texts: Is the transformer leakage inductance increasing or decreasing VS. size

texts:
I have built an sine filter for a small inverter that feeds a transformer 250VA. The filter is basically a LC filter, that uses leakage inductance of the transformer with a capacitor connected in parallel to the secondary with a small value damping resistor.

I did use the function generator and scope to tune the resonating frequency so that  is below switching frequency of the inverter and higher than highest possible fundamental output frequency. But this was tight tune: \$F_{SW}=8kHz, \ \ F_{OUT_{max}}=400Hz\$

Now they simply changed the inverter and the transformer with more powerful one. Now I would like to ask what should I expect:

the leakage inductance has increased, since the transformer is bigger?
the leakage inductance has decreased? Logical assumption is that big transformer has very low leakage inductance, compared to small one, because otherwise they would fail to supply the powerline.

simulate this circuit – Schematic created using CircuitLab


texts: Operational Amplifier (UA741) clipping well under voltage rails asymmetrically EDIT: had same issue with different opamp

texts:
EDIT 2: I should point out we were having the exact same problem with a OPA2134PA.

EDIT: Problem persists up to +-30V and adding parallel resistors to the virtual ground capacitors did not help either.

Been trying to figure out what looks like a clipping issue in the linked circuit.

Our input is a 8kHZ 120mV sine voltage signal coming from an AD9850 we are trying to amplify it to a 5V signal. The signal is clipping at 1.3 V PtP well below our rails of +-5V.

We've upped the supply to 20V (+-10V) but the "clipping" remains (the clipped signal peak to peak slightly increases to 1.8ishV). We have a slightly uneven splitting for the supply voltage on the OpAmp at 5.5V and -4.5V at a 10 volt supply but from what I read that should not be causing that much of an issue?

The negative peak is clipped less than the positive peak. We are pretty sure our capacitors are oriented correctly (we have C1 + facing the positive side of the supply, C2+ facing the ground and the C3 positive facing the AC input.

simulate this circuit – Schematic created using CircuitLab


texts: TP4056 charge enable and battery detection

texts:
Does pulling down the TP4056 CE pin to low disables the entire chip or just stops charging?
Also is the CHRG pin flashing when battery is not connected?
How can we connect the CHRG pin and the STDBY pin to the micro controller to detect if battery is connected or not?


texts: Latching switch, momentary pulse output when switching on

texts:
I'm really struggling to find a simple circuit that'll give me a pulse (~1s) when switching the circuit on. The latching switch can't be changed and already controls other circuits, and the new module/controller requires a short pulse to turn on, but will reset if the on control input stays on for more than 10s.

Edit to add more info - Voltage when latching switch is on is 12V and 0V when off, there can be a constant 12V feed if needed to power circuitry but this'd just be pulled from the back of the switch. The new module requires a ~1s high (12v) pulse to tell it to turn on. Much less than that and it misses the on command sometimes.

I'll see if I can get a schematic to upload later as can't at the moment

Edit to add more info: pulse current - no more than 50mA. The reset time could be as low as ~200ms in theory but if it's a limitation ~1s would be acceptable

I'm not 100% sure but I believe that as long as the pulse is at least 9v it should work


texts: Grounding Ignition Coil Using IGBT ckt....Not Working + Can't Understand?

texts:
I am a hobbyst, and recently been working on a small project of my own,
Creating a rev limiter of my own.
Following is my circuit which will explain a lot about what I am trying to do.

First of all following part of the ckt is original:
+12v,To Vehicle's Trigger,spark plug;Transformer/Ignition Coil
Rest is DIY
There have been few problems I've encoutered and need help with :

As soon as I connect the collector @ c and emmitter to GND(Vehicle's battery -ve terminal), the engine halts(or bike won't start), ( even when the gate is pulled down )

--> Multimeter Probe Red on Ground and Black on E ( while DIY ckt is not grounded ) showed a +0.18 volts
ie: ground is positive while E is negative !!!  WHY ??
--> I figured out that when I dissconect 1N5408, and the ckt when connected to GND and @ C to primary side of ignition coil It won't halt the bike
but also then the gate won't open (applying 12 volts from battery +ve)
ie: Closed gate works fine but open gate won't shut the bike off, ie: the gate won't open !?

I've read about inductive loads, as soon as vehicle's trigger switch opens there will be oppossing voltage ie: highly +ve @ C (hence 4.7uf capacitor acts as IGBT protector while .1uf cap prevents accidental gate opening since gate-collector absorb some charge on their own (same with gate-emmiter)) so the current shall flow from C to E, but because of diode I noticed current is flowing oppossite, hence the bike is halting even when the gate is closed.

Observations :
"Ignition Coil socket" when dissconnected and (socket being measured) measured using voltmeter shows +ve and -ve(black wire) as shown in picture.
Only 2 wires @ ignition coil primary side socket, so I figured out the trigger is integrated with ECU.
Also the Ignition coil measured 2-2.5 ohms.
Ignition Cut diy is a signal, for testing purpose I am using +12 volts from battery's +ve terminal
IGBT is 25N120A
https://www.electronicscomp.com/fga25n120antd-1200v-25a-npt-trench-igbt?search=25N
Also, I've tried the above ckt with inductive load (Toy Car Motor) works just fine.
Need Help..


texts:
I am interested in using an ESP8266 to power a physical interface for a network connected device. The device itself supports REST commands, but I am not quite sure how to send PUT requests from the ESP8266. Right now, I am able to use the device's web debugging interface to send REST commands, but I am not sure how I would translate that to the ESP8266.

Using a web browser, I am able to GET information by browsing to

<DEVICE_IP>/API/<USER_ID>/<RESOURCE>

but I can only get the current state of that resource by navigating to that URL. How would I send a PUT request?


texts:
I'm experimenting with an eink panel (ED060SC4), powered by a TPS65185EVM.
It's all working well exept when i'm done updating the panel image and I have shutdown the power chip, there is still some lingerring voltage (between 20 and 160 mV) on randomely some of the 4 main power lines (+22V, -20V, +15V, -15V).
The problem is this small voltages cause the panel image to slowly fade toward grey (quickly in the first few seconds then more slowly).
I blame it on the capacitors that are on those power lines but as I'm stuck using this power board for various reason, I'm looking into a way to cut off the power lines when i'm not using them.

I was thinking of using transistors as switch to cut those power lines junction when not in use but i'm afraid it will reduce the voltage arriving to the pannel, possibly impeding it's working and also that some small voltage may still pass through it when "closed".

I also thought of using relays but the noise they emit will be a nuisance in this project.

Have you any recommandation in the matter ?


texts: Does VHDL permit "alias" for procedures in packages like we can use them for "external signasl"?

texts:
If procedures with same name and signature exist in multiple packages, the tool might not know which to call and simulation and/or synthesis shall fail. One way to resolve this conflict is to give the entire "path" to the procedure by using the library name followed by package name followed by procedure name.

In theory a better way in which this can be resolved is if we can assign alias for procedures e.g if multiple packages have the function print(...), rather than say "lib_a.pkg_a.print(...)" we can just define an alias like alias "lib_a_print is lib_a.pkg_a.print(...)".

How can one assign alias for procedures inside the VHDL?


texts: If I can name 3.3 kilo-ohm resistor as 3k3, then can I name 4.7 micro farad capacitor as 4μ7 in my schematic notations?


texts: How is 'specific' data found and taken from a Semiconductor Memory Source?

texts:
In a semiconductor memory chip, each bit of binary data is stored in a tiny circuit called a memory cell consisting of one to several transistors. Volatile type.

Suppose an application stored its data in a particular segment on the computers RAM.

How would the CPU know what data to extract and how would it sort through the other data to get to it. If everything in its core level is 0 or 1 its hard to distinguish what purpose 'x' memory has.


texts: How can I amplify 868MHz transmission done with a wire antenna?

texts:
My garage door is sending its status to a control device we have in the house. This signal is not always received by the control unit so it wrongly shows the garage door is open when it's closed. The garage door electronics has a wire as antenna soldered directly on the circuit board and uses 868,30 MHz AM to transmit.

I asked about this here (Are the same type of antennas used for receiving and transmitting?) but that discussion was about antennas.

Now I would like to know if I can use an amplifier like this LNA 0.1-4000MHz gain 20dB Noise LNA RF wideband amplifier Module HF VHF / UHF to amplify the transmission.

I would replace the wire antenna with a short shielded wire, attach it to the amplifier and then put the wire antenna after the amplifier. Does this make sense and would the above amplifier?


texts: How to use 2 TSOP1738 (infrared sensor) in one circuit?

texts:
Attached picture shows my circuit. In it I use only one IR sensor (TSOP1738) but now I want to add another IR sensor (TSOP1738) to my circuit. So my questions are:
1. Is it possible?
2. How (parallel or series)?
Thanks.


texts: Configuration of load cell on digital scaling

texts:
UPDATED!
Anyone can tell me how to configure the load cell (like mine is MLC902) on digital scale? How is the calculation voltage output when is loaded by 50kg or 100kg?

![this is my wheatstone bridge][2]

Updated :
the second schematics is my wheatstone bridge with 4 load cell. The load cell have 3 wires, red, white(green) and black. R1(red wires), b1(black wires) and w1(white wires) on first load cell. R2(red wires), b3(black wires) and w3(white wires) on second load cell. R3(red wires), b3(black wires) and g3(green wires) on third load cell. R4(red wires), b4(black wires) and g4(green wires) on forth load cell.
i know little bit about wheatstone bridge, just like to calculate the output Vo= R1/(R1+R4) VB - R2/(R2+R3) VB. But the wheatstone bridge have 4 load cell on each side, which is have a spesification output voltage 1,15mV/V and resistance 1K for each strain gauge on MLC902. Anyone can help me? or give me some reference?


texts: Options for short range distance determination between two objects

texts:
I have a project idea in mind, but it involves calculating the distance between two people. I've looked into Bluetooth, RFID, and NFC (unsure about this one), but none appear to offer the accuracy I would need (I am a novice at best, so I would welcome being corrected on this).

Bluetooth: seems to only be able to detect that someone is either in range or not in range. And although that range works well for what I want to do (~30 feet is common?), I would ideally be able to specify distances within that range at 5 foot intervals.

RFID: seems to only work with very short (sub-meter) distances.

NFC: Unsure

Would one of these options work, or are there others that could work? Or is GPS the only route?

UPDATE: The idea is a child safety "net". A child would have some kind of beacon on them that only needs to send out a signal, and then the receiver would be on the parent. That way, if the child moved more than x distance away from the parent, the parent would be notified.

Ideally the parent would be able to set a different allowable distance depending on the environment they were in (crowded city street - small radius, park - large radius).


texts: Reading the frequency of an AC signal using an arduino

texts: Basically I have a motor with a magnet spinning on the end. I have a sensor that produces an AC signal when the spinning magnet is placed next to it. It produces a voltage of ±300mV. I want to measure the frequency of the signals, so I can calculate the speed of the motor. I want this to be fed back/processed to an arduino so I can display the reading on a screen. Is there a simple way of doing this?


texts: Voltage Generator with Full Wave Rectifier

texts:
I have simulated a circuit which gives +12V and -12VDC output. I am planning to obtain input signals from a transformer. I have some questions related to it, if you share your ideas i will be very happy. I used LM7812, LM7912 regulators and S1M diodes.

There is a delay at the beginning of the output2 signal (-12V). What can be the reason of it? Is simulation the reason of this delay or will it still there when the cirucit is set in real life? How can this be prevented? I intend to use this negative supply for SN75188 VCC- pin. Can this delay affect IC's operating?
If a special IC like MAX764 is used, does this delay still happen?

This is my circuit;

Output Voltage Signals:

Output Current Signals (Reversed because of LTSpice's display of current, both signals should be inverted):


texts: power absorbed in an inductor in an RL circuit during step response

texts:
strong text
In the following circuit , what I found was that , the current through the circuit reaches a steady state after some time .

but , then when I plotted the power through the inductor VS time in pspice , I found that the power increases , and after some time , starts to decrease .

My question is , if the current through the inductor reaches a steady value , then how come power through the inductor first increases , and then decreases ?


texts: Single Ended Precision Variable Amplitude Square Waves and Charge Injection

texts:
I love to hear any thoughts about a good break-before-make analog switch with low charge injection or even even better any thoughts on generating precision amplitude square waves in general.  As to why ...

I have a 5V±5%/GND powered op amp (AD8648), a precision 2.5V(±0.2%) low impedance voltage, and an external 3.3V±5%/GND clock input that runs at about 10 KHz.  I need to generate precision amplitude 10 KHz square waves that are symmetric about 2.5V.  The amplitude will be controlled with a 10K digital potentiometer.  The potentiometer resistance is known with 0.1% precision.  The circuit needs to be as low cost as possible.  Ideally, I need a precision of about 1mv for an amplitude of up to 2.5V±~1V.  The resolution is not an issue as much as the precision.  I plan to use the AD8528 64 tap potentiometer, since it comes calibrated with the 0.1% accurate full scale value stored in internal memory.

One possibility that I am considering is to scale the voltage across a precision 1V reference with the potentiometer and then use analog switches to switch a capacitor above and below the 2.5V common mode voltage.  I have been looking at various analog switch possibilities and the best seems to be the LTC6943 switched capacitor controller, but it costs about $7 a pop.  I could potentially use other analog switches, but I am worried about the voltage offset you can get from charge injection from a switch not made specifically to balance it out, like the LTC6943.

Below is the modified LTC6943 voltage inverter application circuit.  It uses an inverting and non-inverting version of this circuit to drive the op amp input above and below the 2.5V reference by Vin, which will come from a digital pot divided version of the 1V reference.

So, to repeat the question, any thoughts about a good break-before-make analog switch with low charge injection or even any thoughts on generating precision amplitude square waves in general?


texts: How to map custom IP to the output pin on FPGA

texts:
I have a custom IP created with 2 output pin (en1_out and dir1_out)

May I know how to map these two pin to the PMod pin on FPGA (pin Y11 and pin AA11)? I have tried to open the elaborate design and in the I/O Ports I can't find these two pin.

I am using ZedBoard and Vivado 2016.1
Thank you!


texts: I've been seeing this term in many of the homework problems for circuits but there weren't any definition given for it in the book nor wiki. My assumption is that it relates to Vpp but I want to be certain. I would really appreciate it if someone could explain what it means.


texts: Possible failure reasons of a PMOS which is driving an inductive load

texts:
We have a product that has a vibration motor to warn users in some situations. In the legacy version of this board, following scheme has been used.

After production, some of those products are vibrating continuously or not vibrating at all. When we put multimeter in diode mode and measure between gate and source, we observe that it conducts in both ways.
Possible reasons of the failure might be:

Exceeding Drain-Source breakdown voltage which is -20V for IRLML6302 (We observed drain-source voltage using an oscilloscope when an healty device was vibrating. It was nowhere close -20V.)

Exceeding Gate-Source breakdown voltage which is +-12V (We didn't observe this happening either)

Exceeding continuous (-0.54A) or pulsed source current (-4.9A) (We checked the continous current but couldn't check for pulsed.)

ESD

Faulty part

Can battery - motor inductance or high Rds value (Due to not getting MOSFET into saturation region) somehow lead MOSFET to failure? What might be other reasons for this? Is there any obvious problems with this scheme?
By the way the logic level is 3.3V, the motor is similiar to used ones in mobile phones and we do not allow battery level to drop below 3.4V in the firmware. This problem occurs in approximately %15 of the produced devices.


texts: repairing damage: what size ceramic bypass capacitor

texts:
Repairing a motor control board from a washing machine.  A 1206 ceramic cap was burned up, there's a bulk electrolytic in parallel, rated 200v 1000uF.  I've attached the example schematic for the ic (IRDAKO726350B) and circled the area in question.  Replace with typical 100nF?  Is there a downside to putting in a 1uF?  I have ceramic caps rated to 500v.

datasheet link: https://datasheet.octopart.com/IRDAKO726350B-Infineon-datasheet-82521255.pdf


texts: Currently I try to use the STM32L0 microcontroller series. I found that ST offers a low-level C program collection called STM32SnippetsL0 too, parallel with their complex STM32CubeMX based HAL API. Unfortunately I can not use the codes under GNU/Linux because it supports only EWARM and MDK-ARM toolchains. Are there any possibilities to run this code with the GCC ARM Embedded toolchain?


texts: Microcontroller requirements for TFT display

texts:
I want to know if I can drive this 320x240 TFT display:
http://www.buydisplay.com/download/manual/ER-TFT032-2_Datasheet.pdf

Which has this controller built-in with 168KB dedicated RAM:
http://www.buydisplay.com/download/ic/ILI9320.pdf

Without having to use an expensive Micro with a dedicated LTDC chip.

but this is my first project using a nice looking display (not just alphanumeric) and I'm not entirely sure how to choose the Microcontroller for it and whether I need a particular one that has an LTDC. I want to display basic menus and don't need fancy animations, but I want it to look professional with minimal flicker and quickly refreshed screens when the menu changes. Any idea what the memory requirement/Clock speed on the MCU would be needed for a project like this?

Thanks for any help!


texts: Desig considerations for a 10k va inverter

texts:
I want to design a 10kva dc-ac inverter. I have some experience with low power inverters, and I assume the working principles are similar, so I need to know if there are any considerations when it comes to high power design. In particular, is changing power MOSFETs and the transformer power rating enough? Or do I need to switch to a completely new design and use IGBTs instead of MOSFETs?

As an example, take a look at the following from TI "800VA Pure Sine Wave Inverter's Reference Design - TI". Can I just change the MOSFETs to CSD18536KTT and use higher power transformers to change the design to a 10kva one?


texts: Interrupt within an interrupt on a PIC18

texts:
I am working on code for an external interrupt from RB0 on a PIC18F4550. When an interrupt is detected on RB0, timer0 is activated.

I then need to watch for timer0 overflowing. If it does, then the code can return to main. If it does not, this means another rising edge has been detected on RB0. Once I have a certain number of concurrent RB0 interrupts before the timer overflows, I move on to the next procedure.

I am new to interrupts and am not sure if 'dealing with' the interrupt from timer0 within my RB0 ISR is OK.

Do I need a new ISR for timer0 to be called from within the RB0 ISR?

Or is it OK to do as I am in my code?


texts: I am studying ARM Architecture and there is a slide which I didn't understand and can't find anywhere on the internet (Google, YouTube) - I've also looked for ARM homepage but they don't display any diagram. The slide is about the memory system for ARM. I would appreciate if someone could help me understand how it works or at least where I should check online to find this information. Specially I ask what are m and n Thank you.


texts:
I have a small (50mm x 30 x 12) battery-powered device to which I want to add a charging connector. I've been looking at panel mounted connectors such as this https://www.mouser.co.uk/ProductDetail/Switchcraft/PCL722AS?qs=fbkhFuCHoTZJW37LWjLsMA==, but curious if there aren't any better solutions for this. Current is relatively low (200 mA). USB seems like another good choice, but I am struggling to find one that can be panel mounted and sit relatively flush against the surface.

Thanks!


texts: Please help me to calculate the value of resistor R1 so that the current through R2 was 100uA. The only thing I noticed is that the output current is pretty much sensitive to changes of saturation current Is of both diode and transistor.


texts: What do I need to put my code onto a microcontroller?

texts:
I learned about coding a controller, but never actually put the code on the physical device. I am trying to figure out what I need to order to start developing a basic embedded system.

For example, if I have a PIC18F1330, I have MPLAB IDE and XC8 compiler. Great, so I have the code compiled, and I'm ready to put this on the controller. What do I need to have to have to transfer my compiled code on my PC, onto the controller?

I've seen things like an in-circuit debugger, and a PIC kit. I'm just lost at this point.


texts:
Does anyone have a circuit that will trigger a strobe light to flash in response to a TTL logic signal? Specifically, if I have a strobe circuit capable of flashing 1000 times per second, it seems like it should be possible, under logic control, to get pairs of flashes at say, 5 msec apart, with the pairs separated by much longer intervals, e.g., 100 msec.

Most strobe circuits I've seen use some kind of relaxation oscillator to periodically trigger the flash tube. These are fine if all you want are single flashes at a not-too-specific rate.

I know there are camera flash units that will flash in response to a switch closure, but these don't usually recharge fast enough to put two flashes together in the space of 10msec or less.

My hunch is that if I dump the charge from a small cap into the primary of a trigger transformer, through a switching device of some kind, the tube can be made to flash. The problem is dumping the cap charge quickly enough to get the trigger spike, and not toast the semiconductor with the backlash from the transformer input.

The other concern is that since the trigger circuit basically produces nasty voltage spikes, how to go about isolating the control logic from the spikes.


texts:
I need to measure current through a microcontroller at high side, with about ~1 µA resolution, ranging from 1µA to 25mA. The result is sampled by a microcontroller and sent to a computer or an on board display. The sampling speed I need is about 500kHz.

The problem I am facing is that the linearity of the gain when the current drawn is in the one digit µA area is quite unlinear. Say my amplifier circuit (consisting of simple op-amps) has an amplification of 800, the actual amplification is around 1000 at 1-3µA, and closer to 800 at 9-10µA.

I guess this is due to the power drawn by the operational amplifiers themselves in some way, so I tried to preamplify the signal with LTC6102 first and then feed this into my opamp circuits (one circuit per range of current), but still I struggle with non linear amplification even from the LTC circuit.

I have been in contact with Linear, and they propose a buck boost converter with integrated coloumb counter, but this is I2C and cannot give me the speed I need for sampling.

Are there any examples of circuits that can actually measure these tiny currents while still maintaining the sampling speed? I don't have the schematics right now, but can provide later. I just had to ask right away cause I cannot get this problem out of my head.


texts:
I was studying op amp application and saw the square wave, triangular wave, sine wave. I was wondering if it is possible to generate Gaussian shape wave with op amp. I am basically trying to modulate sine wave signal and Gaussian wave signal and send it to a short range pcb antenna. I am a bit newbie in signal processing so pardon me if I ask any silly question.
If Gaussian wave generation is not possible with op amp, Can anyone just suggest me about Gaussian waveform generation?


texts: Can I use Dupont wires for power delivery?

texts:
For a small hobby project I'm trying to control an LED strip from a phone. To prototype this, I will simply use a breadboard.
I have an external 12V power supply and the strip will use at most, 1.5 amperes.
My question is, can I use those cheap Dupont wires with the 2.54mm connectors to deliver power to the power supply?


texts: How does a residential grid-tied solar system work exactly?

texts:
Ok.. so I know how solar panels are connected to a combiner box & tied into a charge controller/inverter.  I also know that the AC from the inverter must be in phase with the line/mains power.

What I would like to know is the following:

Exactly how much voltage (above the line voltage) must the inverter output be in order to cause current to flow out to the grid?
On a 100A mains line, how much current could be output to the grid (assuming your solar array had slightly more net capacity than your line is capable of carrying & what would happen to the excess power from your solar system if it could not be sent out to the grid, due to it being higher than the mains line is rated to carry?
What would be the difference in an oscilloscope trace if I viewed the output from the solar system when it is grid-tied vs the normal mains trace on the oscilloscope if the grid-tie was not connected?


texts: Why are low-dropout (LDO) voltage regulators unstable?

texts: LDO regulators based on P-type transistors seem to be the preferred form of linear voltage regulator today, but I keep hearing about how I have to choose the output capacitor(s) carefully to guarantee stability. The older high-dropout regulators with N-type transistors didn't seem to have this problem. What is it that causes LDOs to be less stable? Is it the P-type transistor? The smaller difference between \$V_{in}\$ and \$V_{out}\$? Both? Or something else altogether? And why is the ESR of the output capacitor so important?


texts:
How hot can a lithium ion battery safely get while charging?  I've found some references to 113F, but I know a lot of batteries used in cell phones get a lot hotter than 113F.  I measured 140F on my Galaxy S4 while it was charging up from a fully discharged battery.  On the other hand, Samsung is currently exploding batteries with their Note 7, so cell phone manufactures may not be the best reference.

Is 113F the max ambient temperature for charging lithium ion batteries?  In that case, what's the recommended max temperature for a battery pack itself?


texts: What does the m symbol for magnetic flux mean? Why is it needed when the phi symbol exists?

texts:
For reference, I have read the Textbook of Electrical Technology by Theraja and I don't understand how it just uses the mass symbol as a symbol of magnetic flux in poles. Why is it any different from the original phi symbol? Why does the pole thing matter? Isn't it already covered by the magnetic flux quantity itself.
I don't have convenience right now of using a computer to just copy the parts from the book which I am confused with so I cited the reference. Another question I have is why do some formulas use the phi symbol while the others use the m? Are they different in terms of units somehow? Thank you.

Edit: Chapter 6, page 257 onwards. The m thing are on the first parts.


texts: MOSFET connection within oscillating circuit

texts:
I'm working on a group project, where for one part of the circuitry we have a "Royer Oscillator", which can be turned on/off via an N-channel MOSFET (IRFU4105ZPBF) at the input (whose gate is connected to an Arduino). The second part of the circuitry (not included in the image below), is essentially the filtering stage where we filter out desired frequencies.

The problem I'm having with this implementation is the MOSFET configuration (top left, disregard the diode), where the drain is connected to the supply, and the source is connected to the load (the rest of the circuit), however I'm not sure if this is the right configuration since when we build the circuit, it doesn't work (the MOSFET wouldn't turn on), and even the simulation has next to no current at the source, which leads me to think that it should be connected to ground, and the drain going from the Power Supply -> to the rest of the circuit?

Essentially my questions are:

Why am I getting next to no current at the source?
Is the MOSFET connected properly?
Can I have the drain connected to the supply, then have it connected to the rest of the circuit?

The individual MOSFET works by itself in turning on an LED, with the source to ground, and the supply coming through a resistor -> LED -> drain.

Most MOSFET circuits I've come across have the source going to ground, with the load coming from the drain, though I have come across others with my configuration below, so I'm unsure which is the correct one?


texts: Is there an intuitive reason for why NAND gate is a universal gate?

texts:
Now I know the maths and logic to figure out that every boolean function can be expressed using only AND and NOT gates, which in turn can be expressed using only NAND gate and hence every boolean function can be expressed using only combination of NANDs. I know the math, I can easily work out the how.

But, I am looking for a more intuitive (not necessarily non-mathematical, maybe philosophical) reason as to why this has to be true (if there is such a reason at all). For some reason I think that it is not just a mathematical fact that NAND gate is universal, there must be a more "deeper" reason or something in property of NAND gates that has this, if I am able to explain myself.

So, is there really such a reason? Or is the universal nature of NANDs really just a mathematical artificact just discovered by us somehow?

EDIT : Fixed the basic gates. I messed up that.


texts: How much mechanical energy (power) is converted to electrical energy (power) to have output voltage (no load connected)?

texts:
greeting .

How much mechanical energy (power) is converted to electrical potential to have output voltage (no load connected)?


texts:
How many transistors are in common uC, like Atmega (AVR), Cortex-M (ARM), Cortex-A (ARM, or mobile processors in general).

I can't really find this information and I'm just curious.
You can easily find info about big PC CPUs and GPUs but how about small, embedded ones?


texts: I recently bought a TFT module driven by SSD1963   I have experience on t6963 and ks0108 and by a quick look it seems ok to make a MCU interface to ATMega128. What is confusing to me is the difference between the supply voltage of SSD1963 = 3.3volts and micro bus voltage =5 volts. Should I reduce all voltages on the micro-controller's pins from 5 v to 3.3v?


texts: IR2110 driver output causing shoothrough despite deadtime

texts:
I'm having trouble with the ir2110 output. I'm working on a class d full bridge amplifier and I use 2 ir2110 to drive 4 irf540N mosfets. The switching frequency I use to generate the PWM is 240kHz and I include a 100ns dead-time (ideally would be no more than 50ns), but still got some peak in the output that generates shoothrough. In the picture you can see the circuit, that includes a snubber, the filter and load. The 2VM voltage is 15V.

The problem I need help with is that the deadtime is correct at the input of the ir2110, but in the output i get a peak (circled in red) which is causing the problem and I don't know what causes it. I tried with different values for the gate resistance of the MOS's, but when using a smaller value, 10ohms for example, the shootthrough is indeed smaller but not as small as I would like it to be, and the strange peak behaviour persists.

I get this shootthrough current:

The MOS capacitance and charge characteristics are as follows

In real life, I made the PCB and I'm getting the exact same result as in the simulation.

Thanks in advance.


texts:
I made myself a boost converter,
Since most of it is my own design (like inductor) I am surprised that it works, despite having very little knowledge of electronics, that is why I am skeptical and have a few questions.

I read somewhere not to connect battery or controller first (forgot which one was it), because I coded it myself and added some software power surge/failure protection, slow start etc. Do I need to care?

Some protection for micro controller is usually mentioned but I don't get what does it mean?

Do I need some discharge resistor for the MOSFET or the low signal discharges the MOSFET? (it is a logic level MOSFET).

I am using esp8266, using 40 kHz as frequency which appears to be max by docs, Any way to confirm if it is indeed generating 40 kHz without oscilloscope?

How important is input capacitor? I currently have none.

Output capacitor is 50v 1500 uF, is it good enough? Do I need bleed resistor? Do I need a ceramic capacitor in parallel to deal with the high frequency noise?

Lastly, if I build it on a PCB instead of breadboard, will it perform better?

Some pictures:

Circuit uses P40NF03L MOSFET and stps20h100ct Schottky Diodes, 5.1k + 330ohm voltage divider, Inductor has dual coil winding (parallel)
Update: Schematic


texts: Inductor Voltage and Current Phase Delay on a DC Converter

texts:
We learn that inductors introduce phase delay between voltage and current for AC. On a DC-DC converter, such as boost, we have, at the inductor, a DC component superimposed with AC component with many harmonics (i.e. triangle). As the boost converter voltage, we have a square wave.

Many researchers discuss phase error between I and V, and that it is especially significant for low permeability cores. How would one go about measuring the phase between the two (in the context of a Boost converter)?

To help illustrate the question and why I am confused by this, I have attached an image of the voltage and current of the inductor of a boost converter. The converter is operating at 30% duty cycle. The inductor's core magnetic material is a low permeability sendust (\$\mu_r = 75\$). Is there even a phase shift here?

Edit: Thanks for the suggestion, here are some papers where phase delay is discussed:

https://ieeexplore.ieee.org/document/7930799 Addresses the error introduced by the phase delay
https://ieeexplore.ieee.org/document/7846098 Addresses the error introduced by the phase delay
https://ieeexplore.ieee.org/document/5542385 Talks about it in his article and adresses it
https://ieeexplore.ieee.org/document/6559314 Also addresses phase delay (This one on a Boost converter as well)
https://ieeexplore.ieee.org/document/4432686 Also addresses the issue.


texts:
A few MOSFETS have failed on my motherboard.  And I was looking on the web to find a replacement for the ones that have died.  The ones that are currently on my motherboard are NEC 2SK3919. The only problem is I can not find any MOSFETS on Mouser.com ( or any site ) that had similar values to mine.

So I was wondering what values can be slightly higher/lower and what can not be changed.  I think that Vds and Vgs must be the same, but the td(on), td(off), QG, can be different, correct?

I know the motherboard is fairly old, its a HP Nettle2-GL8E, so some might say to replace the board, but I would like to learn MOSFETS and what happens to the DC current once it goes in the PSU.

Thank You!


texts: What is the purpose of an inductor on an incoming AC line?

texts:
I am trying to build the following schematic. It is a AC/DC converter from Cui link

I do not understand the function of L2. What is its purpose?
I am having a very hard time finding L2 for sale. Most inductors with a value of 5 mH are out of stock, and the selection is very poor. Could someone recommend a more common value that would still work in this schematic?


texts: How are LFSRs used in real applications as PRNGs?

texts:
I am programming a LFSR (Linear Feedback Shift Register) in software for learning purposes, and have encountered some limitations in its use as a pseudo-random number generator (PRNG).

If the seed have few '1' bits and few taps are used, it requires a large "startup time" to produce apparently random output, with almost equal distribution between '1's and '0's or short '0's runs. I guess with more taps such startup would be far quicker, but all precalculated tables I find give two or four taps.
Sequential numbers are highly correlated, which is to be expected, given that if the output bit is 0 the next number will be half of the previous one. For a 15-bit LFSR with taps [15, 14], plotting a pair of sequential numbers as points in a plane gives the following. An ideal PRNG should spread these points all over the place.

I know that LFSRs are used as fast hardware counter, but I've also seen it is used as a PRNG to create white noise. How is it used in such real world applications with such poor quality?


texts: Can I wire these automotive peltier heating/cooling devices as on/off without a temperature controller?

texts:
I have an seat removed from a Lincoln MKX that I mounted using scrap wood and heavy casters to use as an office chair that has power adjustment as well as Peltier heating/cooling components in the cushion and seatback. It was simple to get the seat positioning/lumbar support functions all working just by using a 30A 13.8V DC power supply and connecting (-) to GD145 and (+) to SBB61 (refer to pin mapping in first image).

I am having more difficulty trying to figure out how to wire the heating/cooling components, since when it is in the vehicle the heating/cooling settings are selected through a climate control module on the dash, which I do not have. I do have the dual climate controlled seat module (DCSM, with hot/ground connections shown in image 2, full wiring diagram in image 3), and was wondering if it would be possible to wire the Peltier devices using a 3-way toggle switch (HEAT ON / OFF / COOL ON) and bypass the temperature sensors, to basically run at full blast heating or cooling?

Related: image 4 is information from diagnostic instructions I found for a different year/model, but related vehicle (Navigator) which discusses how the Peltier devices in that vehicle are controlled. It seems that max power for that seat fan is 8V. Could I bypass the entire DCSM and wire the Peltier devices directly to my power supply/switch? Would i need to use a 1Ω/30W resistor to drop to 8V at 7.5A for the fan?


texts: Making a mobile battery charger for smart phones

texts:
i want to make a mobile charger and charge multiple mobiles at a time
therefore i select a 5V 2A adapter and a USB hub with 4 ports check the image

what i am going to do with this adapter and USB hub is, i will remove the USB HUB circuit so that electricity goes directly to USB port and just use the USB ports for chargers by making a series connection directly from adapters to USB ports so that each port supply 5V constant and 2A if incase only 1 mobile is connected

Now my question is what i am going to do is correct ?

Is there any other safe way to do this ?

what is the safest way to make a charger ?

Should i remove the USB HUB circuit or no need ?

Just with this 2 items i can charge multiple mobiles at a time and charge it with 2ampere ?


texts:
I wonder which hardware will be the best for playing with USB because its looks like a lot of projects only use atmega8 (or even attiny). But would it really be easier with an AT90USB which have the built-in USB?

I have already looked at some HID libraries (lufa, avr-usb, v-usb…) but they are complex. Does anyone have a link to a specific project or a one-case explanation of the USB implementation?

For the details : I would like to make a ~25 button joystick and I work on linux.


texts: How to calculate audio rms level from basic oscilloscope image

texts:
I have a broadband noise source based on a 24V Zener diode that looks like:-

You'll notice that it's  asymmetric about 0V, but let's ignore that for ease of calculation.  The noise is buffered prior to sampling with a TL081 op amp that has a bandwidth product of 3MHz.  I think that makes 3MHz the frequency choke point within my little circuit. The Ampl value of 1.02V is actually a peak to peak measurement.

How can I determine the RMS noise level for only the audio range?


texts: Are Keep outs with height (3d keep outs) essentially keep In?

texts: I have a translucent "keep out" box in my IDX file (NX) that sits on top of my PCBA. Does that mean the EE is only allowed to place components only within said box?


texts:
I’m trying to sum my car stereo output. Factory output has bass on one output and mid and tweeter on another output giving me 2 channels for left and 2 channels for right.

Ideally I’d like to sum them together and would of used something like a PAC LP7-4 however there doesn’t seem to have any availability in the U.K.

Is it possible to sum them by using 10k resistors and not cause any problems to the factory system?


texts: Do I need a 48V switch for a voltage divider circuit?

texts:
I need to use a rocker switch to turn on a MOSFET. I wanted to use a MOSFET to control when the current flows because I don't want to use a large switch to handle a large amount of current.
This is a simplified circuit showing the main concept. Since this switch is part of a voltage divider circuit, would I need to select one that's rated for 48, or would I be able to get a way with using a switch that is rated for (at least) 36V, per this example?

simulate this circuit – Schematic created using CircuitLab


texts: Reading time from text file in vhdl code

texts:
I want to read time value from a text file in vhdl code.

wait for 60 ns;

In the above command, I want to read 60 from a text file.
library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
use STD.textio.all;
use ieee.std_logic_textio.all;

entity example_file_io_tb is

end example_file_io_tb;

architecture behave of example_file_io_tb is

  component module_ripple_carry_adder is
    generic (
      g_WIDTH : natural);
    port (
      i_add_term1 : in  std_logic_vector(g_WIDTH-1 downto 0);
      i_add_term2 : in  std_logic_vector(g_WIDTH-1 downto 0);
      o_result    : out std_logic_vector(g_WIDTH downto 0)
      );
  end component module_ripple_carry_adder;

  file file_VECTORS : text;
  file file_RESULTS : text;

  constant c_WIDTH : natural := 4;

  signal r_ADD_TERM1 : std_logic_vector(c_WIDTH-1 downto 0) := (others => '0');
  signal r_ADD_TERM2 : std_logic_vector(c_WIDTH-1 downto 0) := (others => '0');
  signal w_SUM       : std_logic_vector(c_WIDTH downto 0);

begin

  MODULE_RIPPLE_CARRY_ADDER_INST : module_ripple_carry_adder
    generic map (
      g_WIDTH => c_WIDTH)
    port map (
      i_add_term1 => r_ADD_TERM1,
      i_add_term2 => r_ADD_TERM2,
      o_result    => w_SUM
      );

  process
    variable v_ILINE     : line;
    variable v_OLINE     : line;
    variable v_ADD_TERM1 : std_logic_vector(c_WIDTH-1 downto 0);
    variable v_ADD_TERM2 : std_logic_vector(c_WIDTH-1 downto 0);
    variable v_SPACE     : character;

  begin

    file_open(file_VECTORS, "input_vectors.txt",  read_mode);
    file_open(file_RESULTS, "output_results.txt", write_mode);

    while not endfile(file_VECTORS) loop
      readline(file_VECTORS, v_ILINE);
      read(v_ILINE, v_ADD_TERM1);
      read(v_ILINE, v_SPACE);
      read(v_ILINE, v_ADD_TERM2);

      r_ADD_TERM1 <= v_ADD_TERM1;
      r_ADD_TERM2 <= v_ADD_TERM2;

      wait for 60 ns;

      write(v_OLINE, w_SUM, right, c_WIDTH);
      writeline(file_RESULTS, v_OLINE);
    end loop;

    file_close(file_VECTORS);
    file_close(file_RESULTS);

    wait;
  end process;

end behave;


texts:
I'm trying to understand the proper way to design a PCB to interface a Xilinx 7-series FPGA with a Marvell 88E1512 Ethernet PHY, without simply copying the design from an existing schematic.
The interface is a RGMII v2.0 with 3.3V LVCMOS as the IO standard, as stated in the Marvell datasheet. Not much is said in the Marvell datasheet about the impedance and termination requirements for the RGMII. As a matter of fact, it's not super clear what the output impedance is of a 3.3V LVCMOS driver from the FPGA either. I have gathered from some forum posts that it depends on the drive strength setting as well as the IBIS model. Unfortunately, I don't have access to any IBIS simulation modeling tools.
I can think of 2 scenarios for the FPGA output:

The LVCMOS driver is very low impedance, so I should add a series resistance to conform to a specific characteristic impedance.
The LVCMOS driver is already designed to implement a specific output impedance.

and I can think of 2 scenarios for the Marvell PHY:

The termination is handled internal to the chip, so no external termination resistor is needed
An external termination resistor is required.

The RMII routing guideslines from Cadence recommends a 50 ohm trace impedance, but no real rationale is given.
I have too many unknowns: Can someone give me some hints? What is the correct configuration, and how would I have extracted this from the datasheets?


texts: AC LC Filter for a Solenoid - Unexpected Behavior

texts:
I've been working on a circuit that uses a microcontroller and an H-bridge with 34VDC supply to control a variety of low voltage loads including 24VAC solenoids at 50/60Hz (SHEPWM waveform to knock down harmonics) and 12VDC (classic PWM waveform @ 500Hz switching frequency).
The classic PWM is working fine, no mystery there. Where I am struggling is how to properly design a filter that will create a (more or less) smooth AC signal for the 24VAC solenoids. The 24VAC solenoids are assumed to have inductance of 100mH and 200mH in the on and off state, respectively. My starting point was to use an LC filter as shown in the attached reference schematic.
To get some clue about what is going on (instead of merely guessing) I created the attached LTSpice model. It treats the H-bridge as a voltage source switching between +34VDC and 0VDC in the top half of the AC cycle and between 0VDC and -34VDC in the bottom half. The nominal resistance of the H-bridge is accounted for. In simulation I am able to adjust L and C values to get a decent sinusoidal waveform for the solenoid, but in real life the o-scope (and the chatter of the solenoid) is showing a very different story - it's pretty much scrambled and there appears to be some ghosting up to around 70VDC.
The following two images are measured from GND to the lower side of the inductor in the following setup (ignore the value of the inductor in the diagram):

This is with a 50uF capacitance (5 parallel 10uF/50V capacitors) and three 1mH inductors in series

and this is the same setup with only about 500uH of inductance;

So far I have tried the following:

Adding bulk capacitance to the 34VDC supply (electrolytic, up to 470uF) to deal with the current spikes
Various values for the inductor L ranging from 330uH to 1000uH, and even 3x 1000uH in series
Various values for the capacitor C ranging from 10uF to 470uF, bipolar electrolytic type
Various values for the capacitor C ranging from 10uF to 5x 10uF in parallel, MLCC type

Can anyone suggest possible directions to explore to get the desired sinusoidal output? Do I need to use a different type of inductor or capacitor? Do I need to look at another filter type like LCL or something else altogether? What's bogus about the LTspice model?


texts: Convergence problem in pspice but not in ltspice

texts: I am trying to simulate a circuit in LTSPICE and it simulates without any convergence problems. However when I copy the netlist into pspice and try it simulate it I get strange results. It keeps saying convergence problems in pspice. However in LTSPICE it simulates the circuit correctly. Does anyone have any ideas why this is happening?


texts:
How does an op-amp know where the ground is because the inputs are single wires, how does an op-amp compare them to a ground like this circuit for example

clearly the op-amp is not connected to ground


texts: Is it correct that in a hard disk both surfaces of each disk are capable of storing data?

texts:
I have read that in a hard disk both surfaces of each disk are capable of storing data except the top and bottom disk where only the inner surface is used.  Is it correct if yes then why is are there read/write heads on top and bottom?
From CBSE Class X1 Computer Science textbook:

Hard disk: A hard disk consists of one or more circular disks called platters which are mounted  on  a  common  spindle.  Each
surface  of  a  platter  is  coated  with  a  magnetic material.  Both
surfaces  of  each  disk  are  capable  of  storing  data  except  the
top  and bottom  disk  where  only  the  inner  surface  is  used.
The  information  is  recorded  on  the surface  of  the  rotating
disk  by  magnetic  read/write  heads.  These heads  are  joined  to
a common arm known as access arm. This arm moves over the surface of
the rotating disk

Also you can see the same thing in this link.


texts:
I am considering to use digipot for designing programmable gain amplifier.

I will have to amplify 1MHz sine wave signal.

Looking at the datasheet of AD5243, I came across two parameters.

Bandwidth = 4.8MHz
Vw Settling Time = 1us

What does Settling time refer to? Does it mean that the settling time when I change the position of the potentiometer?


texts:
I'm reviewing nodal analysis on sinusoidal steady state circuits which my textbook typically only does mesh analysis on and I can't seem to get to the answer they obtained for an example problem.

They obtain this after mesh analysis.

My thought is that the middle node and top node are my only essential node but I assume that I'm treating it wrong since I'm not obtain the same solution.
Does anyone have any insight here?
This is simply for practice and my own knowledge.
Edit:
I obtained:
$$Io = 1.11897\angle19.5104°$$
The book obtained:
$$Io = 1.465\angle38.48°$$


texts: Voltage feedback reference issue with buck converter

texts:
I've couple of questions regarding the buck converter.
I've been trying to design a buck converter for MPPT circuit which is in Low side switching configuration, as shown in the below diagram.

simulate this circuit – Schematic created using CircuitLab

The voltage source shown in the circuit diagram is the PV panel voltage. The block shown is Arduino Nano whose ground is connected to the power ground of the panel. The mOsfet is driven by TLP250H opto-coupler low side mosfet driver with pwm signals generated from arduino. I need to take voltage feedback across load. But the problem is I'm confused where to take the reference and how to measure the voltage across load to feed the feedback signal to arduino. I've tried measuring the differential potential across Load and the power ground using two potential dividers across the pv panel and ground and load ground. But when measuring the potential difference across the load- and ground, the obvious result was a switching waveform as I'm trying to measure across the Mosfet drain to source terminals directly.
Please help me solve this issue in getting the voltage across the Load resistance/ across the filter capacitor.

Another question.. The voltage waveform across the capacitor is a clean DC along with spikes with peak-peak voltage of almost 6V. How do I reduce the spikes from the output waveform and what type of capacitor should be normally considered for a switching converter of this kind.

Thank you very much for your help.!


texts:
I have problems to solve the next exercise about maximum power transfer.

I know that potentiometer has two internal resistors. In this exercise, I must find the \$R\$ value to transfer maximum power to \$R_{L}\$. Now, I have two ideas:

To consider \$R = 500\Omega\$. If I perform it and then get Thévenin equivalent, simply \$R_{th} = 0\Omega\$ and \$V_{th} = 12V\$. Here I can't use the formula:
$$ P_{max} = \frac{V_{th}^2}{4R_{th}}$$

but the transferred power to \$R_{L}\$:
$$ P_{R_{L}}= \frac{(12V)^2}{100\Omega} = 1.44W$$
To assume \$500\Omega = R + R_{1}\$. In this case (\$R_{1}\$ is the other potentiometer resistor), \$R_{th} = R||R_{1} = R_{L}\$ (based on maximum power transfer theorem). I solve a quadratic equation and:
$$R = (250 \pm 50\sqrt{5})\Omega\\V_{th} = \frac{12R}{500}V$$ and implies two different Thévenin voltages. Performing power calculations, I get:
$$P_{R_{L}} = 36(3\pm\sqrt{5})mW$$

Definitely, the first approach gives a higher power (and suppose it's maximum power transferred by the source) , but which is correct?


texts: What type of connector is on this UJ-844 DVD drive?

texts:
This is a DVD multi UJ-844 drive, but I can't identify the connector correctly online.
Here's what it looks like:


texts: TVS diode for surge protection: how does it works beyond Ipp point?

texts:
I need to protect the schematic from the surge transient voltage 1.0 kV 1.2/50 us (standard surge model).

To accomplish this I planned to use two SMBJ200CA TVSs in series at the input and make all following circuit withstanding up to 800V voltage:

I have a filing that this schematic will work fine. However TVS's will work in the unspecified area. Let me explain:

In the datasheet specified that the clamping voltage (Vc) of this part is 324V and the current at this point (Ipp) should be 1.9A:

If I'd look further in the datasheet I will see the voltage-to-current chart ending with Vc/Ipp point:

I checked out Littlefuse, Bourns and SMC Diode Solutions datasheets for the information regarding how it will behave beyond this point - no information :(

I think that 1.9 Amps is definitely not enough for protection. I estimated that the current in the worst case scenario should be up to 500 Amps - 250 times more than specified and I have no source for estimation.

The only thing I can do - put the real device(s) to the test until destruction and made some estimation upon these tests. But I don't like to use any device under unspecified condition as I can not be sure for these specs.

I'd spell the questions in the following way:

Do you share my opinion that this schematic will work fine in real world?
Is TVS a right device for this purpose? Or should I add anything extra to the schematic to make it more reliable (or move working points to the specified area)? I don't like varistors as they are big, expensive and fire-able.
Please share any of your thoughts on the subject...


texts:
In computing, firmware is a computer program that is "embedded" in a hardware device, that is, an essential part of the hardware. It is sometimes called embedded software.

I got this definition from Wikipedia and I am getting confused of the terms firmware and software. Can you give me clarification about these.


texts:
I am using MUX 4051(8:1 Mux and 3 select lines) IC in my application.

My question is regarding magnitude of Output selected by select lines.

Is Output voltage magnitude which is selected by select lines same as what we are assigning at input of MUX ( 8 pins )irrespective of VCC voltage of MUX((3.3v/5V)?


texts:
I am learning Altium Designer and therefore I've shosen simple audio project. For the sake of Multichannel Designm I've created simple audio input port, which I am multiplying with Repeat command and here is root sheet:

As you can see, AUDIO_INPUT is multiplied 8 times using Repeat command and here is AUDIO_INPUT "zoomed":

Now, when I try to compile the project, I get following error(s):

Class   Document    Source  Message Time    Date    No.

[Error] Sheet4.SchDoc   Compiler    Duplicate Component Designators J2 at 2950mil,5050mil and 2950mil,5050mil   20:05:54    16.05.2018  1
Class   Document    Source  Message Time    Date    No.

[Error] Sheet4.SchDoc   Compiler    Duplicate Component Designators J3 at 2950mil,4050mil and 2950mil,4050mil   20:05:54    16.05.2018  2

What did I do wrong? I tried to reannotate designators, I get same error.
Nomenclature:

Sheet4.SchDoc is root sheet
Sheet2.SchDoc is audio input sheet

I have deleted from and placed problematic components back to schematic and now the errors(s) are gone. But can someone tell me why?

ADDENDUM:
I have forgot to tell my project is under version control and I've commited project to repository, then deleted the contents of .Annotation file (I've left the EMPTY file itself in project structure) and it compiled ok, but I hardly beleive this is the right way to fix this problem.


texts: How to create a circuit to automatically raise/lower a height-adjustable desk?

texts:
Background
Hello everyone, I'm working on a small project where I can control the height of a height-adjustable desk using a microcontroller, MOSFET transistors, and an ultrasonic sensor. Essentially I want the user to input a height and the desk to automatically adjust to that height.
Technical details
This is the desk I am using. It only has up/down buttons and has no "memory" features.
I was trying to use this tutorial, but because I did not have an easy access to the motor itself, I decided to "replace" the up/down buttons with MOSFET transistors.
This is a MOSFET I am using. It has a Vgs threshold voltage between 2-4 volt, which will work for my 5v microcontroller.
I opened up the button box and here is what it looks like.

There are four wires going in the JST connector.

Red : 30V
Black : GND
Green : Down
White : Up

This is an active-high switch where connecting either Green or White to Red will move the desk down and up, respectively. See below diagram for how the switch (Omron SS-5) does in the schematic.

What I did so far
I pulled out the JST connector and connected jumper wires directly to the female pins to create the following circuit for raising the desk.

The voltage source on the left-side is the digital-out pin of a microcontroller. I was successfully able to raise the desk when the pin was high and stop raising the desk when the pin was low.
Edit(August 16th 2020): I measured the current from the source of the transistor to the white wire, and it spiked to ~3A for a brief moment, and while the desk is rising(i.e. when the motor is operating), it outputted ~300mA.
I was also able to do the same for lowering the desk, except that the source of MOSFET was connected to the Green wire instead.
My problem is:
I placed another transistor as such to do both raising and lowering:

Edit(Aug 15th 2020): Sorry about the confusing diagram. This diagram DOES use two digital output pins. The voltage source on the left side is D2 of MCU and the one on the right is D3 of MCU. The pins share a common ground, which is responsible for the following problem.
This obviously created a problem because the source of both transistors are connected to both White and Green wire, meaning that every time one transistor is on, both White/Green wires are HIGH. This is equivalent of pressing both buttons at the same time, which doesn't move the desk at all. I tried putting 10k resistor between the two sources of the transistors, but that did not solve the problem.
My question

How should I edit my circuit to fulfill what I am trying to do?
Is this something I can even create just by using transistors? or
Do I need to open the motor to follow the typical use cases of transistor-as-switch?

I would greatly appreciate if anyone can give advice on my situation :)
I am more than happy to clarify any confusion.
Thank you!


texts: Voltage Drop/Sag - Current Limited Source

texts:
I'm tinkering with the idea of adding a display for gear position on my motorcycle. It already has a gear position sensor that connects a different resistor in series to ground, depending on the gear that is selected. There is only a single wire out of the gear position sensor that connects to the ECU.
Given that all I have is these varied resistances to ground to indicate the selected gear:

What is the best way to convert this to a voltage signal (0.1v to 5v) that the display (which is programmable for a voltage level in each gear) can use?
(best being largely defined by being compact in physical size, reducing the amount of power consumed in the circuit, producing a stable voltage reading even if VCC varies or spikes, and being reliable even in vibration prone environment).
One way I can think of is to use a voltage divider with a fixed pullup (say 1200kohm, with Vcc of 5v from a 12v to 5v buck converter) and then tap the center point between that and the gear position sensor.
Is there other ways of doing this though, for instance, can one use a nominal 5V current limited source (12v to 5v buck converter as above) and connect it directly to the GPS and just measure the sag at the voltage source output?
Is that a bad idea for some reason?
I know the divider circuit would work, just curious how else this could be done?
Thanks!


texts: Can any one recommend / compare performance of digital inverter and analogue inverter for home UPS application? Which one is better, Analaogue or digital ? and why?


texts: How to compensate for weather changes in barometric pressure sensor (BMP180)?

texts:
I am using BMP180 barometric pressure sensor on an elevator for extended periods (months together), below is the guidance from Sparkfun.

Sparkfun guidance: “You should also remember that pressure changes due to weather will affect your altitude readings. The best accuracy will be obtained if you take a “fresh” p0 (baseline/reference pressure) when you need it and don’t rely on it to be accurate for extended periods due to changes in the weather”

How can I obtain a fresh p0 (baseline/reference pressure) when the elevator is continuously moving ?


texts: HDMI Mixer/Blender/Superimposer-Chip (2 to 1) wanted

texts:
Is there a chip on the market which can overlay one HDMI-input over another ?

Chip should have 2 * HDMI -IN and 1 * HDMI-OUT

HDMI-IN-1 connected with Sat-receiver or other TV-Source
HDMI-IN-2 connected with Android-Box or Network Player

The Menues of HDMI-2 shall be superimposed/blended/overlayed over TV-Screen of HDMI-1.
e.g. by replacing the black background color of Android-Screen with TV-Screen-Pixel.

If superimposing is not available a splitscreen function would be sufficient, e.g. upper or lower part of HDMI-OUT reserved for HDMI-2 IN and rest for HDMI 1 in.


texts: PIC16LF1786 change PWM pin on CCP3 with APFCON1

texts:
PIC16(L)F1786 has 3 CCP modules. I need a PWM signal on RB5 pin which belongs to CCP3 module, as well as RC6 pin. BUT, when I am setting up the PWM according to the datasheet (page 277), I am getting PWM signal on RC6 instead of RB5, even though in APFCON2 register CCP3SEL bit is set to 1. Is it even possible to get PWM on RB5 instead of RC6. And one more "BUT": I am using Proteus to test the firmware, and I am do not know is it a bug in Proteus or I am missing something. I am 99% sure I am doing something wrong since this is my 2nd day of PIC micro controller programming.

Thanks.

Below I am listing configuration and my code in MPLAB X IDE using RC8 compiler:

#pragma config FOSC = INTOSC
#pragma config WDTE = OFF
#pragma config PWRTE = OFF
#pragma config MCLRE = ON
#pragma config CP = OFF
#pragma config CPD = OFF
#pragma config BOREN = ON
#pragma config CLKOUTEN = OFF
#pragma config IESO = ON
#pragma config FCMEN = ON

#pragma config WRT = OFF
#pragma config VCAPEN = OFF
#pragma config PLLEN = OFF
#pragma config STVREN = ON
#pragma config BORV = LO
#pragma config LPBOR = OFF
#pragma config LVP = ON

#include <xc.h>

void main(void) {
    TRISA = 0x00;
    TRISB = 0x00;
    TRISC = 0x00;
    TRISE = 0x04;
    TRISBbits.TRISB5 = 0x01;
    TRISCbits.TRISC6 = 0x01;

    PR2 = 0x63; // PWMPeriod = (PR2(99)+1)*4*TMR2_Prescale_Value(1)/(f(8 000 000)) = 20kHz
    CCP3CONbits.CCP3M = 0x00;

    // CCP3M Mode Select bits 11xx = PWM mode
    CCP3CONbits.CCP3M3 = 0x01;
    CCP3CONbits.CCP3M2 = 0x01;

    CCPR3L = 0x32;
    CCP3CONbits.DC3B = 0x00; // CCP3L:DC3B = 0x32:0x00 = 00110010 00 = 200 DEC

    PIR1bits.TMR2IF = 0x00;

    APFCON2bits.CCP3SEL = 0x01; // CCP3SEL: CCP3 Input/Output Pin Selection bit, if 1 then CCP3 is on pin RB5

    //Timer configuration
    T2CONbits.T2CKPS = 0x00; // Timer prescale value 1:1
    T2CONbits.T2OUTPS = 0x00; // Timer postscale value 1:1
    T2CONbits.TMR2ON = 0x01; // Enable the Timer

    while(!PIR1bits.TMR2IF) // Wait until the Timer overflows and set the TMR2IF bit of the PIR1 register
    {
        TRISBbits.TRISB5 = 0x00; // Enable the CCP3 pin output driver
    }

    while(1)
    {
    }

    return;
}


texts: Calculate electromagnetic torque of synchronous motor?

texts:
I usually use this formula $$P=Tω=Τ\frac{2π}{60}n$$

where n is revolutions per minute and P is the power depending on the occasion.

Since we have to deal with a synchronous  motor we have to use the synchronous speed Ns. My big problem is what power should I use. I have everything, power input, power output, all the losses. How should I replace P to find the 'electromagnetic' torque.


texts:
I am designing a DIY BLDC ESC. I am able to detect the '0' crossing correctly (for the BEMF approach). It locks onto the '0' crossing (1.jpg).
Then it stays good for a couple of iterations (2.jpg). But then it slowly looses control (4.jpg) and finally looses it completely (5.jpg).
This happens a couple of times and finally it is lost as shown in 5.jpg.
Why so. Why does it not follow the commutation time properly. Please note that I am looking at '0' crossing only during the initial stages. I save the commutation time value when '0' crossing is detected and keep commutation at that saved time value only.
DO I need a dynamic '0' crossing. DO I need to keep looking for '0' crossing even after initial '0' cross detection !!!!

Reagards,
Vinod.


texts:
I feel like a total newb here, because I've built resonant tank circuits plenty of times before, but somehow I'm stumped on this one.  I've run into a bizarre problem I can't figure out.

See scope shot:

The top channel is my signal to the gate of a mosfet.  The mosfet is driving a tank circuit that contains a large coil wrapped on ferrite with a 5uF capacitor.  The coil is large enough that the frequency is near 100Hz.

The bottom channel shows the positive side of the tank capacitor where the mosfet source is connected to drive the circuit. What I'm confused as heck about is the low voltage delay after the input turns off and before the initial oscillation begins.  I don't recall ever running into something like this before.  I've traced my circuit leads and double checked everything and I just don't know what's going on.  Anyone else ever seen something like this in a tank circuit?

Ok here's a circuit diagram.  I should have posted before, but I doubt this is going to help:


texts: Using an old Bluetooth-enabled Blackberry as a GPS

texts:
I have a few Blackberry devices with integrated GPS functionality.  Given that the SIM is no longer activated, is it possible to use this device as a second hand GPS unit?

My thought is that I can communicate with it over Bluetooth with my custom FPGA.

Has this been done before?


texts: How does one calculate the resistor in parallel with the MOSFETs?

texts: I would like to know more about the resistors again in parallel with the MOSFETs in the picture. The Si2365EDS is a P-channel transistor and the 2N7002 is a N-channel transistor. How does one calculate the resistor in parallel with them? How does one know when the value of the tension of VGS is definied and the tension in which the state of the MOSFET will act as a closed circuit(when used as a switch)?


texts: Logic circuit for not accidentally driving a GPIO output

texts:
I am developing a system which will have several devices attached to it. I will have a massive software running on it which controls all of the devices and communicates with different units.
One of the devices sprays all of its paint content at once when triggered. It is a third party device, it is tightly sealed, I cannot remove the paint container from it. It needs to be connected to the system all the time, because I need to communicate with it periodically. And when it is triggered, it becomes useless, and needs to be replaced with a new one.
The problem is, if I accidentally trigger this output during the development stage, it will create a real mass in the laboratory, and it will cost money since it needs to be replaced. I want to avoid this as much as possible.
As a solution, I came up with an idea of inserting a logic circuit between the MCU and the device. If a certain sequence of logic pattern (e.g.; 010, 110 and 011) is sent from the GPIO outputs, it will trigger the device. I want to avoid an accident because of shorting this GPIO wire to logic-high state, or changing it in the code.

simulate this circuit – Schematic created using CircuitLab
What other means can be used? Is there an IC (which is controlled over GPIO, I2C or SPI) for this purpose?


texts: Is there a change in the voltage/current when motor is locked up? How can one sense this?

texts: I am working on a motor control system, and I'd like to be able to know when the motor has reached its max output and has locked up (shaft no longer able to rotate, due to mechanical force pushing back).  The motor will be used with a ball ramp mechanism to create a linear motion. I need to know when the motor stops spinning so that I can move on to the next task in the system. What would be the best/most efficient way to do this?


texts: Complex Amplitudes and Exp'l Increase/Decrease

texts:
The following are quotes from a textbook,

  If S(t) is represented as a rotating phasor, the angular frequency
  of the phasor can be thought of as velocity at the end of the phasor.
  In particular the velocity \$\omega\$ is always at right angles to the
  phasor.  $$\mathbf S(t) = Ae^{j\omega t}$$

  However when we consider the general case when the velocity vector is
  inclined at an arbitrary angle \$\psi\$. In this case is a velocity is
  given by the symbol \$s\$ which now is composed of a component
  \$\omega\$ at right angle to the phasor as well as a component sigma
  which is parallel to \$s\$

Question1: I'm not able think about a complex number whose derivative is not \$i\$ times something, since any complex number can be represented by \$e^{jt}\$, their derivative is given by \$j e^{jt}\$ which means the velocity vector is perpendicular to the current position. But in this "general case" the velocity vector is pointing at an arbitrary angle, how?

Question 2: If the velocity vector is pointing in an arbitrary direction, then it's stated that the amplitude increases or decays "exponentially" Why is this true? Why not some other rate of decrease or increase?


texts: How can I make my measurements of full-wave rectified AC using an A/D match a Fluke meter on its DC range?

texts:
I am trying to measure the DC voltage of a full-wave rectified 60Hz AC signal using an A/D and have it match what a Fluke meter reads on its DC scale. My current approach is to take as many (16 bit) samples as necessary in a measurement loop to measure a full 60 Hz cycle (16.6667 ms), then average the
 samples. I then take the A/D output and apply a scale factor to get the actual voltage reading to match what the Fluke says. But, when I apply a pure DC voltage (or a different rectified AC voltage) to the measurement circuit, the scaled result no longer matches the Fluke when measuring the same pure DC voltage. The results differ by more than 5% and the difference varies with peak-peak range of the rectified DC voltage.

So, I guess I'm asking how does a Fluke (or other) meter measure DC using it's internal A/D?


texts: How to measure an 15 kV electric fence to 0-5 v analog input of a arduino?

texts:
Good day

I am a mechanical engineering student who is dabbling in electronics right now and am having a little bit of trouble in one project

The Project: Making a gsm enabled voltage meter for monitoring electric fences.
The Problem: How do I convert 15 kV signal to 5 v that the arduino can read.
I have tried to make a voltage divider with a 10 M ohm and three 10k ohm resistors, but I found that it causes a minor shortage to ground when I wired it up. (I have a 0.3J 12v fence energizer which i use for testing and it went from 6.1 kV to 4.2 kV)

Extra:
I have a meter that I does not require a physical ground connection that looks like this:

I have identified most of the components execopt L3(top left) which is some sort of coil and the spring(bottom left) which i am not sure if is for pcb stabalization or a psuedo ground connection.

The Questions

What component is L3 in the picture above?(says on top 102k 06039)
The spring in the lower left corner of the picture of the pcb could it be used as a grounding mechanism of some sort. It touches some aluminium tape in the plastic enclosure and has no way to connect to ground?
What components are my best bet to use in this project for stepping down the voltage from 15kV to 5 V without draining the source? A transformer perhaps or are there any other circuits I could use, preferably without connecting to the ground wire of the fence but that's a preference not requirement.


texts: Need help identifying this component on pcb

texts:
Does anyone know what this component is?

Thanks


texts: I know that when the frequency is 0, the voltage will be pure DC. But in DSP and Digital Communication, I have seen mentioning of negative frequencies which I dont quite understand. For example, like \$ -f_{0}\$ to \$ f_{0}\$ frequency range. How could frequency become negative?


texts: How Gigabit Ethernet is achieved in fiber optics?

texts:
I understand how 1000BaseT works on Cat 5 cables: It uses clock rate at 125 MHz, 4D-PAM5 data encoding to transmit 2 bit per cycle and it uses the four pairs of the cable. The math is quite simple: 125 MHz x 2 bits per signal (i.e, per wire pair) x 4 signals per time = 1.000 Mbps.

How does this apply, for example, to 1000Base-EX single mode fiber technology? I know the data is encoded using 8b / 10b scheme, obtaining a speed rate of 1.25 Gbps, but this time only a pair of TX / RX lines are available for transmission with the sfp transceiver. Does the frequency change on the SerDes device? Do you stop using a 125 MHz clock?

In this case I could understand that the frequency increases in the SerDes device, but in the case of 10Gbps fiber transmissions, what is changed? I do not think it will come to use a frequency of such a high clock.


texts: What should a true RMS Voltage meter read on the load side of a zero fire SCR?

texts: I have a 3 phase zero fire SCR/SSR set that has 480V input. I put my Fluke 289 (which is a tRMS meter) across the different phases on the load side. Then adjusted the output. The voltage read ~470V from 0 to full output. I also switched my Meter to measure frequency and it read 59Hz regardless of the SCR output. Is this the result I should expect or is something wrong?


texts: Will a BPSK Demodulator designed for [ 0º , 180º ] symbols work for [ +60º , -60º ] symbols?

texts:
I am using an IQ-based digital demodulator circuit IC to receive and decode BPSK signals. It is designed for ordinary BPSK signals, which have [ 0º , 180º ]. However, the signals I am intending to receive are also binary, but the symbols are [ +60º , -60º ].

Will the demodulator work in this circumstances?

Thank you.


texts: Are SiC Mosfets better than Si Mosfets for Solar Charger in max 550V Range

texts:
The charger needs to handle the solar array's output of max 550V, but also efficiently handle lower voltages as weather/etc conditions degrade -- down to roughly 150V. It needs to handle between 15 - 50A. Thats quite the wide range of voltages and current, but is the nature of this particular solar setup. Efficient power conversion is of prime importance. I'll be using an MPPT type algorithm at the MCU with 5V output to the gate driver. PWM frequency will likely depend on the Fet used -- I'm assuming >50KHz. Output power to the batteries will be approx. 120V. Price isn't too much of a concern, hard costs need to come in at under $100USD per unit (but much less is preferable).
One of the options I'm currently looking at is Wolfspeed's 650V SiC Mosfet.
And, on the Si Mosfet side: OnSemi's Super Junction Mosfet.
From what I've read, SiC Mosfets really outperform Si in high power applications and in high frequency PWM drivers. It seems their current market value is in converting much higher voltages, up to 1200V. Those power levels are above the scope of my lowly project of only 550V.
My question is: Are SiC Mosfets an appropriate technology to incorporate into <=550V power switching? Will I gain power conversion efficiencies with them compared to other more standard Si Fets in that power range? Or, do those efficiencies deteriorate at lower voltages -- where Si Mosfets would do just as well?


texts:
I need to change this potentiometer that act as an encoder in a Native Instrument controller/mixer (Kontrol S5), as it has become faulty and increases values by itself at the lower end of its range... very strange! Having it fixed by NI would cost me about 300 $US with shipping, which is prohibitive, so I am looking to do it myself, as I have some experience with de/soldering.

I have searched for countless hours but have not been able to identify it. So far I gathered that the B103 marking says it is 10K linear, but I have no clue what the 5F2 marking means.

Other useful information:

has a center detent
has about 300 degrees of turn
shaft diameter 6mm and length 15mm
runs inside a 12V device

It looks like a Bourns PTV111 series, but those have a plastic shaft versus metal on this one.

Any help pointing me in the right direction would be GREATLY appreciated!

Here are images of the potentiometer :


texts: How to connect the power plane Microchip AN2587

texts:
In microchip AN2587: EMI, EMC, EFT, and ESD Circuit Design Consideration for 32-bit Microcontrollers Page 50 . The following power connection for Vdd is recommended (similar diagram in datasheet)
.

I drew on the picture 2 marks called vcc-1 and vcc-2 , which will become net labels in the pcb desgin.The Board is a 4-Layer stackup (Signal-GND plane-Power plane-Signal) .Now I am lost in what will the power plane be connected to ?

1- power plane is Vdd or cut into 2 parts 1 is vcc-1 and other is vcc-2 ?

2- if Power plane is Vdd, how should Vcc-1 and Vcc-2 be routed? top or in the power plane ?

3-Option #3 : use different 4-layer stack up (Signal+power- GND plane -GND plane-Signal+power) No vdd plane (idea taken from Henry ott EMC book )


texts: How are the values for the resistances and capacitor chosen in the circuit below

texts: In the circuit shown, the optocopuler is used as a solid state relay and the triac acts as a switch. i would like to know how the resistor values and capacitor value was chosen.


texts: Synchronising Power & Synchronising Coefficient

texts:
I am really confused with the concept of synchronising power and synchronising coefficient. I was taught 2 simple formulae in class.

P = 3VEsin(del)/X

Sp = dP/d(del) = 3VEcos(del)/X

Now, I am confused here with what is del ?

Below problem was asked in my class test. I have added the solution provided by my instructor.

This problem used del = Angle between V and E.

I tried to solve this problem and got stuck which value of del to use 9.85 or 3.

This solution provided in class used del = rotor displacement angle.

Both the solutions can't be correct at the same time. I tried to ask my instructor. His reply was "Do as it is given in the solution". Please help me to understand this concept.


texts: L297 stepper motor controller clock signal question

texts: How i can generate clock signal to L297 stepper motor controller with a PIC16f877 microcontroller?:


texts:
I am repairing a coin sensor on a game called Treasure falls.  The coin slides down a slot and covers over some type of LED.  Usually on games like this there is an IR LED emitter and detector but this one only has a detector of some kind and it is sensing the presence and absence of visible light.  I have a known good working unit and I sketched out the schematics on the pcb attached to this device.  It is an Op Amp with a transistor and eight  resistors and a LED that shows when the sensor is covered or open to light. It compares a set voltage to the voltage in the circuit with the sensor LED. The sensor that the coin covers is a diode of some type.  It looks just like a standard 5mm clear LED.  I checked on a meter and I get a diode voltage drop of 1.5-2.5V depending on exposure to light.  When I measure the resistance with a meter I get 75 ohms when it is exposed to light and up to 300 ohms when covered.  What I have learned so far is that it is a light sensing photo detector but I can't seem to find out how to track one down with the resistance range I need.  That doesn't show on the data sheets I have seen.  Usually data sheets cover almost everything you need but perhaps I don't understand how this resistance is calculated.  Is this resistance supposed to be on data sheets or is there another way to figure out the resistance from the data sheet?  The manufacture won't provide the info on this unit and won't sell us the part.
Thanks,
Russ


texts: Help understanding how to use Thévenin's theorem in order to solve a first order circuit

texts:
simulate this circuit – Schematic created using CircuitLab

Assuming the above circuit is given, and I need to find the voltage V on the capacitor for all t (v(t)).
The controled current source is given by I=10^(-4) * v0 while v0 is the voltage on the resistor on the right.
The switch turn right at t=0.

So, i figured easily that the voltage of the capacitor right before the switch turn right is 100v.
And of course that after the switch turn right i get the circuit:

simulate this circuit

Now, I'm trying to use Thévenin's theorem in order to focus only on the capacitor.
I know that i need to look for the voltage/current that drops/goes through the capacitor, but I can't seem to get there from KVL and KCL.
I'm stuck with 3 parameters: V, V0, and I throught the capacitor.
Did I figured the whole thing wrong?
Any tips/advices please.
Thanks.


texts: Determining safe current and fuse rating for LV LED lighting

texts:
My home builder pre-pulled a length of 18-8 solid copper wire (18 AWG, 8 insulated conductors inside single jacket) into the ceiling of a room where I want to use some LED lighting with a remote power supply (that is, the power supply is at one end of the 18-8 and the LED lighting is at the other end).  I can easily calculate the needed current / wattage for the lighting, but I'm having a hard time determining the various limits of the wire (current, voltage drop) to be safe and effective.

If I'm reading the charts correctly, this wire should be about 6.4 milliohms per foot and have an ampacity of 10 amps at 20degreeC insulation temperature and 60degreeC conductor temperature (not sure how that's possible or exactly how they measure that).

My LED lighting to be connected would draw no more than 52 watts, or about 4.3 amps at 12 volts or 2.2 amps at 24 volts.

My proposed power supply will happily provide 150 watts at 12 volts before its own overcurrent protection gets triggered.  Therefore, I believe it would be advisable for me to fuse the output connections before the long wire runs to the ceiling at some lower value to prevent the wire from becoming an ignition source in the case where the LED strip itself shorts out.

So my questions are:

How long a run of the 18-8 wire can I used before I run into problems?  Since the wire is already there and I'm loathe to tear out my ceiling, what are alternative solutions if my voltage drop is too high?  Can I pair up conductors in the 18-8 to have instead of 4 pairs, have 2 pairs of paired conductors?
What current value fuse would make sense?  I'm thinking 80% of the 10 amp ampicity, or 8 amps might be a safe value.
Have I read the charts and gotten correct values for resistance and ampacity?  Do my numbers sound right?

I'm an amateur at this -- my college EE courses are ancient memories.  I probably know only enough to be dangerous, as the saying goes.  Feel free to set me straight or advise me in anyway appropriate.  I'm not math averse, so if pointing me at the proper equations or references is appropriate, do that.  I can do the calculations, but as with anything engineered, there's rules of thumb, acquired wisdom and outside factors to consider beyond something as simple as E=IR.


texts:
Yesterday, there was a huge power surge in my area, and I wasn't able to connect to the internet any more.

The reason was that the Wifi modem was somehow automatically reset to its factory configuration. I had to reset it to my settings today to get it working again.

Is this a normal thing? How does it happen?


texts: How to make a conductor positively charged?

texts: I want to get a conductor positively charged for a long time. However, the charge shouldn't be so small so charging by friction is not a solution for me. I've heard if you connect the + end of a battery to the object the object gets positively charged whereas if you connect the - end of a battery to the object the object gets negatively charged. Is that true?


texts: I am designing a water level controller with discrete components. But when I use DC sensing, the probes are getting corroded... I want to eliminate the corrosion completely, perhaps using either AC or Pulsating DC. Can anyone please suggest me with examples?


texts:
so basically i ran on this schematic , an led Color Organ from Circuit Skills. Now following the explanation of the circuit i pretty much understand the basic principle of it. However i have some problems figuring out about two things(I am an entry level Electronics hobbyist, so sorry about the dumb questions).
Q1: The elements following the op amp (Red Rectangle) are supposed to condition the signal (ac signal from the aux jack), however are they really necessary ? And what is their purpose ? The ones in the yellow box i think are for smoothing the blinking of the Leds in order not the blink instantly but add a little dimming effect.

Q2: Here in the circuit they use "Virtual Ground" for the Op Amps, however can they be powered by a single supply ?

Hope i can get some answers from the Electronic Gurus .
P.S. Here is the link from the website Circuit Skills


texts:
Wikipedia gives following circuits of flip flops:

SR latch using NORs

SR latch using NANDs

Note that circuit 1 have R input at top and S below it.
Also note that circuit 2 have active LOW inputs, that is inputs with bar above them. The action columns of truth tables have entries in reverse order of each other.

I was wondering: if I flip inputs of circuit, S at top and R below it, will it still certify as valid SR latch, especially because the order of action is changed?
For example, Forbidden is no more adjacent to Set, but to Reset:


texts: 3.3 V LDO voltage regulator for microcontroller (STM32F103x)

texts:
I am looking to replace a 1 A switch mode supply with a cheaper (low-drop) linear voltage regulator to power a microcontroller with 3.3 V from 5 V supply (which is stepped-down from 24 V).

According to its datasheet, an LD1086 has 5 mA quiescent current that "flows into the load, increasing efficiency.". What happens if the microcontroller is haltet and only draws microamps?

Also, assuming max. current consumption (70 mA for the CPU without active outputs, plus active outputs) to be 150 mA at 3.3 V, could I use the DFN8 package of this LDO when powering from 5 V?

Approx. 1.7 V drop at 150 mA means 255 mW (1/4 W) loss.
DFN8 package has 33 °C/W junction-ambient thermal resistance, so it should be 8.4 K above ambient temp, correct?

Competitor LM1117 in SOT-223 has 61.6 °C/W resulting in theoretical 15.7 K above ambient. The datasheet suggests it needs a tantalum capacitor at the output for stability, which I would like to avoid. What needs to be considered in order to use a ceramic capacitor instead (e.g. murata GRM31CR71C106KA12L)?


texts: Sine wave to square wave - Schmitt trigger

texts:
I need to transform a bipolar sine wave (varies from -5 V to 5 V, 1 kHz) to a square wave for further digital processing (0 to 3.3 V), as in this image:

The important thing is that this sine wave can't be distorted, so there can't be any limiting diodes at the input.

I have got only 3.3 V and 5 V voltage supplies. An obvious way to go is an op-amp working as a Schmitt trigger, but I'm not sure it can handle -5 V at the input with a single positive 3.3 V supply.

Should I reduce the amplitude on the input by using a resistor divider? And perhaps add some offset voltage for the signal to fit the input voltage range of the op-amp?


texts: How this close loop control systems work?

texts: I have attached photo of a lecture where a slide is showing a close loop control system(theif repulsion system). But i am confused by the electric eye?how it is working?is the robber/theif so mad that he is carrying an IR source in his hand?(normally a theif is expected to have a pistol or knife in his hand)


texts: Is magnetic hysteresis present even with a DC bias?

texts:
Consider the following circuit:

With Vin(t) = A sin(ωt) for some given frequency ω.
The relationship between Vin and Vout is certainly non-linear, because of the effect of hysteresis in L's magnetic core.
My question:  is hysteresis non-linearity present even if Vin(t) = A sin(ωt) + B, where B is greater (possibly much greater) than A?
My intuition is that since the polarity of the current through L does not change, then there is no hysteresis.  An alternative intuition tells me that maybe it is the sign of the derivative of the current what counts;  i.e., the current rises through one curve, and lowers through a different curve (different sections of the magnetization curve), thus causing non-linearity.  However, I'm not sure that the math checks out with this alternative intuition, in that the output (the value of the y-axis) would diverge if you repeatedly go down at a low slope and then go back up at a higher slope.


texts:
If I feed a square wave into a first order, passive, low-pass filter (resistor and capacitor), I get the following results on an oscilloscope (sorry, I don't know how to scale and rotate images):

Why does the overshoot only occur on half of the corners of the square wave? Based on Fourier analysis, partial sums of a square wave should look something like this:

This is the Gibbs phenomenon. Here the overshoot occurs on all 'corners' of the square wave, rather than just the ones following a transition. I got some similar results when testing the frequency response of a unity gain buffer op amp:

Hypothetically, the op amp acts as a low-pass filter due to its finite bandwidth, so it's not surprising that it produces similar results to the actual low-pass filter above.

My question is: based on electrical theory, low-pass filtering should produce a square wave with attenuated higher harmonics, which should produce something similar to the Gibbs phenomenon with overshoot at each of the corners. Why doesn't this happen here? For me, it makes MATHEMATICAL sense that the output wave should have overshoot at each corner, but it makes INTUITIVE sense that the output should only have overshoot at the corners that occur after a transition. Why? Because if the 'ringing' (overshoot/undershoot) also occurred BEFORE a transition, it would seem non-causal - it would almost be as if the wave is guessing that it's about to transition!

How can I reconcile my understanding from the perspective of Fourier theory with what actually happens in real life?


texts:
According to plumbing analogy I've hard time seeing why power is measured in volts*amps, instead of just amps.

I found an analogy from http://science.howstuffworks.com/environmental/energy/question501.htm

  Electrical power is measured in watts. In an electrical system power
  (P) is equal to the voltage multiplied by the current.

  The water analogy still applies. Take a hose and point it at a
  waterwheel like the ones that were used to turn grinding stones in
  watermills. You can increase the power generated by the waterwheel in
  two ways. If you increase the pressure of the water coming out of the
  hose, it hits the waterwheel with a lot more force and the wheel turns
  faster, generating more power. If you increase the flow rate, the
  waterwheel turns faster because of the weight of the extra water
  hitting it.

This explanation contrasts two ways of increasing the power:

increasing the pressure [volts] or
increasing the flow rate [amps].

But increasing the pressure also increases the flow rate!? What am I missing here?

Would it be more precise to say that I can increase the power by:

increasing the pressure [volts] while keeping flow rate [amps] the same (by using hose with smaller diameter [increasing resistance]) or
increasing the flow rate [amps] while keeping the pressure [volts] the same (by using hose with bigger diameter [decreasing resistance]?

Does increasing water pressure while reducing hose diameter (so that flow rate stays the same) really give you more powerful waterwheel?


texts: current direction under the other condition and situation

texts:
I read a paper and simulate its schematic recently,and my simulation is not the same as authors,so i want to ask something.I hope i can know the answer from  theory,and not from the simulation now.

Q1:
when current source(positive half wave) charge \$C1\$ and \$BAT1\$ flow through  the \$L1\$,the current direction should be like this

After charge \$C1\$ to a V,and flow through \$L1\$ to b V,b is higher than a.The SW1 close and SW2 opened.At this moment,what is the current direction? Theoretically shoule be "A" direction,because the current direction should be high voltage to low voltage.But my classmate told me the current in the inductor can't change suddenly,and the paper said the direction is "B".Why?i am confused now.

Q2:

At the beginning,A point have aV,and B point have bV,b is higher than a.

Then,the capacitor energy will flow to the inductor to let the inductor's energy flow to the capacitor,so the A point voltage will become from a to -b,the B point will become from b to a.It is like there is a force from A point to push to B point to let the energy from B flow to A.Now if i add a vpulse at B point,and at this moment,the vpulse voltage is 0.that is,the B point voltage is 0 now,will one of these two force be disappeared to let A point won't become -b and B point won't become a ?


texts:
Is there any electrical or other physical property that can tell me the shape of a wire? I mean, if I inserted a wire into a space (of the same thickness as the wire assume), this property should allow me to detect the shape of the wire, and hence, by extension, the shape of the space it was inserted into.

The "wire" could also be any material or optical fiber cable.


texts: Is it safe to directly connect an infrared led to an Arduino?

texts:
I have a KY-005 infrared transmitter connected to my Arduino Uno. But currently I can't get it to work. On this website it says that you must connect the led directly to a digital pin on the Arduino, which I have not done (I connected it in series with a 220 ohm resistor. Because i don’t Thrust the led can handle it)

Is it correct that you can/must connect it directly?

Update: i hooked up the led directly to the arduino pin 3 (not +5V) and that did. it now works


texts:
I'm using ARM Cortex-R4 for my system. I'm little bit confused about which linux should I go for - Standard Linux Kernel with MMU disabled or uCLinux.

On an eval board, I have run the standard kernel compiled with MMU disabled. I used cramfs filesystem which available on the official ARM website. After the kernel boots up, I receive the shell but I couldn't do much experimentation as I found that most of the time, the shell stops responding (particularly when I press  for auto-completion).

So, I'm still not sure whether MMU less kernel shall run smoothly if I use correct filesystem. Also, which distro (buildroot?) should I use for the no-VM Linux?

Any idea or suggestion is welcomed.


texts: Altium Convert .PrjPcb to .PrjMbd - Single Board to Multiple Board?

texts:
I started my project single PCB board. But now, I need multiple boards for this project.
How can I convert my file format? How can I convert my Schematic Diagrams for multiple board project? How can I convert .PrjPcb to .PrjMbd?


texts: Measuring Output Ripple voltage in Scope

texts:
I have a DC-DC converter which converts 16V to 23V. I have an output E-Cap at the end of the converter.
I need to measure the ripple voltage at the E-Cap. I am using a 300MHz scope.

I connect my probe to the positive terminal of E-cap and ground the scope ground with my board ground. I am using the scope in Auto Mode.

I have sent the horizontal scale at 100mV/div and Vertical scale at 2us/div.

I see the voltage signal continuously running and at certain moments when I see the peak values, I stop the reading. I get different values at different instances. How to measure the ripple voltage now?

And how will I set the trigger point if I dont know the max ripple voltage?

Can you please help me?