve this picture information?

I have a digital mindset at the moment and see the operation in this fashion: The driver does the heavy lifting analog work to align the TV...and then the circuit looks elsewhere to see what color this pixel needs to be and thats my source of confusion where does that +0.714 V come from?

Disclaimer: Aside from what I've included here - Assume I know nothing more. I don't have any prior analog video experience.


texts:
simulate this circuit – Schematic created using CircuitLab

I1 is an wilson modified current source by 4 pnp transistors. SW1 and SW2 are doubts. When SW1 is open, SW2 must be closed and vice versa.

I have only one control that is the variable source V1. When V1 = 3.3 V, then I1 = 15mA... and when V1 = 0V, I1= 0mA.
For example, when V1 > 0.7V, SW1 is closed and SW2 is open... when V1 < 0.7V, then my load is grounded.

My question is, which are the best components to use in SW1 and SW2? BJT or MOSFETS? I need to implement this with discrete components. I'm using 2N3906 on my current mirror and a 2N3904 to control the current on it.

If I use BJT's for SW1 and SW2, will change the current form I1 to my load?


texts: Diagnosing possible SMPS feedback loop failure

texts:
I work in a theatre and I'm looking for some guidance on how to solve an issue regarding a 24V power supply in one of my LED lights. The model is a Chauvet SlimPAR QUAD 12 IRC, to be exact, consisting of 4 sets of LED channels(red, green, blue and amber). With budgets as tight as ever there is a renewed interest in getting as much low power LED kit fixed as possible.
The fault first came to our attention when the light began constantly flickering and had a ticking sound emanating from inside, regardless of what output levels we set it to. I have taken it apart and found that some of the electrolytic capacitors within the power supply had bulged and leaked.
After replacing the 3 x 35V 1000uF and 1 x 400V 120uF I now find myself in a position where all colour channels (red, green, blue, amber) work correctly at full output.
Once any colour (except red) is dimmed to around <40% of its full output the flicker returns and I hear ticking once again, albeit at a lower level this time.
It has been suggested to me that the issue lays somewhere in the feedback circuit on the secondary side. The replacement capacitors I have used are supposedly "low ESR" but as the issue is still present I am unsure what to investigate next.
Any help or links to further guidance would be appreciated.

Admittedly one of the capacitors has been soldered on a little wonky but the connection is good. I am aware this is a cheap and nasty power supply but unfortunately there is no money for a complete replacement and searches for circuit specs have been unsuccessful. I am tinkering with this as a hobby in an attempt to extend the light's lifetime.
Many thanks!


texts: How does an MCU detect current drop in an active-low button?

texts:
I'm confused as to how an active-low push button detects a change in voltage. Below is a model of a conventional setup of one of these buttons I found.

When the switch is open (like in the image), there is some current, I, flowing into the MCU.
But when the switch is closed, wouldn't the current just flow to both the GND and the MCU like in a parallel circuit? (because the electrons have the same amount of potential energy so the voltage is still the same?)
If so, how does the MCU detect when the button has been pressed if there is constantly current flowing into it?
I'm a novice with microcontrollers and electronics, so please don't hesitate to point out the obvious!
Thanks.


texts: How to Monitoring the lines between an Atmega8 and a LCD using Atmega32

texts:
I have a device that it use an Atmega8 to send some data to a 2*8 character LCD. the LCD has 8 pins and the pins are as below from left to right:

DB7 | DB6 | DB5 | DB4 | En(Clock) | RS | VDD | VFF

I think it is a HD44780 with DB0...3 , Contrast and WR connected to GND.

By the way, I want to monitor the lines between this LCD and Atmega8 using an Atmega32. I mean I want to achieve the data that transferring between them and send it to my computer's COM port and ....

I checked the datasheet of HDD44789 (A 2*16 LCD) and I found this :

Although this has 8 bit for data and mine has 4 bit, but I think both have a single procedure to print data on the LCD.

Now I want to know, how I can read the data on the lines using an Atmega32. for example can I connect En to  Interrupt-0 pin and in falling edge read DB4....7? Does it work?

And another question, when we send data to LCD in 4bit-packs, we send high nibble first or we send low nibble?


texts: Clarification on This Transformer Statement

texts:
Secondly, when the current starts to rise
  in the secondary wire, the magnetic field it
  generates is multiplied by the loop count.
  Obviously if we had lots of loops, a very
  small current will quickly generate enough
  magnetic field to cancel the inducing field
  out and there is no more force to raise the
  current. In other words: high voltage
  transformer will impose strong voltage on
  the secondary side, but this strength is
  quickly depleted.

This is a statement from this answer referring to why the current decreases in the secondary coil of a Transformer. The problem that I saw in this statement is that he said the induced current cancels out the magnetic field from the primary coil. Doesn't that mean there will be no more magnetic fields? And thus no more induction?


texts: What is the State of a MOSFET with a Constant Source Current and Floating Gate?

texts:
simulate this circuit – Schematic created using CircuitLab

Suppose we have a NMOS transistor, with and ideal current source (I_S) in its source. The drain is connected to V_DD, and the gate is just floating. It certainly cannot be cut-off since we have forced a current in its source, but is it triode or saturated? What if we change the MOS transistor to a BJT?


texts:
I'm finding a bit of a problem when trying to solve this question:

Show that the leakage current for the capacitor is given by
\$ I = \dfrac{Q}{KP} \$

where \$Q\$ is the charge on the plates, \$K\$ is the dielectric constant and \$P\$ is
the resistivity of the dielectric.

I know the concept behind the leakage current and why it happens, but I don't know how I can prove the equation.


texts:
I have a school project where I have to test a sensor and then measure the output with a multimeter.

I'm using a LM35DZ piece which gives as output itself a linear voltage of 10mV/C degree.

However, one requirement of this project is to have at the very ending a current between 4-20 mA.

The temperature in my hometown is about 25 degrees, so I'm willing to set my 0% (4mA) as 20 degrees, while 100 degrees would be my 20mA output. I've seen a couple of solutions involving transistors and potentiometers.

My rough set is receiving 5V at +Vs' leg of the LM35, GND grounded and the Vout goes directly to non-inverting input of a u741 operational amplifier, while I have a classical non-inverting amplification configuration.

The big deal here is I am struggling to transform this 0.2V into 4mA and further the 1V voltage into 20mA.

Any ideas/explanation attached (as I am also writing a report about it) of how to do it?

Appreaciate the attention and hope to hear something soon!


texts: How to interface with micro LCD projector?

texts:
I disassembled a cheap "wall projection" clock:

And removed the LCD board that displays the projected clock readout in front of the super bright red LED:

As a small hobby project, I'd like to wire this LCD up to a Wifi-equipped Arduino and make a simple NTP-based projection clock.

How do I interface with this board? I've never directly interfaced with an LCD before (with no accompanying control circuit), so I'm not sure how to proceed. As the image shows, the LCD board has two small ribbon cables containing 6 wires each. On each cable, one of the wires has white insulation. All 12 wires appear to go directly into the LCD pane, with no additional discrete components on the board.

The clock was powered by two AA batteries, so I'm assuming the logic level it uses is no more than 3V. The projected image displays the standard 4 clock digits in the format "24:59".

How do I apply voltages to these wires to display digits? Is it a simple one-to-one interface, where energizing one wire causes part of the display to turn opaque, or is it some sort of matrix, where multiple wires have to be activated in sequence to form the overall digits? Is it safe to assume the white wire is ground and the grey ones are signal, or is it the opposite?

Since I only have one of these, I don't want to blindly start experimenting by applying voltages across wires, and risk destroying it. How should I proceed?

Edit: I checked the output of some of the LCD pins from the clock's original control board and the patterns look very similar to the "multiplexed" example shown here. Each pin is outputting up to 4 logic levels. So I think I can safely assume it's a multiplexed LCD. Since I have 4 digits, does that mean there are 4 common/back plane pins? How would I generate 4 logic levels from an Arduino? Do I need to generate 4, or can I get by with two using the LCD driving method described here?

Edit: I'm pretty sure this is the output from one of the backplane pins, since it never changes, even after several hours. It looks like the pulse is 4ms wide, for a total "on" phase of 8ms, and the distance between repetitions is about 16ms. Based on the documentation for multiplexed LCD control signals, the pulses on the backplane pins can't overlap, meaning there's only enough room in the "off" phase for one other backplane signal. I think that implies there are only 2 backplane pins. Is this correct?


texts: Why Lm7905 give positive voltage instead negative in Lt-spice simulation at EasyEda software?

texts:
I have selected the Lm7905 and lm7909 in simulation mode in EasyEda software like this:

Which could be seen here:

https://easyeda.com/editor#mode=sim,id=|1f8d2e91e71e4daeba70b25b2bc15fa6|4b4839cf2c8c497b981f4f62a1a04f0a|310de4f753f3458f88e92d9f05ab0594

So as you could see the multi meters have the same 5V and don't show -5V or -9V?

Alternative link:

https://easyeda.com/forum/topic/Why-Lm7905-give-positive-voltage-instead-negative-in-Lt-spice-simulation-at-EasyEda-software-d9f1a389e39442f197064ccd155094f5
Thanks.


texts: MPLAB Mindi for SIMetrix/SIMPLIS simulation

texts:
I'm considering this tool as a replacement for SIMetrix/SIMPLIS for the simulation of DC-DC converter feedback loop response.
I would appreciate answers to questions as follows:

MPLAB Mindi seems free (as in beer), without limits in circuit size / complexity? (such as those imposed by SIMetrix/SIMPLIS Elements, that's the free flavour of SIMetrix/SIMPLIS). Is that correct?

Is the MPLAB Mindi's IDE in line to that of the "new generation" MPLAB? (I dislike that IDE).

How do these two compare in terms of usability? (I would like to know this from anyone who has used both.)

Do these two tools use the same file format for schematics?

I'd also appreciate any other words of advice from people who has used both of these tools.


texts: Can I purchase an MIT 6.270 kit anywhere? If not are there alternatives?

texts:
When I was in High School I used to work with the MIT 6.270 Robotics Kits in a Robotics class I both took and then later was a TA for. I loved those kits, they had an embedded controller you could program in C-code, and you built the robots using legos.

Is there anywhere I can purchase one of these boards? I see that I get one if I become a Gold supporter of the 6.270 but I don't have a spare $10,000 at the moment...


texts: How to have periodical repetition of customized pulse waveform in LT Spice?

texts: I have a customized Pulse pattern and I would like to have it in repetition. Does anyone know how we can establish that in LT spice?


texts: A question about PLC architecture and ladder logic

texts:
I guess a PLC is programmed and run by a micro-controller  at its centre.
But normally we use C language to program micro-controllers.

When we program PLC, is the ladder logic first converted to C or compiled directly by a special compiler?


texts: Voltage on a Transmission Line with Ideal Conductors

texts:
Let's consider a transmission line with Perfect Electric Conductors.

We know that if an external AC source is applied, we get a voltage waveform between the conductors which is function of the position (and also of time, but focus on the first dependence).

But we know that in a perfect electric conductor the electric field is orthogonal to its surface, and this means that its surface is equipotential. This property is true in any situation (steady state or not), because the tangential electric field is always 0 in a perfect electric conductor.

The following picture shows clearly that E is orthogonal to the conductors' surface.
enter link description here

But this seems in contrast with the fact that the voltage depends on the position.

Which is the solution?


texts: BLDC speed/torque control with L6229 or L6235

texts:
I'm trying to control 12V 12,000 rpm BLDC motor with 3x120° Hall sensors
using ST evaluation board based on L6229 IC.

I tried to control motor's speed by feeding PWM to FWD/REV pin as suggested in the design note.

When PWM = 0 motor spins in one direction at full speed, 255 - opposite direction full speed. Coming closer to PWM 128 - speed proportionally reduces till zero as expected, but TORQUE ALSO DROPS DRASTICALLY...

Also tried to feed different control voltages to Vref pin, but can't notice any differences in motor behavior.

I need constantly slow-down/speed-up motor's speed and keep acceptable torque on slow speeds (motor most of the time will work on 1/3 of top speed).

And BLDC motor in theory have bigger torque on slower rpms. But I can't achieve it. Maybe someone can help me wit this or recommend easy/cheap driver better suitable for this task?

L6229 datasheet:

And there is eval board schematics: :

And also attaching motor curves:


texts: Puzzling result from opamp circuit. Using opamp for negative reference

texts:
I've got a circuit using two dual opamp ICs and one voltage reference (see schematic below).  I have a dual supply and use one of the opamps to create a low noise negative reference.  The other opamp IC uses these two references.  I have a simple follower and a differential amplifier implemented in this second IC.

The problem is that the follower doesn't follow(??).  Any ideas about why this isn't working?  I'm pretty sure its not a wiring problem since its actually on a PCB created from the schematic below and I've checked it pretty thoroughly.

Edit:
A couple people noted some odd/wrong things with my schematic.  The image above is sub-circuit pulled from the one shown below.


texts: Efficiency Test of Permanent Magnet (PM) Motor With Variac&Fixed Resistance

texts:
We have a 3-phase permanent magnet motor and want to test its efficiency in generator mode.

We can give a mechanical input power with an external motor (torque meter and tachometer installed) and we also have an oscilloscope, a 3-phase balanced fixed resistance and a 3-phase variac (auto-transformer), so I was wondering if I can measure the efficiency of the motor by loading its output with variac&resistance.

Since the output of the motor will not be pure resistive because of the variac, do I have to consider the phase difference shift between the output voltage and current of the motor?

Or is this setup not proper for efficiency testing at all? Is pure resistive load necessary instead of an inductive load?

My oscilloscope can measure the phase-to-phase voltage and current, and output the active power as Watt (and I have to multiply it by square root of 3 for 3-phase power I think).


texts: Can I turn on a relay OUAZ-SS-105 from high on P26

texts:
Is it possible to turn on a relay  OUAZ-SS-105D using a high on pin 26. See image

Case 1: if I replace the P26 connection with a wire to vdd the led "GOES ON". The vdd voltage is 3.3 volts.

Case 2: if I apply a high to P26 (which reads as 3.3 volts as well) the led DOES "NOT" go  on.

What is the difference of the volts from the vdd or p26?


texts: How a multicore processor is initialized?

texts: Is there any general protocol or algorithm to start a multicore processor? If so, how it works?


texts: Can anyone explain this balanced driver circuit to me?

texts:
I'm looking to generate a differential signal to control a laser projector's galvos, and as I understand it needs to be +5V/-5V (10Vpp). I've found this circuit for a laser harp, but I'm confused about what this specific dual-opamp design does. It looks as if it's a pair of inverting and non-inverting amplifiers with a gain of 1, but they're being fed into each other. Here's a picture:

The original can be found here.

I'm curious if anyone could tell me what it's called, or how it works, because I've lookat at plenty of 'example circuits' and couldn't find anything that resembles it.


texts: Pluggable Cable for multiple analog connections

texts:
I have a device which comes in two parts; a microcontroller sits in one part; both parts have a matrix of wires; accordingly, I need to cycle power through several cables while reading the current/voltage output from several others.

As some of the wires sit in the part that does not contain a microcontroller, I need to be able to connect them in such a way that I can selectively cycle power to some of the wires and read the current/voltage output from several others; this cable must be pluggable (or at least easily assembled/disassembled) and support at least 15 independent connections.

I don't really have experience with EE; my first thought was to essentially "repurpose" a HDMI cable (since it has 19 pins), but I was told that you can't use it as an analog cable. If there's no reasonable way to do this as an analog connection, how would I go about using a digital connection?


texts:
It seems the best temperature stability I can get with conventional capacitors in the 330pF range are COG/NPO ceramics at 30ppm.

Are there any better technologies, or techniques I can use to compensate for capacitor drift?


texts: Strange behavior with a Microchip KSZ9031RNX after switching off and on

texts:
I use a Microchip KSZ9031RNX as Ethernet phy on a custom board. I have two boards of the same type. The KSZ9031RNX is connected to an TI Sitara AM5728 (ARM Cortex A15) microcontroller that runs embedded linux (Kernel Version 4.19.38). Now I'am facing the problem, that the phy sporadically doesn't work as expected.
For example on board one the Link LED is always on. Regardless of whether an Ethernet cable is plugged in or not. And it is impossible to get an Ethernet connection. The chip seems not working. On the second board the link LED switches on when plugging in a cable and the board connects to the Ethernet as expected. But sometimes after powering off and on the phy doesn't work. The LEDs stay off when plugging in the Ethernet cable and an Ethernet connection can not be established. After one or some more power on resets the chip works without any fault again.
I checked the hardware several times and couldn't find any faults. So I'm going to exclude the hardware for now.
After powering on an additional reset is performed by pulling down the phy's reset pin for a few milliseconds. So afterwards the phy should be in an well defined state.
The reset circuit looks like this.

What I'm doing wrong?
Are there probably some special timing requirements at power on? Or a special power on sequence that has to be satisfied?
Are there some special timing requirements at power on? Or a special power on sequence that has to be satisfied?


texts:
I would like to pump 4-5 A to a high-power LED for 100 µs. My system has only a 3.3 V battery, and this 100 µs high-power event takes place once every 10 seconds.

What is the best way of doing this without upsetting the batteries?

The answer below is very good. However, I am looking for a schematic I can use and test out.

More exact requirements:

Battery: Li-ion
Current 5 A
Pulse Duration: 100 µs
Pulse Rise time <100 ns
Minimum time between pulses 10 ms
Pulses are controlled with a 3.3 V I/O GPIO from a controller
The voltage drop across the LED is 3.5 V. Ideally I like to be able to put three or more in series (10.5 V voltage drop)
Datasheet to the LED

Bonus question

If you have a better LED recommendation with a large angle that is in the invisible range, please let me know.

I have implemented this project, and it works well except the leakage current. No matter what I tried, I couldn't get rid of the leakage. I tried a few types of opamps add a pull down resistor to the output of the opamp, etc. I end up turning off the opamp to cut the leakage. It works, but it is not very neat. I would be happy to hear what experts think of the situation.


texts:
I am working with ATxMega128 and programming it in C.

I have two inputs coming from a sensor and I want to turn on an LED when I get output from either of the sensor.

I can blink my LED if i get output from both of my sensor (i.e. I can do ANDING using &) but I do not know how to do ORRING. (Just need the syntax)

One way i can think of is to write two separate if statements taking one sensor at a time but I want to write a single if loop.

Can you please help me out?

Thanks.


texts:
I just ordered some 18650 batt and out of curiosity, I want to know the correct capacity of it.

I have an usb meter, which read the following:

Charge: 5.25V, 5683mAh
Discharge: 5.09V, 2927mAh

The batt was labeled at 3300mAh. The powerbank contains 2 batts.

So I want to ask:

The powerbank rated at 6600(3300x2)mAh @3.7V, mean rated 4884 mAh @5V. Is this correct?
So if 1 is correct then actually the batt is only ~2000 mAh@3.7V?
How to estimate the convertion rate of the powerbank?

Sorry if any noobie question, I'm totally new with this thing.


texts: Problem in temperature transmitter because of VFD (Variable Frequency Drive)

texts:
I made an amplifier of PT100 bridge which operates on 24V DC supply and gives 0 - 10V DC for 0 - 400°C when tuned. The circuit is as follows :

Here P2 + and P4 S+ are shorted and P4 S- is left open. PT100 is connected between P2 + and -.

The device works fine and gives proper output in my lab but it is to be used in an electrical control panel that has VFDs (Variable Frequency Drives). When the load is connected to the drives, the output of my amplifier turns 0. The weird part is if I connect a multimeter to measure the output, it gets to a value near the desired output but fluctuates. I put a 1M resistor across the output but it makes no difference.

The input power supply remains same as well as the input to the amplifier across P4 S- and P4 S+  remains very stable.

This might be the noise from the VFD harmonics causing this. I tried using shielded wire but no difference.

Is there a way to prevent the effect of noise on my amplifier. Some sort of a filter. Please suggest. Thanks for all the help in advance.

Also, I don't have access to the VFD. All I can do is modify the transmitter (Amplifier) and replace the existing one.


texts:
I want to count the pulses generated by Picoscope, my signal frequency is (20Hz)

I used the timer2, the problem is that the counter increment to 1 and came back to 0, I don't understand why ??? since it must increment every 50ms.

I devellopped the code show bellow :

 #include "stm32f4xx.h"
 #include "stm32f4xx_rcc.h"
 #include "stm32f4xx_gpio.h"
 #include "stm32f4xx_tim.h"

 void GPIO_Init_TM(void);

 int variable = 0;

 int main(void)
 {
  GPIO_Init_TM();
  while(1)
  {
    variable = TIM_GetCounter(TIM2);
  }
 }

 void GPIO_Init_TM(void)

 {

RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);

RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);

GPIO_InitTypeDef gpioStructure;
//TIM_TimeBaseInitTypeDef timerInitStructure;

gpioStructure.GPIO_Pin = GPIO_Pin_15 ;
gpioStructure.GPIO_Mode = GPIO_Mode_AF;
gpioStructure.GPIO_PuPd = GPIO_PuPd_UP;

GPIO_Init(GPIOA, &gpioStructure);

GPIO_PinAFConfig(GPIOA, GPIO_PinSource15, GPIO_AF_TIM2);

TIM_EncoderInterfaceConfig(TIM2, TIM_EncoderMode_TI1,TIM_ICPolarity_Rising, TIM_ICPolarity_Rising );
TIM_SetAutoreload (TIM2, 0xffff);

TIM_Cmd(TIM2, ENABLE);

}

and this is the result I get :


texts: The single-power-button logic of the cell phone

texts:
As known the cell phone has a single power button (most if not all), long press of it can power on the phone or choose to turn off the phone in the UI (my phone is Samsung). I wonder how is it implemented internal. Will the power button complete cut off the power supply from the battery? Or the phone never be cut off from the battery completely and there are some daemon code (like sleep or stand by mode of some MCU) to monitor the power button event?

Anyone has some clues\docs\links?


texts: Does it make sense to plot the angle in an signal spectrum analyzer?

texts:
I've built a toy oscilloscope with an Arduino, acquiring the samples with the ADC and plotting the spectrum on my computer. The spectrum is the output of the FFT algorithm. You can see a video here of the program in action.

The yellow line is the actual value of each sample as the output from the Arduino's ADC. The red line is the magnitude of each complex number as the output from the FFT function, and the green plot is the angle of each of those complex numbers. The first spike is noise from the AC main power line, which is 50 Hz.

The red plot shows the "energy" of each frequency. What information does the angle shows? Is there an intuitive explanation?


texts: How do I measure the error of my ohmmeter

texts: I have to do an Ohmimetro to a college assignment, but I don't know how discover the measure error of my circuit. When we buy a multimeter, the equipment has a measure error calculated by the manufacturer, how do they calculate it?


texts: Does anyone have any experience spec'ing power supplies to CEC level 5? And if so what is the maximum cable length allowed? I can't seem to find the relevant resources for on this subject matter


texts:
I have seen this picture in a number of the Atmel datasheets. This one is from the ATTiny48/88 datasheet.

Can someone explain in some detail how to properly implement this on a 2-layer board? I have to imagine that the Analog Ground plane has to be connected to the digital ground plane somehow on the PCB, or does that happen internally in the AVR? Is the dashed line meant to be taken literally in terms of the shape and extents of the Analog Ground plane (there are no dimensions on the diagram, so I doubt it)?


texts: Why is bi-directional current sensing required in sensorless BLDC field-oriented-control?

texts:
For the past few weeks I've been trying to understand Field-oriented-control for 3-phase motors. Eventually I would like to implement one. I've gone through dozens of application notes from Microchip, Atmel, TI and ST. Unfortunately I'm having some trouble understanding the phase current measurement requirements.

As you know for FOC we need to know all 3 phase currents (lets call them I_A, I_B and I_C). Since according to Kirchhoff’s law (I_A + I_B + I_C = 0) we can get away with measuring just 2 phase currents and calculating the remaining one. Most application notes use 2 low side current shunt resistors to measure the phase current I_A and I_B.

My question is that every application note that I've seen states that it is important to be able to measure the voltage difference across the shunt resistor both as a positive and negative value (I assume because the current in the each phase can have two directions). To do this they recommend to add a 1.65V offset to the current measuring op-amp (assuming a 0-3.3V ADC range).

However when I try to visualize the current path in the 3-phase inverter I only see current flowing through the shunt resistor in one direction. Please look at the images I made to illustrate my point.

As you can see, regardless of the phase current direction, the current flowing through the shunt resistor is the same. We can then infer the direction of the phase current by looking at the inverter configuration at that that particular sampling instant.

Furthermore, I've only seen low side current measurement in FOC application. Recently I came across the BTN8982 half-bridge IC from Infineon. This device includes a high side current mirror (which outputs a current proportional to the current through high side mosfet). As such it can only sense currents uni-directionally. Can this device be used for FOC applications?

Thank you!


texts: How do electrons flow in a closed circuit?

texts: So basically I was doing a presentation on batteries and how they work to power a connected device such as a bulb or a torch. While researching this question popped up in my mind. The electrons flow in the external circuit, why and how?


texts: Analog 3-state buffer where the input voltage equals the output voltage and is controlled by a digital control line

texts:
I'm looking for a device that can control an analog signal without interference. I need it to be controlled by a digital control line (0v - 5v). The input voltage (0v - 5v) should equal the output voltage (0v - 5v). It doesn't matter if the control line is active high or active low. If the control line is active then the output should equal 0v.

An example application might be as shown below. You have a blinking LED but you also want to control the brightness of the LED using a pot.

simulate this circuit – Schematic created using CircuitLab


texts: 15v from 20pin and/or 24pin ATX Power Supply. Connecting PSU circuits in series

texts:
I have a portable 12v car battery charger, jumper, maintainer, and inverter with integrated USB ports, 12v car adapter slot, jumper clamps, emergency LED light, and a 3 prong 110v/60hz wall outlet. It is charged by a 15vDC input using a common cylindrical DC plug. I have a male connection that fits and is capable of supporting the current drawn by the unit. I however do not have an AC/DC conversion box for 15v.
I have USB ports but I have heard that you CANNOT chain USBs in series. I also have several desktop PSUs with 20/24 pin ATX, 6 pin PCIe, 4 pin IDE, 2 pin CPU, and SATA connections.
My question is, using the available connections, can +15v DC be achieved? If USB can be used in series, how? If not, can I use the PSUs?
I have 4 units to work with, one being 20 pin and 3 being 24 pin. I think Ihave 2 possible options using the PSUs. Wire 5v in series to get 15v. Would 3 PSUs be needed? I dont fully understand how the circuits connect internally. Would this simply be a matter of: GND|+5v -> GND|+10v -> GND|15v?
Alternatively I could use 9 sources of 3.3v in series to make 29.7v. I could then halve the voltage to make 14.85v. I am still unsure of the internal workings of a PSU, furthermore i do not know how to divide the voltage of a DV circuit. (probably my next google search)
I can also acquire if needed 19.5v and 9v adapters
Please forgive me for any errors. I would be happy to correct any issues in this post. I mean only to improve upon available content and enrich the community.


texts: What resistor is needed to regulate the current through 2 3V LEDs in series with a 9V battery?

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So I'm trying to power 2 of these LED lights together in series. I know that I have to add the voltage of the two lights together and get a resistor that restricts the power to that level. I have a 9V battery and the lights are 3V each. I brand new to all of this, and understand almost nothing, so any help would be appreciated. Can someone help me choose the correct resistor (And how to identify that resistor with the color branding thing) so two of those lights listed above can be wired in series?
Thanks!


texts: How can I multiplex LEDs using PIC16F1768 mcu and MCP23S17

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22 LEDs will use in a project as a display, where 11 will use to show the brightness and rest will use for color. For thar MCP23S17 I/O expander is used along with PIC16F1768(QFN) microcontroller. MCU GPIO connecting with two PNP transistors (BC857)  which will be used for multiplexing(one for Brightness and another for Color)
Each Led works at 3V forward voltage and 5 mA forward current.
Need design guide
1.I was thing to configure the GPIOs as open drain with external pull up resistor. (what can be suggested pull up resistor value). Is it possible to use internal pull up?
2.What will be R1,R2, R3 values to get 5mA?
3. What will be the GPIO pin output voltage when while pull up?
NB: any figure or calculation for explanation will be very helpful
Please see attachment


texts: Measuring the power output of a hand-crank generator

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I am working on a project which aims to compare the energy generated from a hand-crank, DC generator, to that of solar panels.  The hand crank generator will not actually be powering anything, but we need to get an accurate measurement of power from it.  This may be a flawed approach, but our thinking was to hook it up to a resistor and measure the power using and Arduino and the formula P = (V^2)/R (implementing a voltage divider if necessary to prevent overloading the Arduino).  However, the power will change depending on the size of the resistor, so we are worried this will not give an accurate measurement.  Forgive me if this is a naive question, but any help would be greatly appreciated.

Thank you!


texts: car Ignition switch relay maintain closed after remove power

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I have a car ignition switch that has 4 settings and is +12v DC:

0=off (no voltage)
1=accessory (only some items have power) (no voltage will go to pump)
2=on (all items have power)
3=start (momentary switch for start power)

I have a pump I want to wire up in the following way:

When the switch is on 3 (momentary), the pump gets power and turns on.
The same switch then moves to setting 2, where the pump remains on.
If the switch is turned to positions 0 or 1, the pump turns off and
will remain off until the switch is returned to position 3

(the pump    will NOT turn on in position 2 alone, but will remain on
in position    2 AFTER position 3 has activated the pump).

I believe this can be achieved with two SPST relays, but can't seem to figure out how to do so.
Is this a good way of doing it:


texts: Oscillation of the Drain-Source voltage in flyback converter

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The image below describes a flyback converter with a clamping circuit off and the leakage inductor is reset, so the clamping diode is off (blocking):

My question is about the resonant frequency.
The title of the image and the formula given in this page for the frequency of the oscillation includes only the leakage inductance and the lump capacitor. what about the primary inductance, why does not this inductance contribute in the frequency of oscillation of the drain voltage at this moment?